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.     

Screening for tyrosinase inhibitors among extracts of seashore plants and identification of potent inhibitors from Garcinia subelliptica

The tyrosinase inhibitory activity of methanol extracts of the leaves of 39 plant species growing on the seashore of Iriomote island (Okinawa, Japan) was investigated. The extracts of Hibiscus tiliaceus, Carex pumila, and Garcinia subelliptica showed potent activity among them. The inhibitors in the extract of Garcinia subelliptica were purified by assay-guided fractionation to give two biflavonoids. These were known compounds (2R,3S-5,7,4',5',7',3',4'-heptahydroxy flavanone[3-8'] flavone and 5,7,4',5',7',3',4'-heptahydroxy[3-8'] biflavanone), although their strong inhibitory activity toward tyrosinase is revealed for the first time in this work. One of these biflavonoids (2R,3S-5,7,4',5',7',3',4'-heptahydroxy flavanone[3-8'] flavone) showed much stronger activity (IC50 2.5 microM) than that of kojic acid (IC50 9.1 microM) when L-tyrosine was used as the substrate.     

Two compounds from allelopathic rice accession and their inhibitory activity on weeds and fungal pathogens

A flavone (5,7,4'-trihydroxy-3',5'-dimethoxyflavone), a cyclohexenone (3-isopropyl-5-acetoxycyclohexene-2-one-1) and a liquid mixture of low polarity, containing long-chain and cyclic hydrocarbons, were isolated from leaves of allelopathic rice accession PI 312777 using column chromatography. Their structures and constituents were identified by means of HR-MS, NMR and GC/MS analyses, respectively. Bioassays showed that both the flavone and cyclohexenone significantly inhibited the growth of weeds Echinochloa crus-galli, Cyperus difformis and Cyperus iris, and the spore germination of fungal pathogens Pyricularia oryzae and Rhizoctonia solani at all tested concentrations. Moreover, the combination of the inactive mixture of low polarity and the active flavone or cyclohexenone significantly enhanced the inhibitory activities on weed growth. In addition, the two compounds and the mixture of low polarity from the leaves of PI312777 did not inhibit the rice growth at the same concentrations. It was also established that both compounds could be released into the soil, and was especially induced by E. crus-galli. The results suggest that 5,7,4'-trihydroxy-3',5'-dimethoxyflavone and 3-isopropyl- 5-acetoxycyclohexene-2-one-1 may act as allelochemicals participating in the defense of rice against weeds and pathogens.     

Flavonoids from Lysidice rhodostegia Hance

A novel flavonoid named mopanolchin (1), together with seven known flavonoids, was isolated by various chromatographic techniques and spectroscopic methods from the EtOAc extract of the roots of Lysidice rhodostegia Hance. The structure of the new compound was elucidated as 1"-(4-hydroxy-3, 5-dimethoxy)phenyl-2"-hydroxymethyl-dioxino [4', 5',1", 2"]mopanol (1) on the basis of spectral analysis.The known compounds were identified as (-)-epicatechin-3-O-gallate (2), epicatechin (3), naringenin (4),eriodictyol (5), luteolin (6), 7, 3', 4'-trihydroxyflavone (7) and (-)-robinetinidol (8).     

Microbial transformation of xanthohumol

Microbial transformation of xanthohumol using the culture broth of Pichia membranifaciens afforded three metabolites, (E)-2"-(2"'-hydroxyisopropyl)-dihydrofurano[2",3":4',3']-2', 4-dihydroxy-6'-methoxychalcone, (2S)-2"-(2"'-hydroxyisopropyl)-dihydrofurano[2",3":7,8]-4'-hydroxy-5-methoxyflavanone and (E)-2"-(2"'-hydroxyisopropyl)-dihydrofurano[2",3":2',3']-4'-hydroxy-5-methoxychalcone.     

Novel synthesis of cholesterol analogs: condensation of pregnenolone with dihydropyran or dihydrofuran.

