Synthesis of L-2-oxothiazolidine-4-carboxylic acid

An improved synthesis of L-2- oxothiazolidine -4-carboxylic acid is described. The new procedure, which leads to excellent yields of product, does not require the use of phosgene. The new method is thus less hazardous than the original one, and is readily adaptable to the preparation of 35S-labeled product.     

The 5-hydrazino-3-methylisothiazole-4-carboxylic acid,its new 5-substituted derivatives and their antiproliferative activity

Currently, the basic method of treatment of colon cancer is surgery. The range of anticancer drugs used in the treatment of colorectal cancer is small and is based mainly on systemic combination chemotherapy. As a result of the designed syntheses, we received new isothiazole derivatives with anticancer activity. The synthesized 5-hydrazino-3-methylisothiazole-4-carboxylic acid has never been obtained before. It is also a substrate for the synthesis of its innovative derivatives, i.e. compounds that are Schiff bases. The identification of the structure of new compounds was carried out using mass spectrometry (MS), proton nuclear magnetic resonance spectroscopy (¹H NMR), carbon nuclear magnetic resonance spectroscopy (¹³C NMR) and infrared spectroscopy (IR). Potential antitumor activity was confirmed in antiproliferative MTT and SRB tests. The selected, most biologically active substances were characterized by high selectivity towards leukemia and colon cancer cell lines. They caused high inhibition of proliferation of human biphenotypic B cell myelomonocytic leukemia MV4-11 (13 compounds), human colon adenocarcinoma cell lines sensitive LoVo (8 compounds) and resistant to doxorubicin LoVo/DX (12 compounds). However, in the conducted studies, their activity against breast adenocarcinoma MCF-7 and normal non-tumorigenic epithelial cell line derived from mammary gland MCF-10A was substantially lower. The result of this work is claimed Polish patent application.     

Crystal structure of L-2-oxothiazolidine-4-carboxylic acid

Crystals of the title compound, L-2-oxothiazolidine-4-carboxylic acid, OTC (C4H5NO3S), grown from an aqueous solution are orthorhombic, space group P2(1)2(1)2(1) with the following cell parameters at 22 +/- 3 degrees: a = 5.381(1), b = 5.961(1), c = 17.929(3)A, V = 575.1A(3), Mr = 146.2, Dc = 1.688 g.cm-3, mu = 43.9 cm-1 and Z = 4. The crystal structure was solved by the application of direct methods and refined to an R value of 0.032 for 596 reflections with I greater than 3 sigma(I). The thiazolidine ring adopts a "twist" conformation. This structure contains a short (2.619(3)A) intermolecular hydrogen bond between the carboxyl OH and the oxygen of the 2-oxo moiety, a feature common to most acyl amino acids and acyl peptides.     

1-Thiazol-2-yl-N-3-methyl-1H-pyrozole-5-carboxylic acid derivatives as antitumor agents

A class of substituted 1-thiazol-2-yl-N-3-methyl-1H-pyrozole-5-carboxylic acid derivatives was found to have potent anti-proliferative activity against a broad range of tumor cell lines. A compound from this class (14) was profiled across a broad panel of hematologic and solid tumor cancer cell lines demonstrating cell cycle arrest at the G0/G1 interphase and has potent anti-proliferative activity against a distinct and select set of cancer cell types with no observed effects on normal human cells. An example is the selective inhibition of human B-cell lymphoma cell line (BJAB). Compound 14 was orally bioavailable and tolerated well in mice. Synthesis and structure activity relationships (SAR) in this series of compounds are discussed.     

Photoaffinity labelling of the 2-oxoglutarate binding site of prolyl 4-hydroxylase with 5-azidopyridine-2-carboxylic acid

The synthesis of the photoaffinity label 5-azidopyridine-2-carboxylic acid is described. The 2-oxoglutarate analogue photoaffinity label is a competitive inhibitor with respect to 2-oxoglutarate with a Ki value of 9 X 10(-3) M. Upon ultraviolet irradiation, 5-azidopyridine-2-carboxylic acid inactivated prolyl 4-hydroxylase irreversibly by up to 50%. The extent of inactivation depended on the 5-azidopyridine-2-carboxylic acid concentration and the irradiation time. Inactivation was prevented in the presence of an excess of 2-oxoglutarate. It is concluded that the 5-azidopyridine-2-carboxylic acid became covalently bound to the alpha subunit of prolyl 4-hydroxylase, as the alpha subunit of the photoaffinity labelled enzyme had a decreased electrophoretic mobility in polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate.     

