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<strong>Journal</strong> <strong>of</strong> <strong>Cell</strong> <strong>and</strong> Molecular Biology 5: 71-79, 2006.<br />

Haliç University, Pr<strong>in</strong>ted <strong>in</strong> Turkey.<br />

<strong>Sterols</strong> <strong>and</strong> <strong>the</strong> <strong>phytosterol</strong> <strong>content</strong> <strong>in</strong> <strong>oilseed</strong> <strong>rape</strong> (Brassica napus L.)<br />

Muhammet Kemal Gül *1 <strong>and</strong> Samija Amar 2<br />

1 Çanakkale Onsekiz Mart University Department <strong>of</strong> Field Crops, 17020 Çanakkale, Turkey<br />

2 Goett<strong>in</strong>gen Georg-August University Department für Nutzpflanzenwisschenschaften, A b t e i l u n g<br />

Pflanzenzüchtung Von-Siebold Str. 8 37075 Goett<strong>in</strong>gen/, Germany (*author for correspondence)<br />

Received 23 February 2006; Accepted 12 July 2006<br />

Abstract<br />

<strong>Sterols</strong> are natural, organic compounds with a molecular nucleus <strong>of</strong> 17 carbon atoms <strong>and</strong> a characteristic threedimensional<br />

arrangement <strong>of</strong> four r<strong>in</strong>gs. From <strong>the</strong> chemical po<strong>in</strong>t <strong>of</strong> view sterols are steroid alcohols <strong>and</strong> <strong>the</strong>ir name<br />

is derived from Greek stereos, which mean solid with end<strong>in</strong>g –ol, which is <strong>the</strong> suffix for alcohols. As essential<br />

constituents <strong>of</strong> cell membranes, <strong>the</strong>y are widely distributed <strong>in</strong> all eukaryotic organisms. Play<strong>in</strong>g a structural role <strong>in</strong><br />

cellular membranes, <strong>the</strong>y present a significant part <strong>of</strong> <strong>the</strong> organism membrane biomass, while <strong>the</strong>ir functional role is<br />

evident through <strong>the</strong> participation <strong>in</strong> <strong>the</strong> control <strong>of</strong> membrane-associated metabolic processes, such as: regulations <strong>of</strong><br />

membrane permeability <strong>and</strong> fluidity, signal transduction events <strong>and</strong> <strong>the</strong> activity <strong>of</strong> membrane-bound enzymes.<br />

<strong>Sterols</strong> are <strong>the</strong> precursors <strong>of</strong> steroid hormones <strong>and</strong> bile acids <strong>in</strong> humans, brass<strong>in</strong>osteroids - phytohormones <strong>in</strong> plants<br />

<strong>and</strong>, as <strong>the</strong> recent identifications <strong>of</strong> sterol mutants have shown, <strong>the</strong>y are <strong>in</strong>volved <strong>in</strong> important growth <strong>and</strong><br />

developmental processes <strong>in</strong> liv<strong>in</strong>g organisms. In recent years <strong>in</strong>creased <strong>in</strong>terest <strong>in</strong> <strong>phytosterol</strong>s lies <strong>in</strong> <strong>the</strong>ir potential<br />

to reduce plasma low-density lipoprote<strong>in</strong> cholesterol level, decreas<strong>in</strong>g coronary mortality <strong>and</strong> <strong>the</strong>refore act<strong>in</strong>g as<br />

naturally preventive dietary product. In <strong>the</strong> last decades, more than 40 different sterols were well identified <strong>in</strong><br />

different cultivars. These sterols are called <strong>phytosterol</strong>s <strong>and</strong> <strong>the</strong>y are predom<strong>in</strong>antly present <strong>in</strong> <strong>oilseed</strong> plants. The<br />

<strong>phytosterol</strong> <strong>content</strong> range between 1.41-15.57 gr/ kg oil <strong>and</strong> this depends to plant species. Oilseed <strong>rape</strong> is one <strong>of</strong> <strong>the</strong><br />

most important oil seed crop <strong>in</strong> <strong>the</strong> world. <strong>phytosterol</strong> <strong>content</strong> <strong>in</strong> new <strong>oilseed</strong> <strong>rape</strong> varieties rang between 5.13 <strong>and</strong><br />

9.79 gr/kg oil.<br />

Key Words: Sterol, <strong>phytosterol</strong> <strong>oilseed</strong> <strong>rape</strong>, plant, human<br />

Kolza bitkis<strong>in</strong>de (Brassica napus L.) sterol ve fitosterol içeri¤i<br />

Özet<br />

Steroller organik bileflikler olup 17 karbon atomundan ve 3 boyutlu dört halka dizis<strong>in</strong>den oluflmufllard›r. Kimyasal<br />

aç›da bak›ld›¤›nda steroller steroid alkolü olup, sterol ad› Yunanca’da stereos, dayan›kl› yada bozulmayan anlam›na<br />

gelmektedir. Sterolün sonuna eklenen –ol tak›s› ise alkolden gelmektedir. Hücre membranlar›n›n özel yap›s›ndan<br />

dolay› steroller tüm okaryotik canlilarda bulunurlar. Hücre membran›nda yap›sal bir rol oynad›klar›ndan steroller<br />

organizmalar›n membranlar›n›n önemli bir k›sm›n› teflkil ederken, hücre membran› geçirgenli¤<strong>in</strong>de önemli görevler<br />

alarak bu sistem iç<strong>in</strong>de görev alan enzimler<strong>in</strong> aktif hale getirmektirler. Son olarak steroller<strong>in</strong> <strong>in</strong>sanlarda öncü steroid<br />

hormanlar› ile safra asitler<strong>in</strong>i, bitkilerde brass<strong>in</strong>osteroidler ile fitohormonlar› etkiledi¤<strong>in</strong>i, son yap›lan çal›flmalarda<br />

da steroller<strong>in</strong> canl› organizmalar›n önemli büyüme ve geliflme evreler<strong>in</strong>de rol ald›klar› saptanm›flt›r. Son y›llarda<br />

fitosteroller<strong>in</strong> LDL kolesterol düzenleyicisi özellikleri, kroner ölümleri azalt›c› etkileri bak›m›ndan do¤al önleme<br />

ürünü olmalar› sebebiyle önemleri artm›flt›r. Bitkilerde çok iyi tespit edilip belirlenen 40’dan fazla farkl› sterol<br />

bulunmufltur. Bu steroller ço¤unlukla ya¤ bitkiler<strong>in</strong>de saptanarak fitosterol olarak adl<strong>and</strong>›r›lm›fllard›r. Yap›lan<br />

çal›flmalarda kültür bitkis<strong>in</strong>e göre elde edilen 1 kg ya¤da bulunabilecek fitosterol iktar› 1,41-15,57 gr/kg arala¤›nda<br />

oldu¤u saptanm›flt›r. Kolza dünyada üretilen en önemli ya¤ bitkiler<strong>in</strong>den biridir. Kolzada fitosteroller miktar› 5,13 ile<br />

9,79 gr/kg ya¤ aras›nda de¤iflim göstermektedir.<br />

Anahtar Sözcükler: Sterol, fitosterol, kolza, bitki, <strong>in</strong>san<br />

71


72 M. Kemal Gül <strong>and</strong> Samija Amar<br />

Introduction<br />

<strong>Sterols</strong> are natural, organic compounds <strong>and</strong> <strong>the</strong>y are<br />

widely distributed <strong>in</strong> all eukaryotic organisms. They<br />

present a significant part <strong>of</strong> <strong>the</strong> organism membrane<br />

biomass, while <strong>the</strong>ir functional role is evident through<br />

<strong>the</strong> participation <strong>in</strong> <strong>the</strong> control <strong>of</strong> membraneassociated<br />

metabolic processes, such as: regulations <strong>of</strong><br />

membrane permeability <strong>and</strong> fluidity, signal<br />

transduction events <strong>and</strong> <strong>the</strong> activity <strong>of</strong> membranebound<br />

enzymes (Piironen et al., 2000). <strong>Sterols</strong> are <strong>the</strong><br />

precursors <strong>of</strong> steroid hormones <strong>and</strong> bile acids <strong>in</strong><br />

humans, brass<strong>in</strong>osteroids - phytohormones <strong>in</strong> plants<br />

