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.     

New 3-hydroxyflavanone (dihydroflavonol) phytoalexins from the papilionate legume Shuteria vestita

Diffusates from the fungus-inoculated leaflets of Shuteria vestita have yielded four novel 3-hydroxyflavanone (dihydroflavonol) phytoalexins. From spectroscopic and chemical evidence, three of these phytoalexins have been identified as (2R,3R,2'R)--3,5,4'-trihydroxy-2'-isopropenyldihydrofurano (4',5'; 6,7) flavanone (shuterol,1), (2R,3R)--3,5,7,4'-tetrahydroxy-6-(3,3-dimethylally) flavanone (shuterin, 2), and (2R,3R,2'R)--3,5,2',4'-tetrahydroxy-2'-isopropenyldihydrofurano (4',5'; 6,7)flavanone (shuterone A, 3). The fourth compound (shuterone B, 4) is considered to be the 2S,3R stereoisomer of shuterone A.     

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.     

Six new isoflavones and a 5-deoxyflavonol glycoside from the leaves of Ateleiaherbert-smithii

Six new isoflavones, 5-methoxy-6,7:3',4'-bis(methylenedioxy)isoflavone (1), 3'-methoxy-6,7:4',5'-bis(methylenedioxy)isoflavone (2), 5,2'-dimethoxy-6,7:4',5'-bis(methylenedioxy)isoflavone (3), 5,3'-dimethoxy-6,7:4',5'-bis(methylenedioxy)isoflavone (4), 5-hydroxy-7,3',4'-trimethoxyisoflavone (5), and 5,6,7,3',4'-pentamethoxyisoflavone (6), were obtained from diethyl ether extracts of the leaves of Ateleia herbert-smithii together with 11 known isoflavones and two chalcones. Four of the isoflavones (1-4) are characterized by a unique bis-methylenedioxyl substitution pattern. A new flavonol glycoside, 5-deoxyisorhamnetin 3-O-alpha-l-rhamnopyranosyl(1' " --> 6' ')-beta-d-glucopyranoside (20), and three known flavonol 3-O-glycosides were obtained from aqueous methanol extracts of leaves of the same species. Spectroscopic methods were used to determine the structures of the compounds. The significance of their occurrence in A. herbert-smithii is discussed from both biosynthetic and taxonomic viewpoints.     

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).     

Two novel flavanones from Greigia sphacelata

As part of our continuing phytochemical investigations of plants from arid environments in Chile, the aerial parts of Greigia sphacelata were examined. Two novel flavanones, 5,7,3'-trihydroxy-6, 4',5'-trimethoxyflavanone (1) and 5,3'-dihydroxy-6,7,4', 5'-tetramethoxyflavanone (2), as well as eight known compounds-1, 3-O-di-trans-p-coumaroylglycerol (3), 1-O-trans-p-coumaroylglycerol (4), a mixture of 1-(omega-feruloyldocosanoyl)glycerol (5) and 1-(omega-feruloyltetracosanoyl)glycerol (6), trans-ferulic acid 22-hydroxydocosanoic acid ester (7), arborinone (8), arborinol (9), and isoarborinol (10)-were isolated.     

Chemical studies on mexican plants used in traditional medicine, VI. Additional new 4-phenylcoumarins from Exostema caribaeum

Six additional 4-phenylcoumarins have been isolated from the MeOH extract of the bark of Exostema caribaeum. Their structures were determined by physical and chemical methods as 4'-5'-dihydroxy-7-methoxy-4-phenyl-5,2'-oxidocoumarin [1], 5,7,4'-trimethoxy-4-phenylcoumarin [2], 5,3'-dihydroxy-7,4'-dimethoxy-4-phenylcoumarin [3], 5-O-beta-D-galactopyranosyl-7,4'-dimethoxy-4-phenylcoumarin [6], 5-O-beta-D-glucopyranosyl-3',4'-dihydroxy-7-methoxy-4-phenylcoumarin+ ++ [7], and 5-O-(6"-acetyl)-beta-D-galactopyranosyl-3', 4'-dihydroxy-7-methoxy-4-phenylcoumarin [9]. The last four compounds are new natural products.     

