ABSTRACT

A comparative study of the antifungal activities of the leaf extract of Mitracarpus hirtus, and the seed and leaf extracts of Garcinia kola was carried out using the Agar well diffusion method on five fungal isolates (Candida albicans, Penicillium marneffei, Microsporum canis, Rhizomucor pusillus and Aspergillus niger). Different concentrations of the plant extracts (50,100 and 200mg/ml) were used against the five pathogenic fungi. Data collected was subjected to t-test and Analysis of Variance (ANOVA). Means were separated by Duncan Multiple Range Test (DMRT) at p≤0.05. The results show that ethanol used as solvent was effective in extracting the active compounds. Results of the qualitative phytochemical compositions of seeds and leaves of G. kola and the leaves of M. hirtus showed the presence of bioactive compounds of interest such as alkaloids, tannins, flavonoids, saponins, phenols, anthraquinones, terpenoids, phlobatannins, steroids and glycosides. Results show that the extracts from leaf of Garcinia kola contained higher percentage of alkaloids (10.05±0.21), phenols (9.54±0.01) and flavonoids (4.80±0.14), than the leaf of M. hirtus (2.50±0.14, 8.10±0.02 and 3.97±0.03), and the seed of G. kola (0.83±0.05, 0.44±0.06 and 0.36±0.04) respectively. The leaf of M. hirtus contained higher percentage of tannins (7.61±0.01) than the leaf and seed of G. kola (2.83±0.03 and 1.34±0.05) respectively. The seed of G. kola contained higher percentage of saponins (5.52±0.05) than the leaves of M. hirtus and G. kola (2.81±0.05 and 2.25±0.35) respectively. The M. hirtus ethanol extract exhibited the best inhibitory activities against most of the test fungi, producing inhibition zones ranging from 12.05±0.07-17.99±0.01mm. There was resistance from Aspergillus niger. The G. kola seed extract also inhibited most of the test fungi. The inhibition zone observed ranged from 10.08±0.11-15.08±0.11mm. There was also resistance from Rhizomucor pusillus. M. hirtus leaf ethanolic extract significantly inhibited Candida albicans, while G. kola seed ethanolic extract also significantly inhibited Microsporum canis and Penicillium marneffei respectively. The activity index of ethanol extract of M. hirtus leaf (0.86 and 0.90 mm) was higher than that of G. kola seed (0.83 and 0.88 mm) when both fluconazole and ketoconazole were used as standard drugs. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of M. hirtus ethanolic leaf extract on the fungal isolates ranged from 6.25-12.5 mg/ml and 12.5-25 mg/ml respectively. The G. kola ethanolic seed extract has minimum inhibitory concentration (MIC) of 50 to 100 mg/ml and minimum fungicidal concentration (MFC) of 100 to 200 mg/ml respectively. Gas chromatography-mass spectrometry (GC-MS) analysis of the leaf and seed extracts of M. hirtus and G. kola was performed. The major constituents identified in ethanolic leaf extract of M. hirtus are 2,4-Di-tert-butylphenol (3.791%), 2-Octylcyclopropene-1-heptanol (6.230%), cis-11-Hexadecenal (2.179%), Cholestan-3-one,4,4-dimethyl-(5α) (4.154%). The major constituents identified in the ethanolic seed extract of G. kola are Hexadecanoic acid (11.276%), Octadecanoic acid (13.569%), n-Hexadecanoic acid (5.038%), l-(+)-Ascorbic acid 2,6-dihexadecanoate (2.444%), 4,7-Octadecadiynoic acid (2.996%), Falcarinol (4.419%) and 6-Octadecenoic acid (2.595%), which might be responsible for antifungal activity of ethanolic leaf and seed extracts of M. hirtus and G. kola. The implication of these results are discussed in relation to the antimicrobial activities of medicinal plants and the use of Garcinia kola seed and Mitracarpus hirtus leaf in treating some fungal infections affecting man.