7-O-Methylkaempferol and -quercetin Glycosides from the Whole Plant of Nervilia fordii

Five new 7-O-methylkaempferol and -quercetin glycosides, namely, nervili fordins A-E (1-5), were isolated from the whole plant of Nervilia fordii, together with seven known flavonoids (6, 7, and 9-13) and one known coumarin (8). Their structures were elucidated on the basis of extensive spectroscopic analyses, including HSQC, HMBC, ROESY, and chemical methods. Compounds 1-3 and 6-13 were evaluated for their anti-herpes simplex virus 1 (HSV-1) activity and cytotoxicity on African green monkey kidney cells (Vero cells) in vitro. Of the tested compounds, only esculetin (8) exhibited antiviral activity against HSV-1, while the aglycones (11-13) showed stronger cytotoxicity on Vero cells than their glycosides (1-3, 6, and 7).