α-Glucosidase Inhibitory Activity of Compounds Isolated from the ZC07 Fraction of Zingiber cassumunar Roxb. Rhizomes

Abstract

Gừng dại (Zingiber purpureum Roscoe ≡ Z. cassumunar Roxb.), a member of the ginger family (Zingiberaceae), is found in Southeast Asian countries, including Vietnam. In the folk medicine of these countries, the rhizome of wild ginger is used for pain relief, anti-inflammation, digestive support, and the treatment of skin diseases. This study reports the isolation and structural elucidation of compounds from the ZC07 fraction of Z. cassumunar rhizomes collected in An Giang Province. The results revealed one monoterpenoid (p-menthane-1,2,4-triol (1)), two phenylbutenoid compounds (cassumunol F (2) and cassumunol H (3)), and three phenolic compounds  (veratric acid (4), asaraldehyde (5), and veratraldehyde (6)). The structures of the compounds were clarified based on analyses of 1D and 2D NMR spectra in combination with comparisons to the literature. Among them, compounds 1 and 6 are reported for the first time in this species. Bioactivity assays showed that all isolated compounds exhibited certain levels of α-glucosidase inhibitory activity at a concentration of 250 μM. Notably, compounds 1 and 2 demonstrated inhibitory effects comparable to the positive control acarbose, with values of 162.8 and 136.4 μM, respectively, while the remaining compounds showed weak inhibition. This study adds to the database of natural-product structures and the α-glucosidase inhibitory activities of these compounds.