Assessment of the Phytochemical Constituents and Antioxidant Properties of Oils from Dura and Tenera Varieties of Elaeis guineensis Fruits

Abstract

There have been acclaimed medicinal benefits of palm oil and palm kernel oil by rural dwellers in the southeastern part of Nigeria. The study investigated the phytochemical constituents and antioxidant properties of the different varieties of the oil using standard methods. The oil samples include: DPO (dura palm oil), TPO (tenera palm oil), NDPKO (dura native palm kernel oil), NTPKO (native tenera palm kernel oil), HDPKO (dura palm kernel oil of hexane extract) and HTPKO (tenera palm kernel oil of hexane extract). Results obtained revealed the presence of steroids, glycosides, terpenoids, triterpenes and phenolics in all the oil samples whereas saponins, flavonoids and coumarins were only detected in DPO, TPO and NDPKO. The result of the quantitative phytochemical analysis of the oil samples showed that NDPKO statistically had the highest contents of terpenoids (1.77 ± 0.14 mg/kg) and triterpenes (288.50 ± 23.30 mg/100g). Saponins, flavonoids and coumarins were highest in DPO with values corresponding to 1.00 ± 0.001 mg/kg, 308.30 ± 1.81 mg/100g and 43.98 ± 0.13 µg/100g respectively. Furthermore, NTPKO was found to have the highest content of steroids (150.40 ± 0.24 mg/100g) while TPO had the highest content of glycosides (9.01 ± 0.07 mg/100g) and phenolics (45.04 ± 0.12 mg/100g) at p<0.05. TPO had the highest content of β-carotene (2.06 ± 0.00 mg/100ml) and vitamin A (105.60 ± 0.15 IU/100ml) but had the lowest vitamin E content (3.73± 0.30 µg/ml) whereas HTPKO had the highest (p<0.05) content of vitamin E (4.67 ± 0.03 µg/ml) among the oil samples. NTPKO had the highest FRAP (780.00 ± 1.82 µg/100g) while DPO had the least (p<0.05) FRAP (601.30 ± 0.91 µg/100g). The oil samples exhibited a concentration-dependent increase (p<0.05) in percentage inhibition of DPPH free radical showing an antioxidant capacity of about 70-80%. The results obtained from the physicochemical and antioxidant properties of the oil samples showed significant positive effects thus justifying their ethnomedical use.