Sesquiterpene and Sorbicillinoid Glycosides from the Endophytic Fungus <i>Trichoderma longibrachiatum</i> EN-586 Derived from the Marine Red Alga <i>Laurencia obtusa</i>

Abstract

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.

Keywords

• <i>Trichoderma longibrachiatum</i>
• sesquiterpene glycoside
• secondary metabolites
• antimicrobial activity