Synthesis of some triazolophthalazine derivatives for their anti-inflammatory and antimicrobial activities

Several novel series of triazolophthalazine derivatives namely; pyrazolylethenyltriazolophthalazinones (4a-d), styryltriazolophthalazinones (5a,b), aryloxopropenyltriazolophthalazinones (7a,b), pyrazolinyl- (8a,b), (9a,b) and (10a-f), pyrazolyl- (11a-d), (1,2-oxazol-5-yl)-1,2,4-triazolo[3,4-a]phthalazin-6(5H)-ones (14a,b), triazolo[3,4-a]phthalazin-3-yl-pyridine-3-carbonitriles (12a,b), triazolo[3,4-a]phthalazin-3-yl)ethylthioacetic acids (13a,b) and 2-aryl-5-arylamino-1H,5H-pyrazolo[2″,3″-1',5']imidazo[3',4'-1,5]-1,2,4-triazolo[3,4-a]phthalazin-12(13H)-ones (15a-c) have been synthesized. The anti-inflammatory activity of representative compounds has been studied. Compounds 8b, 10c, 10f, 11b, 12a, 13b, and 15a showed anti-inflammatory activities comparable to that of the reference standard, indomethacin. They exhibit also minimal ulcerogenic effect relevant to the reference standard and were found to be non-toxic up to 120 mg/kg orally or up to 75 mg/kg through parenteral route. Concerning the antimicrobial activity; compounds 12b and 13b were found to be equipotent to ampicillin against Staphylococcus aureus, while compounds 10a and 10f were found to be as potent as ampicillin against E. coli, whereas compound 14b exhibited equipotency to clotrimazole against Candida albicans. Compounds 8b, 10f, 11b, 12a, and 13b exhibited, besides their antimicrobial activity, moderate to potent anti-inflammatory profiles. This represents a fruitful matrix for the development of a new class of dual non-acidic anti-inflammatory/antimicrobial agents.     

Synthesis and biological evaluation of some hydroxypyrazole derivatives as anti-inflammatory-antimicrobial agents

Some hydroxypyrazole derivatives 2-7 were synthesized by cyclocondensation of the keto-ester 1 with hydrazines hydrate or substituted hydrazines followed by reduction and acylation with acetic anhydride or trifluoroacetic anhydride. The newly synthesized compounds were evaluated for their anti-inflammatory, antimicrobial activities. In addition, the ulcerogenic and acute toxicity profiles were determined. Compounds N-(4-(5-hydroxy-1-trifluoroacetyl-1H-pyrazol-3-yl)phenyl) trifluoroacetamide 4b, 3-(4-nitrophenyl)-1-(4-methoxyphenyl)-1H-pyrazol-5-ol 5b, and N-(4-(5-hydroxy-1-methyl-1H-pyrazol-3-yl)phenyl)trifluoroacetamide 7b were proved to be the most active anti-inflammatory, antimicrobial agents in the present study with a good safety margin and minimal or no ulcerogenic effect.     

Studies on 1,2,4-triazole derivatives as potential anti-inflammatory agents

The reaction of acetic or propionic acid hydrazides with various aryl/alkyl isothiocyanates gave thiosemicarbazides which furnished the 1,2,4-triazoles by alkali cyclization. The 4-aryl/alkyl-5-(1-phenoxyethyl)-3-[N-(substituted)acetamido]thio-4H-1,2,4-triazole derivatives were synthesized by reacting the triazoles with 2-chloro-N-(substituted)acetamide. The chemical structures of the compounds were elucidated by IR, (1)H-NMR, FAB(+)-MS spectral data and elemental analysis. In the pharmacological studies, anti-inflammatory activities of these compounds have been screened and significant activities were observed.     

Synthesis of beta-hydroxypropanoic acid derivatives as potential anti-inflammatory, analgesic and antimicrobial agents

