Flavonoids from the stem bark of Bolusanthus speciosus

Three flavonoids (bolusanthols A-C), viz an isoflavan and two prenylated isoflavanones, were isolated from the stem bark of Bolusanthus speciosus in addition to four known flavonoids, 5,7,3'-trihydroxy-4'-methoxy-5'-methoxy-gamma,gamma-dimethylallylisoflavanone, 5,7,2'-trihydroxy-4'-methoxy-6,5'-di(gamma,gamma)-dimethylallyl)isoflavanone, 3,5,7,3',4'-pentahydroxy-6-gamma,gamma-dimethylallylflavone and 5,7,2',4'-tetrahydroxy-8,3'-di(gamma,gamma-dimethylallyl)-isoflavanone. The structure of the new compounds were determined to be 4,2',3',4'-tetrahydroxy-6,7-methylenedioxyisoflavan (bolusanthol A), 5,7,3',4'-tetrahydroxy-5'-gamma,gamma-dimethylallylisoflavanone (bolusanthol B), and 5,7,4'-trihydroxy-6,3'-di(gamma,gamma-dimethylallyl)isoflavanone (bolusanthol C) by spectroscopic methods.     

Antimicrobial and radical scavenging flavonoids from the stem wood of Erythrina latissima

From the stem wood of Erythrina latissima, two isoflavones and a flavanone were isolated and characterized as 7,3'-dihydroxy-4'-methoxy-5'-(gamma,gamma-dimethylallyl)isoflavone (erylatissin A), 7,3'-dihydroxy-6',6'-dimethyl-4',5'-dehydropyrano [2',3': 4',5']isoflavone (erylatissin B), (-)-7,3'-dihydroxy-4'-methoxy-5'-(gamma,gamma-dimethylallyl)flavanone (erylatissin C), respectively, in addition to 10 known flavonoids. Structures of these compounds were determined on the basis of their spectroscopic data. These compounds showed antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Candida mycoderma. The isolated compounds also exhibited weak radical scavenging properties towards DPPH radical.     

膜荚黄芪中两个新的抗菌异黄烷化合物

膜荚黄芪（Astragalus membranaceus (Fisch.)Bunge）为豆科植物,其根入药,有补气固表、利尿脱毒、敛疮疤生肌、益气补中之功效,主要用于气虚乏力、食少便溏、中气下陷、久泻脱肛、便血崩漏、表虚自汗、气虚     

Studies on the late steps of (+) pisatin biosynthesis: evidence for (-) enantiomeric intermediates

Pisatin, a 6a-hydroxyl-pterocarpan phytoalexin from pea (Pisum sativum L.), is relatively unique among naturally occurring pterocarpans by virtue of the (+) stereochemistry of its 6a-11a C-C bond. However, pisatin synthesizing pea tissue has an isoflavone reductase, first identified in alfalfa, which acts on the (-) antipode. In order to establish the natural biosynthetic pathway to (+) pisatin, and to evaluate the possible involvement of intermediates with a (-) chirality in its biosynthesis, we administered chiral, tritium-labeled, isoflavanones and pterocarpans to pisatin-synthesizing pea cotyledons and compared the efficiency of their incorporation. Pea incorporated the isoflavanone, (-) sophorol, more efficiently than either its (+) antipode, or the pterocarpans (+) or (-) maackiain. (-) Sophorol was also metabolized by protein extracts from pisatin-synthesizing pea seedlings in a NADPH-dependent manner. Three products were produced. One was the isoflavene (7,2'-dihydroxy-4',5'-methylenedioxyisoflav-3-ene), and another had properties consistent with the isoflavanol (7,2'-dihydroxy-4',5'-methylenedioxyisoflavanol), the expected product for an isoflavanone reductase. A cDNA encoding sophorol reductase was also isolated from a cDNA library made from pisatin-synthesizing pea. The cloned recombinant sophorol reductase preferred (-) sophorol over (+) sophorol as a substrate and produced 7,2'-dihydroxy-4',5'-methylenedioxyisoflavanol. Although no other intermediates in (+) pisatin biosynthesis were identified, the results lend additional support to the involvement of intermediates of (-) chirality in (+) pisatin synthesis.     

