Omprakash S. Yemul

Novel thiazolo-pyrazolyl derivatives as xanthine oxidase inhibitors and free radical scavengers.

Xanthine oxidase (XO) is a complex metalloflavoprotein, overproduction of which usually leads to a pathological condition called Gout. XO inhibitors may prove to be promising antigout agents. Present investigation describes synthesis, characterization and evaluation of 26 thiazolo-pyrazolyl derivatives V(a-z) for XO inhibitory and free radical scavenging activities. Derivatives Vq, Vo and Vh showed most promising XO inhibitory and free radical scavenging activities on the basis of their IC(50) values ranging from (6.5-9 μM). Significant dock scores compared with Allopurinol have been figured out using molecular docking. Evaluation of Vq, Vo and Vh for both the activities for first time may provide a new approach for antigout research.

Trisubstituted thiophene analogues of 1-thiazolyl-2-pyrazoline, super oxidase inhibitors and free radical scavengers.

Xanthine oxidase (XO) generates superoxide anions and H(2)O(2) for the self-defence system of organism. Abnormal production of this superoxides (reactive oxygen species) is responsible for a number of complications including inflammation, metabolic disorder, cellular aging, reperfusion damage, atherosclerosis and carcinogenesis. Series of novel trisubstituted thiophenyl-1-thiazolyl-2-pyrazoline libraries are synthesized containing 2,5-dichloro thiophene, 5-chloro-2-(benzylthio) thiophene and 5-chlorothiophene-2-sulphonamide, from chalcones in PEG-400 as green solvent. Superoxide (XO) inhibitory and free radical scavenging activities were also figured out with molecular modeling analysis, bearing in mind their possible future for super oxide inhibitor (Gout) therapeutics, compound 3k shows interesting superoxide inhibitory and free radical scavenger activity with IC(50)=6.2 μM, in comparison with allopurinol.

Green approach towards synthesis of substituted pyrazole-1,4-dihydro,9-oxa,1,2,6,8-tetrazacyclopentano[b]naphthalene-5-one derivatives as antimycobacterial agents

In the present communication, a simple and efficient synthesis of some new Pyrano-[2,3-c]-pyrazoles derivatives are described by the one-pot condensation of a mixture of 3-methyl-1-phenyl-1H-pyrazole-5(4H)-one, substituted heterylaldehydes and malononitriles in polyethylene glycol (PEG-400) as green reaction solvent, further reacted with substituted acetophenones in the presence of polyethylene glycol (PEG-400) to form naphthalene analogues. Synthesis of novel substituted naphthalene analogues libraries are currently of high interest. The chemical structures of newly synthesized compounds were confirmed by IR, 1H NMR and Mass spectral analysis. In vitro antimycobacterial activities of newly synthesized compounds were investigated against Mycobacterium smegmatis,Mycobacterium pheli and Mycobacterium tuberculosis species. The result revealed that most of the compounds showed good to moderate Antimycobacterial activity.

Bleaching earth clay (pH 12.5): a green catalyst for rapid synthesis of pyranopyrazole derivatives via a tandem three-component reaction

Efficient three-component synthesis of pyranopyrazole derivatives by reacting substituted aromatic aldehydes (1), (4-chlorophenyl)acetonitrile (2) and 3-methyl-1H-pyrazol-5(4H)-one (3) using bleaching earth clay (pH 12.5) as heterogeneous catalyst and PEG-400 as green solvent is reported in the present communication. The reaction time and product yields are excellent. Catalyst and solvent recovery and reusability are very good. This is a simple, green and rapid method for synthesis of pyranopyrazole derivatives.

“Green synthesis” of benzothiazepine library of indeno analogues and their in vitro antimicrobial activity

A novel series of indeno-benzothiazepine derivatives was synthesised via a “green” route. Synthesis of these compounds involves the treatment of dinucleophiles such as 2-aminobenzenethiols with α,β-unsaturated ketones in poly(oxyethylene) (poly(ethylene glycol), PEG-400) catalysed by acetic acid. The synthone α,β-unsaturated ketones were obtained by Claisen-Schmidt condensation of indan-1-one with substituted pyrazole-2-carbaldehydes prompted by bleaching earth (pH 12.5) as catalyst and PEG-400 as “green” reaction solvent. Screening of all the synthesised compounds for antimicrobial activity revealed that most of these compounds exhibited moderate to significant antimicrobial activity.

Green method for synthesis of 3-[2-(substituted-phenyl)-2-oxo ethylidene]-1,3-dihydro-indol-2-one and their in vitro antimicrobial activity

The cross-aldol condensation between isatin (I) and substituted acetophenone (IIa–e) in one-pot reaction afforded 3-[2-(substituted-phenyl)-2-oxo-ethylidene]-1,3-dihydro-indol-2-one using polyethylene glycol (PEG-400) as solvent and bleaching earth clay (pH 12.5) as a catalyst at room temperature. The PEG 400, bleaching earth are recyclable green solvent and catalyst, respectively. The formed compounds were confirmed by spectral analysis. These compounds show significant antimicrobial activity.

Eco-friendly waterborne coating from bio-based polyester amide resin

The vegetable oil-based waterborne polyurethane coatings have gained significant interest due to low volatile organic compounds, and hence, this has been considered as a proper substitute to the commonly used solvent-borne coating systems. In the present work, we have developed the polyurethane coatings from diethanolamide of fatty acid and dicarboxylic acid (sebacic acid and succinic anhydride)-based poly(esteramide) resin as a diol along with 2,2′-dimethylol propionic acid and isophorone diisocyanate. The chemical structure of bio-based diol and PU coatings was elucidated by FTIR and 1H NMR spectroscopy. The polyurethane dispersions (PUDs) prepared were analysed by particle size analysis and stability. The mahua oil-based PUDs were coated on the metal panels and the cured material obtained was characterized by the physico-mechanical, chemical resistance and the thermal properties which were compared with the petroleum resource-based PUDs. The PUD coatings showed good physico-mechanical properties, chemical resistance and thermal stability. Hence, the dispersion prepared from bio-based diols may find application as eco-friendly coatings.