Identification of the molecular species of acylglycerols containing hydroxy fatty acids in wild edible mushroom Ganoderma lucidum

Authors: Hou, Ching; Lin, Jiann; DULAY, RICH - Central Luzon State University; Ray, Karen

Submitted to: Biocatalysis and Agricultural Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2017
Publication Date: 7/15/2017
Citation: Hou, C.T., Lin, J.T., Dulay, R.M., Ray, K.J. 2017. Identification of the molecular species of acylglycerols containing hydroxy fatty acids in wild edible mushroom Ganoderma lucidum. Biocatalysis and Agricultural Biotechnology. 10:411-419. doi:10.1016/j.bcab.2017.05.003.

Interpretive Summary: Wild edible mushrooms are widely consumed in many countries. We successfully cultivated four edible medicinal Philippine mushrooms in liquid culture. Recently, we identified molecular species of acylglycerols in the lipid extract of the mushroom Ganoderma lucidum in the U.S. This mushroom contains 103 molecular species of acylglycerols containing all normal fatty acids (FA, fatty acids without a functional group). The chain lengths of the constituent FA were from 14-26 carbon atoms and the number of double bonds were from 0-3. There were 41 (out of 103) molecular species of acylglycerols that contained FA with odd numbered carbon atoms. In this study, we identified 72 molecular species of triacylglycerols and five molecular species of diacylglycerols containing hydroxy FA in the lipid extract of this mushroom. The high content of acylglycerols containing hydroxy FA, odd numbered carbon FA, and odd numbered carbon hydroxy FA in this edible mushroom may lead to one or more health benefits. This mushroom contains the highest amounts of hydroxy FA, odd numbered carbon FA, and odd numbered carbon hydroxy FA reported among human foods. This study will not only advance our knowledge of the lipid content of mushrooms but will also serve as a comparison to those lipids from mushrooms produced in the U.S. Studies of the oil and lipid content of agricultural materials (mushrooms) are of mutual interest to both countries.

Technical Abstract: Edible Philippine mushrooms including Ganoderma lucidum have many health benefits. Seventy-two molecular species of triacylglycerols and five molecular species of diacylglycerols containing hydroxy fatty acids (FA) in the lipid extract of this mushroom were identified by HPLC and MS. The mono-, di- and tri-hydroxy FA constituents of the molecular species of acylglycerols were identified by various degrees of dehydration of [FA + Li]+. Many odd carbon numbered hydroxy FA constituents of acylglycerols were also identified. The contents of the 77 molecular species of acylglyerols and their constituent hydroxy FA in the lipid extract were estimated by the relative ion signal intensities of the molecular species of acylglycerols and the HPLC peak area % (ELSD). The contents (%) of the molecular species of acylglycerols containing hydroxy FA in the lipid extract were as: P-19:0-2OH18:2, 0.69%; 2OH18:2-2OH18:2-2OH18:2, 0.60%; P-OH19:1-OH19:1, 0.48%; S-OH19:1-OH19:1, 0.43%; 19:0-19:0-2OH18:2, 0.27% and the total of about 5.8%. “2OH18:2” stands for dihydroxy FA with 18 carbon atoms and two double bonds. The mushroom lipid extract was 1.67% of freeze-dried mycelium. The contents (%) of individual hydroxy FA in the mushroom lipid extract in decreasing order were: 2OH18:2, 1.4%; OH19:1, 1.1%; OH18:1, 0.38%; 2OH19:0, 0.19%; 2OH18:0, 0.13% and the total of about 3.5%. The odd carbon numbered hydroxy FA was about 1.44% of the mushroom lipid extract. The high contents of acylglycerols containing hydroxy FA, odd carbon numbered FA and odd carbon numbered hydroxy FA in edible mushroom might be related to one or more of its health benefits. As far as we are aware of, this mushroom contains the highest amounts of hydroxy FA and odd carbon numbered FA among the human foods.