Pregnenolone 3-(2'-tetrahydropyranyl) ether (1) was condensed with 3,4-[2H]dihydropyran to mainly give (20R)-[6'-(3',4'-[2'H]dihydropyranyl)]-pregn-5-ene-3 beta,20-diol 3-(2'-tetrahydropyranyl) ether (20R-3), according to nuclear magnetic resonance (NMR). Cold, dilute HCl in ethanol removed the tetrahydropyranyl group at C-3 and also opened the dihydropyranyl ring at the C-20 position of 20R-3 to give (20R)-27-norcholest-5-en-22-one-3 beta,20,26-triol (20R-5). Analogous results were obtained by condensing pregnenolone 3-acetate with 3,4-[2H]dihydropyran to provide (20R)-[6'-(3',4'-[2'H]dihydropyranyl)]-pregn-5-ene-3 beta,20-diol 3-acetate (20R-4). Acid-catalyzed opening of the dihydropyranyl ring at C-20 in 20R-4 yielded 20R-7, which, on acetylation followed by crystallization, provided (20R)-27-norcholest-5-en-22-one-3 beta,20,26-triol 3,26-diacetate (20R-8), identical to the diacetate made from 20R-5. Varying the reaction sequence beginning with 20(R,S)-4 gave an 84:16 ratio of 20R to 20S in a mixture of 20(R,S)-8, according to NMR analysis. Crystallization of the mixture from methanol provided pure 20R-8. Condensing 2,3-dihydrofuran and 1 for producing (20R)-[5'-(2',3'-dihydrofuranyl)]-pregn-5-ene-3 beta,20-diol 3-(2'-tetrahydropyranyl) ether (6) gave instead (20R)-26,27-bisnorcholest-5-en-22-one-3 beta,20,25-triol 3-(2'-tetrahydropyranyl) ether (20R-9) by partial hydrolysis during workup. Treating 20R-9 briefly with dilute HCl produced (20R)-26,27-bisnorcholest-5-en-22-one-3 beta,20,25-triol (20R-10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Biflavonoids and a glucopyranoside derivative from Ouratea semiserrata

Two new biflavonoids, 5-hydroxy-7-methoxyflavone-(4' --> O --> 8")-4"',5",7"-trihydroxyflavone and 5-hydroxy-7-methoxyflavone-(4' --> O --> 8")-5",7"-dihydroxy-4"'-methoxyflavone, and the glucopyranoside derivative, 1-O-(4-hydroxyphenyl)-6-O-(4-hydroxybenzoyl)-beta-D-glucopyranoside, as well as the known biflavones lanaraflavone, amentoflavone and podocarpusflavone, the triterpenes lupeol and friedelin, the lignans eudesmin and epieudesmin, the flavonol glycoside rutin, the steroids beta-sitosterol, stigmasterol, 3beta-O-beta-D-glucopyranosylsitosterol, 7-oxostigmast-5-en-3beta-ol and 7-oxostigmasta-5,22-dien-3beta-ol, the carbohydrates alpha- and beta-glucopyranose and 1-O-(4-hydroxybenzoyl)-beta-D-glucopyranoside, and the norsesquiterpene 6,9-dihydroxymegastigma-4,7-dien-3-one, have been isolated from leaves and branches of Ouratea semiserrata. The structures of these compounds were established from spectral data, including two-dimensional NMR experiments and mass spectra.     

Synthesis of some newer derivatives of substituted quinazolinonyl-2-oxo/thiobarbituric acid as potent anticonvulsant agents

