Phytochemical study and evaluation of the antiviral activity of aqueous extracts of three medicinal plants; Xylopia aethiopica, Gliricidia sepium and Ocimum gratissimum used in Cote d'Ivoire

Abstract

Background: The present work is part of the exploration of new antiviral molecules to combat antimicrobial resistance. In purpose, this study determined the phytochemical analysis, cytotoxicity and antiviral activity of extracts from three Ivorian medicinal plants; Gliricidia sepium, Ocimum gratissimum and Xylopia aethiopica against poliovirus 1, a non-enveloped RNA virus.

Methodology: Aqueous extract of the three plants, which were identified at the herbarium of National Floristic Center Abidjan, was done using a previously described method. The precipitation or staining technique was used to highlight the chemical groups in the three extracts while the polyphenol content of each extract was assessed by the colorimetric method. Cytotoxicity and antiviral activity tests were performed in 96-well plates. Cytotoxicity of each extract on L20B (a genetically engineered mouse cell line) was determined by observation of the cell line carpet. Antiviral activity of three extracts against poliovirus type I was determined after 72 hours using an assay that measures inhibition of the cytopathic effect on cell culture.

Results: The three plant extracts contain polyterpenes, sterols and polyphenols, flavonoids, catechetical tannins, saponosides and quinones but none of the extract contains gallic tannins. With the exception of O. gratissimum, alkaloids were found in extracts from the two other plants, and extract of G. sepium was richer in polyphenol than the other two extracts. The cell carpet of L20B after 72 hours contact period with three extracts remained intact at concentrations ranging from 2 to 1000 μg/ml. The aqueous extract of G. sepium showed higher antiviral activity on poliovirus 1 (74.569%) at 2µg/ml than the extracts of O. gratissimum (45.6112%) and X. aethiopica (44.5247%) after 72 hours of incubation.

Conclusion: The extract of G. sepium showed potent antiviral activity against poliovirus 1 than that of O. gratissimum and X. aethiopica. This was justified by its higher polyphenol content than the two extracts.