Spectral and chemometric analyses reveal antioxidant properties of essential oils from four Cameroonian Ocimum

Abstract

Antioxidants used to protect unstable unsaturated fatty acids from oxidation are toxic or lose their potential in fats. The aim of this work was to investigate the protective effect of Ocimum essential oils against auto-oxidation of flaxseed oil. Essential oils were extracted from leaves of cultivated Ocimum basilicum, Ocimum canum, Ocimum gratissimum and wild type Ocimum urticaefolium. Chemical profiles of the essential oils were determined using Fourier Transformed Infrared-Attenuated Total Reflectance (FTIR-ATR) coupled with chemometric analyses. The antioxidant effect was measured on flaxseed oil under accelerated oxidation for 15 days. The structural change of the flaxseed oil was investigated by spectrophotometric and titrimetric methods. Linalool/Eugenol, Eucalyptol, Thymol/γ-Terpinene, and Eugenol/ β-Bisabolene were found to be the respective chemotypes of Ocimum basilicum, O. canum, O. gratissimum and O. urticaefolium. The essential oil from O. urticaefolium showed the highest protective effect at 5μl/ml, and was comparable to that of Butylated Hydroxy-toluene (BHT) (100μg/ml) (p≤0.05). The results achieved are promising and supported further studies of the tested essential oils for application to prevent oil oxidation during storage.