Geranins A and B, new antiprotozoal A-type proanthocyanidins from Geranium niveum.

Bioassay-guided fractionation of the antiprotozoal extract of Geranium niveum led to the isolation of two new A-type proanthocyanidins, epi-afzelechin-(4beta-->8, 2beta-->O-->7)-afzelechin (1) and epi-catechin-(4beta-->8, 2beta-->O-->7)-afzelechin (2). Compounds 1 and 2 were given the trivial names of geranins A and B, respectively. In addition, five known compounds, mahuannin B (3), reynoutrin (4), hyperin (5), methyl gallate (6), and 3-beta-caffeoyl-12-oleanen-28-oic acid (7), were obtained. The structures of the new proanthocyanidins were elucidated by spectroscopic and chemical methods as well as CD measurements. Compounds 1, 2, and 4-7 were tested against axenically grown trophozoites of Giardia lamblia and Entamoeba histolytica.     

Immunomodulatory proanthocyanidins from Ecdysanthera utilis

Two new A-type proanthocyanidins have been isolated from Ecdysanthera utilis and identified as epicatechin-(4beta-->8,2beta-->O-->7)-epicatechin-(4beta-->8)-epicatechin (5) and epicatechin-(4beta-->8)-epicatechin-(4beta-->8,2beta-->O-->7)-epicatechin-(4beta-->8)-epicatechin (6), respectively. The structure-related components epicatechin (1), procyanidin B2 (2), proanthocyanidin A1 (3), proanthocyanidin A2 (4), and aesculitannin C (7) were also isolated. All of these compounds were identified and evaluated for immunopharmacological activity. Human peripheral blood mononuclear cells (PBMC) were used as target cells, and cell proliferation was determined by (3)H-thymidine uptake. The results indicated that compound 3 suppressed PBMC proliferation activated with phytohemagglutinin (PHA). The inhibitory mechanisms may involve the blocking of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) production, since compound 3 attenuated IL-2 and IFN-gamma production of PBMC in a dose-dependent manner. Therefore, it is suggested that immunomodulatory agents are present in E. utilis.     

A-Type proanthocyanidin trimers from cranberry that inhibit adherence of uropathogenic P-fimbriated Escherichia coli

Three proanthocyanidin trimers possessing A-type interflavanoid linkages, epicatechin-(4beta-->6)-epicatechin-(4beta-->8, 2beta-->O-->7)-epicatechin (4), epicatechin-(4beta-->8, 2beta-->O-->7)-epicatechin-(4beta-->8)-epicatechin (5), and epicatechin-(4beta-->8)-epicatechin-(4beta-->8, 2beta-->O-->7)-epicatechin (6), were isolated from the ripe fruits of Vaccinium macrocarpon (cranberry) and prevented adherence of P-fimbriated Escherichia coli isolates from the urinary tract to cellular surfaces containing alpha-Gal(1-->4)beta-Gal receptor sequences similar to those on uroepithelial cells. The structure of 4 was elucidated by a combination of spectroscopic methods and acid-catalyzed degradation with phloroglucinol. Also isolated were the weakly active epicatechin-(4beta-->8, 2beta-->O-->7)-epicatechin (procyanidin A2) (3) and the inactive monomer epicatechin (1) and the inactive dimer epicatechin-(4beta-->8)-epicatechin (procyanidin B2) (2).     

