Evaluation of antidiabetic, anti-inflammatory and LDL oxidation inhibitory potential of Alpinia galanga and Alpinia calcarata-An in vitro study

Alpinia galanga and Alpinia calcarata are two important aromatic medicinal plants belonging to the family Zingiberaceae. In the present study, dried rhizomes of A. galanga and A. calcarata were extracted with water and then fractionated with different solvents. Among the various solvent fractions, ethyl acetate (EA) fraction of both plants showed high polyphenolic content with better antioxidant activity. This polyphenol rich EA fraction was also screened for its antidiabetic and anti-inflammatory potential using in vitro assays. Results showed that EA fractions of these two plants had significant antihyperglycemic activity by inhibiting carbohydrate digesting enzymes (α-amylase and α-glucosidase) and by inhibiting glycation reaction. Inhibitory potential of EA fractions of both plants against protein denaturation and xanthine oxidase validates their anti-inflammatory potential. Moreover, EA fractions also exhibited significant LDL oxidation inhibition. The observed antidiabetic and anti-inflammatory properties of A. galanga and A. calcarata could be due to the synergic effect of polyphenols such as gallic acid and ellagic acid as well as bioactive alkaloid, berberine.