Trichocadinins B–G (1–6), six new cadinane-type sesquiterpene derivatives, each with C-14 carboxyl functionality, were isolated from the culture extract of Trichoderma virens QA-8, an endophytic fungus obtained from the fresh inner tissue of the medicinal plant Artemisia argyi. Their structures were elucidated by interpretation of the NMR spectroscopic and mass spectrometric data. The structures and absolute configurations of compounds 1 and 3 were confirmed by X-ray crystallographic analysis. Compounds 1–3 showed antibacterial and antifungal activity.

Five new polyhydroxylated hydroanthraquinone derivatives, namely, 8-hydroxyconiothyrinone B (1), 8,11-dihydroxyconiothyrinone B (2), 4R,8-dihydroxyconiothyrinone B (3), 4S,8-dihydroxyconiothyrinone B (4), and 4S,8-dihydroxy-10-O-methyldendryol E (5), were isolated and identified from the culture extract of Talaromyces islandicus EN-501, an endophytic fungus obtained from the inner tissue of the marine red alga Laurencia okamurai. The structures of these compounds were established on the basis of detailed interpretation of their NMR and mass spectroscopic data, and the structures and absolute configurations of compounds 1 and 2 were confirmed by X-ray crystallographic analysis, while the absolute configurations of compounds 3-5 were determined by TDDFT calculations of the ECD spectra. The antimicrobial, antioxidant, and cytotoxic activities of compounds 1-5 were evaluated.

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 IC50 value of 8.4 μmol/L.

An unusual sesquiterpene glycoside trichoacorside A (1) and two novel sorbicillinoid glycosides sorbicillisides A (2) and B (3), together with a known compound sorbicillin (4), were isolated and identified from the culture extract of an endophytic fungus Trichoderma longibrachiatum EN-586, obtained from the marine red alga Laurencia obtusa. Trichoacorside A (1) is the first representative of a glucosamine-coupled acorane-type sesquiterpenoid. Their structures were elucidated based on detailed interpretation of NMR and mass spectroscopic data. The absolute configurations were determined by X-ray crystallographic analysis, chemical derivatization, and DP4+ probability analysis. The antimicrobial activities of compounds 1–4 against several human, aquatic, and plant pathogens were evaluated.