Three labdane diterpenoids from Aframomum sceptrum (Zingiberaceae)

Three labdane diterpenoids, 8beta,17-epoxy-3beta,7beta-dihydroxy-12(E)-labden-16,15-olide (1), methyl 8beta,17-epoxy-3beta,7beta,15-trihydroxy-12(E)-labden-16-oate (2) and 3beta,7beta,8beta,12zeta,17-pentahydroxylabdan-16,15-olide (3) have been isolated from the seeds of Afromomum sceptrum K. Schum (Zingiberaceae) and their structures assigned on the basis of their spectroscopic properties. Nerolidol, and the known flavonoids 3-acetoxy-4',5,7-trihydroxyflavanone, and 3,4',5,7-tetrahydroxyflavanone were also obtained.     

Geranylated flavanones from the secretion on the surface of the immature fruits of Paulownia tomentosa

Chemical investigation of the methanol extract of the viscous secretion on the surface of immature fruits of Paulownia tomentosa furnished nine geranylated flavanones, 6-geranyl-5,7-dihydroxy-3',4'-dimethoxyflavanone (1), 6-geranyl-3',5,7-trihydroxy-4'-methoxyflavanone (2), 6-geranyl-4',5,7-trihydroxy-3',5'-dimethoxyflavanone (3), 6-geranyl-4',5,5',7-tetrahydroxy-3'-methoxyflavanone (4), 6-geranyl-3,3',5,7-tetrahydroxy-4'-methoxyflavanone (5), 4',5,5',7-tetrahydroxy-6-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]-3'-methoxyflavanone (6), 3,3',4',5,7-pentahydroxy-6-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]flavanone (7), 3,3',4',5,7-pentahydroxy-6-[7-hydroxy-3,7-dimethyl-2(E)-octenyl]flavanone (8), and 3,4',5,5',7-pentahydroxy-3'-methoxy-6-(3-methyl-2-butenyl)flavanone (9), along with six known geranylated flavanones. Among these, compounds 4, 6-9 and the known 6-geranyl-3',4',5,7-tetraahydroxyflavanone (diplacone), 6-geranyl-3,3',4',5,7-pentahydroxyflavanone (diplacol) and 3',4',5,7-pentahydroxy-6-[7-hydroxy-3,7-dimethyl-2(E)-octenyl]flavanone showed potent radical scavenging effects towards DPPH radicals.     

Pyrano chalcones and a flavone from Neoraputia magnifica and their Trypanosoma cruzi glycosomal glyceraldehyde-3-phosphate dehydrogenase-inhibitory activities

The fruits of Neoraptua magnifica var. magnifica afforded three new flavonoids: 2'-hydroxy-4,4',-dimethoxy-5',6'-(2',2'-dimethylpyrano)chalcone, 2'-hydroxy-3,4,4'-trimethoxy-5',6'-(2',2'-dimethylpyrano)chalcone, and 3',4'-methylenedioxy-5,7-dimethoxyflavone which were identified on the basis of spectroscopic methods. The known flavonoids 2'-hydroxy-3,4,4',5-tetramethoxy-5',6'-(2',2'-dimethylpyrano)chalcone, 2'-hydroxy-3,4,4',5,6'-pentamethoxychalcone, 3',4'-methylenedioxy-5,6,7-trimethoxyflavone, 3',4'-methylenedioxy-5',5,6,7-tetramethoxyflavone, 3',4',5',5,7-pentamethoxyflavanone and 3',4',5'5,7-pentamethoxyflavone were also identified. The latter flavone was the most active as glyceraldehyde-3-phosphate dehydrogenase-inhibitor.     

