Mohan Paul S. Ishar

Cytotoxic activity of 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones and 4-oxo-4H-chromene-3-carbothioic acid N-phenylamides.

6/6,7-Substituted-3-formylchromones (8a-g) were reacted with 2 equivalents thiobenzamide (9) in refluxing toluene to furnish substituted-3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones (10a-g) in high yields. Similarly, when substituted-2-anilino-3-formylchromones (8a-d) were reacted with thiobenzamide (9, 2 equivalents) in refluxing xylene, 4-oxo-4H-chromene-3-carbothioic acid N-phenylamides (11a-d) were obtained in high yields. All the compounds (10a-g) and (11a-d) display significant cytotoxic activity against a number of human cancer cell lines. Among these compounds 10e (IC(50) = 10 microM), 10b (IC(50) = 14.6 microM) and 10a (IC(50) = 10.5 microM) showed maximum cytotoxic activity on neuroblastoma. Also, the compound 10c (IC(50) = 10.5 microM) showed maximum cytotoxic activity on ovarian cancer cell line.

A versatile route to 2-alkyl-/aryl-amino-3-formyl- and hetero-annelated-chromones, through a facile nucleophilic substitution at C2 in 2-(N-methylanilino)-3-formylchromones

The N-methylanilino group in 2-(N-methylanilino)-3-formylchromones, obtained in high yield by rearrangement of C(4-oxo-4H[1]-benzopyran-3-yl)-N-phenylnitrones to 2-anilino-3-formyl-chromones followed by N-methylation, undergoes facile nucleophilic substitution by a variety of nitrogen nucleophiles, thereby paving the way for synthesis of a variety of novel 2-substituted-3-formylchromone derivatives as well as hetero-annelated chromones.

Mechanism of unusual formation of 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones and 4-oxo-4H-chromene-3-carbothioic acid N-phenylamides and their antimicrobial evaluation.

6/6,7-Substituted 3-formylchromones (9a-e) react with 2 equivalents of 2-phenyl-4-dimethylamino-1-thia-3-azabuta-1,3-diene (10) or thiobenzamide (11) in refluxing toluene to furnish novel substituted 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones (12a-e). However, reactions of substituted 2-anilino-3-formylchromones (15a-d) with thiobenzamide (11, 2 equivalents) in refluxing xylene furnish 4-oxo-4H-chromene-3-carbothioic acid N-phenylamide (17a-d) in high yields. A mechanistic rationalization of the conversion of 2-anilino-3-formylchromones (15a-d) to N-phenylamides (17a-d), and 3-formylchromones (9a-e) to the corresponding thioaldehydes, is proffered. All the compounds (12a-e, 17a-d) display very high antifungal and antibacterial activities against a number of strains. Dithiazole 12d exhibits a very high antifungal activity (MIC 5 microg/ml) against Geotrichum candidum, better than fluconazole (MIC 09 microg/ml) and also possesses good antibacterial activity (MIC 52 microg/ml) against Shigella flexneri.

Ameliorative effect of the cinnamon oil from Cinnamomum zeylanicum upon early stage diabetic nephropathy.

The current study was designed to evaluate the ameliorative effect of the cinnamon oil upon early stage diabetic nephropathy owing to its antioxidant and antidiabetic effect. Cinnamon oil was extracted by hydro-distillation of the dried inner bark of Cinnamomum zeylanicum Blume. Further characterization of the extracted oil was carried out using IR, (1)H-NMR, and (13)C-NMR techniques. Early stage of diabetic nephropathy was induced by administration of alloxan (150 mg/kg, I. P.). Cinnamon oil was administered at varying doses (5, 10, 20 mg/kg; I. P.) while the level of fasting blood glucose, total cholesterol, high density lipoprotein, urea, thiobarbituric acid reactive substances, reduced glutathione, and catalase were determined. These parameters in cinnamon oil treated groups were compared with those of standard (glipizide; 10 mg/kg) and vehicle treated groups in order to investigate if cinnamon oil confers a significant protection against diabetic nephropathy. Histological studies of the kidney proved the protective effect of cinnamon oil by reducing the glomerular expansion, eradicating hyaline casts, and decreasing the tubular dilatations. Our results indicate that the volatile oil from cinnamon contains more than 98 % cinnamaldehyde and that it confers dose-dependent, significant protection against alloxan-induced renal damage, the maximum decrease in fasting blood glucose having been achieved at the dose of 20 mg/kg.

