Rare 6- and 8-O-methylated epicuticular flavonols from two Cistus species

Leaves of Cistus albanicus and C. parviflorus secrete a resin which contains several rare 6- and 8-O-methylated flavonols. In addition, some common kaempferol, quercetin methyl ethers and one myricetin methyl ether were identified. Some typical colour reactions of the 6- and 8-methoxy derivatives on polyamide TLC plates are reported. The systematic implications concerning the flavonoids found are discussed briefly.     

Bicyclo[3,2,1]octanoid,neolignans from Aniba simulans

Six bicyclo[3,2,1]octanoid neolignans, isolated from the benzene extract of Aniba simulans Allen (Lauraceae) trunk wood, are shown to derive from two basic structures: 1-allyl-8-hydroxy-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-7-methyl-3-oxobicyclo[3,2,1]octane, substituted by 4-hydroxy, 4-hydroxy-5-methoxy, 4-methoxy or 4,5-dimethoxy groups; and 1-allyl-8-hydroxy-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-7-methyl-4-oxobicyclo[3,2,1]oct-2-ene, substituted by 3-hydroxy or 3-hydroxy-5-methoxy groups. The structural proposals are based on spectral data, interconversions synthesis of a derivative from the known (2R,3S,3aS)-3a-allyl-5-methoxy-2-(3′-methoxy,4′,5′-methylenedioxyphenyl)-3-methyl-2,3,3a,6-tetrahydro-6-oxobenzofuran.     

直立百部的非生物碱化学成分研究(英文)

从直立百部(Stemona sessilifolia)根中首次分离到十四个非生物碱成分.依据波谱数据,它们鉴定为豆甾醇(1)、4-甲氧基苯甲酸(2)、苯甲酸(3)、3,4-二甲氧基苯酚 (4)、4-甲氧基苯甲酸(5)、4-羟基苯甲酸(6)、4-羟基-3-甲氧基苯甲酸(7)、4-羟基-3,5-二甲氧基苯甲酸(8)、3,3′-bis(3,4-dihydro-4-hydroxy-6-methoxy)-2H-1-benzopyran(9)、4-羟基-3-甲氧基苯甲醛(10)、羽扇豆烷-3-酮 (11)、绿原酸(12)、胡萝卜苷(13),3-feruoyl-chinasueure (14).化合物5～14为首次从百部属植物中分离得到.     

Differentiation des hydroxy-5 dimethoxy-6,7 ou 7,8 et des triméthoxy-5,6,7 ou 5,7,8 flavones par spectrometrie de masse

The relative abundance of M and M-15 peaks in the mass spectrum allows the differentiation of 5-hydroxy-6,7-dimethoxy- and 5,7,8-trimethoxyflavones (M > M-15) from 5-hydroxy-7,8-dimethoxy and 5,6,7-trimethoxy-flavones (M < M-15) respectively, thus affording a solution to the 5,6,7- or 5,7,8-orientation problem on microscale.     

Base sequence specificity of a monoclonal antibody binding to (6-4)photoproducts.

The DNA base sequence specificity of the 64M-1 monoclonal antibody, which recognizes ultraviolet (UV)-induced (6-4)photoproducts, was characterized. The 64M-1 antibody strongly bound to UV-poly(dU) as well as to UV-poly(dT), and weakly to UV-poly(dC), UV-poly(me5dC) and UV-poly(rU). A competitive inhibition assay using UV-oligo(dT)8, UV-oligo(dTdC)4, UV-oligo(dC)8, UV-PvuI linker (GCGATCGC) and UV-PvuII linker (GCAGCTGC) indicated that the main (6-4)photoproducts detected by the 64M-1 antibody in UV-irradiated DNA are TT(6-4)photoproducts and TC(6-4)photoproducts. Comparison between dTpdT(6-4)photoproduct and dTpdC(6-4)photoproduct showed that the affinity of the 64M-1 antibody for dTpdT(6-4)photoproduct was about 5 times higher than that for dTpdC(6-4)photoproduct. The antibody also binds to isolated TT(6-4)photoproducts.     