New furofuran and butyrolactone lignans with antioxidant activity from the stem bark of Styrax japonica

A new furofuran lignan, styraxlignolide B (1), and four new dibenzyl-gamma-butyrolactone lignans, styraxlignolides C-F (2-5), were isolated from the EtOAc-soluble fraction of stem bark of Styrax japonica. Known compounds, taraxerol (6), syringin (7), and (-)-pinoresinol glucoside (8), were also obtained. The structures of styraxligonolides B-F were determined as 2alpha-(4'-hydroxy-3'-methoxyphenyl)-6alpha-(3' ',4' '-methylenedioxyphenyl)-8-oxo-3,7-dioxabicyclo[3.3.0]octane 4'-O-(beta-D-glucopyranoside) (1), (2S,3S)-2alpha-(3' '-hydroxy-4' '-methoxybenzyl)-3beta-(4'-hydroxy-3'-methoxybenzyl)-gamma-butyrolactone 4'-O-(beta-D-glucopyranoside) (2), (2S,3S)-2alpha-(4' '-hydroxy-3' '-methoxybenzyl)-3beta-(4'-hydroxy-3'-methoxybenzyl)-gamma-butyrolactone 4'-O-(beta-D-glucopyranoside) (3), (2S,3S)-2alpha-(4' '-hydroxy-3' '-methoxybenzyl)-3beta-(4'-hydroxy-3'-methoxybenzyl)-gamma-butyrolactone 4' '-O-(beta-D-glucopyranoside) (4), and (2S,3S)-2alpha-(3' ',4' '-dimethoxybenzyl)-3beta-(4'-hydroxy-3'-methoxybenzyl)-gamma-butyrolactone 4'-O-(beta-D-glucopyranoside) (5) by spectroscopic means including 2D NMR. Compounds 1-8 were tested in vitro for antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. Styraxlignolide C (2), styraxlignolide D (3), styraxlignolide E (4), and (-)-pinoresinol glucoside (8) exhibited weak radical-scavenging activity in the DPPH assay, with IC50 values of 380, 278, 194, and 260 microM, respectively.     

Neolignans, a coumarinolignan, lignan derivatives, and a chromene: anti-inflammatory constituents from Zanthoxylum avicennae

Eight new compounds, including four new neolignans, (7' S,8' S)-bilagrewin ( 1), (7' S,8' S)-5-demethoxybilagrewin ( 2), (7' S,8' S)-5- O-demethyl-4'- O-methylbilagrewin ( 3), and (7' S,8' S)-nocomtal ( 4), a new coumarinolignan, (7' S,8' S)-4'- O-methylcleomiscosin D ( 5), two new lignan derivatives, (+)-9'- O-( Z)-feruloyl-5,5'-dimethoxylariciresinol ( 6) and (+)-9'- O-( E)-feruloyl-5,5'-dimethoxylariciresinol ( 7), and a new chromene, ( E)-3-(2,2-dimethyl-2 H-chromen-6-yl)prop-2-enal ( 8), have been isolated from the stem wood of Zanthoxylum avicennae, together with 18 known compounds ( 9- 26). The structures of these new compounds were determined through spectroscopic and MS analyses. (7' S,8' S)-4'- O-Methylcleomiscosin D ( 5), cleomiscosin D ( 9), skimmianine ( 18), robustine ( 19), and integrifoliolin ( 23) exhibited inhibition (IC 50 < or = 18.19 microM) of superoxide anion generation by human neutrophils in response to formyl- l-methionyl- l-leucyl- l-phenylalanine/cytochalasin B (FMLP/CB). In addition, skimmianine ( 18) inhibited FMLP/CB-induced elastase release with an IC 50 value of 19.15 +/- 0.66 microM.     

