Anthraquinone content and toxicity test of Cassia fistula pod extracts

Cassia fistula Linn. (Caesalpiniaceae) can be easily found in all parts of Thailand as an ornamental plant and its ripe pods are almost treated as a waste. In Thai traditional medicine, the ripe pods of C. fistula have long been used as a laxative drug. They contain several anthraquinones such as rhein, aloe-emodin and sennosides [1], These anthraquinones promote laxative effect of which their glycosides contents indicate the laxative potency [2]. In this study, the ripe pods of C. fistula were collected from 10 different provinces of Thailand. The pod pulp was separated and extracted with distilled water by decoction. The water extracts were determined for the contents of total anthraquinones and total anthraquinone glycosides by a UV-vis spectrophotometric method at 515nm and the acute toxicity of the extracts was investigated in mice and rats. Extract ratio (crude drug: 1g crude extract) of all the extracts are 1–2: 1. The contents of total anthraquinones and total anthraquinone glycosides in the extracts calculated as a major anthraquinone rhein were 1.45–1.85% w/w (average 1.63% w/w) and 0.38–0.71% w/w (average 0.53% w/w), respectively while in the fresh pod pulp contained 0.89–1.03% w/w (average 0.94% w/w) and 0.22–0.39% w/w (average 0.31% w/w), respectively. After tested mice and rats were administered with the extract at dose level 5g/kg, no mortality or any sign of toxicity were found within 14 days. The body weight gain of all animals was not significantly different between the treated groups and the respective control group. This indicats that C. fistula pod extract was grouped in a slightly toxic (LD50 >5g/kg). In Thai traditional medicine, the fresh pod pulp 4–8g has been used as a dose for laxative drug. This dose amount was equal to 37.6–75.2mg of total anthraquinones and 12.4–24.8mg of total anthraquinone glycosides. From our preliminary study, it suggests that the decoction extract of C. fistula pod might be used as an alternative source of natural laxative drugs and should be further developed as a modern pharmaceutical laxative preparation.

References: 1. Indian Council of Medical Reseach (2005) Quality standards of Indian medicinal plants Vol.2, Indraprastha Press (CBT), New Delhi: 47–53.

2. Bruniton J (1995) Pharmacognosy, Phytochemistry, Medicinal plants, Lavoisier Publishing, Paris: 349–354.