A new triazolothiadiazine derivative inhibits stemness and induces cell death in HCC by oxidative stress dependent JNK pathway activation

Hepatocellular carcinoma (HCC) is a highly heterogeneous cancer, and resistant to both conventional and targeted chemotherapy. Recently, nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to decrease the incidence and mortality of different types of cancers. Here, we investigated the cellular bioactivities of a series of triazolothiadiazine derivatives on HCC, which have been previously reported as potent analgesic/anti-inflammatory compounds. From the initially tested 32 triazolothiadiazine NSAID derivatives, 3 compounds were selected based on their IC₅₀ values for further molecular assays on 9 different HCC cell lines. 7b, which was the most potent compound, induced G2/M phase cell cycle arrest and apoptosis in HCC cells. Cell death was due to oxidative stress-induced JNK protein activation, which involved the dynamic involvement of ASK1, MKK7, and c-Jun proteins. Moreover, 7b treated nude mice had a significantly decreased tumor volume and prolonged disease-free survival. 7b also inhibited the migration of HCC cells and enrichment of liver cancer stem cells (LCSCs) alone or in combination with sorafenib. With its ability to act on proliferation, stemness and the migration of HCC cells, 7b can be considered for the therapeutics of HCC, which has an increased incidence rate of ~ 3% annually.

Design, Synthesis, and Biological Evaluation of Novel Triazolothiadiazoles Derived From NSAIDs as Anticancer Agents

BACKGROUND

Although transplantation, surgical resection, and tumor ablation are treatment options available following early diagnosis of HCC, their efficacy is restricted due to poor prognosis and high recurrence rates. Hence, small molecules with high selectivity and bioactivity are urgently required.

OBJECTIVE

This study presents the synthesis of a series of new triazolothiadiazole derivatives (1a-3j) with NSAID moieties and their cytotoxic bioactivities.

METHODS

The new synthetic derivatives (1-3; 1a-3j) and NSAIDs ibuprofen, naproxen, and flurbiprofen that commonly used in clinics were screened against human liver (Huh7), breast (MCF7), and colon (HCT116) carcinoma cell lines under in vitro conditions via NCI-sulforhodamine B assay.

RESULTS

The 4-methoxyphenyl substituted condensed derivatives 1h, 2h, and 3h were the most active compounds. Based on its high potency, compound 3h was selected for the further biological evaluation of hepatocellular carcinoma cell lines, and the mechanisms underlying cell death induced by 3h were determined. The results revealed that compound 3h induced apoptosis and cell cycle arrest in the sub G1 phase in human liver cancer cells.

CONCLUSION

These new small molecules may be used for the development of new lead compounds.

Synthesis, characterization, and in vivo pharmacological evaluation of novel mannich bases derived from 1,2,4-triazole containing a naproxen moiety

A new series of 1,2,4-triazole-5-thione Mannich derivatives containing a naproxen moiety (1a-o) was designed and synthesized to create naproxen analogs, with the aim of developing novel anti-inflammatory/analgesic agents with improved safety profiles. Target compounds were synthesized using classical Mannich reaction (i.e. one-pot three component condensation reaction), by reacting triazole molecule (1), formaldehyde, and diverse secondary amines in ethanol. The synthesized compounds were investigated using FT-IR, ¹H NMR, ¹³C NMR and mass spectroscopies, as well as elemental analysis. Compounds were then evaluated for their potential antinociceptive and anti-inflammatory activities using some validated invivo methods. Data obtained from acetic acid induced-writhing and carrageenan-induced paw edema tests revealed that all compounds induced peripherally-mediated antinociceptive activities, as well as notable anti-inflammatory effects. The results of hot-plate and tail-clip tests indicated that compounds 1a, 1b, 1c, 1d, 1g, and 1j have also centrally-mediated antinociceptive activities in addition to their peripherally-mediated effects. Molecular docking studies were performed to investigate the putative binding modes of the interactions between all compounds and COX-1/COX-2 enzymes using AutoDock Vina software. Docking of the compounds into the COX-2 active site produced binding interactions that are essential for COX-2 inhibitory activity. None of the compounds in the serial, except for 1m and 1j, induced significant gastrointestinal irritation. Overall, the results indicated that triazol Mannich bases bearing a naproxen moiety potentially represent a novel class of antinociceptive and anti-inflammatory agent with an improved gastric safety profile.

