Two new peroxy fatty acids with antibacterial activity from Ophioglossum thermale Kom.

Two new peroxy fatty acids, thermalic acids A (1) and B (2), together with eight known compounds, (3ß)-methyl-3-hydroxy-urs-11-en-28 oate (3), luteolin (4), quercetin (5), 3-methoxyquercetin (6), ophioglonol (7), ophioglonol 4'-O-α-D-glucopyranoside (8), pedunculosumoside B (9), syringol (10), were isolated from the herba of Ophioglossum thermale Kom. The structures of 1 and 2 were identified by HRESIMS, EIMS, 1D and 2D NMR, and electronic circular dichroism (ECD) spectra. Both two acids exhibited potential antibacterial activities against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli. This is the first report of peroxy fatty acids isolated from herbaceous plants of Ophioglossaceae.