Antimicrobial Efficacy of Vitellaria paradoxa fractions and compounds on some wood Fungi and Bacteria

Abstract

This study examined antifungal efficacy of Vitellaria paradoxa fractions and compounds in the control of some wood degrading fungi. Stem bark and heartwood parts of Vitellaria paradoxa were collected, dried, pulverised and macerated sequentially in n- hexane, methanol and ethyl acetate solvents. The mixtures were filtered, evaporated and the dried samples were mixed and run over silica gel in column chromatography with a mixture of n -hexane and ethyl acetate solvents to obtain fractions. The fractions collected were evaporated and those with white needles were subjected to Magnetic Resonance (NMR) spectroscopic analysis. Spinasterol was isolated and characterised from the heartwood fraction while the stem bark fractions were fatty. Vitellaria paradoxa fractions were active against Serpula lacrymans, Sclerotium rolfsii, Aspergillus fumigatus, Fomitopsis pinicoca, Phaeolus schweinitzii, Rhizopus sp., Coniophora puteana, Gloeophyllum sepiarium, and Fibroporia vaillantii at zones of inhibition (ZOI) of 18 mm - 24 mm. Although the antibiotics were active (25 – 31 mm), they were found inactive against the Fomitopsis pinicoca fungus which was sensitive to all the V. paradoxa fractions at zones of inhibition of 18 - 24 mm. The minimum inhibitory concentrations (MIC) of the V. paradoxa fractions were active at 50 μg/mL against all test fungi. At minimum fungicidal concentration (MFC) of between 50 - 200 μg/mL, all the test fungi were killed. Based on the ZOI, MIC and MFC, the V. paradoxa stem bark heartwood fractions have been proven to be very efficient in inhibiting the growth of test wood rot fungi; hence the species could be explored as a potential source of bioactive fungicides.