<strong>and</strong>, as <strong>the</strong> recent identifications <strong>of</strong> sterol mutants have<br />

shown (L<strong>in</strong>dsey et al., 2003), <strong>the</strong>y are <strong>in</strong>volved <strong>in</strong><br />

important growth <strong>and</strong> developmental processes <strong>in</strong><br />

liv<strong>in</strong>g organisms (Hartmann, 1998). Plants have a<br />

variety <strong>of</strong> more than 40 well-identified <strong>and</strong> studied<br />

sterols (Law, 2000), which are termed <strong>phytosterol</strong>s <strong>and</strong><br />

are predom<strong>in</strong>antly present <strong>in</strong> <strong>oilseed</strong> plants. Cereals<br />

are recognised as a significant source <strong>of</strong> <strong>phytosterol</strong>s<br />

as well, whereas <strong>phytosterol</strong> <strong>content</strong> <strong>in</strong> vegetables <strong>and</strong><br />

nuts is considerably lower (Piironen et al., 2000;<br />

Piironen et al., 2003; Normen et al., 1999). The most<br />

abundant <strong>phytosterol</strong>s are: sitosterol, campesterol <strong>and</strong><br />

stigmasterol. O<strong>the</strong>r <strong>phytosterol</strong>s like avenasterol <strong>and</strong><br />

cycloartenol are syn<strong>the</strong>sised earlier <strong>in</strong> <strong>the</strong> biosyn<strong>the</strong>tic<br />

pathway <strong>and</strong> as sterol precursors <strong>the</strong>y usually occur <strong>in</strong><br />

relatively smaller amounts (Määttä et al., 1999).<br />

Phytosterols are, with respect to <strong>the</strong>ir physiological<br />

function <strong>and</strong> <strong>the</strong>ir chemical structure, similar to <strong>the</strong><br />

major <strong>and</strong> only animal produced sterol – cholesterol.<br />

Increased scientific <strong>in</strong>terest <strong>and</strong> economic<br />

importance, <strong>in</strong> <strong>the</strong> past few decades, <strong>in</strong> <strong>the</strong> most<br />

important oil crop <strong>in</strong> Europe – <strong>rape</strong>seed, has been<br />

largely due to its improved quality <strong>of</strong> oil seeds, which<br />

can yield between 40 <strong>and</strong> 47 percentages <strong>of</strong> oil<br />

(Becker et al., 1999). Brassica napus L., known as<br />

<strong>rape</strong>seed, <strong>rape</strong>, or <strong>in</strong> some cultivars, low <strong>in</strong> erucic acid<br />

<strong>and</strong> glucos<strong>in</strong>olate <strong>content</strong>, as canola, belongs to <strong>the</strong><br />

genus B r a s s i c a , which is a member <strong>of</strong> <strong>the</strong><br />

Brassicaceae (Cruciferae) f a m i l y. This family, <strong>of</strong><br />

about 375 genera <strong>and</strong> 3200 species, <strong>in</strong>cludes crops,<br />

condiments <strong>and</strong> ornamentals but only genus Brassica<br />

is well known for <strong>the</strong>ir admirable phenotypical<br />

diversity: cabbage, cauliflower, broccoli, Brussels<br />

sprouts, kohl-rabi, turnip, black <strong>and</strong> white mustards,<br />

garden cress <strong>and</strong> so forth (Gomez-Campo, 1999). Like<br />

o<strong>the</strong>r vegetable oils, <strong>the</strong> <strong>rape</strong>seed oil is <strong>the</strong> richest<br />

natural source <strong>of</strong> <strong>phytosterol</strong>s. Apart from <strong>phytosterol</strong>s<br />

<strong>rape</strong>seed oil is predom<strong>in</strong>antly composed <strong>of</strong> fatty acids,<br />

such as oleic acid, l<strong>in</strong>oleic <strong>and</strong> l<strong>in</strong>olenic acid (vitam<strong>in</strong><br />

F complex), <strong>of</strong> phospho- <strong>and</strong> glycolipids <strong>and</strong> <strong>of</strong><br />

tocopherols (vitam<strong>in</strong> E) <strong>and</strong> carotenoids - pro-vitam<strong>in</strong><br />

A (Rehm <strong>and</strong> Espig, 1991). Therefore, it became<br />

reasonable to <strong>in</strong>crease <strong>the</strong> <strong>rape</strong>seed oil production.<br />

Accord<strong>in</strong>g to “Food Outlook” (FAO, 2004) from Food<br />

<strong>and</strong> Agriculture Organisation <strong>of</strong> <strong>the</strong> United Nations,<br />

global production <strong>of</strong> <strong>rape</strong>seed crop rose more than<br />

10 % from 1998 to 2002, with <strong>the</strong> estimation for 2004<br />

that it will reach second place after soybean.<br />

Encouraged with <strong>the</strong> development <strong>of</strong> improved <strong>rape</strong><br />

cultivars with high quality edible oils <strong>and</strong> most recent<br />

utilisation <strong>of</strong> <strong>rape</strong>seed oil for bio-diesel (biogenic fuel)<br />

production (UFOP, 2004), <strong>the</strong> EU farmers exp<strong>and</strong>ed<br />

<strong>rape</strong>seed plant<strong>in</strong>g, exceed<strong>in</strong>g those <strong>of</strong> soybean,<br />

sunflower, groundnut <strong>and</strong> cottonseed (Kimber <strong>and</strong><br />

McGregor, 1995).<br />

Literature review<br />

Phytosterols have been isolated from a large number<br />

<strong>of</strong> species <strong>and</strong> accord<strong>in</strong>g to numerous publications<br />

(Grunwald, 1980; Gordon <strong>and</strong> Miller, 1997; Dutta <strong>and</strong><br />

Normen, 1998; Piironen et al., 2000) <strong>the</strong>y probably<br />

exist <strong>in</strong> all angiosperm <strong>and</strong> gymnosperm species.<br />

Although, <strong>the</strong>re are more than 40 diff e r e n t<br />

<strong>phytosterol</strong>s found <strong>in</strong> higher plants, sitosterol,<br />

campesterol <strong>and</strong> stigmasterol <strong>of</strong>ten predom<strong>in</strong>ate,<br />

while o<strong>the</strong>r <strong>phytosterol</strong>s are usually typical only for<br />

certa<strong>in</strong> plant family or even species. Brassicasterol is<br />

for example typical only for Brassicaceae family, <strong>and</strong><br />

<strong>the</strong>refore it could be used for identification<br />

(Benveniste, 2002).<br />

Chemical structure <strong>and</strong> properties<br />

<strong>Sterols</strong> belong to a large group <strong>of</strong> hydrocarbons,<br />

o rganic chemical compounds known as<br />

polyisoprenoids with carbon skeletons structurally<br />

based <strong>and</strong> derived from multiple isoprene, five carbon<br />

unit -CH 2=C(CH 3)CH=CH 2. <strong>Sterols</strong> are, toge<strong>the</strong>r with<br />

tocopherols, carotenoids <strong>and</strong> chlorophylls, formed by<br />

polymerisation <strong>of</strong> isoprene unit (Grunwald, 1980).<br />

The structural feature, which virtually all sterols<br />

have <strong>in</strong> common, is that <strong>the</strong>y are derivatives <strong>of</strong> a<br />

tetracyclic perhydro-cyclopentano-phenanthrene r<strong>in</strong>g<br />

system with a flexible side cha<strong>in</strong> at <strong>the</strong> C-17 atom<br />

(Figure 1) <strong>and</strong> 3β-monohydroxy compounds <strong>and</strong><br />

(Hartmann, 1998).


