Synthesis of novel hetero ring fused pyridine derivatives; Their anticancer activity, CoMFA and CoMSIA studies.

A series of novel furo[2,3-b]pyridine-2-carboxamide 4a-h/pyrido[3',2':4,5]furo[3,2-d] pyrimidin-4(3H)-one derivatives 5a-p were prepared from pyridin 2(1H) one 1 via selective O-alkylation with α-bromoethylester followed by cyclization, then reaction with different aliphatic primary amines to obtain 4 and further reaction with triethyl orthoacetate/triethyl orthoformate. Also prepared novel furo[2,3-b]pyridine-2-carbohydrazide Schiff's bases 7a-h and pyrido [3',2':4,5]furo[3,2-d]pyrimidin-4(3H)-one derivatives 8a-h starting from furo[2,3-b]pyridine carboxylate derivatives 3 by reaction with hydrazine hydrate to form 6 and reaction with diverse substituted aldehydes and cyclization. Products 4a-h, 5a-p, 7a-h and 8a-h were screened against four human cancer cell lines (HeLa, COLO205, Hep G2 and MCF 7) and one normal cell line (HEK 293). Compounds 4e, 4f, 4g, 5h, 7c, 7d, 7e and 7f showed significant anticancer activity against all the cell lines at micro molar concentration and found to be non-toxic to normal cell line. Studies for HeLa, COLO205 and MCF-7 using CoMFA and CoMSIA. Models from 3D-QSAR provided a strong basis for future rational design of more active and selective HeLa, COLO205 and MCF-7 cell line inhibitors.

Studies on synthesis of novel pyrido[2,3-d]pyrimidine derivatives, evaluation of their antimicrobial activity and molecular docking.

A series of novel pyrido[2,3-d]pyrimidine derivatives 6 were prepared starting from 2-amino-3-cyano-4-trifluoromethyl-6-phenyl pyridine 3 via Grignard's reaction, cyclization followed by coupling with aliphatic and cyclic amines. All the compounds 6 were screened for antibacterial, minimum bactericidal concentration (MBC), biofilm inhibition activity as well as antifungal and minimum fungicidal concentration (MFC) activities. Among the screened compounds, the compounds 6e, 6f, and 6m which showed exhibiting promising activity have been identified. The results reveal that the compound pyrido[2,3-d]pyrimidine derivative 6e altered the sterol profile which may exert its antifungal activity through inhibition of ergosterol biosynthesis and could be an ideal candidate for antifungal therapy. The molecular docking results also validated the antifungal results.

Synthesis of novel ethyl 2,4-disubstituted 8-(trifluoromethyl)pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidine-9-carboxylate derivatives as promising anticancer agents.

A series of novel pyrido[2',3':3,4] pyrazolo[1,5-a]pyrimidine derivatives 6-9 were prepared in single step starting from 3-amino-6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridine-5-carboxylate 5 on reaction with symmetrical and unsymmetrical aliphatic and aromatic 1,3-diketones/α,ß unsaturated ketones/α,ß unsaturated keto ethers under conventional method. All the final compounds 6a-c, 8a-b and 9a-l were screened for anticancer activity against five human cancer cell lines such as PC-3 (CRL-1435), MDA-MB-231 (HTB-26), Hep G2 (HB-8065), HeLa (CCL-2) and normal HUVEC (CRL-1730). Compounds 8a, 9f and 9k which showed promising anticancer activity have been identified. Further, the promising compounds (8a and 9f) were able to inhibit the human topoisomerase I (TopI) activity similar to that of camptothecin.

Synthesis of novel nicotinohydrazide and (1,3,4-oxadiazol-2-yl)-6-(trifluoromethyl)pyridine derivatives as potential anticancer agents.

A series of novel nicotinohydrazide derivatives 6a-g and 1,3,4-oxadiazole functionalized pyridine derivatives 7a-k and 8a-d were prepared in series of steps. All the compounds were screened for cytotoxicity against HeLa (cervical), DU145 (prostate), HepG2 (liver) and MBA-MB-231 (breast) human cancer cell lines. Compounds 6h, 6i, 7d, 7h, 7i and 8b which showed promising cytotoxicity at <15µM concentration have been identified. Further optimization of the structure is underway to identify a lead compound.

Synthesis of novel hydrazone and azole functionalized pyrazolo[3,4-b]pyridine derivatives as promising anticancer agents.

A series of novel pyrazolo[3,4-b]pyridine based target compounds were synthesized starting from the key intermediate ethyl 2-(3-amino-6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-1-yl)acetate 5 on reaction with hydrazine hydrate followed by reaction with different aldehydes, acid chlorides and isothiocyanates to form hydrazones 7, oxadiazoles 8, 1,2,4 triazoles 10 and thiadiazoles 11 respectively in high yield. All the final compounds were screened for anticancer activity against four human cancer cell lines. Among them, 1,2,4 triazole derivatives showed promising activity and compound 10d is identified as a lead molecule.