地椒中1个新的二氢黄酮化合物

研究地椒的化学成分,利用硅胶,ODS,Sephadex LH-20和半制备HPLC等色谱方法分离纯化,结合其MS,NMR,UV,IR和CD等现代分析技术鉴定化合物的结构。从地椒的乙醇提取物乙酸乙酯萃取部位分离并鉴定了4个二氢黄酮化合物,分别为(2S)-5,6-dihydroxy-7,8,4'-trimethoxyflavanone(1),5,4'-dihydroxy-6,7-dimethoxyflavanone(2),(2S)-5,4'-dihydroxy-7,8-dimethoxyflavanone(3),樱花素(4)。其中,化合物1为新化合物,并通过CD谱确定其构型,化合物3为首次分离得到的天然产物,并通过CD谱确定其构型,化合物2为首次从百里香属分离得到,化合物4为首次从地椒中分离得到。体外细胞毒性试验结果表明,化合物1~4对人类肺癌细胞A549具有微弱的细胞毒性,IC₅₀为74.5~135.6μmol·L^-1。     

Biphenyl glycosides from the fruit of Pyracantha fortuneana

Five new biphenyl glycosides, fortuneanosides A (1), B (2), C (3), D (4), and E (5), were isolated from the fruit of Pyracantha fortuneana. Their structures were established as 3,3'-dihydroxy-5'-methoxy-(1,1'-biphenyl)-4-O-beta-d-glucoside, 4'-hydroxy-2,3',5'-trimethoxy-(1,1'-biphenyl)-2'-O-beta-d-glucoside, 4'-hydroxy-3',5'-dimethoxy-(1,1'-biphenyl)-2-O-beta-d-glucoside, 2,4'-dihydroxy-3',5'-dimethoxy-(1,1'-biphenyl)-3-O-beta-d-glucoside, and 3,4'-dihydroxy-3',5'-dimethoxy-(1,1'-biphenyl)-4-O-beta-d-glucoside by spectroscopic analysis. All compounds were evaluated for inhibitory activity against tyrosinase. Compared with arbutin (IC(50) = 0.23 mM), fortuneanoside D possessed more potency, with an IC(50) value of 0.07 mM.     

藏药镰形棘豆中黄酮类化学成分研究

目的：对藏药镰形棘豆Oxytropis falcata的黄酮类化学成分进行研究。方法：通过正相硅胶柱色谱,Sephadex LH-20柱色谱,ODS反相色谱分离﹑纯化,用NMR,MS鉴定结构。结果：从镰形棘豆的氯仿萃取部分分离鉴定了8个黄酮类化合物,分别为2′,4′-二羟基-4-甲氧基查尔酮(1),2′,4′-二羟基查尔酮(2),5,7-二羟基-4′-甲氧基黄酮醇(3),7-羟基-4′-甲氧基二氢黄酮(4),3′,7-二羟基-2′,4′-二甲氧基异黄烷(5),2′-羟基-4′-甲氧基查尔酮(6),2′-甲氧基-4′-羟基查尔酮(7),2′,4′-二羟基二氢查尔酮(8)。结论：这些化合物均为首次从该植物中分离得到。     

思茅豆腐柴中的黄酮类化学成分研究

 目的研究民族药物思茅豆腐柴(Premna szemaoensis Pei)中的黄酮类化学成分。方法利用Sephadex LH-20及硅胶等色谱技术进行分离纯化,根据理化性质、光谱数据进行结构鉴定。结果得到7个黄酮类化合物,分别鉴定为5,4'-二羟基- 3,7,3'-三甲氧基黄酮(1),5-羟基-3',4',6,7-四甲氧基黄酮(2),5,4'-二羟基-7-甲氧基黄酮醇(3),5,3'-二羟基-7,4'-二甲氧基黄酮醇(4),3',4',5-三羟基-3,7-二甲氧基黄酮(5),5,7-二羟基-4'-甲氧基黄酮(6),5-羟基-7,3',4'-三甲氧基黄酮醇(7)。结论这7个化合物均为首次从思茅豆腐柴中分离得到。     

Phytochemistry and preliminary biological evaluation of Cyathostemma argenteum, a malaysian plant used traditionally for the treatment of breast cancer