Flavones and isoflavones from the west African Fabaceae Erythrina vogelii

The CH(2)Cl(2)/MeOH extract of the stem bark of Erythrina vogelii (Fabaceae) from Nigeria has yielded two novel isoflavones, 7,4'-dihydroxy-8-(gamma,gamma-dimethylallyl)-2'zeta-(4'-hydroxyisopropyl)dihydrofurano[1',3':5,6]isoflavone (vogelin H) (1) and 7,4'-dihydroxy-8-[(2'zeta,3'-dihydroxy-3'-methyl)butyl]-2',2'-dimethyl-3',4'-dehydropyrano[1',4':5,6]isoflavone (vogelin I) (2), a novel flavone, 7,4'-dihydroxy-2',2'-dimethyl-3',4'-dehydropyrano[1',4':5,6]flavone (vogelin J) (3), and eight known flavonoids.     

Flavones and phenylpropenoids in the surface exudate of Psiadia punctulata

Three flavones, 5,7-dihydroxy-2',3',4',5'-tetramethoxyflavone, 5,4'-dihydroxy-7,2',3',5'-tetramethoxyflavone, and 5,7,4'-trihydroxy-2',3',5'-trimethoxyflavone were isolated from the leaf exudate of Psiadia punctulata, together with the previously reported 5-hydroxy-7,2',3',4',5'-pentamethoxyflavone and 5,7,3'-trihydroxy-2',4',5'-trimethoxyflavone. The two phenylpropenoids, Z-docosyl-p-coumarate and E-docosyl-p-coumarate were also isolated. The structures were determined on the basis of spectroscopic evidence.     

C-methylated and C-prenylated isoflavonoids from root extract of Desmodium uncinatum

A pterocarpan, 1,9-dihydroxy-3-methoxy-2-methylpterocarpan (named uncinacarpan) and two isoflavanones, 5,7-dihydroxy-2',3',4'-trimethoxy-6-(3-methylbut-2-enyl)isoflavanone (named uncinanone D) and 5,4'-dihydroxy-7,2'-dimethoxy-6-methylisoflavanone (named uncinanone E), were isolated from the CH(2)Cl(2) root extract of Desmodium uncinatum (Jacq.) DC and characterised by spectroscopic methods. In addition, a rare pterocarpan edudiol and two known abietane diterpenes, 7-oxo-15-hydroxydehydroabietic acid and 7-hydroxycallitrisic acid were identified. The fraction of the root extract that was analysed induced germination of Striga hermonthica seeds, but none of the isolated compounds showed this activity.     

Isoflavanones from the allelopathic aqueous root exudate of Desmodium uncinatum

Three isoflavanones, 5,7,2',4'-tetrahydroxy-6-(3-methylbut-2-enyl)isoflavanone (1), 4",5"-dihydro-5,2',4'-trihydroxy-5"-isopropenylfurano-(2",3";7,6)-isoflavanone (2) and 4",5"-dihydro-2'-methoxy-5,4'-dihydroxy-5"-isopropenylfurano-(2",3";7,6)-isoflavanone (3) and a previously known isoflavone 5,7,4'-trihydroxyisoflavone [genistein (4)] were isolated and characterised spectroscopically from the root exudate of the legume Desmodium uncinatum (Jacq.) DC. We propose the names uncinanone A, B, and C for compounds 1, 2 and 3, respectively. Isolated fractions containing uncinanone B (2) induced germination of seeds from the parasitic weed Striga hermonthica (Del.) Benth. and fractions containing uncinanone C (3) moderately inhibited radical growth, the first example of a newly identified potential allelopathic mechanism to prevent S. hermonthica parasitism.     

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.     

Different antibacterial actions of isoflavones isolated from Erythrina poeppigiana against methicillin-resistant Staphylococcus aureus

AIMS: To screen six isoflavones isolated from Erythrina poeppigiana (Leguminosae) for their antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). METHODS AND RESULTS: Stem bark of E. poeppigiana was macerated with acetone and the methylene chloride-soluble fraction of the residue was applied to repeated silica gel column chromatography and eluted. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by a broth dilution method. Inactive compounds that failed inhibiting bacterial growth at 25 microg ml(-1) were further investigated for their combination effects with methicillin and oxacillin. Of the isolated isoflavones, 5,7,4'-trihydroxy-8,3'-di(gamma,gamma-dimethylallyl)isoflavone (isolupalbigenin) exhibited the highest anti-MRSA activity (MICs: 1.56-3.13 microg ml(-1); MBCs: 6.25-12.5 microg ml(-1)), followed by 5,7,4'-trihydroxy-6-gamma,gamma-dimethylallylisoflavone (erythrinin B). Inactive compounds were combined with methicillin or oxacillin, 5,4'-dihydroxy-(3',4'-dihydro-3'-hydroxy)-2',2'-dimethylpyrano[5',6':6,7]isoflavone (M-Wi-2) intensifying the susceptibility of MRSA strains to these antibiotics. In all but one strain, the MIC values of methicillin were reduced from > or =100 to 6.25-12.5 microg ml(-1) in the presence of M-Wi-2 (25 microg ml(-1)). CONCLUSIONS: Isoflavones from E. poeppigiana showed two different antibacterial activities against MRSA: direct growth inhibition and intensification of methicillin sensitivity. SIGNIFICANCE AND IMPACT OF THE STUDY: Isolupalbigenin and M-Wi-2 could lead to the development of compounds for new approaches against MRSA infection.     

