ABSTRACT
Senna siamea (Lam.) Irwin and Barneby is a medicinal plant popularly used in Thailand. Young leaves and/or young flowers of this plant have been consumed by Thai people as a Khi Lek curry for a long time. The fresh young leaves and flowers are boiled with water 2-3 times to get rid of the bitterness and the boiled mush is used for curry cooking. Barakol, a major constituent of Senna siamea leaves was analyzed for its content in the fresh young leaves, the boiled leaves and the boiled filtrates by a high-performance thin-layer chromatographic method. Fresh young leaves of S. siamea contained 0.4035% w/w barakol. The amount of barakol in the first and second boiled filtrates were 0.2052 and 0.1079% fresh weight, while the first and second boiled leaves samples were 0.1408 and 0.0414% fresh weight, respectively. The results show the process of preparation of Khi Lek curry by boiling S. siamea young leaves twice with water reduced barakol content up to 90% and the content of barakol in boiled leaves used for curry has much less tendency to cause liver toxicity. This may explain the reason why Thai Khi Lek curry has not caused hepatotoxicity, unlike S. siamea leaves consumed as a powdered capsule.