Abstract 995: A new thiadiazine derivative induces oxidative stress dependent JNK pathway activation and cell death in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common and the second lethal cancer worldwide. HCC is resistant to conventional chemotherapy and radiotherapy due to its highly heterogenous structure. Therefore, it is crucial to design and develop novel therapeutic strategies against HCC. Non-steroidal anti-inflammatory drugs (NSAIDs) have long been studied for the treatment of acute and chronic conditions with pain and inflammation. In recent years, evidence from various studies suggested that NSAIDs reduce the incidence and mortality of various types of cancers. Here, investigated the possible cytotoxic bioactivities of a series of triazolothiadiazine derivatives on HCC cells, which have been previously reported as potent analgesic/anti-inflammatory compounds. For this purpose, we first investigated the anticancer effect of our compounds bearing a triazolothiadiazine core. Initially, 30 compounds were tested against cancer cells. Among all the compounds, three of them (7a, 7b and 7c) showed noticeable cytotoxic activities within µM concentrations and were selected to be screened against a panel of HCC cell lines. Compound 7b was identified as a promising anti-cancer agent against liver cancer cells with cytotoxic doses (less than 5µM) assessed by both the SRB assay and RT-CES analysis and was analyzed with further in vitro and in vivo experiments to disclose the underlying mechanism of its action in HCC cells. Time- and dose- dependent growth inhibition upon treatment with compound 7b was observed due to cell cycle arrest at the G2/M phase and apoptosis. After detecting the activation of SAPK/JNK pathway, it was shown that ROS accumulation was triggering the downstream events and eventually apoptotic cell death. Furthermore, upon treatment with compound 7b, overall survival of xenografts increased, while the tumor size decreased compared to control groups. Additionally, we investigated the potential of this compound on liver cancer stem cell population (CD133+/EpCAM+) which are known to be responsible for drug resistance in HCC. Compound 7b was bioactive against LCSCs and decreased the ratio of CD133+/EpCAM+ population significantly in both Huh7 and Mahlavu cells. Altogether, the anti-tumor and anti-resistance effects of compound 7b approves that this small molecule can be considered as an anti-cancer agent for liver cancer therapeutics.

Citation Format: Deniz C. Kahraman, Ebru B. Guven, Birsen Tozkoparan, Rengul C. Atalay. A new thiadiazine derivative induces oxidative stress dependent JNK pathway activation and cell death in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 995.

Design and Synthesis of 1,2,4-Triazolo[3,2-b]-1,3,5-thiadiazine Derivatives as a Novel Template for Analgesic/Anti-Inflammatory Activity

Previously, we demonstrated that certain heterocyclic compounds derived from 3-substituted-1,2,4-triazole-5-thiones had promising analgesic/anti-inflammatory activities together with low ulcerogenic properties. Therefore, we sought to design and synthesize new derivatives of triazol-5-thiones-fused heterocycles. In the present study, a series of novel bis-Mannich bases, namely 2,6-disubstituted-6,7-dihydro-5H-1,2,4-triazolo[3,2-b]-1,3,5-thiadiazines (1a-d, 2a-c, and 3a-d), were synthesized and characterized to assess their possible anti-inflammatory/analgesic properties. Additionally, their ability to induce gastric toxicity was also evaluated. Several of the condensed compounds produced a degree of analgesic activity comparable to reference drugs in both the hot plate and tail-flick tests. A strong anti-inflammatory effect was observed for the derivatives carrying a benzyl group at the second position (2a-c). The majority of the prepared compounds caused comparatively less gastrointestinal (GI) side effects than the reference drugs naproxen and indomethacin did. These results showed that 1,2,4-triazolo[3,2-b]-1,3,5-thiadiazine derivatives might afford a safer alternative to currently available analgesic/anti-inflammatory agents for the treatment and management of inflammatory disease and pain.

