Naphthopyranone glycosides from Paepalanthus microphyllus.

Three new naphthopyranone glycosides, paepalantine-9-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (1), paepalantine-9-O-α-l-arabinopyranosyl-(1→6)-β-d-glucopyranoside (2), and paepalantine-9-O-α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside (3), along with the known paepalantine-9-O-β-d-glucopyranoside (4) were isolated from aerial parts of Paepalanthus microphyllus. These compounds were characterized by spectrometric methods, including electrospray mass spectrometry and 1D and 2D NMR experiments. As a part of our program for screening natural compounds for anti-HIV activity, compounds 1−4 were tested in C8166 cells infected with HIV-1MN.