Nyambuya Tafadzwa, Mautsa Ruvimbo, Mukanganyama Stanley
School of Pharmacy, College of Health Sciences, University of Zimbabwe, Mt. Pleasant, Harare, Zimbabwe.
Department of Biochemistry, University of Zimbabwe, P.O. Box MP 167, Mt. Pleasant, Harare, Zimbabwe.
BMC Complement Altern Med. 2017 Feb 23;17(1):124. doi: 10.1186/s12906-017-1636-0.
Current tuberculosis regimens have failed to combat the issue of drug resistance and ethno medicines may represent a possible source of antimycobacterial agents. Combretum species are well known in African traditional medicines and used for various ailments including pneumonia, venereal diseases like syphilis, mental problems, relief of sore throats and colds, fever, and chest coughs associated with tuberculosis. Alkaloids function as either hydrogen-acceptor or hydrogen-donor in hydrogen bonding critical for the interaction between targets thus, potentiating effects of curative agents on diseases. Alkaloid extracts from leaves of Combretum zeyheri, Combretum platypetalum, Combretum molle and Combretum apiculatum, were assessed for antimycobacterial activity to establish rationale for their use in traditional medicines for various ailments including pneumonia, relief of sore throats and colds, fever, and chest coughs associated with tuberculosis.
Alkaloids were extracted from the leaves of Combretum zeyheri, Combretum platypetalum, Combretum molle and Combretum apiculatum. The broth microdilution method was used for the screening of growth inhibitory activity. The standard drug rifampicin was used as the positive control. Alkaloid extracts from the most potent plant species, Combretum zeyheri were further investigated for time-kill dependency effects on drug transport in Mycobacterium smegmatis.
Using the broth microdilution susceptibility method, C. zeyheri alkaloid extract, was found to have the most antimycobacterial effects with an MIC value of 125 μg/ml whilst MICs for C. molle and C. platypetalum were above 1000 μg/ml. An MBC value of 250 μg/ml was observed with alkaloid extracts from Combretum zeyheri whilst the remaining three Combretum species showed no bactericidal activity. It was also shown that C. zeyheri had potential efflux pump inhibitory activity. Determination of the time-kill kinetics of extracts from C. zeyheri showed not only a concentration-dependent activity but time-dependent bactericidal effect as well.
Alkaloid extracts from the leaves of C. zeyheri have potential as a source of lead compounds that may be developed further into antimycobacterial compounds. The mechanism of action of may be due to inhibition of transport across the cell membrane. Further work needs to be done to isolate the active components in these extracts.
当前的结核病治疗方案未能有效应对耐药性问题，民族药物可能是抗分枝杆菌药物的一个潜在来源。风车子属植物在非洲传统医学中广为人知，可用于治疗多种疾病，包括肺炎、梅毒等性病、精神问题、缓解喉咙痛和感冒、发烧以及与结核病相关的胸部咳嗽。生物碱在氢键中作为氢受体或氢供体发挥作用，这对于靶点之间的相互作用至关重要，从而增强了治疗剂对疾病的疗效。对泽氏风车子、阔瓣风车子、多毛风车子和尖果风车子叶片中的生物碱提取物进行抗分枝杆菌活性评估，以确定其在传统医学中用于治疗包括肺炎、缓解喉咙痛和感冒、发烧以及与结核病相关的胸部咳嗽等各种疾病的合理性。
从泽氏风车子、阔瓣风车子、多毛风车子和尖果风车子的叶片中提取生物碱。采用肉汤微量稀释法筛选生长抑制活性。标准药物利福平用作阳性对照。对最具活性的植物物种泽氏风车子的生物碱提取物进一步研究其对耻垢分枝杆菌药物转运的时间杀灭依赖性效应。
使用肉汤微量稀释药敏试验方法，发现泽氏风车子生物碱提取物具有最强的抗分枝杆菌作用，MIC值为125μg/ml，而多毛风车子和阔瓣风车子的MIC值高于1000μg/ml。泽氏风车子生物碱提取物的MBC值为250μg/ml，而其余三种风车子属植物未显示杀菌活性。还表明泽氏风车子具有潜在的外排泵抑制活性。泽氏风车子提取物的时间杀灭动力学测定表明，其不仅具有浓度依赖性活性，还具有时间依赖性杀菌作用。
泽氏风车子叶片中的生物碱提取物有潜力作为先导化合物的来源，可能进一步开发成抗分枝杆菌化合物。其作用机制可能是抑制跨细胞膜转运。需要进一步开展工作以分离这些提取物中的活性成分。
