Longiflorol, a bergenin α-d-apioside from the stem bark of Diospyros longiflora, and its antioxidant activity

Phytochemical investigation of the stem bark of Diospyros longiflora yielded longiflorol (1), a new bergenin α-d-apioside, together with bergenin (2) and five known compounds: lupeol (S1), betulin (S2), betulinic acid (S3), stigmasterol (S4) and stigmasterol glucoside (S5). Their structures were determined by one-dimensional (1D) and 2D nuclear magnetic resonance experiments along with electrospray ionization high-resolution mass spectrometry and extended density-functional theory calculations of chiroptical properties. Longiflorol (1) and bergenin (2) were evaluated for their DPPH (2,2-diphenyl-1-picrylhydrazyl) antioxidant activity, with the crude extract for comparison and ascorbic acid as standard. The results showed that the extract and 2 had good antioxidant activity, whereas 1 showed only moderate activity at high concentration (>2 mg mL−1).