Comparative study of the antioxidant properties of essential oils of thymus vulgaris and ocimum gratissimum, two plants of the lamiaceae family

The present work aim is to evaluate the antioxidant properties of the essential oils extracted from Thymus vulgaris and Ocimum gratissimum in order to promote their use in the food, cosmetic and pharmaceutical industries. It is about to establish a link between the chemical composition of these oils and their antioxidant properties. The composition of the essential oils was determined by gas chromatography. The antioxidant powers are evaluated using the reducing power of the ferrous ion and the trapping power of the radical DPPH°. The results show that both essential oils have similar chemical profiles. In fact, apart from -pinene (8.80%) and -selinene (5.50%) which are absent in the major compounds of the essential oil of Thymus vulgaris, and carvacrol (2.79%) absent in those of the essential oil of Ocimum gratissimum, all the other major constituents are present in the two essential oils with relatively variable contents. The IC50 values, obtained using the DPPH method, prove that the oil of Thymus vulgaris is more antioxidant with 481.70 ppm than that of Ocimum gratissimum with 822.37 ppm. In addition, the results of the FRAP test show that the free radical activity (in Eq of Fe2+) of the oil of Thymus vulgaris, ie 603.50 ppm, is greater than that of the oil of Ocimum gratissimum, ie 513.50 ppm. The antioxidant activities presented by these oils could be attributed to the presence of their phenolic compounds. Used as food additives, these essential oils can thus contribute to reduce the risk of occurrence of certain diseases related to oxidative stress.