Characterization of a novel (±)-abscisic acid metabolite

By application of (±)-abscisic acid and (±)-[1-¹⁴C]-abscisic acid to pea seedlings ( Pisum sativum L. cv. Kleine Rheinländerin), a new abscisic acid metabolite (Pisumic acid, PISA) could be isolated and structurally characterized by combined gas chromatography-mass spectrometry. From data of exact mass determination, it is suggested that the metabolite has the tentative structure of 4'-dihydroabscisic acid with a hydroxylated methyl group at C-6'. That this could be evidence for an alternative pathway of abscisic acid metabolism which was suggested earlier by Walton et al. [Planta 112: 87–90 (1973)] is discussed.     

Formation of the depurinating N3adenine and N7guanine adducts by reaction of DNA with hexestrol-3',4'-quinone or enzyme-activated 3'-hydroxyhexestrol. Implications for a unifying mechanism of tumor initiation by natural and synthetic estrogens

The nonsteroidal synthetic estrogen hexestrol (HES), which is diethylstilbestrol hydrogenated at the C-3-C-4 double bond, is carcinogenic. Its major metabolite is the catechol, 3'-OH-HES, which can be metabolically converted to the catechol quinone, HES-3',4'-Q. Study of HES was undertaken with the scope to substantiate evidence that natural catechol estrogen-3,4-quinones are endogenous carcinogenic metabolites. HES-3',4'-Q was previously shown to react with deoxyguanosine to form the depurinating adduct 3'-OH-HES-6'-N7Gua by 1,4-Michael addition [Jan S-T, Devanesan PD, Stack DE, Ramanathan R, Byun J, Gross ML, et al. Metabolic activation and formation of DNAadducts of hexestrol,a synthetic nonsteroidal carcinogenic estrogen. Chem Res Toxicol 1998;11:412-9.]. We report here formation of the depurinating adduct 3'-OH-HES-6'-N3Ade by reaction of HES-3',4'-Q with Ade by 1,4-Michael addition. The structure of the N3Ade adduct was established by NMR and MS. We also report here formation of the depurinating 3'-OH-HES-6'-N7Gua and 3'-OH-HES-6'-N3Ade adducts by reaction of HES-3',4'-Q with DNA or by activation of 3'-OH-HES by tyrosinase, lactoperoxidase, prostaglandin H synthase or 3-methylcholanthrene-induced rat liver microsomes in the presence of DNA. The N3Ade adduct was released instantaneously from DNA, whereas the N7Gua adduct was released with a half-life of approximately 3 h. Much lower (<1%) levels of unidentified stable adducts were detected in the DNA from these reactions. These results are similar to those obtained by reaction of endogenous catechol estrogen-3,4-quinones with DNA. The similarities extend to the instantaneously-depurinating N3Ade adducts and relatively slowly-depurinating N7Gua adducts. The endogenous estrogens, estrone and estradiol, their 4-catechol estrogens and HES are carcinogenic in the kidney of Syrian golden hamsters. These results suggest that estrone (estradiol)-3,4-quinones and HES-3',4'-Q are the ultimate carcinogenic metabolites of the natural and synthetic estrogens, respectively. Reaction of the electrophilic quinones by 1,4-Michael addition with DNA at the nucleophilic N-3 of Ade and N-7 of Gua is suggested to be the major critical step in tumor initiation by these compounds.     

Studies on Chemical Compositions of Podocarpus neriifolius D. Don

Eleven compositions isolated from Podocarpus neriifolius D. Don were identified as n-C34H69OH (1), β-sitosteryl stearate (2), β-sitosterol (3), sciadopitysin (8), podocarpusflavone B (12), robustaflavone-7"-methyl ether (13), podocarpusflavone A(14), robustaflavone (15), p-hydroxyl benzoic acid (16), 2"-O-rhamnosylscopariu (23), 2"-O-rhamnosyl vitexin (24) on the basis of physical constants and spectral data. Among them, compound 8, 13 and 15 were found from the species for the first time. Compound 113 and 24 were reported from Podocarpaceae for the first time. The ethanol extract of P.neriitolius showed obvious cytotoxicity against A-549 and HT-29.     

A New Isoflavonoid from Belamcanda chinensis （L.） DC.

