A study of the formation of fluorescent derivatives of 4-hydroxyphenethylamine (tyramine), 4-hydroxy-3-methoxyphenethylamine (3-methoxytyramine) and related compounds by reaction with hydrazine in the presence of nitrous acid

A reaction is described that allows the preparation of fluorescent derivatives of a group of related compounds with the basic 4-hydroxyphenethylamine structure. Examination of the reaction shows that it takes place in two stages, which can be considered separately. (1) Reaction of hydrazine with nitrous acid: this is instantaneous at room temperature and involves the reaction of 1 mol of hydrazine with 2 mol of nitrous acid. (2) Reaction with 4-hydroxyphenethylamine compounds: this occurs slowly at room temperature but the rate of reaction is significantly increased at higher temperatures. Ammonium sulphamate is added to remove excess of nitrous acid, found to be detrimental to the reaction. Examination of reagent concentrations necessary for maximum fluoresence yield demonstrated the need for a 40-fold molar excess of the reagent formed in the first stage. The derivatives fluoresce in alkaline solution, the fluorescence of derivatives of 4-hydroxy compounds being stable for over 1h at room temperature, those of 4-hydroxy-3-methoxy compounds being slightly less stable. The derivatives were distinguishable from their parent compounds by t.l.c.     

Quantitative PAS assay of some carbohydrate compounds and detergents.

A spectrophotometric method for determination of color development of glycocompounds subjected to PAS reaction was investigated with various carbohydrate compounds and related chemicals. The conditions of the oxidation with periodic acid was found to influence the amount of the colored Schiff dye produced. Mono- and di-saccharides (mannose, glucose and maltose) were PAS-negative. Glycogen was more reactive than dextran. When glycogen was hydrolyzed by amylase the intensity of the PAS product dropped until a certain limit probably reflecting the limit dextrin. The presence of proteins (albumin) or electrolytes (NaCl) did not influence the PAS reaction. Many non-ionic detergents commonly used in membrane biology such as alkyl glycosides and gluco-methyl alkanamides were strongly PAS-positive and so was the anionic detergent SDS while the zwitterionic detergents tested, such as CHAPS and CHAPSO, were PAS-negative. The color development of the spectrophotometric PAS reaction showed linearity with the concentration of a simple glycoprotein solution (peroxidase) and a complex solution (bovine serum). By the PAS reaction it was also possible to measure the content of soluble and membrane bound carbohydrate compounds in a pellet of liver cell membranes. We find that the PAS reaction is sensitive and reliable for quantitative estimations of complex carbohydrates as well as soluble and membrane-bound carbohydrate compounds. The latter should be treated with PAS-unreactive zwitterionic detergents.     

The Action of Nine Chelators on Iron-Dependent Radical Damage

Nine iron chelators were tested in five systems for their effects on radical-generation and conversion at chelator: iron molar ratios from 0.1 to 10. Stimulatory actions might distinguish toxic from safer chelators. Radical-generating reactions which represent different aspects of iron (ferrous and ferric) availability were studied: a) the reaction with hydrogen peroxide to hydroxylate benzoate; b) the oxidation of ascorbate; c) the reaction with hydrogen peroxide to fragment proteins; d) the reaction with hydrogen peroxide to permit amplified chemiluminescence; and e) the induction of peroxidation of mitochondrial membrane lipids. The compounds used were HBED, CP130, Desferal, EDTA, pyridine-hydrazone (CGP 43'902B), Ferrozine, CP 94 (CGP 46'700), LI (CGP 37 391) and rhodotorulic acid (CGP 45 274). Only the hexadentate compounds HBED, CP130 and Desferal were uniformly inhibitory (“protective”). The protective compounds were also apparently more stable during radical fluxes than the other chelators.     

