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Tanzania Journal of Health Research, Vol. 10, No. 1, January, 2008, pp. 34-38 An antifungal property of crude plant extracts from Anogeissus leiocarpus and Terminalia avicennioides A. MANN*, A. BANSO and L.C. CLIFFORD Department of Science Laboratory Technology, The Federal Polytechnic, P.M.B. 55, Bida, Niger State, Nigeria Received 12 September 2007 Revised 10 October 2007 Accepted 12 October 2007 Code Number: th08007 Abstract Chloroform, ethanolic, methanolic, ethyl acetate and aqueous root extracts of Anogeissus leiocarpus and Terminalia avicennioides were investigated in vitro for antifungal activities against Aspergillus niger, Aspergillus fumigatus, Penicillium species, Microsporum audouinii and Trichophyton rubrum using radial growth technique. The plant extracts inhibited the growth of all the test organisms. The minimum inhibitory concentration (MIC) of the extracts ranged between 0.03μg/ml and 0.07μg/ml while the minimum fungicidal concentration ranged between 0.04μg/ml and 0.08μg/ml. Anogeissus leiocarpus appears to be more effective as an antifungal agent than Terminalia avicennioides. Ethanolic extracts of the two plant roots were more effective than the methanolic, chloroform, or aqueous extracts against all the test fungi. Key words: Anogeissus leiocarpus, Terminalia avicennioides, extracts, inhibitory, fungicidal, Nigeria Introduction Many of the plant materials used in traditional medicine are readily available in rural areas and this has made traditional medicine relatively cheaper than modern medicine (Apulu et al., 1994). Over Sixty percent of Nigeria rural population depends on traditional medicine for their healthcare need (Apulu et al., 1994). Medicinal properties of plants are normally dependent on the presence of certain phytochemical principles such as alkaloids, anthraquinones, cardiac glycosides, saponins, tannins and polyphenols which are the bioactive bases responsible for the antimicrobial property (Ebana et al., 1993). Medicinal plants contain pharmacologically active principles which over the years have been exploited in traditional medical practice for the treatment of various ailments (Adebanjo et al., 1983). Villegas et al. (1988) studied the constituents of African medicinal plants and found that a petroleum ether extract of Heteromopha trifoliateleaves had antifungal properties against Cladosporium cuicumerimum. A number of Combretaceae species tested for antifungal activity showed promising results. Among the seven species tested, Combretum nigrican was strongly active on dermatophytes (Baba-Moussa, 1998). Sodipo et al. (1991) carried out susceptibility test using Garcinia kola and found the seed to have fungistatic action on Aspergillus niger. Amer et al. (1991) conducted test on the effect of aqueous garlic extract on the growth of dermatophytes and the extract was found to have inhibitory effect on the growth of Microsporum species, Trychophyton verrucosam and Trychophyton rubrum. The ethanolic extract of Tagetes lucida showed antifungal activity against Candida albicans (Caceres et al., 1998). Sodipo et al. (1991) reported that the essential oil of Aframomum melagulatus fruit inhibited the mycelia growth of Trichophyton mentagrophytes at a pronounced rate but the inhibitory concentration obtained against Aspergillus niger was lower. Since medicinal plants play a paramount role in the management of various ailments in rural communities, there is therefore, a need for scientific verification of their activities against fungi. Currently, there is little evidence on the antimicrobial properties of these plants under investigation against majority of fungi. The objective of this study was to assay the root extracts of Anogeissus leiocarpus and Terminalia avicennioides for their antifungal activities. Materials and Methods Plant material The roots of Anogeissus leiocarpus and Terminalia avicennioides used in this study were collected in Bida, Niger State, Nigeria. The plants were identified by Muhammad Musa of the Department of Biological Sciences, Ahmadu Bello University (ABU), Zaria, Nigeria and Ibrahim Muazzami of the National Institute for Pharmaceutical Research and Development (NIPRD), Idu Abuja, Nigeria; in accordance with the criteria stipulated by international