A new isoflavonoid, 5, 6, 7, 3＇-terahydroxy-8, 4＇, 5＇-trimethoxyisoflavone （1）, along with 10 known isoflavonoids, namely 5, 6, 7, 4＇-tetrahydroxy-8-methoxyisoflavone （2）, irilone （3）, genistein （4）, tectorigenin （5）, irigenin （6）, irisflorentin （7）, dichotomitin （8）, dimethyltectorigenin （9）, iridin （10）, and tectoridin （11）, was isolated from the alcohol extract of the rhizomes of Belamcanda chinensis （L.） DC. The structures of these compounds were elucidated on the basis of results of spectroscopic analysis.     

一株嗜碱放线菌发酵液 中的抗肿瘤活性成分(英文)

从嗜碱放线菌YIM 80149的发酵液中分离得到4个抗肿瘤活性成分.根据波谱数据,鉴定为4',7-dihydroxyisoflavone(1)、4',5,7-trihydroxyflavone(2)、3-(4-hydroxy-3-methoxyphenyl)-2(E)-propenoic acid(3)、2-methoxy-1,4-naphthoquinone(4).     

Molecular regulation of catechins biosynthesis in tea [Camellia sinensis (L.) O. Kuntze

Catechins are bioprospecting molecules present in tea and any effort towards metabolic engineering of this important moiety would require knowledge on gene regulation. These are synthesized through the activities of phenylpropanoid and flavonoid pathways. Expression regulation of various genes of these pathways namely phenylalanine ammonia-lyase (CsPAL), cinnamate 4-hydroxylase (CsC4H), p-coumarate:CoA ligase (Cs4CL), flavanone 3-hydroxylase (CsF3H), dihydroflavonol 4-reductase (CsDFR) and anthocyanidin reductase (CsANR) was accomplished previously. In depth analyses of the remaining genes namely, chalcone synthase (CsCHS), chalcone isomerase (CsCHI), flavonoid 3'5'-hydroxylase (CsF3'5'H) and anthocyanidin synthase (CsANS) were lacking. The objective of the work was to clone and analyze these genes so as to generate a comprehensive knowledge on the critical genes of catechins biosynthesis pathway. Gene expression analysis was carried out in response to leaf age and external cues (drought stress, abscisic acid, gibberellic acid treatments and wounding). A holistic analysis suggested that CsCHI, CsF3H, CsDFR, CsANS and CsANR were amongst the critical regulatory genes in regulating catechins content.     

Iridoid glucosides and flavones from the aerial parts of Avicennia marina

Two new iridoid glucosides, namely, 2'-O-[(2E,4E)-5-phenylpenta-2,4-dienoyl]mussaenosidic acid (1; mussaenosidic acid = [1S-(1alpha,4aalpha,7alpha,7aalpha)]-1-(beta-D-glucopyranosyloxy)-1,4a,5,6,7,7a-hexahydro-7-hydroxy-7-methylcyclopenta[c]pyran-4-carboxylic acid) and 2'-O-(4-methoxycinnamoyl)mussaenosidic acid (2), were isolated from the aerial parts of the mangrove plant Avicennia marina. Beside that, one known iridoid glucoside, 2'-O-coumaroylmussaenosidic acid (3) and four known flavones (flavone = 2-phenyl-4H-1-benzopyran-4-one) including 4',5-dihydroxy-3',7-dimethoxyflavone (4), 4',5-dihydroxy-3',5',7-trimethoxyflavone (5), 4',5,7-trihydroxyflavone (6), and 3',4',5-trihydroxy-7-methoxyflavone (7) were also isolated and identified. The structures of these compounds were elucidated by NMR spectroscopy and by low- and high-resolution mass spectrometry. The chemotaxonomic significance of these findings was discussed. In addition, each isolated compound was evaluated for the ability of alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity.     

Production of 4-hydroxybutyric acid by metabolically engineered Mannheimia succiniciproducens and its conversion to γ-butyrolactone by acid treatment

γ-Butyrolactone (GBL) is an important four carbon (C4) chemical, which has a wide range of industrial applications. GBL can be produced by acid treatment of 4-hydroxybutyric acid (4-HB), which is a derivative of succinic acid. Heterologous metabolic pathways were designed and established in succinic acid overproducing Mannheimia succiniciproducens LPK7 (ldhA pflD pta ackA mutant) by the introduction of heterologous genes that encode succinyl-CoA synthetase, CoA-dependent succinate semialdehyde dehydrogenase, and either 4-hydroxybutyrate dehydrogenase in LPK7 (p3S4CD) or succinate semialdehyde reductase in LPK7 (p3SYCD). Fed-batch cultures of LPK7 (p3S4CD) and LPK7 (p3SYCD) resulted in the production of 6.37 and 6.34 g/L of 4-HB (molar yields of 0.143 and 0.139), respectively. Finally, GBL was produced by acid treatment of the 4-HB obtained from the fermentation broth with molar yield of 0.673. This study demonstrates that 4-HB, and potentially other four carbon platform chemicals, can be produced by the engineered rumen bacterium M. succiniciproducens.     