Animal cells conta<strong>in</strong> only one major sterol, i.e.<br />

c h o l e s t e ro l (Figure 2a). Cholesterol also occurs,<br />

though only <strong>in</strong> a few percentage <strong>of</strong> <strong>the</strong> whole sterol<br />

<strong>content</strong>, <strong>in</strong> plants (Gordon <strong>and</strong> Miller, 1997).<br />

Chemically, it is an analogue to <strong>the</strong> <strong>phytosterol</strong>s,<br />

differ<strong>in</strong>g only <strong>in</strong> <strong>the</strong> side cha<strong>in</strong>. Fungal cells, toge<strong>the</strong>r<br />

with some unicellular algae <strong>and</strong> lichens syn<strong>the</strong>sise<br />

ergosterol - provitam<strong>in</strong> D2 (Grunwald, 1980; Rehm<br />

<strong>and</strong> Espig, 1991). Namely, ergocalciferol (vitam<strong>in</strong> D2)<br />

is produced by ultraviolet irradiation <strong>of</strong> provitam<strong>in</strong> D2<br />

( e rgosterol), which occurs <strong>in</strong> yeast <strong>and</strong> fungi (Figure 2b).<br />

In contrast to animal cells <strong>and</strong> fungi, plant cells<br />

syn<strong>the</strong>size complex array <strong>of</strong> <strong>phytosterol</strong> mixtures with<br />

<strong>the</strong> sterol pr<strong>of</strong>iles vary<strong>in</strong>g between species.<br />

The scientific names <strong>of</strong> <strong>phytosterol</strong>s are given to<br />

<strong>the</strong>m accord<strong>in</strong>g to <strong>the</strong> number <strong>of</strong> C atoms <strong>in</strong> <strong>the</strong> C-17<br />

side cha<strong>in</strong>, <strong>the</strong> number <strong>and</strong> <strong>the</strong> position <strong>of</strong> <strong>the</strong> double<br />

<strong>Sterols</strong> <strong>and</strong> <strong>phytosterol</strong>s <strong>in</strong> <strong>oilseed</strong> <strong>rape</strong> 73<br />

Figure 1. Chemical structure <strong>of</strong> 5 α cholestan 3β-ol (adapted from Piironen et al., 2000)<br />

a. b.<br />

bond <strong>in</strong> <strong>the</strong> r<strong>in</strong>g system <strong>and</strong> <strong>the</strong> side cha<strong>in</strong>. Their<br />

scientific names are usually very complex, so <strong>the</strong> most<br />

common <strong>phytosterol</strong>s are referred to by <strong>the</strong>ir trivial<br />

names. The trivial <strong>and</strong> <strong>the</strong> scientific names <strong>of</strong> <strong>the</strong> most<br />

important <strong>phytosterol</strong>s are given <strong>in</strong> Table 1.<br />

Accord<strong>in</strong>g to <strong>the</strong> IUPAC recommendations from<br />

1989, sterol molecules consist <strong>of</strong> four r<strong>in</strong>gs marked as<br />

A, B, C <strong>and</strong> D with st<strong>and</strong>ard carbon number<strong>in</strong>g<br />

(Figure 1). Three r<strong>in</strong>gs, A, B <strong>and</strong> C, have 6 carbons<br />

atom nonl<strong>in</strong>ear structure <strong>and</strong> <strong>the</strong>y are fused to one 5<br />

carbons atom r<strong>in</strong>g (D). The various <strong>phytosterol</strong>s found<br />

<strong>in</strong> plants differ <strong>in</strong> number <strong>of</strong> C atom <strong>in</strong> <strong>the</strong> side cha<strong>in</strong><br />

at <strong>the</strong> C-17 atom <strong>and</strong> <strong>the</strong> position <strong>and</strong> <strong>the</strong> number <strong>of</strong><br />

<strong>the</strong> double bonds <strong>in</strong> <strong>the</strong> r<strong>in</strong>g system. T h e<br />

predom<strong>in</strong>at<strong>in</strong>g <strong>phytosterol</strong>s <strong>in</strong> plants are: campesterol<br />

sometimes referred to as 24-methylcholesterol (Figure<br />

3a), sitosterol (Figure 3c) <strong>and</strong> stigmasterol (Figure 3d).<br />

Figure 2. Chemical structure <strong>of</strong> a. cholesterol <strong>and</strong> b. ergosterol (taken from Kyoto Encyclopedia <strong>of</strong> Genes <strong>and</strong> Genomes, 2004)


74 M. Kemal Gül <strong>and</strong> Samija Amar<br />

The <strong>phytosterol</strong> composition <strong>of</strong> family Brassicaceae<br />

to which <strong>rape</strong>seed belongs, differ from most plant<br />

species for an additional brassicasterol (Figure 3e)<br />

while avenasterol (Figure 3b) is considered as one <strong>of</strong><br />

<strong>the</strong> ma<strong>in</strong> <strong>phytosterol</strong> <strong>in</strong> cereals but, as it has been<br />

discussed (Dutta <strong>and</strong> Normen, 1998; Piironen et al.,<br />

2002), avenasterol also occurs <strong>in</strong> Brassica napus seed.<br />

In addition to <strong>the</strong>ir vast structural variations,<br />

aris<strong>in</strong>g from different substitution <strong>in</strong> <strong>the</strong> side cha<strong>in</strong> <strong>and</strong><br />

number <strong>and</strong> <strong>the</strong> position <strong>of</strong> double bonds <strong>in</strong> <strong>the</strong><br />

tetracyclic skeleton, different <strong>phytosterol</strong>s play<br />

various roles <strong>in</strong> higher plants. Yet, it still rema<strong>in</strong>s<br />

unknown why do plants require a mixture <strong>of</strong><br />

<strong>phytosterol</strong>s <strong>in</strong>stead <strong>of</strong> only one like animals <strong>and</strong> fungi<br />

<strong>and</strong> does each <strong>phytosterol</strong> play a specific function <strong>in</strong><br />

plant metabolism? Fur<strong>the</strong>r on, for <strong>the</strong> <strong>phytosterol</strong><br />

classification, it is important whe<strong>the</strong>r <strong>the</strong> different side<br />

cha<strong>in</strong>s, or functional groups <strong>of</strong> r<strong>in</strong>gs system, are <strong>in</strong> α,<br />

i.e. under <strong>the</strong> pla<strong>in</strong> <strong>of</strong> <strong>the</strong> cyclic system, or above <strong>the</strong><br />

pla<strong>in</strong> - <strong>in</strong> a β position (IUPAC, 1989). For example,<br />

<strong>the</strong> side cha<strong>in</strong> <strong>and</strong> <strong>the</strong> two methyl groups at C-18 <strong>and</strong><br />

C-19 are angular to <strong>the</strong> r<strong>in</strong>g structure <strong>and</strong> above <strong>the</strong><br />

plane, thus hav<strong>in</strong>g β-stereochemistry, with additional<br />

3-hydroxyl group also hav<strong>in</strong>g β- s t e r e o c h e m i s t r y<br />

(Figure 1). Ano<strong>the</strong>r characteristic specific only to<br />

<strong>phytosterol</strong>s is <strong>the</strong> alkylation <strong>of</strong> a C atom at 24 th<br />

position (Figure 3). Sitosterol <strong>and</strong> stigmasterol have<br />

an ethyl group at C-24 <strong>in</strong> α-position, whereas<br />

campesterol a methyl group at α- <strong>and</strong> brassicasterol a<br />

methyl group at β-position (Table 1). Accord<strong>in</strong>g to<br />

<strong>the</strong>ir structural <strong>and</strong> biosyn<strong>the</strong>tical basis, <strong>phytosterol</strong>s<br />

can be divided <strong>in</strong>to three groups: 4-desmethyl, 4monomethyl<br />

<strong>and</strong> 4,4-dimethyl <strong>phytosterol</strong>s (Table. 1).<br />

Most abundant are three 4-desmethyl sterols:<br />

sitosterol, campesterol <strong>and</strong> stigmasterol. O<strong>the</strong>r<br />

<strong>phytosterol</strong>s like 4-mono- <strong>and</strong> 4,4-dimethyl sterols are<br />

syn<strong>the</strong>sised earlier <strong>in</strong> biosyn<strong>the</strong>tic pathway, so <strong>the</strong>y are<br />

ma<strong>in</strong>ly sterol precursors <strong>and</strong> usually occur <strong>in</strong><br />

relatively smaller amounts (Määttä et al., 1999). The<br />

last two are mostly precursors <strong>of</strong> <strong>the</strong> sterol<br />

biosyn<strong>the</strong>tical pathway <strong>and</strong> exist <strong>in</strong> lower level. The 4desmethyl<br />

sterols can also be dist<strong>in</strong>guished accord<strong>in</strong>g<br />

to <strong>the</strong>ir saturation <strong>and</strong> position <strong>of</strong> double bond on <strong>the</strong><br />