Thiazolo[3,2-b]-1,2,4-triazole-5(6H)-one substituted with ibuprofen: novel non-steroidal anti-inflammatory agents with favorable gastrointestinal tolerance

In an effort to establish new candidates with improved analgesic and anti-inflammatory activities and lower ulcerogenic risk, a series of thiazolo[3,2-b]-1,2,4-triazole-5(6H)-one derivatives of ibuprofen were synthesized. All compounds were evaluated for their in vivo anti-inflammatory and analgesic activities in mice. Furthermore, the ulcerogenic risks of the compounds were determined. In general, none of the compounds represent a risk for developing stomach injury as much as observed in the reference drugs ibuprofen and indomethacin. The compounds carrying a 3-phenyl-2-propenylidene (1a), (biphenyl-4-yl)methylidene (1f) and (1-methylpyrrol-2-yl)methylidene (1n) at the 6th position of the fused ring have been evaluated as potential analgesic/anti-inflammatory agents without a gastrointestinal side effect. These new compounds, therefore, deserve further attention to develop new lead drugs.

Novel 3,6-disubstituted 7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines: synthesis, characterization, and evaluation of analgesic/anti-inflammatory, antioxidant activities

In this study, the synthesis of a new series of 3,6-disubstituted-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine 1a-4c compounds derived from 4-amino-3-substituted-1,2,4-triazole-5-thiones 1-4 is described. All of the synthesized compounds were screened for their possible analgesic / anti-inflammatory, antioxidant activities and gastric toxicity. The compound 2c was found to have both significant analgesic and consistent anti-inflammatory activity without inducing any gastric lesions along with minimal lipid peroxidation. A deep insight into the structures of the active compounds revealed that the compounds carrying an electron withdrawing group (a chloride or fluoride) on the phenyl ring at 6-position of the condensed heterocyclic derivatives exhibited noticeable higher activity.

Design and synthesis of some new thiazolo [3,2-b]-1,2,4-triazole-5(6H)-ones substituted with flurbiprofen as anti-inflammatory and analgesic agents

In the course of our ongoing studies, a series of thiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones substituted with flurbiprofen (CAS 5104-49-4) has been prepared. The compounds were synthesized by the cyclization of the 3-[(2-fluoro-4-biphenyl)ethyl]-5-mercapto-1,2,4-triazole (3) with chloroacetic acid and relevant benzaldehydes in the presence of acetic acid, acetic anhydride and anhydrous sodium acetate in one step. The product of this one-pot synthesis that precipitated on cooling of the reaction mixture was identified undoubtedly by X-ray crystallographic analysis as thiazolo[3,2-b]-1,2,4-triazole. In-vivo anti-inflammatory and analgesic activities of the compounds were assessed by carrageenan-induced hind paw edema and p-benzoquinone-induced abdominal constriction tests in mice, respectively. In addition, the ulcerogenic risks were evaluated. It is worthy of saying that the compounds which maintained analgesic/antiinflammatory activity of the starting compound were found to be safer with regard to gastric lesion risks at 100 mg/kg oral dose when compared with flurbiprofen. Among the synthesized compounds 3d showed the highest analgesic and antiinflammatory activity without inducing any gastric lesion and deserves further attention in order to develop new lead drug candidates.

Preparation of 5-aryl-3-alkylthio-l,2,4-triazoles and corresponding sulfones with antiinflammatory–analgesic activity

In this study, a series of 5-aryl-3-alkylthio-1,2,4-triazoles and corresponding sulfones were prepared with the objective of developing better analgesic-antiinflammatory compounds with minimum ulcerogenic risk. The structures of the compounds were elucidated by spectral and elemental analysis. The compounds were assayed per os in mice for their antiinflammatory and analgesic activity as well as the ulcerogenic risk and acute toxicity. Several of these compounds showed significant activity. Alkylsulfone derivatives were found to be much more potent analgesic-antiinflammatory agents than the corresponding alkylthio analogs. Compounds 9 and 11 were the most active of the series in both analgesic and antiinflammatory activity tests. In contrast to reference compound acetyl salicylic acid, these compounds did not induce gastric lesions in the stomach of experimental animals at the doses that exhibited analgesic/antiinflammatory activity.

