- Synthesis and structure-activity relationship study of deoxybenzoins on relaxing effects of porcine coronary artery
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Deoxybenzoins are potent antioxidants and tyrosinase inhibitors with potential to be developed as food preservatives and cosmetic ingredients. To explore the potential in cardiovascular protection, 25 polyphenolic deoxybenzoins were synthesized and evaluated for inhibitory effects on KCl-induced porcine coronary arterial contraction. The results revealed deoxybenzoins are significant inhibitors of KCl-induced arterial contraction. Among those synthesized, two-thirds of the deoxybenzoins exhibited moderate to good efficacy on relaxing contracted artery including 2,4-dihydroxydeoxybenzoin with EC50 = 3.30 μM (Emax = 100%, n = 7) and 2,4-dihydroxy-4′-methoxydeoxybenzoin EC50 = 3.70 μM (E max = 100%, n = 5). Deoxybenzoins displayed an endothelium-dependent relaxing manner on the contracted artery; the contractile responses of neither endothelium denuded nor L-NAME deactivated rings were inhibited. The structure-activity relationships of deoxybenzoin on arterial relaxing effects concluded that the 2,4-dihydroxylated deoxybenzoins presented a potential vascular relaxing pharmacophore, with favoring substitution on ring B in the order of H ≤ p-OMe > p-OH > o-OMe > m,p-diOMe ≤ m-OMe.
- Lu, Tzy-Ming,Kuo, Daih-Huang,Ko, Horng-Huey,Ng, Lean-Teik
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experimental part
p. 10027 - 10032
(2011/05/17)
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- Potential antioxidants and tyrosinase inhibitors from synthetic polyphenolic deoxybenzoins
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Deoxybenzoins (DOBs) are one-pot synthetic precursors of isoflavones with feature analogous to those beneficial polyphenols such as resveratrol (stilbene) and phloretin (dihydrochalcone). In this study, seventeen polyphenolic DOBs were synthesized and evaluated by various antioxidant assays and tyrosinase inhibitory effect in vitro. Results displayed that these DOBs are powerful antioxidants; for example, 2,3,4-trihydroxy-3′,4′-dimethoxydeoxybenzoin possesses an excellent anti-lipid peroxidation activity (IC50 = 0.72 ± 0.16 μM), whilst 2,4,4′,5-tetrahydroxydeoxybenzoin showed good DPPH radical scavenging activity (IC50 = 0.69 ± 0.04 μM), which were better than Trolox and vitamin C. Besides exhibiting a weak metal chelating effect, these DOBs were effective in scavenging ABTS{radical dot}+ and superoxide anion (O2{radical dot} -) radicals. DOBs also exhibited potent mushroom tyrosinase inhibitory activity; for example 2,3,4′-trihydroxy-4-methoxydeoxybenzoin displayed stable and significant inhibitory effect on tyrosinase activity, with IC50 values 43.37, 43.10 and 46.10 μM at incubation intervals of 0.5, 1.5, and 2.5 h, respectively. These results suggest that, with the advantage of being readily synthesizable small molecules, DOBs can be potentially developed into clinical and industrial antioxidants. Crown Copyright
- Ng, Lean-Teik,Ko, Horng-Huey,Lu, Tzy-Ming
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experimental part
p. 4360 - 4366
(2009/10/17)
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- Synthesis of various kinds of isoflavones, isoflavanes, and biphenyl- ketones and their 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activities
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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=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.
- Goto, Hideyuki,Terao, Yoshiyasu,Akai, Shuji
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experimental part
p. 346 - 360
(2009/12/27)
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