1. INTRODUCTION:

Benzimidazole is heterocyclic aromatic organic compounds formed by the fusion of benzene and imidazole rings. In medicinal chemistry it is an important pharmacophore structure. The use of Benzimidazole dates many years back for Study of Structural modifications and their pharmacological actions ^[1]. Moreover benzimidazole is a structural unit of naturally occurring nucleotide, due to which it easily interacts with the biopolymers of living system. This character is responsible for its numerous biological aspects like antihelminthic, antifungal, anti-allergic, antimicrobial, antiviral and antineoplastic activities. Since proteases have been linked with several disease states, including thrombosis, inflammation, bronchoconstiction and tumor growth and invasion. The incorporation of the nucleus is an important synthetic strategy in studies of antimicrobial drug discovery ^[2]. This review highlights the different derivatives of Benzimidazole.

Received on 30.03.2015 Accepted on 22.04.2015

Asian J. Pharm. Tech. 2015; Vol. 5: Issue 3, July- Sept. Pg 138-152

DOI: 10.5958/2231-5713.2015.00021.5

Panneer Selvam et al., synthesized a novel series of 2-substituted benzimidazole derivatives and were characterized by means of IR, 1H-NMR, 13C- NMR, mass spectral and elemental analysis. The compounds were screened for antibacterial and antifungal activities. The Minimum Inhibitory Concentrations was determined by agar streak dilution method. 1-(4-(1H-benzo[d]imidazol-2-yl)phenyl)-3-chloro-4-(4-nitro phenyl)azetidin-2-one (3a) was found to exhibit the most potent in vitro antimicrobial activity against E.coli, K.pneumoniae, S.aureus, S.epidermidis, C.albicans and A.niger respectively. All the other compounds exhibited moderate activity against the bacterial and fungal organism tested ^[3].

Reyila Wubulikasimu et al., synthesized a series of novel benzimidazole derivatives bearing a heterocyclic ring as oxadiazole, thiadiazole, triazole and evaluated for their activities against Coxsackie virus B3 and B6 in Vero cells. Compound 24 (IC50 = 1.08 μg/mL, SI = 61.7 against CVB3) was the promising candidate as lead compound for anti-enteroviral drug. It was observed in the incorporation of heterocyclic rings in benzimidazole at the 5-position could enhance their biological activities ^[4].

Ramineni Srinivasulu et al., synthesized benzimidazole derivatives using zinc triflate as an efficient catalyst. One-pot synthesis of 2-substituted benzimidazole derivatives from o-phynelyenediamine and substituted aldehydes were developed under zinc triflate in ethanol solvent at reflux temperature ^[5].

Sreena K et al., synthesized novel Benzimidazole derivatives by condensation of o-Phenylenediamine with acids in presence of Polyphosphoric acid and solvents like water and dilute hydrochloric acid. The synthesized compounds were analyzed mainly by IR spectral reading, physical and chromatography readings and screened for their anthelminitic activity. Among the synthesized compounds 2-phenylbenzimidazole showed potential anthelminitic activity 0.931±0.231 and 1.317±0.149 minutes for paralysis and death respectively when compared with the standard piperazine citrate ^[6].

B Guruswamy and R Arul synthesized various benzimidazole derivatives under micro-wave irradiation from simple and substituted ortho phenylenediamines (OPDA) and isonicotinic acid using SiO2/H2SO4 as catalyst. The structures of the synthesized compounds have been established on the basis of spectral and analytical data ^[7].

Joshi synthesized novel benzimidazole derivatives and was screened for their antimicrobial activity. Compound 2a showed significant activity ^[8].

