Synthesis of Lupinine Derivatives of Flavonoids

The isomerization and oxidative cyclization of 2-hydroxy-4-lupinylchalcones leads to the corresponding 7-lupinylflavanones and 7-lupinylflavones.     

Flavonoids from Flindersia australis

Dihydrokaempferol, dihydrokaempferol 3-O-rhamnoside (engeletin) and kaempferol were isolated from the stem bark of Flindersia australis. This is the first report of the occurrence of these flavonoids in Flindersia.     

Novel flavonoids from the stem of Popowia cauliflora

Six flavonoids, five of them novel, have been isolated from the whole stem of Popowia cauliflora and identified as: baicalein trimethyl ether, 5-hydroxy-6,7-dimethoxyflavone, 5,7,8-trimethoxyflavanone, 2′-hydroxy-3′,4′,6′-trimethoxychalcone, 2′,3′,4′,6′-tetramethoxychalcone and 2′,4-dihydroxy-3′,4′,6′-trimethoxychalcone, on the basis of spectral data and simple chemical modifications. The value of ¹³C NMR in assigning the positions of methoxy substituents is briefly discussed.     

Flavonoids from the seeds of Lonchocarpus costaricensis

Seven flavonoids have been isolated from the seeds of Lonchocarpus costaricensis of which four appear to be novel. The new compounds have been identified as the β-hydroxychalcone demethylpraecansone-B and the flavanones 7-(3,3-dimethylallyloxy)-8-(3-hydroxy-3-methyl-trans-but-1-enyl)flavanone, 7-(3,3-dimethylallyloxy)-8-(3,3-dimethylallyl)-5-methoxyflavanone and 8-(3,3-dimethylallyl)-5,7-dimethoxyflavanone.     

Synthetic flavonoids with antimicrobial activity: a review

The emergence of drug-resistant microbes left us with a great need for new antimicrobial agents. Flavonoids, with their wide range of biological activities, are good candidates in this respect. Although naturally occurring flavonoids are the most studied ones, semi-synthetic or synthetic flavonoids have proven to have great potential, inhibiting and even killing microbes at concentrations below 1 μg ml⁻¹. The substitution pattern of these flavonoids often includes hydroxy groups, halogens or other heteroatomic rings, such as pyridine, piperidine or 1,3-dithiolium cations. However, the great variety in substituents makes it difficult to draw any definitive conclusion regarding their structure–activity relationship.     

Flavones and diterpenes of Pamburus missionis (rutaceae)

A new flavone and two diterpenes have been isolated from the extracts of Pamburus missionis. The flavone was identified as an isopentylated apigenin derivative on the basis of spectroscopic studies on it and its diacetate. One of the diterpenes has been identified as daniellic acid and the second as a closely related butenolide.     

Flavonoids from Artemisia frigida

Twelve flavonoids including a new flavone were isolated from Artemisia frigida. The structure of the new highly oxygenated flavone was determined b     

Flavonoids of Plagiochila asplenioides

Besides an apigenin- and a luteolin-di-C-glycoside, 5 previously unknown di-C-glycosides of tricetin were identified in the gametophytic and sporophytic tissues of Plagiochila asplenioides. Two of them were new 6,8-di-C-hexopyranosyltricetins, and two were new 6-C- hexopyranosyl-8-C-pentopyranosyltricetins. 6-C-Hexopyranosyl-8-C-pentopyranosyltricetin-5′-methyl ether was also found.     

Flavonoids and polyacetylenes in Dahlia tenuicaulis

5,7,4′-Trimethoxyflavanone, 5-hydroxy-7,4′-dimethoxyflavanone, 2′-hydroxy-4,4′,6′-trimeth-oxychalcone, and a new naturally occurring compound, 5,7,4′-trimethoxyflavan-4-ol have been isolated from the leaves of Dahlia tenuicaulis Sorensen. Two chalcones, 4,2′,4′-trihydroxychalcone and 3,2′,4′-trihydroxy-4-methoxychalcone, and 5-hydroxy-7,4′-dimethoxyflavanone have been isolated from the flower heads. Minute amounts of the polyacetylene 1,3-diacetoxy-tetradeca-4,6-diene-8,10,12-triyne have been found in both leaves and flower heads, whereas 1-acetoxy-tetradeca-4,6-diene-8,10,12-triyne was present only in the flower heads.     

Six new flavonoids from Citrus

Valencia orange (C. sinensis) and Robinson tangerine [(C. paradisi × C. reticulata) × (C. reticulata)] were examined for flavonoids. Thirteen flavonoids were isolated, six of which are new constituents of citrus peel. These are: 3,5,6,7,3′,4′-hexamethoxyflavone, 3,5,7,8,3′,4′-hexamethoxyflavone, 5-hydroxy-3,7,8,3′,4′-pentamethoxyflavone, 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone, 5,7,8,4′-tetramethoxyflavone and 5,7,8,3′,4′-pentamethoxyflavone. The latter three flavonoids are reported for the first time as natural products. A method is described for readily obtaining small quantities of 5,7,8,4′-tetramethoxy and 5,7,8,3′,4′-pentamethoxyflavones from their 5,6,7-trimethoxy analogs.     