CHLOROPHYLL PIGMENTS IN METHANOL EXTRACTS FROM TEN AXENIC CULTURED DIATOMS AND THREE GREEN ALGAE AS DETERMINED BY REVERSE PHASE HPLC WITH FLUOROMETRIC DETECTION 1

Chlorophyll pigments in 100% mrthanol extracts from ten axenic cultured diatoms and three green algae were examined using reverse phase HPLC with Jluoromelric detector and field desorption mass spectrometry to identify same unknown peaks tn HPLC chromatograms from natural phytoplankton samples. Characteristics of the HPLC chromatograms were the presence of chlorophyllide and two unknown peaks. Field desorption mass spectrometry of the oxidation products of authentic chlorophyll a suggested that the peaks were due to 10-hydroxy and 10-hydroxy lactone chlorophylls a and 10-methoxy and 10-methoxy lactone chlorophylls a fanned during each process of filtration, storage at -20°C and extraction in methanol. The present results indicated that a new type of chlorophyll c derivative may exist and, as far as we use filtration to collect phytoplankton and store the sample under air even at -20°C, the formation of oxidation products of chlorophyll pigments may he unavoidable.     

Structure and species as factors affecting the metabolism of some methoxy-6-sulphanilamidopyrimidines

1. A comparative study was made in man, rhesus monkey, rat and rabbit of the urinary excretion of 2-, 4- and 5-methoxy- and 2,4-, 2,5- and 4,5-dimethoxy-6-sulphanilamidopyrimidines given orally. 2. In the rabbit, 70-80% of the dose of each drug was excreted in 2 days, mainly as N(4)-acetyl derivatives, except 2,5-dimethoxy-6-sulphanilamidopyrimidine, which was mainly excreted unchanged. 3. In the rat, 50-70% of the dose of each drug was excreted in 2 days, except the 2-methoxy and 2,4-dimethoxy compounds, whose excretion was about 30%. The N(4)-acetyl derivatives accounted for 20-70% of the drugs excreted, except the 2,5-dimethoxy derivative, which was excreted unchanged. 4. In the rhesus monkey, some 40-60% of the dose of the 2-methoxy, 2,4-dimethoxy and 2,5-dimethoxy compounds was excreted in 2 days, but the 4-methoxy, 5-methoxy and 4,5-dimethoxy compounds were excreted at less than half this rate. The 4-methoxy, 5-methoxy and 4,5-dimethoxy compounds were highly acetylated (80-90%) whereas the 2-methoxy compound was poorly acetylated (17%) and the 2,5-dimethoxy compound hardly at all. The major metabolite of the 2,4-dimethoxy compound in the monkey was the N(1)-glucuronide. 5. In man, 30% of the dose of the 4-methoxy and 2,4-dimethoxy compounds was excreted in 24 hr., whereas the 4,5-dimethoxy compound (Fanasil) was very slowly excreted (12% in 2 days). The 4-methoxy compound was well acetylated (65%), but the 2,4- and 4,5-dimethoxy compounds were not (20-30%). The main metabolite of the 2,4-dimethoxy compound in man was the N(1)-glucuronide. 6. N(1)-Glucuronide formation occurred extensively only with the 2,4-dimethoxy compound and only in man and the rhesus monkey. It did not occur in the rabbit and only to a minor extent in the rat. 7. The 2,5-dimethoxy compound was not significantly acetylated in vivo in the rabbit, rat or monkey, but acetylation occurred in vitro in rabbit or monkey liver homogenates. 8. These findings are discussed.     

Antioxidant and cytotoxic flavonols from Calotropis procera

Phytochemical investigations of Calotropis procera leaves have led to the isolation of two new compounds: quercetagetin-6-methyl ether 3-O-beta-D-4C1-galacturonopyranoside (3) and (E)-3-(4-methoxyphenyl-2-O-beta-D-4C1 -glucopyranoside)-methyl propenoate (4), along with eleven known metabolites: nine flavonol and two cinnamic acid derivatives. All metabolites were isolated for the first time from the genus Calotropis, except for 1 isolated previously from Calotropis gigantea. The structures were determined by spectroscopic methods (UV, ESI-MS, 1H, 13C NMR, 1H-1H COSY, HSQC, and HMBC). The radical scavenging activity of the aqueous methanol extract and compounds 8-13 was measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. Cytotoxic screening of the same compounds was carried out on brine shrimps as well.     

