Effect of boiling on the phytochemical constituents and antioxidant properties of African pear Dacryodes edulis seeds in vitro

Abstract

African pear, Dacryodes edulis, seed extract has been used for the treatment of ailments in traditional medicine. However, the effect of boiling on its antioxidant properties is still poorly understood. Therefore, the present study investigates the effect of boiling on the antioxidant properties of D. edulis seed extract using in vitro parameters such as free radical scavenging ability against 2, 2- diphenyl -1- picrylhydrazyl (DPPH) radical, iron (III) reducing and iron (II) chelating ability. Furthermore, the ability of both extracts (boiled and unboiled) to offer protective benefit against lipid peroxidation in cerebral and hepatic tissues of rat was assessed. Moreover, the effect of boiling on the phytochemical constituents (total phenolics, flavonoids and vitamin C) of the seed extracts was measured. Results indicate that boiling significantly (P < 0.05) potentiates the total phenolic [(Boiled 60.1 ± 0.88 mg/g (GAE); Unboiled 30.2 ± 0.68 mg/g (GAE)] and flavonoid [(Boiled: 50.02 ± 0.12 mg/g (QE); Unboiled: 35.8 ± 0.15 mg/g (QE)] content but mildly depleted the vitamin C content [Boiled: (36.9 ± 0.44 mg/g; Unboiled: 40.1 ± 0.21 mg/g]. Similarly, boiling markedly increased the antioxidant properties (free radical scavenging, iron (II) chelating, iron (III) reducing and inhibitory effect against pro-oxidant-induced lipid peroxidation) of the seed extract. From the foregoing, the wide usage of African pear as remedy for ailment in folk medicine may be due to its phytochemical constituents which are potentiated by boiling. Hence, information from this study would create public awareness especially to traditional medical practitioners who are involved in the act of boiling the fruit to get the extract used for medicinal purposes. Key words: African pear, phytochemical, degradation, proxidant, antioxidant, mechanism, lipid peroxidation.