Lead-catalyzed peroxidation of essential unsaturated fatty acid

In the present study, the reaction mixtures (lead compounds with essential unsaturated fatty acids) were preincubated at 37°C for 24 h prior to the measurement of malondialdehyde (MDA) by HPLC. The metal-catalyzed reactions were also compared in the presence of butylated hydroxytoluene (BHT), a free radical scavenger. Our results showed that according to the difference in the number of double bonds of essential unsaturated fatty acids, the kinds of lead compounds, and the concentrations of lead compounds, the extent of lipid peroxidation was different. The addition of BHT to the reaction mixtures significantly reduced the production of MDA (P<0.01). These in vitro studies support prior in vivo reports that the important mechanism of the acute toxic effects of the lead compounds is owing at least in part, to metal-catalyzed peroxidation of polyun-saturated fatty acids.     

Effect of O-glycosilation on the antioxidant activity and free radical reactions of a plant flavonoid,chrysoeriol

Chrysoeriol and its glycoside (chrysoeriol-6-O-acetyl-4'-beta-D-glucoside) are two natural flavonoids extracted from the tropical plant Coronopus didymus. The aqueous solutions of both the flavonoids were tested for their ability to inhibit lipid peroxidation induced by gamma-radiation, Fe (III) and Fe (II). In all these assays chrysoeriol showed better protecting effect than the glycoside. The compounds were also found to inhibit enzymatically produced superoxide anion by xanthine/xanthine oxidase system; here the glycoside is more effective than the aglycone. The rate constants for the reaction of the compounds with superoxide anion determined by using stopped-flow spectrometer were found to be nearly same. Chrysoeriol glycoside reacts with DPPH radicals at millimolar concentration, but the aglycone showed no reaction. Using nanosecond pulse radiolysis technique, reactions of these compounds with hydroxyl, azide, haloperoxyl radicals and hydrated electron were studied. The bimolecular rate constants for these reactions and the transient spectra of the one-electron oxidized species indicated that the site of oxidation for the two compounds is different. Reaction of hydrated electron with the two compounds was carried out at pH 7, where similar reactivity was observed with both the compounds. Based on all these studies it is concluded that chrysoeriol exhibits potent antioxidant activity. O-glycosylation of chrysoeriol decreases its ability to inhibit lipid peroxidation and reaction with peroxyl radicals. However the glycoside is a more efficient scavenger of DPPH radicals and a better inhibitor of xanthine/xanthine oxidase than the aglycone.     

Synthesis and cytotoxic evaluation of analogues of the marine pyridoacridine amphimedine

4-Substituted-7H-pyrido-[4,3,2-de][1,8] or [1,9]-phenanthroline-7-ones and 9-methyl-1,4-diazanaphtacene-3,10-dione, analogues of the marine pyridoacridine amphimedine were synthesised from isoquinoline-5,8-dione. The first compounds were obtained starting from a Diels-Alder reaction whereas the synthesis of the last compound was initiated by a reaction of condensation with 2-aminoacetophenone. The different tetra- and pentacyclic compounds were evaluated for in vitro cytotoxic activities against six distinct human cancer cell lines. All the compounds exhibit cytotoxic activity with IC(50) values (i.e., the drug concentration inhibiting the mean growth value of the six cell lines by 50%)<10(-7)M for two of them.     

Alumina-supported synthesis of antibacterial quinolines using microwaves

7-(5'-Alkyl-1',3',4'-thiadiazol/oxadiazol-2'-ylthio)-6 -fluoro-2,4-dimethylquinolines and 3-formyl-2-(2'-hydroxy- 1',4'-naphthoquinon-3'-yl)-4-methyl/6-methyl/7-quinolines have been synthesised by the reaction of 5-alkyl-1,3,4-thiadiazol/oxadiazol-2-thiols with 7-chloro-6-fluoro-2,4-dimethylquinoline and by the reaction of 2-hydroxy-1,4-naphthoquinone with 2-chloro-3-formyl-4-methyl/6-methyl/7-methyl/8-methylquinolines respectively on basic alumina using microwaves, the reaction time has been brought down from hours to seconds with improved yield as compared to conventional heating. The compounds were tested for their in vitro antibacterial activity. All compounds showed promising antibacterial activity. The best activity was observed by compounds 3a and 3f.     