Synthesis and evaluation of analgesic/ anti-inflammatory and antimicrobial activities of 3-substituted- 1,2,4-triazole-5-thiones

In this study, the synthesis of a novel series of Mannich bases of 5-mercapto-3-aryl-1,2,4-triazoles is described. The structures attributed to compounds la-5e were elucidated using IR and 1H-NMR spectroscopic techniques besides elemental analysis. The formation of 1-aminomethyl-3-substituted-1,2,4-triazole-5-thiones - not the isomeric 3-substituted-4-aminomethyl-1,2,4-triazole-5-thiones was unambiguously confirmed by X-ray crystallographic analysis of 1c. The compounds were examined for their in vivo anti-inflammatory and analgesic activity in two different bioassays, namely carrageenan-induced hind paw edema and p-benzoquinone-induced abdominal constriction tests in mice, respectively. In addition, the ulcerogenic effects of the compounds were determined. Among the tested derivatives most promising results were obtained for the compounds bearing a nonsubstituted phenyl group at C-3 position of the triazole ring (1a-e). The compounds were also evaluated for their in vitro antimicrobial activity against a series of gram positive bacteria [Staphylococcus aureus (ATCC 29213), Enterococcus faecalis (ATCC 29212)], gram negative bacteria [Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853)] and yeast-like microorganisms [Candida albicans (ATCC 90028), C. krusei (ATCC 6258), C. parapsilosis (ATCC 22019)]. One series of the examined compounds (3a-e) exhibited better antibacterial activity especially against gram positive bacteria than against gram negative bacteria. Compounds 2c, 3b, and 3e were found to be more effective against C. parapsilosis compared with the other derivatives (MIC: 16 microg/mL).

Protective effects of thiazolo[3,2-b]-1,2,4-triazoles on ethanol-induced oxidative stress in mouse brain and liver

A series of 3-[1-(4-(2-methylpropyl) phenyl) ethyl]-1 ,2,4-triazole-5-thione (I) and its bicyclic condensed derivatives 6-benzylidenethiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones (IIa-IIf) were investigated for the prevention of ethanol-induced oxidative stress in liver and brain of mice. Administration of ethanol (0.1 mL/mice, p.o.) resulted in a drop of total thiol groups (T-SH) and non-protein thiol groups (NP-SH), and an increase in thiobarbituric acid reactive substances (TBARS) in both liver and brain tissue of mice (p < 0.001). Among the compounds investigated (at a dose of 200 mg/kg, p.o.), I and IId ameliorated the peroxidative injury in these tissues effectively. Compounds IIa, IIc and IIe improved the peroxidative tissue injury only in brain. These findings suggest that certain condensed thiazolo-triazole compounds may contribute to the control of ethanol-induced oxidative stress in an organ selective manner.

Mechanistic Studies of Inactivation of Glutathione S-transferase Pi Isozyme by a Haloenol Lactone Derivative

Cancer chemotherapy often fails due to acquired drug resistance. One of the most critical biochemical changes observed in drug-resistant tumor cells is over-expression of glutathione S-transferase Pi isozyme (GSTP1). Glutathione S-transferase inhibitors have been used as potentiating agents of chemotherapeutic drugs. Earlier we reported haloenol lactone 1 as a site-directed GSTP1 inactivator. We proposed that enzymatic hydrolysis of the haloenol lactone may be the initial step of GSTP1 chemical modification, resulting in the inactivation of the enzyme. Enzyme inactivation is initiated through addition of Cys-47 to the lactone ring, which is opened in the process to form an alpha-bromoketone adduct. The acidity of Cys-47 confers good leaving group properties, and rapid hydrolysis occurs to generate an alpha-bromoketoacid intermediate. The reaction may proceed via alkylation of the transient thioester to form a six-membered ring episulfonium ion intermediate which would be yet more reactive toward hydrolysis, with either process leading to the observed mass increase of 230 Da. To probe the importance of the bromine of the lactone in GST inactivation, we designed and synthesized compound 2. Unlike lactone 1, lactone 2 did not show time-dependent inhibitory effect on GSTP1. Incubation of compounds 1 and 2 with excess of N-acetyl cysteine produced the corresponding di-N-acetyl cysteine conjugate and mono-N-acetyl cysteine conjugate, respectively. To probe the role of Cys-47 in the inactivation of GSTP1 by compound 1, we prepared mutant C47A GSTP1. The mutant GSTP1 still showed good activity toward CDNB, but it lost susceptibility to the inactivation by compound 1. In addition, LC-MS/MS technique allowed us to identify the modified Cys-47 after the enzyme was exposed to compound 1.

