TOXIC HEMAGGLUTININS IN VARIOUS EDIBLE BEANS AND PEAS

Abstract

A method involving ammonium sulphate fractionation and dialysis was used in the isolation of phytohemagg-lutininsfrom the young and mature seeds and pods of six edible legumes. The legumes used were soybean (Glycine max—kent variety) ; limaboan (Phaseolus lunatus - white seeded); groundnuts (Arachishypogea - Kano variety); pigeon pea (cajanus cajan - Ex-Ibadan); cowpea (Vigna unguiculata - Prima variety) and rice- boan (Vignaumbellata - Ivum variety). Considerable amounts of phytohemagglutinins were found in the young and mature seeds of all the legume species. However, the mature seeds contained significantly higher amounts of lectiens than the young seeds. Phytohemagglutinins wore absent from the young and mature pods of all the legume species. An immunological technique based on two-fold serial dilution was employed in estimating the relative and specific hemagglutinating activities of the 1ectins using trypsinised rabbit erythrocytes. Differences between the legumes in their specific hemagglutinating activities were observed. However, there was no significant difference between the specific hemagglutinating activities of lectins from the young and mature seeds. Qualitative tests revealed that all the lectins were glycoproteins and those from the mature seeds contained significantly higher amounts of protein and carbohydrate materials. Further investigations into their amino acid and carbohydrate make-up did not show any striking differences between the species.However, all the lectins from the young legume seeds showed deficiency in the amino acids tryptophane, tyrosine end phenylalanine. Ultra-violet and infra¬red spectroscopy revealed similar patterns for all the agglutinins from the young seeds and identical characteristics for all lectins from the mature seeds. Toxicological studies showed that these phytohe¬magglutinins were toxic to rats and chick embryos. Increases in the values of serum total and conjugated bilirubin, serum alkaline phosphatase levels, serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase(SGPT) levels were observed in agglutinin-poisoned rats,when compared with control animals. histopathological examinations also showed that the lectins effected considerable damage to some organs of poisoned rats and chick' embryos. Enzymatic studies with the liver of poisoned rats were carried out. Except in a few cases, significant inhibitions in the activities of ATPase and fumarase enzymes were observed. Activations in the activities of succinic, lactic, NAD+and NADP+ dependent isocitric dehydrogonases also oocurred in rats poiooned with lactins from young and mature seed. It is thus felt that these loctins affect carbohydrate metabolism in the rat liver at the anaerobic and aorobic phases. Investigations in the contents of calcium manganese and magnesium in the phytohomaggtinins did not reveal any significant differences between the lectins from the young and mature Seeds.while the manganes contents of the lectins from the mature seeds showed a negative correlation with their specific homagglutinating activities, and a positive correlation with their toxicities to rats, lectins from the young seeds only showed a negative correlation between their toxicities to rats and their magnesiun contents. The results of our study also discussed in terms of the differences between the legumes species with reference to their hemagglutinating and toxic properties