The lactam of alpha-guanidinoglutaric acid (1-amidino-2-pyrrolidone-5-carboxylic acid)

alpha-Guanidinoglutaric acid (alpha-GGA) has been reported to occur in the cerebral cortex after epileptic seizures. No physical characteristics of alpha-GGA have been given. A practical procedure for the preparation of alpha-GGA is reported here. alpha-GGA forms a lactam in aqueous solution at 80 degrees C. It is proposed to substitute this lactam, 1-amidino-2-pyrrolidone-5-carboxylic acid (pAGlu), for pyroglutamic acid (pGlu) at the N-terminal position in neuropeptides to modify their biological characteristics. L(+)-Glutamic acid was reacted with S-methylisothiourea (I) at pH 10 in aqueous solution to form L(-)-alpha-guanidinoglutaric acid: mp 165-168 degrees C, [alpha]22D = -22.7 (C = 4, 2 M HCl). alpha-GGA reacted promptly with excess reagent to form a salt, S-methylisothiourea-alpha-guanidinoglutarate: mp 209-210 degrees C, [alpha]22D = -13.0 (C = 4, 2 M HCl). I was removed from the salt with aqueous picric acid, since I readily formed an insoluble picrate, S-methylisothiourea picrate (mp 225-228 degrees C). Alternatively, the salt was added to a cation exchange column, and the alpha-GGA was eluted with molar ammonium acetate buffer, pH 9.5. Its lactam, 1-amidino-2-pyrrolidone-5-carboxylic acid, mp 248-249 degrees C, [alpha]22D = +2.1 (C = 4, 2 M HCl), formed a picrate (mp 196-199 degrees C).     

4-Hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester derivatives as potent anti-tumor agents

Based on the structure of 4-hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester (1), which exhibits selective cytotoxicity against a tumorigenic cell line, (2,4-dimethoxyphenyl)-(4-hydroxy-3-methyl-6-phenylbenzofuran-2-yl)-methanone (18m) was designed and synthesized as a biologically stable derivative containing no ester group. Although the potency of 18m was almost the same as our initial hit compound 1, 18m is expected to last longer in the human body as an anticancer agent.     

Synthesis of [(2S,3S,4R)-3,4-dihydroxypyrrolidin-2-yl]-5-methylfuran-4-carboxylic acid derivatives: new leads as selective beta-galactosidase inhibitors

The preparation of [(2S,3S,4R)-3,4-dihydroxypyrrolidin-2-yl]furan derivatives in a stereoselective route starting from D-glucose and ethyl acetoacetate is presented. Ethyl ester (6), N,N-diethylamide (7) and N-isopropylamide (8) have been tested towards 25 glycosidases. Ester (6) is a selective inhibitor of beta-galactosidases. The new compounds represent a new type of imino-C-nucleoside analogues.     

Pyrroline-5-carboxylic acid reductase from soybean leaves

Pyrroline-5-carboxylic acid reductase was purified 40-fold from soybean leaves (Glycine max L. var Corsoy). The enzyme was fairly unstable, had a broad pH optimum, and was inactivated by heat and acid; NADH and NADPH both served as cofactors. It had a higher activity with NADH (about 4 ×) compared to NADPH, but a lower K_m for NADPH. NADP⁺ inhibited both the NADH- and NADPH-dependent activity. Sulfhydryl group blocking agents reduced the activity as did the carbonyl blocking agent, NH₂OH. Thiazolidine-4-carboxylic acid and phosphate inhibited the enzyme and proline inhibited only at high concentrations. ATP, GTP, and CTP were all effective inhibitors of both the NADH- and NADPH-dependent activity. Phosphorylated nucleotide inhibition was reversed by Mg²⁺ ions.     

