Cyclooxygenase Inhibitory and Antioxidant Compounds from the Mycelia of the Edible Mushroom Grifola frondosa

The bioassay-guided isolation and purification of the hexane extract of the cultured mycelia of Grifola frondosa led to the characterization of a fatty acid fraction and three compounds, ergosterol (1), ergostra-4,6,8(14),22-tetraen-3-one (2), and 1-oleoyl-2-linoleoyl-3-palmitoylglycerol (3). The composition of fatty acid fraction was confirmed as palmitic, oleic, and linoleic acids by GC-MS and by comparison with the retention values of authentic samples. The structures of compounds 1−3 were established by spectroscopic methods. The fatty acid fraction and compounds 1−3 showed cyclooxygenase (COX) enzyme inhibitory and antioxidant activities. The inhibition of COX-1 enzyme by the fatty acid fraction and compounds 1−3 at 250 μg/mL were 98, 37, 55, and 67%, respectively. Similarly, COX-2 enzyme activity was reduced by fatty acid fraction and compounds 1−3 at 250 μg/mL by 99, 37, 70, and 4%, respectively. The inhibitions of liposome peroxidation by the fatty acid fraction and compounds 1 and 2 at 100 μg/mL were 79, 48, and 42%, respectively. This is the first report of compounds 2 and 3 from the cultured mycelia of G. frondosa. The COX inhibitory activities of compounds 1−3 are reported here for the first time. Keywords: Grifola frondosa; mycelia; fatty acid; palmitic acid; oleic acid; linoleic acid; ergosterol; ergostra-4,6,8(14),22-tetraen-3-one; 1-oleoyl-2-linoleoyl-3-palmitoylglycerol