Flavonoids from Gutierrezia Repens (Asteraceae)

7,3'-dimethylquercetin 1, 7,3,3'-trimethylquercetin 2, 7,3,4'-trimethylquercetin 3 and quercetin 4 were isolated from aerial parts of gutierrezia repens (asteraceae). the structures of 1, 2 and 3 were determined mainly on the basis of 2d nmr data. their 1h nmr spectra in cdcl3 and me2co-d6 are compared and discussed. the 13c nmr spectra of these compounds are given here for the first time.