Sesquiterpenoids and their quaternary ammonium hybrids from the mycelium of mushroom Stereum hirsutum by medium optimization

• Published in: Phytochemistry (Oxford) 2021-09, Vol.189, p.112852-112852, Article 112852
• Main Authors: Pu, Xue-Juan, Hu, Qian-Yi, Li, Su-Su, Li, Guo-Hong, Zhao, Pei-Ji
• Format: Article
• Language: English
• Subjects: Antibacterial activity; Quaternary ammonium hybrids; Sesquiterpene; Stereaceae; Stereum hirsutum
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2021.112852

The fungal genus Stereum (Stereaceae) produces a broad variety of specialised metabolites, including a wide range of terpenes. This probably relates to the presence of an extensive biosynthetic machinery for this group of compounds: genomic analysis of Stereum hirsutum has identified 16 terpene synthase gene clusters, 6 polyketide synthase gene clusters, and 1 polyketide synthase non-ribosomal polypeptide heterodimer gene cluster in S. hirsutum FP-91666. In the present study, the One Strain Many Compounds (OSMAC) approach was employed to discover undescribed metabolites from this strain. Fermentation was carried out in five media and the products of the strain cultivated on different media were analyzed by LC-MS. From cultures grow in WGB medium (30.0 g wheat bran, 20.0 g glucose, 1.5 g KH2PO4, and 1.5 g MgSO4), four previously undescribed metabolites, a sesquiterpene sterostrein X and three mixed terpenes (stereumamides I–K) were isolated, together with seven known compounds (drimene-2,11-diol, stereumamide E, stereumamide D, stereumamide B, stereumamide A, stereumamide C, and sterostrein Q). The drimane-type sesquiterpene drimene-2,11-diol was found in S. hirsutum FP-91666 for the first time. All structures were elucidated by spectroscopic data analysis. The absolute configurations of stereumamides I, J and K were assigned by comparing their experimental and calculated electronic circular dichroism (ECD) spectra. An anti-Mycobacterium tuberculosis experiment showed that stereumamides I–K and sterostrein Q had weak antibacterial activity against this pathogen. [Display omitted] •OSMAC approach was employed to discover undescribed metabolites from Stereum hirsutum.•WGB medium was selected to culture the strain based on the analysis of LC-MS.•Four undescribed metabolites were isolated from the fermentation extracts.•The drimane type sesquiterpene drimene-2,11-diol was isolated from the strain for the first time.•Stereumamides I–K and sterostrein Q had weak anti-Mycobacterium tuberculosis activity.