C-5 <strong>and</strong> C-7 atoms <strong>in</strong> <strong>the</strong> B r<strong>in</strong>g (Figure 1). The<br />

unsaturated sterols are marked with Δ 5 <strong>and</strong> Δ 7 ,<br />

r e s p e c t i v e l y. Most <strong>phytosterol</strong>s (e.g. stigmasterol,<br />

sitosterol, campesterol, brassicasterol <strong>and</strong> avenasterol)<br />

belong to <strong>the</strong> group <strong>of</strong> Δ 5 unsaturated <strong>phytosterol</strong>s.<br />

Phytosterols with ethyl group at <strong>the</strong> 24 th C-atom - 24-<br />

ethylsterols (sitosterol, stigmasterol <strong>and</strong> avenasterol),<br />

ma<strong>in</strong>ly have only one type <strong>of</strong> configuration: 24α.<br />

Accord<strong>in</strong>g to Salo et al. (2003) <strong>and</strong> Hartmann (1998),<br />

24-methylsterols can consist <strong>of</strong> a mixture <strong>of</strong> two<br />

epimers. That is to say, 24-methylsterol is a mixture <strong>of</strong><br />

2 4α-methylsterol <strong>and</strong> 24β-methylsterol know as<br />

campesterol or 22,23 dihydrobrassicasterol (Figure 3a).<br />

Phytosterols are largely hydrophobic hav<strong>in</strong>g one<br />

polar - hydroxyl group at 3 rd C-atom, mak<strong>in</strong>g <strong>the</strong>m<br />

amphiphilic. Accord<strong>in</strong>g to one <strong>of</strong> <strong>the</strong> sterol<br />

classifications <strong>phytosterol</strong>s with free 3β- hydroxyl<br />

group, are named free <strong>phytosterol</strong>s (Figure 3) <strong>and</strong> <strong>the</strong>y<br />

are <strong>the</strong> major end product <strong>of</strong> biosyn<strong>the</strong>tic pathway <strong>of</strong><br />

<strong>phytosterol</strong>s. However, <strong>phytosterol</strong>s also occur as<br />

steryl esters where 3β-hydroxyl group <strong>of</strong> free<br />

<strong>phytosterol</strong>s is esterified with a long cha<strong>in</strong> <strong>of</strong> saturated<br />

or unsaturated fatty acids (Figure 4a), ma<strong>in</strong>ly l<strong>in</strong>oleic<br />

<strong>and</strong> oleic, or with phenolic acids (Figure 4d). Steryl<br />

glycosides are formed when <strong>the</strong> 3β-hydroxyl group is<br />

l<strong>in</strong>ked with monosaccharides, usually glucose, at <strong>the</strong><br />

first C position (Figure 4c).<br />

When this monosaccharide is at <strong>the</strong> 6-C position<br />

esterified with fatty acid, than so-called acylated steryl<br />

glycosides are formed (Figure 4b).<br />

Biological functions <strong>in</strong> plants<br />

Phytosterols have both structural <strong>and</strong> metabolic<br />

functions. Structural role is obvious through <strong>the</strong> fact<br />

that <strong>the</strong>y are <strong>in</strong>tegral membrane components. Be<strong>in</strong>g<br />

<strong>in</strong>corporated <strong>in</strong>to membranes <strong>the</strong>y are determ<strong>in</strong><strong>in</strong>g <strong>the</strong><br />

characteristics <strong>of</strong> plasma membrane <strong>and</strong>, additionally,<br />

<strong>of</strong> endoplasmic reticulum <strong>and</strong> mitochondria<br />

membranes. Most likely, <strong>the</strong>y also have a certa<strong>in</strong><br />

function <strong>in</strong> <strong>the</strong> membrane adaptation to temperature<br />

variations (Piironen et al., 2000). Participat<strong>in</strong>g <strong>in</strong> <strong>the</strong><br />

control <strong>of</strong> metabolic processes, such as regulation <strong>of</strong><br />

membrane permeability, fluidity, signal transduction<br />

events for cell division <strong>and</strong> even activity <strong>of</strong><br />

membrane-bound enzymes, <strong>the</strong>y fulfil <strong>the</strong>ir metabolic<br />

role (Hartmann, 1998; L<strong>in</strong>dsay et al., 2003).<br />

Interact<strong>in</strong>g with <strong>the</strong>ir side cha<strong>in</strong>, with <strong>the</strong> fatty acyl<br />

moiety <strong>of</strong> membrane phospholipids <strong>and</strong> prote<strong>in</strong>s<br />

complexes, <strong>phytosterol</strong>s restrict <strong>the</strong> motion <strong>of</strong><br />

membrane bilayers (i.e. <strong>the</strong> sterol order<strong>in</strong>g effect),<br />

regulat<strong>in</strong>g membrane fluidity (Nes, 1987).<br />

It has been postulated that sitosterol <strong>and</strong><br />

campesterol are most efficient <strong>in</strong> membrane<br />

permeability <strong>and</strong> fluidity regulation <strong>and</strong> <strong>the</strong>re are


a. b.<br />

d. e.<br />

evidence that stigmasterol play an important role <strong>in</strong><br />

cell proliferation, but has reduced order<strong>in</strong>g effect<br />

(Hartmann, 1998). F<strong>in</strong>ally, it appears that <strong>the</strong>y<br />

<strong>in</strong>fluence <strong>the</strong> plant development through <strong>the</strong><br />

localisation <strong>and</strong> functionality <strong>of</strong> key regulatory<br />

prote<strong>in</strong>s (L<strong>in</strong>dsey et al., 2003). Dur<strong>in</strong>g <strong>the</strong> seed<br />

germ<strong>in</strong>ation, <strong>the</strong> <strong>phytosterol</strong> <strong>content</strong> <strong>in</strong>creases, which<br />

is due to <strong>in</strong>tensive membrane biosyn<strong>the</strong>sis.<br />

Phytosterols that are accumulated <strong>in</strong> seeds <strong>and</strong><br />

meristematic tissue are play<strong>in</strong>g an important role <strong>in</strong><br />

cellular proliferation <strong>and</strong> differentiation. Fur<strong>the</strong>rmore,<br />

<strong>in</strong> youngest plant tissues, <strong>the</strong> membrane biosyn<strong>the</strong>sis<br />

is more <strong>in</strong>tensive. Consequently, <strong>phytosterol</strong> syn<strong>the</strong>sis<br />

will appear mostly dur<strong>in</strong>g <strong>the</strong> seed formation <strong>and</strong><br />

germ<strong>in</strong>ation <strong>and</strong> <strong>phytosterol</strong>s <strong>the</strong>mselves will provide<br />

a supply for <strong>the</strong> growth <strong>of</strong> new cells <strong>and</strong> young shoots.<br />

By <strong>the</strong> time when seeds are already mature or tissues<br />

ages, <strong>the</strong> <strong>in</strong>tensity <strong>of</strong> biosyn<strong>the</strong>sis will decl<strong>in</strong>e<br />

(Grunwald, 1980). Besides, <strong>the</strong> high <strong>phytosterol</strong><br />

amount could be also largely expla<strong>in</strong>ed by <strong>the</strong><br />

anatomical structure <strong>of</strong> different plant tissues. For<br />

<strong>in</strong>stance, flower heads <strong>of</strong> broccoli <strong>and</strong> cauliflower<br />

(Brassica oleracea L. ) have higher proportion <strong>of</strong><br />

membrane-rich meristematic tissue, which results <strong>in</strong><br />

<strong>Sterols</strong> <strong>and</strong> <strong>phytosterol</strong>s <strong>in</strong> <strong>oilseed</strong> <strong>rape</strong> 75<br />

