Two New Fatty Acid Derivatives, Omphalotols A and B and Anti-Helicobacter pylori Fatty Acid Derivatives from Poisonous Mushroom Omphalotus japonicus.

Seulah Lee,Mi-Jeong Ahn,Yoon-Joo Ko,Yong Hoon Lee,Dong-Min Kang,Ki Hyun Kim,Rhim Ryoo,Tae Wan Kim

doi:10.3390/ph15020139

Abstract

As part of ongoing systematic research into the discovery of bioactive secondary metabolites with novel structures from Korean wild mushrooms, we investigated secondary metabolites from a poisonous mushroom, Omphalotus japonicus (Kawam.) Kirchm. & O. K. Mill. belonging to the family Marasmiaceae, which causes nausea and vomiting after consumption. The methanolic extract of O. japonicus fruiting bodies was subjected to the fractionation by solvent partition, and the CH2Cl2 fraction was analyzed for the isolation of bioactive compounds, aided by an untargeted liquid chromatography mass spectrometry (LC–MS)-based analysis. Through chemical analysis, five fatty acid derivatives (1–5), including two new fatty acid derivatives, omphalotols A and B (1 and 2), were isolated from the CH2Cl2 fraction, and the chemical structures of the new compounds were determined using 1D and 2D nuclear magnetic resonance (NMR) spectroscopy and high resolution electrospray ionization mass spectrometry (HR-ESIMS), as well as fragmentation patterns in MS/MS data and chemical reactions followed by the application of Snatzke’s method and competing enantioselective acylation (CEA). In the anti-Helicobacter pylori activity test, compound 1 showed moderate antibacterial activity against H. pylori strain 51 with 27.4% inhibition, comparable to that of quercetin as a positive control. Specifically, compound 3 exhibited the most significant antibacterial activity against H. pylori strain 51, with MIC50 and MIC90 values of 9 and 20 μM, respectively, which is stronger inhibitory activity than that of another positive control, metronidazole (MIC50 = 17 μM and MIC90 = 46 μM). These findings suggested the experimental evidence that the compound 3, an α,β-unsaturated ketone derivative, could be used as a moiety in the development of novel antibiotics against H. pylori.

Highlights

Mushrooms have been used to treat various diseases in traditional medicine [1], and a number of pharmacological and phytochemical studies on mushrooms have demonstrated that they are rich sources of various bioactive compounds that exhibit beneficial immunomodulatory, antioxidant, and angiostatic activities, as well as cytotoxicity against cancers [1,2,3,4,5]
As part of ongoing systematic research on Korean wild mushrooms for the discovery of bioactive secondary metabolites with novel structures [6], we investigated bioactive secondary metabolites from a poisonous mushroom; Omphalotus japonicus (Kawam.) Kirchm
O. japonicus is an orange-to-brown-colored gilled mushroom belonging to the family Marasmiaceae, which is found in Japan and Eastern Asia

Summary

Introduction

Mushrooms have been used to treat various diseases in traditional medicine [1], and a number of pharmacological and phytochemical studies on mushrooms have demonstrated that they are rich sources of various bioactive compounds that exhibit beneficial immunomodulatory, antioxidant, and angiostatic activities, as well as cytotoxicity against cancers [1,2,3,4,5]. Based on this evidence, mushrooms have emerged as potential valuable sources of bioactive natural products; most studies have focused on medicinal.

Methods

Results

Conclusion