Isolation of Jatropha Curcas Seeds Isolectins with Variable Affinity for Human and Animal Blood Types

Background: Lectins are carbohydrate-binding protein which agglutinate glycoconjugates in a reversible way, they are with wide applications in biological and medical sciences. Jatropha curcas belongs to the family euphorbiaceae and is distributed in many tropical and subtropical countries. The toxicity of this plant is known for long ago and has been attributed to several components among which is a protein called curcin.
Methods: Jatropha curcas seeds were pulverized and protein was extracted with suitable buffer. Protein extract thus obtained had undergone successive protein precipitations by salting-out using (NH4)2SO4 (AS) at 40, 60, and 80% saturations. Lectin activity was detected by hemagglutination method using human- and animal blood types. AS-precipitated protein fractions that possess lectin activity were tested for their antimicrobial activity against the pathogenic Staphylococcus aureus, Escherichia coli, Bacillus aueras, and Candida albicans.
Results: At least three isolectins (Lec40, Lec60, and Lec80) were detected by hemagglutination (HA) and isolated by AS fractionation from the crude Jatropha curcas seed extract (CExt). The isolectins exhibited different tendency toward human and animal blood types. None of the isolectins could inhibit any of the used bacterial strains and Candida albicans.
Conclusions: In this study, though the detected lectins resemble their counterpart legume lectins, they, however, showed apparently unique and variable behavior toward human and animal blood types. Which might emphasize on the need for further structural analysis on the affinity sites of these proteins.
Keywords: Jatropha curcas; euphorbiaceae; lectin; hemagglutination; antimicrobial activity