Figure 3. Examples <strong>of</strong> <strong>the</strong> most important <strong>phytosterol</strong>s show<strong>in</strong>g <strong>the</strong> difference <strong>in</strong> <strong>the</strong>ir chemical structure: a. campesterol,<br />

b. avenasterol, c. sitosterol, d. stigmasterol <strong>and</strong> e. brassicasterol (taken from Kyoto Encyclopedia <strong>of</strong> Genes <strong>and</strong> Genomes, 2004)<br />

c.<br />

higher <strong>content</strong> <strong>of</strong> total <strong>phytosterol</strong>s <strong>in</strong> this species <strong>in</strong><br />

comparison with o<strong>the</strong>r vegetables, fruits or berries<br />

(Piironen et al., 2003; Normen et al., 1999).<br />

M o r e o v e r, free <strong>phytosterol</strong>s are precursors <strong>of</strong><br />

bioactive steroids, growth factors <strong>and</strong> substrates for<br />

syn<strong>the</strong>sis <strong>of</strong> numerous secondary plant metabolites<br />

(Willmann, 2000; Piironen et al., 2003). Campesterol<br />

is <strong>the</strong> precursor <strong>of</strong> brass<strong>in</strong>osteroids - phytohormones<br />

found <strong>in</strong> Brassica pollen (Benveniste, 2002). Plant<br />

steryl esters, <strong>in</strong>tracellularly distributed, represent a<br />

storage form <strong>of</strong> <strong>phytosterol</strong>s, analogously as<br />

cholesterol esters <strong>in</strong> mammalian cells (Piironen et al.,<br />

2000).<br />

Biological functions <strong>of</strong> <strong>phytosterol</strong>s <strong>in</strong> humans<br />

In contrast to <strong>phytosterol</strong>s, cholesterol can be <strong>in</strong><br />

humans, ei<strong>the</strong>r syn<strong>the</strong>sised de novo <strong>in</strong> liver, or taken<br />

up from <strong>the</strong> environment. Dur<strong>in</strong>g <strong>the</strong> process <strong>of</strong><br />

cholesterol absorption, it is be<strong>in</strong>g transported from <strong>the</strong><br />

lumen <strong>of</strong> <strong>in</strong>test<strong>in</strong>e, across <strong>the</strong> <strong>in</strong>test<strong>in</strong>al wall <strong>and</strong> <strong>in</strong>to<br />

<strong>the</strong> blood. Low-density lipoprote<strong>in</strong> (LDL) <strong>the</strong>n<br />

transports cholesterol through <strong>the</strong> blood system.<br />

Narrow<strong>in</strong>g <strong>the</strong> channels <strong>of</strong> <strong>the</strong> blood vessels, LDL-


76 M. Kemal Gül <strong>and</strong> Samija Amar<br />

Figure 4. Examples <strong>of</strong> steryl conjugated structures: a. oleic acid steryl ester, b. palmitic acid steryl glycosides, c. steryl glycosides<br />

<strong>and</strong> d. phenolic acid steryl ester (adapted from Piironen et al., 2000)<br />

cholesterol thus constricts <strong>the</strong> blood flow <strong>and</strong> those<br />

people with high cholesterol levels eventually become<br />

more susceptible to Cardiovascular Diseases (CVD)<br />

such as: coronary heart disease (CHD), also known as<br />

heart attack, hypertension (high blood pressure),<br />

cerebrovascular (stroke) <strong>and</strong> peripheral vascular<br />

diseases (Salo et al., 2003). Accord<strong>in</strong>g to <strong>the</strong> “World<br />

Health Report 2003” <strong>of</strong> United Nations World Health<br />

Organisation, heart attacks <strong>and</strong> strokes kill 12 million<br />

people around <strong>the</strong> world every year, from which,<br />

around 75% <strong>of</strong> CVD can be attributed to <strong>the</strong> major<br />

risks: high cholesterol, high blood pressure <strong>and</strong> low<br />

fruit <strong>and</strong> vegetable <strong>in</strong>take. By 2010 estimations are<br />

that CVD will be <strong>the</strong> lead<strong>in</strong>g cause <strong>of</strong> death <strong>in</strong><br />

develop<strong>in</strong>g countries. S<strong>in</strong>ce <strong>the</strong> medical care <strong>of</strong> CVD<br />

is costly <strong>and</strong> prolonged, <strong>the</strong>re is, consequently, an<br />

evident need for cholesterol suppression.<br />

Accord<strong>in</strong>g to many conducted experiments<br />

<strong>phytosterol</strong>s decreases serum total <strong>and</strong> LDL<br />

cholesterol levels (Gyll<strong>in</strong>g et al., 1997; Miett<strong>in</strong>en,<br />

2001; Niss<strong>in</strong>en et al., 2002; Trautwe<strong>in</strong> et al., 2003). It<br />

was suggested that <strong>phytosterol</strong>s compete at <strong>the</strong> same<br />

time, <strong>in</strong> <strong>the</strong> micellar phase <strong>of</strong> <strong>the</strong> small <strong>in</strong>test<strong>in</strong>e, for<br />

<strong>the</strong> limited space with cholesterol. Micelles are <strong>the</strong><br />

essentially small aggregates, which are carry<strong>in</strong>g a<br />

mixture <strong>of</strong> lipids <strong>and</strong> bile salts <strong>in</strong> <strong>in</strong>test<strong>in</strong>al lumen.<br />

Sitostanol esters, 5α-saturated sitosterol esters, were<br />

recognised as <strong>the</strong> most efficient for reduc<strong>in</strong>g <strong>the</strong> serum<br />

cholesterol concentration <strong>and</strong> <strong>the</strong> <strong>in</strong>test<strong>in</strong>al cholesterol<br />

absorption (Niss<strong>in</strong>en et al., 2002). As it seems <strong>the</strong>y<br />

could be easily produced by sterol hydrogenation <strong>and</strong><br />

trans-esterification with polyunsaturated fatty acids<br />

(Piironen et al., 2000). Sitostanol esters apparently<br />

result similar <strong>in</strong> prevention <strong>of</strong> cholesterol absorption<br />

but, <strong>in</strong> contrast to <strong>phytosterol</strong> esters, <strong>the</strong>y do not<br />

<strong>in</strong>crease <strong>the</strong>ir own absorption. In addition to this fact,<br />

it has been confirmed (Miett<strong>in</strong>en, 2001) that relatively<br />

high campesterol <strong>content</strong>, <strong>in</strong> some <strong>phytosterol</strong><br />

complexes like soy <strong>phytosterol</strong>s for example, can<br />

<strong>in</strong>crease <strong>the</strong> campesterol proportion <strong>in</strong> serum, what<br />

w a s n ’t acknowledged for plant stanols, <strong>in</strong>clud<strong>in</strong>g<br />

campestanol (5α-saturated campesterol). Phytosterol-


ich diets may thus, result <strong>in</strong> symptoms analogue to<br />

<strong>phytosterol</strong>emia, hereditary metabolic disorder<br />

characterised by elevated <strong>phytosterol</strong> level <strong>in</strong> blood<br />

<strong>and</strong> tissue. Additional esterification <strong>of</strong> <strong>phytosterol</strong>s<br />

<strong>and</strong> stanols with long cha<strong>in</strong> <strong>of</strong> mono- or<br />

polyunsaturated fatty acids will <strong>in</strong>crease <strong>the</strong>ir lipid<br />

solubility, facilitat<strong>in</strong>g <strong>the</strong>ir <strong>in</strong>corporation <strong>in</strong>to <strong>the</strong> food,<br />

at <strong>the</strong> same time.<br />

A new <strong>rape</strong>seed margar<strong>in</strong>e Benecol, obta<strong>in</strong>ed from<br />

<strong>rape</strong>seed oil by phytostanols trans-esterification<br />

(Miett<strong>in</strong>en, 2001) <strong>and</strong> enriched with sitostanol-esters<br />

was first launched <strong>in</strong> ’95 <strong>in</strong> F<strong>in</strong>l<strong>and</strong> (Miett<strong>in</strong>en et al.,<br />

1995) <strong>and</strong> by <strong>the</strong> end <strong>of</strong> ’99 already <strong>in</strong>troduced <strong>in</strong><br />

several o<strong>the</strong>r European countries <strong>and</strong> worldwide (Law,<br />

2000). Functional spreadable oils <strong>and</strong> fats, with<br />

correspond<strong>in</strong>g products like: margar<strong>in</strong>e, milk <strong>and</strong><br />

yoghurt, first appeared <strong>in</strong> Germany <strong>in</strong> July 2002,<br />

under <strong>the</strong> product name “Becel pro-activ”. It was<br />

found that 3 g/day <strong>of</strong> phytostanol ester margar<strong>in</strong>e, like<br />

