potential of syntheticisoflavones for application in cosmeceuticals. Twenty‐five isoflavones were synthesized and their capacities of free‐radical‐scavenging and mushroom tyrosinase inhibition, as well as their impact on cell viability of B16F10 murine melanoma cells and HaCaT human keratinocytes were evaluated. Isoflavones that showed significant mushroom tyrosinase inhibitoryactivities were further
Synthesis of isoflavones via base catalysed condensation reaction of deoxybenzoin
作者:Wanmei Li、Fangming Liu、Pengfei Zhang
DOI:10.3184/030823408x382135
日期:2008.12
Basecatalysedcondensation reaction of o-hydroxyl-α-phenylacetophenones with formyl reagents affords various substituted isoflavones. Many bases were tested in the condensation reaction and DMAP was found to be the most effective catalysis.
O-methylation of flavonoids by cell-free extracts of calamondin orange
作者:Gunter Brunet、Ragai K. Ibrahim
DOI:10.1016/0031-9422(80)85102-8
日期:——
hydroxyls of a number of flavonoids, indicating the existence in citrus tissues of ortho, meta, para and 3-O-methyltransferases. The latter, hitherto unreported enzyme, catalysed the formation of 3-O-methylethers of galangin and quercetin. The stepwise O-methylation of a number of compounds, especially quercetin and quercetagetin, tends to suggest a coordinated sequence of O-methylations on the surface
Synthesis of Various Kinds of Isoflavones, Isoflavanes, and Biphenyl-Ketones and Their 1,1-Diphenyl-2-picrylhydrazyl Radical-Scavenging Activities
作者:Hideyuki Goto、Yoshiyasu Terao、Shuji Akai
DOI:10.1248/cpb.57.346
日期:——
Forty-eight kinds of isoflavones (8), thirty-one isoflavanes (9), and forty-seven biphenyl-ketones (10, 10′) were synthesized from eleven kinds of substituted phenols (11) and six phenylacetic acids (12). Among them, seventy-five compounds are new. The radical scavenging activities of these compounds were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) at pH 6.0. We found that thirty-nine out of forty-three compounds having a catechol moiety on either the A- or the B-ring exhibited a high activity (ED50=12—54 μM) similar to that of catechin. In these cases, the remaining part of their structure seemed to have little effect on their activity. Many 6- or 8-hydroxyisoflavanes (9E—I) and their biphenyl-ketone derivatives (10E—H) also showed a high activity (ED50=<50 μM), while all of their corresponding isoflavones (8E—I) were not active at all. The 7-hydroxyisoflavanes having either an additional hydroxyl group at the C5-position (9D) or a methoxy group at the C6-position (9J) presented a high activity (ED50=26—32 μM). This study suggests that natural isoflavones have the possibilities of exhibiting antioxidant activities through the hydroxylation at the C6-, C8-, or C3′-position or the formation of the isoflavanes (9) and/or the biphenyl-ketone derivatives (10′) by metabolism or biotransformation.