Phytochemical Study and Comparative Evaluation of Activity of Mitracarpus scaber Zucc. and Ocimum gratissimum Lin. Extracts on the in vitro Growth of Fusarium oxysporum sp. Radicis-lycopersici

Mitracarpus scaber Zucc. (Rubiaceae) and Ocimum gratissimum Lin. (Lamiaceae) are two species of Ivorian medicinal plants known for their antifungal and insecticidal activity. The aim of the present work is to evaluate the activity of various organic extracts of these plant species on the in vitro growth of Fusarium oxysporum sp. radicis-lycopersici, an agricultural contaminant toxin, and to make a phytochemical screening of plant extracts. Hydroalcoholic extract (ethanol 70 %) solution was used. Then from alcoholic extracts, other samples were obtained by using mixtures of solvents petroleum ether/water (v/v) and dichloromethane/water (v/v). All these extracts were tested on the in vitro growth of Fusarium strain according to method of agar double dilution inclined tubes with concentrations ranging from 6250 µg /mL to 97.5 µg /mL. Results of this evaluation showed that F. oxysporum sp. was sensitive to all plant extracts in a dose-response relationship. Concerning the extracts of M. scaber (MS) and O. gratissimum (OG) , the best performance was obtained for the etheric extracts MS11 and OG11 from a mixture of petroleum ether/water (v/v) with MIC = 390 µg/mL and 781 µg/mL. The lowest antifungal parameters were obtained from the aqueous phases of the solvents mixtures. The MIC values ​​range from 3125 µg/mL to 6250 µg/mL. However, for all tested extracts, activities of M. scaber extracts have been better than those of O. gratissimum. Also, the activity of the basic hydroalcoholic extract was improved up to 4 times, function of extraction method used. Moreover, phytochemical screening performed for each sample revealed a very strong color intensity to the sterols and triterpens in the most active extracts OG11 and MS11. The activity of the extracts of these plant species on the in vitro growth of F. oxysporum sp. Radicis-lycopersici was the result of sterols and triterpens presence.