Bioassay guided fractionation of the roots of Cyathostemma argenteum using the brine shrimp resulted in the isolation of two uncommon flavanones, 2,5-dihydroxy-7-methoxy flavanone 1 and 2,5-dihydroxy-6,7-dimethoxy flavanone 2 while the stem bark yielded the related compounds 5-hydroxy-7-methoxy flavone 3 and 5-hydroxy-6,7-dimethoxy flavone 4. The alkaloids liriodenine 5 and discretamine 6 as well as benzyl benzoate 7 were isolated from the roots and 6 was also isolated from the stembark. In cytotoxicity tests using four human breast cancer cell lines, 1 and 2 were weakly toxic to MCF-7 cells (IC(50) = 19.6 and 19.0 microM, respectively) but showed little activity against MCF-7 cells resistant to doxorubicin or against two oestrogen receptor-deficient cell lines. Compound 5, but not 6 and 7, was moderately cytotoxic against all four cell lines. These results are discussed in the context of the traditional use of C. argenteum in the treatment of breast cancer.     

Chemical studies on Mexican plants used in traditional medicine, III: New 4-phenylcoumarins from Exostema caribaeum

Investigation of the MeOH extract of Exostema caribaeum (Rubiaceae) led to the isolation of three new 4-phenylcoumarins. Their structures, 5-O-beta-D-galactosyl-7-methoxy-3',4'-dihydroxy-4-phenylcoumarin [1a] 7,4',5'-trihydroxy-4-phenyl-5,2'-oxidocoumarin [2a] and 7,4'-dimethoxy-5'-hydroxy-4-phenyl-5,2'-oxido-coumarin [3a] were elucidated by spectral methods and chemical transformations. It was also demonstrated that 4-phenylcoumarins undergo oxidative cyclization under basic conditions in the presence of air to give 4-phenyl-5,2'-oxido-coumarins.     

Isolation of potential cancer chemopreventive agents from Eriodictyon californicum.

Activity-based fractionation of Eriodictyon californicum resulted in the isolation of 12 flavonoids that inhibit the metabolism of the carcinogen benzo[a]pyrene by hamster embryo cells in tissue culture. One was identified as a new flavanone, 3'-methyl-4'-isobutyryleriodictoyol [1], on the basis of spectroscopic analysis and alkaline hydrolysis. The seven other active flavanones were identified as eriodictyol [2], homoeriodictyol [3], 5,4'-dihydroxy-6,7-dimethoxyflavanone [4], pinocembrin [5], sakuranetin [6], 5,7,4'-trihydroxy-6,3'-dimethoxyflavanone [7], and naringenin 4'-methyl ether [8]. Four active flavones were also isolated: cirsimaritin [9], chrysoeriol [10], hispidulin [11], and chrysin [12]. The high inhibition of benzo[a]pyrene metabolism and the activation of benzo[a]pyrene to ultimate carcinogenic DNA-binding metabolites by cirsimaritin and chrysoeriol at a concentration of only 10 micrograms/ml indicates that these flavones warrant further investigation in vivo as potential chemopreventive agents.     

Two auronols from Pseudolarix amabilis.

Two new auronols, amaronols A (1) and B (2), were isolated from the bark of Pseudolarix amabilis, along with pseudolaric acid B (3), pseudolaric acid C (4), demethoxydeacetoxy-pseudolaric acid B (5), pseudolaric acid B-beta-D-glucoside (6), pseudolaric acid A-beta-D-glucoside (7), and myricetin (8). The structures of amaronols A and B were established by spectral data interpretation as 2,4,6-trihydroxy-2-[(3',4',5'-trihydroxyphenyl) methyl]-3(2H)-benzofuranone and 2,4,6-trihydroxy-2-[(3', 5'-dihydroxy-4'-methoxyphenyl) methyl]-3(2H)-benzofuranone, respectively. Antimicrobial testing results of the eight compounds indicated that only pseudolaric acid B was active against Candida albicans (MIC, 3.125 microg/mL; MFC, 6.25 microg/mL), while myricetin was marginally active against Trichophyton mentagrophytes (MIC, 50 microg/mL).     