committee for botanical nomenclature. Voucher specimens of Anogeissus leiocarpus and Terminalia avicennioides were deposited in the Herbarium at the Department of Biological Sciences, ABU, Zaria, Nigeria and NIPRD, IduAbuja, Nigeria with the Herbarium numbers ABUH167 and NIPRDH5735, respectively. Test microorganisms The microorganisms used in this study were Aspergillus niger, Aspergillus fumigatus, Penicillium species and were isolated from patients at Federal Medical Centre, Bida, Niger State, Nigeria. Microsporum audouinii (PTCC 5060) and Trichophyton rubrum (PTCC 5069) were obtained from Microbiology Laboratory, Federal Polytechnic, Bida. Drying of plant parts and preparation of the plant extracts The plant parts were air dried at room temperature for two weeks. The dried plant parts were ground into powder form, sieved and packaged into polyethylene bags until when needed. 50g sample of the powdered dried roots of Anogeissus leiocarpus and Terminalia avicennioides were weighed separately into 200ml ethanol, methanol, chloroform, distilled water and ethyl acetate and then percolated for 24hrs. The extracts were then filtered through a millipore filter into different conical flasks. The extracts obtained were evaporated to dryness using a rotary evaporator. The extracts were assayed against the test organisms to determine the antifungal properties. Determination of antifungal properties of extracts The antifungal properties of the extracts were determined using the radial growth method (Banso et al., 1999). 0.02mg/ml (w/v) of the extracts were introduced into McCartney bottles containing 18ml of sterile potato dextrose agar. The mixture was poured into different petri dishes and allowed to solidify. The plates were inoculated with 5mm diameter of the fungal culture. Control experiment was performed without the extracts. Plates were incubated at 25oC for 72 hours. Antifungal activities were expressed in terms of diameter of growth. Determination of Minimum Inhibitory Concentration (MIC) Various concentrations (0.01μg/ml, 0.02μg/ml, 0.03μg/ml, 0.06μg/ml and 0.08μg/ml) of the extracts were prepared. Each of these was added to 18ml of malt extract in test tubes. Each tube was then inoculated with 0.1ml of the spore suspension of A. niger, A. fumigatus, Penicillin species, M. audouinii and T. rubrum diluted to give a final spore suspension of 106 spores per ml. The tubes were incubated at 28 oC ± 2oC and examined for growth after 7 days. The least concentration of the plant extracts that does permit any visible growth of the inoculated test organism in the broth medium was regarded as the MIC in each case. Control experiments were performed without the plant extracts. Determination of Minimum Fungicidal Concentration (MFC) of the extracts The contents of the tubes that showed no visible fungal growth or turbidity in the minimum inhibitory concentration experiment were cultured into fleshy prepared potato dextrose agar plate to assay for the fungicidal effect of the extracts. The plates containing the test organisms were incubated at 25oC for 15days. The minimum fungicidal concentration was regarded as the lowest concentration that did not yield any fungal growth on the solid medium used. Results Aqueous, ethanolic, methanolic, chloroform and ethyl acetate extracts of Anogeissus leiocarpus and Terminalia avicennioides exhibited antifungal activity against A. niger, A. fumigatus, Penicillium species, M. audouinii and T. rubrum (Tables 1 and 2). The largest growth diameters ranging from 10.5 ± 0.2mm to 19.2 ± 0.1mm were obtained from the assay containing aqueous extracts (Table 1), while the lowest ranges of mean diameters of growth (5.2 ± 0.2mm to 13.3 ± 0.1mm) were obtained with ethanolic extracts. T. rubrum appeared to be the most resistant to the effect of the root extracts of Terminalia avicennioides and Anogeissus leiocarpus while Penicillium species which had lower ranges of mean diameter of growth (5.2 ± 0.2mm to 14.0 ± 0.3mm) appeared to be the most susceptible (Table 1). Lower ranges of mean growth diameters (5.2 ± 0.2mm to 18.1 ± 0.5mm) were recorded against Anogeissus leiocarpus while higher ranges of mean growth diameters (7.01 ± 0.1mm to 19.2 ± 0.1mm) were obtained against Terminalia avicennioides and Anogeissus leiocarpus. The MIC of Terminalia