International Congress BIOLOGICAL PRODUCTS - Gruppo di ...

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DETERMINATION OF PHENOLIC COMPOUNDS IN EXPERIMENTAL WINES SUBJECTED TO
DIFFERENT PESTICIDES TREATMENTS
G. L .La Torre, T. M. Pellicanò, D.Pollicino, M. Alfa, G.mo Dugo
Università degli Studi di Messina; Dip.to di Chimica Organica e Biolog ica
INTRODUCTION
Wine is a complex fluid; it contains water, sugars, acids, alcohols and a wide range of phenolic compounds. The
phenolics can be derived from grapes and wood, or they can be metabolites from yeasts. Phenolics occur
naturally in various families of plants, but grapes and related products are considered one of the most important
dietary sources of these substances (1, 2). Phenolic compounds are an important group of substances that
contribute to several sensorial characteristics such as colour, flavour, astringency and hardness of wine.
Furthermore, these compounds are important in food hygiene because of their bactericidal effects and,
consequently, they constitute an interesting index for evaluating the quality of a wine (3 - 5). Some researchers
suggest that a regular consumption of a moderate quantity of wine, especially red (6-8), is therapeutic for human
health. This protective effect has been associated with an increase in the plasma of the level of high-density
lipoprotein (HDL)-cholesterol and with a decrease of platelet activity, because of the effect of ethanol and
polyphenolic components (9). Epidemiological studies have shown that a moderate wine consumption helps to
prevent the development of coronary heart disease (10,11).
The major molecules responsibles for this physiologic protection are phenolic compounds such as resveratrol
and flavonoids. Moreover, it has been reported that resveratrol, quercetin and other polyphenolics are cancer
chemo-preventive agents, since through the inhibition of cyclooxygenase they restrain cellular events associated
with tumour initiation, promotion and progression, and stimulate quinone reductase – an enzyme that detoxifies
carcinogens (12,13). In recent years, interest has been focused on resveratrol (3,5,4’-trihydroxystilbene), a
phytoalexin produced by the plant as a defence response to some exogenous stimuli, such as ultraviolet radiation,
chemical stressor and, particularly, microbial infections (15). It is well-known that resveratrol is present in the
chemical form of cis- and trans-resveratrol and of cis- and trans-piceid ( β-glucosides of resveratrol) (16). The
presence of resveratrol has been detected in numerous types of wines, originating from various countries (USA,
France, Italy, Spain, Japan), and large variations in its content are reported. They depend on grape cultivar,
geographic origin, wine type, Botrytis infection and enological practices. Generally, many authors found that
higher contents of trans-resveratrol (0.2 - 13 mg/L) are usually present in red wines that have had a prolonged
contact between the must and skins, whereas lower concentrations (0.1 - 0.8 mg/L) are usually present in white
wine (17, 18). In rosé wines the levels of resveratrol monomers were between white and red wines (18). About
β-glucosides of resveratrol, no proportionality between the levels of cis- and trans-resveratrol and their
glucosides were reported (19), whereas piceid concentrations from 0.3 mg/L to 9 mg/L in red wines and from 0.1
mg/L to 2.2 mg/L in white wines have been detected (14). Studies on resveratrol content in wines are numerous
(20-24); they are often focussed on the different grape cultivars and associated with the identification of
polyphenolic compounds, of potential biological activities, such as quercetin, myricetin, etc. The phenolic
compounds are secondary plant metabolites that are contained within the skin, seed, and flesh of grapes and are
extracted into wines (especially red) during the process of vinification. The types and concentrations of the
phenolic compounds in wine may depend on a number of factors: grape variety and ripening stage, soil and
climatic conditions. Moreover, the processes of viticulture and vinification, which vary between countries,
regions and wine-makers, determine the content and profile of phenolic compounds in wine (14). The
concentration of phenolic compounds is marked by temperature, so places with high temperatures and drier
conditions disfavour the presence of these compounds in wines.(16)
The purpose of this study was to determine the polyphenolic compounds (resveratrol, piceid, and flavonoids) in
wines from three different Italian regions, obtained from grapes (Sangiovese, Fiano d’Avellino, Inzolia-
Caricante (50/50)) treated with different pesticides and to investigate the probable influence of the different
treatments on the quality of the wines.
MATERIALS AND METHODS
Chemicals and materials
trans-Resveratrol was purchased from Sigma Chemical Co. Stock solution of cis-resveratrol was produced by UV
irradiation of trans-resveratrol in methanol for 30 min at 254 nm. Solid-phase extraction (SPE) cartridges were
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