Evaluation of New Tetra Substituted Pyrazolines for Their Antimicrobial and Antioxidant Activity; Structure-Activity Relationship

Abstract

A series of synthesized new 8-(5-aryl-4-octyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-yl)-octanoic acid ethyl esters 1 were evaluated in vitro for their antibacterial and antifungal activity against different organisms. The compounds were tested for their antioxidant activity and their reducing power ability. The structure-activity relationship of the compounds was described. I. Introduction The five membered heterocycles pyrazoles and their derivatives have flourished with considerable intensity because of their synthetic and biological applications. The literature review shows that pyrazoles have known to exhibit enormous biological activity such as antibacterial, antifungal, anti-inflammatory, anticonvulsant, hypoglycemic and anticancer activities. The pyrazoles possess antipyretic, antitumour, tranquilizing and herbicidal activities. Pyrazole derivatives are reported to exhibit antioxidant (1) and antimicrobial (2-4). A series of 3-substituted-5-hydroxy-5-trifluoro(chloro)methyl-1H-isonicotinoyl-4,5- dihydropyrazoles were synthesized and their in vitro antimicrobial activity was tested against INH susceptible mycobacterium tuberculosis H37Rv (5). Human body requires tats to function properly. Fatty acids serve as the components of more complex membrane lipids and as major components of stored fat in the body. Chemically, fatty acids and their esters are used in the synthesis of much class of compounds. 4,4-Dimethyl-2-oxazolines of fatty acids are useful derivatives for mass spectrometric analysis. The utility of these adducts for structural investigations of natural and artificial fatty acids is now well established (6). Recently Rai et al (7) reported the synthesis of 5-methyl-2- (5-methyl-1,3-diphenyl-1H-pyrazole-4-carbonyl)2,4-dihydro-pyrazol-3-ones and their antimicrobial and antioxidant activity. They also demonstrated the synthesis and antimicrobial activity of bis-heterocycles bearing pyrazoline and imidazole moieties (8). Pyrazolines obtained by the reaction of 4-acetyl thioanisole with aryl aldehydes through α,β-unsaturated ketones found to exhibit analgesic and anti-inflammatory activities (9). In view of the varied biological potency associated with pyrazole and their derivatives, a series of synthesized new tetra substituted pyrazolines (10) were considered for studying their biological activities. II. Materials And Methods The chemicals/reagents used were purchased from sigma-aldrich chemicals (India) and Merck Chemicals (India). In view of the biological potency associated with pyrazole derivatives, in the present investigation; the synthesized new 8-(5-aryl-4-octyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-yl)-octanoic acid ethyl esters 1 (10) were considered for studying their antifungal, antibacterial, antioxidant activities and their reducing power ability.