Methylated flavonols in Larrea cuneifolia

摘要: Abstract Nine of eleven methylated flavonols isolated from Larrea cuneifolia Cav. collected in Argentina have been fully characterized. UV, MS and NMR spectral data are presented for the nine substances all which were identified as methyl ethers quercetin kaempferol. Two compounds, 7,3′,4′-trimethylquercetin (II) 3,7,3′-trimethylquercetin (III), new natural products. The others 3,7,3′,4′-tetramethylquercetin (I) (retusine), 3,7-dimethylkaempferol (IV), 7,3′-dimethylquercetin (V) (rhamnazin), 3,7-dimethylquercetin (VI) (kumatakenin), 3,3′-dimethylquercetin (VII), 3-methylkaempferol (VIII) 3′-methylquercetin (IX) (isorhamnetin). Nordihydroguaiaretic acid (XII) was also detected.