Abstract:
Phytochemical investigation of the methanol extract from Dendrobium formosum (Orchidaceae) resulted in the isolation of twelve known compounds, which included two phenanthrenes (confusarin, nudol), five dihydrophenanthrenes (hircinol, erianthridin, lusianthridin, coelonin, 2,5,7-trihydroxy-4-methoxy-9,10-dihydrophenanthrene), a dihydrophenanthrenequinone (5-methoxy-7-hydroxy-9,10-dihydro-1,4-phenanthrenequinone), three bibenzyls (gigantol, batatasin III, moscatilin), and a phenylpropanoid (dihydroconiferyl dihydro-p-coumarate). These structures were determined by analysis of their NMR and HRS-ESI-MS data. The isolates were evaluated for α-glucosidase and lipase inhibitory activities. Among the isolates, 5-methoxy-7-hydroxy-9,10-dihydro-1,4-phenanthrenequinone showed the highest α-glucosidase and lipase inhibitory effects with IC50 values of 126.88 µM and 69.45 µM, respectively. An enzyme kinetics study conducted by the Lineweaver-Burk plot method revealed that 5-methoxy-7-hydroxy-9,10-dihydro-1,4-phenanthrenequinone was a non-competitive inhibitor of α-glucosidase and lipase enzymes.
