- Dietary phytoestrogens and their synthetic structural analogues as calcium channel blockers in human platelets.
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Phytoestrogens have been shown to inhibit platelet activation by blocking platelet calcium channels. This study examined the effect of several synthetic derivatives of trans-resveratrol, genistein, and daidzein on platelet free intracellular calcium ([Ca2+]i) elevation in thrombin-activated platelets and the possible mechanisms of this inhibitory effect. Studies were conducted on fresh human platelets from healthy volunteers. The fluorescent dye fura-2 was used to monitor [Ca2+]i in platelets. At 10 microM-resveratrol, triacetyl-trans-resveratrol, and trimethoxy-trans-resveratrol produced, respectively, 57 +/- 4%, 40 +/- 4%, and 21 +/- 1% inhibition; genistein, acetylgenistein, and dihydrogenistein produced 51 +/- 10%, 26 +/- 7%, and 16 +/- 2% inhibition, respectively; daidzein and diacetyldaidzein produced 56 +/- 5% and 45 +/- 10% inhibition of thrombin-induced [Ca2+]i elevation. The inhibitory effect was immediate and appeared to directly affect the calcium influx channels. Phytoestrogen action on [Ca2+]i did not cause alteration in nitric oxide signaling. Tyrosine phosphorylation was not involved in the inhibition of [Ca2+]i elevation by phytoestrogens, because the percent inhibition produced by the tyrosine kinase inhibitor genistein and its inactive analogue daidzein on thrombin-induced and thapsigargin-induced [Ca2+]i elevation was not significantly different for either compound at any concentration tested. Structure-activity relationship studies on this limited set of compounds reveal the requirements for the stilbene pharmacophore for the calcium-blocking activity.
- Dobrydneva, Yuliya,Williams, Roy L,Morris, Gary Z,Blackmore, Peter F
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- Therapeutic methods and compositions involving isoflavones
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Therapeutic methods of treatment, compositions and foodstuffs are described which contain isoflavone compounds described by general formula (1), in which Z is H, R1 is H, or RACO where RA is C1-10alkyl or an amino acid, R2 is H, OH, or ORB where RB is an amino acid, or CORA where RA is as previously defined, W is H, A is H or OH, and B is selected from (a), (b), (c), or W is H, and A and B taken together form a six-membered ring selected from (d), or W, A and B taken with the groups with which they are associated comprise (e), or W and A taken together with the groups with which they are associated comprise (f) and B is (g) wherein R3 is H, CORA where RA is as previously defined, CO2Rc where RC is C1-10alkyl, or CORB where RB is as previously defined, R4 is H, CORD where RD is H, OH, C1-10alkyl or an amino acid, CO2RC where RC is as previously defined, CORE where RE is H, C1-10alkyl or an amino acid, COOH, CORC where RC is as previously defined, or CONHRE where RE is as previously defined, R5 is H, CORC where RC is as previously defined, or CORCORE where RC and RE are as previously defined, and where the two R5 groups are attached to the same group they are the same or different, R6 is H or hydroxy C1-10alkyl, X is preferably O, but may be N or S, and Y is (h) where R7 is H, or C1-10alkyl.
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- Isoflavanones from the heartwood of Swartzia polyphylla and their antibacterial activity against cariogenic bacteria
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The methanolic extract of Swartzia polyphylla DC. heartwood had antibacterial activity against cariogenic bacteria, the mutans Streptococci. The chromatographic purification of the extract afforded seven flavonoids. Among them, three known isoflavanones, dihydrobiochanin A, ferreirin and darbergioidin, and one new isoflavanone, 5,2',4'-trihydroxy-7-methoxyisoflavanone (dihydrocajanin) had potent antibacterial activity against cariogenic bacteria. This effect was not detected on isoflavone derivatives. A comparative antibacterial study of various flavonoids was further performed, and their structure-activity relationship was discussed.
- Osawa,Yasuda,Maruyama,Morita,Takeya,Itokawa
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p. 2970 - 2974
(2007/10/02)
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- HYDROGEN TRANSFER REDUCTION OF ISOFLAVONES
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Hydrogen transfer reduction of isoflavones using ammonium formate and palladium charcoal provides an easy access to polyoxyisoflavanones and also to isoflavan-4-ols without the need for protection of the hydroxy groups.Optimized reaction conditions for im
- Waehaelae, K.,Hase, T. A.
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p. 183 - 186
(2007/10/02)
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- NADPH: BIOCHANIN A OXIDOREDUCTASE FROM THE FUNGUS FUSARIUM JAVANICUM
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A soluble enzyme which catalyses the NADPH-dependent reduction of the heterocyclic double bond of the isoflavone biochanin A (5,7-dihydroxy-4'-methoxy-isoflavone) yielding the corresponding isoflavanone was isolated from the fungus Fusarium javanicum.The NADPH: biochanin A oxidoreductase was constitutively present in the mycelium with an extractable average activity of 4 pkat/g fresh weight.The enzyme was purified ca 4500 fold to apparent homogeneity.The native enzyme had Mr of ca 87000 and consisted of two identical subunits of Mr 43000.The enzyme reaction showed a pH-optimum at pH 7.5 and a temperature optimum between 30 and 35 deg.The apparent Km values were 43 μM for biochanin A and 190 μM for NADPH with a maximum velocity of 4 mkat/kg protein.The enzyme exhibited a remarkable substrate specificity for biochanin A. - Key Word Index: Fusarium javanicum; Hyphomycetes; NADPH: biochanin A oxidoreductase; isoflvone metabolism; biochanin A.
- Schlieper, Dittmar,Barz, Wolfgang
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p. 2495 - 2498
(2007/10/02)
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