Moringa oleifera seed lectin inhibits Ehrlich ascites carcinoma cell growth by inducing apoptosis through the regulation of Bak and NF-κB gene expression

A Moringa oleifera seed lectin (MOSL) was purified by using chitin column with the molecular mass of 17 ± 1 kDa. The lectin agglutinated mouse, cow and human erythrocytes and the hemagglutination activity was inhibited by methyl-α-d-mannopyranoside, methyl-β-d-galactopyranoside, lactose and glucose. The lectin exhibited 100% hemagglutination activity at the pH range from 8.0 to 9.0 and temperature range from 30 to 60 °C. Additionally, the lectin gradually lost its activity in the presence of urea but the activity abolish completely when treated with EDTA. MOSL showed mild toxicity against brine shrimp nauplii with a LC50 value of 131.0 μg/ml. Antiproliferative activity was studied against Ehrlich ascites carcinoma (EAC) cells and 71.08% cell growth inhibition was observed in vitro at 200 μg/ml. The lectin was injected (i.p.) into EAC mice at the doses of 2.0 and 4.0 mg/kg/day for five consecutive days and 25.38% and 55% of cell growth inhibition was observed, respectively. MOSL caused the cell cycle arrest at G2/M phase as determined by FACS flow cytometry. The cell growth inhibition was due to the induction of apoptosis in the EAC cells which was confirmed by cell morphological study, caspase-3 inhibitor and activation of Bak and suppression of Bcl-2 and NF-κB genes expression.