Prenylated flavonoids from Deguelia hatschbachii and their systematic significance in Deguelia

Chemical investigation of dichloromethane and petrol extracts from the roots of D. hatshbachii A. M. G. Azevedo furnished thirteen compounds from which five are described for the first time and their structures were determined to be 3-(4'-hydroxyphenyl)-5-methoxy-6-( 3,3-dimethylallyl)-2"2"-dimethylchromene-(5",6":8,7)-3-(propyl-2-one)-4H-1-benzo-2,3-dihydropyran-2,4-dione; 6,4'-dihydroxy-3-(3,3-dimethylallyl)-2",2"-dimethylchromene (5",6":5,4)-2-methoxy deoxybenzoin; 6.4'-dihydroxy-3-(3,3-dimethylallyl)-2",2"-dimethylchromene (5",6":5,4)-2-methoxy-8-(propyl-2-one) deoxybenzon; 6-(3,3-dimethylallyl)-2",2"-dimethylchromene (5",6":4.5)-4'-hydroxy-3-methoxy stilbene and 3,5-dimethoxy-4'-hydroxy-4-(3,3-dimethylallyl) stilbene by spectral analysis (UV, IR, MS and ID- and 2D- NMR experiments). The root extracts and some isolated compounds were bioactive, as revealed by bioautography and brine shrimp lethality assays.     

Conformational spaces of the gastrointestinal antisecretory chiral drug omeprazole: stereochemistry and tautomerism

A study of the conformational spaces of the chiral proton pump inhibitor (PPI) drug omeprazole by semiempirical, ab-initio, and DFT methods is described. In addition to the chiral center at the sulfinyl sulfur atom, the chiral axis at the pyridine ring (due to the hindered rotation of the 4-methoxy substituents) was considered. The results were analyzed in terms of the 5-methoxy and 6-methoxy tautomers and the two pairs of enantiomers (R,P)/(S,M) and (R,M)/(S,P). Five torsion angles were systematically explored: the backbone rotations defined by D1 (N3-C2-S10-O11), D2 (C2-S10-C12-C13), and D3 (S10-C12-C13-N14) and two methoxy rotations defined by D4 (C6-C5-O8-C9) and D5 (C16-C17-O19-C20). Significant energy differences were revealed between the 5- and 6-methoxy tautomers, the extended and folded conformations, and the (S,M) and (S,P) diastereomers. The "extended M" conformation of the 6-methoxy tautomer of (S)-omeprazole was found to be the most stable conformer.     

Triterpenes and lignans from the leaves of Styrax tonkinensis

Two triterpenes (1 and 2) and eight lignans (3–10) were isolated from the ethyl acetate-soluble fraction of the leaves of Styrax tonkinensis (Pierre) Craib ex Hartw (Styracaceae). Their structures were established as ursolic acid (1), pomolic acid (2), 3,3′-bis(3,4-dihydro-6-methoxy-2H-1-benzopyran) (3), rac-(8α,8′β)-4,4′-dihydroxy-3,3′-dimethoxylignan-9,9′-diyldiacetate (4), (-)-secoisolariciresinol (5), (+)-pinoresinol (6), 4,4′-dihydroxy-3,3′-dimethoxy-9-ethoxy-9,9′-epoxylignan (7), (2S,3R, 4R)-4-[1-ethoxy-1-(4-hydroxy-3-methoxy)phenyl]methyl-2-(4-hydroxy-3-methoxy)phenyl-3-hydroxymethyl-tetrahydrofuran (8), (-)-neo-olivil-(9-O-9″)-seco-isolariciresinol (9) and isolariciresinol (10) based on MS, ¹H-and ¹³C-NMR spectral data. All these compounds (1–10) were firstly isolated from this plant, and compounds 2–5 and 7–9 were reported from the Styrax genus for the first time. Furthermore, the chemotaxonomic significance of the isolated compounds was discussed.     