Flavonoids, including an unusual flavonoid-Mg2+ salt, from roots of Cudrania cochinchinensis

Four flavonoids with 2',4'-di-oxygenated B-rings, cochinchinol A (1), cochinchinol B (2), (2R,3R)-4',7-dihydroxy-2',5-dimethoxydihydroflavonol (3), 4',7-dihydroxy-2',5-dimethoxyflavonol (4), along with 11 known compounds, were isolated from an ethanolic extract of the roots of Cudrania cochinchinensis. Their structures were elucidated by chemical and spectroscopic methods. Cochinchinol A (1) and cochinchinol B (2) have two hitherto unprecedented flavonol salt structures in natural product chemistry. Cytotoxic activities were evaluated against several different cell lines.     

Non-covalent interaction of 2', 4', 5', 7'-tetrabromo-4, 5, 6, 7-tetrachlorofluorescein with proteins and its application

The interactions of 2', 4', 5', 7'-tetrabromo-4, 5, 6, 7-tetrachlorofluorescein (TBTCF) with BSA, ovalbumin (OVA) and poly-L-lysine (PLYS) at pH 3.70 have been investigated by combination of the spectral correction technique and the Langmuir isothermal adsorption. The active connection actions such as ion pairs, van der Waals' force, hydrogen bond, hydrophobic bond were proposed to explain the non-covalent interaction between TBTCF and BSA, OVA and PLYS. Effects of the electrolyte and high temperature indicated that union of the active connections between TBTCF and BSA and OVA was too firm to be destroyed. The relationship between the binding number of TBTCF and variety fraction of the amino acid residues was analyzed. The binding number of TBTCF depended on the number of positively charged amino acid residues. The other amino acid residues surrounded and seized TBTCF by hydrogen bonds and hydrophobic bonds when the electrostatic attraction pulled TBTCF to link protein. In addition, a novel method named the absorbance ratio difference was established for determination of protein in trace level and was applied with much higher sensitivity than the ordinary method.     

Synthesis of aminooxy-functionalized lanthanide(III) chelates for carbonyl-group conjugation

The syntheses of three new aminooxy-tethered lanthanide(III) chelates, compounds 1-3, incorporating DOTA (= 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), DTPA (= diethylenetriaminepentaacetic acid), or a substituted terpyridine (2,2',2',2'-[2,2': 6',2'-terpyridine-6,6'-diylbis(methylenenitrilo)]tetraacetic acid), respectively, are described. Reagents 1-3 can be used for carbonyl 'labeling', as shown by the formation of the corresponding oxime-ether bioconjugates of naltrexone (16) and 2-deoxy-beta-D-glucose (17) (Scheme 4).     

地菍的化学成分(英文)

为了研究野牡丹科药用植物地菍(Melastoma dodecandrum)的化学成分,采用柱层析方法分离鉴定了15个化合物,通过波谱分析及对比文献等方法鉴定为4-O-β-D-吡喃葡萄糖基-3,3',4'-三甲氧基鞣花酸(1),槲皮素3-O-刺槐二糖苷(2),8-C-吡喃葡萄糖基-5,7,3',4'-四羟基黄酮(3),3-O-β-D-吡喃葡萄糖基-4',5,7-三羟基黄酮(4),6-C-吡喃葡萄糖基-4',5,7-三羟基黄酮(5),3-hydroxy-22(29)-hopen-23-oic acid(6),2,3-dihydroxy-9(11)-fernen-23-oic acid(7),3β-sitosterol laminaribioside(8),姜糖酯B(9),3-O-β-D-galactopyranoside-glycerol1-alkanoates(10),胡萝卜苷(11),β-谷甾醇(12),二十八烷醇(13),二十四烷酸(14)以及三十四烷(15)化合物结构。所有化合物均为首次从该植物中分离得到。     

