Medicinal Plants Classification Biosynthesis and ... - Index of

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Vandana Gulati, Ian H. Harding and Enzo A. Palombo
Ocimum album, Achyranthes aspera, Withania somnifera, Salacia oblonga, Equisetum
myriochaetum, Salacia oblonga Wall, Swertia chiraita, Swertia japonica, Aralia cachemirica
Decne., Cryptolepis Sanguinolenta, Ocimum sanctum Linn, Stevia rebaudiana Bertoni,
Cantharanthus roseus, Azadirachta indica, Mucuna pruriens, Eruka sativa, Opuntia
steptacantha, Lantana camara, Agrimony eupatoria L., Eucalyptus globules Labill,
Semecarpus anacardium Linn., Chamaemelum nobile, Salvia officinalis, Coscinium
fenestratum, Pterocarpus marsupium, Asparagus adscendens, Selaginella tamariscina
Beauv, Nelumbo nucifera, Phyllanthus amarus, Tinospora cardifolia, Acanthopanax
senticosus, Silybum marianum, Panax ginseng, Aesculus hippocastanum L., Kochia scoparia,
Salvia lavandifolia Vahl., Butea monosperma, Gymnema sylvestre, Acrocomia mexicana,
Pandanus odorus and Salicornia herbacea L. (19). An extract of pine bark and needle
showed inhibition against salivary α-amylase and yeast α-glucosidase enzymes and
significantly reduced postprandial glucose level (51). The astringent extract of chest nut skin
(52), extract of Pycnanthus angolensis fruits (53), ethanolic extract of Butea monosperma
(54), leaf extract of kiwi fruit (55), seed kernel of Syzigium cumini (56), leaves of guava,
Psidium guajava Linn. (57) have all shown good hypoglycemic potential.
Pytochemicals with Anti-Diabetic Activities
A number of bioactive compounds have been isolated from plants which are potent αglucosidase
and/or α-amylase inhibitors and show good antidiabetic properties. The main
phytochemicals with reported anti-diabetic activities were flavonoids, polyphenolic
compounds, tannins, glycosides, alkaloids and terpenoids. The active phytochemicals were
isolated, purified and scientifically validated for anti-diabetic action by in vitro or in vivo
experiments.
Flavonoids and Polyphenolic compounds: Luteolin isolated from Lonicera japonica,
amentoflavone isolated from the leaves of Ginkgo biloba, luteolin-7-O-glucoside isolated
from Salix gracilistyla and daidzein isolated from soybeans are all natural flavanoids which
showed strong inhibitory activity against α-glucosidase and α-amylase, with luteolin
exhibiting greater activity than acarbose (58). Similarly, hydnocarpin, luteolin and
isohydnocarpin isolated from acetone extracts of seed hulls of Hydnocarpus wightiana Blume
were screened against yeast α-glucosidase and it was found that luteolin showed the strongest
inhibitory activity; isohydnocarpin was also a potent inhibitor while hydnocarpin was a mild
inhibitor (59). Quercetin 3-O-β-D-xylopyranosyl (1″ → 2″ )-β-D-galactopyranoside and (-)lyoniresinol
3-O-β-D-glucopyranoside isolated from the leaves of Alstonia scholaris, also
called as Devil tree, is a traditional Thai medicinal plant. Quercetin 3-O-β-D-xylopyranosyl
(1″ → 2″ )-β-D-galactopyranoside was found to possess maltase inhibitory activity and (-)lyoniresinol
3-O-β-D-glucopyranoside showed significant inhibition against both the sucrase
and maltase activities of α-glucosidase (60).
Crude 50% methanolic extracts of rhizomes of Berginia ciliata, a Nepalese medicinal
plant used to treat several diseases, showed significant inhibitory activity against rat intestinal
α-glucosidase and porcine pancreatic α-amylase. This extract was fractionated for the