Bhunu Benjamin, Mautsa Ruvimbo, Mukanganyama Stanley
Bio-molecular Interactions Analyses Group, Department of Biochemistry, University of Zimbabwe, P.O. Box MP 167, Mt. Pleasant, Harare, Zimbabwe.
BMC Complement Altern Med. 2017 May 30;17(1):285. doi: 10.1186/s12906-017-1801-5.
Tuberculosis (TB) is a serious public health problem worldwide. Mycobacterium tuberculosis (M. tuberculosis) grows as drug tolerant pellicles. Agents that inhibit biofilm formation in M. tuberculosis have the potential to reduce the disease treatment period and improve the quality of tuberculosis chemotherapy. Parinari curatellifolia (P. curatellifolia) leaf extracts are claimed to treat symptoms similar to tuberculosis in ethnomedicinal practices. Mycobacterium smegmatis (M. smegmatis) is a surrogate organism used in antimycobacterial drug discovery assays. In this study, the effect of the leaf extracts of P. curatellifolia on M. smegmatis growth and biofilm formation was investigated in order to determine the basis of its use in traditional medicinal use.
Phytochemicals from P. curatellifolia leaves were prepared using a mixture of 50% dichloromethane (DCM): 50% methanol and by serial exhaustive extraction using different solvents of decreasing polarity. The solvents were used in the following order, hexane > dichloromethane > ethyl acetate > acetone >ethanol > methanol > water. The micro-broth dilution method was used as an antimycobacterial susceptibility test to screen for the extract that effectively inhibited M. smegmatis growth and biofilm formation. Biofilm quantification was performed by staining the biofilms with crystal violet and determining the amount of the stain using a spectrophotometer. In addition, the effects of combining the most active extract with kanamycin were also investigated.
The minimum inhibitory concentrations (MIC) of the extracts were found to be 6.2 μg/ml for the acetone extract, 12.5 μg/ml for both the ethanol and the total extract and 50 μg/ml for both the methanol and ethyl acetate extracts. The ethanol extract, dichloromethane extract and water extract were the only extracts that effectively inhibited biofilm formation in M. smegmatis. Combining the ethanol extract with kanamycin enhanced the effect of the ethanol extract in terms of inhibition of biofilm formation.
P. curatellifolia leaves contain phytochemicals that have the potential to be used both as antimycobacterial and anti-biofilm formation compounds.
结核病是全球严重的公共卫生问题。结核分枝杆菌以耐药菌膜形式生长。抑制结核分枝杆菌生物膜形成的药物有可能缩短疾病治疗周期并提高结核病化疗质量。在民族医学实践中，柯拉塔叶提取物据称可治疗与结核病相似的症状。耻垢分枝杆菌是抗分枝杆菌药物发现试验中使用的替代生物体。在本研究中，研究了柯拉塔叶提取物对耻垢分枝杆菌生长和生物膜形成的影响，以确定其在传统医学应用中的依据。
采用50%二氯甲烷（DCM）：50%甲醇的混合物，并通过使用极性递减的不同溶剂进行连续彻底萃取，制备柯拉塔叶的植物化学物质。按以下顺序使用溶剂：己烷>二氯甲烷>乙酸乙酯>丙酮>乙醇>甲醇>水。采用微量肉汤稀释法作为抗分枝杆菌药敏试验，筛选有效抑制耻垢分枝杆菌生长和生物膜形成的提取物。通过用结晶紫对生物膜进行染色并用分光光度计测定染色量来进行生物膜定量。此外，还研究了将活性最强的提取物与卡那霉素联合使用的效果。
提取物的最低抑菌浓度（MIC）分别为：丙酮提取物6.2μg/ml，乙醇提取物和总提取物均为12.5μg/ml，甲醇提取物和乙酸乙酯提取物均为50μg/ml。乙醇提取物、二氯甲烷提取物和水提取物是仅有的能有效抑制耻垢分枝杆菌生物膜形成的提取物。将乙醇提取物与卡那霉素联合使用可增强乙醇提取物在抑制生物膜形成方面的效果。
柯拉塔叶含有具有抗分枝杆菌和抗生物膜形成化合物潜力的植物化学物质。