Benecol, could actually reduce <strong>the</strong> LDL cholesterol<br />

level up to 14-22 %, decreas<strong>in</strong>g <strong>the</strong> amount <strong>of</strong><br />

<strong>Sterols</strong> <strong>and</strong> <strong>phytosterol</strong>s <strong>in</strong> <strong>oilseed</strong> <strong>rape</strong> 77<br />

Table 1. Trivial <strong>and</strong> scientific names <strong>of</strong> selected sterols from <strong>the</strong> sterol biosyn<strong>the</strong>tic pathway (adapted from Grunwald, 1980)<br />

Trivial Name Scientific Name Sterol Class<br />

Cycloartenol 9beta,19-cyclo-24-lanosten-3beta-ol 4,4-dimethyl<br />

24-Methylene Lophenol 4-alpha-Methyl-5-alpha-ergosta-7,24-dien-3-beta-ol 4-methyl<br />

Avenasterol 24-ethylcholesta-5,24(28)Z-dien-3‚-ol 4-desmethyl<br />

Cholesterol cholest-5-en-3‚-ol 4-desmethyl<br />

Campesterol 24·-methyl-5-cholestern-3‚-ol 4-desmethyl<br />

Brassicasterol 5,22-cholestadien-24‚-methyl-3‚-ol 4-desmethyl<br />

Sitosterol 24·-ethylcholest-5-en-3‚-ol 4-desmethyl<br />

Stigmasterol 5,22-cholestadien-24·-ethyl-3‚-ol 4-desmethyl<br />

Table 2. Variation <strong>of</strong> <strong>phytosterol</strong> <strong>content</strong> <strong>in</strong> six different vegetable oils (g/kg <strong>of</strong> oil) (adapted from Piironen et al., 2000)<br />

Oil Type Brassicasterol Campesterol Stigmasterol Sitosterol Avenasterol Total Phytosterols<br />

Corn * 2.59 0.98 9.89 0.36 8.09-15.57<br />

Rapeseed 0.55-0.73 1.59-2.48 0.02-0.04 2.84-3.59 0.13-0.19 5.13-9.79<br />

Sunflower - 0.69 0.75 4.65 0.28 3.74-7.25<br />

Cottonseed * 0.26 * 4.00 0.05 4.31-5.39<br />

Soybean - 0.62-0.76 0.45-076 1.22-2.31 - 2.29-4.59<br />

Olive (Extra Virg<strong>in</strong>) - 0.05 0.01 1.18-1.21 0.17-0.18 1.41-1.50<br />

*found <strong>in</strong> traces<br />

-not available<br />

absorbed cholesterol up to 65 % (Law 2000; Miett<strong>in</strong>en<br />

et al., 1995; Miett<strong>in</strong>en, 2001; Jones et al., 1999). The<br />

reduction <strong>of</strong> LDL cholesterol level up to 20 % was,<br />

accord<strong>in</strong>g to Gyll<strong>in</strong>g et al. (1997), achieved with <strong>the</strong><br />

<strong>rape</strong>seed margar<strong>in</strong>e (5 %) <strong>and</strong> with <strong>the</strong> sitostanol<br />

esters (15 %) present <strong>in</strong> that margar<strong>in</strong>e. In this study, it<br />

has been also proven that consumption <strong>of</strong> roughly 2 g<br />

a day <strong>of</strong> <strong>phytosterol</strong>-enriched margar<strong>in</strong>es can decrease<br />

<strong>the</strong> coronary mortality, by about 25 %. Fur<strong>the</strong>rmore,<br />

latest experimental studies have shown that dietary<br />

<strong>phytosterol</strong>s may be used also as prevention for<br />

several types <strong>of</strong> cancer e.g. stomach <strong>and</strong> colon cancer<br />

(Normen et al., 2001).<br />

Genetic variation <strong>and</strong> modification<br />

Gordon <strong>and</strong> Miller (1997) have published results <strong>of</strong> a<br />

steryl ester composition <strong>in</strong> 10 different oil types: corn,<br />

<strong>rape</strong>seed, groundnut, olive, soybean, safflower, oleic<br />

sunflower, l<strong>in</strong>oleic sunflower, cottonseed <strong>and</strong> palm oil.<br />

They have discovered that <strong>rape</strong>seed had, after <strong>the</strong> corn


78 M. Kemal Gül <strong>and</strong> Samija Amar<br />

oil, second highest <strong>phytosterol</strong> proportion <strong>in</strong> oil. The<br />

mean <strong>content</strong> <strong>in</strong> oil <strong>of</strong> five <strong>rape</strong>seed varieties was 6900<br />

mg/kg, <strong>in</strong> which <strong>the</strong> free <strong>phytosterol</strong> fraction equals<br />

65 % <strong>and</strong> <strong>the</strong> steryl ester fraction equals 35 %, <strong>of</strong> <strong>the</strong><br />

total <strong>phytosterol</strong> <strong>content</strong>. They have published that<br />

<strong>the</strong>ir <strong>phytosterol</strong> <strong>content</strong> <strong>in</strong> oil can vary to a great<br />

extent from 6540 mg/kg to 8550 mg/kg <strong>of</strong> oil.<br />

Never<strong>the</strong>less, <strong>the</strong> average total sterol <strong>content</strong> <strong>of</strong><br />

6900mg/kg classifies <strong>rape</strong>seed oil, <strong>in</strong>to oils with <strong>the</strong><br />

highest <strong>content</strong> i.e. higher than 4000 mg/kg <strong>of</strong> oil. On<br />

<strong>the</strong> o<strong>the</strong>r h<strong>and</strong> Appelqvist et al. (1981) ascerta<strong>in</strong>ed <strong>the</strong><br />

<strong>content</strong> <strong>of</strong> free <strong>phytosterol</strong>s <strong>in</strong> <strong>the</strong> total amount <strong>of</strong><br />

<strong>rape</strong>seed oil would be <strong>the</strong>n 0.3 % <strong>and</strong> esterified<br />

<strong>phytosterol</strong>s 0.6 %. Piironen et al. (2000) have<br />

published collected results <strong>of</strong> <strong>phytosterol</strong> <strong>content</strong> <strong>in</strong><br />

crude corn, cottonseed, <strong>rape</strong>seed, olive, soybean <strong>and</strong><br />

sunflower oil (Table. 2), <strong>in</strong> which <strong>the</strong>y have showed<br />

<strong>the</strong> majority <strong>of</strong> crude vegetable oils conta<strong>in</strong>, at least<br />

1 g/kg to 5 g/kg <strong>of</strong> oil. However, <strong>the</strong>y have found that<br />

<strong>the</strong> most significant exceptions are corn (up to 16 g/kg<br />

<strong>of</strong> oil) <strong>and</strong> <strong>rape</strong>seed oil (up to 10 g/kg <strong>of</strong> oil).<br />

Accord<strong>in</strong>g to Abidi et al. (1999) <strong>the</strong> total<br />

<strong>phytosterol</strong> <strong>content</strong> is affected by genetic<br />

modifications. They have compared 10 experimental<br />

transgenic <strong>and</strong> non-transgenic canola genotypes<br />

differ<strong>in</strong>g <strong>in</strong> fatty acid composition <strong>and</strong> concluded that<br />

<strong>the</strong> <strong>phytosterol</strong> <strong>content</strong> was <strong>in</strong>fluenced by <strong>the</strong> genetic<br />

modification <strong>of</strong> <strong>the</strong> fatty acid composition. A<br />

significant decrease <strong>in</strong> amount <strong>of</strong> three major<br />

<strong>phytosterol</strong>s: sitosterol, campesterol <strong>and</strong><br />

brassicasterol, was observed <strong>in</strong> non-transgenic canola<br />

varieties grown for low-l<strong>in</strong>olenic <strong>and</strong> high oleic acid.<br />

In addition, <strong>the</strong> amount <strong>of</strong> brassicasterol varied widely<br />

based on genotype <strong>and</strong> grow<strong>in</strong>g conditions.<br />

