Cytotoxic activity of hot water and ethanloic extracts of a poly-herbal preparation comprised of Nigella sativa, Hemidesmus indicus and Smilax glabra

Recently we have reported that a decoction (hot water extract) comprised of Nigella sativa (seeds), Hemidesmus indicus (roots) and Smilax glabra (rhizome) has a significant cytotoxic effect on human hepatoma cells (HepG2) and exerts protection against hepatocarcinogenic changes in rats [1–3]. The present study is a preliminary investigation to identify compounds responsible for the cytotoxic activity of this poly-herbal preparation. Hot water and ethanolic extracts of the poly-herbal preparation were tested for cytotoxicity on HepG2 cells using MTT and SRB assays. Concentrations of the extracts used varied between 300µg/ml and 4800µg/ml, and the cells were treated with each of these concentrations for 24, 48 and 72h. HPLC profiles of thymoquinone (a known cytotocxic compound of Nigella sativa) and the hot water and ethanolic extracts were obtained by application of a reversed phase linear gradient of 80% water in methanol to 100% methanol. Both extracts showed a time and dose dependent cytotoxicity as measured by MTT and SRB assays. The hot water extract had marginally higher activity at lower concentrations (<1200µg/ml). HPLC profiles showed the presence of both polar and non-polar compounds in the two extracts. A higher aggregation of polar compounds was observed in the hot water extract. Thymoquinone was present in the ethanolic but not in the hot water extract. Thus, compounds other than thymoquinone appear to mediate the cytotoxicity of the hot water extract of this poly-herbal preparation.

Acknowledgements: This work was funded by the National Science Foundation of Sri Lanka and grant from SIDA & SAREC.

References: 1. Iddamaldeniya, S. et al. (2006)J Carcinog. 5: 6–11.

2. Thabrew, I. et al. (2005) Life sciences 77: 1319–1330.

3. SIddamaldeniya, S. et al. (2003)J Carcinog. 2: 6–12.