No evidence for the in vivo activity of aromatase-inhibiting flavonoids

Measurements of the aromatase-inhibiting and antioxidative capacities of flavonoids in vitro showed that slight changes in flavonoid structure may result in marked changes in biological activity. Several flavonoids such as 7-hydroxyflavone and chrysin (5,7-dihydroxyflavone) were shown to inhibit the formation of 3H-17beta-estradiol from 3H-androstenedione (IC(50)<1.0 microM) in human choriocarcinoma JEG-3 cells and in human embryonic kidney cells HEK 293 transfected with human aromatase gene (Arom+HEK 293). Flavone and quercetin (3,3',4',5,7-pentahydroxyflavone) showed no inhibition (IC(50)>100 microM). None of the requirements for optimal antioxidative capacity (2,3-double bond with 4'-hydroxy group, 3-hydroxyl group, 5,7-dihydroxy structure and the orthodihydroxy structure in the B-ring) is relevant for the maximum inhibition of aromatase by flavonoids. After oral administration to immature rats at a dose of 50 mg/kg body weight, which considerably exceeds amounts found in daily human diets, neither aromatase-inhibiting nonestrogenic flavonoids, such as chrysin, nor estrogenic flavonoids, such as naringenin and apigenin, induced uterine growth or reduced estrogen- or androgen-induced uterine growth. The inability of flavonoids to inhibit aromatase and, consequently, uterine growth in short-term tests may be due to their relatively poor absorption and/or bioavailability.     

Flavonoids from the aquatic plant Eriocaulon buergerianum

Four flavonoids including (2S)-3',4'-methylenedioxy-5,7-dimethoxyflavan and hispidulin 7-(6-E-p-coumaroyl-beta-D-glucopyranoside), and one tocopherol were isolated from the capitulum of Eriocaulon buergerianum KOERN. Their structures were established by spectral and chemical evidence.     

Bioavailable flavonoids to suppress the formation of 8-OHdG in HepG2 cells

Antioxidative flavonoids, ubiquitously included in vegetables, fruits and teas, are expected to prevent degenerative diseases. It is unclear, however, whether flavonoids can enter the cellular nuclei and suppress the oxidative damage of DNA. Here, several flavonoids at the physiological concentration of 10 microM were dosed to 2.5x10(7) HepG2 cells. The nuclei were isolated and determined in the incorporated flavonoid levels, and simultaneously exposed to reactive oxygen generated from 25 mM of 2,2'-azobis(2-amidinopropane) dihydrochloride. Most of the tested flavonoids were incorporated into the cells in the range between 1000 and 1600 pmol/10(7) cells, and were in the nuclei at 250-450 pmol/10(7) cells at the maximum incorporation after 30min of cell incubation. In the cells, 23% of quercetin (3,5,7,3',4'-OH) and 8% of luteolin (5,7,3',4'-OH) were the original aglycone forms and the others were the methylated and gulucuronide/sulfate conjugates, while 72% of kaempferol (3,5,7,4'-OH) and 85% of apigenin (5,7,4'-OH) were aglycones and located in the nuclei at the similar ratio of metabolites. Quercetin and luteolin significantly suppressed the formation of 8-oxo-7,8-dihydrodeoxyguanosine by 25% and 15%, respectively, compared to those in 0-time incubated cells with the flavonoids. Under such conditions of low level and hydroxyl-masked in the nuclei, the limited flavonoids were bioavailable antioxidants to prevent genetic damage and they were B-ring catechols such as quercetin and luteolin.     

Assessment of estrogenic activity of flavonoids from Mediterranean plants using an in vitro short-term test

Six isoflavones, daidzein (4',7,-dihydroxyisoflavone), genistein (4',5,7-trihydroxyisoflavone), genistin (genistein 7-O-beta-D-glucopyranoside), isoprunetin (4',7-dihydroxy, 5-metoxyisoflavone), isoprunetin 7-O-beta-D-glucopyranoside, isoprunetin 4',7-di-O-beta-D-glucopyranoside and four flavones, luteolin (3',4',5,7-tetrahydroxyflavone), luteolin 7-O-beta-D-glucopyranoside, luteolin 4'-O-beta-D-glucopyranoside, licoflavone C (4',5,7-trihydroxy,8-isoprenylflavone) were purified from Mediterranean plants (Genista morisii and Genista ephedroides) and their estrogenic activity was assessed by a yeast reporter gene assay (Saccharomyces cerevisiae RMY326 ER-ERE). Licoflavone C showed a powerful estrogenic activity at 10(-7) M (0.0338 microg/ml) and it was 47.45% than 10(-8) M 17beta-estradiol (0.00272 microg/ml). The estrogenicity of this flavone was found to be comparable to the activity showed by genistein at 10(-6) M (0.27 microg/ml). This study points out that a glucose substituent in flavones and isoflavones modulates the hormone-like activity in a different way. Isoflavone aglycones showed a more estrogenic activity than the corresponding glucosides. Conversely, the glucosidation made estrogenic the flavone luteolin and the position of substitution differently influenced the estrogenic activity of compounds.     