Brassicasterol <strong>content</strong> ranged from 85 to 189 mg/100 g<br />

<strong>of</strong> modified oil; campesterol <strong>content</strong> ranged from 205<br />

to 264 mg/100 g; sitosterol from 457 to 509 mg/100 g<br />

<strong>and</strong> f<strong>in</strong>ally variation <strong>of</strong> <strong>the</strong> total <strong>phytosterol</strong> <strong>content</strong>s<br />

was from 766 to 961 mg/100 g <strong>of</strong> modified oil. On <strong>the</strong><br />

o<strong>the</strong>r h<strong>and</strong>, <strong>the</strong>re wasn’t any systematic trend <strong>of</strong><br />

<strong>phytosterol</strong> <strong>content</strong> <strong>in</strong> transgenic canola l<strong>in</strong>es. In his<br />

paper Miett<strong>in</strong>en (2001) discussed on what plant<br />

breeders should focus when try<strong>in</strong>g to develop<strong>in</strong>g new<br />

nutritionally <strong>in</strong>terest<strong>in</strong>g plant with an ideal <strong>phytosterol</strong><br />

<strong>content</strong>, which could be later on used for cholesterollower<strong>in</strong>g<br />

functional food production. He suggested<br />

that ideal <strong>phytosterol</strong> composition should conta<strong>in</strong><br />

ma<strong>in</strong>ly sitosterol esters with low campesterol ester<br />

<strong>content</strong>, because apparently campesterol esters result<br />

<strong>in</strong> similar changes, when reduction <strong>of</strong> serum<br />

cholesterol level is concerned, but at <strong>the</strong> same time, <strong>in</strong><br />

contrast to sitosterol esters, <strong>the</strong>y <strong>in</strong>crease <strong>the</strong>ir own<br />

absorption. His second suggestion for oil, which<br />

would be preferable for preparation <strong>of</strong> functional food,<br />

was that it should be rich with stanols, especially<br />

sitostanol, esterified with polyunsaturated fatty acids.<br />

S<strong>in</strong>ce phytostanols are less abundant <strong>in</strong> plants than<br />

<strong>phytosterol</strong>s, <strong>in</strong> order to produce esterified<br />

phytostanols, <strong>the</strong> f<strong>in</strong>al food price will <strong>in</strong>crease.<br />

Result<br />

Plant sterols, also called <strong>phytosterol</strong>s, occur as organic<br />

compounds <strong>and</strong> essential constituents <strong>of</strong> cell<br />

membranes <strong>in</strong> all plant oils. Recently <strong>in</strong>creased<br />

<strong>in</strong>terest <strong>in</strong> <strong>phytosterol</strong>s lies <strong>in</strong> <strong>the</strong>ir potential to reduce<br />

plasma low-density lipoprote<strong>in</strong> cholesterol level,<br />

decreas<strong>in</strong>g coronary mortality <strong>and</strong> <strong>the</strong>refore act<strong>in</strong>g as<br />

naturally preventive dietary product. High<br />

expectations have already been put forward regard<strong>in</strong>g<br />

<strong>phytosterol</strong> analysis <strong>and</strong> traditional plant-breed<strong>in</strong>g<br />

applications <strong>in</strong> develop<strong>in</strong>g improved cultivars with<br />

desirable <strong>phytosterol</strong> composition <strong>and</strong> <strong>in</strong>creased<br />

<strong>content</strong>.<br />

Phytosterols occur <strong>in</strong> relatively high concentration<br />

<strong>in</strong> <strong>the</strong> seeds <strong>of</strong> <strong>oilseed</strong> <strong>rape</strong> (Brassica napus L.).<br />

However, little is known about genetic variation <strong>of</strong><br />

<strong>phytosterol</strong>s <strong>and</strong> almost no data are available <strong>of</strong> <strong>the</strong><br />

impact <strong>of</strong> geographic location <strong>and</strong> agricultural<br />

practices on <strong>the</strong> <strong>content</strong> <strong>and</strong> composition <strong>of</strong><br />

<strong>phytosterol</strong>s <strong>in</strong> <strong>rape</strong>seed. To improve <strong>the</strong> phtosterol<br />

composition must be a major breed<strong>in</strong>g aim for a high<br />

quality vegatable oil production.<br />

References<br />

Abidi SL, List GR <strong>and</strong> Rennick KA. Effect <strong>of</strong> genetic<br />

modification on <strong>the</strong> distribution <strong>of</strong> m<strong>in</strong>or constituents <strong>in</strong><br />

canola oil. <strong>Journal</strong> <strong>of</strong> American Oil Chemists’ Society,<br />

76: 463-467, 1999.<br />

Appelqvist LAD, Kornfeldt, AK <strong>and</strong> Wennerholm JE.<br />

<strong>Sterols</strong> <strong>and</strong> steryl esters <strong>in</strong> some brassica <strong>and</strong> S<strong>in</strong>apis<br />

Seeds. Phytochemistry, 20: 207-210, 1981.<br />

Becker HC, Löptien H <strong>and</strong> Röbbelen G. Breed<strong>in</strong>g: An<br />

O v e r v i e w. In: Developments <strong>in</strong> Plant Genetics <strong>and</strong><br />

Breed<strong>in</strong>g, 4: Biology <strong>of</strong> Brassica coenospecies. Gomez-<br />

Campo C. (ed.), 13: 413-449, 1999.<br />

Benveniste P. Sterol Metabolism. American Society <strong>of</strong> Plant<br />

Biologists, The Arabidopsis Book 1–31, 2002.<br />

Dutta CP <strong>and</strong> Normen L. Capillary column gas-liquid


chromatographic separation <strong>of</strong> 5-unsaturated <strong>and</strong><br />

saturated <strong>phytosterol</strong>s. <strong>Journal</strong> <strong>of</strong> Chromatography A,<br />

816: 177-184, 1998.<br />

FAO Food <strong>and</strong> Agriculture Organisation <strong>of</strong> <strong>the</strong> United<br />

Nations (Site, visited last time <strong>in</strong> April 2004). Food<br />

outlook – global Information <strong>and</strong> early warn<strong>in</strong>g System<br />

on food <strong>and</strong> agriculture. Available at:<br />

h t t p : / / w w w. f a o . o rg / Wa i c e n t / f a o i n f o / e c o n o m i c / g i e w s / e n g<br />

lish/fo/<strong>in</strong>dex.htm<br />

Gomez-Campo C. Taxonomy. In: Developments <strong>in</strong> Plant<br />

Genetics <strong>and</strong> Breed<strong>in</strong>g, 4: Biology <strong>of</strong> B r a s s i c a<br />

Coenospecies. Gomez-Campo C. (ed.), 1: 413-449, 1999.<br />

Gordon MH <strong>and</strong> Miller LAD Development <strong>of</strong> steryl ester<br />

analysis for <strong>the</strong> detection <strong>of</strong> admixtures <strong>of</strong> vegetable<br />

oils. <strong>Journal</strong> <strong>of</strong> American Oil Chemists’Society 74: 505-<br />

510, 1997.<br />

Grunwald, C. (1980) Steroids. In: Encyclopedia <strong>of</strong> Plant<br />

Physiology, Pirson, A. <strong>and</strong> Zimmermann, M.H. (eds.), 8:<br />

221-239, 1980.<br />

Gyll<strong>in</strong>g H, Radhakrishnan R <strong>and</strong> Miett<strong>in</strong>en TA. Reduction<br />

<strong>of</strong> serum cholesterol <strong>in</strong> postmenopausal women with<br />

previous myocardial <strong>in</strong>farction <strong>and</strong> cholesterol<br />

malabsorption <strong>in</strong>duced by dietary sitostanol ester<br />

margar<strong>in</strong>e. Circulation, 96: 4226-4231, 1997.<br />

Hartmann MA. Plant sterols <strong>and</strong> membrane environment.<br />

Trends <strong>in</strong> Plant Science , 3: 170-175, 1998.<br />

IUPAC, (Recommendations from 1989; site, visited last time<br />

<strong>in</strong> February 2004) The Nomenclature <strong>of</strong> Steroids,<br />

International Union <strong>of</strong> Pure <strong>and</strong> Applied Chemistry <strong>and</strong><br />

International Union <strong>of</strong> Biochemistry <strong>and</strong> Molecular<br />

