Abstract：
Medicinal plants are known as sources of potential antimicrobial compounds belonging to different classes. The aim of the present work was to evaluate the antimicrobial potential of the crude extract, fractions, and some isolated secondary metabolites from the leaves of Macaranga occidentalis, a Cameroonian medicinal plant traditionally used for the treatment of microbial infections. Repeated column chromatography of the ethyl acetate and n-butanol fractions led to the isolation of seventeen previously known compounds (1-17), among which three steroids (1-3), one triterpene (4), four flavonoids (5-8), two stilbenoids (9 and 10) four ellagic acid derivatives (11-14), one geraniinic acid derivative (15), one coumarine (16), and one glyceride (17). Their structures were elucidated mainly by means of extensive spectroscopic and spectrometric (1D and 2D NMR and, MS) analysis and comparison with the published data. The crude extract, fractions, and isolated compounds were all screened for their antimicrobial activity. None of the natural compounds was active against Candida strains. However, the crude extract, fractions, and compounds showed varying levels of antibacterial properties against at least one of the tested bacterial strains, with minimal inhibitory concentrations (MICs) ranging from 250 to 1000 μg/mL. The n-butanol (n-BuOH) fraction was the most active against Escherichia coli ATCC 25922, with an MIC value of 250 μg/mL. Among the isolated compounds, schweinfurthin B (10) exhibited the best activity against Staphylococcus aureus NR 46003 with a MIC value of 62.5 μg/mL. In addition, schweinfurthin O (9) and isomacarangin (6) also exhibited moderate activity against the same strain with a MIC value of 125 μg/mL. Therefore, pharmacomodulation was performed on compound 6 and three new semisynthetic derivatives (6a-c) were prepared by allylation and acetylation reactions and screened for their in vitro antimicrobial activity. None of the semisynthetic derivatives showed antimicrobial activity against the same tested strains. The chemophenetic significance of the isolated compounds is also discussed in this paper.
摘要：
已知药用植物是属于不同类别的潜在抗微生物化合物的来源。本工作的目的是评估粗提物的抗菌潜力，分数，和一些从西花马卡兰叶分离的次生代谢产物，传统上用于治疗微生物感染的喀麦隆药用植物。乙酸乙酯和正丁醇馏分的重复柱色谱导致17种先前已知的化合物（1-17）的分离，其中三个类固醇（1-3），一个三萜（4），四种类黄酮（5-8），两种二苯乙烯（9和10）四种鞣花酸衍生物（11-14），一种香叶酸衍生物（15），一个库马（16），和一种甘油酯（17）。它们的结构主要通过广泛的光谱和光谱测定（1D和2DNMR和，MS)分析并与公布的数据进行比较。粗提物,分数，和分离的化合物都进行了抗菌活性的筛选。没有一种天然化合物对念珠菌菌株具有活性。然而,粗提物,分数，和化合物对至少一种测试的细菌菌株显示出不同水平的抗菌特性，最小抑制浓度（MIC）范围为250至1000μg/mL。正丁醇(n-BuOH)级分对大肠杆菌ATCC25922最具活性,MIC值为250μg/mL。在分离的化合物中，schweinfurthinB（10）对金黄色葡萄球菌NR46003表现出最佳活性，MIC值为62.5μg/mL。此外,schweinfurthinO（9）和isomacarangin（6）对同一菌株也表现出中等活性，MIC值为125μg/mL。因此,对化合物6进行药物调节，并通过烯丙基化和乙酰化反应制备三种新的半合成衍生物（6a-c），并筛选其体外抗菌活性。没有一种半合成衍生物对相同的测试菌株显示出抗微生物活性。本文还讨论了分离化合物的化学表型意义。
