World Journal of Microbiology and Biotechnology ( IF 4.0 ) Pub Date : 2021-07-07 , DOI: 10.1007/s11274-021-03099-y A Shcherbakova 1, 2, 3 , A A Strömstedt 2 , U Göransson 2 , O Gnezdilov 4 , A Turanov 4 , D Boldbaatar 2, 5 , D Kochkin 6 , G Ulrich-Merzenich 3 , A Koptina 2
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Abstract
Lichens are symbiotic organisms formed by a fungus and one or more photosynthetic partners which are usually alga or cyanobacterium. Their diverse and scarcely studied metabolites facilitate adaptability to extreme living conditions. We investigated Evernia prunastri (L.) Ach., a widely distributed lichen, for its antimicrobial and antioxidant potential. E. prunastri was sequentially extracted by hexane (Hex), dichloromethane (DCM) and acetonitrile (ACN) that were screened for their antioxidant and antimicrobial (against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans) activities. The Hex extract possessed the highest antioxidant capacity (87 mg ascorbic acid/g extract) corresponding to the highest content of phenols (73 mg gallic acid/g extract). The DCM and Hex extracts were both active against S. aureus (MICs of 4 and 21 µg/ml, respectively) but were less active against Gram-negative bacteria and yeast. The ACN extract exhibited activity on both S. aureus (MIC 14 µg/ml) and C. albicans (MIC 38 µg/ml) and was therefore further fractionated by silica gel column chromatography. The active compound of the most potent fraction was subsequently characterized by 1H and 13C-NMR spectroscopy and identified as evernic acid. Structural similarity analyses were performed between compounds from E. prunastri and known antibiotics from different classes. The structural similarity was not present. Antioxidant and antimicrobial activities of E. prunastri extracts originate from multiple chemical compounds; besides usnic acid, most notably evernic acid and derivatives thereof. Evernic acid and its derivatives represent possible candidates for a new class of antibiotics.
Graphic abstract
中文翻译：
Evernia prunastri 提取物及其分离物的抗菌和抗氧化活性
抽象的
地衣是由真菌和一个或多个光合作用伙伴（通常是藻类或蓝藻）形成的共生生物。它们多样化且很少被研究的代谢物有助于适应极端的生活条件。我们研究了Evernia prunastri (L.) Ach.（一种广泛分布的地衣）的抗菌和抗氧化潜力。依次用己烷 (Hex)、二氯甲烷 (DCM) 和乙腈 (ACN) 提取E. prunastri ，筛选其抗氧化和抗菌（针对金黄色葡萄球菌、铜绿假单胞菌、大肠杆菌和白色念珠菌）活性。六角提取物具有最高的抗氧化能力（87毫克抗坏血酸/克提取物），对应于最高的酚类含量（73毫克没食子酸/克提取物）。 DCM 和 Hex 提取物均具有对抗金黄色葡萄球菌的活性（MIC 分别为 4 和 21 µg/ml），但对抗革兰氏阴性菌和酵母的活性较低。 ACN 提取物对金黄色葡萄球菌(MIC 14 µg/ml) 和白色念珠菌(MIC 38 µg/ml) 均表现出活性，因此通过硅胶柱色谱进一步分级。随后通过1 H 和13 C-NMR 光谱对最有效部分的活性化合物进行了表征，并鉴定为醋栗酸。对E. prunastri的化合物和不同类别的已知抗生素进行了结构相似性分析。不存在结构相似性。 E. prunastri提取物的抗氧化和抗菌活性源自多种化合物；除了松萝酸之外，最著名的是醋栗酸及其衍生物。 埃维尼酸及其衍生物代表了一类新型抗生素的可能候选者。
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