Masoko Peter, Makgapeetja David M
Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Private bag X1106, Sovenga, 0727, South Africa.
BMC Complement Altern Med. 2015 Nov 17;15:409. doi: 10.1186/s12906-015-0941-8.
Olea africana leaves are used by Bapedi people to treat different ailments. The use of these leaves is not validated, therefore the aim of this study is to validate antimicrobial properties of this plant.
The ground leaves were extracted using solvents of varying polarity (hexane, chloroform, dichloromethane (DCM), ethyl acetate, acetone, ethanol, methanol, butanol and water). Thin layer chromatography (TLC) was used to analyse the chemical constituents of the extracts. The TLC plates were developed in three different solvent systems, namely, benzene/ethanol/ammonium solution (BEA), chloroform/ethyl acetate/formic acid (CEF) and ethyl acetate/methanol/water (EMW). The micro-dilution assay and bioautography method were used to evaluate the antibacterial activity of the extracts against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus and the antifungal activity against Candida albicans and Cryptococcus neoformans.
Methanol was the best extractant, yielding a larger amount of plant material whereas hexane yielded the least amount. In phytochemical analyses, more compounds were observed in BEA, followed by EMW and CEF. Qualitative 2, 2- diphenylpacryl-1-hydrazyl (DPPH) assay displayed that all the extracts had antioxidant activity. Antioxidant compounds could not be separated using BEA solvent system while with CEF and EMW enabled antioxidant compounds separation. The minimum inhibitory concentrations (MIC) values against test bacteria ranged between 0.16 and 2.50 mg/mL whereas against fungi, MIC ranged from 0.16 to 0.63 mg/mL. Bioautography results demonstrated that more than one compound was responsible for antimicrobial activity in the microdilution assay as the compounds were located at different Rf values.
The results indicate that leaf extracts of Olea africana contain compounds with antioxidant, antibacterial and antifungal activities. Therefore, further studies are required to isolate the active compounds and perform other tests such as cytotoxicity. Olea africana may be a potential source of antimicrobial compounds.
巴佩迪人用非洲油橄榄叶治疗各种疾病。但这些叶子的药用价值尚未得到验证，因此本研究旨在验证这种植物的抗菌特性。
用不同极性的溶剂（己烷、氯仿、二氯甲烷（DCM）、乙酸乙酯、丙酮、乙醇、甲醇、丁醇和水）提取研磨后的叶子。采用薄层色谱法（TLC）分析提取物的化学成分。TLC板在三种不同的溶剂系统中展开，即苯/乙醇/铵溶液（BEA）、氯仿/乙酸乙酯/甲酸（CEF）和乙酸乙酯/甲醇/水（EMW）。采用微量稀释法和生物自显影法评估提取物对大肠杆菌、铜绿假单胞菌、粪肠球菌和金黄色葡萄球菌的抗菌活性以及对白色念珠菌和新型隐球菌的抗真菌活性。
甲醇是最佳提取剂，能提取出较多的植物物质，而己烷提取出的量最少。在植物化学分析中，在BEA中观察到的化合物较多，其次是EMW和CEF。定性2,2-二苯基丙烯酰-1-肼基（DPPH）试验表明，所有提取物均具有抗氧化活性。使用BEA溶剂系统无法分离抗氧化化合物，而CEF和EMW能实现抗氧化化合物的分离。对测试细菌的最低抑菌浓度（MIC）值在0.16至2.50mg/mL之间，而对真菌的MIC值在0.16至0.63mg/mL之间。生物自显影结果表明，在微量稀释试验中，不止一种化合物具有抗菌活性，因为这些化合物位于不同的比移值（Rf）处。
结果表明，非洲油橄榄叶提取物含有具有抗氧化、抗菌和抗真菌活性的化合物。因此，需要进一步研究分离活性化合物并进行其他测试，如细胞毒性测试。非洲油橄榄可能是抗菌化合物的潜在来源。
