Structure-function analysis of the radioprotective and antioxidant activity of flavonoids

The recombination kinetics of a series of flavonoids with stable DPPH radicals are studied. Flavonols are the most reactive. Polarization of the carbonyl in flavones reduces the reactivity. Substitution on C-7 and the B ring has practically no effect on the reactivity. Glycosylation of C-3 reduces the reactivity if the sugar can form two intramolecular H-bonds. The reactivity of the flavonoid phenol hydroxyls, with the exception of the hydroxyl on C-5, is proportional to their number. The most promising antioxidants are lespedin, kaempferitrin, kaempferol, kaempferol-7-rhamnoside, kaempferol-3-robinobioside, and robinin.I. G. Kutateladze Institute of Pharmacochemistry, Georgian Academy of Sciences, Tbilisi, fax (99532)-25-00-26. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 42–46, January–February, 2000.     

类黄酮抑制 IP6Ks 的3D-QSAR 研究

采用基于R基团搜索技术的Topomer CoMFA建立了14个类黄酮类肌醇六磷酸激酶抑制剂的3D-QSAR模型,研究了类黄酮化合物对肌醇六磷酸激酶(IP6Ks)活性的抑制作用.该模型的主成分数为3,拟合与留一法交互验证的复相关系数以及F检验值分别为q²=0.842,q_st²=0.26;r²=0.965,r_st²=0.12;F=91.519.在此基础上通过Topomer Search进行分子片段筛选,对化合物8,14和6进行重新拼接设计,其预测活性可以分别提高12.76倍、9.27倍和62%.运用Surflex-dock分子对接法研究了实验数据中活性最高的化合物6和活性最低的化合物10与IP6Ks的PDB结构的作用机制,发现并验证了之前所建立的Topomer CoMFA模型构效关系分析研究的结果,进一步阐明了化合物6抑制活性更高的原因.结果表明,在类黄酮分子结构的C(5),C(7)和C(4′)位上,取代基团的大小和静电性质对其抑制活性产生重要的影响.本研究可...     

Study of the inhibiting activity of tocopherol

Conclusions Tocopherol possesses a high ability to react with peroxide radicals; the stoichiometric coefficient of inhibition is equal to 3.2. The conversion products of tocopherol also possess inhibiting properties; however, their activity is approximately 20 times lower than the activity of free tocopherol.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2714–2718, December, 1972.     

Antimutagenic activity of flavonoids from Sozuku

Pinocembrin (1) and cardamonin (2) from Sozuku showed a suppressive effect on umu gene expression of SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen furylfuramide. Compounds 1 and 2 suppressed 52% and 36% of SOS-inducing activity at a concentration of 0.20 μmol/mL. The ID₅₀ value of 1 was 0.18 μmol/mL. These compounds showed the suppression of 2-amino-3,4-dimethylimidazo-[4,5-f]quinolone (MeIQ) and UV irradiation-induced SOS response. Pinostrobin (3) and 5,7-dimethoxyflavanone (4), methyl ethers of 1, showed similar activity to 1 against MeIQ-induced SOS response, but that of furylfuramide and UV irradiation were decreased. On the other hand, compounds 1–4 did not show the suppression of activated MeIQ-induced SOS response. Furthermore, compounds 1–4 showed potent antimutagenic activity against MeIQ mutagenesis in Ames test using the S. typhimurium TA100 and TA98 strains.     

Inhibition of adenosine 3',5'-cyclic monophosphate phosphodiesterase by flavonoids. III

Sixty-one flavanones, twenty-six isoflavones and eight other flavonoids, obtained from Sophora tomentosa, S. flavescens, Scutellaria baicalensis and other medicinal plants or synthesized, were tested for their inhibitory activity against adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase from beef heart. The structure-activity relationships were investigated.     

Synthesis and immunosuppressive activity of L-rhamnopyranosyl flavonoids

Astilbin, a flavonoid isolated from different plants, shows diverse biological activities. This paper reports the synthesis and immunosuppressive activity of seven analogues of astilbin, which may shed light on the structure-activity relationship of the compounds. The following glycosyl flavonoids, 6-alpha-L-rhamnopyranosyloxyflavanone (20), 3-alpha-L-rhamnopyranosyloxyflavone (22), 3-alpha-L-rhamnopyranosyloxyflavanone (24), 3-alpha-L-rhamnopyranosyloxychromanone (26), 4-alpha-L-rhamnopyranosyloxychromanol (27), 7-hydroxy-3-alpha-L-rhamnopyranosyloxyflavanone (30) and 4'-hydroxy-3-alpha-L-rhamnopyranosyloxyflavanone (32) were prepared respectively by glycosylation of 6-hydroxyflavanone (1), 3-hydroxyflavone (2), 3-hydroxyflavanone (5), 3-hydroxychromanone (8), 4-chromanol (9), 7-benzyloxy-3-hydroxyflavanone (12), 4'-benzyloxy-3-hydroxyflavanone (15). Among them, compounds 5, 8, 12 and 15 were synthesized from flavanone (3), 4-chromanone (6), 7-hydroxyflavanone (10) and 4'-hydroxyflavanone (13) respectively. Similar to astilbin (4), compounds 22, 24, 26, 30 and 32 significantly inhibited the single mixed lymphocytes reaction (sMLR) and enhanced the apoptosis of spleen cells isolated from mice with sheep red blood cell-induced delayed-type hypersensitivity respectively. However, compound 20 only showed a slight tendency to inhibit sMLR at higher concentration. Both compounds 20 and 27 did not influence the cell apoptosis. These data suggest that the following factors play essential roles in determining the biological activity of the flavonoids: the position at which the sugar is linked to the flavone, the presence of carbonyl on C-4 and phenol hydroxyl group in A or B ring. However, the presence of a B ring is unfavorable for the biological activity and the double bond at C2-C3 in C-ring shows little effect on the activity.     