枇杷果肉有机酸组分及有机酸在果实内的分布

用高效离子交换色谱（HPIC）测定了枇杷（Eriobotrya japonica Lindk）18个品种（小毛枇杷、夹脚、卓南1号、解放钟、富阳、森尾早生、华宝2号、香钟10号、白花、土肥、多宝2号、乌躬白、洛阳青、茂木、早钟6号、白梨、塘头4号和长红3号）的成熟果肉和2个品种（解放钟和早钟6号果）成熟果实不同组织有机酸含量。结果表明,成熟果肉中均含有苹果酸、奎尼酸、柠檬酸、异柠檬酸、α-酮戊二酸、富马酸、草酰乙酸、酒石酸8种有机酸,有的还含有微量的阿魏酸、顺乌头酸和B一香豆酸。大多数品种果肉中苹果酸含量最高,平均含量为4399mg kg^-1 FW,占总酸的62．7％;其次是奎尼酸,其平均含量为2042mgkg—FW,占总酸的29．1％。品种之间可滴定酸和有机酸含量差异很大。通过对果肉可滴定酸进行聚类分析,可把18个枇杷品种分为五个组群：极高酸（小毛枇杷）、高酸（夹脚、卓南1号、解放钟和富阳）、中酸（森尾早生、华宝2号、香钟10号、白花、土肥和多宝2号）、低酸（乌躬白、洛阳青、茂木和早钟6号）和极低酸（白梨、塘头4号和长红3号）。解放钟和早钟6号果肉和果皮的总酸含量及可滴定酸均无显著差异,但果皮和果肉的总酸含量和可滴定酸均大大高于种子。相似于果肉,果皮和种子的主要有机酸也是苹果酸和奎尼酸。果皮中苹果酸含量远高于奎尼酸,但种子中苹果酸含量比奎尼酸稍低。此外,种子中苹果酸和奎尼酸比果肉和果皮中的低得多。     

A New Stilbene from Cercis chinensis Bunge

To study new natural products, we used ODS （YMC, Kyoto, Japan） and silica gel column chromatography to separate compounds in Cercis chinensis Bunge （Leguminosae）. A new stilbene, trans- 3, 5, 3＇, 4＇-tetrahydroxy-4-methylstilbene （1）, along with 10 known compounds, namely piceatannol （2）, dihydromyricetin （3）, catechin （4）, dihydrorobinetin （5）, menisdaurin （6）, lithospermoside （7）, teatannin （8）, dasycarponin （9）, β-sitosterol （10）, and daucosterin （11）, was isolated from C. chinensis. Their structures were elucidated on the basis of spectroscopic evidence. Compounds 2-6 and 9 were isolated from the genus Cercis Linn. for the first time.     

高效启动子在微生物生产4-羟基丁酸中的应用

4-羟基丁酸(4HB)是一种精神类药物,还可用于合成聚-4-羟基丁酸酯(P4HB)、聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P3HB4HB)等聚合物。在醇脱氢酶(DhaT)和醛脱氢酶(AldD)的共同作用下,1,4-丁二醇(BD)可转化为4-羟基丁酸。通过引入T7和PRe两种高效启动子,加强了dhaT和aldD基因的表达,促进合成4-羟基丁酸的反应进行。同时还研究了底物1,4-丁二醇的浓度对4HB生产的影响。结果表明:提供10 g/L的1,4-丁二醇,受PRe启动子调控的重组菌A.hydrophila 4AK4(pZQ01)可生产6.00 g/L的4-羟基丁酸,比对照组提高43.20%;而受T7启动子调控的重组菌A.hydrophila 4AK4(pZQ04)可生产4.87 g/L 4-羟基丁酸,比对照组提高16.23%。意味着T7和PRe这两种启动子确实发挥了提高基因表达水平的作用,加速了4-羟基丁酸的生物合成。     

Isolation and characterization of a meta-cleavage product in the degradation of quinaldic acid by Azotobacter sp.

Abstract From different samples of soil seventeen strains were isolated which grew aerobically in mineral salts medium with quinaldic acid as sole carbon source. Mutants were induced with N -methyl- N '-nitro- N -nitrosoguanidine. One mutant could be isolated which accumulated a yellow compound. The properties of this purified compound were those expected for 2-oxo-3-(4'-hydroxy-2'-oxo-3',4'-en-butyrate)-pyridine-6-carboxylic acid.     