Olayinka O. Ajani et al., synthesized a series of five 2-substituted benzimidazole precursors (1a-e) were synthesized via [4+1] condensation and imino compound (1f) by simple condensation in the presence of Conc. HCl as catalyst. Synthetic modification of N-1 position was achieved in order to obtain new 5-chloro-2,4- dinitrophenyl bearing 1,2-disubstituted benzimidazole 2a-e and 2f, and 3-chlorobenzyl bearing 1,2-disubstituted benzimidazole 3a-e and 3f in good to excellent yields using a facile approach. The chemical structures of all synthesized compounds were confirmed using spectroscopic means such as UV-visible, IR, Mass spectra, 1H and 13C NMR as well as C, H, N elemental analytical data ^[9].

Parmender Singh Rathee et al., synthesized two series of novel benzimidazole derivatives. The first one comprise of 2-methyl, the second one comprise of 2-phenyl substitution on benzimidazole moiety. Seven novel benzimidazole derivatives were synthesized successfully in appreciable yields and characterized physicochemically. The structures of all the synthesized derivatives were confirmed by IR and 1HNMR. Furthermore, the synthesized compounds were screened for antimicrobial activity (antibacterial activity and antifungal activity) by tube dilution method. Some of the synthesized compounds showed appreciable antifungal activity ^[10].

Shobhit Srivastava et.al., reported synthesis of a series of novel 2-phenylhydrazinomethyl and 2-(2-hydroxyphenyl)-benzimidazole derivatives substituted at the N1-position of benzimidazole nucleus and screened for analgesic activity. The incorporation of a phenylhydrazinomethyl nucleus at 2-position of benzimidazole compound gave a biologically active pharmacophore ^[11].

K. Ravi Kumar et. al., synthesized a library of benzimidazole derivatives through the reaction of o-phenylenediamine and aldehydes in the presence of catalytic amount of silica supported sodium hydrogen sulphate (NaHSO4-SiO2) under refluxing in ethanol solvent ^[12].

Canan synthesized a series of arious substituted benzimidazole derivatives containing fluoro and morpholino substituents at the 5 and 6 positions and their structures were identified by spectroscopic techniques. The targeted compounds 15 are undergoing biological investigation ^[13].

Walia et.al., synthesized new N-(2-(1H-benzo[d]imidazol-2-yl)phenyl)-N-phenylbenzamide derivatives. The reaction was carried out between o-phenylenediamine with substituted anthranilic acids. The resultant compounds were than refluxed with benzoyl chloride in the presence of pyridine to yield the product.The compounds were synthesised in normal yield and their structures were confirmed by IR, H1-NMR spectral data. The antimicrobial activity was evaluated against bacteria and fungi were studied. Compounds 6,8 and 10 possess good activity ^[14].

Venkateswarlu et.al.,, synthesized one pot 2-substituted benzimidazole derivatives from o-phenylenediamine and a variety of aldehydes were developed under mild reaction conditions using lanthanum chloride as an efficient catalyst ^[15].

Ashish Kumar and Anil Mishra synthesized two series of N- substituted benzimidazole derivatives, viz. 1-benzyl-2-substitued benzimidazole and 1-(p-chlorophenyl)-2- substituted benzimidazole derivatives. These compounds have been screened for Tobacco mosaic viruses and Sunhemp rosette viruses and compound 7 showed significant activity ^[16].

Mukesh et. al., synthesized some new benzimidazoles derivatives 4'-{5-amino-2-[2-substituted-phenylamino)-phenyl-methyl]-benzimidazol-1 ylmethyl}-biphenyl-2-carboxylic acid.

The compounds synthesized were identified by 1H NMR, 13C NMR, FAB Mass and FT-IR spectroscopic techniques. All compounds studied in this work were screened for their antihypertensive activity by tail cuff method and direct method measurement of blood pressure ^[17].

Vaidehi et.al., synthesized Some 2- substituted benzimidazole derivatives by condensation of o-phenylenediamine with carboxylic acid in presence of ring closing agents (polyphosphoric acid/Hcl). The Chemical structures of synthesized compounds were identified by spectral analysis. The synthesized compounds were screened for their in-vitro antibacterial activity against Standard strains by cup plate method ^[18].