Synthesis and Biological Evaluation of Novel 1‐(4‐(Hydroxy(1‐oxo‐1,3‐dihydro‐2H‐inden‐2‐ylidene)methyl)phenyl)‐3‐phenylurea Derivatives

A series of novel phenylurea containing 2‐benzoylindan‐1‐one derivatives 3a  –  3j were synthesized from the reaction of phenylurea‐substituted acetophenones 1a  –  1j with phthalaldehyde 2 under mild reaction conditions in good yields. All synthesized compounds were characterized by spectroscopic methods. The obtained compounds ( 3a  –  3j ) were evaluated for anticancer activity against HeLa and C6 cell lines. Antiproliferative activity was determined by the BrdU proliferation ELISA assay, 3f and 3g were found to be most active compounds. The compounds were also screened for antimicrobial activity and all compounds showed remarkable activity against used microorganisms.     

Synthesis of new arylalkoxy amido derivatives as melatoninergic ligands

Amido derivatives 10-18 of the corresponding oxyamines were synthesised as melatoninergic ligands by the reaction of hydroxyphtalimide with the halogeno derivatives or the corresponding alcohols using Mitsunobu reaction conditions. The affinity of the compounds for chicken brain melatonin receptors and recombinant human MT(1) and MT(2) receptors was evaluated using 2-[125I]-iodomelatonin as the radioligand. Overall, the introduction of an oxygen atom in the amido chain was not a favourable parameter as the compounds were less potent than the corresponding deoxy derivatives. However, nanomolar compounds were obtained with the arylethyloxy derivatives (13c (R'=nPr), chicken brain, hMT(1), hMT(2), K(i) values: 4.8, 3.86, 2.4 nM, respectively) and the 2,7-dimethoxynaphthalene derivatives (17c (R'=nPr), chicken brain, hMT(1), hMT(2), K(i) values: 0.04, 0.13, 0.1 nM, respectively). The functional activity of these compounds was evaluated by the aggregation of melanophores in Xenopus laevis tadpoles and the potency was related to the affinity of the molecules for melatonin receptors. The compounds were found to be full agonists and compound 17a was 20-fold more potent than melatonin in this bioassay.     

Synthesis, antiproliferative and antifungal activities of some 2-(2,4-dihydroxyphenyl)-4H-3,1-benzothiazines

A new method for the synthesis of 4H-3,1-benzothiazine skeleton is described. The compounds were obtained by the reaction of sulfinylbis(2,4-dihydroxythiobenzoyl) with o-substituted anilines bearing an activated methylene group (-CH2OH, -CH2NR1R2), o-aminobenzanilides or 2-aminobenzophenones. The reaction proceeded through thiobenzanilide intermediates, which were converted to the 4H-3,1-benzothiazine fused ring by an endocyclization process. The compounds were tested for their antiproliferative properties against the cells of a human breast cancer T47D line. The activity of some compounds was comparable to that of cisplatin, studied as a control. A strong antifungal effect against the strains of moulds, yeasts and dermatophytes was also found.     

Synthesis and antiproliferative activity of some steroidal lactone compounds

Using cholesterol as starting material, some steroidal lactone compounds with the structures of 3-substituted-6-oxo-7-oxa-B-homo-cholestane or 3-substituted-7-oxo-6-oxa-B-homo-cholestane were synthesized by oxidation, reduction, Baeyer-Villiger reaction and condensation reaction. The cytotoxicity of these compounds against MGC 7901 (human gastric carcinoma), HeLa (human cervical carcinoma) and SMMC 7404 (human liver carcinoma) cells was investigated. Our results showed that the synthesized compounds displayed a distinct cytotoxicity against these cancer cells. In particular, compounds 8 and 9 have similar cytotoxic capability as cisplatin does. The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.     

Schiff bases formed from retinal and phosphatidylethanolamine, phosphatidylserine, ethanolamine or serine

1. Conditions were established for the reaction of retinal with phosphatidylethanolamine, phosphatidylserine, ethanolamine and serine in chloroform, ethanol or ethanol–water solutions to form retinylidene compounds, or Schiff bases. 2. The Schiff bases were reduced to retinyl compounds with sodium borohydride. 3. Absorption maxima and molar extinction coefficients were determined for the various retinylidene and retinyl compounds and for the corresponding coloured products formed by their reaction with antimony trichloride.     

