Hemical Composition And In Vitro Antioxidant Activities Of The Essential Oils Of Hibiscus Sabdariffa Seeds:- Elekwa, Francis O

ABSTRACT Antioxidants play major roles in counteracting the deleterious effects of oxidative stress in biological systems; and the antioxidant potentials of plants and plant parts are related to the phytoconstituents inherent in them. This study was therefore aimed at evaluating chemical composition and antioxidant activities ofthe essential oil ofHibiscus sabdariffa seeds (EOHSS) using 2,2-diphenyl-l-picrylhydrazyl (DPPH) spectrophotometric assay. The essential oil of Hibiscus sabdariffa seeds (HSS) were subjected to phytochemical analysis using gas chromatography coupled to flame ion detector (FID) and mass spectrometer (MS). The total phenols, total flavonoids and total antioxidant capacity were determined using standard methods. The antioxidant property was examined using the DPPH scavenging radical assay at the concentrations of 100 - 400 mg/ml and butylated hydroxytoluene (BHT) as reference standard. The experiments were conducted in triplicate. Data was subjected analysis of variance (ANOVA) using SPSS, while values were presented as mean ± standard deviation. Significance was set at p<0.05. According to the results, EOHSS contain bioactive compounds including Dlimonene (23.45 ug/ml), ferullic acid (26.27 ug/ml), vanillic acid (15.00 ug/ml), tyrosol (14.66 ppm), naringenin (19.24 ug/ml), epicathechin (9.25 ug/ml), ellagic acid (7.28 ug/ml) and beta pinene (8.04 ug/ml). Appreciable levels of phenols and flavonoids were also detected. The DPPH assay result showed that the highest scavenging activity Of the EOHSS was detected at 200 mg/ml (94.08%) compared to the standard (98.44%). A dose-dependent decrease in percentage inhibition was observed as the concentration increased from 200 - 400 mg/ml of EOHSS. The relatively high phenol and flavonoid contents of EOHSS in this study strongly contribute to its antioxidant activity. Hence, it could be exploited for therapeutic purposes against oxidative stress-related diseases