Biological and chemical characterization of haemagglutinins from three edible varieties of Lima beans (Phaseolus lunatus, Linn.)

Lectin from seeds of a Brazilian lima bean variety (Phaseolus lunatus L. var. cascavel) presents antioxidant, antitumour and gastroprotective activities

Lectins are proteins able to interact specifically and reversibly with carbohydrates. They are present in all living beings, particularly in legume seeds, which have many biological functions. The aim of this study was to isolate, characterize and verify antioxidant, anti-hemolytic, antitumor and gastroprotective activities in a lectin present in seeds of Phaseolus lunatus L. var. cascavel (PLUN). The isolation of lectin was performed by size exclusion chromatography on Sephadex G-100, which was isolated from a protein capable of agglutinating only human erythrocytes type A, being this the only inhibited haemagglutination n-acetyl-d-galactosamine. Its weight was estimated by PAGE is 128kDa. The lectin is thermostable up to 80°C and is active between pH 2-11. As 8M urea was able to denature the lectin. PLUN is a glycoprotein consisting of 2% carbohydrate and has antioxidant action with ascorbic acid equivalent antioxidant capacity (μMAA/g) of 418.20, 326 and 82.9 for total antioxidant activity, ABTS radical capture and capture of DPPH radical, respectively. The lectin has antitumor activity against melanoma derived cells at doses of 100 and 50mg/ml, reducing up to 83% tumor cells, and gastroprotective action, reducing up to 63% damaged area of ​​the stomach induced by ethanol.

Compositional evaluation of some cowpea varieties and some under-utilized edible legumes in Nigeria

The nutritive potentials of some cowpea varieties such as Ife Brown, Ife Bimpe, IT84E-124, K59 and TVX716 and some under-utilized edible legumes grown in Nigeria such as pigeon pea (Cajanus cajan), lima bean (Phaseolus lunatus), lablab bean (Dolichos lablab), mucuna bean (Mucuna sp.) and Sphenostilis sternocarpa have been evaluated with respect to their proximate chemical composition, mineral content and some endogenous toxic constituents. The cowpea varieties contained on the average 22.5 g crude protein (CP), 2.60 g crude fibre (CF), 5.89 g either extract (EE) and 3.36 g ash/100 g DM while the under-utilized legumes contained 21.7, 6.10, 2.86, and 3.56 g/100 g DM for CP, CF, EE and ash respectively. Distinct varietal differences were observed for EE values as indicated by the coefficients of variation (CV) of 102% for cowpea and 60.8% for the under-utilized legumes. The CF content of the under-utilized legumes were generally higher than those of the cowpea varieties. Potassium was the most abundant mineral in both the cowpea varieties and the under-utilized legumes with mean values of 1.45 and 1.66% respectively, while P was the least abundant with 13.1 and 8.50 ppm, respectively. There were marked intra-varietal differences in the P content as shown by the high CV of 84.0 and 73.9% for the cowpea varieties and the other legumes. The cowpea varieties generally had higher levels of thioglucosides, trypsin inhibitor activity (TIA) and lower haemagglutinating activity (mean values of thioglucosides: 3.86%, of TIA: 13.9 mg/g protein and of haemagglutinating activity: 13.0 HU/mg N respectively), than the under-utilized legumes with mean respective values of 1.22%, 9.84 mg/g protein and 22.7 HU/mg N. The nutritional implications of these anti-nutritional components were discussed and some reasons adduced for the under-utilization of some of these legumes inspite of their apparent similarity in nutritional quality to the more commonly consumed grain legumes.