Synthesis of novel triazole/isoxazole functionalized 7-(trifluoromethyl)pyrido[2,3-d]pyrimidine derivatives as promising anticancer and antibacterial agents.

A series of novel 1,2,3-triazole/isoxazole functionalized pyrido[2,3-d]pyrimidine derivatives 6a-c, 7a-h and 8a-e were prepared in series of synthetic steps. All the compounds screened for the anticancer activity against four human cancer cell lines using Nocodazole as standard. Compounds 7d and 7h showed highest activity against PANC-1 (pancreatic cancer) and A549 (lung cancer) cell lines respectively and more than standard. All the compounds also screened for antibacterial activity using Rifampicin and Ciprofloxacin as standards and identified promising compounds further evaluated for minimum inhibitory concentration to validate the data.

Synthesis of novel amide functionalized 2H-chromene derivatives by Ritter amidation of primary alcohol using HBF4·OEt2 as a mild and versatile reagent and evaluation of their antimicrobial and anti-biofilm activities.

A series of novel amide functionalized 2H-chromene derivatives 3 were prepared starting from ethyl-2-hydroxy-2-(trifluoromethyl)-2H-chromene-3-carboxylate 1 via sodium borohydride reduction followed by Ritter amidation using HBF4·OEt2 as a mild and versatile reagent. All the products 3 were screened for antimicrobial activity against various Gram-positive, Gram-negative bacteria and fungal strain. The promising derivatives such as 3f, 3g, 3k, 3l, 3m, 3n and 3o were further screened for minimum bactericidal concentration and bio-film inhibition activity and identified the potential ones. Among all the promising, compound 3g was more potent for antimicrobial, MBC and anti bio-film activities. The structure verses activity relationship of 3g revealed that the presence of two bromine atoms at sixth and R position promotes high activity.

Synthesis, cytotoxicity, antimicrobial and anti-biofilm activities of novel pyrazolo[3,4-b]pyridine and pyrimidine functionalized 1,2,3-triazole derivatives.

A series of novel pyrazolo[3,4-b]pyridine and pyrimidine functionalized 1,2,3-triazole derivatives 8a-g and 9a-g were prepared starting from 6-trifluoromethylpyridine-2(1H)one 2 via selective O-alkylation, followed by cyclisation using hydrazine hydrate to obtain 6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-3-amine 4. Compound 4 was diazotized followed by reaction with sodium azide, resulted in 3-azido-6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridine 5. Compound 5 was further cyclized with N-/O-propargylated pyrimidine derivatives under Sharpless conditions and obtained compounds 6 and 7, respectively. Each set of compounds 6 and 7 were alkylated with different alkyl halides and obtained respective products 8 and 9. All the products were screened for cytotoxicity against four human cancer cell lines such as A549-Lung (CCL-185), MCF7-Breast (HTB-22), DU145-Prostate (HTB-81) and HeLa-Cervical (CCL-2), compounds 9d, 9e and 9f which showed promising activity have been identified. The products were also screened for antimicrobial, anti bio-film and MBC activities. Promising compounds in each case have been identified.

Synthesis of novel 5-(3-alkylquinolin-2-yl)-3-aryl isoxazole derivatives and their cytotoxic activity.

The propargyl alcohol on reaction with aldoxime and NaOCl in DCM gave exclusively (3-arylisoxazol-5-yl) methanol 1. The compound 1 was oxidized to an aldehyde 2 followed by reaction with aniline resulted in Schiff's base 3. The compounds 3 were further reacted with various aldehydes having α-hydrogen using molecular iodine as catalyst and which yielded 5-(3-alkylquinolin-2-yl)-3-aryl isoxazole derivatives 4. All the final compounds 4 were screened against four human cancer cell lines (A549, COLO 205, MDA-MB 231 and PC-3) and among these compounds 4n showed potent cytotoxicity against all the cell lines at IC50 values of <12 µM.

Synthesis of novel 1,2,3-triazole/isoxazole functionalized 2H-Chromene derivatives and their cytotoxic activity.

