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

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.