New flavonoids from Inula cappa

Extraction of Inula cappa DC. yielded three new flavonoids with an unusual ring B substitution pattern, namely (2R,3R)-5′-methoxy-3,5,7,2′-tetrahydroxyflavone, (2S)-5,7,2′,5′-tetrahydroxyflavanone and 7.5′-dimethoxy- 3,5,2′-trihydroxyflavone. Structures were established by chemical correlation, spectroscopic studies and degradation.     

Relationships between structures of hydroxyflavones and their antioxidative effects

Even hydroxyflavones show diverse biological functions, they have two common features such as showing antioxidative effects and containing hydroxyl groups. The authors tested the antioxidative effects of thirty hydroxyflavones using 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay. While the scavenging activity of galangin, 3,5,7-trihydroxyflavone was 52.5%, fisetin, 3,7,3′,4′-tetrahydroxyflavone showed 85.2%. To investigate the relationships between the structures of hydroxyflavones and their antioxidative effects, the three-dimensional quantitative structure–activity relationships were examined.     

Hispidulin protection against hepatotoxicity induced by bromobenzene in mice

The effects of the natural flavonoid hispidulin (6-methoxy-5, 7, 4′-trihydroxyflavone) on bromobenzene-induced hepatotoxicity in mice were investigated. We found a correlation between liver injury and hepatic lipid peroxidation besides a strong liver glutathione depletion due to the toxicant. Hispidulin at doses between 50 and 150 mg/kg i.p. compared favourably with the reference compound N-acetyl-L-cysteine for inhibition of liver injury and lipid peroxidation. The flavonoid at the highest dose tested was also able to counteract reduced glutathione depletion induced by bromobenzene in starved mice. These hepatoprotective effects can be related to the antioxidant properties of hispidulin.     

Myricetin methyl ethers from Solanum pubescens

3,7,3′,5′-Tetramethoxy-5,4′-dihydroxyflavone and a novel flavonol 3,7,3′-trimethoxy-5,4′,5′-trihydroxyflavone were isolated from the leaves of Solanum pubescens and characterized by both physical and chemical methods.     

A 5, 6-dimethoxylated flavone in the leaf resin of Adenostoma sparsifolium

A new flavone 5,6-dimethoxy-3,7,4′-trihydroxyflavone was isolated from the external leaf resin of Adenostoma sparsifolium and identified by spect     

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.     

Benzofuranoid neolignans from Aniba simulans

Forteen neolignans, isolated from the benzene extract of Aniba simulans (Lauraceae) trunk wood, included the hitherto undescribed (2S, 3S, 5R)-5-allyl-5,7-dimethoxy-2-(3′,4′,5′-trimethoxyphenyl)-3-methyl-2,3,5,6-tetra-hydro-6-oxobenzofuran, (2R,3S,5R) -5-allyl-5-methoxy-2-(3′-methoxy-4′,5′-methylenedioxyphenyl)-3-methy1-2,3,5, 6-tetrahydro-6-oxobenzofuran, (2S,3S)-6-O-allyl -5-methoxy-2-(3′-methoxy-4′-5′-methylenedioxyphenyl)-3-methyl-2,3-dihydrobenzofuran, (2R,3S)-6-O-allyl-5-methoxy-2- (3′-methoxy-4′,5′-methylenedioxyphenyl)-3-methyl-2,3-dihydrobenzofuran and 7-allyl-6-hydroxy-5-methoxy-2-(3′-methoxy-4,5′ -methylenedioxyphenyl)-3-methylbenzofuran.     

3,5,7,3′,5′-Pentahydroxyflavan and 3α-methoxyfriedelan from Humboldtia laurifolia

The leaf, bark and timber extractives of Humboldtia laurifolia were investigated and the following compounds have been isolated: O-acetyloleanolic aldehyde, a sitosteryl ester, lupeol, sitosterol, a fatty acid, 5,7,4′-trihydroxyflavone (apigenin), (2R,3R)-3,5,7,3′,5′-pentahydroxyflavan and 3α-methoxyfriedelan. The latter two compounds are new natural products.     