Effect of external factors on the kinetic properties of PGH-synthase

The influence of external factors, viz. reaction mixture temperature, presence of low- and high-molecular (tween-20) organic compounds, urea and the solution high ionic strength on kinetic properties of PGH synthetase has been studied. Some factors (high ionic strength, addition of organic compounds) were found to slow down irreversible inactivation of PGH synthetase in the course of the reaction. Sensitivity of the enzyme to the change of the solution ionic strength depends on environmental factors, rising on the microsomal enzyme solubilization with tween-20 and decreasing on further enhancement of the tween-20 concentration.     

Inhibition of bacteriophage-Q beta ribonucleic acid polymerase by guanosine triphosphate analogues.

Sixteen compounds related to GTP were evaluated as inhibitors of bacteriophage-Q beta poly(C)-dependent poly(G) polymerase. Non-phosphorylated compounds, including guanine, guanosine and deoxyguanosine, were inactive. Phosphorylated compounds gave significant inhibition at millimolar concentrations. For nucleotides the feature important for inhibition was the 5'-phosphate chain. Four triphosphates, XTP, ITP, 7-methyl-GTP and 2'-O-methyl-GTP, gave 50% inhibition of both the poly(C)- and poly(U2,C)-dependent reactions at concentrations from 0.1 to 5 mM. XTP was 10-fold more potent an inhibitor of the reaction with poly(U2,C) as template. None of these four compounds was able to substitute for GTP as substrate to a significant extent. The most active compound, 2'-O-methyl-GTP, was a competitive inhibitor (Ki = 0.4 mM) of GTP in the poly(C)-dependent reaction.     

武夷岩茶炭焙工艺对肉桂乌龙茶挥发性组分的影响

以武夷岩茶当家茶树品种肉桂(Camellia sinensis ‘Rougui’)鲜叶制成的乌龙茶为试材,基于顶空固相微萃取法(HS-SPME)结合气相色谱-质谱联用技术(GC-MS),探讨武夷岩茶炭焙工艺对肉桂乌龙茶挥发性组分的影响。实验中共检测到样本挥发性成分443个,其中包括96个杂环化合物、81个酯类化合物、31个萜类化合物、42个芳香烃类化合物、55个酮类化合物、24个其他烃类化合物、35个醇类化合物、24个醛类化合物、15个酚类化合物、14个胺类化合物、10个酸类化合物、5个含氮化合物、3个含硫化合物等。经主成分分析及聚类分析显示,焙火工艺是影响乌龙茶挥发性成分含量的重要影响因子。随炭焙程度增加,不同类别物质中的多数挥发性成分含量随之显著升高,且以美拉德反应产物等具有茶叶烘炒香的吡嗪类、糠醛类衍生物、吡咯类等化合物最具代表性;同时,部分含量丰富且具有乌龙茶特殊花果香气的醇类、萜烯类物质如香叶醇、反式-橙花叔醇、植物醇、α-法尼烯等,及具清新花香的吲哚含量显著降低。然而,大多数挥发性差异代谢物随炭焙程度增加相对含量显著升高,并不代表茶叶中芳香物质总量增加。研究表明,乌龙茶精制烘焙过程中,香气物质的积累主要来自热作用下的美拉德反应及非酶促的降解和氧化,如黄酮苷类物质水解。     

