Voukeng Igor K, Nganou Blaise K, Sandjo Louis P, Celik Ilhami, Beng Veronique P, Tane Pierre, Kuete Victor
Department of Biochemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
Department of Chemistry, Faculty of Science, University of Dschang, Dschang, Cameroon.
BMC Complement Altern Med. 2017 Jan 7;17(1):28. doi: 10.1186/s12906-016-1509-y.
Elaeophorbia drupifera (Thonn.) Stapf. (Euphorbiaceae) is used in Cameroonian folk medicine to treat several ailments including bacterial-related diseases such as skin infections. In this study, the methanol extract from the leaves (EDL), fractions (EDLa-d), sub-fractions EDLc1-7 and EDLc31-35 as well as isolated compounds were tested for their antimicrobial activities against a panel of Gram-negative and Gram-positive bacteria including multidrug resistant (MDR) phenotypes.
The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; column chromatography was used for the fractionation and purification of the leaves extract whilst the chemical structures of compounds were determined using spectroscopic techniques.
Phytochemical investigation lead to the isolation of a mixture (1:3) of stigmasterol and β-sitosterol (1 + 2), euphol (3), sitosterol-O-β- -xylopyranoside (4), 3,3',4'-tri-O-methylellagic acid (5), a mixture (1:1) of afzelin and quercetin-3-O-β--xylopyranoside (6 + 7), 3,3',4'-tri-O-methylellagic acid 4-O-β--glucopyranoside (8), ellagic acid-4-O-β-xylopyranoside-3,3',4'-trimethyl ether (9) from EDLc. Crude extract and fractions displayed selective activities with MIC values ranged from 32 to 1024 μg/mL for EDL against 84.9% of the 33 tested bacteria, 93.9% for EDLc, 69.7% for EDLb, 33.4% for EDLa and 0.03% for EDLd. MIC values ranged from 16 to 1024 μg/mL were obtained with EDLc3 and EDLc4 on all tested bacteria meanwhile other sub-fractions displayed selective activities. MIC value of 32 μg/mL was obtained with fractions EDLa against Escherichia coli AG100, EDLc against Enterobacer aerogenes ATCC13048 and EA298. For sub-fractions obtained from EDLc, the lowest MIC value of 16 μg/mL was recorded with EDLc3 against Staphylococcus aureus MRSA11. A corresponding value of 8 μg/mL against Providencia stuartii NAE16 was recorded with EDLc33 obtained from further fractionation of EDLc3. EDLc3 had MIC values below 100 μg/mL against all tested bacteria. Compound 5 as well as the mixture (1:1) of 6 and 7 inhibited the growth of all the tested bacteria with MICs ranged from 64 to 256 μg/mL.
Elaeophorbia drupifera is a potential source of phytomedicine to tackle MDR bacteria. Sub-fraction EDLc3 was more active than all isolated compounds and deserves further investigations to develop natural drug to combat Gram-negative, Gram-positive bacteria and otherwise MDR phenotypes.
油桐大戟（Elaeophorbia drupifera (Thonn.) Stapf.，大戟科）在喀麦隆民间医学中用于治疗多种疾病，包括与细菌相关的疾病，如皮肤感染。在本研究中，测试了叶的甲醇提取物（EDL）、馏分（EDLa - d）、亚馏分EDLc1 - 7和EDLc31 - 35以及分离出的化合物对一组革兰氏阴性和革兰氏阳性细菌（包括多重耐药（MDR）表型）的抗菌活性。
采用肉汤微量稀释法测定上述样品的最低抑菌浓度（MIC）和最低杀菌浓度（MBC）；柱色谱法用于叶提取物的分离和纯化，同时使用光谱技术确定化合物的化学结构。
植物化学研究从EDLc中分离出豆甾醇和β - 谷甾醇的混合物（1:3）（1 + 2）、大戟醇（3）、谷甾醇 - O - β - D - 木糖苷（4）、3,3',4'-三 - O - 甲基鞣花酸（5）、阿福豆苷和槲皮素 - 3 - O - β - D - 木糖苷的混合物（1:1）（6 + 7）、3,3',4'-三 - O - 甲基鞣花酸4 - O - β - D - 葡萄糖苷（8）、鞣花酸 - 4 - O - β - 木糖苷 - 3,3',4'-三甲醚（9）。粗提取物和馏分表现出选择性活性，EDL对33种测试细菌中84.9%的MIC值范围为32至1024μg/mL，EDLc为93.9%，EDLb为69.7%，EDLa为33.4%，EDLd为0.03%。EDLc3和EDLc4对所有测试细菌的MIC值范围为16至1024μg/mL，同时其他亚馏分表现出选择性活性。EDLa对大肠杆菌AG100、EDLc对产气肠杆菌ATCC13048和EA298的MIC值为(32μg/mL)。对于从EDLc获得的亚馏分，EDLc3对金黄色葡萄球菌MRSA11的最低MIC值为 (16μg/mL)。从EDLc3进一步分离得到的EDLc33对斯氏普罗威登斯菌NAE16的相应值为(8μg/mL)。EDLc3对所有测试细菌的MIC值均低于 (100μg/mL)。化合物5以及6和7的混合物（1:1）抑制所有测试细菌的生长，MIC值范围为64至256μg/mL。
油桐大戟是应对多重耐药细菌的潜在植物药来源。亚馏分EDLc3比所有分离出的化合物活性更强，值得进一步研究以开发对抗革兰氏阴性、革兰氏阳性细菌及其他多重耐药表型的天然药物。