6-(2-Fluorobenzylidene)-2-[1-(2-fluoro-4-biphenyl)ethyl]thiazolo[3,2-b][1,2,4]triazol-5(6H)-one

The title compound, C(25)H(17)F(2)N(3)OS, was synthesized from 6-(benzylidene)thiazolo[3,2-b][1,2,4]triazol-5(6H)-one. The fused thiazolo[3,2-b][1,2,4]triazole system is essentially planar, and bifurcated C-H.O, C-H.N and C-H.F interactions are present between molecules.

Synthesis, characterization and antiinflammatory-analgesic properties of 6-(alpha-amino-4-chlorobenzyl)thiazolo [3,2-b]-1,2,4-triazol-5-ols

A series of 6-(alpha-amino-4-chlorobenzyl)-thiazolo[3,2-b]-1,2,4-triazol-5-ols (2a-j) were synthesized from 6-(4-chlorobenzylidene) thiazolo[3,2-b]-1,2,4-triazolo-5(6H)-one (2) by applying Michael addition reaction. All the compounds were characterized by their melting points, elementary analysis, IR and 1H-NMR spectra and screened for their anti-inflammatory and analgesic activities. Among the derivatives compound 2i bearing 4-(4-acetylphenyl)piperazine showed the highest and dose-dependent analgesic and anti-inflammatory activity without inducing any gastric lesion.

Synthesis of some 1,2,4-triazolo[3,2-b]-1,3-thiazine-7-ones with potential analgesic and antiinflammatory activities

Starting from 3-substituted-1,2,4-triazole-5-thiones (la-h), eight new 5-carbomethoxy-2-substituted-7H-1,2,4-triazolo[3,2-b]-1,3-thiazine-7-ones (2a-h) were synthesized and characterized by spectral and elementary analysis. The obtained compounds were submitted to preliminary pharmacological assay to evaluate their antiinflammatory and analgesic activities as well as gastrointestinal irritation liability and acute toxicity. Among the compounds studied, compounds 2c, 2d, 2e and 2h showed most remarkable antiinflammatory activity in the carrageenan and serotonin induced edema and in the inhibition of castor oil-induced diarrhea tests. The analgesic activity of these active compounds correlated with their antiinflammatory activities in the inhibition of acetic acid-induced writhing test. In gastric ulceration studies, the compounds were found safety at low dose levels (10 and 20 mg/kg).

Synthesis of some thiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones and their novel Michael addition products with anti-inflammatory activities

In this study, 21 new compounds having 2-methyl-6-benzylidenethiazolo[3,2-b]-1,2,4-triazol-5(6H)-one (2-4) and 2-methyl-6-(alpha-aminobenzyl)thiazolo[3,2-b]-1,2,4-triazole-5-ol (2a-4g) structures were synthesized. The structures of the compounds were proved by spectral and elemental analysis. All of the compounds synthesized were tested for their anti-inflammatory actively and ulcerogenic potential in mice at 10, 20 and 40 mg/kg dose levels. Compound 4b showed higher anti-inflammatory activity than the analogue derivatives and indometacin (CAS 53-86-1), used as a reference drug, at 10 mg/kg dose level. Generally, the compounds were found to be more reliable than indometacin since they did not cause any reaction in the stomach.

Studies on synthesis, chromatographic resolution, and antiinflammatory activities of some 2-thioxo-1,2,3,4-tetrahydropyrimidines and their condensed derivatives

In this study, the synthesis of some new 2-thioxo-1,2,3,4-tetrahydropyrimidines and their condensed derivatives, thiazolo[3,2-a]pyrimidines, are described. The structures of the compounds were confirmed by 1R, 1H-NMR, 13C-NMR, and mass spectroscopy. The direct high-performance liquid chromatographic separation of the compounds on derivatized cellulose chiral stationary phases such as cellulose tris(3,5-dimethylphenylcarbamate) (OD), cellulose tris(4-methylphenylcarbamate) (OG), and cellulose tris(4-methylbenzoate) (OJ) was studied. All of the compounds were screened for their antiinflammatory activity and also investigated histopathologically. Compounds 3 and 1a were found to be the most promising antiinflammatory agents in this group.

