Asres Kaleab, Mazumder Avijit, Bucar Franz
Department of Pharmacognosy, School of Pharmacy, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia.
Ethiop Med J. 2006 Jul;44(3):269-77.
In traditional medical practices of Ethiopia the aqueous extracts obtained from the stem bark of Combretum molle (R. Br. Ex. G. Don.) Engl & Diels (Combretaceae) have a longstanding reputation for the treatment of liver diseases malaria and tuberculosis. Owing to the widespread traditional uses of this plant, the studyinvestigated the antimicrobial activity the bark extract of this plant against Gram positive and and Gram negative bacteria.
Petroleum ether, dichloromethane and acetone fractions of the bark of the plant were prepared by soxhlet extraction and screened for their antimicrobial activity. The acetone fraction exhibited a powerful activity and was therefore further tested against twenty-one bacterial and six fungal strains. The minimum inhibitory concentration (MIC) of this extract was determined by checker board technique using nutrient agar medium. The zones of inhibition produced by the extract against bacteria and fungi were determined and compared by disc diffusion technique with those of pure ciprofloxacin and griseofulvin, respectively.
The highest antibacterial action of the acetone extract was against the Gram negative organisms EscherIchia coli and Shigella spp with an MIC value of 50 mg/ml. The activity of the extract against these bacteria was comparable to that of ciprofloxacin when assessed by the disc diffusion technique. Among the fungal strains tested Candida albicans showed high susceptibility to the extract and growth was completely inhibited at a concentration of 400 microg/ml. At the same concentration, the acetone extract and the standard antifungal drug griseofulvin produced comparable zones of inhibition on C. albicans. Studies on the mode of action of the extract indicated that it was bactericidal and fungicidal. The antimicrobial activity of the extract was attributed to the high amount of hydrolysable tannins present in the bark of the plant.
The acetone extract of the stem bark of C. molle has the potential for use as a natural antimicrobial agent. Further in vivo antimicrobial, phytochemical and toxicological studies are requireed to evaluate the chemotherapeutic effect of the plant.
在埃塞俄比亚的传统医学实践中，从柔毛风车子（Combretum molle (R. Br. Ex. G. Don.) Engl & Diels，使君子科）茎皮中提取的水提取物在治疗肝病、疟疾和结核病方面久负盛名。由于这种植物的广泛传统用途，本研究调查了该植物树皮提取物对革兰氏阳性菌和革兰氏阴性菌的抗菌活性。
通过索氏提取法制备该植物树皮的石油醚、二氯甲烷和丙酮馏分，并对其抗菌活性进行筛选。丙酮馏分表现出强大的活性，因此进一步针对21种细菌菌株和6种真菌菌株进行测试。使用营养琼脂培养基通过棋盘法测定该提取物的最低抑菌浓度（MIC）。通过纸片扩散法分别测定该提取物对细菌和真菌产生的抑菌圈，并与纯环丙沙星和灰黄霉素的抑菌圈进行比较。
丙酮提取物对革兰氏阴性菌大肠杆菌和志贺氏菌属的抗菌作用最强，MIC值为50mg/ml。通过纸片扩散法评估时，该提取物对这些细菌的活性与环丙沙星相当。在所测试的真菌菌株中，白色念珠菌对该提取物高度敏感，在浓度为400μg/ml时生长完全受到抑制。在相同浓度下，丙酮提取物和标准抗真菌药物灰黄霉素对白色念珠菌产生的抑菌圈相当。对提取物作用方式的研究表明它具有杀菌和杀真菌作用。提取物的抗菌活性归因于该植物树皮中存在的大量可水解单宁。
柔毛风车子茎皮的丙酮提取物有作为天然抗菌剂使用的潜力。需要进一步进行体内抗菌、植物化学和毒理学研究以评估该植物的化疗效果。
