In Vitro Discovery of Watermelon (Citrullus Lanatus) Extract with Moderate Chelating Ability, and Survey of other in Vitro Bioactivities
Olabinri BM, Olaleye MT, Ajani RA, Akinmayowa.S, Busayo OO, Funmilola.A

Abstract
Ferrous chelating ability of aqueous mesocarp extract of watermelon(Citrullus lanatus ) was discovered at the lowest concentration(1%).The aqueous extract of the plant part(mesocarp, the edible portion) displayed moderate chelating ability(55.45,% at 15min) in vitro for ferrous ion(Fe2+).The extract failed to bind Fe2+ at other concentrations(2- 5%).The extract also failed to chelate ferric ion(Fe3+) in vitro at 1% concentration.This discovery was fortunate in that the aqueous extract of the plant at that concentration (1%) could be strategically targeted for the reduction of iron( ii ) ion in all situations of iron-overload disorders because of its moderate chelating potential.The in vitro inhibition of lipid peroxidation by aqueous extract of watermelon plant parts was in the order:epicarp > endocarp > mesocarp.The aqueous extract of the three parts of the plant showed weak inhibition of lipid peroxidation in vitro(2.58±0.19 to 27.50±1.03 % ) within the concentration range investigated(2 -10%).The aqueous extract of C.lanatus failed to scavenge nitric oxide radical in vitro, but 70 % methanolic extract demonstrated potent in vitro nitric oxide radical scavenging potential at all concentrations investigated(2- 10%).The in vitro antioxidant activity of the aqueous mesocarp was in the region of 60% activity for all the concentrations(2- 10%), and their differences were not significant (P >0.05).The in vitro hydroxyl radical scavenging activity of the endocarp(70% methanol),mesocarp(water extract) and epicarp(70% methanol) of the plant were remarkable ,mostly in the vicinity of 80% activity for most of the concentrations.The in vitro nitric oxide scvaenging potentials of the 70% methanolic extract were 71.3% at 2% concentration and 70.4% at 4% concentration for endocarp and epicarp extracts ,respectively. The 70% methanolic extract of the plant could be exploited for the treatment of inflammatory diseases because of its potent in vitro nitric oxide scavenging capability.

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