A model system for the study of heteroexchange diffusion: Methotrexate-folate interactions in L1210 leukemia and Ehrlich ascites tumor cells

A unique interaction between the folate analog, methotrexate (4-amino-4-deoxy-10-methylpteroylglutamic acid), and the naturally occurring folates in L1210 leukemia and Ehrlich ascites tumor cells provides a useful model for the study of heteroexchange diffusion. The presence of intracellular binding sites with a high affinity for methotrexate but a low affinity for folic acid and its tetrahydrofolate derivatives permit the measurement of true unidirectional influx rates for methotrexate and assure that the trans-stimulation of methotrexate uptake by the intracellular presence of the other folates is due solely to a primary augmentation of this carrier influx mechanism. Further, since free methotrexate does not appear prior to saturation of the binding sites, the reaction between the folates and carrier at the inner cell membrane is undisturbed by methotrexate released from carrier as the complex enters the cell during heteroexchange, facilitating quantitation of the kinetic alterations which occur for methotrexate influx during trans-stimulation.     

Slow loss of deoxyribose from the N7deoxyguanosine adducts of estradiol-3,4-quinone and hexestrol-3',4'-quinone. Implications for mutagenic activity

A variety of evidence has been obtained that estrogens are weak tumor initiators. A major step in the multi-stage process leading to tumor initiation involves metabolic formation of 4-catechol estrogens from estradiol (E2) and/or estrone and further oxidation of the catechol estrogens to the corresponding catechol estrogen quinones. The electrophilic catechol quinones react with DNA mostly at the N-3 of adenine (Ade) and N-7 of guanine (Gua) by 1,4-Michael addition to form depurinating adducts. The N3Ade adducts depurinate instantaneously, whereas the N7Gua adducts depurinate with a half-life of several hours. Only the apurinic sites generated in the DNA by the rapidly depurinating N3Ade adducts appear to produce mutations by error-prone repair. Analogously to the catechol estrogen-3,4-quinones, the synthetic nonsteroidal estrogen hexestrol-3',4'-quinone (HES-3',4'-Q) reacts with DNA at the N-3 of Ade and N-7 of Gua to form depurinating adducts. We report here an additional similarity between the natural estrogen E2 and the synthetic estrogen HES, namely, the slow loss of deoxyribose from the N7deoxyguanosine (N7dG) adducts formed by reaction of E2-3,4-Q or HES-3',4'-Q with dG. The half-life of the loss of deoxyribose from the N7dG adducts to form the corresponding 4-OHE2-1-N7Gua and 3'-OH-HES-6'-N7Gua is 6 or 8 h, respectively. The slow cleavage of this glycosyl bond in DNA seems to limit the ability of these adducts to induce mutations.     

Derivatives of methanopterin, a coenzyme involved in methanogenesis

Degradational studies of methanopterin, a coenzyme involved in methanogenesis, are reported. The results of these studies are in full accordance with the proposed structure of methanopterin as N-[1'-(2'-amino-4'-hydroxy-7' -methyl-6'-pteridinyl)ethyl]-4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl(5'-1' )O-alpha-ribofuranosyl-5'-phosphoric acid] aniline in which the phosphate group is esterified with alpha-hydroxyglutaric acid. Acid hydrolysis of methanopterin cleaved the 5'----1' glycosidic bond and yielded a 'hydrolytic product' which was identified as N-[1'-(2'-amino-4'-hydroxy-7' -methyl-6'-pteridinyl)ethyl]-4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl]aniline. Alkaline permanganate oxidation of methanopterin yielded 7-methylpterin-6-carboxylic acid. Catalytic (or enzymatic) hydrogenation of methanopterin gave a mixture of 6-ethyl-7-methyl-7,8-dihydropterin, 6-ethyl-7-methylpterin and a third compound, named methaniline which was identified as 4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl(5'----1')O-alpha -ribofuranosyl-5'-phosphoric acid]aniline, in which the phosphate group is esterified with alpha-hydroxyglutaric acid. Methanosarcina barkeri contains a closely related coenzyme called sarcinapterin, which was identified as a L-glutamyl derivative of methanopterin, where the glutamate moiety is attached to the alpha-carboxylic acid group of the alpha-hydroxyglutaric acid moiety of methanopterin via an amide linkage.