Four 6-hydroxyflavonols from Blumea malcomii

Four new 6-hydroxyflavonols have been isolated from Blumea malcolmii and identified as 6-hydroxy-3,5,7,4′-tetramethoxyflavone, 6,2′,5′-trihydroxy-3,5,7-trimethoxyflavone, 6,5′-dihydroxy-3,5,7,2′-tetramethoxyflavone and 6-hydroxy-3,5,7,2′,5′-pentamethoxyflavone, by spectral data coupled with some chemical correlations.     

艾纳香化学成分的研究

从艾纳香(Blumea balsamifera DC.)中分离得到12个化合物,通过理化性质和波谱数据分析分别鉴定为;商路素(1),花椒油素(2),2,4-二羟基-6-甲氧基苯乙酮(3),5,7-二羟基色原酮(4),金丝桃苷(5),异槲皮苷(6),3′,4′,5,7-四羟基-3-甲氧基黄酮(7),槲皮素(8),槲皮素-3′-甲氧基-3-O-β-D-半乳吡喃糖苷(9),4′,5,7-三羟基-3,3′-二甲氧基黄酮(10),3,5,7-三羟基-3′,4′-二甲氧基黄酮(11),木犀草素(12).其中,化合物3-7和9- 11为首次从该属植物中分离得到.     

Flavonoids from the root-bark of Dioclea grandiflora

The systematic investigation of the root-bark of Dioclea grandiflora permitted the isolation of three new flavanones: agrandol (5,7-dihydroxy-6-methoxy-8-prenylflavanone), paraibanol (3,5,7,2′,5′-pentahydroxy-6-methoxyflavanone), and diosalol (3,5,7,2′,5′-pentahydroxy-6-methoxy-8-prenylflavanone). Also identified were β-amyrin and 5,7,2′,5′-tetrahydroxy-6-methoxy-8-prenylflavanone. All structural assignments were based solely on spectral data.     

Flavonoids in the black rhizomes of Boesenbergia panduta

5-Hydroxy-7-methoxyflavanone, 5,7-dimethoxyflavanone, 5-hydroxy-7-methoxyflavone 5-hydroxy-7,4′-dimethoxyflavone, 5,7-dimethoxyfiavone, 5,7,4′-trimethoxyflavone, 5,7,3′,4′-tetramethoxyflavone, 5-hydroxy-3,7-dimethoxyflavone, 5-hydroxy-3,7,4′-trimethoxyflavone, 3,5,7-trimethoxyflavone and 5-hydroxy-3,7,3′,4′-tetramethoxyflavone have been isolated from the black rhizomes of Boesenbergia pandurata.     

Dimeric hydroanthracenes from the unripe seeds of Cassia torosa

From the unripe seeds of Cassia torosa three new dimeric hydroanthracene derivatives were isolated along with stigmasterol, sitosterol, campesterol, physcion-9-anthrone, torosachyrsone and the phlegmacins A₂ and B₂. The structures of the new derivatives were established as physcion-10, 10′-bianthrone, anhydrophlegmacin B₂ [2-(6′-methoxy-3′-methyl-3′, 8′, 9′-trihydroxy-1′-oxo-1′, 2′, 3′, 4′-tetrahydroanthracene-10′-yl)-1, 8-dihydroxy-3-methoxy-6-methyl-9-oxo-9, 10-dihydroanthracene] and torosanin [2-(6′-methoxy-3′-methyl-3′, 8′,9′-trihydroxy-1′-oxo-1′, 2′, 3′,4′-tetrahydroanthracene-5′-yl)-1, 8-dihydroxy-3-methoxy-6-methyl-9-oxo-9, 10-dihydroanthracene], respectively.     

B-ring substituted 5,7-dihydroxyflavonols with high-affinity binding to P-glycoprotein responsible for cell multidrug resistance

Starting from the interaction of galangin (3,5,7-trihydroxyflavone) with a cytosolic nucleotide-binding domain of P-glycoprotein, a series of flavonol derivatives was synthesized and tested for their binding affinity towards the same target. The 5,7-dihydroxy-4'-iodoflavonol and 5,7-dihydroxy-4'-n-octylflavonol derivatives displayed much higher binding affinities, with respective increases of 6- and 93-fold as compared to galangin.     