New neolignans that inhibit DNA polymerase beta lyase

Bioassay-directed fractionation of a methyl ethyl ketone extract of the roots of Endlicheria aff. resulted in the isolation of four new neolignans (1-4) and eight known compounds, namely, canellin A (5), canellin C (6), 3'-methoxyguianin (7), (7S,8R,1'S,5'S,6'R)-Delta(2',8')-3',6'-dihydroxy-5'-methoxy-3,4-methylenedioxy-4'-oxo-8.1',7.5'-neolignan (8), armenin-B (9), dillapiole (10), 1-allyl-2,6-dimethoxy-3,4-methylenedioxybenzene (11), and omega-hydroxyisodillapiole (12). The structures of the new compounds (1-4) were established as (7S,8R,1'S,5'S,6'R)-Delta(2',8')-5',6'-dihydroxy-3'-methoxy-3,4-methylenedioxy-4'-oxo-8.1',7.5'-neolignan, (7S,8R,1'S,5'S,6'R)-Delta(2',8')-3',5',6'-trihydroxy-3,4-methylenedioxy-4'-oxo-8.1',7.5'-neolignan, 2,4-dimethoxy-5,6-methylenedioxy-1-(2-propenyl)benzene, and 2,6-dimethoxy-3,4-methylenedioxycinnamyl alcohol, respectively, on the basis of spectroscopic interpretation.     

Prenylated flavanones with anti-tyrosinase activity from Dalea boliviana

Three new prenylated flavanones, (2S)-5,7,2'-trihydroxy-5'-(1',1'-dimethylallyl)-8-prenylflavanone (1), (2S)-5,7,2'-trihydroxy-8,3'-diprenylflavanone (2), and (2S)-5,2'-dihydroxy-6',6'-dimethylchromeno-(7,8:2',3')-3'-prenylflavanone (3), and a known chromeno (dimethylpyrano) flavanone, obovatin (4), were isolated from the n-hexane extract of Dalea boliviana roots. The compounds were evaluated in vitro in relation to their inhibitory effect on the tyrosinase activity by using a spectrophotometric method.     

Aromatase inhibitors from Broussonetia papyrifera.

Bioassay-guided fractionation of an ethyl acetate-soluble extract from the whole plants of Broussonetia papyrifera, using an in vitro aromatase inhibition assay, led to the isolation of five new active compounds, 5,7,2',4'-tetrahydroxy-3-geranylflavone (1), isogemichalcone C (8), 3'-[gamma-hydroxymethyl-(E)-gamma-methylallyl]-2,4,2',4'-tetrahydroxychalcone 11'-O-coumarate (9), demethylmoracin I (10), and (2S)-2',4'-dihydroxy-2' '-(1-hydroxy-1-methylethyl)dihydrofuro[2,3-h]flavanone (11), and 10 known (12-21) compounds which were also found to be active. Of these compounds, the most potent were 9 (IC(50) 0.5 microM), 11 (IC(50) 0.1 microM), isolicoflavonol (12, IC(50) 0.1 microM), and (2S)-abyssinone II (13, IC(50) 0.4 microM). Additionally, six new compounds, 5,7,3',4'-tetrahydroxy-6-geranylflavonol (2), 5,7,3',4'-tetrahydroxy-3-methoxy-6-geranylflavone (3), (2S)-7,4'-dihydroxy-3'-prenylflavan (4), 1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)propane (5), 1-(2,4-dihydroxy-3-prenylphenyl)-3-(4-hydroxyphenyl)propane (6), and 1-(4-hydroxy-2-methoxyphenyl)-3-(4-hydroxy-3-prenylphenyl)propane (7), were isolated and characterized, but proved to be inactive as aromatase inhibitors, as were an additional 21 known compounds. The structures of the new compounds (1-11) were elucidated by spectroscopic methods. Structure-activity relationships in the aromatase assay were determined for the benzofurans, biphenylpropanoids, coumarins, and various types of flavonoids (chalcones, flavans, flavanones, and flavones) obtained among a total of 42 constituents of B. papyrifera.     