Pterocarpans from Swartzia laevicarpa

An ethanol extract of the trunkwood from Swartzia laevicarpa (Leguminosae) gave four (6aR,11aR)-8-hydroxy-3,9-dimethoxypterocarpans differentiated by additional 2-hydroxy, 2-hydroxy-10-methoxy, 4,10-dimethoxy and 2-hydroxy-4,10-dimethoxy substitution; besides two 8-hydroxy-6-methoxy-3-methylisocoumarins differentiated by 5-chloro and 7-chloro substitution; 5-hydroxy-7,8-dimethoxy-2-methylchromone and the known 8-hydroxy-5-methyl-3,4-dihydroxyisocoumarin.     

Analysis of medium-chain acyl-coenzyme A esters in mouse tissues by liquid chromatography-electrospray ionization mass spectrometry

Medium-chain acyl-coenzyme A (CoA) esters are key metabolites in lipid metabolism. Liquid chromatography-electrospray ionization mass spectrometry analysis of medium-chain acyl-CoA esters is described. Eight medium-chain acyl-CoA esters were well separated on a C(8)-MS reversed-phase column using a linear gradient of ammonium acetate buffer (pH 5.3)-acetonitrile. The positive-ion mass spectra of all the saturated and unsaturated medium-chain acyl-CoA esters gave dominant [M+H](+) ions, whereas their negative-ion mass spectra showed abundant [M-H](-) and [M-2H](2-) ions. The positive-ion mode of operation was slightly less sensitive than the negative-ion detection mode. Five medium-chain acyl-CoA esters of C(6:0), C(8:0), C(8:1), C(10:0), and C(10:1) in liver, heart, kidney, and brain from the mouse were identified. The predominant acyl-CoA peaks were C(6:0), C(8:0), and C(10:0). Small amounts of medium-chain acyl-CoAs of C(8:1) and C(10:1) were detected only in heart and kidney. The analytical method is very useful for the analysis of medium-chain acyl-CoA esters in the tissues.     

Interaction of linear manno-oligosaccharides with three mannose-specific bulb lectins. Comparison with mannose/glucose-binding lectins.

Three new mannose-binding lectins, isolated from daffodil (NPA), amaryllis (HHA), and snowdrop (GNA) bulbs, are capable of precipitating with a linear mannopentaose (Man alpha 1-3Man alpha 1-3Man alpha 1-3Man alpha 1-2Man). NPA and HHA reacted strongly with the mannopentaose whereas GNA gave a precipitate only at concentrations greater than 500 microM. A phosphate group at C-6 of the nonreducing terminal mannosyl group prevented precipitation in all three cases. The reduced (NaBH4) mannopentaose, Man4Man-ol, did not precipitate with GNA or NPA, but was active with HHA. This activity was lost when Man4Man-ol was converted (NaIO4 then NaBH4; mild acid hydrolysis of the reduced product) into trisaccharide derivatives. With alpha-D-Manp-OMe the three lectins gave UV difference spectra having large positive peaks at 292-293 and 283-284 nm, and a small positive peak at 275 nm, characteristic of tryptophanyl and tyrosyl residues. The association constants for the interaction with alpha-D-Manp-OMe were very low (NPA, 86; HHA, 66; and GNA, 41 M-1), but the lectins bound methyl (1----3)-alpha-mannobioside with increased affinity (K for NPA 540, for HHA 2400, and for GNA 200 M-1). The bulb lectins lack binding sites for hydrophobic ligands, as judged by their failure to interact with the fluorescent probes 8-anilino-1-napthalenesulfonic acid (ANS) and 6-p-toluidino-2-naphthalenesulfonic acid (TNS).     

