Chemical constituents from three medicinal plants: Piper renitens, Siparuna guianensis and Alternanthera brasiliana

Chemical study of three medicinal plants: from leaves of Piper renitens (Miq.) Yunck, Piperaceae, and Siparuna guianensis Aubl., Siparunaceae, and from flowers of Alternanthera brasiliana (L.) Kuntze, Amaranthaceae, resulted in isolation of nine compounds: three steroids, beta-sitosterol, stigmasterol from P. renitens and sitosterol-3-O-beta-D-glucopyranoside from A. brasiliana, the diterpene kaurane ent-kauran-16 alpha, 17-diol from P. renitens, two derivatives kaempferol-methylether, kumatakenine (kaempferol-3,7-dimethylether) and kaempferol-3,7,3'-trimethylether from S. guianensis and three flavones, crysoeriol (5,7,4'-trihydroxy-3'-methoxyflavone), tricin (5,7,4'-trihydroxy-3', 5'-dimethoxyflavone) and 7-O-beta-D-glucopyranoside-5,4'-dihydroxy-3'-methoxyflavone from A. brasiliana. Compounds structures were determinate using 1D and 2D H-1 NMR and C-13 spectral data, mass and IR spectra, comparing with literature data.