A series of novel 2-(1,2,3-triazolylmethoxy) 5a-q and isoxazole tagged 6a-g 2H-Chromene derivatives were prepared starting from salicylaldehyde and ethyl-4,4,4-trifluoroacetoacetate via cyclization to form ethyl 2-hydroxy-2-(trifluoromethyl)-2H-Chromene-3-carboxylate 3. Compound 3 on reaction with propargyl bromide resulted compound 4 and was independently reacted with aryl/alkyl azides and aryl aldoximes obtained 2-(1,2,3-triazolylmethoxy) and isoxazole tagged 2H-Chromene derivatives 5a-q, 6a-i, respectively. Compounds 6 were further hydrolysed to acid derivatives 7a-g. All the products 5a-q, 6a-i, 7a-g were screened for cytotoxic activity against four human cancer cell lines and among all the compounds, 5f, 5g, 5l, 5q showed promising activity at <20 µM concentration.

Synthesis of novel 2-alkyl triazole-3-alkyl substituted quinoline derivatives and their cytotoxic activity.

The propargyl alcohol on reaction with alkylazides under Sharpless conditions through click chemistry concept gave exclusively 1,4-disubstituted triazoles 2. The compounds 2 were oxidized to aldehydes 3 followed by reaction with aniline resulted Schiff's bases 4. The compounds 4 was further reacted with various aldehydes having α-hydrogen using molecular iodine as a catalyst and obtained 2-alkyl triazole-3-alkyl substituted quinoline derivatives 5. All the final compounds were screened against four human cancer cell lines (THP-1, Colo205, U937 & HeLa) and promising compounds have been identified.

Synthesis of novel 4,6-disubstituted quinazoline derivatives, their anti-inflammatory and anti-cancer activity (cytotoxic) against U937 leukemia cell lines.

In view of the link between use of NSAIDs and altered cancer incidence and a growing evidence of COX-II implication in angiogenesis, a novel series of 4,6-disubstituted quinazoline derivatives have been synthesized starting from anthranilic acid derivatives 1 through conventional methods. Initially acylation followed by cyclisation to obtain benz-oxazinones 2 which on further treatment with ammonia yielded the crucial intermediate, 2-substituted benzamide (3). The products were subsequently cyclised to obtain quinazolones 4, chlorinated 5, then hooked to various optically pure alpha-amino acids to have 4,6-disubstituted quinazoline derivatives 6. All the derivatives 6 are screened for anti-inflammatory and anti-cancer activity against U937 leukemia cell lines. Some of the compounds exhibited promising anti-cancer activity with reference to standard drug Etoposide.

GdCl(3) catalysed Grieco condensation: a facile approach for the synthesis of novel pyrimidine and annulated pyrimidine fused indazole derivatives in single pot under mild conditions and their anti-microbial activity.

Indazole regioisomers such as 3-amino-4-(trifluoromethyl)-6-phenyl-1H-indazole-7-carbonitrile 1 and 3-amino-6-(trifluoromethyl)-4-phenyl-1H-indazole-7-carbonitrile 2 were independently reacted with formaldehyde followed by unsymmetrical, symmetrical and cyclic electron rich olefins in presence of GdCl(3) as catalyst and obtained pyrimidine fused indazole derivatives 3 and 4, respectively. The reaction is found to be concerted and an exclusive product is formed. Representative examples of compounds 3 and 4 were screened against Gram-positive, Gram-negative bacteria and fungal species such as yeast and filamentous fungi in vitro. Compound 3f showed significant activity against all species of Gram-positive and Gram-negative bacteria, whereas compounds 3h and 4a showed the least activity with reference to penicillin as well as streptomycin. Similarly compound 3c showed promising activity against yeast and filamentous fungi whereas compound 3f is inactive at the maximum concentration of 150 microg/mL.

Synthesis of novel pyrazolo[3,4-b]quinolinyl acetamide analogs, their evaluation for antimicrobial and anticancer activities, validation by molecular modeling and CoMFA analysis.

A series of novel alkyl amide functionalized 2,3-pyrazole fused quinoline derivatives 5, 6 and 7 have been prepared starting from quinoline-2(1H)one 1 in a series of steps. All the final products were screened for antibacterial activity, the promising lead compound 5r was identified with MIC values ranging between 3.9 and 7.8 µg/mL against different bacterial strains. Compound 5r also showed good antifungal and anti-biofilm activities against the tested panel of various fungal and bacterial strains. Compound 5r when treated on mature biofilms of S. aureus strain MLS16, showed increased levels of intracellular ROS accumulation suggesting its contribution to the bactericidal activity. All the compounds were also screened for anticancer activity against a panel of four human cancer cell lines. Based on these studies, compounds 5c, 5d, 5r and 7f were considered as promising and exhibited significant cytotoxicity with IC50 values of <15 µM. The biological activity data was further validated by molecular modeling and CoMFA studies.

Emergence of pyrido quinoxalines as new family of antimalarial agents.

