Effect of processing on hemagglutinin activity of lectin extract from selected green vegetables (Vernonia amygdalina, Gnetum africanum, Petrocarpus soyauxil and Telifera occidentalis)

Abstract

Lectins are carbohydrate binding proteins present in most plants and plant foods. They are toxic,
inflammatory, and resistant to cooking and digestive enzymes. In this study, lectins were extracted from
Okazi leaf (Gnetum africanum), Bitter leaf (Vernonia amygdalina), Fluted pumpkin leaf (Telferia occidentalis),
and Oha leaf (Pterocarpus soyauxii). Partial purification of the lectin extracts was achieved by precipitation
with ammonium sulphate and the extracts were tested for hemagglutinin activity using 4% suspension of
human erythrocytes in lectin buffer. The blood specifity of the different blood groups was observed in the
variation of lectins activities in a0, a1 and a2. The hemagglutinin activities of the vegetable lectins decreased
slightly at 60°C when exposed to processing (moist heating and oven drying) but at 100°C there was no
agglutination activate in Onugbu and Okazi vegetables except in a1 for blood group A and B in fluted
pumpkin and Okazi leaves respectively. Loss in agglutinations activity suggest that lectins from these
vegetables are heat labile and can be deactivated by moist or dry heating.