Abstract

Barakol is a biologically active constituent extracted from leaves and flowers of Cassia siamea Lamk. Barakol has been used as Thai traditional medicine to treat anxiety and insomnia in human patients. The postulated mechanism of barakol is that it may act as a dopamine agonist to inhibit endogenous dopamine release via dopamine D₂-receptor.¹ In addition, the D₂-receptor also regulates dopamine release in fish and plays an important role in sedation. However, both acute and subacute hepatotoxicity induced by barakol has been reported. In a search for suitable cell culture models to assess barakol toxicity, we have focused on hepatocytes from carp fish (Cyprinus carpio). Hepatocytes have important detoxication function and are also primary target of barakol toxicity. The aim of the present study was to determine the in vitro cytotoxic effects of barakol in hepatocytes of carp. A preparation of barakol extracted according to Bycroft et al,² was characterized and identified by using a high-performance liquid chromatography (HPLC).³ Isolated hepatocytes were cultured in Leibowitz-15 media supplemented with 30% fetal bovine serum (FBS) and antibiotics. The cultures of hepatocytes were treated with barakol at the concentrations of 0.07-5 mM and then incubated for 24, 48, and 72 hours. Decreased mitochondrial metabolism was used as the endpoint for cytotoxicity determined by the XTT reduction assay. The results showed a reduction of cell viability to 73.9, 72.3, and 69.0% within 24, 48, and 72 hours at 5 mM of barakol concentration, respectively. It indicated that the reduction of mitochondrial function depends on barakol concentration whereas period of the incubation time had no significant effect. Barakol at concentrations lower than 1.25 mM did not affect on cell viability significantly. Interestingly, this is the first report on the cytotoxicity effect of barakol on cultured hepatocytes from carp. Furthermore, this in vitro cytotoxicity study may be used as a model for investigation of other toxic compounds on hepatocytes from fish.

Acknowledgements

This work was financially supported by a grant from Mahidol University, Nakornpathom., Thailand.

References

1.  Bulyalert D. 1992. Effect of barakol on the central nervous system: quantitative analysis of EEG in the rat. Chiang Mai Med. Bull.32: 191-196.

2.  Bycroft BW, Hassaniali WA, Johnson AW, King TJ. 1970. Structure and synthesis of barakol; a novel dioxyphenalene derivative from Cassia siamea. J. Chem. Soc. 12: 1686-1689.

3.  Thongsaard W, Shainakul S, Bennett GW, Marsden CA. 2001. Determination of barakol extracted from Cassia siamea by HPLC with electrochemical detection. J.Pharm. and Biomed.Anal. 25: 853-859.