title: Cyclohexadepsipeptides of the isaridin class from the marine-derived fungus Beauveria felina EN-135.
abstract: Three new cyclohexadepsipeptides of the isaridin class including isaridin G (1), desmethylisaridin G (2), and desmethylisaridin C1 (3), along with three related known metabolites (4-6), were isolated and identified from the marine bryozoan-derived fungus Beauveria felina EN-135. The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis, and the structures and absolute configurations of compounds 1-3 were confirmed by single-crystal X-ray diffraction analysis. The crystal structures showed the presence of β-turns for the Tyr(3)/N-Me-Val(4) and Phe(3)/N-Me-Val(4) amide bonds in compounds 2 and 3, respectively, in the cis conformations, which were opposite other reported isaridins. The conformations of the HMPA(1)-Pro(2) amide bond in compound 2 are different in the solution and in the crystal structures, which showed trans and cis geometries, respectively, while compounds 1 and 3 do not exhibit this phenomenon. Each of the isolated compounds was evaluated for antimicrobial activity and brine shrimp lethality. Compound 3 exhibited antibacterial activity against E. coli with an MIC value of 8 μg/mL.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences , Nanhai Road 7, Qingdao 266071, People's Republic of China.
authors.forename: Feng-Yu
authors.initials: FY
authors.lastname: Du
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Li
authors.forename: Chun-Shun
authors.initials: CS
authors.lastname: Li
authors.forename: Chuan-Ming
authors.initials: CM
authors.lastname: Cui
authors.forename: Bin-Gui
authors.initials: BG
authors.lastname: Wang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D001156:Artemia / Q000187:drug effects; D052982:Beauveria / Q000737:chemistry*; D018360:Crystallography, X-Ray; D047630:Depsipeptides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D020609:Edwardsiella tarda / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D008386:Marine Biology; D008826:Microbial Sensitivity Tests; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects; D013237:Stereoisomerism; D014733:Vibrio / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D047630:Depsipeptides; C584046:isaridin F