A series of new 3-(substituted) 3-hydroxy-propanoic acid ethyl esters 1a-c, hydrazides 2a-c, thiosemicarbazides 3a-f, and semicarbazides 3g, 3h has been synthesized. Cyclization of compounds 3a-d in basic medium yielded 1,2,4-triazole-5-thiones 4a-d. On the other hand, reaction of hydrazides 2a-c with CS(2 )in basic medium afforded 1,3,4-oxadiazole-5-thiones 5a-c. All the synthesized compounds were characterized by their physical and spectral analyses data. The newly synthesized compounds were evaluated for their anti-inflammatory, analgesic, and antimicrobial activities. Compounds 1c, 3g, 4a, 4b, 4c, and 5c exhibited comparable anti-inflammatory activity to that of indomethacin and compounds 1c, 4c, and 5c were more analgesics than acetyl salicylic acid. Compounds 4b, 4c, and 5c showed superior GI safety profile (33.3%, 33.3% and 50.0% ulceration) than that of indomethacin (100% ulceration) at 100 mg/kg oral dose. Compounds 4b, 4c, and 5c were also non-toxic with a median lethal dose (LD(50)) up to 200 mg/kg. The antibacterial and antifungal screenings identified compounds 3c, 4b, 4d, 5a, and 5b as the most effective against a variety of tested microorganisms.     

Novel 3,3a,4,5,6,7-hexahydroindazole and arylthiazolylpyrazoline derivatives as anti-inflammatory agents

A novel series of 7-benzylidene-3, 3a, 4, 5, 6, 7-hexahydro-3-phenyl-2H-indazole substituted at the 2-position were synthesized. The reaction of 2, 6-bis-benzylidenecyclohexanone (1) with thiosemicarbazide in the presence of NaOH afforded a mixture of the 3-H, 3a-H trans 2 and cis 2a diastereoisomers which have been separated by fractional recrystallization. Interaction of the first intermediate 2 with substituted phenacyl bromides, aromatic aldehydes and chloroacetic acid in presence of a mixture of acetic acid and acetic anhydride, and 2, 3-dichloroquinoxaline yielded the corresponding 7-benzylidene-3, 3a, 4, 5, 6, 7-hexahydro-3-phenyl-2H-indazole derivatives substituted at the 2-position with 4-aryl-2-thiazolyl 3a, b, 5-arylidene-4, 5-dihydro-4-oxo-2-thiazolyl 4a, b and thiazolo[4, 5-b]quinoxalin-2-yl 5, respectively. Moreover, the other intermediates 3, 5-diaryl-1-thiocarbamoyl-2-pyrazolines 7a-d were reacted with the previously-mentioned reagents and gave the corresponding 3, 5-diaryl-1-(4-aryl-2-thiazolyl)-2-pyrazolines 8a-h, 3, 5-diaryl-1-(5-arylidene-4, 5-dihydro-4-oxo-2-thiazolyl)-2-pyrazolines 9a-d and 3, 5-diaryl-1-(thiazolo[4, 5-b]quinoxalin-2-yl)-2-pyrazoline derivatives 10a, b, respectively. Some of the newly prepared compounds were subjected to evaluation for their anti-inflammatory activity. The structures of the new compounds were confirmed by elemental analyses as well as (1)H-NMR, IR, and MS data.     

Synthesis and biological evaluation of some pyrazole derivatives as anti-malarial agents

Novel series of pyrazole derivatives were synthesized and tested for their in vivo anti‐malarial activity using mice infected with chloroquine sensitive P. berghei at a dose level of 50 µmol/kg. The most active compounds were further tested in vitro against chloroquine resistant (RKL9) strain of P. falciparum. The in vivo anti‐malarial activity study indicated that compounds 2a, 2b, 8a and 8b had mean percent suppression of 85%, 83%, 95% and 97%, respectively at equimolar dose level of the standard drug chloroquine diphosphate. Moreover, compounds 2a, 2b, 8a and 8b showed in vitro IC₅₀ values lower (p < 0.05) than that of the standard drug chloroquine phosphate (0.188 ± 0.003 µM) using the RKL9 strain. Compound 8b was the most active with IC₅₀ of 0.033 ± 0.014 µM. Generally, among the tested compounds, those containing a free carboxylic acid functional group on the pyrazole ring were the most active and this finding was supported by the docking results performed for the active compounds. The acute toxicity studies of the active compounds revealed that they have a good safety profile.     

Synthesis of 5-phenyl-1-(3-pyridyl)-1H-1,2,4-triazole-3-carboxylic acid derivatives of potential anti-inflammatory activity