6-Benzylidenethiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones substituted withibuprofen: synthesis, characterization and evaluation of anti-inflammatory activity

In this study, the synthesis of 3-[1-(4-(2-methylpropyl)phenyl)ethyl]-1,2,4-triazole-5-thione (2) and its condensed derivatives 6-benzylidenethiazolo[3,2-b]-1,2, 4-triazole-5(6H)-ones (2a-u) are described. The structures of the compounds were elucidated by spectral and elemental analysis. In the pharmacological studies, anti-inflammatory activities of these compounds have been screened. Among the compounds examined, the compounds 2 and 2g possessed the most prominent and consistent activity. In gastric ulceration studies the synthesized compounds were generally found to be safe at a 200 mg/kg dose level.

Synthesis and evaluation of anti-inflammatory activity of some thiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones and their Michael addition products

Thiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones (4-10) were obtained in a one step synthesis by heating 3-aryl-5-mercapto-1,2,4-triazoles (3a-d) with chloroacetic acid and appropriate aromatic aldehyde in acetic acid and acetic anhydride in the presence of anhydrous NaOAc. Michael type addition of cyclic secondary amines (N-methylpiperazine, piperidine) to 4-10 gave 2-phenyl-6-(alpha-aminoarylmethyl)thiazolo[3,2-b]-1,2,4-triazole-5 -ols (4a-10b). The structures of the compounds were confirmed by spectral and elementary analysis. The compounds synthesized in previous and present studies were investigated for their anti-inflammatory activities.

Synthesis and anti-inflammatory activities of some thiazolo[3,2-a]pyrimidine derivatives

Sixteen new 2-benzylidene-7-methyl-3-oxo-5-(substituted phenyl)-2, 3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid methyl esters (1a-4d) have been synthesized by reacting 1,2,3,4-tetrahydropyrimidine-2-thiones (1-4) with chloroacetic acid and appropriate benzaldehydes in a single step. Their structures have been proved by IR, 1H NMR, mass spectra and elemental analysis. The compounds were tested for their anti-inflammatory activities. Test results revealed that compounds 1b, 1c, 4a and 4c exerted moderate anti-inflammatory activity at the 100 mg/kg dose level compared with indomethacin.

Condensed heterocyclic compounds: synthesis and antiinflammatory activity of novel thiazolo[3,2-alpha] pyrimidines

In this study, thirty six new 2-benzylidene-7-methyl-3-oxo-5- phenyl-2,3-dihydro-5H-thiazolo[3,2-alpha]pyrimidine-6-carboxylic acid methyl esters were synthesized and characterized by spectral, crystallographic, and elemental analysis. The antiinflammatory activity of the compounds was tested by the carrageenan hind paw edema test. It was found that compound 6a having a 2-meth-oxyphenyl group at position 5 and a benzylidene group at position 2 was the most potent compound in this series. All the compounds that were tested for ulcer activity gave positive results.

New thiazolo[3,2-a] pyrimidine derivatives, synthesis and calcium antagonistic activities

The synthesis of a series of thiazolo[3,2-a]pyrimidine derivatives were described. The structures of the compounds were elucidated by IR, 1H-NMR, 13C and elementary analysis. The compounds were evaluated for their calcium antagonistic activities using nifedipine as standard compound. All of the compounds were found to be less potent than nifedipine.

Synthesis of some 2-arylpropionic acid amides as prodrugs

The synthesis of amide prodrugs of some 2-arylpropionic acids (ibuprofen, naproxen, diclofenac and ketorolac) and the enantiomeric separation of these compounds are reported in this paper. The compounds were prepared from the corresponding 2-arylpropionic acids and (R-(-)-2-amino-1-butanol in the presence of N,N'-dicyclohexylcarbodiimide (DCC). Enantiomers were separated by preparative chromatography or crystallisation. The structure were confirmed by infrared, nuclear magnetic resonance and elementary analysis. The compounds prepared in the study have significant analgesic activity.

Synthesis of some thiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones as potential platelet aggregation inhibitors

Twenty new compounds having 2-methyl-6-benzylidenethiazolo[3,2-b]- 1,2,4-triazole-5(6H)-one (2a-d) and 2-methyl-6-(alpha-aminobenzyl)thiazolo-[3,2-b]-1,2,4- triazole-5-ol (5-20) structures were synthesized. Their structures were confirmed by elemental and spectroscopic analysis and their platelet aggregation inhibitory activities were investigated.