Sesquiterpenes with new carbon skeletons from the basidiomycete Phlebia tremellosa

Abstract

Three new sesquiterpenes, phlebidiol, phlebioic acid, and phlebiolide, as well as the known compound tremetriol, were isolated from cultures of the basidiomycete Phlebia tremellosa. The structures of all isolated compounds were established by extensive spectroscopic analyses, including those involving extensive two-dimensional nuclear magnetic resonance. The absolute configurations of phlebidiol, phlebioic acid, and phlebiolide were determined by comparisons of experimental and calculated electronic circular dichroism spectra. Phlebidiol and phlebioic acid have previously unreported carbon skeletons, for which we propose the skeletal names "seco-sterpurane" and "phlebiane," respectively. Phlebiolide is also the second published example of a merulane sesquiterpene.

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

“…Muyocopron laterale ECN279 was isolated from a healthy leaf of Canavalia lineata and identified by sequencing the D1/D2 26S rRNA gene and the internal transcript spacers (ITS) of ribosomal DNA [16]. In a similar manner as described in our previous paper [14], the whole mycelia, which were cultured on 2% malt extract agar, were extracted with methanol (MeOH) at room temperature and the extracted solution was evaporated to obtain the crude extract. The crude extract was then partitioned between ethyl acetate and water, and muyocopronones A (1) and B (2) were isolated from the ethyl acetate layer together with eugenitin (3) [17], and 6-methoxymethyleugenin (4) [18].…”

“…Calculation of the ECD spectra were performed using CONFLEX 8, Gaussian 16, and SpecDis software as described previously [13,14]. Geometry optimizations were performed using DFT at the CAM-B3LYP/6-311+G(d,p) level of theory, while TDDFT calculations were conducted at the B3LYP/6-311+G(d,p) level of theory.…”

“…However, little information exists regarding the fungal metabolites produced by Muyocopron spp. Thus, as part of our research into the natural products produced by plant-associated fungi [13][14][15], we isolated two new azaphilones from the cultures of an endophytic fungus, namely Muyocopron laterale ECN279. Herein, the isolation, structural elucidation, and antimicrobial activity evaluation are described.…”

Absolute configurations of talaromycones A and B, α-diversonolic ester, and aspergillusone B from endophytic Talaromyces sp. ECN211

“…The methods of fermentation and extraction of the fungus Talaromyces sp. ECN211 were performed in a similar manner as described previously [9].…”

“…Therefore, the reported absolute configurations of 3 and aspergillusone B (4) lack the evidence that supports their assignments, i.e., the absolute configurations of α-diversonolic ester (3), aspergillusone B (4), and their related compounds are still unknown. As part of our research into compounds produced by endophytic fungi in Japan [7][8][9], we isolated two new diversonolic ester-related xanthenediones from Talaromyces sp. ECN211, namely talaromycones A (1) and B (2), as well as α-diversonolic ester (3) [5], and aspergillusone B (4) [6].…”