A series of 5-phenyl-1-(3-pyridyl)-1H-1,2,4-triazole-3-carboxylic acid derivatives 4-10 were synthesized by rearrangement of 4-(3-pyridyl)-hydrazono-2-phenyl-2-oxazolin-5-one 3 in the presence of different nucleophiles to afford derivatives 4, 7, and 8, while hydroxamic acid derivative 6 was prepared from reaction of methyl ester 4 with hydroxylamine hydrochloride. Semicarbazide 9 and thiosemicarbazide 10, derivatives of the 5-phenyl-1-(3-pyridyl)-1H-1,2,4-triazole-3-carboxylic acid, were synthesized via hydrazide 8 with potassium cyanate and appropriate isothiocyanate, respectively. The structures of the synthesized compounds were confirmed by elemental analyses, IR, (1)H-NMR, and mass spectra. The results of the anti-inflammatory activity of the synthesized derivatives showed that most of the tested compounds 4-10 showed significant inhibition against carrageenan-induced rat paw edema in albino rats. Derivatives 4 and 8 showed promising results and were found to be equipotent or more potent than Indomethacin and Celecoxib as reference drugs at two dose levels, 5 and 10 mg/kg, and they have no ulcerogenic activity.     

Synthesis of some chalcones and pyrazolines carrying morpholinophenyl moiety as potential anti-inflammatory agents

Chalcones of 2a–f and their corresponding products, pyrazolines 3a–f , were synthesized and evaluated for their anti‐inflammatory activity against carrageenan edema in albino rats at a dose of 10 mg/kg. All the compounds of this series showed promising anti‐inflammatory activity. The most active compounds of this series, 2a , 2b , and 2d , were found to be most potent. They showed higher percentage of inhibition of edema than the standard drug indomethacin.     

Synthesis of novel 1-pyrazolylpyridin-2-ones as potential anti-inflammatory and analgesic agents

A new series of 4-alkyl/aryl-2-oxo-1-pyrazolyl-1,2-dihydropyridine-3-carbonitriles, pyrazolo[3,4-b]pyridine-5-carbonitriles and pyrido[2,3-d]pyrimidine-6-carbonitriles have been synthesized and tested for their anti-inflammatory and analgesic activities. Among the tested compounds, 3e and 8b exhibited comparable anti-inflammatory activity to the standard (indomethacin). Compounds 5, 7a, and 8b displayed potent analgesic activity. Detailed syntheses, spectroscopic and biological data are reported.     

Design and synthesis of some substituted 1H-pyrazolyl-oxazolidines or 1H-pyrazolyl-thiazolidines as anti-inflammatory-antimicrobial agents

Four series of 1 H-pyrazole derivatives have been synthesized. The first series was synthesized starting with the reaction of 3-(5-bromo-2-thienyl)-1-phenyl-1 H-pyrazole-4-carboxaldehyde 1 with L-serine, L-cysteine, or L-penicillamine, followed by N-protection using (Boc)(2)O to provide compounds 2. The latter compounds could be N-deprotected by 4N HCl/dioxane to afford the second series 3 or reacted with NH(4)OH in the presence of DCC/HOBt to give the corresponding amides 4 followed by N-deprotection giving rise to compounds 5. The newly synthesized compounds were evaluated for their anti-inflammatory-antimicrobial activities. In addition, the ulcerogenic and acute toxicity profiles were determined. Compound 5b (2RS, 4R)-2-[3-(5-bromo-2-thienyl)-1-phenyl-1H-pyrazol-4-yl]-5-methylthiazolidine-4-carboxamide, proved to be the most active anti-inflammatory-antimicrobial agent in the present study with a good safety margin and no ulcerogenic effect.     

Anti-inflammatory and gastro sparing activity of some new indomethacin derivatives

Indomethacin is a non-steroidal anti-inflammatory drug but its use is associated with high degree of gastric toxicity therefore it is prescribed only in severe conditions. In order to reduce the gastric toxicity of indomethacin, various oxadiazole, triazole, thiadiazole and triazine derivatives have been synthesized. Out of thirteen cyclized derivatives, eleven were screened for anti-inflammatory activity by Winter et al. method. Four compounds showed highly significant activity and were further tested for analgesic, ulcerogenic and lipid peroxidation activities. The tested compounds showed anti-inflammatory activities in the range from about 32% to 85% as compared to that of indomethacin of about 96%. The compounds showing high anti-inflammatory activity also exhibited reduction in severity index. These compounds also produced less malondialdehyde content in gastric mucosa than the standard drug indomethacin. The study showed that the compounds inhibited the induction of gastric mucosal lesions and it can be suggested from our results that their protective effects may be related to inhibition of lipid peroxidation in the gastric mucosa.     