Mass spectrometry in the structural analysis of flavonoids

Flavonoids are very common and widespread secondary plant metabolites. They have a wide range of biological and physiological activities and serve as chemotaxonomic marker compounds. Therefore, they have been extensively investigated both in the past and during recent years. The interest in them is still increasing. In the search for new compounds, and also in quality control, there is a need to have reliable methodology for the analysis of flavonoids. Mass spectrometry can make an invaluable contribution because of its high sensitivity, possibilities of coupling with liquid chromatography and the availability of powerful tandem mass spectrometric techniques. A review of currently available mass spectrometric methodology used in the structure elucidation of flavonoids is presented. Sample preparation, liquid chromatographic/mass spectrometric analysis and tandem mass spectrometric procedures for the characterization of flavonoid aglycones, O-glycosides, C-glycosides and acylated glycosides are considered.     

Mass spectrometry in the structural analysis of flavonoids

The original article to which this Erratum refers was published in J. Mass Spectrom. 2004; 39 (1): 1–15. DOI:10.1002/jms.585. Copyright © 2004 John Wiley & Sons, Ltd.     

黄酮体化合物抗肿瘤活性的量子化学研究

本文对黄酮类化合物抗肿瘤活性进行了量子化学研究。采用从头算方法计算了黄酮体化合物的电荷分布，并基于电荷分布提出了黄酮体化合物表现抗肿瘤活性时与受体作用的模型：A环与受体的负电荷中心结构，C环与受体的正电荷中心结合，其他部分通过氢键与受体发生作用，氢键在受体的作用中起到很大的作用。     

Capillary electrophoretic analysis of flavonoids.

Combining the effects of electrophoresis and electroendosmosis, flavonoids were separated in less than ten minutes in a fused silica capillary tube with a borate buffer adjusted to pH 10. An increase in the concentration of borate from 0.1 to 0.2 M resulted in longer migration times due to a decrease in electroosmotic flow, but also in improved selectivity and higher resolution of flavonoids. The calibration curve of rutin showed a detection limit of 0.02 mg/mL and linearity over its pharmaceutical concentration range. Using an internal standard of known concentration, the content of rutin in a methanolic extract of Sambuci flos could be determined with a coefficient of variation as small as 3.8% by the molar ratio-peak area ratio method.     

Antimycobacterial activity of flavonoids from Lantana camara Linn

Linaroside (1) and lantanoside (2), two flavonoids isolated from Lantana camara and their common acetyl derivative (3) were examined for antimycobacterial activity against Mycobacterium tuberculosis, strain H(37)Rv. These compounds exhibited 30, 37 and 98% inhibition, respectively at 6.25 microg mL(-1) concentration. Among these flavonoids acetylated compound was found to be the most active.     

Use of sephadex in the analysis of some flavonoids

Chemistry of Natural Compounds - The conditions of gel filtration, through Sephadex of 14 different flavonoids have been studied. It has been shown that the structure of the flavonoid compound...     

Correlation between the structure and inhibiting activity of phenosan derivatives

Sterically hindered phenolic antioxidants (AOs) of the IKhFAN family are characterized as inhibitors of initiated oxidation of methyl oleate in homogeneous chlorobenzene solutions and in aqueous emulsions in the presence of dodecyl sulfate. The IKhFANs inhibit oxidation by scavenging peroxo radicals and by decomposing hydroperoxides to yield molecular products. The effect of an IKhFAN is governed by its chemical structure and by oxidation conditions. The IKhFANs slow down methyl oleate oxidation in lipid solution more effectively than comparable concentrations of -tocopherol, dibunol, phenosan K, or phenosan ester. The most effective is IKhFAN-10, in which the R³ radical is the shortest (CH₃). The inhibiting effect of the AOs weakens markedly with increasing chain length of R³. The specific features of the observed oxidation kinetics are explained by the formation of microheterogeneous systems involving AOs. In these systems, the phenolic OH groups are directed to the micelle center and, as a consequence, can hardly react with RO₂^· radicals. In the IKhFAN group in which R³ ranges from C₈H₁₇ to C₁₆H₃₃, the induction period grows in proportion to the number of carbon atoms. In an aqueous emulsion, the overall inhibiting effects of structurally different IKhFANs are similar and weaker than effects in homogeneous solution.Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 863–871Original Russian Text Copyright © 2004 by Storozhok, Perevozkina, Nikiforov, Rusina, Burlakov.     

Use of sephadex in the analysis of some flavonoids

Conclusions The conditions of gel filtration, through Sephadex of 14 different flavonoids have been studied. It has been shown that the structure of the flavonoid compound affects the filtration process.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 4, pp. 415–417, 1970     

Antibacterial activity of the flavonoids from Dalbergia odorifera on Ralstonia solanacearum

Phytohemical investigation on the heartwood of Dalbergia odorifera resulted in the isolation of nine flavonoids. Their structures were elucidated as sativanone (1), (3R)-vestitone (2), (3R)-2',3',7-trihydroxy-4'-methoxyisoflavanone (3), (3R)-4'-methoxy-2',3,7-trihydroxyisoflavanone (4), carthamidin (5), liquiritigenin (6), isoliquiritigenin (7), (3R)-vestitol (8), and sulfuretin (9) based on their spectral data. All compounds were evaluated for their inhibitory activity against Ralstonia solanacearum. This is the first report about anti-R. solanacearum activity of the compounds from D. odorifera.     

Identification of flavonoids by TLC scanning analysis

Summary A TLC-densitometric method for flavonoid analysis is described. Results are comparable to those obtained with classical methods. As the isolation step can be avoided results can be observed with 100 ng samples.