Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
Integrated Chemical BioPhysic Research, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
PLoS One. 2021 May 10;16(5):e0251534. doi: 10.1371/journal.pone.0251534. eCollection 2021.
Melicope glabra (Blume) T. G. Hartley from the Rutaceae family is one of the richest sources of plant secondary metabolites, including coumarins and flavanoids. This study investigates the free radical scavenging and antibacterial activities of M. glabra and its isolated compounds. M. glabra ethyl acetate and methanol extracts were prepared using the cold maceration technique. The isolation of compounds was performed with column chromatography. The free radical scavenging activity of the extracts and isolated compounds were evaluated based on their oxygen radical absorbance capacity (ORAC) activities. The extracts and compounds were also subjected to antibacterial evaluation using bio-autographic and minimal inhibitory concentration (MIC) techniques against two oral pathogens, Enterococcus faecalis and Streptococcus mutans. Isolation of phytoconstituents from ethyl acetate extract successfully yielded quercetin 3, 5, 3'-trimethyl ether (1) and kumatakenin (2), while the isolation of the methanol extract resulted in scoparone (3), 6, 7, 8-trimethoxycoumarin (4), marmesin (5), glabranin (6), umbelliferone (7), scopoletin (8), and sesamin (9). The study is the first to isolate compound (1) from Rutaceae plants, and also the first to report the isolation of compounds (2-5) from M. glabra. The ORAC evaluation showed that the methanol extract is stronger than the ethyl acetate extract, while umbelliferone (7) exhibited the highest ORAC value of 24 965 μmolTE/g followed by glabranin (6), sesamin (9) and scopoletin (8). Ethyl acetate extract showed stronger antibacterial activity towards E. faecalis and S. mutans than the methanol extract with MIC values of 4166.7 ± 1443.4 μg/ml and 8303.3 ± 360.8 μg/ml respectively. Ethyl acetate extract inhibited E. faecalis growth, as shown by the lowest optical density value of 0.046 at a concentration of 5.0 mg/mL with a percentage inhibition of 95%. Among the isolated compounds tested, umbelliferone (7) and sesamin (9) exhibited promising antibacterial activity against S. mutans with both exhibiting MIC values of 208.3 ± 90.6 μg/ml. Findings from this study suggests M. glabra as a natural source of potent antioxidant and antibacterial agents.
桃金娘科白饭树属植物白饭树（Blume）T.G.哈特利是植物次生代谢产物，包括香豆素和类黄酮的最丰富来源之一。本研究调查了白饭树及其分离化合物的自由基清除和抗菌活性。采用冷浸渍技术从白饭树的乙酸乙酯和甲醇提取物中提取化合物。采用柱色谱法对化合物进行分离。根据其氧自由基吸收能力（ORAC）活性评价提取物和分离化合物的自由基清除活性。采用生物自显影和最小抑菌浓度（MIC）技术，对两种口腔病原体粪肠球菌和变形链球菌进行提取物和化合物的抗菌评价。从乙酸乙酯提取物中分离出的植物成分成功地得到了槲皮素 3,5,3'-三甲醚（1）和kumatanekin（2），而从甲醇提取物中分离出的则是scoparone（3）、6,7,8-三甲氧基香豆素（4）、marmesin（5）、glabranin（6）、umbelliferone（7）、scopoletin（8）和sesamin（9）。该研究首次从芸香科植物中分离出化合物（1），也是首次从白饭树中分离出化合物（2-5）。ORAC 评价表明，甲醇提取物比乙酸乙酯提取物强，而 Umbelliferone（7）表现出最高的 ORAC 值 24965μmolTE/g，其次是 Glabranin（6）、Sesamin（9）和 Scopoletin（8）。乙酸乙酯提取物对粪肠球菌和变形链球菌的抗菌活性强于甲醇提取物，MIC 值分别为 4166.7±1443.4μg/ml 和 8303.3±360.8μg/ml。乙酸乙酯提取物抑制粪肠球菌生长，在浓度为 5.0mg/ml 时，最低光密度值为 0.046，抑制率为 95%。在所测试的分离化合物中，umbelliferone（7）和 sesamin（9）对变形链球菌表现出有希望的抗菌活性，MIC 值均为 208.3±90.6μg/ml。本研究结果表明，白饭树是一种具有强大抗氧化和抗菌活性的天然来源。