Komal Petkar et.al., synthesized novel 2-chloromethyl-1H-benzimidazole derivatives for antifungal activity. These derivatives were prepared by condensing 2-chloromethyl-1H-benzimidazole with different aromatic amines and heterocyclic. The synthesized compounds were screened for their antifungal activity against Candida albicans by well plate method. Compound 8 was found to be active ^[19].

Radhika et.al., reported Docking studies of twenty novel 5-nitro benzimidazoles was done with the help of V Life MDS3.5 software using GRIP batch docking method by taking AT-2 receptor model with bovine rhodopsin crystal structure as a target. Based on the docking scores of the designed molecules which ranged from -14.39 to -36.16, the 5-nitro benzimidazole derivatives were synthesized by refluxing 4-nitro-1, 2-phenylenedimaine in dimethoxyethane with various substituted aromatic aldehydes in the presence of sodium metabisulphite as oxiding agent. The test compounds were characterized by TLC, melting point, UV, IR, 1H NMR and mass spectroscopy. All the compounds were evaluated for ex-vivo vasorelaxant activity in rat aorta rings pre-contracted with phenylepherine. Compounds BDZ3, BDZ6, BDZ12, BDZ18 and BDZ20 showed good vasorelaxant activity (EC50<30 μM) ^[20].

Vishvanath et. al., synthesized Benzimidazoles derivatives using a catalytic amount of Zinc acetate at room temperature. The advantages include low cost, ease of catalyst handling, mild reaction conditions and reactions carried out at room temperature with excellent yields ^[21].

Anshul Chawla et.al., reported a review on Benzimidazoles belonging to the fused heterocyclic system prepared from amino acids by microwave induced reactions which are associated with diverse pharmacological activities such as antimicrobial, antiviral, antidiabetic and anticancer activity ^[22].

Mohanraj et.al., reported anhydrous ZnCl₂ as a catalyst for the synthesis of 2-arylsubstituted benzimidazoles efficiently. All the synthesized compounds were characterized by melting point, IR, 1H NMR, 13C NMR spectral data ^[23].

Hamdan synthesized a set of six novel benzimidazole compounds. The chemical structures of these compounds were elucidated using NMR and elemental analysis. The biological activity of these compounds as fungicides was tested against three commercially known fungicides (C. albicans, patient isolate C. glabrata and C. krusei) ^[24].

Shet and Shelar synthesized a new series of 2-substituted alkyl thioarylbenzimidazole derivatives by condensing o-phenylenediamine with aryl and naphthyl thioglycolic acid. All these compounds were characterized by melting point, HPLC, IR and 1H NMR spectroscopic data. The synthesized compounds were screened for in vitro antibacterial activity against a variety of bacterial strains. Compound L 2-[(1-naphthylthio) methyl]-1H-benzimidazole showed remarkable antifungal activity^[25].

Chavan et. al., reported the synthesis of the novel Benzimidazole derivative with Aspirin and evaluated for antimicrobial and antifungal activities. The MIC of Benzimidazole derivative was found to be in the range 20-200 mg/ml on all the tested microorganisms ^[26].

Misbah ur Rehman et.al., reported a review on Mannich Base derivatives of benzimidazoles along with their anti-microbial properties ^[27].

Ansari et.al., reported synthesis of a number of N’-(arylmethylidene)-2-(2-methyl-1H-benzimidazol-1-yl)acetohydrazide and 4-aryl-5-[(2-methyl-1H-benzimidazol-1-yl)methyl]-4H-1,2,4-triazole-3-thiol derivatives were synthesized by incorporating various aromatic and heterocyclic substituents on 2-methyl-1H-benzimidazole. The structures of all the synthesized compounds were elucidated based on their elemental analysis and spectral data. The in vitro activities of these compounds against bacteria and fungi were evaluated by the disc diffusion method ^[28].

Sammaiah et.al., reported one-pot synthesis of benzimidazoles using ortho-phenylenediamine and aldehydes by condensation reaction in the presence of a mild Lewis acid cadmium chloride. All the reactions were carried out in acetonitrile at 80⁰ C to 85⁰ C ^[29].

