Evaluation of the Inhibitory Effect on α-glucosidase and α-amylase Enzymes of Triterpenes Isolated from Commelina diffusa Burm.f.

By using column chromatography and thin layer chromatography, three triterpene compounds were isolated from the n-hexane fraction of the methanol extract of Commelina diffusa, including corosolic acid (1), 3α-acetyl-20S,24S-epoxydammarane-25-ol (2) and 11-oxo-α-amyrin acetate (3). The structures of the isolated compounds were determined by spectroscopic methods and compared with references. This is the first time compounds 2 and 3 have been isolated from the genus Commelina. For enzyme inhibition assays, among three tested compounds, compound 1 had the highest inhibitory effect on α-glucosidase enzyme with an IC50 value of 93.68 ± 4.1 µg/mL while compound 2 showed the strongest ability to inhibit α-amylase enzyme with an IC50 value of 100.64 ± 3.6 µg/mL. Meanwhile, the IC50 values of positive control acarbose in these two assays were 135.73 ± 1.8 µg/mL against α-glucosidase enzyme and 83.33 ± 2.0 µg/mL against α-amylase enzyme, respectively.