Medicinal Plants Classification Biosynthesis and ... - Index of

180
Vandana Gulati, Ian H. Harding and Enzo A. Palombo
Glycosides: Chrysophanol-8-O-β-D-glucopyranoside and chrysophanol anthraquinones
from Rhubarb rhizome showed good antidiabetic properties (70). Rhaponticin and rhein
isolated from Rhei Rhizoma improved glucose tolerance by inhibiting α-glucoamylase
activity, increasing insulin sensitivity and delaying carbohydrate digestion in STZ-induced
diabetic mice. In vitro studies also showed improvement in insulin sensitivity (71).
Dolichandroside A, a new phenylpropanoid glycoside isolated from Dolichandrone falcate
Seem, is a novel α-glucosidase inhibitor, while saponarin II, isolated from the same plant, is
very effective α-glucosidase inhibitor having the same potency as acarbose (72). Dendrobium
chrysotoxum Lindl. is a traditional Chinese herb. Polysaccharides isolated from this plant
have been found to significantly reduce blood glucose levels in alloxan-induced diabetic mice
as well as having good antioxidant activity (73). Lupinoside isolated from Pureria tuberosa
helps in prevention of palmitate-induced impairment of insulin (74).
A C
Figure 2. Structures of six groups of flavonoids
Alkaloids: Adhatoda vasica Nees, a common Indian Ayurvedic plant, was screened for
activity against α-glucosidase and α-amylase. The aqueous methanolic extract of its leaves
showed high sucrase inhibitory activity and enzyme assay-guided fractionation led to
discovery of vasicine and vasicinol. Both the compounds showed high sucrase inhibitory
activity by reversible inhibition of sucrose hydrolyzing activity of rat intestinal α-glucosidase.
The enzymatic inhibition of α-glucosidase was studied for the first time in this plant,
although it is well known for other pharmacological activities (75). Two new active
B