Some pharmacological activities of selected medicinal plant species used for treating cattle diseases in Kabira Sub-County, Rakai District

Abstract

The study was undertaken with an overall objective of investigating use of medicinal plants in traditional management of cattle conditions / diseases with emphasis on helminthiasis and bacterial related infections in Kabira Sub-county, Rakai district. Life forms of the medicinal plant species, habitats of harvest and levels of harvest were observed and recorded. With respect to the overall objective, prioritization of key medicinal plant species as used in managing both helminthiasis and bacterial related infections was done using Participatory pair wise ranking technique. Methanolic extracts of priority medicinal plants that were tested in-vitro against helminthiasis (Ascaris suum) and bacterial related infections showed the following results. Among the four tested medicinal plant extracts, against A. suum, Clerodendrum rotundifolium Oliv. and Carissa edulis (Forssk.) Vahl. showed biological activity of more than 50% mortality rate at concentration of 1.2 mg/ml and 1.6 mg/ml respectively. The percentage mortality rates were 1 to 3 times higher compared to extracts of Myrica kandtiana Engl. and Erythrina abyssinica Lam. ex D.C. At intervals of 36 hours and 48 hours, C. edulis had the greatest percentage mortality rate overall, followed by C. rotundifolium. E. abyssinica had the lowest activity at 36 hours. However, both M. kandtiana and E. abyssinica showed comparably similar mortality rates at 48 hours for concentration of 1.2 mg/ml and 1.6 mg/ml. Variability in percentage mortality rates for the two medicinal plants was observed at concentration of 0.8 mg/ml, where Myrica kandtiana had a mortality rate one time higher than of E. abyssinica at both 36 hours and 48 hours. The standard drug (albendazole), had a higher percentage mortality rate of 12.5% against C.edulis and C .rotundifolium at 0.8 mg/ml at both 36 hours and 48 hours. At 1.2 mg/ml (albendazole) and C. edulis had similar mortality, while for C. rotundifolium mortality of less than 12.5% compared to albendazole was observed at 48 hours. At 1.6 mg/ml, albendazole, C. rotundifolium and Myrica kandtiana had 100% mortality at 36 hours and 48 hours, while for C.edulis and E.abyssinica less than 12.5% mortality was observed compared to albendazole at 36 hours interval. All the three bacterial species were susceptible to only four methanolic extracts of M.kandtiana, Entada abyssinica Steud ex D.C, Rubus steudneri Schweinf. and Solanum aculeastrum Dunal. Staphylococcus aureus and Escherichia coli were susceptible to Sesamum anguistifolium (Oliv.) Engl. and Sapium ellipticum (Hoscht.) Pax., while restricted activity to Staphylococcus aureus was observed with Erythrina abyssinica. Overall, Rubus steudneri showed the highest level of susceptibility, followed by Entada abyssinica and then Myrica kandtiana, Sesamum anguistifolium and Erythrina abyssinica had the least activity. Comparison of the standard drug (gentamycin) with methanolic extracts of all the seven medicinal plant species, only showed relatively similar levels of susceptibility with Rubus steudneri. Overall Rubus steudneri and Erythrina abyssinica had the lowest MIC values, 0.03125 µg/ml similar to that of the standard drug (gentamycin). Thus, the two methanolic extracts had the highest biological activity against Staphylococcus aureus and Pseudomonas auroginosa. Consequently Myrica kandtiana and Entada abyssinica had MIC value of 0.0625 µg/ml against Staphylococcus aureus and Pseudomonas auroginosa. With 0.0625 µg/ml which was the second least concentration to 0.03125 µg/ml for the standard drug, Myrica kandtiana, Entada abyssinica, Rubus steudneri and Erythrina abyssinica were more potent compared to the medicinal plant abyssinica extracts of Solanum aculeastrum, Sesamum anguistifolium and Sapium ellipticum with high MIC values above 0.0625 µg/ml. For E.coli growth, 0.0625 µg/ml was observed as the least MIC for Myrica kandtiana, Solanum aculeastrum, Sesamum anguistifolium and Sapium, an indication that the four plant extracts had the highest activity against this test bacterium. The in-vitro studies of methanolic extracts of the selected medicinal plant species on Ascaris suum and the three species of bacteria were conducted as a preliminary proof to support their use in traditional management of both helminthiasis and bacterial related infections.