Medicinal Plants Classification Biosynthesis and ... - Index of

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Vandana Gulati, Ian H. Harding and Enzo A. Palombo
from three different parts and fermented with three different fungal strains was also shown to
possess significant α-glucosidase inhibitory activity. Douchi fermentatied with A. oryzae had
strong inhibition as compared to the same food fermented with other fungi like A. elegans
and R. arrhizus (35). Genistein, an isoflavone isolated from soybeans is a potent αglucosidase
inhibitor (36).
The anti-diabetic potential of ten plants, agrimony (Agrimony eupatoria), coriander
(Coriandrum sativum), eucalyptus (Eucalyptus globulus), juniper (Juniperus communis),
Lucerne (Medicago sativa), avocado (Persea americana), elder (Sambucus nigra), nettle
(Urtica diocia), mushroom (Agaricus campestris) and mistletoe (Viscum album) were
evaluated by an in vitro dialysis model of glucose movement. The glucose movement was
decreased by more than 50% by agrimony and avocado. Mushroom, coriander, eucalyptus,
juniper, lucerne, and mistletoe were less effective. Nettle and elder extracts did not
significantly decrease glucose diffusion. The effects of agrimony, avocado, coriander and
mushroom extracts were found to be concentration dependent. It was concluded that
agrimony and avocado have the ability to inhibit glucose diffusion using an in vitro model of
glucose absorption and represented potential dietary supplements that may be useful for
allowing flexibility in meal planning for management of Type II diabetes (37). In an in vivo
study, the aqueous and methanolic leaf extracts of avocado resulted in a reduction in plasma
glucose level, total cholesterol and LDL-cholesterol levels in albino rats (38). The methanolic
extract of the flowering part of pomegranate (Punica granatum Linn.) was evaluated by in
vivo and in vitro diabetes assays. The extract was shown to decrease plasma glucose levels
and possess potent inhibitory activity against α-glucosidase. It was suggested that it improved
postprandial hyperglycemia during treatment of Type II diabetes and obesity (39). The
extracts of strawberries (Fragaria ananasia) and raspberries (Rubus idaeus L. variety Glen
Ample) significantly inhibited salivary as well as pancreatic α-amylase enzyme. Blueberries
(Vaccinium corymbosum L. variety Berkley), blackcurrant (Ribes nigrum L. variety Ben
Lomond), red cabbage, red wine, red grape and green teas were also shown to be effective
and it was found that the activities were due to soluble tannins in these fruit extracts.
Blueberries and blackcurrants were shown to be more active against α-glucosidase and the
activity was based on their anthocyanin content. The inhibitory activity of anthocyanins and
tannins was proved by removing the anthocyanin and tannin fractions from the above
samples, and it was reported that tannins were related to amylase inhibition while
anthocyanins were responsible for glucosidase inhibition (40).
In another study, a new natural α-glucosidase inhibitor from red wine vinegar (made by
the fermentation of storage root paste of purple fleshed sweet potato, Ipomea batata) was
identified as caffeoylsophorose. The compound was tested against α-glucosidase and studied
in Sprague Dawley rats and the experiments demonstrated that caffeoylsophorose suppressed
the increased postprandial blood glucose level achieved by inhibition of maltase (41).
Clonal herbs of family Lamiaceae were evaluated for the management of diabetes and
hypertension. Water extracts of clonal lines of rosemary Rosmarinus officinalis, clones
(Rosemary LA, Rosemary RoK-2 and Rosemary Ro-6), lemon balm (Melissa officinalis),
sage (Salvia officinalis), chocolate mint (Mentha piperata) and oregano (Origanum vulgare,
clone Oregano Go-19-2) were screened using enzymatic inhibition assays of α-glucosidase,
α-amylase and ACE-I. Oregano showed the greatest α-glucosidase inhibition activity,