Flavonoids of Chromolaena odorata

A dichloromethane extract of Chromolaena odorata has yielded 2′-hydroxy-3,4,4′,5′,6′-pentamethoxychalcone, 2′,4-dihydroxy-4′,5′,6′-     

Flavonoids and coumarins from Platymiscium praecox

The wood of Platymiscium praecox Mart. (Leguminosae-Lotoideae) contains sitosterol, 4,2′,4′-trihydroxychalcone, (2R)-7-hydroxyflavanone, (±)-7,4′-dihydroxyflavanone, (2S, 3S)-3,7-dihydroxyflavanone, 3,7-dihydroxyflavone, 3,7,4′-trihydroxyflavone, 6,7-dihydroxy-4′-methoxyisoflavone and 6,7-dimethoxycoumarin. It also contains three novel compounds: 7-hydroxy-4-methoxy-5-methylcoumarin, 7-O-glucosyloxy-4-methoxy-5-methylcoumarin and 7-hydroxy-4,8-dimethoxy-5-methylcoumarin.     

Flavonoids from the stem bark of Millettia hemsleyana

The stem bark of Millettia hemsleyana has yielded six simple flavonoids of which three are novel. Dihydromilletenone methyl ether and dihydroisomilletenone methyl ether represent the two keto—enol tautomers of the known β-hydroxychalcone milletenone, trapped by methylation and reduction, and the third new compound, 3′,4′-methylenedioxy-7-methoxyflavone, is the cyclized form of a demethylated milletenone. All compounds were identified on the basis of detailed spectral analysis.     

响应面法优化红景天总黄酮提取工艺的研究

研究了红景天中总黄酮提取率的影响因素,先经单因素实验初步确定影响因素,再用Box-Behnken响应面法建立影响因素的二次回归模型,通过对二次回归模型求解编码转换得知,液料比40:1(ml/g),酶添加量1.2%,酶解时间4.5 h,酶解温度45℃,pH5,超声时间为12 min,超声功率为250w中的高档,超声次数为3次,在这最优条件下总黄酮提取率为3.99%。     

Flavonoids from Haplophyllum pedicellatum, H. robustum AND H. glabrinum

Haplophyllum pedicellatum, H. robustum and H. glabrinum all yielded the known compound gossypetin 8,3′-dimethyl ether 3-rutinoside. In addition the first two species afforded isorhamnetin and its 3-rutinoside. A new glycoside, gossypetin 8,3′-dimethyl ether 3-glucoside was obtained from H. pedicellatum together with the 3-malonylrutinoside, 3-malonylglucoside and 3-galactoside of isorhamnetin plus kaempferol 3-malonylglucoside. H. robustum yielded isorhamnetin 7-glucoside and 3-glucoside and quercetin 3-galactoside, while H. glabrinum was found to contain gossypetin 8-methyl ether 3-malonylrutinoside in addition to kaempferol and isorhamnetin 3-glucoside.     

Chemotaxonomic Studies in Ferula of China on the Basis of Flavonoids

Sixteen species of Ferula L. (Umbelliferae) were examined for their leaf flavonoids, and at least 9 glycosides of quercetin, kaempferol and apigenin are detected in 13 species. While most of the constituents reported are common in the Umbelliferae, the unusual one, apigenin-6, 8-C-diglucoside, which was found in Ostericum Hoffm. in an earlier survey has been detected in F. moschata (F. sumbul) The three species (F. sinkiangensis, F. fukangensis and F. krylovii) from which flavonoids have not been found, are all medicinal plants with strong garliky odor due to a high concentration of essential oils containing disulfides. The subgenus Peucedanoides is found to be rich in quercetin glycosides, and the aglycon pattern seems to have some relationship with habitat conditions in the genus: the species occurring in comparatively humid habitats are often large herbs and often characterized by the presence of quercetin, while those growing in dry habitats contain apigening kaepferol, as well as quercetin. Nevertheless, any conclusion with certainty needs examining more species of the genus. It is interesting to note that F. moschata, from which the glycosylapigenin was found, and F. pseudooreoselinum, which probably has a trace amount of kaempferol glycoside, are peculiar in Ferula in their inflorescence morphology. The phytochemic results also raise a suspicion against their systematic position within the genus. F. bungeana, previously placed in the subgenus Peucedanoides, has relatively great similarities with F. syreitschkowii of the subgenus Narthex in their general morphology and fruit anatomy. In the present survey apigenin-7-glycoside is detected from both, and thus it seems more suitable to transfer the former species into the subgenus Narthex. The same compounds have been found in F. licentiana and F. tunshanica, which also share the characters of morphology and anatomy. The fact does support the view that the lattershould be included in F. licentiana as a variety.     

高山金粉蕨的黄酮类成分

从高山金粉蕨(Onychiumcontigqum)地上部分的甲醇抽提物中分到8个成分:高山金粉蕨甲甙(1),高山金粉蕨乙甙(2),金粉蕨素(3),反式桂皮酸(4),瓦利甙(5),β-谷甾醇(6),胡萝卜甙(7)和蔗糖(8)。高山金粉蕨甲甙和乙甙是新成分,反式桂皮酸系首次从金粉蕨属中分到。化学结构用一维和二维核磁共振技术确定。