Zygmunt Kazimierczuk et.al., reported synthesis of two series of benzimidazole derivatives. The first one was based on 5,6-dinitrobenzimidazole, the second one comprises 2-thioalkyl- and thioaryl-substituted modified benzimidazoles. Antibacterial and antiprotozoal activity of the newly obtained compounds was studied. Compound 5,6-dichloro-2-(4-nitrobenzylthio)-benzimidazole showed the most distinct antiprotozoal activity ^[30].

Mohamed Al Messmary et.al., reported synthesis of 2-substituted benzimidazoles by reaction of substituted benzoic acid with o-phenylenediamine, and then the products obtained were treated with secondary amines in the presence of formaldehyde in order to synthesize Mannich bases. The final products were characterized by physical and spectral analysis ^[31].

Vijey Aanandhi et.al., reported synthesis of a series of mannich bases of benzimidazole derivatives from o-phenylenediaamine in two steps via benzimidazole intermediates. The synthesized Compounds were characterized by IR, 1H NMR, mass and elemental analysis and were evaluated for their anti fungal activity against a panel of two pathogenic fungal strains namely, Aspergillus niger, and Candida albicans by two fold serial dilution method, antibacterial activity against B.subtilis, S .aureus, E. Coli, S. Typhi. Compounds 3a, 3b and 3c shows excellent antibacterial activity and compound 3a showed good antifungal activity ^[32].

Anil Reddy reported synthesis of 1, 2-Disubstituted Benzimidazole Derivatives using Mannich Bases. The compounds were confirmed by the analytical and spectral data and were evaluated for anti inflammatory activity by carrageenan induced paw edema ^[33].

Kumar Pradeep et.al., reported acute, subacute toxicity of selected Mannich bases of benzimidazole derivatives, using graphical model in albino mice. The dead animals were obtained from primary screening studies, LD50 value determination experiments and acute studies subjected to postmortem studies. The chronic administration of [1-(N-substituted amino) methyl]-2-ethyl benzimidazole derivatives for 14 days, the vital organs such as heart, liver, kidney, testis, spleen and brain were carefully evaluated by histopathological studies and any apparent and significant changes or differences from the norm were studied. From the acute administration of benzimidazole derivatives, the LD50 values were determined using graphical method. After calculation of LD50 values using graphical methods, we found a broad therapeutic Window and a high therapeutic index value for benzimidazole derivatives. Orally administration of the benzimidazole derivatives at doses of 100 - 1000 mg/kg body wt for 14 consecutive days to albino mice did not induce any short-term toxicity. Collectively, these data demonstrate that the Mannich bases of benzimidazole derivatives have a high margin of drug safety ^[34].

Misbah ur Rehman et.al., reported synthesis of novel Mannich base derivatives of Benzimidazole through the condensation reaction of benzimidazole derivative with formaldehyde and primary and/ secondary amine. Zinc (II), copper (II), nickel (II) and cobalt (II) complexes of Mannich bases have also been synthesized. All the compounds were characterized by elemental analysis, magnetic moment determination, molar conductivity measurement, thermogravimetric analysis, spectral and analytical data. All the compounds were screened for in-vitro antibacterial and antifungal activity against various bacterial and fungal strains. Almost all the compounds showed good potent activity against microorganisms ^[35].

Gangula Mohan Rao et.al., reported synthesis of series of new [1-(N,N-disubstituted)aminomethyl-2-(2,4-dinitrophenyl)sulphanyl]-6-substituted-1H-benzimidazoles by the Mannich reaction on 2-[(2,4-dinitrophenyl)sulphanyl]-5(6)-substituted-1H-benzimidazoles with appropriate secondary amine and paraformaldehyde in presence of concentrated hydrochloric acid in ethanol. The synthesized compounds have been evaluated for analgesic and anti-inflammatory activities. Compound 18e was found to be more potent ^[36].

