Abstract

SO Salawu* AA. Akindahunsi , EO. Ibukun and KG Duodu

There is a growing interest in preventive health care for the development and evaluation of natural antioxidants from plant food. Therefore, this study sought to investigate the phenolic composition of Solanum macrocarpon and Hibiscus esculentus leaves using HPLC/DAD/MS techniques, evaluate the radical scavenging activities, ferric reducing properties and assess the inhibitory action of the vegetable extracts against Low Density Lipoprotein (LDL) and egg yolk lipid- rich oxidation. The HPLC analysis revealed the presence of cynamoyl derivative, two chlorogenic acid derivatatives, rutin and Kaempferol-3- rutinoside in S. macrocarpon and five dicaffeoyl derivatives, unidentified flavonoid and isoquercitrin in Hibiscus esculentus leaf. The result indicated that the total phenolic content (mg tannic acid equivalent/g) and 2, 2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging (µmol trolox equivalent/g) activities were higher in Hibiscus esculentus phenolic extract (12.96± 0.04; 2.44E-05 ± 4.52E-06), respectively. Similarly, ferric reducing antioxidant power (mg ascorbic acid/g ) and 1, 1-diphenyly-2- picrylhydrazyl radical scavenging (µmol trolox equivalent/g ) activities were slightly higher in Hibiscus esculentus extract (10.60 ± 0.14; 2.68E-05 ± 1.56E-05), respectively. The result also showed that the studied vegetable extracts inhibited both human LDL and lipid rich egg homogenate oxidation. Overall, the antioxidant action and protection against lipid oxidation could be linked with the presence of the phenolic compounds in the vegetable extracts and the consumption will be of immense benefit in the prevention of a number of free radical mediated diseases.