Anti-diabetic Effect of Major Compounds from Commelina diffusa

Although Commelina diffusa Burm.f., Commelinaceae, has been proven to exhibit many pharmacological activities, the scientific evidence for its antihyperglycemic activities and active substances is still limited. This present study aims to evaluate the in vitro antidiabetic ability of C. diffusa using α-glucosidase and α-amylase inhibitory assays and isolate its pure compounds with enzymatic inhibitory effects. The ethyl acetate fraction, with the most potent hypoglycemic activity, was chosen to separate and purify six known compounds: 4-hydroxybenzoic acid, methyl gallate, lyratol F, N-trans -feruloyltyramine, N-trans - p -coumaroyl-3′,4′-dihydroxyphenylethylamine, and 1,2-dihydro-6,8-dimethoxy-7-hydroxy-1-(3,5-dimethoxy-4-hydroxyphenyl)- N 1 , N 2 -bis-[2-(4-hydroxyphenyl)ethyl]-2,3-naphthalene dicarboxamide ( 6 ). Furthermore, the antihyperglycemic effect of the isolated compounds was also evaluated in vitro on α-glucosidase and α-amylase enzymes. Compound 6 exhibited the most potent inhibitory activity against both tested enzymes with values of 61.37 ± 0.83 µM in the α-glucosidase assay and 38.23 ± 1.04 µM in the α-amylase assay. These values were much higher than those of positive control (acarbose IC 50 210.43 ± 2.78 and 129.19 ± 3.13 µM, respectively). This is the first report on the antidiabetic capacity of C. diffusa and its hypoglycemic pure compounds. Our findings suggested that C. diffusa might be a promising source of antidiabetic agents. Graphical Abstract