Anees Pangal et al. Int. Res. J. Pharm. 2013, 4 (8) Page 172 INTERNATIONAL RESEARCH JOURNAL OF PHARMACY www.irjponline.com ISSN 2230 – 8407 Research Article SYNTHESIS, CHARACTERIZATION AND STUDY OF ANTIMICROBIAL ACTIVITY OF 2,6-DITERTIARY BUTYL-1,4-BENZOQUINONE HYDRAZONES Anees Pangal, Khursheed Ahmed* and Sajid Shaikh Dept. of Chemistry and Post Graduate Centre, Abeda Inamdar Sr. College of Arts, Science and Commerce Camp, University of Pune, Pune, India *Corresponding Author Email: aagpan@gmail.com Article Received on: 10/06/13 Revised on: 01/07/13 Approved for publication: 11/08/13 DOI: 10.7897/2230-8407.04834 IRJP is an official publication of Moksha Publishing House. Website: www.mokshaph.com © All rights reserved. ABSTRACT Four 2,6-di-tert-butyl-1,4-benzoquinone hydrazones have been synthesized viz. A1, A2, A3 and A4. The purity was checked using HPLC. These compounds were characterized by FTIR and H 1 -NMR and they shows a prominent absorption of -(C=N-) in FTIR. It also shows a common peak of oleifinic proton at 6.50 Hz. These hydrazones were tested for their antimicrobial activity against Gram +ve and Gram –ve bacteria. A3 was found to be active at a minimum concentration of 50 μg·mL –1 where as A2 was inactive. Keyword: Hydrazones, 2,6-Di-tert-butyl-1,4-benzoquinone, antimicrobial activity, Hydrazone derivatives. INTRODUCTION Benzoquinones are the compounds with important biological functions in oxidative phosphorylation and electron transfer processes 1 , bioenergetic transport 2,3 . They possess diverse pharmacological properties such as anti-inflammatory 4 , antimicrobial 5,6 , antiviral activities 7 and anticancer 8-11 . The compounds are used in the design and synthesis of various heterocyclic drug molecules as potential synthetic building blocks. The importance of research on these compounds in recent years is provided by the discovery of chemo preventive and therapeutic properties observed for a naturally occurring benzoquinone compound, viz. Thymoquinone, which is found in the Black Cumin (Nigella sativa) seed oil 12 . The black cumin seeds are being used as a spice in the Mediterranean region and in Western Asian countries including India. This herb is known by many different names such as ‘Kalonji’ in India ‘Panacea’ in Latin, ‘Habbah Sawda’ in Arabic, or ‘Hak Jung Chou’ in Chinese. The extracts of this plant have indicated potent antitumor activities without serious toxic effects suggesting that compounds having benzoquinone nucleus may be developed into useful therapeutic agents 13 . Most of the investigations on the biogenesis of benzoquinones have been reported with moulds such as Aspergillus fumigatus and Pencillium patulum 14 . Benzoquinones are the simplest structural quinines which are widely distributed in plants, animals and bacteria. Majority of the fungal benzoquinones are formed by the acetatemalonate pathway yielding ubiquinones having polyprenyl side chains 15 . These compounds are found in most aerobic organisms from bacteria to higher plants and animals and are involved in mitochondrial electron transport chains. The Streptomyces bacteria also produce large number of nitrogen containing heterocyclic quinones 16 . Radio-labelled precursor studies have indicated two biosynthetic routes for the formation of benzoquinone compounds which serve as important toxic defense for many insects and arthropods such as methylbenzoquinone, 2, 3-dimethyl and 2, 5- dimethylbenzoquinone. Comparatively less is known about the biogenesis of benzoquinones in higher plants 17 . The methods employed to isolate naturally occurring benzoquinones are common to natural products chemistry and involve sequential extraction with solvents of increasing polarity while the appropriate fractions are purified by column or thin layer or preparative thin layer chromatography. Ultrasonic or critical fluid extractions carried out in recent years offer advantages in terms of avoiding residual solvent levels 18 . Chemically 1, 4- benzoquinone is a multi-functional moiety exhibiting properties of a ketone, oxidant and an alkene undergoing addition reactions. It is a simple six-membered, non-aromatic compound which is the oxidised derivative of 1, 4- dihydroquinone. It can be easily reduced to 1, 4-benzenediol . Equimolar mixture of 1, 4-benzoquionone and 1, 4- benzenediol which is used as a standard electrode material is known as quinhydrone 19 . Several features make it an attractive motif for building supramolecular assemblies which are associated with the quinonoidal structure. Similarly, the quinonoidal carbonyl groups are capable of evolving hydrogen bonded assemblies yielding inclusion compounds 20,21 . The electron deficient benzoquinone system also yields charge transfer complexes very easily 22-27 . The facile redox cycling associated with benzoquinones makes them excellent oxidizing agents 28 . They are known to react with acetic anhydride and sulphuric acid to give triacetate of 1, 3, 4-trihydroxybenzene and the reaction is known as Thiele reaction 29 . They react with large number of primary and secondary aliphatic or aromatic amines yielding mostly disubstituted compounds. The benzoquinones easily undergo nucleophilic addition reactions and serve as an excellent dienophiles in the Diels- Alder reaction. However, single substitution is observed with secondary amines under selected conditions. During such substitutions one or two moles of reduced benzoquinone molecules are also formed as shown in Figure 1 30 . Harley-Mason and Laird 31 have reported on the formation of 1, 2, 3, 4-tetrahydro-1, 4, 5, 8-tetra- azaanthracene after reacting 2, 5-dihydroxy-p-benzoquinone with ethylenediamine in presence of air in aqueous media. A similar reaction with 2,3-dimethoxy-p-benzoquinone and ethylenediamine yields 2, 5-bis(2-hydroxyethylamino)-3, 6- dichloro-1, 4-benzoquinone which on further heating for several hours gives tetra-aza-anthracene Figure 2 32 . Aromatic amines also undergo nucleophilic substitution at 2 and 5