Stereumamides E-H, four new minor quaternary ammonium hybrids from Stereum hirsutum.

In our preview research, four novel quaternary ammonium hybrids were isolated from the Stereum hirsutum FP-91666. To further discover this type of compounds, S. hirsutum was fermented in 30 L YMG broth, and eight hybrid compounds including four new quaternary ammoniums were obtained, which are sesquiterpenes combined with α-amino acids. Their structures were elucidated by extensive spectroscopic analyses, including 1D- and 2D-NMR, and HR-MS experiments.

Four novel antibacterial sesquiterpene-α-amino acid quaternary ammonium hybrids from the mycelium of mushroom Stereum hirsutum.

The mushroom Stereum hirsutum is parasitized by Tremella aurantia to form a heterogeneous basidiocarp Jin'er, which has been used as food and folk medicine in Chinese society. In present work, the S. hirsutum was fermented in YMG broth, and four novel mixed terpenes, stereumamides A-D (1-4), which are sesquiterpenes combined with α-amino acids to form quaternary ammonium hybrids, were isolated from the Stereum hirsutum FP-91666 and their structures were elucidated by spectroscopic data analysis. Stereumamides A and D showed antibacterial activity against Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium, with the minimum inhibitory concentration (MIC) values of 12.5-25.0 µg/mL. The stereumamides A-D should be apparently the first example of naturally occurring a quaternary ammonium compound (QAC) conjugated by sesquiterpene with an α-amino acid. QAC is a common antibacterial agent in food industry, which is found in the mycelium of Stereum hirsutum would suggest that the complex basidiocarp is a functional food and veritable folk medicine.

Two new phenol derivatives from Stereum hirsutum FP-91666.

Two new phenol derivatives, 2-(3-methyl-2-buten-1-yl)-4-methoxyethyl-phenol (1) and 5-hydroxy-4-(hydroxymethyl)-2-(3-methylbut-2-en-1-yl)cyclohex-4-en-1-one (2), together with eight known compounds consisting of phenol derivatives (3 and 4), niacinamide (5), and five ergosta type compounds (6-10), were isolated from solid fermentation products of Stereum hirsutum FP-91666. Two new structures were elucidated by extensive spectroscopic methods, including 1D NMR and 2D NMR, and HR-EI-MS experiments.