Terpenylated coumarins as SIRT1 activators isolated from Ailanthus altissima

Four new terpenylated coumarins (1-4) were isolated from the stem bark of Ailanthus altissima by bioactivity-guided fractionation using an in vitro SIRT1 deacetylation assay. Their structures were identified as (2'R,3'R)-7-(2',3'-dihydroxy-3',7'-dimethylocta-6'-enyloxy)-6,8-dimethoxycoumarin (1), 6,8-dimethoxy-7-(3',7'-dimethylocta-2',6'-dienyloxy)coumarin (2), (2'R,3'R,6'R)-7-(2',3'-dihydroxy-6',7'-epoxy-3',7'-dimethyloctaoxy)-6,8-dimethoxycoumarin (3), and (2'R,3'R,4'S,5'S)-6,8-dimethoxy-7-(3',7'-dimethyl-4',5'-epoxy-2'-hydroxyocta-6'-enyloxy)coumarin (4). Compounds 1-4 strongly enhanced SIRT1 activity in an in vitro SIRT1-NAD/NADH assay and an in vivo SIRT1-p53 luciferase assay. These compounds also increased the NAD-to-NADH ratio in HEK293 cells. The present results suggest that terpenylated coumarins from A. altissima have a direct stimulatory effect on SIRT1 deacetylation activity and may serve as lead molecules for the treatment of some age-related disorders.     

Antihyperglycaemic flavonoids from Syzygium samarangense (Blume) Merr. and Perry

2',4'-Dihydroxy-3',5'-dimethyl-6'-methoxychalcone 1, its isomeric flavanone 5-O-methyl-4'-desmethoxymatteucinol 2 and 2'4'-dihydroxy-6'-methoxy-3'-methylchalcone 3 were isolated from the leaves of S. samarangense using a bioassay-directed scheme. In an oral glucose tolerance test, at a dosage of 1.0 mg/20 g mouse, 1 and 2 significantly (alpha = 0.05) lowered the blood glucose levels (BGLs) in glucose-hyperglycaemic mice when administered 15 min after a glucose load. When co-administered with glucose, only 1 showed a significant lowering of BGLs 45 min after its oral administration. When administered 15 min before glucose, none of the flavonoids showed a positive effect. Only 1 decreased significantly, at alpha = 0.05, the BGLs of alloxan-diabetic mice at t = 90-150 min.     

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.     

Potential cncer chemopreventive flavonoids from the stems of Tephrosia toxicaria

A new butenylflavanone, (2S)-5-hydroxy-7-methoxy-8-[(E)-3-oxo-1-butenyl]flavanone (1), and a new rotenoid, 4',5'-dihydro-11,5'-dihydroxy-4'-methoxytephrosin (2), as well as three active flavonoids of previously known structure, isoliquiritigenin (3), genistein (4), and chrysoeriol (5), along with nine known inactive compounds, alpha-toxicarol (6), sumatrol, 6a,12a-dehydro-alpha-toxicarol, 11-hydroxytephrosin, obovatin, marmesin, lupenone, benzyl benzoate, and benzyl trans-cinnamate, were isolated from an ethyl acetate-soluble extract of the stems of Tephrosia toxicaria, using a bioassay based on the induction of quinone reductase (QR) in cultured Hepa 1c1c7 mouse hepatoma cells to monitor chromatographic fractionation. The structures of compounds 1 and 2 were elucidated by spectroscopic data interpretation. All isolates were evaluated for their potential cancer chemopreventive properties utilizing an in vitro assay to determine quinone reductase induction. Selected compounds were tested in a mouse mammary organ culture assay to evaluate the inhibition of 7,12-dimethylbenz[a]anthracene (DMBA)-induced preneoplastic lesions.     

New salicylic acid and isoflavone derivatives from Flemingia paniculata

A new salicylic acid derivative, 2-carboxy-3-(2-hydroxypropanyl)phenol (1), and four new isoflavones, 5,7,4'-trihydroxy-8-(1,1-dimethylprop-2-enyl)isoflavone (2), 5,7,2',4'-tetrahydroxy-8-(1,1-dimethylprop-2-enyl)isoflavone (3), 5,2',4'-trihydroxy-4' ',4' ',5' '(xi)-trimethyl-4' ',5' '-dihydrofurano-(7,6,2' ',3' ')isoflavone (4), and 5,2',4'-trihydroxy-7-(3-methylbut-2-enyloxy)isoflavone (5), were isolated from the stem bark of Flemingia paniculata. The structures of these compounds were established unambiguously by spectroscopic data interpretation. The biogenetic pathways to 1 and 2-4 have been postulated.