Phenolic Compounds from the Whole Plants of Gentiana rhodantha (Gentianaceae)

Gentiana rhodantha FRANCH. ex HEMSL. (Gentianaceae), an annual herb widely distributed in the southwest of China, has been medicinally used for the treatment of inflammation, cholecystitis, and tuberculosis by the local people of its growing areas. Chemical investigation on the whole plants led to the identification of eight new phenolic compounds, rhodanthenones A-D (1-4, resp.), apigenin 7-Oglucopyranosyl-(1 -> 3)-glucopyranosyl-(1 -> 3)-glucopyranoside (5), 1,2-dihydroxy-4-methoxybenzene 1-O-alpha-L-rhamnopyranosyl-(1 -> 6)-beta-D-glucopyranoside (6), 1,2-dihydroxy-4,6-dimethoxybenzene 1-O-alpha-L-rhamnopyranosyl-(1 -> 6)-beta-D-glucopyranoside (7), and methyl 2-O-beta-D-glucopyranosyl-2,4,6-trihydroxybenzoate (8), together with eleven known compounds, 9-19. Their structures were determined on the basis of detailed spectroscopic analyses and chemical methods. Acetylcholinesterase (AChE) inhibition and cytotoxicity tests against five human cancer cell lines showed that only rhodanthenone D (4) and mangiferin (12) exhibited 18.4 and 13.4% of AChE inhibitory effects at a concentration of 10(-4) M, respectively, while compounds 1-5 and the known xanthones lancerin (11), mangiferin (12), and neomangiferin (13) displayed no cytotoxicity at a concentration of 40 mu M.