COMPOSITION, PHYSICO-CHEMICAL AND ANTIOXIDANT PROPERTIES OF OCIMUM GRATISSIMUM L. ESSENTIAL OIL FROM BURKINA FASO

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Résumé

Ocimum gratissimum L. is an aromatic herbaceous plant that is native to tropical countries especially West Africa, India and South America. It has been traditionally used for medicinal, condiment and culinary purposes and many biological properties have been reported on its essential oils (EOs). This study aims to determine the physico-chemical parameters and assess the antioxidant potential of this plant’s EO. Thus, fresh leaves of O. gratissimum were collected from the cultivated field of Irsat (Ouagadougou), Burkina Faso at the full blooming stage. These leaves were hydrodistilled and analyzed immediately after collection (fresh) to evaluate the quality of volatile constituents in terms of composition by GC-MS. Physico-chemical properties were determined by using international standards ISO. The antioxidant activity was determined by 2,2’-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging and the 2,2’ azinobis 3 ethylbenzothiazoline 6 sulfonic acid (ABTS) methods. The study revealed the presence of thymol (29.5%), γ-terpinene (20.5%) and p-cymene (12.9%) as EO major constituents. For physico-chemical parameters, the relative density value was less than 1. A low content of free acids was found. The EO had low light refraction and was found to be dextro-rotatory. The EO was soluble in 7 volumes of ethanol (70%) and values obtained for the acid index and refractive index were less than 2. The antioxidant activity showed DPPH radical inhibition value of 41.16 % at 0.1% of EO concentration with an IC50 value of 3.9 μg/ml. The ABTS radical inhibition value was 36.14 % at 0.1% of EO concentration with an IC50 value of 3.13 mg/ml. The present study has permitted to verification of the quality of O. gratissimum EO produced in Burkina Faso and showed that this oil could be a promising source of antioxidant compounds.

Mots-clés

Ocimum gratissimum, Essential oil, Chemical composition, Antioxidant, Traditional medicine, Composition (language), Chemistry, Food science, Medicine, Biochemistry, Organic chemistry, Art