Rita Bamnela and Shrivastava reported a series of N-Mannich bases of benzimidazolyl substituted 1H-isoindole-1,3(2H) dione derivatives. The chemical structures of synthesized N-Mannich bases were determined by elemental analysis and spectral data (FTIR and 1H NMR). All the synthesized derivatives have been evaluated for their antimicrobial, anthelmintic and insecticidal activities ^[37].

Shingare et.al., reported synthesis of mannich bases of benzimidazole derivatives as antiviral agents ^[38].

t Rakesh Kumar et.al., reported synthesis of benzimidazole derivatives and were screened for their anti-hypertensive activity. It is found that at position 5 of benzimidazole NH₂ group gives good activity ^[39].

Sharma et.al., reported synthesis of a series of 4'-(6-Methoxy-2-substituted-benzimidazole-1-ylmethyl)-biphenyl-2-carboxylic acid expeditiously in good yields from 4-methoxy-1, 2-phenylenediamine and different substituted carboxylic acids in the presence of BF3·OEt2 as a catalyst with biphenyl carboxylic acid and the synthesized compounds were confirmed by IR,1H NMR,MS and elemental analysis. The compounds have been evaluated for antihypertensive activity by direct and indirect methods ^[40].

Anupama Parate et.al., reported synthesis of a set of substituted 1, 2, 4 triazolinone derivatives. Systematic variation of the substituents at the ortho position of N- aryl triazolinones resulted in six novel compounds. The compounds have been evaluated in vivo antihypertensive activity via acute renal hypertension model. Compounds TZN1 and TZN4 emerged as maximally active compounds ^[41].

Singh Gurvindhar et.al., reported a review on chemistry of different benzimidazole derivatives along with their biological activities such as antimicrobial, analgesic, anticonvulsant, antihelmintic, antiprotozoal, antiviral, anticancer, antineoplastic ^[42].

Hiroyuki Nakano et.al., reported synthesis of of novel benzimidazole derivatives that suppress histamine release from mast cells, inhibit 5-lipoxygenase, and possess antioxidative action. Compound 22 potently suppressed histamine release from rat peritoneal mast cells triggered by the antigen-antibody reaction, inhibited 5- lipoxygenase in rat basophilic leukemia-1 (RBL-1) cells, and prevented the NADPH-dependent lipid peroxidation induced by Fe31–ADP in rat liver microsomes, in addition to an antagonizing the contraction of guinea pig ileum caused by histamine ^[43].

Kaushik et.al., reported synthesis of a series of N-substituted 4-methyl-6-(1-mehyl-1H-benzo[d]imidazol-2-yl)-2-propyl-1H-benzo[d]imidazole derivatives and have been reported to exhibit anticancer properties via DNA binding and interstrand cross-links in variety of cancer cell lines ^[44].

Bahram Dowlati et.al., reported Electrochemical Synthesis of Benzimidazole Derivative Using Carbon Electrode in Aqueous Medium. 1,3-diamino-5,6-dihydroxy-1H-benzo[d]imidazole-2(3H)-one is synthesized by the electrochemical oxidation of catechol in the presence of carbohydrazide ^[45].

Priyal Jain et.al., reported synthesis of 2-substituted-5-nitro benzimidazole derivatives and were screened for antimicrobial activity by disc diffusion method using Gram-positive (S. aureus,S. mutans and B. subtilis), Gram-negative (E. coli, S. typhi and P. aeruginosa) bacteria ^[46].

Sung Yun Cho et.al., reported synthesis of a series of benzimidazole derivatives containing oxycyclic pyridine and evaluated for their gastric H+/K+-ATPase inhibitory activity. Several of the synthesized compound exhibited potent anti secretion in pylorus-ligated rats when administered intradoudenally ^[47].

