Naphthopyranone glycosides from Paepalanthus microphyllus

Three new naphthopyranone glycosides, paepalantine-9-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (1), paepalantine-9-O-alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranoside (2), and paepalantine-9-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (3), along with the known paepalantine-9-O-beta-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.