Investigations on Peri-, Regio- and Stereoselectivities in Thermal Cycloadditions Involving C -(4-Oxo-4 H [1]benzopyran-3-yl)- N -phenylnitrones: Role of Steric Factors and Secondary Interactions in 1,3-Dipolar Cycloadditions

Abstract Complete peri-, regio- and stereoselectivities in thermal reactions of C-(4-oxo-4H[1]benzopyran-3-yl)-N-phenylnitrones with both electron-rich and electron-deficient olefins have been investigated. This conjugated nitrone undergoes frontier-orbital (LUMO-dipole HOMO-dipolarophile) controlled exo-selecitve 1,3-dipolar cycloadditions; the stereo-chemical outcome is influenced predominantly by steric factors, besides secondary orbital and/or polar interactions.

2-(N-Methylanilino)-3-formylchromone: a versatile synthon for incorporation of chromone moiety in a variety of heterocyclic systems and macrocycles through reactions with bifunctional nucleophiles

Abstract Reactions of 2-(N-methylanilino)-3-formylchromones with a number of bifunctional nucleophiles, involving substitution of N-methylanilino moiety and/or condensations with 3-formyl function have provided an easy access to a variety of potentially biologically active hetero-annelated chromones, novel macrocycles, and tetradentate ligands having intact chromone moiety.

Thermal rearrangements of C-(4-Oxo-4H[1]benzopyran-3-yl)-N-phenylnitrone-a route to novel quinolino[2,3-b]chroman-12-ones

Abstract C-(4-Oxo-4 H [1]benzopyran-3-yl)- N -phenylnitrones ( 1a-c ) undergo facile rearrangements on refluxing in benzene, yielding 2-( N -phenylamino)-4-oxo-4 H [1]-benzopyran-3-carboxaldehydes ( 2a-c , 70%) and 3-(phenyliminomethylene)-chroman-2,4-diones ( 3a-c , 25%). 2a-c undergo cyclization on refluxing with anhydrous AlCl 3 in dry CCl 4 followed by treatment with sulfuric acid, to give novel quinolino[2,3- b ]chroman-12-ones( 4a-c ) in 90% yield.

Anticonvulsant activity of schiff bases of 3-amino-6,8-dibromo-2-phenyl-quinazolin-4(3H)-ones

Schiff bases (9a-l) of 3-amino-6,8-dibromo-2-phenyl-quinazolin-4-(3H)-ones (8) with various substituted aldehydes were obtained by refluxing 1:1 molar equivalents of the reactants in dry ethanol for 6 h. The aminoquinazoline (8) was inturn obtained from 3,5-dibromoantharlinic acid via intermediate (7). All the synthesized compounds (9a-l) were evaluated for their anticonvulsant activity on albino mice by maximal electroshock method using phenytoin as a standard. The compound (9l) bearing a cinnamyl function displays a very high activity (82.74 %) at dose level of 100 mg/kg b.w.

Tandem reorganisation of 1,3-dipolar cycloadducts of C-(4-oxo-4H[1]benzopyran-3-yl)-N-phenylnitrone and allenic esters, leading to novel functionalized benzo[b]indolizines

Abstract C-(4-oxo-4 H [1]benzopyran-3-yl)- N -phenylnitrone ( 1 ) adds regiospecifically to the C 2 C 3 π-bond of allenic esters ( 2a-c ) and the 1,3-dipolar cycloadducts formed undergo a series of intramolecular reorganisations including an intramolecular (4+2) cycloaddition, in situ , to yield novel functionalized benzo[ b ]indolizines ( 3a-c ), in good yields.

Synthesis of β-ionone derived chalcones as potent antimicrobial agents.

A series of chalcones (3a-v) have been synthesized by condensation of β-ionone (1) with a variety of aldehydes (2a-v). The synthesized compounds have been screened for their in vitro antimicrobial activity against five bacterial and five fungal strains, using disc diffusion assay. The evaluated compounds display a wide range of activities, from completely inactive to the highly active compounds. Some of the compounds are also active against methicillin resistant staphylococcus aureus (MRSA).