avicennioides root extract The minimum fungicidal concentration of the against the test fungi ranged between 0.03μg/ml and extracts of T. avicennioides proved to posses more 0.07μg/ml. Ethanolic extract has the lowest MIC fungicidal action against Penicillium species when when tested against the test fungi while aqueous the extract was assayed (Table 3). This was indicated extract has the highest MIC (Table 2). The MIC of Anogeissus leiocarpus root extracts against the test fungi ranged been 0.3µg/ml and 0.06µg/ml. The MIC of ethanolic, methanolic, chloroform, aqueous and ethyl acetate extracts of Anogeissus leiocarpus against M.audouinii were 0.03µg/ml, 0.06µg/ml and 0.05µg/ml respectively (Table 2). The minimum fungicidal concentration of the extracts of T. avicennioides proved to posses more fungicidal action against Penicillium species when the extract was assayed (Table 3). This was indicated by the low values obtained in assays with methanolic, chloroform, aqueous and ethyl acetate root extracts of T. avicennioides against Penicillium species (Table 3). Aqueous root extract of T. avicennioides possess the lowest fungicidal action against A. niger among the extracts assayed against the organism with minimum fungicidal concentration of 0.08µg/ml (Table 3). Methanolic extract of A. leiocarpus was the most active fungicidal against A. niger with minimum fungicidal concentration of 0.04µg/ml. Relatively higher value of minimum fungicidal concentration were obtained in assays with ethanolic, chloroform, aqueous and ethylacetate root extracts of A. leiocarpus (Table 4) Discussion Antifungal test of aqueous, ethanolic, methanolic, chloroform and ethyl acetate extracts of Terminalia avicennioides and Anogeissus leiocarpus showed that the plants exhibit antifungal activity against A. niger, A. fumigatus, Penicillium species, M. audouinii and T. rubrum. It was revealed in this study, that increase in the antifungal activity of the extracts was enhanced by increase in the concentration of the extracts. This finding agrees with the report of Banso et al. (1999) that higher concentration of antimicrobial substance showed appreciation in growth inhibition. The fact that the results of this study showed that root extracts of Terminalia avicennioides and Anogeissus leiocarpus exhibit antifungal properties justifies their traditional use as medicinal plants. This may be due to the presence of active principles in the plant materials. Plants generally produce many secondary metabolites which constitute an important source of microbicides, pesticides and many pharmaceutical drugs (Oguntipe et al., 1998, Ibrahim et al., 1997). Plant products still remain the principal source of pharmaceutical agents used in orthodox medicine (Ibrahim et al., 1997; Oguntipe et al., 1998). The minimum inhibitory concentration values of the pant extracts against the test organisms showed that fungi vary widely in the degree of their susceptibility to antifungal agents. This agrees with the report that antimicrobial agents with low activity against an organism have high minimum inhibitory concentration while a highly antimicrobial agent has a low minimum inhibitory concentration (Banso et al., 1999; Prescott et al., 2002). When the broth culture of the extract and the test organisms used in the minimum inhibitory concentration tests were subcultured on a solid medium for the assessment of the minimum fungicidal concentrationof the extracts, the result indicated that the minimum fungicidal concentration of the extracts were obtained at higher concentrations than in the minimum inhibitory concentration studies. This observation therefore suggests that the antifungal substances contained in the extracts were fungistatic at lower concentrations while becoming fungicidal at higher concentrations of the extracts. Similar observations have been reported by Banso & Adeyemo (2000). In conclusion, the results obtained from this study shows that the ethanolic, methanolic, ethylacetate, chloroform and aqueous root extracts of Anogeissus leiocarpus and Terminalia avicennioides used in this study exhibit antifungal effect on the test organisms. Extracts of the plant used in this study could be useful in the treatment of fungal infections. References
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