Enzymes inhibitors from natural sources with antidiabetic activity: A review

Natural products have been extensively investigated for antidiabetic therapy. Many of the natural products have direct or indirect effect in diabetes pathways as enzyme inhibitors. The most involved mechanisms are inhibition of intestinal alpha-glucosidase and alpha-amylase, lens aldose reductase, oxidative stress protection, inhibition of formation of advanced glycation end products, inhibition of aldose reductase, lowering plasma glucose levels, altering enzyme activity of hexokinases and glucose-6-phosphate, synthesizing and releasing of insulin, postprandial hyperglycemia inhibition, stimulation of GLUT-4, decreasing activity of G6P, lowering the level of skeletal hexokinases, etc. The following medicinal plants products or extracts showed promising effects as enzyme inhibitors: Abelmoschus moschatus, Alangium salvifolium, Azadirachta indica, Bidens pilosa, Boerhaavia diffusa, Capsicum frutescens, Cassia alata, Eclipta alba, Embellica officinalis, Ficus carica, Gentiana Olivier, Glycyrrhiza glabra, Gymnema sylvestre, Hordeum vulgare, Ipomoea aquatica, Juniperus communis, Mangifera indica, Momordica charantia, Ocimum sanctum, Punica granatum, and Zingiber officinale. Some of the group of phytochemicals isolated with enzyme inhibition activities are Alkaloids, sesquiterpene and saponins, polysaccharides, flavonoids, dietary fibers, ferulic acid, tannins, limonene, and oleuropeoside. This review will provide very useful material to enhance the efficiency of rational antidiabetic drug design.