Zihad S M Neamul Kabir, Hasan Md Towhid, Sultana Mst Sabiha, Nath Sushmita, Nahar Lutfun, Rashid Mohammad A, Uddin Shaikh Jamal, Sarker Satyajit D, Shilpi Jamil A
Pharmacy Discipline, Life Science School, Khulna University, Khulna 9208, Bangladesh.
Department of Pharmacy, State University of Bangladesh, Dhaka 1205, Bangladesh.
Evid Based Complement Alternat Med. 2022 Apr 22;2022:9600079. doi: 10.1155/2022/9600079. eCollection 2022.
The Sundarbans, a UNESCO world heritage site, is one of the largest mangrove forests in one stretch. Mangrove plants from this forest are little studied for their endophytic fungi. In this study, we isolated fourteen endophytic fungi from the plants and collected from the Sundarbans. Five of them were identified as sp. and one as sp. by macroscopic and microscopic observation. Antibacterial activity of the crude extracts obtained from these endophytes was determined against , , , and using resazurin-based microtiter assay. The isolated endophytes showed varying degrees of antibacterial activity with MICs ranging between 5 and 0.078 mg/mL. Molecular identification of the most active endophyte revealed its identity as obtained from the leaves of . . Acute toxicity study of the ethyl acetate extract of . in mice revealed no mortality even at the highest dose of 2000 mg/kg bodyweight, though some opposing results are found in the subacute toxicity study. The extract was subjected to silica gel and Sephadex column chromatography resulting in the isolation of three pure compounds. LC-MS analysis of these pure compounds revealed their identity as fumigaclavine C, azaspirofuran B, and fraxetin. This is the first report of fraxetin from . . All three identified compounds were previously reported for their antibacterial activity against different strains of both Gram-positive and Gram-negative bacteria. Therefore, the observed antibacterial activity of the ethyl acetate (EtOAc) extract of . could be due to the presence of these compounds. These results support the notion of investigating fungal endophytes from the Sundarbans for new antimicrobial compounds.
孙德尔本斯是联合国教科文组织认定的世界遗产，是连绵分布的最大红树林之一。这片森林中的红树林植物的内生真菌鲜有人研究。在本研究中，我们从采集自孙德尔本斯的植物中分离出了14种内生真菌。通过宏观和微观观察，其中5种被鉴定为 属，1种被鉴定为 属。使用基于刃天青的微量滴定法测定了从这些内生真菌中获得的粗提物对 、 、 和 的抗菌活性。分离出的内生真菌表现出不同程度的抗菌活性，最低抑菌浓度（MIC）在5至0.078毫克/毫升之间。对活性最强的内生真菌进行分子鉴定，结果显示其为从 的叶片中分离得到的 。对 的乙酸乙酯提取物进行的小鼠急性毒性研究表明，即使在最高剂量2000毫克/千克体重时也未出现死亡情况，不过在亚急性毒性研究中发现了一些相反的结果。该提取物经过硅胶柱和葡聚糖凝胶柱色谱分离，得到了三种纯化合物。对这些纯化合物进行液相色谱 - 质谱分析，结果显示它们分别为烟曲霉棒曲霉素C、氮杂螺呋喃B和七叶亭。这是首次从 中报道七叶亭。此前已报道所有这三种已鉴定的化合物对不同的革兰氏阳性和革兰氏阴性细菌菌株均具有抗菌活性。因此，观察到的 的乙酸乙酯（EtOAc）提取物的抗菌活性可能归因于这些化合物的存在。这些结果支持了从孙德尔本斯研究真菌内生菌以寻找新型抗菌化合物这一观点。