樱草杜鹃中的黄酮类化合物

从樱草杜鹃（Rhododendron primulaeflorum）地上部分的乙醇提取物中分离得到10个黄酮类化合物,经理化性质及波谱分析,鉴定为杜鹃素（1）、4’,5,7-三羟基-8-甲基黄烷酮（2）、二氢山柰酚（3）、异鼠李素（4）、槲皮素（5）、陆地棉苷（6）、瑞诺苷（7）、（2R,3R）－花旗松素-3—O-α-L-吡喃阿拉伯糖苷（8）、（2R,3S）-花旗松素-3—O-α-L-吡喃阿拉伯糖苷（9）、（2S,3R）－花旗松素－3－O－α－L－吡喃阿拉伯糖苷（10）。所有化合物均为首次从该植物中分得。     

Antioxidant flavonoids from leaves of Polygonum hydropiper L

Ten flavonoid compounds were isolated from the dried leaves of Polygonum hydropiper L. (Laksa leaves), and identified as 3-O-alpha-L-rhamnopyranosyloxy-3',4',5,7-tetrahydroxyflavone; 3-O-beta-D-glucopyranosyloxy-4',5,7-trihydroxyflavone; 6-hydroxyapigenin; 6"-O-(3,4,5-trihydroxybenzoyl) 3-O-beta-D-glucopyranosyloxy-3', 4', 5, 7-tetrahydroxyflavone; scutillarein; 6-hydroxyluteolin; 3',4',5,6,7-pentahydroxyflavone; 6-hydroxyluteolin-7-O-beta-D-glucopyranoside; quercetin 3-O-beta-D-glucuronide; 2"-O-(3,4,5-trihydroxybenzoyl) quercitrin; quercetin. Evaluation of the antioxidative activity, conducted in vitro, by using electron spin resonance (ESR) and ultraviolet visible (UV-vis) spectrophotometric assays, showed that these isolated flavonoids possess strong antioxidative capabilities. Measurement of the Trolox equivalent antioxidant capacity (TEAC) values, against ABTS (2,2'-azinobis(3-ethyl-benzo-thiazoline-6-sulphonic acid) radicals and phenyl-tert-butyl nitrone (PBN) azo initiator (AI) also showed strong anti-oxidative activity. The most powerful of the antioxidants was 2"-O-(3,4,5-trihydroxybenzoyl) quercitrin (galloyl quercitrin). A combination of two flavonoid compounds was tested for synergistic anti-oxidative capacity, but no significant improvement was observed.     

Comparative mutagenesis of plant flavonoids in microbial systems.

The plant flavonoids quercetin (3,5,7,3',4'-pentahydroxyflavone), morin (3,5,7,2',4'-pentahydroxyflavone), kaempferol (3,5,7,4'-tetrahydroxyflavone), chrysin (5,7-dihydroxyflavone), fisetin (3,7,3',4'-tetrahydroxyflavone), myricetin (3,5,7,3',4',5'-hexahydroxyflavone), myricitrin (myricetin-3-rhamnoside), hesperetin (3',5,7-trihydroxy-4'-methoxyflavanone), quercitrin (quercetin-3-L-rhamnoside), rutin (quercetin-3-rhamnosylglucoside or quercetin-3-rutinoside), and hesperidin (hesperetin-7-rutinoside) have been assayed for mutagenicity in the Salmonella/microsomal activation system. Quercetin, morin, kaempferol, fisetin, myricetin, quercitrin and rutin were mutagenic in the histidine reversion system with the frameshift strain TA98. The flavonols quercetin and myricetin are mutagenic without metabolic activation, although more effective when a rat liver microsomal preparation (S-9) is included; all others require metabolic activation. Flavonoids are common constituents of higher plants, with extensive medical uses. In addition to pure compounds, we have examined crude extracts of tobacco (snuff) and extracts from commonly available nutritional supplements containing rutin. Mutagenic activity can be detected and is correlated with the flavonoid content.     

