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Uncommon N ‐Methoxyindolediketopiperazines from Acrostalagmus luteoalbus , a Marine Algal Isolate of Endophytic Fungus
Author(s) -
Cao Jin,
Li XiaoMing,
Li Xin,
Li HongLei,
Konuklugil Belma,
Wang BinGui
Publication year - 2021
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.202100368
Subject(s) - chemistry , stereochemistry , marine fungi , antimicrobial , fungus , absolute configuration , edwardsiella tarda , pathogenic bacteria , antibacterial activity , acetylcholinesterase , bacteria , two dimensional nuclear magnetic resonance spectroscopy , enzyme , botany , biochemistry , organic chemistry , biology , genetics , gene
Main observation and conclusion Four new N‐ methoxyindolediketopiperazines (acrozines D—G, 1—4) and six known congeners (5—10) were purified from the organic extract of Acrostalagmus luteoalbus TK‐43, which was a marine algal‐derived fungus obtained from Codium fragile . Their structures were determined by interpretation of NMR and mass spectroscopic data. The structures of compounds 1, 2, and 4 including their absolute configurations were confirmed by single‐crystal X‐ray diffraction, while the absolute configuration of compound 3 was elucidated by comparative analysis of ECD and TDDFT‐ECD calculations. Compounds 1—4, with a unique methoxy substitution at N ‐2, were rarely discovered among indolediketopiperazine alkaloids. All these compounds were evaluated for antimicrobial activities against human‐ and aquatic‐pathogenic bacteria and plant‐related pathogenic fungi, with compounds 5 and 7 exhibiting potent activity against Edwardsiella icataluri (MIC = 3 and 5 μmol/L, respectively), while compound 9 displayed a broad spectrum of antibacterial activities. The four new compounds were further tested for anti‐acetylcholinesterase (AChE) properties, and compound 3 exhibited inhibitory activity with IC 50 value of 8.4 μmol/L.