Gupta et.al., reported synthesis of a series of biologically active benzimidazole derivatives by the reaction of o-phenylenediamine with the derivatives of benzoic acid in presence of 4N-HCl followed by the reaction with piperazine and formaldehyde to undergo Mannich reaction. The structures of all the synthesized Mannich bases were characterized by UV, FTIR, 1H NMR, mass spectroscopy and elemental analysis. The compounds were evaluated for their anthelmintic activity by the identification of paralyzing and death time. The compounds 2e, 2h, 2k, 2l and 2m were found to possess significant antibacterial activity ^[48].

man Malik et.al., reported synthesis of hetero chelates of the type ML2.2H2O and ML2 of Lansoprazole drug 2 [[[ methyl – 4 (2,2,2 trifluroethoxy) 2 – pyridinyl] methyl] sulfonyl] – 1H – benzimidazole] with metal salts nickel(II) chloride ,cobalt(II) chloride and Mercury(II) chloride in 1:2 ratio . The metal complexes have been screened for their antibacterial and antifungal activities against bacteria Pseudomonas, Staphylococcus aureus and fungi Aspergillus Niger and A.flavous ^[49].

Kalyankar et.al., reported review on benzimidazole derivatives with their pharmacological activities ^[1].

Bhanupriya Bhrigu et.al., reported synthesis of a series of new 2-[(1-substituted phenylethylidine) hydrazine]-N-phenyl-1H-benzo[d]imidazole-1- carbothioamides to have the pharmacophoric elements essential for anticonvulsant activity. All the newly synthesized compounds were screened by two most adopted models, maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ). Interestingly, compounds 4e, 4f, 4g, 4h and 4j exhibited potent anticonvulsant results and in the neurotoxicity screening, most of the compounds were devoid of toxicity at the dose of 60 and 100 mg/kg ^[50].

Yoon et.al., reported synthesis of a series of novel polar benzimidazoles in a 4-step reaction starting from basic compound 4-fluoro-3-nitrobenzoic acid in good to excellent yield. The structure of the novel polar benzimidazoles were characterized and confirmed by elemental and mass spectral analysis as well as 1H and 13C NMR spectroscopic data. The compounds were screened for their acetylcholinesterase (AChE) inhibitory activities and the most potent compound was found to be 5e which gave IC50 value of 31.04 μM. All the compounds were found to be non-toxic when tested with VERO cells at 50 μM ^[51].

Prem Shankar et.al., reported synthesis of 2-phenyl benzimidazole derivatives and their schiff bases. The novel reaction of 3-(2-methylbenzimidazol-1-yl) propanoic acid hydrazide with CS2/KOH gave Oxadiazole derivative which underwent Mannich reaction to give 3-[(dialkylamino) methyl]-2phenyl-4(3H)-quinazolinone. All compounds were characterized by physical, chemical, analytical and spectral data. All compounds have been screened for their antimicrobial activity and anti-inflammatory activity ^[52].

Abbas Ahmadi and Babak reported synthesis of novel series of the derivatives of benzimidazole and the structures of all the synthesized compounds have been confirmed by IR, 1H- and 13C-NMR, Mass Spectroscopy and elemental analysis. The compounds have been evaluated for antifungal activities. Compound 5, 7, 8, 10 showed significant activity ^[53].

Mita D. Khunt et.al., reported synthesis of various benzimidazole and benzoxazole derivatives using green solvent PEG400. The main attractive features of this process are a mild reaction conditions, easy workup procedure and good to excellent yield. The structures of all the synthesized compounds were confirmed by 1H NMR, IR, MASS and Elemental Analysis ^[54].

Rekha et.al., reported synthesis of novel benzimidazole derivatives. The structure of the synthesized compounds were confirmed by FTIR, 1H NMR, 13C NMR and Mass spectral analysis The newly synthesized compound were subjected to antibacterial activity against Bacterial strains such as gram-positive (S. aureus and B. subtilis) and gram-negative (E.coli and Proteus vulgaris). Compound 6e was found to be more active ^[55].

