Thesis On Coumarins

Thesis On Coumarins-7
Ethyl 2-oxo-2H-chromene-3-carboxylate was prepared by cyclization of salicylaldehyde with diethylmalonate in presence of catalytic amount of piperidine.Reaction of this ester compound with hydrazine hydrate in ethanol formed 2-oxo-2H-chromene-3-carbohydrazide.

Coumarins have been under extensive studies for their versatile biodynamic activities, for example coumarins with phenolic hydroxyl group have the ability to scavenge reactive oxygen species and thus prevent the formation of 5- HETE and 5- HHT in arachadonic acid pathway of suppression of inflammation.

Recent in vivo studies have revealed the role of coumarins in hepatotoxicity and also in depletion of cytochrome P450.

Similarly 1-azacoumarins which is part of quinoline alkaloids are known for their diverse biological activity and recently, a 6- functionalized 1-aza coumarins are undergoing human clinical trials as an orally active antitumor drug in view of its farnesyl protein-inhibiting activity in the nanomolar range.

Furthermore, several synthetic coumarins with a variety of pharmacophoric groups at C-3, C-4 and C-7 positions have been intensively screened for anti-microbial, anti-HIV, anti-cancer, lipidlowering, anti-oxidant, and anti-coagulation activities.

The synthesized compounds were tested in a standard disk diffusion assay and displayed strong to moderate antimicrobial activity, with a promising new lead prototype compound (7-amino-9-hydroxy-5-oxa-7a,8,11-triazacyclopenta[]phenanthren-6-one (5)) possessing greater activity that the antibiotics Ampicillin and Nystatin.

Antioxidant capacities of the compounds, determined spectrophotometrically using a phosphomolybdenum method, were greater, and in the case of compound 5 four times the activity of α-tocopherol acetate.some mannich base of 5-methyl-[(2-oxo-2H-chromen-3-yl) carbonyl]-2,4-dihydro-3H-pyrazol-3-one (Fig.20) by using conventional and non conventional (microwave) techniques.Most coumarins occur in higher plants, with the richest sources being the Rutaceae and Umbelliferae.Although distributed throughout all parts of the plant, the coumarins occur at the highest levels in the fruits, followed by the roots, stems and leaves.All the synthesized compounds showed activity against both gram positive and gram negative bacteria but lesser activity compared to standard drug. 9 Patel et al synthesized some 4-aryl-2,6-di(coumarin-3-yl)pyridines by the reaction of 3-coumarinoyl methyl pyridinium salts with1-[2H-1-benzopyran-2-on-3-yl]-3-aryl-prop-2-ene-1-ones in the presence of ammonium acetate and acetic acid under the Krohnke reaction conditions (Fig. All the synthesized compounds were screened for antimicrobial activity.None of the compounds showed activity against either in the coumarin nucleus or in the phenyl ring did not affect the antibacterial activity much more and all the compounds have the same activity.Activity of other compounds indicated that the presence of an additional fused benzene ring between the C-5` and C-6` positions inhibited the antibacterial activity towards ) compared to in Potato Dextrose Broth medium (PDB).Appropriate volumes of tested compounds were added to produce concentrations ranging from 10 to 100μg/m L. 12) and (Fig.13) showed good activity as antifungals compared to the antifungal ability of fluconazole, which was used as a standard drugs. 12 FIG.13 4-Heteroaryl-coumarin-3-carbaldehydes Streptomycin was used as standard anti-bacterial drug and ketoconazole was used as standard anti-fungal drug. 17) had activity equal to that of standard drug ketoconazole (31.25 μg/m L) against ntiinflammatory and analgesic activity: Parmar V et al synthesized 4-methyl coumarin derivatives 7,8-dihydroxy-3-ethoxycarbonyl methyl -4-methylcoumarin (DHEMC) and 7,8-diacetoxy-3 - ethoxycarbonylmethyl - 4 - methylcoumarin (DAEMC) (Fig.The one pot reaction preparation, spectral analysis, and molecular modeling experiments on the new 3,4-annelated coumarin systems with bioactivity associated structural features are described.These provided the insight into the equilibrium of the respective tautomeric forms making possible the reconciliation of previously published spectral data with the structure assignments as well as the correction of erroneously established structures.


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