Phytomedicine Programme, Department Paraclinical Sciences, Faculty Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
BMC Complement Altern Med. 2014 Aug 27;14:317. doi: 10.1186/1472-6882-14-317.
The study randomly screened leaf extracts of several hundred southern African tree species against important microbial pathogens to determine which taxa have the highest activity and may yield useful products to treat infections in the animal health market.
We determined the antibacterial and antifungal activity of 714 acetone leaf extracts of 537 different tree species against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Cryptococcus neoformans. A sensitive serial dilution microplate method was used.
Several extracts had MICs as low as 0.02 mg/ml. We analysed 14 out of the 38 tree orders where we determined the activity of more than 8 different tree species representing 89% of all species examined. There were statistically significant differences in some cases. Celastrales, Rosales and Myrtales had the highest activity against Gram-positive bacteria, the Myrtales and Fabales against the Gram-negative bacteria and the Malvales and Proteales against the fungi. Species present in the Asterales followed by the Gentiales and Lamiales had the lowest activities against all the microorganisms tested. Fabales species had the highest activities against all the microorganisms tested. There was substantial selectivity in some orders. Proteales species had very high activity against the fungi but very low activity against the bacteria. The species in the Celastrales and Rosales had very low antifungal activity, low activity against Gram-negative bacteria and very high activity against Gram-positive bacteria.
Against all classes of microorganisms, the four orders containing species with the highest average antimicrobial activities also contained several species with low activities against different pathogens and vice versa. These results therefore should be used with circumspection in selecting tree orders that would yield the highest probability of finding species with promising activities. Nevertheless there was a twofold increase in probability of finding extracts with interesting antifungal activity from orders with high mean activity than from orders with low mean activity. The probability increased to threefold and fivefold for Gram-positive and Gram-negative bacteria respectively.
本研究随机筛选了数百种南非树种的叶片提取物，以对抗重要的微生物病原体，以确定哪些类群具有最高的活性，并可能产生有用的产品来治疗动物健康市场中的感染。
我们测定了 537 种不同树种的 714 种丙酮叶提取物对粪肠球菌、金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌、白色念珠菌和新生隐球菌的抗菌和抗真菌活性。采用敏感的连续稀释微孔板法。
一些提取物的 MIC 低至 0.02mg/ml。我们分析了 38 个树目中的 14 个，这些树目确定了超过 8 种不同树种的活性，代表了所有检查的物种的 89%。在某些情况下存在统计学上的显著差异。Celastrales、Rosales 和 Myrtales 对革兰氏阳性菌的活性最高，Myrtales 和 Fabales 对革兰氏阴性菌的活性最高，Malvales 和 Proteales 对真菌的活性最高。在 Asterales 之后的 Gentianales 和 Lamiales 中，所有测试的微生物对所有测试的微生物的活性最低。Fabales 物种对所有测试的微生物都具有最高的活性。在某些目中有很大的选择性。Proteales 物种对真菌具有很高的活性，但对细菌的活性很低。Celastrales 和 Rosales 中的物种对真菌的抗真菌活性很低，对革兰氏阴性菌的活性低，对革兰氏阳性菌的活性很高。
针对所有类别的微生物，含有平均抗菌活性最高的物种的四个目也包含了一些对不同病原体活性较低的物种，反之亦然。因此，在选择最有可能发现具有潜在活性的物种的目时，应谨慎使用这些结果。然而，从高平均活性的目中找到具有有趣抗真菌活性的提取物的概率是从低平均活性的目中的两倍。对于革兰氏阳性菌和革兰氏阴性菌，这一概率分别增加到三倍和五倍。
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