Conjugated Ketonic Fatty Acids from Pleurocybella porrigens

Abstract

The fungus Pleurocybella porrigens (Japanese name: Sugihiratake), a basidiomycete of the Tricholomataceae family, is a small, flat, white mushroom. This edible mushroom grows during the late summer and autumn and is native to all districts of Japan including the Tohoku and Hokuriku areas. In the autumn of 2004, several perplexing acute encephalopathy cases were diagnosed in the Tohoku and Hokuriku areas, and the intake of this mushroom was identified as one of the common factors in these cases.2-6) As a first step to clarify the relationship between the acute encephalopathy cases and this mushroom, we conducted an investigation to determine the chemical constituents of P. porrigens. 7) In the course of this work, we isolated and characterized three novel conjugated long-chain fatty acids (compounds 1-3) together with nine known compounds [(8E,10E)-7,12-dioxo-8,10-octadecadienoic acid (ostopanic acid) (4), 8,9) tryptophan, adenine, trans-cinnamic acid, ergosterol, 10) triolein, 11) a-and beleostearic acids, 12,13) and methyl a-eleostearate 14) ] from aqueous methanol extract of P. porrigens. This paper deals with the structural elucidation of these new compounds based on spectroscopic methods. Results and DiscussionA 50% aqueous methanol extract of P. porrigens was fractionated by chromatography on Diaion HP-20 with aqueous MeOH, then each fraction showing similar patterns on HPLC or TLC was combined. Further purification was performed by a combination of chromatography over MCI-gel CHP 20P with a step-wise gradient elution using aqueous MeOH, preparative HPLC, and preparative TLC to afford three novel compounds (1-3) along with nine known constituents.Compound 1 These spectral features along with four unsaturation degrees in the molecular formula and UV data suggested 1 to be a C18 unsaturated oxo fatty acid with linear structure. The 1 H-13 C heteronuclear multiple-bond connectivity (HMBC) spectrum showed long-range correlations as follows: H-2 and C-1, 3, 4; H-8 and C-6, 7, 9; H-10 and C-9, 12; H-11 and C-9, 10, 13; H-12 and C-11, 14; H-13 and C-11, 14; H-14 and C-12; H-15 and C-13, 14, 16, 17; and H-18 and C-16, 17, indicating the locations of a carbonyl carbon at C-9 and a tertiary carbon at C-14. Although the proposed structure (1) has an asymmetric carbon at C-14, 1 was regarded as a racemate Three novel conjugated long-chain fatty acids (1-3) were obtained from aqueous methanol extracts of Pleurocybella porrigens together with nine known constituents including (8E,10E)-7,12-dioxo-8,10-octadecadienoic acid (ostopanic acid) (4). The structures of the new fatty acids were characterized as (14RS)-(10E,12E)-14-hydroxy-9-oxo-10,12-octadecadienoic acid (1), (12RS)-(8E,10E)-12-hydroxy-7-oxo-8,10-octadecadienoic acid (2), and (10E,12E)-9,14-dioxo-10,12-octadecadienoic acid (3) by spectroscopic methods.

New Octadecanoid Enantiomers from the Whole Plants of Plantago depressa

“…The 13 C NMR data ( Table 2 ) showed signals of a conjugated ketone ( δ C 203.7, C-9), an ester carbonyl ( δ C 176.0, C-1), four olefinic ( δ C 128.8, 130.3, 144.3, 148.5; C-10 to C-13), an oxygenated methine ( δ C 72.6, C-14), a methoxy ( δ C 52.0), ten aliphatic methylene ( δ C 23.7, 25.5, 26.0, 28.7, 30.0, 30.1, 30.2, 37.8, 34.8, 41.0), and a methyl ( δ C 14.4, C-18) carbon. These spectral features were similar to those of compound 10 isolated from the fungus Pleurocybella porrigens [ 11 ] but with an additional methoxy group, suggestive of a methyl ester derivative. Detailed examination of 2D 1 H- 1 H COSY (correlated spectroscopy) and HMBC (heteronuclear multiple-bond correlation) data ( Figure 2 ) confirmed the above conclusion with key HMBC correlations from H 2 -7, H 2 -8, H-10 and H-11 to C-9 ( δ C 203.7), and H 2 -2, H 2 -3 and OC H 3 to C-1 ( δ C 176.0,).…”

Eleostearic acid induces RIP1-mediated atypical apoptosis in a kinase-independent manner via ERK phosphorylation, ROS generation and mitochondrial dysfunction

“…We isolated several fatty acids that exert cell cytotoxicity as well as ESA. 31, 32 The relationship between cytotoxic fatty acids and acute encephalopathy caused by ESA remains to be solved. As previously reported, 27 as low as 2  μ g/ml ESA induces atypical apoptotic cell death, which is blocked by α -tocopherol (Toc), the MEK inhibitor U0126 and MEK1/2 knockdown.…”

A-WINGS: an integrated genome database for Pleurocybella porrigens (Angel’s wing oyster mushroom, Sugihiratake)

“…Unexpectedly, in 2004, a total of 55 cases of food poisoning were reported due to consumption of the mushroom, with 17 of them ending in death due to acute encephalopathy. Despite an aggressive effort to identify the underlying cause of these events [ 3 – 11 ], the molecular basis remains obscure.…”