Assessment of Quality and In Vitro Activities of Essential Oils Extracted from Some Selected Nigeria Dignifying Plants against Dematiaceous Fungi

Abstract

Dematiaceous fungal infections are the major threat facing farmers in Nigeria, as they are challenged with deformation of keratinized parts, destruction of soft tissues, economic losses and loss of interest in Agriculture. The available antifungal agents with minimal therapeutic measure are faced with strain resistance, adulteration, toxicity and also expensive. Hence this study focused on the quality of essential oils extracted from the fruits of Monodora myristica (MM) and rhizomes of Curcuma longa (CI) and its in vitro activity against dematiaceous fungi. The soil samples were randomly collected and screened for the presence of dematiaceous fungi using appropriate microbiological and molecular techniques. Gravimetric and instrumentational techniques were employed in extraction and characterization of essential oils extracted from the plant materials. Agar-welled diffusion was employed in determining the activities of the essential oils against the fungi.  Cladosporium sphaerospermum strain S11 (CSS1Q1), Curvularia lunata strain E31 (C1E31), Phomopsis azadirchtae strain T5 (PAT5) and Cladophialophora bantiana strain IL4059 (CBIL4059) were isolated from the soil samples. The essential oils (EO) contained pinene, terpinene, genaniol, cedrenes, cedrol, sapogenin, kaemferol, acetonitrile, and lunamarin. The physicochemical properties of EO extracted from MM and CI showed that the oils had edible and industrial potential. The in vitro activities of EO showed pronounced activities against the dematiaceous fungi, and EO from MM significantly (p<0.05) exhibited greater activity against the isolates than that from CL, and this was seen most against PAT5. The activities of EO extracted from CL were significantly (p<0.05) lower than the activities of Ketoconazole but that from MM were non significantly (p>0.05) higher than that of Ketoconazole. The study has shown that EO extracted from MM and CL conform to the stipulated standard, and were effective against CSS1Q1, CIE31, CBIL4059, and PAT5, of which EO from MM was more effective, mostly against PAT5.