Three novel constituents from curculigo capitulata and revision of C-2 stereochemistry in nyasicoside
Continuing study of the constituents of the rhizomes of Curculigo capitulata provided three novel compounds, including two norlignan glucosides, curcapicycloside (2) and (1S,2R)-O-methylnyasicoside (3), and a phenanthrofuran, curcapital (9). The former two compounds were characterized as their tetra-O-methyl derivatives. Compound 2 possesses a glucosyl-fused skeleton with 1R,2R configuration. Biogenetic consideration led to a revision of the previously assigned 2S configuration of nyasicoside (1) to 2R, which was confirmed by NOE studies of the acetonide of its tetra-O-methyl derivative. The 2R configuration in tetra-O-methyl-1-O-methyl curculigine (7a) and isocurculigine (8a) was also established by chemical correlation of the former with (1R, 2R)-tetra-O-methyl-1-O-methylnyasicoside (10a). Curcapital (9) represents the first natural product having a phenanthro[9,10, b]furan skeleton.
Chang
WL
School of Pharmacy, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Republic of China.
Chen
CH
Lee
SS