ISOLATION, IDENTIFICATION AND TOXICITY OF SAPONIN FROM DIFFERENT LEGUMES

Saponin extracts were prepared from peas, beans and soya bean seeds by four different methods. Two biological assays were developed for meas uring toxicity of crude saponin extracts based on haemolytic activity and fish mortality. The results indicated that saponin extracts were a ble to lyse red blood cells with different velocity. The haemolytic ac tivity of bean extracts were significantly higher (P < 0.05) than thos e of soya bean and pea extracts. Sensitivity of blood cells to crude s aponin extracts was detected by sheep and rabbit blood cells. The high est haemolytic activities of sheep and rabbit blood cells were 30.0 an d 6.24 mg saponin equivalent/g legume sample, respectively. As well as being potent haemolysins, saponin extracts were lethal to guppy fish. The lethal dose (LD(50)) of saponin to guppy fish was 150 mu g/ml. Th e ethanol/water (1:1) extracts showed the highest toxicity as revealed by both assays. Thin-layer chromatography (TLC) of crude saponin extr act from beans separated it into six fractions, whereas pea and soya b ean were separated into seven and six fractions, respectively. The TLC pattern of standard saponin indicated the presence of two main spots with R(f) 0.75-0.85. Further purification of crude saponin extracts fr om legumes by silica gel column chromatography increased the haemolyti c activity of the active principle 5.7, 5.1 and two-fold for bean, soy a bean and pea extracts, respectively.