5-[1'-[3"-Aminoacetyl-2"-methyl-6",8"-dihalosubstitutedquinazolin-4"(3"H)-onyl]-thiosemicarbazido]-2-oxo/thiobarbituric acids 3a-3h and 5-[2'-amino-5'-[3"-aminomethylene-2"-methyl-6",8"-dihalosubstitutedquinazolin-4"(3"H)-onyl]-1',3',4'-thiadiazol-2'-yl]-2-oxo/thiobarbituric acid 5a-5h were prepared by incorporating 1-[3'-aminoacetyl-2'-methyl-6",8"-dihalosubstituted-quinazolin-4'(3'H)-onyl]-thiosemicarbazides 2a-2d and 2-amino-5-[3'-aminomethylene-2'-methyl-6',8'-dihalosubstituted-quinazolin-4'(3'H)-onyl]-1,3,4-thiadiazoles 4a-4 h respectively at 5(th) position of 2-oxo/thiobarbituric acids (via Mannich reaction). All the newly synthesized compounds were screened for their anti-convulsant activity in MES and PTZ models and were compared with standard drugs phenytoin sodium and sodium valproate. Interestingly, these compounds were found to be devoid of sedative and hypnotic activities when tested. Out of the compounds studied, the most active compound 5h, that is 5-[2'-amino-5'-[3"-aminomethylene-2"-methyl-6",8"-dibromoquinazolin-4"(3"H)-onyl]-1',3',4'-thiadiazol-2'-yl]-2-thiobarbituric acid showed activity (90%) more potent than the standard drug.     

Two isoflavanones from the stem bark of Erythrina sacleuxii

From the stem bark of Erythrina sacleuxii two new isoflavanones, (R)-5,7-dihydroxy-2',4',5'-trimethoxyisoflavanone (trivial name, (R)-2,3-dihydro-7-demethylrobustigenin) and (R)-5-hydroxy-2',4',5'-trimethoxy-2",2"-dimethylpyrano[5",6":6,7]isoflavanone (trivial name, (R)-saclenone) were isolated. In addition the known compounds shinpterocarpin, 2,3-dehydrokievitone, abyssinone V, abyssinone V-4'-methyl ether, erythrinasinate and 4'-O-methylsigmoidin B were isolated. The structures were determined on the basis of spectroscopic evidence.     

Benzofurans and another constituent from seeds of Styrax officinalis

The benzofuran constituents of the seeds of Styrax officinalis were investigated. From the hexane extract, two new constituents named 5-(3"benzoyloxypropyl)-7-methoxy-2-(3',4'-methylenedioxyphenyl)-benzofuran (5) and 4-[3"-(1c-methylbutanoyloxy)propyl]-2-methoxy-(3',4'-methylenedioxyphenyl)-1a, 5b-dihydrobenzo-[3,4]-cyclobutaoxirene (6) were isolated together with four known compounds, 5-[3"-(1c-methylbutanoyloxy)propyl]-7-methoxy-2-(3',4'-dimethoxyphenyl)-benzofuran (4), 5-[3"-(1c-methylbutanoyloxy)propyl]-7- methoxy-2-(3',4'-methylenedioxyphenyl)-benzofuran (3), 5-(3"-acetoxypropyl)-7-methoxy2-(3',4'-methylenedioxphenyl)-benzofuran (2) and 5-(3"-hydroxypropyl)-7-methoxy-2-(3',4'-met hylenedioxyphenyl)-benzofuran (1). Although the compounds 1, 2, and 3 have been isolated previously from the seeds of Styrax obassia, this is the first record of their isolation from seeds of Styrax officinalis. The structures of the isolated compounds were established by 1D- and 2D-NMR (HMBC, HMQC, COSY), FABMS and high-resolution ESI FTMS.     

A benzil and isoflavone derivatives from Derris scandens Benth

A benzil derivative: scandione, 2',2"-dihydroxy-4'-methoxy-4",5"-methylenedioxybenzil and two isoflavones: scandenal, 3'-formyl-4',5-dihydroxy-2",2"-dimethylchromeno-[6,7:5",6"]isoflavone and scanderone, 4',5-dihydroxy-3'-prenyl-2",2"-dimethylchromeno-[7,8:6",5"]isoflavone together with fifteen known compounds were isolated from the stem of D. scandens. Their structures were determined by spectroscopic methods. Radical scavenging, antibacterial and hypertensive activities of some of the compounds were investigated.     

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.     

Flavanone, triterpene and chromene derivatives from the stems of Paramignya griffithii

Five compounds, including three that are novel, were isolated from the stems of Paramignya grifithii (Rutaceae). Two new and one known prenylated flavanones were characterized as 3',4'-dihydroxy-7-methoxy-8-(3-methylbut-2-enyl)-furano(4",5":6,5)-flava-adicin. In addition, a triterpene, 3-oxo-tirucalla-7,24-diene-21-al, and a novel chromene, 6-(2-hydroxyethyl)-2,2-dimethyl-2H-1-benzopyran, were identified.     