New phenolic constituents from Smilax bracteata

From the methanol extract of Smilax bracteata rhizomes, six new phenolic compounds, (2S,3S)-5-O-beta-D-glucopyranosyloxy-6-methyl-3'-methoxy-3,7,3'-trihydroxyflavan (1), (2S,3S)-5-O-beta-D-glucopyranosyloxy-6-methyl-4'-methoxy-3,7,4'-trihydroxyflavan (2), 3beta-(3',5'-dihydroxyphenyl)-2alpha-(4' '-hydroxyphenyl)dihydrobenzofuran-5-carbaldehyde (3), (1-p-O-coumaroyl-6-O-feruroyl)-beta-D-fructofuranosyl-alpha-D-glucopyranoside (4), (1-p-O-coumaroyl-3,6-di-O-feruroyl)-beta-D-fructofuranosyl-alpha-D-glucopyranoside (5), and (6-O-feruroyl)-beta-D-fructofuranosyl-(6-O-acetyl)-alpha-D-glucopyranoside (6) were isolated together with five known compounds. Their structures were established by spectral data interpretation.     

Lignan glycosides from Neoalsomitra integrifoliola

Five new lignan glycosides, (8R*,7' S*,8' R*)-5,5'-dimethoxy-7-oxolariciresinol 9'-O-beta-D-xylopyranoside (1), (7S,8R)-dihydrodehydrodiconiferyl alcohol 9-O-beta-D-apiofuranosyl-(1-->6)-O-beta-D-glucopyranoside (2), (7S*,8R*,7' S*,8' R*)-4,4'-dimethoxyhuazhongilexin 9-O-beta-D-xylopyranoside (4), (7S*,8R*,7' S*,8' R*)-4,4'-dimethoxyhuazhongilexin 9-O-alpha-L-arabinopyranoside (5), and (7S*,8R*,7' S*,8' R*)-huazhongilexin 9-O-(2-feruloyl)-beta-D-xylopyranoside (6), together with four known compounds, (7R,8S)-dihydrodehydrodiconiferyl alcohol 9-O-beta-D-glucopyranoside (3), the 9-O-beta-D-xylopyranoside of icariol A(2) (7), huazhongilexin (8), and nudiposide (9), were isolated from the leaves of Neoalsomitra integrifoliola. Their structures were determined by spectroscopic analysis and chemical methods. Compounds 2, 3, 8, and 9 showed weak anti-inflammatory activities.     

Constituents of the bark and twigs of Artocarpus dadah with cyclooxygenase inhibitory activity

Fractionation of an ethyl acetate-soluble extract of the bark of Artocarpus dadah has led to the isolation of three new prenylated stilbenoid derivatives, 3-(gamma,gamma-dimethylallyl)resveratrol (1), 5-(gamma,gamma-dimethylallyl)oxyresveratrol (2), 3-(2,3-dihydroxy-3-methylbutyl)resveratrol (3), and a new benzofuran derivative, 3-(gamma,gamma-dimethylpropenyl)moracin M (4), along with six known compounds, oxyresveratrol, (+)-catechin, afzelechin-3-O-alpha-L-rhamnopyranoside, (-)-epiafzelechin, dihydromorin, and epiafzelechin-(4beta-->8)-epicatechin. From an ethyl acetate-soluble extract of the twigs of the same plant were isolated compound 4 and two new neolignan derivatives, dadahols A (5) and B (6), as well as 10 known compounds, oxyresveratrol, (+)-catechin, afzelechin-3-O-alpha-L-rhamnopyranoside, resveratrol, steppogenin, moracin M, isogemichalcone B, gemichalcone B, norartocarpetin, and engeletin. The structures of compounds 1-6 were determined using spectroscopic and chemical methods. Isolates were evaluated for their inhibitory effects against both cyclooxygenase-1 (COX-1) and -2 (COX-2) and in a mouse mammary organ culture assay.     

Inhibitory effects on HIV-1 protease of constituents from the wood of Xanthoceras sorbifolia

From a methanolic extract of the wood of Xanthoceras sorbifolia, two new compounds, 29-hydroxy-3-oxotirucalla-7,24-dien-21-oic acid (3, xanthocerasic acid) and epigallocatechin-(4beta-->8, 2beta-->O-7)-epicatechin (6), were isolated, together with 11 known compounds. Of the isolated compounds, 3-oxotirucalla-7, 24-dien-21-oic acid (2), oleanolic acid (4), and 6 were found to be inhibitory substances against human immunodeficiency virus (HIV-1) protease, with their 50% inhibitory concentrations (IC(50)) being 20, 10, and 70 microg/mL, respectively. Condensed tannins of high molecular weights with epicatechin and epiafzelechin as the main extender units were found to be the most active principles of this plant (IC(50) values ca. 6.0 microg/mL).     