Isoflavanones and their O-glycosides from Desmodium styracifolium

Two isoflavanones (5,7-dihydroxy-2',3',4'-trimethoxy-isoflavanone and 5,7-dihydroxy-2'-methoxy-3',4'-methylenedioxy-isoflavanone), four isoflavanone O-glycosides (5,7-dihydroxy-2',3',4'-trimethoxy-isoflavanone 7-O-beta-glucopyranoside, 5,7-dihydroxy-2'-methoxy-3',4'-methylenedioxy-isoflavanone 7-O-beta-glucopyranoside, 5,7-dihydroxy-2',4'-dimethoxy-isoflavanone 7-O-beta-glucopyranoside, and 5,7,4'-trihydroxy-2',3'-dimethoxy-isoflavanone 7-O-beta-glucopyranoside), and a coumaronochromone (3,5,7,4'-tetrahydroxy-coumaronochromone), along with 25 known compounds, were isolated from the aerial parts of Desmodium styracifolium. This is for the first time isoflavanone O-glycosides were isolated from a natural source.     

Flavonoids and terpenoids from Luma gayana (Barn.) Burret

The flavonoids 5-hydroxy-7-methoxyflavanone, 6,8-dimethyl-5,7-dihydroxyflavanone and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone, a mixture of alkyl esters of p-coumaric acid, the triterpenoids oleanolic acid and maslinic acid, the monoterpenoid 1 alpha,2 beta,4 beta-trihydroxy-p-menthane, the sesquiterpenoid clovandiol and beta-sitosterol were isolated from the aerial parts of Luma gayana (Barn.) Burret. This is the first report on the chemistry of this species.     

Antibacterial and antifungal flavanones from Eysenhardtia texana

An activity-guided fractionation of a methanol-dichloromethane extract obtained from the aerial parts of Eysenhardtia texana led to the isolation of two novel antibacterial and antifungal flavanones together with a known flavanone. Their structures were established as 4',5,7-trihydroxy-8-methyl-6-(3-methyl-[2-butenyl])-(2S)-flavanone, 4',5,7-trihydroxy-6-methyl-8-(3-methyl-[2-butenyl])-(2S)-flavanone and 4',5-dihydroxy-7-methoxy-6-(3-methyl-[2-butenyl])-(2S)-flavanone on the basis of their UV, 1D and 2D-NMR spectra.     

Natural PTP1B inhibitors from Broussonetia papyrifera

Two new compounds, 8-(1,1-dimethylallyl)-5'-(3-methylbut-2-enyl)-3',4',5,7-tetrahydroxyflanvonol (1), 3'-(3-methylbut-2-enyl)-3',4',7-trihydroxyflavane (2) and three known compounds 3,3',4',5,7-pentahydroxyflavone (3), uralenol (4), broussochalcone A (5) were isolated from the roots of Broussonetia papyrifera, and their structures determined by spectroscopic methods. Compounds 1, 3, 4 and 5 significantly show the inhibitory activities against the PTP1B enzyme.     

半卧狗娃花中的黄酮类化合物

从半卧狗娃花(Heteropappus semiprost Griers)全草的乙醇提取物中分离并鉴定了7个黄酮类化合物,通过波谱分析及化学方法鉴定其结构为:3′,4′,5,7-四羟基黄酮(1),3′-甲氧基槲皮素(2),槲皮素-3-O-α-L-吡喃鼠李糖甙(3),槲皮素-3-O-β-D-吡喃半乳糖甙(4),异鼠李亭-3-O-β-D-吡喃半乳糖甙(5),槲皮素-3-O-α-L-吡喃鼠李糖(1→6)-β-D-吡喃葡萄糖甙(6),异鼠李亭-3-O-α-L-吡喃鼠李糖(1→6)-β-D-吡喃葡萄糖甙(7),其中化合物1~5为首次从本属植物中分离得到。     

Anti-inflammatory and antinociceptive activity of flavonoids isolated from Viscum album ssp. album

