Abstract
Phytochemical investigation of the semi-parasitic plant, Plicosepalus curviflorus (Loranthaceae) growing in Saudi Arabia resulted in the isolation of a new catechin-gallic acid derivative of inositol, plicosepalin A (1) [(+) catechin-4'-O-(1 ''-O-galloyl-5 ''-O-methyl)-myoinositol], along with seven known compounds: methyl gallate (2), catechin (3), quercetin (4), gallic acid (5), lupeol (6), beta-sitosterol (7), and ursolic acid (8). Their structures were elucidated on the basis of spectroscopic analyses, including HRESIMS, ESIMS, H-1 and C-13 NMR, HSQC, and HMBC, as well as comparison with reported data. The antioxidant and antimicrobial activities of 1 were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the disc diffusion assay, respectively. Compound 1 exhibited potent free radical scavenging activity with an IC50 value of 9.0 +/- 0.27 mu M. Moreover, significant activities against Staphylococcus aureus and Bacillus subtilis were recorded.