A series of novel N-alkyl dihydro pyrido quinoxaline derivatives were synthesized using Gould-Jacobs reaction and evaluated their antimalarial activity in vitro against chloroquine sensitive (3D7) and drug resistant (Dd2) strains of Plasmodium falciparum. Among the compounds tested, 10 compounds were more potent than their structural standard analog ciprofloxacin, including 2 derivatives 5e and 5h, which showed 3.3-7.4 times more potency than ciprofloxacin against both the parasite strains. The results are encouraging and a lead molecule may emerge which is useful alone or in combination therapy.

Synthesis of novel 1,2,3-triazole substituted-N-alkyl/aryl nitrone derivatives, their anti-inflammatory and anticancer activity.

A series of novel 1,2,3-triazole substituted N-phenyl nitrone derivatives 5a-e were prepared in three steps starting from 1-substituted-1,2,3-triazole-4-carbaldehydes 2 via Schiff's base formation, reduction followed by oxidation. Similarly, 1,2,3-triazole substituted N-alkyl nitrone derivatives 6a-p were prepared in single step starting from compound 2 on reaction with N-alkyl hydroxylamine hydrochlorides. All the final compounds were screened for anti-inflammatory and anticancer activity against various cancer cell lines. Among the compounds tested, the compounds 5a, 5d, 6a, 6b, 6m and 6o exhibited significant inhibition of IL-1ß secretion as a measure of anti-inflammatory activity. Compound 5b, 5c, 6h, 6i and 6o exhibited significant activity against all the cell lines (A549, COLO 205, MDA-MB 231 and PC-3) at IC50 values of <15 µM.

Synthesis of novel alkyltriazole tagged pyrido[2,3-d]pyrimidine derivatives and their anticancer activity.

A series of novel alkyltriazole tagged pyrido[2,3-d]pyrimidine derivatives 5 and 6 was prepared starting from 2,3-active functional pyridine 1via cyclization, propargylation followed by reaction with alkyl or perfluoroalkyl azides under Sharpless conditions. All the compounds 5 and 6 were screened for anticancer activity against three cancer cell lines such as U(937), THP-1 and Colo205. The promising compounds 5b and 5e have been identified.

Click chemistry: studies on the synthesis of novel fluorous tagged triazol-4-yl substituted quinazoline derivatives and their biological evaluation--theoretical and experimental validation.

The formation of N- and O-propargylated quinazoline derivatives 2, 3 from quinazol-4-ones 1 was theoretically predicted by optimizations at B3LYP/6-31G* level, analysed kinetically and thermodynamically. Theoretical predictions are validated by experiment to observe the trends and found deviation. Thus, compound 1 was propargylated in basic media to obtain compound 2 and 3 in definite proportions. Each compound was further subjected to [3+2] cycloaddition using perfluoroalkyl azides through Click reaction under Sharpless conditions, and obtained a series of novel perfluoroalkyl-1H,1,2,3-triazol-4-yl substituted quinazolines 4, 5, and 6. All the compounds were screened for antimicrobial activity and identified potential compounds.

Synthesis and theoretical studies on energetics of novel N- and O- perfluoroalkyl triazole tagged thienopyrimidines--their potential as adenosine receptor ligands.

A series of novel N- and O- perfluoroalkyl triazole tagged thienopyrimidines 6a-c and 7a-d was synthesized in two steps from thienopyrimidin-4-ones 2 through O- and N-propargylated regioisomers 3a-i and 4a-i respectively. Compound 2 was reacted with propargyl bromide to form O- and N-propargylated regioisomers 3 and 4 in definite proportions. Each regioisomer was separated and independently subjected to [3+2] cycloaddition using perfluoroalkyl azides through Click reaction under Sharpless conditions and obtained exclusively anti product in each case. The formation of two regioisomers in the first step and single anti addition product in the next step could be explained based on computational studies carried out at B3LYP/6-31G(d) level of theory. Results of Fukui function indices at the reactive centers are in accordance with the observations. On evaluation of the synthesized molecules for their binding affinities towards adenosine receptors, 4d and 4f were found to be selective to A1 over A2A receptors.

Synthesis, anti-inflammatory evaluation and docking studies of some new fluorinated fused quinazolines.

A series of novel 8/10-trifluoromethyl-substituted-imidazo[1,2-c] quinazolines have been synthesized and evaluated in vivo (rat paw edema) for their anti-inflammatory activity and in silico (docking studies) to recognize the hypothetical binding motif of the title compounds with the cyclooxygenase isoenzymes (COX-1 and COX-2) employing GOLD (CCDC, 4.0.1 version) software. The compounds, 9b and 10b, were found to have good anti-inflammatory activity [around 80% of the standard: indomethacin]. The binding mode of the title compounds has been proposed based on the docking studies.