镰刀菌毒素的研究II．T-2毒素的提取、纯化及结构鉴定

本文报道了三线镰刀菌M-20(Fusarium tricinctum)接种于已灭菌的玉米粒培养基中,于13℃培养30天后,提取培养物所得粗毒素。经二次硅胶柱层析纯化后,经丙酮-正己烷结晶,可获得白色针状结晶。根据它的熔点(151—2℃)R_f0.56,LD_(50)2.5,mg/kg。分子量466,FD质谱测定,~1H核磁共振谱及EI质谱,确证结晶为T-2毒素。     

Effects of 4- and 8-h preexercise feedings on substrate use and performance

Seven well-trained male cyclists were studied during 105 min of cycling (65% of maximal oxygen uptake) and a 15-min "performance ride" to compare the effects of 4- and 8-h preexercise carbohydrate (CHO) feedings on substrate use and performance. A high CHO meal was given 1) 4-h preexercise (M-4), 2) 8-h preexercise (M-8), 3) 4-h preexercise with CHO feedings during exercise (M-4CHO), and 4) 8-h preexercise with CHO feedings during exercise (M-8CHO). Blood samples were obtained at 0, 15, 60, 105, and 120 min and analyzed for lactate, glucose, insulin, and glycerol. Total work output during the performance ride was similar for the M-4 (217,893 +/- 13,348 N/m) and M-8 trials (216,542 +/- 13,905) and was somewhat higher for the M-4CHO (223,994 +/- 14,387) and M-8CHO (224,702 +/- 15,709) trials (P = 0.059, NS). Glucose was significantly elevated throughout exercise, and insulin levels were significantly elevated at 15 and 60 min during M-4CHO and M-8CHO compared with M-4 and M-8 trials. Glycerol levels were significantly lower during the CHO feeding trials compared with placebo and were not significantly different during exercise when the subject had fasted an additional 4 h. The results of this study suggest that when preexercise meals are ingested 4 or 8 h before submaximal cycling exercise, substrate use and performance are similar.     

Comparison of the self-association properties of the 5'-triphosphates of inosine (ITP), guanosine (GTP), and adenosine (ATP). Further evidence for ionic interactions in the highly stable dimeric [H2(ATP)]2(4-) stack

The concentration dependence of the chemical shifts for the hydrogens H-2, H-8 and H-1' of ITP and for H-8 and H-1' of GTP has been measured in D2O at 25 degrees C under several degrees of protonation in the pD range 1.2-8.4. For reasons of comparison, inosine and guanosine have been included in the study The results are consistent with the isodesmic model of indefinite noncooperative stacking. The association constants for the nucleosides (Ns) inosine and guanosine decrease with increasing protonation: Ns greater than D(Ns)+/Ns in a 1:1 ratio greater than D(Ns)+. In contrast, a maximum is observed with ITP and GTP; the stacking tendency of GTP following the series: GTP4- less than or equal to D(GTP)3- (K approximately 0.7 M-1) less than D(GTP)3-/D2(GTP)2- in a 1:1 ratio (K approximately 2.9 M-1) greater than D2(GTP)2- greater than D3(GTP)- (K approximately 1.5 M-1). The order of the series with ITP corresponds to that with GTP, but the association constants are slightly smaller. At the maximum of the self-association tendency the triphosphate residue has only a minor influence; this follows from the fact that the association constants for the 1:1 ratios of Ino/D(Ino)+ and D(ITP)3-/D2(ITP)2- are identical within experimental error; this holds also for Guo/D(Guo)+ and D(GTP)3-/D2(GTP)2-; in all these pairs the K-7 site is 50% protonated. Comparison of the association constant for the deprotonated species shows that here charge effects, i.e. repulsion between the negatively charged triphosphate chains, are important: Ino (K approximately 3.3 M-1) greater than ITP4- (K approximately 0.4 M-1) and Guo (K approximately 8 M-1) greater than GTP4- (K approximately 0.8 M-1). In addition the series holds: Ado (K approximately 15 M-1) greater than Guo greater than Ino. However, most important is the comparison of the ITP and GTP series with previous data for ATP: ATP4- (K approximately 1.3 M-1) less than D(ATP)3- (2.1 M-1) less than 1:1 ratio of D(ATP)3-/D2(ATP)2- (6 M-1) much less than D2(ATP)2- (approximately 200 M-1) much greater than D3(ATP)- (K less than or equal to 17 M-1).(ABSTRACT TRUNCATED AT 400 WORDS)     