Synthesis of certain 2-aminoadamantane derivatives as potential antimicrobial agents

N-(2-Adamantyl)-N'-(5-arylhydrazono-6-methyl-4-oxopyrimidin-2-yl) guanidines (IIIa, b), 2-(2-adamantyl-amino)-4-amino-s-triazine (IVa) and its 6-chloromethyl derivative (IVb) were prepared by cyclization of 1-(2-admantyl) biguanide HCl (I) with ethyl 2-arylhydrazono-3-oxobutyrates (II), ethyl formate and ethyl chloroacetate, respectively. Where 1-(2-adamantyl)-3-(4, 5-dioxo-2-imidazolidinylidene) guanidine (V) was used as intermediate for the synthesis of amides (VIIa, b), hydrazide (VIII) and azomethine derivatives (IXa, b) of alkyl 2-(2-adamantyl-amino)-4-amino-s-triazine-6-carboxylates (VI a, b). The antimicrobial testing of the prepared compounds proved that compound IXb was the most active. It showed a marked bacteriostatic effect againstStaphylococcus aureus andBacillus subtilis.     

Aminocarbonyl arylvinylbenzamides as gastric sparing anti-inflammatory agents

Some (E/Z)‐aminocarbonyl arylvinylbenzamides ( B1 – B15 ) were synthesized, evaluated for anti‐inflammatory activity and ulcerogenic tendency, and their effect on gastro‐intestinal motility in the rats was studied. These benzamides comprising of aliphatic unsaturated region situated between two amide linkages were synthesized by nucleophilic ring opening of appropriate azlactones ( AZ1 – AZ4 ) by suitable amines. The characterization of newly synthesized benzamides was performed by IR, ¹H‐ and ¹³C‐NMR, mass and elemental analysis. Amongst the tested compounds, benzamide B1 , B2 , B4 , B5 , and B13 were able to produce comparable or superior anti‐inflammatory activity at 10 and 20 mg/kg p.o. dose with respect to standard diclofenac in carrageenan induced rat paw edema model with lessened propensity to cause gastro‐intestinal hypermotility and were found to have nil tendencies to generate gastric ulcers.     

Novel thiazolyl,thiazolinyl and benzothiazolyl Schiff bases as possible lipoxygenase's inhibitors and anti-inflammatory agents

In continuation of our previous research, several new thiazolyl/thiazolinyl/benzothiazolyl Schiff bases have been designed, synthesized and identified. The referred compounds are reported to act as lipoxygenase inhibitors affecting inflammation and/or psoriasis. The compounds were screened for their reducing activity (with the stable free radical 1,1-diphenyl-2-picryl-hydrazyl, DPPH) and for inhibition of soybean lipoxygenase (LOX). Anti-inflammatory activity was examined in vivo using the carrageenin induced mice paw edema (32.6-75%). The results are discussed in terms of structural and physicochemical characteristics of the compounds. Compound 2d possessed the highest inhibition 75%.     

Synthesis and pharmacological evaluation of some 4-oxo-quinoline-2-carboxylic acid derivatives as anti-inflammatory and analgesic agents

The synthesis and the pharmacological activity of a series of 1-aroyl derivatives of kynurenic acid methyl ester (4-oxo-quinolin-2-carboxy methyl (KYNA) esters), structurally related to NSAID indomethacin are described. The derivatives were screened in vivo for anti-inflammatory and analgesic activities. Most of the compounds exhibited good anti-inflammatory and analgesic activities. An automatic docking of the synthesized compounds was performed using X-ray structures of COX-1 and COX-2. Docking results are in good accordance with the experimental biological data.     

Synthesis of some novel substituted purine derivatives as potential anticancer, anti-HIV-1 and antimicrobial agents

In search of novel purine antimetabolites, a series of 8-substituted methylxanthine derivatives was prepared in order to explore their in vitro anticancer, anti-HIV-1 and antimicrobial activities. The target compounds include: 8-[(3-substituted-4-oxo-thiazolidin-2-ylidene)hydrazino]-1,3-dimethyl (or 1,3,7-trimethyl)-3,7-dihydropurine-2,6-diones 5a-e, 8-[(3,4-disubstituted 2,3-dihydrothiazol-2-ylidene)hydrazino]-1,3,7-trimethyl-3,7-dihydropurine-2,6-diones 6a-d and 8-(5-amino-3-arylpyrazol-1-yl)-1,3-dimethyl- (or 1,3,7-trimethyl)-3,7-dihydropurine-2,6-diones 7a-g. The in vitro anticancer results revealed that compound 5d exhibited a super sensitivity profile towards leukemia K-562 with a GI(50) value of <0.01 microM. Compound 7c showed significant activity against colon cancer HCT-15 and renal cancer CAKI-1 (GI(50) values of 0.47 and 0.78 microM, respectively). Compound 7a displayed high activity against colon cancer HCT-15 (GI(50 )= 0.8 microM). The anti-HIV-1 results indicated that compound 6b displayed a good reduction of viral cytopathic effect (56.69%). The antimicrobial results showed that compound 5a was four times more active than ampicillin against P. aerugenosa (MIC =or< 25 microg/mL), compound 5b had twice the activity of ampicillin, while compounds 5d, 7c and 7f were equipotent to ampicillin. On the other hand, compound 7a was equipotent to ampicillin against P. vulgaris (MIC = 50 microg/mL).     

