Acute toxicity evaluation of a tepary bean (Phaseolus acutifolius) lectin

Abstract

As plant lectins have shown anticancer potential, we had previously tested the cytotoxic effect of a lectin from tepary bean on human cancer cells proliferation and the most sensible were colon cancer cells. Before testing the lectin against colon cancer in vivo, it is necessary to determine its toxicity, therefore the goal of the present work was to evaluate the acute toxicity of a concentrated tepary bean lectin fraction (TBLF). Female Sprague Dawley rats of 7 weeks old were administrated with the TBLF at doses of 5, 50, 300 and 2000 mg/kg body weight (423 OECD) by intragastric canula. Food intake was determined daily and body weight each 5 days, until 15 days. Highest doses caused diarrhea, lethargy and piloerection in the first 24 h, but a full recovery was observed after 48 h. After necropsy, no alterations were observed in liver, stomach, gut, colon, lungs, heart, thymus and spleen; no alteration was observed in the colon histology. Lectin adminstration increased leucocytes in 54% with 50 mg/kg (Tukey, p<0.05) and 2000 mg/kg decreased the number in 25%. TBLF by oral administration showed typical signs of lectins toxicity but it was not lethal and animals had a full recovery. Current studies are focusing on the evaluation of chronic toxicity.