Synthesis of 8,9-leukotriene A4 by murine 8-lipoxygenase

Arachidonate 8-lipoxygenase was identified in phorbol ester induced mouse skin. We expressed the enzyme in an Escherichia coli system using pET-15b carrying an N-terminal histidine-tag sequence. The enzyme, purified by nickel-nitrilotriacetate affinity chromatography, showed specific activity of about 0.1 micromol/min/mg of protein with arachidonic acid as a substrate. When metabolites of arachidonic acid were reduced and analyzed by reverse-phase HPLC, 8-hydroxy derivative was a major product as measured by absorbance at 235 nm. In addition, three polar compounds (I, II, and III) were detected by measuring absorbance at 270 nm. These compounds were also produced when the enzyme was incubated with 8-hydroperoxyeicosa-5,9,11,14-tetraenoic acid. Neither heat-inactivated enzyme nor mutated enzyme produced these compounds, suggesting that they are enzymatically generated. Ultraviolet spectra of these compounds showed typical triplet peaks around 270 nm, indicating that they have a triene structure. Molecular weight of these compounds was determined to be 336 by liquid chromatography-mass spectrometry, indicating that they carry two hydroxyl groups. Compounds I and III were generated even under anaerobic condition, indicating that oxygenation reaction was not required for their generation from 8-hydroperoxyeicosa-5,9,11,14-tetraenoic acid. By analogy to the reactions of 5-lipoxygenase pathway where leukotriene A4 is generated, it is suggested that 8-hydroperoxyeicosa-5,9,11,14-tetraenoic acid is converted by the 8-lipoxygenase to 8,9-epoxyeicosa-5,10,12,14-tetraenoic acid which degrades to compounds I and III by non-enzymatic reaction. In contrast, compound II was not generated under anaerobic condition, indicating that it was produced by oxygenation reaction. Taken together, 8-lipoxygenase catalyzes both dehydration reaction to yield 8,9-epoxy derivative and oxygenation reaction presumably at 15-position of 8-hydroperoxyeicosa-5,9,11,14-tetraenoic acid.     

Hyperthermic and anorectic effects of oxazolidines derived from L-ephedrine in rats

Oxazolidines synthesized from (-) ephedrine have been proposed as potential pro-drugs, but no pharmacological data on these compounds has been yet reported. In this study, four such compounds are tested in rats for ephedrine-like activity using the hyperthermia and anorexia models. The compounds were synthesized by reaction of (-) ephedrine with salicylaldehyde, acetone, cyclohexanone, and benzaldehyde, respectively. The results showed that all of the compounds decreased food intake significantly, but only the acetone and the salicylaldehyde derivatives caused a significant elevation of body temperature. All of the compounds were less effective than (-) ephedrine in the anorexia model. The acetone and salicylaldehyde derivatives showed similar potency to (-) ephedrine in the hyperthermia model.     

The reaction of formaldehyde with unsaturated fatty acids during histological fixation

Synopsis Formaldehyde reacts with unsaturated fatty acids in tissues during histological fixation. The reaction of formaldehyde with oleic acid has been found to given rise to compounds (adducts) with the following structures: Two other compounds were isolated but their nature is still open to doubt.The equilibrium constant for the initial part of the reaction has been approximately estimated as 0·042 at a room temperature of 22°C. The endothermic heat of reaction has been estimated as approximately 12·6 kcal.The occurrence of these adducts in tissues explains why it is that less lipid can be demonstrated histologically in material that has been stored in form-aldehyde for a considerable length of time.     

Synthesis and in Vitro Anti-Tumor Activity of A New Class of Acyclic Thioglycosides

The reaction of sodium 2-cyano-ethylene-1-thiolate salts with 2,3,4,6-tetra-O-acetyl-D-gluco- and D-galactopyranosyl bromides and with 2,3,4-tri-O-acetyl-D-xylo-. and L-arabinopyranosyl bromides, respectively, afforded new thioglycosides. Heating of the resultout glycosides with hydrazine produced pyrazole derivatives. The cytotoxicities toward the hepatoma cell line (HEPG2) of some synthesized compounds were tested. Some compounds showed high cytotoxic activity against (HEPG2) cell line. The OH moieties in the free glycosides were vital for potency. The synthesis procedures, spectroscopic data and antitumor activities for the prepared compounds are reported herein.     

Glutathione content of cultured cells and rodent brain regions: A specific fluorometric assay

The glutathione contents of cultured cells and rodent brain were determined by a fluorometric procedure which eliminates the interference of endogenous histidine-containing compounds. Cultured neonatal rat and hamster astrocytes, human dermal fibroblasts, and mouse and rat brain regions were assayed. o-Phthalaldehyde forms a fluorescent complex with glutathione, oxidized glutathione, and histidyl compounds in the absence of added thiol. The reaction of histidyl compounds can be abolished by the addition of formaldehyde to the reaction mixtures. A 10-pmol quantity of glutathione can be measured in dilute formic acid extracts of milligram quantities of tissue.