Flavonoids and the chemotaxonomy of three Sophora species

Sophora microphylla, S. prostrata and S. tetraptera are distinguishable from one another by their leaf flavonoids. S. microphylla is distinguished by the present of rhamnosylvitexin and rhamnosylisovitexin and S. tetraptera by the presence of apigenin-7-O-rhamnosylglucoside-4′-O-glucoside and the 7-O-glucosides of apigenin, 7,4′-dihydroxyflavone, luteolin and 7,3′,4′-trihydroxyflavone. Sophora prostrata lacks all these flavonoids, but has several pigments which are common to all three species.     

Bioactivity guided isolation of anticancer constituents from leaves of Alnus sieboldiana (Betulaceae)

The leaves of the Japanese Alnus sieboldiana have been extracted with n-hexane and then with methanol. A bioactivity-guided approach based on MTT assay for growth inhibition and quantitative real-time PCR for TNF-α inhibitory activity was taken to identify the active compounds in EtOAc soluble fraction of the methanol extract. From this active fraction, seven compounds have been isolated and four compounds (pinosylvin, galangin, quercetin and methyl gallate) have been examined for their dose-response effect on the viability of A549 cells and on TNF-α inhibitory activity. Based on MTT assay, all of the four examined compounds inhibit growth of human lung cancer cells. Among four tested compounds only galangin (3,5,7-trihydroxyflavone) significantly inhibited TNF-α gene expression in A549 cells (IC₅₀ = 94 μM). Taken together, this finding suggests that galangin may be useful in cancer prevention.     

Bausplendin,a dimethylenedioxyflavone from Bauhinia splendens

Wood of Bauhinia splendens, an Amazonian creeper, contains bausplendin, 7-methoxy-5,6,3′,4′-dimethylenedioxyflavone, as shown by spectral analysis and synthesis of the isomeric 5-methoxy-7,8,3′,4′-dimethylenedioxyflavone.     

Neolignans of Virola carinata bark

Four neolignans, dehydrodieugenol, its monomethylether, carinatone and carinatin have been isolated from the hexane fraction of the bark of Virola carinata. Three new neolignans were separated from the chloroform fraction and examined by spectroscopy and chemical reactions. Their structures were determined as (2S, 3S)-5-allyl- 7-methoxy-3-hydroxymethyl-2-(3′,4′-dimethoxyphenyl)-2,3-dihydrobenzofuran, (2S)- 1-(3′,4′-dimethoxyphenyl)-2-(3″-allyl-5″-methoxy-6″-hydroxyphenyl)propanone(1) ol(3), (1S,2S)-1-(3′,4′-dimethoxyphenyl)-2-(3″-allyl-5″-methoxy-6″-hydroxyphenyl) propanol(1) and called dihydrocarinatinol, carinatonol and carinatol, respectively.     

Neolignans from the fruits of Licaria armeniaca

Fruits of Licaria armeniaca contain, besides eight known lignoids, three novel neolignans: (1S,5R,6S,7R,8R)-8-acetoxy-1-allyl-3,5-dimethoxy-7-methyl-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-4-oxobicyclo[3.2.1]oct-2-ene; (1S,5R,6S,7R)-1-allyl-3-methoxy-7-methyl-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-4,8-dioxobicyclo[3.2.1]oct-2-ene and (1S,5R,6S,7R)-1-allyl-3-methoxy-7-methyl-6-(3′,4′,5′-trimethoxyphenyl)-4,8-dioxobicyclo[3.2.1]oct-2-ene.     

Bicyclo[3,2,1]octanoid,neolignans from Aniba simulans

Six bicyclo[3,2,1]octanoid neolignans, isolated from the benzene extract of Aniba simulans Allen (Lauraceae) trunk wood, are shown to derive from two basic structures: 1-allyl-8-hydroxy-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-7-methyl-3-oxobicyclo[3,2,1]octane, substituted by 4-hydroxy, 4-hydroxy-5-methoxy, 4-methoxy or 4,5-dimethoxy groups; and 1-allyl-8-hydroxy-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-7-methyl-4-oxobicyclo[3,2,1]oct-2-ene, substituted by 3-hydroxy or 3-hydroxy-5-methoxy groups. The structural proposals are based on spectral data, interconversions synthesis of a derivative from the known (2R,3S,3aS)-3a-allyl-5-methoxy-2-(3′-methoxy,4′,5′-methylenedioxyphenyl)-3-methyl-2,3,3a,6-tetrahydro-6-oxobenzofuran.