Synergism and Antagonism of Essential Oil Fractions of Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris Against Penicillium expansum

Abstract

The prevailing spread of food-poisoning orchestrated by mycotoxin producing Penicillium expansum strains and others on post-harvested crops and food is a preoccupying issue in tropical countries especially Cameroon. The search for antifungal bio-preservatives to curb this health-threatening issue has become adamant. A study was carried out to evaluate the antifungal potential, constituents of Cymbopogon citratus (CC), Ocimum gratissimum (OG) and Thymus vulgaris (TV) Essential oil (EO) fractions, synergism and antagonism between active and non-active fractions against P. expansum predominant strains in Cameroon. The antifungal potency was determined by supplemented broth dilution technique which revealed EO fractions from OG was significantly active against P. expansum strains than those from CC and TV in that sequence at 1000 ppm. Gaseous phase chromatography coupled with mass spectrometry (GC/MS) illustrated fractions rich with oxygenated terpenes exhibited high antifungal potentials than their whole EO counterparts. Conversely, rich hydrocarbon terpenes fractions displayed a far lesser antifungal potency than their whole EO. Inter-blending active subfractions (CC1C/OG1C and CC1C/TV1B) for the three EO at 1000 ppm depicted a stronger antagonistic effect; whereas non active subfractions (CC1A/OG1A and CC1A/TV1A) inter-blends exhibited strong synergistic effects against the two strains of P. expansum. This pathfinder work urges the exploitation of this synergistic effects of active fractions as a probable optimized bio-preservative agent against P. expansum; but recommending the non usage of active fractions blend exhibiting antagonistic effect's for the control of the latter.