New cyanogenic and alkyl glycoside constituents from Phyllagathis rotundifolia

Methanolic extracts of the leaves, stems, and roots of Phyllagathis rotundifolia collected in Malaysia yielded seven galloylated cyanogenic glucosides based on prunasin, with six of these being new compounds, prunasin 2',6'-di-O-gallate (3), prunasin 3',6'-di-O-gallate (4), prunasin 4',6'-di-O-gallate (5), prunasin 2',3',6'-tri-O-gallate (6), prunasin 3',4',6'-tri-O-gallate (7), and prunasin 2',3',4',6'-tetra-O-gallate (8). Also obtained was a new alkyl glycoside, oct-1-en-3-yl alpha-arabinofuranosyl-(1-->6)-beta-glucopyranoside (9). For compounds 3-8, the galloyl groups were individually linked to the sugar moieties via ester bonds. All new structures were established on the basis of NMR and MS spectroscopic studies. In addition, prunasin (1), gallic acid and its methyl ester, beta-glucogallin, 3,6-di-O-galloyl-D-glucose, 1,2,3,6-tetra-O-galloyl-beta-D-glucose, strictinin, 6-O-galloyl-2,3-O-(S)-hexahydroxydiphenoyl-D-glucose, praecoxin B, and pterocarinin C were isolated and identified. The isolation of 1 and its galloyl derivatives (3-8) from a Melastomataceous plant are described for the first time.     

Bioactive secondary metabolites from Boesenbergia pandurata of Myanmar and their preferential cytotoxicity against human pancreatic cancer PANC-1 cell line in nutrient-deprived medium

The chloroform extract of rhizomes of Boesenbergia pandurata demonstrated marked preferential cytotoxicity against human pancreatic PANC-1 cancer cells in nutrient-deprived medium. Bioactivity-directed investigation of this extract yielded four new secondary metabolites, geranyl-2,4-dihydroxy-6-phenethylbenzoate ( 1), 2',4'-dihydroxy-3'-(1'-geranyl)-6'-methoxychalcone ( 2), (1' R,2' S,6' R)-2-hydroxyisopanduratin A ( 3), and (2 R)-8-geranylpinostrobin ( 4), and twenty known compounds ( 5- 24). Among the known compounds, (2 S)-6-geranylpinostrobin ( 5), (+/-)-6-methoxypanduratin A ( 6), and (2 S)-7,8-dihydro-5-hydroxy-2-methyl-2-(4'-methyl-3'-pentenyl)-8-phenyl-2 H,6 H-benzo[1,2- b:5,4- b']dipyran-6-one ( 7) were isolated for the first time from a natural source. The structures of these compounds were elucidated using extensive spectroscopic techniques including CD measurements. All the isolated compounds showed varying degrees of in vitro preferential cytotoxicity against PANC-1 cells. Nicolaioidesin B ( 11) and panduratin A ( 17) were most potent, each showing a PC 100 at 2.5 microM.     

Phenolic glycosides from berries of Pimenta dioica

Four new phenolic glycosides, (2-hydroxy-3-methoxy-5-allyl)phenyl beta- d-(6-O-E-sinapoyl)glucopyranoside (1), (1' R,5' R)-5-(5-carboxymethyl-2-oxocyclopentyl)-3 Z-pentenyl beta-D-(6-O-galloyl)glucopyranoside (2), (S)-alpha-terpinyl [alpha-L-(2-O-galloyl)arabinofuranosyl]-(1-->6)-beta-D-glucopyranoside (3), and (R)-alpha-terpinyl [alpha-L-(2-O-galloyl)arabinofuranosyl]-(1-->6)-beta-D-glucopyranoside (4), were isolated from the berries of Pimenta dioica together with eight known flavonoids. The structures of 1-4 were elucidated on the basis of MS and NMR data and enzymatic hydrolysis. All four glycosides showed radical-scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals.     