Antimicrobial and antioxidant flavonoids from the root wood of Bolusanthus speciosus

Three new flavonoids-5,7,4'-trihydroxy-6-[1-hydroxy-2-methylbuten-2-yl]isoflavone (isogancaonin C), 7,2'-dihydroxy-4'-methoxyisoflav-3-ene (bolusanthin III), 6,6'-dihydroxy-4'-methoxy-2-arylbenzofuran (bolusanthin IV), in addition to eight known flavonoids; derrone, medicarpan, genistein, wighteone, lupiwighteone, gancaonin C, 7-hydroxy-4'-methoxyisoflavone and 7,3'-dihydroxy-4'-methoxyisoflavone were isolated from the root wood of Bolusanthus speciosus. The compounds showed strong antimicrobial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Candida mycoderma. The isolated compounds also showed moderate to strong radical scavenging properties against DPPH radical with the highest activities shown by the 2-arylbenzofuran, the isoflav-3-ene and 7,3'-dihydroxy-4'-methoxyisoflavone in decreasing order.     

On-line identification of the constituents of Buyang Huanwu decoction in pig serum using combined HPLC-DAD-MS techniques

Buyang Huanwu decoction (BYHWD) is a widely used Chinese traditional compound medicine that has proved effective in treating cerebrovascular illnesses; however, its active substances have remained unknown. In this paper, serum chemistry and combined high-performance liquid chromatography (HPLC), photodiode-array detection and mass-spectrometry techniques were used to study the constituents of BYHWD from pig serum after oral administration. A total of 45 characteristic HPLC peaks were detected from serum containing drug. The chemical structures of nine of the peaks were tentatively elucidated as 7,3'-dihydroxy-4'-methoxyisoflavone-7-O-glucuronide (P1), 7-hydroxy-4'-methoxyisoflavone-7-O-glucuronide (P2), 7,2',4'-trihydroxy-3'-methoxyisoflavane-7-O-sulphate (P3), 3-hydroxy-9,10-dimethoxypterocarpan-3-O-glucuronide (P4), 7,2'-dihydroxy-3',4'-dimethoxyisoflavane-7-O-glucuronide (P5), 3-hydroxy-9,10-dimethoxypterocarpane-3-O-sulphate (P6), 4(1H)-quinolinone (P7 or P8), 4-hydroxyquinoline (P8 or P7) and oleic acid (P9). All of the identified peaks, with the exception of P9, were metabolites of the constituents of BYHWD in vivo.     

Prenylated flavonoids from Moghania philippinensis

Five prenylated flavonoids, 8-(1,1-dimethylallyl)genistein (1), 5,7,3',4'-tetrahydroxy-2',5'-di(3-methylbut-2-enyl)isoflavone (2), 5,7,3'-trihydroxy-2'-(3-methylbut-2-enyl)-4',5'-(3,3-dimethylpyrano)isoflavone (3), (2R)-5,2',4'-trihydroxy-8,5'-di(3-methylbut-2-enyl)-6,7-(3,3-dimethylpyrano)flavanone (4a) and (2S)-5, 2', 4'-trihydroxy-8,5'-di(3-methylbut-2-enyl)-6,7-(3,3-dimethylpyrano)flavanone (4b), were isolated from the roots of Moghania philippinensis. The structures of these compounds were determined on the basis of spectroscopic and chemical means.     

Efficient production and capture of 8-prenylnaringenin and leachianone G-biosynthetic intermediates of sophoraflavanone G--by the addition of cork tissue to cell suspension cultures of Sophora flavescens

It has previously been demonstrated that the addition of cork tissue to cell suspension cultures of Sophora flavescens stimulates the production of sophoraflavanone G, most of which has been recovered from the added cork tissue. In the present study, it was found that two precursors of sophoraflavanone G, 8-prenylnaringenin (sophoraflavanone B) and leachianone G, both of which have never been detected either in cultured cells or in the original plants, also accumulated in the added cork tissue. Thirteen minor flavonoids including three prenylated flavonoids, in addition to 8-prenylnaringenin and leachianone G, were isolated from the cork tissue co-incubated with S. flavescens cells. The new compounds flavescenones A, B and C, were determined to be (3R)-5, 7, 2'-trihydroxy-6-gamma, gamma-dimethylallyl-4', 5'-methylenedioxyisoflavanone; 5, 7, 2'-trihydroxy-6-gamma, gamma-dimethylallyl-4', 5'-methylenedioxyisoflavone and 2-[2',4'-dihydroxy-3'-(gamma-hydroxymethyl-gamma-methylallyl)phenyl]-5,6-methylenedioxybenzofuran, respectively, by means of spectroscopic analyses that included 2D-NMR techniques.     

