In Vitro Evaluation of Antioxidant and Antimicrobial Activity of Series of New Pyrazole Derivatives; a Study on the Structure-activity Relationship

In present study, a series of new synthesized condensed pyrazole derivatives 1a-f have evaluated in vitro for their antioxidant activity, reducing power ability, antibacterial activity against Gram-positive and Gram-negative organisms and antifungal activity against different organisms. Minimum inhibitory concentration against the bacterial and fungal strains was determined. The study provides the structural impact of the compounds for their biological activity. INTRODUCTION: Free radicals play an important role in various pathological and xenotoxic effects so antioxidant may have protective role in these pathological conditions. Living organisms have antioxidant defense systems that protects against oxidative damage by removal or repair of damaged molecules . The term ‘antioxidant’ refers to the activity of numerous vitamins, minerals and phytochemicals which provide protection against the damage caused by ROS . Antioxidants interfere with the oxidative processes by scavenging free radicals, chelating free catalytic metals and by acting as electron donors . Resistance of pathogenic bacteria to available antibiotics is quickly becoming a major problem in the community and hospital based healthcare settings. Antimicrobials are one of the very important categories of drug. So it is quite clear from the spectrum of use that these categories of drugs are very important from medical point of view. But microbial resistance towards the drug creates a very serious problem; because of development of resistance, many drugs are now useless which were very effective before. Moreover, the toxic effects produced by these antibiotics are also reducing their significance . So there is need for new antimicrobial agents for resistant microbial infections. The chemistry of five membered heterocycles containing pyrazole moiety has flourished with considerable intensity because of their synthetic and biological applications. A number of pyrazole derivatives have been reported to act as antimycobacterial , anticancer , analgesics and antiinflammatory , antiepileptic , antihypertensive , ulcerogenic and lipid peroxidation properties . Pyrazole derivatives were known to possess potential antimicrobial, antioxidant activities and reducing power abilities 11-13 and antitumor activity .