Invitro Susceptibility Assay of Aqueous Fruit Extract of Vitex doniana for Antimethicillin Resistant Staphylococcus aureus Activity

摘要

The use of Vitexdoniana in herbal medicine has a long standing history. This research assessed the invitrosusceptibility of Methicillin Resistant Staphylococcus aureus (MRSA) to aqueous fruit extract of V. doniana.Proximate and phytochemical compositions of Vitex doniana fruit were determined and various concentrations ofthe aqueous extract tested for invitro antiMRSA activity, minimum inhibitory concentration (MIC) and minimumbactericidal concentration (MBC). V. doniana fruit has high lipid content of 31.40±1.24%/100g Dry Weight (DW)with fibre content of 0.90±0.10%/100g DW. Potassium, sodium, phosphorus, copper, magnesium and iron werepresent in the fruit with phosphorus accounting for 36% per 100g DW and copper accounting for 2.10±0.01%/100gDW. Zones of inhibition of aqueous V. doniana fruit extract against MRSA at 10mg/ml, 20 mg/ml, 30 mg/ml and40 mg/ml were 17.5±0.20mm, 22.0±0.02mm, 25.0±0.10mm and 28.0±0.45mm respectively. The zone of inhibitionof methicillin (30μg) was 6.0±0.23mm and that of vancomycin (30μg) was 37.6±0.10 mm. Against MethicillinSensitive Staphylococcus aureus (MSSA) at the same concentrations of 10 mg/ml, 20 mg/ml, 30 mg/ml and 40mg/ml, zones of inhibition of 17.0±0.13 mm, 23.0±0.40 mm, 24.5±0.11 mm and 29.0±0.20 mm were recorded,whereas 30μg methicillin (negative control) and 30μg vancomycin (positive control) zones of inhibition were36.0±0.21 mm and 38.0±0.11 mm respectively. The MIC of the extract against MRSA and MSSA was 250 μg/mlwhile the MBC was 500 μg/ml, values higher than 1.36 μg/ml MIC and 1.85 μg/ml MBC of methicillin and 0.49μg/ml MIC and MBC of vancomycin against MRSA. The MIC and MBC of methicillin and vancomycin againstMSSA were equal (0.24 μg/ml). Aqueous V. doniana fruit extract exhibited significant antimicrobial activityagainst MRSA (p>0.05), which increased proportionally with increase in concentration of the extract, although theMIC and MBC were high. Further research should be conducted to evaluate the invivo activity of the extract whileisolating the bioactive substance responsible for the observed invitro antiMRSA activity of the extract.