Antioxidant lignans from Larrea tridentata

Three lignans, (7S,8S,7'S,8'S)-3,3',4'-trihydroxy-4-methoxy-7,7'-epoxylignan, meso-(rel 7S,8S,7'R,8'R)-3,4,3',4'-tetrahydroxy-7,7'-epoxylignan, and (E)-4,4'-dihydroxy-7,7'-dioxolign-8(8')-ene, together with 10 known compounds, were isolated from the leaves of Larrea tridentata. The structures of the new compounds were determined primarily from 1D and 2D NMR spectroscopic analysis. Their antioxidant activities against intracellular reactive oxygen species were evaluated in HL-60 cells.     

5-Hydroxy-seco-carotenoids from Pittosporum tobira

Three 5-hydroxy-seco-carotenoids were isolated from seeds of Pittosporum tobira. These structures were determined to be (3S,3'S,5'?)-3,3'-di(tetradecanoyloxy)-5'-hydroxy-5,6,5',6'-diseco-beta,beta-carotene-5,6,6'-trione (1), (3S,5?,3'S,5'R,6'S,9'Z)-3-tetradecanoyloxy-5',6'-epoxy-5,3'-dihydroxy-5',6'-dihydro-5,6-seco-beta,beta-caroten-6-one (2), and (3S,5?,3'S,5'R,6'R)-3-tetradecanoyloxy-5,3',5'-trihydroxy-6',7'-didehydro-5',6'-dihydro-5,6-seco-beta,beta-caroten-6-one (3) based on analysis of UV-vis, IR, FAB MS, and NMR spectroscopic data.     

Inactivation of pea genes by RNAi supports the involvement of two similar O-methyltransferases in the biosynthesis of (+)-pisatin and of chiral intermediates with a configuration opposite that found in (+)-pisatin

(+)-Pisatin, the major phytoalexin of pea (Pisum sativum L.), is believed to be synthesized via two chiral intermediates, (-)-7,2'-dihydroxy-4',5'-methylenedioxyisoflavanone [(-)-sophorol] and (-)-7,2'-dihydroxy-4',5'-methylenedioxyisoflavanol [(-)-DMDI]; both have an opposite C-3 absolute configuration to that found at C-6a in (+)-pisatin. The expression of isoflavone reductase (IFR), which converts 7,2'-dihydroxy-4',5'-methylenedioxyisoflavone (DMD) to (-)-sophorol, sophorol reductase (SOR), which converts (-)-sophorol to (-)-DMDI, and hydroxymaackiain-3-O-methyltransferase (HMM), believed to be the last step of (+)-pisatin biosynthesis, were inactivated by RNA-mediated genetic interference (RNAi) in pea hairy roots. Some hairy root lines containing RNAi constructs of IFR and SOR accumulated DMD or (-)-sophorol, respectively, and were deficient in (+)-pisatin biosynthesis supporting the involvement of chiral intermediates with a configuration opposite to that found in (+)-pisatin in the biosynthesis of (+)-pisatin. Pea proteins also converted (-)-DMDI to an achiral isoflavene suggesting that an isoflavene might be the intermediate through which the configuration is changed to that found in (+)-pisatin. Hairy roots containing RNAi constructs of HMM also were deficient in (+)-pisatin biosynthesis, but did not accumulate (+)-6a-hydroxymaackiain, the proposed precursor to (+)-pisatin. Instead, 2,7,4'-trihydroxyisoflavanone (TIF), daidzein, isoformononetin, and liquiritigenin accumulated. HMM has a high amino acid similarity to hydroxyisoflavanone-4'-O-methyltransferase (HI4'OMT), an enzyme that methylates TIF, an early intermediate in the isoflavonoid pathway. The accumulation of these four compounds is consistent with the blockage of the synthesis of (+)-pisatin at the HI4'OMT catalyzed step resulting in the accumulation of liquiritigenin and TIF and the diversion of the pathway to produce daidzein and isoformononetin, compounds not normally made by pea. Previous results have identified two highly similar "HMMs" in pea. The current results suggest that both of these O-methyltransferases are involved in (+)-pisatin biosynthesis and that one functions early in the pathway as HI4'OMT and the second acts at the terminal step of the pathway.     