Systematic synthesis of four epicatechin series procyanidin trimers and their inhibitory activity on the Maillard reaction and antioxidant activity

A systematic synthesis of four natural epicatechin series procyanidin trimers [[4,8:4",8"]-2,3-cis-3,4-trans: 2",3"-cis-3",4"-trans: 2,3-trans-(-)-epi-catechin-(-)-epicatechin-(+)-catechin, [4,8:4",8"]-2,3-cis-3,4-trans: 2",3"-cis-3",4"-trans: 2,3-cis-tri-(-)-epicatechin: procyanidin C1, [4,8:4",8"]-2,3-cis-3,4-trans: 2",3"-trans-3",4"-trans: 2,3-trans-(-)-epicatechin-(+)-catechin-(+)-catechin: procyanidin C4, and [4,8:4",8"]-2,3-cis-3,4-trans: 2",3"-trans-3",4"-trans: 2,3-cis-(-)-epicatechin-(+)-catechin-(-)-epicatechin] is described. Condensation of (2R,3R,4S)-5,7,3'4'-tetra-O-benzyl-4-(2"-ethoxyethyloxy)flavan derived from (-)-epicatechin as an electrophile with the dimeric nucleophiles in the presence of TMSOTf followed by deprotection yielded trimers. Inhibitory activities on the Maillard reaction and antioxidant activity on lipid peroxide of the synthesized oligomers were also investigated.     

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.     

(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.     

Carotenoids with a 5,6-dihydro-5,6-dihydroxy-beta-end group, from yellow sweet potato "Benimasari", Ipomoea batatas Lam

A series of carotenoids with a 5,6-dihydro-5,6-dihydroxy-beta-end group, named ipomoeaxanthins A (1), B (2), C1 (3) and C2 (4) were isolated from the flesh of yellow sweet potato "Benimasari", Ipomoea batatas Lam. Their structures were determined to be (5R,6S,3'R)-5,6-dihydro-beta,beta-carotene-5,6,3'-triol (1), (5R,6S,5'R,6'S)-5,6,5',6'-tetrahydro-beta,beta-carotene-5,6,5'6'-tetrol (2), (5R,6S,5'R,8'R)-5',8'-epoxy-5,6,5',8'-tetrahydro-beta,beta-carotene-5,6-diol (3), and (5R,6S,5'R,8'S)-5',8'-epoxy-5,6,5',8'-tetrahydro-beta,beta-carotene-5,6-diol (4) by UV-Vis, NMR, MS and CD data.     

阿勃小麦缺体及其细胞学研究

通过阿勃单体自交分离缺体其频率为0.03—5.75%,缺体结实率0—81.65%,所获18个缺体系平均结实率31.24%。在减数分裂中,1B、1D、2A、2D、4B、4D、5A、6A、6B、6D、7A和7B缺体有90%以上的细胞为2n=20",1.65—10.00%的细胞为2n=19"+2',自交后代96%以上为缺体;5D、1A和3A缺体分别有97.55%、16.67%、10.28%的细胞为2n=19"+2',5B、3D和3B缺体除了分别有92.55%、26.98%、25.58%的细胞为2n=19"+2'外,还有少数细胞游离4个至更多的单价体,但这些缺体系自交后代的缺体株率仍为90%左右。     

The Chemical Constituents in Dacrydium pierrei

Nine compounds are isolated from the leaves and branches of Dacrydiurn pierrei Hickle for the first time. Comparison of physico-chemical data were assayed by means of spectrometry chemical analysis. They are identified as sotetsuflavone (1), amentoflavone-4', 4'", 7, 7"-tetramethyl-ether (2), trans-communic acid (3), 19- hydroxy-totarol (4), 12-methoxy-dehydro-abietic acid (5), (+) phyllocladene (6), daucosterol(7), β-sitosterol (8), and n-tetratriacontanol (9).