Cytotoxic alkaloids from the tuber of Stephania venosa
2001
Keawpradub, N.(Prince of Songkla Univ., Songkhla (Thailand). Faculty of Pharmaceutical Sciences. Dept. of Pharmacognosy and Pharmaceutical Botany) E-mail:kniwat@ratree.psu.ac.th | Itharat, A.(Prince of Songkla Univ., Songkhla (Thailand). Faculty of Pharmaceutical Sciences. Dept. of Pharmacognosy and Pharmaceutical Botany) | Tantikarnkul, A.(Prince of Songkla Univ., Songkhla (Thailand). Faculty of Pharmaceutical Sciences. Dept. of Pharmacognosy and Pharmaceutical Botany) | Rugleng, S.(Prince of Songkla Univ., Songkhla (Thailand). Faculty of Pharmaceutical Sciences. Dept. of Pharmacognosy and Pharmaceutical Botany) | Inruspong, P.(Prince of Songkla Univ., Songkhla (Thailand). Faculty of Pharmaceutical Sciences. Dept. of Pharmacognosy and Pharmaceutical Botany)
Water and ethanol extracts prepared from the tuber of Stephania venosa were assessed for cytotoxic activity against brine shrimp. Pronounced cytotoxic activity was exhibited by the ethanol extract with an LC sub(50) value of 90.8 micro g/ml. The water extract was about two times less active than the ethanol extract with an LC sub(50) value of 184.9 micro g/ml. The ethanol extract was further tested against human cancer cell line MCF-7 (breast adenocarcinoma) which was found to be cytotoxic with an IC sub(50) value of 11.6 micro g/ml. Activity-directed fractionation led to the isolation of three isoquinoline alkaloids, tetrahydropalmatine, crebanine and palmatine, from the most active fraction of the ethanol extract. Palmatine has been isolated for the first time from S. venosa. Structures of the alkaloids were determined by spectroscopic methods, particularly NMR techniques. Palmatine and crebanine were found to possess pronounced activity against MCF-7 with IC sub(50) values in the range of 5-6 micro g/ml. Crebanine and palmatine also exhibited cytotoxic activity against brine shrimp with LC sub(50) values of 29.6 and 74.4 micro g/ml, respectively. In marked contrast, tetrahydropalmatine was considerably less active than crebanine and palmatine. It is evident that the alkaloids crebanine and palmatine were mainly responsible for the observed activity of the extract, which could be used as biomarkers for cytotoxic activity of the tuber of S. venosa. The results lend some support to the use of the tuber of S. venosa in traditional medicine as a remedy for treating breast cancer.
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