Novel type of very high affinity calcium-binding sites in beta-hydroxyasparagine-containing epidermal growth factor-like domains in vitamin K-dependent protein S

Vitamin K-dependent protein S is shown to contain four very high affinity Ca2(+)-binding sites. The number of sites and their affinities were determined from Ca2+ titration in the presence of the chromophoric chelator Quin 2. In 0.15 M NaCl, pH 7.5, the four macroscopic binding constants are K1 greater than or equal to 1 x 10(8) M-1, K2 = 3 +/- 2 x 10(7) M-1, K3 = 4 +/- 2 x 10(6) M-1, and K4 = 9 +/- 4 x 10(5) M-1. At low ionic strength, the corresponding values are K1 greater than or equal to 2 x 10(9) M-1, K2 = 9 +/- 4 x 10(8) M-1, K3 = 2 +/- 1 x 10(8) M-1, and K4 = 9 +/- 4 x 10(7) M-1. To localize the Ca2(+)-binding sites, protein S was subjected to proteolysis using lysyl endopeptidase. This yielded a 20-21-kDa fragment which comprised the third and fourth epidermal growth factor (EGF)-like domains and remained high affinity Ca2(+)-binding site(s). The susceptibility of the EGF-like domains to proteolysis increased when Ca2+ was removed from protein S indicating that the Ca2+ binding is important for the stability and/or conformation of the EGF domains. Three of the four EGF-like domains in protein S contain beta-hydroxyasparagine. In each of these domains there is a cluster of three or four negatively charged amino acid residues which are likely to contribute to the extraordinary high Ca2+ affinity. From sequence homology it is suggested that this novel type of high affinity Ca2(+)-binding site is present in several other proteins, e.g. in the EGF-like domains in the low sensity lipoproteins receptor, thrombomodulin, the Notch protein of Drosophila melanogaster, and transforming growth factor beta 1-binding protein.     

Complex formation of double-stranded DNA (6-4) photoproducts and anti-(6-4) photoproduct antibody Fabs.

DNA (6-4) photoproducts are major constituents of ultraviolet-damaged DNAs. We prepared double-stranded (ds) (6-4) DNA photoproducts and analyzed formation of their complexes with anti-(6-4) photoproduct antibody Fabs. Elution profiles of the mixtures of ds-(6-4) DNAs and Fabs from anion-exchange and gel-filtration columns indicate that Fab 64M-2 deprives 14mer ds-(6-4) DNA of single-stranded (ss) (6-4) DNA and shows no interaction with 18 mer ds-(6-4) DNA (A18). Fab 64M-5 with an approximately 100-fold higher affinity than Fab 64M-2 forms a complex with the ds-(6-4) DNA (A18), but partly dissociates another 18 mer ds-(6-4) DNA (A18-3), with a lowered G-C content, into ss-DNAs. From these results, antibody 64M-5 possibly accommodates the T(6-4)T photolesion moiety of the ds-(6-4) DNA (A18) by flipping out the moiety from its neighboring segments.     

Oxygen binding to dithionite-reduced chloroperoxidase

Both the kinetics of ferric chloroperoxidase reduction by dithionite and the binding of molecular oxygen to ferrous chloroperoxidase have been studied. The oxyferrous chloroperoxidase decays spontaneously to the ferric enzyme. In addition the corresponding rapid-scan spectra have been recorded. The reduction reaction is caused by SO-.2 with a rate constant of (7.7 +/- 1.0) X 10(4) M-1 S-1. Oxygen binding occurs with a rate constant of (5.5 +/- 1.0) X 10(5) M-1 S-1 over the pH range 3.5-6. Oxyferrous chloroperoxidase has a Soret absorption peak at 428 nm and two partially resolved peaks at 555 nm and 588 nm. Isosbestic points occur at the following wavelengths: between ferrous and oxyferrous chloroperoxidase at 419, 545, 555 and 580 nm; between oxyferrous and ferric chloroperoxidase at 419, 487, 540, 609 and 682 nm.