Chemical and Microbiological Investigations of Cassia fistula Linn

Abstract

Three lectins were extracted and purified from Cassia fistula seeds in biologically active form by gel filtration of I 00 % ammonium sulfate saturated crude protein extract on Sephadex G-50 followed by ion-exchange chromatography on DEAE celluiose and then affinity chromatography on Sepharose 4B. The lectins were found to be homogeneous justified by polyacrylamide disc gel electrophoresis. The molecular weights of the lectins CSL-I, CSL-2 and CSL-3, determined by gel filtration on Sephadex G-75 column were 37,000, 42,400 and 46,000, and by SDS gel electrophoresis were 37500, 42000 and 46500, respectively. The lectins agglutinated rat red blood cells and the agglutination was inhibited specifically by galactose and galactose containing saccharide. The neutral sugar contents of the lectins, CSL:-1 , CSL-2 and CSL-3 were estimated to be 3.5, 3.1 and 2.0 % respectively. The sugar composition of the lectins was found to be galactose for CSL-I, galactose and glucose for CSL-2, and galactose and mannose for CSL-3. The lectins displayed strong cytotoxic effect in brine shrimp lethality bioassay and among the lectins purified, CSL-2 was found to be highly toxic followed by CSLI and then CSL-3. The purified lectins in aqueous solution gave absorption maxima around 274-278 run and minima around 243-248 run. Biological activities of the lectins CSL-I, CSL-2 and CSL-3, were investigated after various physico-chemical treatments. Biological activities were highly affected with the changes of pH and temperature, and the lectins exhibited maximum hemagglutinating activities around pH 7.2 to 7.5 and at temperature 20° to 35 °C. Biological activities of the lectins were abolished sequentially with the increase in concentration of acetic acid and denaturant solutions such as urea and guanidine-HCI.-----