Synthesis of novel pyrazole and dihydropyrazoles derivatives as potential anti-inflammatory and analgesic agents

Novel dihydropyrazole 5-8, 10 and pyrazole derivatives 12, 14, 15, 17 were synthesized. The structures of the newly synthesized compounds were elucidated by spectral and elemental analyses. The anti-inflammatory activity of all new compounds was evaluated using the carrageenan-induced rat paw edema test using indomethacin and celecoxib as reference drugs. The most active derivatives as anti-inflammatory agents were accordingly tested for their analgesic activity using the p-benzoquinone-induced writhing method in mice and results revealed that these compounds had also good analgesic activity. The ulcerogenic liability of the selected compounds was also evaluated. Results showed that the selected derivatives had anti-inflammatory activity comparable to or slightly lower than the reference drugs, reaching about 82% inhibition with a considerable gastric safety profile.     

Synthesis of certain mercapto-and aminopyrimidine derivatives as potential antimicrobial agents

Reaction of ethyl 4-chloro-2-phenylpyrimidine-4-carboxylate (4) with 5-chloro-2-methylthiophenol or 3-aryl-4-phenyl-1,2,4-triazole-5-thiol yielded the corresponding thioethers (5) and (8a, b), respectively. Careful alkaline hydrolysis of (5) yielded the corresponding carboxylic acid (6). Reaction of (4) withp-aminoacetophenone yielded compound (10) which was reacted with certain aromatic aldehydes to afford the α, β-unsaturated ketones (11a–d). Condensation of (11a–d) with malononitrile or phenylhydrazine yielded the 2-amino-3-cyanopyridines (12a–f) or the 2-pyrazolines (13a, b), respectively. Seven representative compounds were tested for theirin vitro antimicrobial activity against some pathogenic micro-organisms, some of them were proved to be active.     

Novel pyrazole-clubbed thiophene derivatives via Gewald synthesis as antibacterial and anti-inflammatory agents

The aim of this study was to synthesize newer potent Schiff bases by condensing 2-amino-5-(2,4-dichlorophenyl)thiophene-3-carbonitrile and 1,3-disubstituted-1H-pyrazole-4-carbaldehydes, and to investigate their biological activity. The compounds were synthesized via Gewald synthesis and characterized by spectral data and elemental analyses. They were screened for their in vitro antibacterial and anti-inflammatory activities. The synthesized compounds were also evaluated for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv using the microplate Alamar Blue assay. Compounds 8b , 8c , 8f , 8g , 8k , 8n , and 8o showed promising antibacterial activity. The interactions between the substituted pyrazoles and bovine protein showed promising anti-inflammatory activity. The experimental results revealed compound 8a as a promising antitubercular agent. Hemolytic assays confirmed that the compounds are nontoxic, with percentage hemolysis ranging from 3.6 to 20.1, at a concentration of 1 mg/ml. The results suggest that the pyrazole ring and the substitution pattern on the heterocyclic moiety have an effect on the bioactivity.     

Medicinal chemistry of oxazines as promising agents in drug discovery

Oxazines have brought much synthetic interest due to their extensive biological activities. These are the important category of heterocycles, which may be formally derived from benzene and its reduction products by convenient substitution of carbon (and hydrogen) atoms by nitrogen and oxygen. In the last few decades, oxazine derivatives have documented as worthy synthetic intermediates and also blessed with notable sedative, analgesic, anticonvulsant, antipyretic, antimicrobial, antitubercular, antimalarial, antioxidant, and anticancer activities. Nowadays, it is important to develop new classes of compounds with more effective mechanisms due to drug resistance activity in which the ability of drug to effectively treat disease can be reduced. The aim of the article is to collect and make a more generalized review on the synthesis of oxazine derivatives and their pharmaceutical and biological activities. We hope this review will provide ample references for the researchers concerned with azines in generally and oxazines in particular.