Enantiomers of 2-methyl- and 2,4-dimethyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylic acid: Preparation by resolution,determination of absolute configuration,and Curtius rearrangement

Both enantiomers of 2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylic acid 2 and 2,4-dimethyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylic acid 3 were prepared via resolution of the corresponding racemic carboxylic acids with (R)- and (S)-1-phenylethylamine, respectively. Absolute configuration of (−)-(R)-2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylic acid was determined by X-ray crystallography. Curtius rearrangement of acyl azides prepared from enantiomers of these heterocyclic carboxylic acids carried out in benzyl alcohol afforded enantiomers of the corresponding benzyl carbamates, which upon hydrogenolysis gave racemic 2-amino-2-methyl-3,4-dihydro-2H-1,4-benzoxazin-3-one 4 and 2-amino-2,4-dimethyl-3,4-dihydro-2H-1,4h-benzoxazin-3-one 5. Chirality 10:791–799, 1998. © 1998 Wiley-Liss, Inc.     

Effect of methoxyindole 2-carboxylic acid and 4-pentenoic acid on adipose tissue metabolism.

1. Administration of methoxyindole 2-carboxylic acid to rats caused an increase in circulating free fatty acids which was associated with rapid hypoglycemia in fasted rats and liver glycogenolysis without hypoglycemia in fed rats. 2. The incorporation of labeled glucose, pyruvate and acetate carbons into triacylglycerol-glycerol, triacylglycerol-fatty acids and CO2 was inhibited in epididymal fat pads from methoxyindole 2-carboxylic acid-treated rats and by the addition of methoxyindole 2-carboxylic acid in vitro. In contrast, palmitate esterification and oxidation were enhanced by methoxyindole 2-carboxylic acid. 3. The activity of enzymes associated with fatty acid synthesis was reduced to a varying degree in the presence of methoxyindole 2-carboxylic acid in the reaction mixture in concentrations lower than those used to inhibit glucose and pyruvate metabolism in the intact tissue in vitro. 4. 4-Pentenoic acid, a potent inhibitor of pyruvate and palmitate metabolism in the liver, was considerably less effective in adipose tissue. 5. The effect of the two hypoglycemic substances investigated on adipose tissue metabolism seems to be different.     

Bioactivation mechanism of L-thiomorpholine-3-carboxylic acid

L-Thiomorpholine-3-carboxylic acid (L-TMC) is a cyclized analog of S-(2-chloroethyl)-L-cysteine, which is cytotoxic in vitro and nephrotoxic in vivo. To determine whether L-TMC may play a role in S-(2-chloroethyl)-L-cysteine-induced toxicity, the cytotoxicity of L-TMC was studied in isolated rat kidney cells. L-TMC produced time- and concentration-dependent cytotoxicity. Probenecid, an inhibitor of the renal anion transport system, and L-alpha-hydroxyisocaproic acid, a substrate for L-amino acid oxidase, inhibited L-TMC-induced cytotoxicity. Rat kidney cytosol catalyzed the metabolism of L-TMC to a product absorbing at 300 nm. The increase in absorbance at 300 nm was accompanied by an increase in oxygen consumption and was inhibited by L-alpha-hydroxyisocaproic acid; moreover, the absorbance of the metabolite was quenched by addition of potassium cyanide or sodium borohydride, which indicated the formation of an imine. When L-TMC was incubated with rat kidney cytosol and sodium borodeuteride was added at the end of the incubation period, analysis by gas chromatography/mass spectrometry of the tert-butyldimethylsilyl ester of L-TMC showed the formation of [2H]TMC, indicating the intermediate formation of the imine 5,6-dihydro-2H-1,4-thiazine-3-carboxylic acid; chemically synthesized TMC imine showed similar behavior. The enzyme responsible for the metabolism of L-TMC was purified from rat kidney and was identified as L-amino acid oxidase. These observations indicate a role for L-amino acid oxidase in the bioactivation and cytotoxicity of L-TMC.     

1-Oxo-3-substitute-isothiochroman-4-carboxylic acid compounds: Synthesis and biological activities of FAS inhibition

A new series 1-oxo-3-substitute-isothiochroman-4-carboxylic acid compounds have been designed and synthesized. Screening of these molecules for FAS inhibition in vitro has indicated that compounds 2c and 2d showed more effective FAS inhibition activities and higher therapeutic index than C75.