苍耳子中苯丙素类化学成分的研究

目的 研究菊科植物苍耳(Xanthium sibiricum Patrin ex Widder)的干燥成熟带总苞的果实(苍耳子)中苯丙素类化学成分。方法 采用正相硅胶柱色谱、反相十八烷基硅烷键合硅胶(ODS)柱色谱、Sephadex LH-20凝胶柱色谱和半制备高效液相色谱(HPLC)等色谱方法进行分离纯化,并结合高分辨质谱(HR-ESI-MS)、核磁共振(NMR)对分离得到的化合物进行结构鉴定。采用脂多糖(LPS)诱导的巨噬细胞RAW 264.7为筛选模型评价分离得到化合物的抗炎活性。结果 从苍耳子体积分数95%乙醇提取物的乙酸乙酯萃取物中分离并鉴定了24个苯丙素类化合物,分别为c-藜芦酰乙二醇(1)、3,4'-二羟基-3'-甲氧基苯丙酮(2)、阿魏醛(3)、丁香脂素(4)、蛇菰宁(5)、落叶松脂醇(6)、愈创木基甘油(7)、3-hydroxy-l-(4-hydroxy-3,5-dimethoxyphenyl)-1-propanone(8)、salicifoliol(9)、6-(4-hydroxy-3-methoxyphenyl)-3,7-dioxabicyclo[3.3.0]octan-2-ol(10)、榕醛(11)、jatrointelignan D(12)、icariol A₂(13)、异落叶松脂素(14)、ehletianol C(15)、(7R,7'R,7”S,7‴S,8S,8'S,8”S,8‴S)-4”,4‴-dihydroxy-3,3',3”,3‴,5,5'-hexamethoxy-7,9';7',9-diepoxy-4,8”;4',8‴-bisoxy-8,8'-dineolignan-7”,7‴,9”,9‴-tetraol(16)、(7R,7'R,7”R,7‴S,8S,8'S,8”S,8‴S)-4”,4‴-dihydroxy-3,3',3”,3‴,5,5'-hexamethoxy-7,9';7',9-diepoxy-4,8”;4',8‴-bisoxy-8,8'-dineolignan-7”,7‴,9”,9‴-tetraol(17)、2-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)-propan-1,3-diol(18)、2,3-bis-(4-hydroxy-3-methoxyphenyl)-3-methoxypropanol(19)、楝叶吴萸素B(20)、threo-guaiacylglycerol-8-vanillin ether(21)、erythro-guaiacylglycerol-8-vanillin ether(22)、黄花菜木脂素B(23)和27-对香豆酰氧基熊果酸(24)。结论 化合物6~24为首次从苍耳中分离得到。对分离得到的24个化合物进行抗炎活性筛选,其中,化合物14、21和23具有抗炎活性,其IC₅₀值分别为(28.14±1.89),(16.78±0.68)和(38.42±2.15)μmol·L^-1。     

Structures of carotenoids with 5,6-dihydro-beta-end groups from the spindle shell Fusinus perplexus

A series of pirardixanthin derivatives, 1, 2, 3, 4, and 5, possessing the 5,6-dihydro-beta-end group were isolated from the spindle shell Fusinus perplexus.(1,2) Their structures and absolute configurations were determined by modern spectroscopic analysis to be (4S,5S,6S,4'S,5'S,6'S)-5,6,5',6'-tetrahydro-beta,beta-carotene-4,4'-diol (1), (3S,4R,5S,6S,4'S,5'S,6'S)-5,6,5',6'-tetrahydro-beta,beta-carotene-3,4,4'-triol (2), (3S,4R,5S,6S,3'S,4'R,5'S,6'S)-5,6,5',6'-tetrahydro-beta,beta-carotene-3,4,3',4'-tetrol (3), (5S,6S,4'S,5'S,6'S)-4'-hydroxy-5,6,5',6'-tetrahydro-beta,beta-caroten-4-one (4), and (4'S,5'S,6'S)-4'-hydroxy-5',6'-dihydro-beta,beta-caroten-4-one (5).     

