A tuber lectin from Arisaema helleborifolium Schott with anti-insect activity against melon fruit fly, Bactrocera cucurbitae (Coquillett) and anti-cancer effect on human cancer cell lines

An anti-insect and anti-cancer lectin has been isolated from Arisaema helleborifolium Schott by affinity chromatography using asialofetuin-linked amino activated silica beads. The bound A. helleborifolium lectin (AHL) was eluted with 100 mM glycine-HCl buffer, pH 2.5. It gave a single band on SDS-PAGE, pH 8.3, and PAGE, pH 4.5. However, multiple bands were obtained in PAGE at pH 8.3 and isoelectric focusing. The lectin was a homotetramer having subunit molecular mass 13.4 kDa while its native molecular mass was 52 kDa. It was a glycoprotein with 3.40% carbohydrate and was stable up to 60 °C for 30 min. It showed anti-insect activity towards second instar larvae of Bactrocera cucurbitae (Coquillett) with LC50 value of 16.4 μg/ml. Larvae fed on artificial diet containing sub-lethal dose of AHL showed a significant decrease in acid phosphatase and alkaline phosphatase activity while esterase activity markedly increased as compared to larvae fed on diet without lectin. AHL was also found to inhibit in vitro proliferation of some well established human cancer cell lines viz HOP-62 (95%), HCT-15 (92%), HEP-2 (66%), HT-29 (68%), PC-3 (39.4%), and A-549 (20.7%).