Indonesian Medicinal Plants. XIV. Characterization of 3'-O-Caffeoylsweroside, a new secoiridoid glucoside, and kelampayosides A and B, two new phenolic apioglucosides, from the bark of Anthocephalus chinensis (Rubiaceae).

A new secoiridoid glucoside named 3'-O-caffeoylsweroside (1), and two new phenolic apioglucosides, named kelampayoside A (4) and kelampayoside B (6), together with eleven known compounds (five iridoids and six alkaloids), were isolated from the bark of Anthocephalus chinensis (Rubiaceae), an Indonesian medicinal plant from Sumatra Island, Indonesia. The chemical structures of 1, 4 and 6 have been elucidated respectively as 3'-O-caffeoylsweroside (1), antiarol 1-O-beta-D-apiofuranosyl (1 --> 6)-beta-D-glucopyranoside (4), and antiarol 1-O-beta-D-5"-O-caffeoylapiofuransoyl (1 --> 6)-beta-D-glucopyranoside (6) on the bases of their chemical and physiochemical properties. Among fourteen constituents characterized, cadambine (13), one of the major indole alkaloid constituents of A. chinensis, was shown to exhibit moderate growth-inhibitory activity against the malarial parasite Plasmodium falciparum (a chloroquine-resistant K1 strain) cultured in human erythrocytes.