PYRAZOLE AND ITS BIOLOGICAL ACTIVITY

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ABOUT AUTHORS:
Vishwanadham Yerragunta*1, Duggi.Suman1, Kumara swamy1, V.Anusha1, Pratima Patil1, M. Naresh2
Department of Pharmaceutical Chemistry,
1Malla Reddy College of Pharmacy, Maisammaguda, Secunderabad-500014, A.P.
2Bharath Institute of Technology Pharmacy-Ibrahimpatnam, AP.
*vishwanadham.y@gmail.com

ABSTRACT:
The aim of this review is to provide an overview of diverse pharmacological activities of pyrazole moiety. Pyrazole are well known and important nitrogen containing 5-membered heterocyclic compounds and various methods have been worked out for their synthesis. Pyrazole chemically known as 1, 2-diazole has become a popular topic due to its manifold uses. Numerous pyrazole derivatives have been found to possess a broad spectrum of biological activities, which stimulated the research activity in this field. Pyrazoles and its derivatives represent one of the most active classes of compounds, which possess wide range of biological activities like anti-bacterial, anti-convulsant, analgesic, anti-microbial, anti-inflammatory, ant diabetic, sedative anti-rheumatic, anticancer, and anti-tubercular activities. The purpose of this review was to collate literature work reported by researchers on pyrazole for their various pharmacological activities and also reported recent efforts made on this moiety.

REFERENCE ID: PHARMATUTOR-ART-2073

PharmaTutor (ISSN: 2347 - 7881)

Volume 2, Issue 1

Received On: 29/11/2014; Accepted On: 07/12/2014; Published On: 15/01/2014

How to cite this article: V Yerragunta, D Suman, K swamy, V Anusha, P Patil, M Naresh, Pyrazole and Its Biological Activity, PharmaTutor, 2014, 2(1), 40-48

INTRODUCTION:
The chemistry of pyrazoles has been extensively investigated in the past. Pyrazoles are five member ring heterocyclic compounds, have some structural features with two nitrogen atoms in adjacent position and are also called as azoles1.


The chemical reactivity of the pyrazole molecule can be explained by the effect of individual atoms. The N-atom at position 2 with two electrons is basic and therefore reacts with electrophiles. The N-atom at position 1 is unreactive, but loses its proton in the presence of base. The combined two N-atoms reduce the charge density at C3 and C5, making C4 available for electrophilic attack. Deprotonation at C3can occur in the presence of strong base, leading to ring opening. Protonation of pyrazoles leads to pyrazolium cations that are less likely to undergo electrophilic attack at C4, but attack at C3 is facilitated. The pyrazole anion is much less reactive toward nucleophiles, but the reactivity to electrophiles is increased2

Pyrazoles are aromatic molecules due to their planar conjugated ring structures with six delocalized π-electrons. Therefore, many important properties of these molecules were analyzed by comparing with the properties of benzene derivatives3. Like other nitrogen involving heterocycles, different tautomeric structures can be written for pyrazoles. unsubstituted pyrazole can be represented in three tautomeric forms4.

Tautomeric forms of unsubstituted pyrazole.

Now a day’s vast number of compounds with pyrazole nucleus have been reported to show a broad spectrum of biological activity including. antimicrobial5, antiviral6, anti-tumor7,8, anti-histaminic9, anti-depressant10, insecticides11 and fungicides11. Due to its wide range of biological activity, pyrazoles ring constitutes a relevant synthetic route in pharmaceutical industry. In fact, such a heterocyclic moiety represents the core structure for number of drugs

LITERATURE:
· Eman M. Flefel et.al have reported the new substituted pyrazole, thiazole, and 1, 2, 4-triazole derivatives were synthesized. The sugar hydrazones, their acetylated derivatives as well as their derived acyclic C-nucleoside analogs, and the thioglycosides of the 1, 2, 4-traizole derivatives were also prepared. The antitumor activity of some of the synthesized compounds were studied, and a number of the tested compounds showed significant activities12.


· Mohamedsalahk.youssef et.al., have synthesized Ethyl 7-amino-3-(3-methyl-5-oxo-1-phenyl-2-pyrazolin-4-yl)-5-aryl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate was synthesized by the reaction of 4-(2-aminothiazol-4-yl)-3-methyl-5-oxo-1-phenyl-2-pyrazoline with arylidene ethyl cyanoacetate and it transformed to related fused heterocyclic systems via reaction with various reagents13.


· Rao Jyothi et al., have synthesized a novel series of 1, 3, 5-trisubstituted pyrazoles by the cyclo condensation reaction of chalcones and substituted hydrazides by irradiation under microwave energy and also by conventional method. Compound 3g showed good activity against E. coli and P.aerugiosa. Compound 3j showed good activity against the fungus A. fumigatus14.


· Sagar K. Mishra et al., have reported the synthesis of a series of 1- (2, 4-dinitrophenyl)-3-(3-nitrophenyl)-5-(4-substituted phenyl)-2-pyrazolin-4-ones by the oxidation of 1-(2, 4-dinitrophenyl)-3-(3-nitrophenyl)-5-(4-substituted phenyl) - 4-bromo-2-pyrazolines with dimethyl-sulfoxide and assayed for in vitro antimicrobial activity. Most of the synthesized compounds did not exhibit significant inhibitory activity against the tested strains15.


· SatheeshaRai N and BalakrishnaKalluraya et.al., have reported novel series of nitrofuran containing 1,3,4,5 tetra substituted pyrazole derivatives. Compound 3b showed highest anti-bacterial and antifungal activity than all other compounds16.


· Sahu SK et al., have synthesized a series of novel 4-(5-substituted aryl-4, 5-dihydropyrazole-3-yl-amino) phenols by treating substituted aryl-N-chalconyl amino phenols with hydrazine hydrate. It was observed increase in analgesic, anti-inflammatory and anti -microbial activities are attributed to the presence of 4-NO2, 2-OH and 4-Cl in phenyl ring at 5-position of pyrazoline ring of synthesized compounds17.


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