Fungal β-Glycosidase Belonging to Subfamily 4 of Glycoside Hydrolase Family 30 with Transglycosylation Activity

Fomitopsis palustris, a prominent wood decayer, is known to produce a variety of glycoside hydrolases (GHs). In this study, we characterized a fungal β-glycosidase belonging to subfamily 4 of GH family 30 (GH30). The recombinant protein (FpGH30) showed the highest hydrolytic activity toward p-nitrophenyl-β-d-fucopyranoside (pNPβFuc), followed by p-nitrophenyl-α-l-arabinopyranoside (pNPαAra) and p-nitrophenyl-β-d-galactopyranoside (pNPβGal). FpGH30 also exhibited transglycosylation activities, which catalyzed the transfer of glycosyl moieties to different glycosides and alkyl alcohols. When pNPβFuc, pNPβGal, and pNPαAra were used as substrates, self-condensation reactions occurred, leading to the production of the corresponding transglycosylated products with yields of 21, 26, and 25%, respectively. The enzyme was also able to catalyze the transfucosylation of pNP derivatives of β-d-glucose, β-d-mannose, and β-d-xylose and alkyl alcohols (C1-C6), producing the corresponding transfucosylated products and alkyl fucosides. Our study indicates that FpGH30 is the first characterized fungal β-glycosidase belonging to subfamily 4 of GH30 with transglycosylation activities.

Lanostane-type C31 triterpenoid derivatives from the fruiting bodies of cultivated Fomitopsis palustris

Fifteen undescribed and five known lanostane-type C₃₁ triterpenoid derivatives were isolated from the aqueous EtOH extract of the fruiting bodies of cultivated Fomitopsis palustris. Their structures were identified from the spectroscopic data and chemical degradation studies. The structures of palustrisoic acids A and H were confirmed by X-ray crystallography. Polyporenic acid B showed strong cytotoxicity against the HCT116, A549, and HepG2 cell lines with IC₅₀ values of 8.4, 12.1, and 12.2 μM, respectively. Palustrisolides A, C, and G displayed weak cytotoxicity.