Viscum album L. has been used in the indigenous systems of medicine for treatment of headache and some inflammatory diseases. In order to evaluate this information, antinociceptive and anti-inflammatory activities of the five flavonoids (5,7-dimethoxy naringenin or 4',6'-dimethoxy chalcononaringenin) derivatives, isolated from the ethyl acetate fraction of the extract from V. album ssp. album, were investigated, namely 5,7-dimethoxy-flavanone-4'-O-beta-D-glucopyranoside (1), 2'-hydroxy-4',6'-dimethoxy-chalcone-4-O-beta-D-glucopyranoside (2), 5,7-dimethoxy-flavanone-4'-O-[2"-O-(5"'-O-trans-cinnamoyl)-beta-D-apiofuranosyl]-beta-D-glucopyranoside (3), 2'-hydroxy-4',6'-dimethoxy-chalcone-4-O-[2"-O-(5"'-O-trans-cinnamoyl)-beta-Dapiofuranosyl]-beta-D-glucopyranoside (4), 5,7-dimethoxy-flavanone-4'-O-[beta-D-apiofuranosyl-(1 --> 2)]-beta-D-glucopyranoside (5). For the antinociceptive activity assessment the p-benzoquinone-induced writhing test and for the anti-inflammatory activity the carrageenan-induced hind paw edema model in mice were used. The ethyl acetate fraction in a dose of 250 mg/kg as well as compounds 2 and 5 in a 30 mg/kg dose were shown to possess remarkable antinociceptive and anti-inflammatory activities per os without inducing any apparent acute toxicity as well as gastric damage.     

Flavonoids from Andrographis lineata

Three flavonoids, 5,7,2',3',4'-pentamethoxyflavone (1), 2'-hydroxy-2,4',6'-tri methoxychalcone (2) and dihydroskullcapflavone I (3), together with 17,19,20-trihydroxy-5beta, 8alpha H, 9beta H,10alpha-labd-13-en-16,15-olactone (4), a known diterpenoid and six known flavonoids, 5-hydroxy-7,8-dimethoxyflavanone (5), 5-hydroxy-7,8,2',3',4'-pentamethoxyflavone (6), 5,2'-dihydroxy-7-methoxyflavanone (7), 5,2'-dihydroxy-7,8-dimethoxyflavone (8), 5,2'-dihydroxy-7-methoxyflavone (9) and 5,2'-dihydroxy-7-methoxyflavone 2'-O-beta-D-glucopyranoside (10) were isolated from the whole plant of Andrographis lineata. The structures of these compounds were elucidated on the basis of spectral and chemical studies.     

Geranylated phenolic constituents from the fruits of Artocarpus nobilis

Chemical investigation of the combined dichloromethane and ethyl acetate extracts of the fruits of Artocarpus nobilis, furnished four new geranylated phenolic constituents, 2,4,4'-trihydroxy-3-[(2E)-5-methoxy-3,7-dimethylocta-2,6-dienyl]chalcone (4), 1-(3,4-dihydro-3,5-dihydroxy-2-methyl-2-(3-methyl-2-butenyl)-2H-1-benzopyran-6-yl-3-(4-hydroxyphenyl)-2(E)-propen-1-one (5), 8-geranyl-3',4',7-trihydroxyflavone (8), 3'-geranyl-4',5,7-trihydroxyflavanone (9), together with known related compounds, xanthoangelol (1), xanthoangelol B (2), 3-geranyl-2,3',4,4'-tetrahydroxychalcone (3), lespeol (6), 8-geranyl-4',7-dihydroxyflavanone (7), and isonymphaeol-B (10). Compounds 3, 8 and 10 showed strong antioxidant activity against DPPH radical by spectrophotometric method.     

High-performance liquid chromatographic analysis of genistein and other isoflavonoids from heartwood of Ougeinia dalbergioides

A simple binary gradient HPLC method employing a Symmetry C18 column is described for the analysis of genistein, ougeinin, homoferririn, 2',4',5,7-tetrahydroxy-6-methyl isoflavone and 2',4',8-trihydroxy-6-methoxy-7-methyl isoflavone present in heartwood extract of Ougeinia dalbergioides.