Madhavi et.al., reported synthesis of N-Mannich base of substituted 2-phenyl Benzimidazole derivatives by using O-Phenylene diamine with different aromatic acids with corresponded to N-mannich base. Finally the synthesised compounds were characterized by TLC, MP and Spectral data. Synthesised compounds screened to antibacterial and antifungal activities by cup plate method and also evaluated for anti-inflammatory activity determined by carrageenan induced method. Compound H11 showed significant activity ^[56].

Ramesh Sawant and Deepali Kawade reported synthesis of a series of 2-phenyl benzimidazole-1-acetamide derivatives and their evaluation for antihelmintic activity using Indian adult earthworms, Pheretima posthuma. The structure of the compounds was elucidated by elemental analysis and spectral data. Compounds 3c, 3e, 3j, 3l and 3q were more potent ^[57].

Anil Reddy reported Synthesis, Characterization and Structural elucidation of some di-substituted 2-(α-hydroxy benzyl) Bezimidazole derivatives. The compounds were characterized by analytical methods like IR, NMR and MASS spectroscopy ^[58].

Vaidehi and Gnana Deepika reported synthesis of a set of 2-substituted benzimidazoles by condensation of ortho-phenylenediamine with substituted acids in presence of ring closing agents like Polyphosphoric acid/ HCl. The synthesized compounds were characterized by IR spectroscopy and Elemental analysis. All the synthesized compounds were screened for antihelmenthic activity ^[59].

Khan et.al., reported synthesis of a series of all new substituted 2-(pyrimidinylsulfinyl) benzamidazoles derivatives from different starting materials. The newly synthesized compounds were characterized by IR and elemental analysis and evaluation against antiulcer and antisecretory activity as a inhibition of gastric H+/K+ATPase by induction of gastric ulcerations experimentally in male Wister rats according to the method ^[60].

Periyasamy Selvam et.al., reported synthesis of a series of novel N-substituted benzimidazole derivatives by modifying the N-1 hydrogen of benzimidazole moiety with the substitution of sulphanilamide, sulphadimidine, sulphamethoxazole, 2-aminopyridine, pthalamide, benzamide, nicotinamide, anthranilic acid and 2- marcapto- benzimidazole by mannich reaction. The structure of the synthetic compounds was characterized by means of IR and PMR data. The anti-HIV activities of the new compounds were also screened for in vitro anti-viral activity against replication of HIV-1 (IIIB) and HIV-2 (ROD) in MT-4 cells using AZT- as standard and cytostatic activity were also studied by MT- 4/MTT assay. Benzimidazole derivative BSD inhibited the replication of HIV-1 and 2 (EC50= 35.40μg/ml and CC50>125μg/ml) in MT-4 cells ^[61].

Dhua and Biswas reported synthesis of some 2-aminomethyl benzimidazoles derivatives by reacting 2-chloromethyl benzimidazole with several amines and the compounds synthesized were identified by IR and NMR spectroscopy. Anti bacterial activity were screened against Staphylococcus aureus, Bacillus subtilis, and Salmonella typhi by zone inhibition method. Most of the compound shows potential anti bacterial activity ^[62].

Sreenivasulu et.al., reported review on benzimidazole as it is a versatile heterocycle possessing a wide spectrum of biological activities like antimicrobial, antiviral, antidiabetic, anticancer activity, numerous antioxidant, antiparasitic, antihelmintics, antiproliferative, antiHIV, anticonvulsant, anti-inflammatory, antihypertensive, antineoplastic, proton pump inhibitor and antitrichinellosis. Benzimidazoles possess significant biological activities like potential antitumor agents, smooth muscle cell proliferation inhibitors and in various areas of chemistry ^[2].

CONCLUSION:

The present studies reflect that benzimidazole is a nucleus that can be used potentially in drug discovery area and medicines as it has versatile biological activities. Therefore this substrate has a great scope for the discovery of new, better, safer and more potent chemotherapeutic agents.

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Received on 09.04.2015 Accepted on 18.05.2015

Asian J. Pharm. Tech. 2015; Vol. 5: Issue 3, July- Sept. Pg 129-137

DOI: 10.5958/2231-5713.2015.00020.3