Prenylated flavonoids from the heartwood of Artocarpus communis with inhibitory activity on lipopolysaccharide-induced nitric oxide production

A new prenylated chalcone, 3' ',3' '-dimethylpyrano[3',4']2,4,2'-trihydroxychalcone (1), was isolated from the heartwood of Artocarpus communis. Two flavonoid derivatives, (-)-cycloartocarpin (9) and (-)-cudraflavone A (10), were isolated as new isomers. In addition, eight known flavonoids, isobacachalcone (2), morachalcone A (3), gemichalcones B (4) and C (5), artocarpin (6), cudraflavone C (7), licoflavone C (8), and (2S)-euchrenone a(7) (11), were isolated and identified from this plant for the first time. Compounds 1-4, 6, and 11 exhibited potent inhibitory activity on nitric oxide production in RAW264.7 LPS-activated mouse macrophage cells with IC(50) values of 18.8, 6.4, 16.4, 9.3, 18.7, and 12.3 microM, respectively. The structure of compound 1 was elucidated by spectroscopic data analysis, including 1D and 2D NMR experiments.     

New bioactive flavonoids and stilbenes in cubé resin insecticide

Fractionation of cubé resin from Lonchocarpus utilus and L. urucu roots led to the isolation and identification of 11 minor flavonoids and stilbenes containing the gem-dimethylpyran moiety or a dihydrodiol derivative thereof. The eight new compounds were as follows: the isoflavonoid cis-4',5'-dihydro-4',5' '-dihydroxylonchocarpusone (2); four (2S)-6-(gamma, gamma-dimethylallyl)-6',6'-dimethylpyran[2',3':7, 8]flavanones with substituents of 5-hydroxy-3',4'-dimethoxy (3), 5, 3'-dihydroxy-4'-methoxy (4), 5,4'-dihydroxy-3'-methoxy (5), and 3', 4'-dimethoxy (6); and three 6',6'-dimethylpyran[2',3':3', 4']stilbenes with 4-hydroxy-5'-methoxy (9), 3,5'-dimethoxy-4-hydroxy (10) and 3,4,5-trimethoxy (11) substitution patterns. Structure-activity relationships for inhibition of NADH:ubiquinone oxidoreductase activity (bovine heart electron transport particles) and phorbol ester-induced ornithine decarboxylase activity (cultured MCF-7 cells) generally parallel those for cytotoxicity (MCF-7 and Hepa 1clc7 cells).     

20S proteasome inhibitory activity of flavonoids isolated from Spatholobus suberectus

The promising biological role of the ubiquitin proteasome pathway (UPP) in cancer therapy has recently emerged. Inhibition of proteasome has been proposed as a new therapeutic target for treatment of cancer. Bioassay‐guided fractionation of a MeOH extract of the stems of Spatholobus suberectus resulted in seven compounds, liquiritigenin (1), isoliquiritigenin (2), genistein (3), daidzein (4), medicarpin (5), 7‐hydroxyflavanone (6) and formononetin (7), which were evaluated for the first time for their inhibitory effect on 20S proteasome. Among the isolated compounds, 2, 3 and 6 exhibited inhibitory activities on human 20S proteasome with IC₅₀ values of 4.88 ± 1.5, 9.26 ± 1.2 and 5.21 ± 1.5 µm , respectively. Copyright © 2010 John Wiley & Sons, Ltd.