Kaempferol acetylrhamnosides from the rhizome of Dryopteris crassirhizoma and their inhibitory effects on three different activities of human immunodeficiency virus-1 reverse transcriptase

Three new kaempferol glycosides, called crassirhizomosides A (1), B (2) and C (3), were isolated from the rhizome of Dryopteris crassirhizoma (Aspidia ceae), together with the known kaempferol glycoside, sutchuenoside A (4). T he structures of 1-3 we re determined as kaempferol 3-alpha -L(2,4-di-O-ace tyl)rhamnopyranoside-7-alpha -L-rhamnopyranoside, kaempferol 3-alpha -L-(3, 4-di-O-acetyl)rhamnopyranoside-7-alpha -L-rhamnopyranoside-7-alpha -L-respe ctively, by chemical and spectroscopic means. Inhibitory effects of 1-4 and kaempferol on human immunodeficiency virus reverse transcriptase-associate d DNA polymerase (RNA-dependent DNA polymerase and DNA-dependent DNA polyme rase) and RNase H activities were investigated.