Phytochemical analysis and antioxidant potential of Ocimum gratissimum Linn (Lamiaceae) commonly consumed in the Republic of Benin

ABSTRACT

In the Benin pharmacopoeia, the use of Ocimum gratissimum Linn (Lamiaceae) based on the empiricalknowledge is widespread. The objective of this work is the matching of the virtues attributed to this plant in folkmedicine with the biomolecules present through a thorough phytochemical exploration. Standard screeningis based on the differential reactions of precipitation and staining. Phenolic compounds, total flavonoids,and condensed tannins were quantified by colorimetric Folin–Ciocalteu, AlCl3, and acid vanillin methods,respectively. Phenolic acids were investigated by the HPLC Ultimate 3000 chain and the antioxidant capacityevaluated by the ferric reducing antioxidant power method coupled with that of 2,2-diphenyl-1-picrylhydrazyl.Standard screening revealed the presence of flavonoids, alkaloids, tannins, anthracene derivatives, steroids, andterpenoids. The total contents of phenolics, flavonoids, and tannins were 56.59 mg gallic acid equivalent /100mg, 13.71 mgEQ/100 mg, and 8.6 mgEC/100 mg, respectively. For specific assays, three flavonoids (chrysin,isorhamnetin, and quercetin) and six phenolic acids (tannic, ellargic, ferrulic, syringic, chlorogenic, and caffeic)have been identified. The antioxidant activity ranges from 78.92 to 106.25 mmol. Ascorbic acid equivalent /gextract with free radical inhibition ranging from 5.24% to 76.59%. The 50% inhibitory concentration givinga value of 6.175 mg ml−1 is greater than that of the pure molecule. The presence of these phytocompoundsendowed with antiradical power testifies to the medicinal potentialities of O. gratissimum. These resultsconfirm the empirical use of O. gratissimum in this study area