Synthesis and anthelmintic activity of 7-substituted 3,4a-dimethyl-4a,5a,8a,8b-tetrahydro-6H-pyrrolo[3',4':4,5]furo[3,2-b]pyridine-6,8(7H)-diones

The racemic 7-substituted 3,4a-dimethyl-4a,5a,8a,8b-tetrahydro-6H-pyrrolo[3',4':4,5]furo[3,2-b]pyridine-6,8(7H)-diones represent novel tricyclic compounds with strong in vivo efficacy against the parasitic nematode Haemonchus contortus Rudolphi in sheep. Here we report on the synthesis of tricyclic endo-2,3-dihydro[3,2-b]pyridine-type cycloadducts and describe the separation of the racemic 3,4a-dimethyl-7-ethyl-4a,5a,8a,8b-tetrahydro-6H-pyrrolo[3',4':4,5]furo[3,2]pyridine-6,8(7H)-dione into the enantiomers by HPLC. The absolute configuration of the most anthelmintically active (4aS,5aS,8aS,8bR)-enantiomer was determined by single crystal X-ray analysis using its stable (4aS,5aS,8aS,8bR)-enantiomer-CuCl2 (2:1)-complex.     

Prolyl endopeptidase inhibitors from Syzygium samarangense (Blume) Merr. & L. M. Perry

Compounds isolated from the hexane extract of the leaves of Syzygium samarangense (Blume) Merr. & L. M. Perry were tested for inhibitory activity against the following serine proteases: trypsin, thrombin and prolyl endopeptidase. The compounds were identified as an intractable mixture of alpha-carotene and beta-carotene (1), lupeol (2), betulin (3), epi-betulinic acid (4), 2',4'-dihydroxy-6'-methoxy-3'-methylchalcone (5), 2'-hydroxy-4',6'-dimethoxy-3'-methylchalcone (6), 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (7), 2',4'-dihydroxy-6'-methoxy-3'-methyldihydrochalcone (8) and 7-hydroxy-5-methoxy-6,8-dimethylflavanone (9). Hydrogenation of compounds 5, 6 and 7 yielded compound 8, 2'-hydroxy-4',6'-dimethoxy-3'-methyldihydrochalcone (10) and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethyldihydrochalcone (11), respectively. The hydrogenated products of compounds 6 and 7 were also tested for enzyme inhibitory activity. In addition, beta-sitosterol (12) and beta-D-sitosterylglucoside (13) were also isolated. This is the first report of the isolation of compounds 1-6, 8 and 13 from this plant. Compounds 3-8 and 10 exhibited significant and selective inhibition against prolyl endopeptidase among three serine proteases. This is the first report of this kind of activity for all these compounds.     

(Rel)-1beta,2alpha-di-(2,4-dihydroxy-6-methoxybenzoyl)-3beta, 4alpha-di-(4-methoxyphenyl)-cyclobutane and other flavonoids from the aerial parts of Goniothalamus gardneri and Goniothalamus thwaitesii

The aerial parts of Goniothalamus gardneri (Annonaceae) has yielded the known flavonoids 2'-hydroxy-4,4',6'-trimethoxychalcone (flavokawain A), 2',4'-dihydroxy-4,6'-dimethoxydihydrochalcone, 4,2',4'-trihydroxy-6'-methoxydihydrochalcone, 5,7,4'-trimethoxyflavanone (naringenin trimethyl ether) and 7-hydroxy-5,4'-dimethoxyflavanone (tsugafolin) together with three novel compounds, the dimer characterised as (rel)-1beta,2alpha-di-(2,4-dihydroxy-6-methoxybenzoyl)-3beta,4alpha-di-(4-methoxyphenyl)-cyclobutane, 2',4'-dihydroxy-4,6'-dimethoxychalcone and 2'-hydroxy-4,4',6'-trimethoxydihydrochalcone. The last two have previously been synthesised but appear to be new natural products. A similar study of the aerial parts of G. thwaitesii led only to the isolation of the known flavonoids myricetin 4'-O-methyl ether-3-O-alpha-L-rhamnopyranoside (mearnsitrin) and myricetin-3-O-methyl ether (annulatin), together with the triterpenes friedelinol, friedelin and betulinic acid. All compounds were identified by spectroscopic analysis and, for known compounds, by comparison with published data.