B i o l o g y. Available at: http://www. c h e m . q m u l . a c . u k<br />

/iupac/steroid/<br />

Jones JHP, Ntanios FY, Rae<strong>in</strong>i-Sarjaz M <strong>and</strong> Vanstone CA.<br />

Cholesterol-lower<strong>in</strong>g Efficacy <strong>of</strong> a sitostanol-conta<strong>in</strong><strong>in</strong>g<br />

<strong>phytosterol</strong> mixture with a prudent diet <strong>in</strong><br />

hyperlipidemic men. American <strong>Journal</strong> <strong>of</strong> Cl<strong>in</strong>ical<br />

Nutrition, 69: 1144-1150, 1999.<br />

Kimber DS <strong>and</strong> McGregor DI. The species <strong>and</strong> <strong>the</strong>ir orig<strong>in</strong>,<br />

cultivation <strong>and</strong> world production. In: Brassica Oilseeds:<br />

Production <strong>and</strong> Utilization. Kimber, D.S. <strong>and</strong> McGregor<br />

D.I. (eds.), 1:1-7, 1995.<br />

Kyoto Encyclopedia <strong>of</strong> Genes <strong>and</strong> Genomes, (Site, visited<br />

last time <strong>in</strong> June 2004) Bio<strong>in</strong>formatics Center, Institute<br />

for Chemical Research, Kyoto University. Available at:<br />

http://www.genome.ad.jp/<br />

Law M. Plant sterol <strong>and</strong> stanol margar<strong>in</strong>es <strong>and</strong> health.<br />

British Medical <strong>Journal</strong> , 320: 861-864, 2000.<br />

L<strong>in</strong>dsey K, Pullen ML <strong>and</strong> Topp<strong>in</strong>g JF. Importance <strong>of</strong> plant<br />

sterols <strong>in</strong> pattern formation <strong>and</strong> hormone signall<strong>in</strong>g.<br />

Trends <strong>in</strong> Plant Science , 8: 1360-1385, 2003.<br />

Määttä K, Lampi AM, Petterson J Fogelfors BM, Piironen V<br />

<strong>and</strong> Kamal-Eld<strong>in</strong> A. Phytosterol <strong>content</strong> <strong>in</strong> seven oat<br />

cultivars grown at three locations <strong>in</strong> Sweden. <strong>Journal</strong> o f<br />

<strong>the</strong> Science <strong>of</strong> Food <strong>and</strong> A g r i c u l t u e, r 79: 1021-1027, 1999.<br />

Miett<strong>in</strong>en TA, Puska P, Gyll<strong>in</strong>g H, Vanhanen H <strong>and</strong><br />

<strong>Sterols</strong> <strong>and</strong> <strong>phytosterol</strong>s <strong>in</strong> <strong>oilseed</strong> <strong>rape</strong> 79<br />

Vartia<strong>in</strong>en H. Reduction <strong>of</strong> serum cholesterol with<br />

sitostanol-Ester margar<strong>in</strong>e <strong>in</strong> a mildly<br />

hypercholesterolemic Population. The New Engl<strong>and</strong><br />

<strong>Journal</strong> <strong>of</strong> Medic<strong>in</strong>e 333: 1308-1312, 1995.<br />

Miett<strong>in</strong>en TA. Phytosterols-what plant breeders should focus<br />

on. <strong>Journal</strong> <strong>of</strong> <strong>the</strong> Science <strong>of</strong> Food <strong>and</strong> A g r i c u l t u re, 81:<br />

895-903, 2001.<br />

Nes WD Multiple Roles for Plant <strong>Sterols</strong>. In: T h e<br />

Metabolism, Structure <strong>and</strong> Function <strong>of</strong> Plant Lipids.<br />

Stumpf, P.K., Mudd, J.B. <strong>and</strong> Nes, W.D. (eds.), 3-9, 1987.<br />

Niss<strong>in</strong>en M, Gyll<strong>in</strong>g H, Vuoristo M <strong>and</strong> Miett<strong>in</strong>en TA.<br />

Micellar distribution <strong>of</strong> cholesterol <strong>and</strong> <strong>phytosterol</strong>s<br />

after duodenal plant stanol ester <strong>in</strong>fusion. A m e r i c a n<br />

<strong>Journal</strong> <strong>of</strong> Physiology - Gastro<strong>in</strong>test<strong>in</strong>al <strong>and</strong> Liver<br />

P h y s i o l o g y, 282: 1009-1015, 2002.<br />

Normen L, Johnsson M, Andersson H, van Gameren Y <strong>and</strong><br />

Dutta CP. Plant sterols <strong>in</strong> vegetables <strong>and</strong> fruits<br />

commonly consumed <strong>in</strong> Sweden. E u ropean <strong>Journal</strong> <strong>of</strong><br />

N u t r i t i o n, 38: 84-89, 1999.<br />

Normen AL, Brants, HAM, Voorrips LE, Andersson HA,<br />

van den Br<strong>and</strong>t PA <strong>and</strong> Goldbohm AR. Plant sterol<br />

<strong>in</strong>takes <strong>and</strong> colorectal cancer risk <strong>in</strong> <strong>the</strong> Ne<strong>the</strong>rl<strong>and</strong>s<br />

cohort study on diet <strong>and</strong> cancer. American <strong>Journal</strong> <strong>of</strong><br />

Cl<strong>in</strong>ical Nutrition, 74: 141-148, 2001.<br />

Piironen V, L<strong>in</strong>dsay DG, Miett<strong>in</strong>en TA, Toivo J <strong>and</strong> Lampi<br />

AM. Review Plant sterols: Biosyn<strong>the</strong>sis, biological<br />

function <strong>and</strong> <strong>the</strong>ir importance to human nutrition.<br />

<strong>Journal</strong> <strong>of</strong> <strong>the</strong> Science <strong>of</strong> Food <strong>and</strong> A g r i c u l t u re, 80: 939-<br />

966, 2000.<br />

Piironen V, Toivo J <strong>and</strong> Lampi AM. Plant sterols <strong>in</strong> cereals<br />

<strong>and</strong> cereal products. C e real Chemistry, 79: 148-154,<br />

2002.<br />

Piironen V, Toivo J Puupponen-Pimiä R <strong>and</strong> Lampi AM.<br />

Plant sterols <strong>in</strong> vegetables, fruits <strong>and</strong> berries. <strong>Journal</strong> o f<br />

<strong>the</strong> Science <strong>of</strong> Food <strong>and</strong> A g r i c u l t u re, 83: 330-337, 2003.<br />

Rehm S <strong>and</strong> Espig G. The cultivated plants <strong>of</strong> <strong>the</strong> tropics <strong>and</strong><br />

subtropics. Institute <strong>of</strong> A g ronomy <strong>in</strong> <strong>the</strong> Tro p i c s<br />

University <strong>of</strong> Gött<strong>in</strong>gen, Oil Plants: 76, 1991.<br />

Salo P, Wester I <strong>and</strong> Hopia A.Phytosterols. In: Lipids for<br />

Functional Foods <strong>and</strong> Nutraceuticals. Gunstone, FD.<br />

(ed.), 7:183-224, 2003.<br />

Trautwe<strong>in</strong> EA, Duchateau, G, L<strong>in</strong>, Y, Melcnikov, SM.<br />

Molhuizen H <strong>and</strong> Ntanios, FY. Proposed mechanisms <strong>of</strong><br />

cholesterol-lower<strong>in</strong>g action <strong>of</strong> plant sterols E u ro p e a n<br />

<strong>Journal</strong> <strong>of</strong> Lipid Science <strong>and</strong> Te c h n o l o g y, 105: 171-185, 2003.<br />

UFOP Union zur Förderung von Ol- und Prote<strong>in</strong>pflanzen<br />

(Site, visited last time <strong>in</strong> May 2004) Biodiesel<br />

F l o w e r p o w e r. Dieter Bockey (ed.) 2. Available at:<br />

w w w. u f o p . d e<br />

Willmann MR. <strong>Sterols</strong> as regulators <strong>of</strong> plant embryogenesis.<br />

Trends <strong>in</strong> Plant Science, <strong>Journal</strong> Club , 5(10):416, 2000.

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