Identification of a new lectin from citrullus lanatus (watermelon) and Solanum muricatum (pepino melon)

Lectins have been used in previous research for new treatments for diseases such as cancer due to their carbohydrate binding specificity. Lectins are mainly found in vegetative species, such as seeds, bulbs, flesh, and stems. In this research project, Citrullus lanatus (watermelon) and Solanum muricatum (pepino melon) were the main fruits that were studied for lectin activity. These fruits were chosen because they are both part of families that have reported lectins. Lectin activity was observed through agglutination in watermelon and pepino melon with 2% sheep red blood cells. To our knowledge, we are the first to report lectin activity from these plant species. The molecular weight of our lectins were determined by centrifuge filtration and gel electrophoresis. The binding specificity of our lectins were determined by incubating our crude extract with various monosaccharides, glycoproteins and polysaccharides. It was found that watermelon bound to the polysaccharide chitin and pepino melon bound to the glycoprotein invertase and chitin. The subunit molecular weight of watermelon lectin was determined to be around 10 kDa. In contrast, the subunit molecular weight of pepino melon lectin was found to be between 20-37 kDa. In future research, we will determine the purification process for isolating these new lectins and their biological application.