Journal of Pharmacy Research Vol.2.Issue 11.November 2009 Jitender K Malik et al. / Journal of Pharmacy Research 2009, 2(11),1687-1690 1687-1690 Review Article ISSN: 0974-6943 Available online through http://jprsolutions.info Jitender K Malik 1 *, Dr.F.V. Manvi 2 , Dr B.K. Nanjwade 2 , Punkaj Purohit 1 1 R.D.Memorial College Of Pharmacy, Bhopal. (M.P.). 2 K.L.E.S’ s College of Pharmacy, Belgaum.(KA) Received on: 20-05-2009; Accepted on:15-07-2009 ABSTRACT In recent year heterocyclic compounds analogues and derivatives have attracted strong interest due to their useful biological and pharma- cological properties. The small and simple benzothiazole nucleus is present in compounds involved in research aimed at evaluating new products that possess biological activities, such as anti-tumor, anti-microbial, anthelmintic, anti-leishmanial, anti-convulsant and anti-inflam- matory. The present review focuses on the benzothiazoles with potential activities that are now in development. Keywords: Benzothiazole, Heterocyclic compound and Biological activities. * Corresponding author. Tel.: + 91-9893864455 Telefax: +91- E-mail: jitender_malik@hotmail.com I NTRODUCTI ON Benzothiazoles are bicyclic ring system with multiple appli- cations. In the 1950s, a number of 2-amino benzothiazoles were inten- sively studied as central muscle relaxants. Biologist’s attention was drawn to this series when the pharmacological profile [1] was discov- ered. 6-trifluoromethoxy-2-benzothiazolamine was found to interfere with glutamate neurotransmission in biochemical, electrophysiologi- cal and behavioral experiments. After that benzothiazole derivatives have been studied extensively and found to have diverse chemical reactivity and broad spectrum of biological activity. Although they have been known from long ago to be bio- logically active [2] their varied biological features are still of great scientific interest. Benzothiazoles show antitumor activity, especially the phenyl-substituted benzothiazoles [3] , while condensed pyrimido benzothiazoles and benzothiazolo quinazolines exert antiviral activ- ity [4] . Recently, have described the synthesis of bis-substituted amidino benzothiazoles as potential anti HIV agents [5] . Substituted 6-nitro-and 6-amino benzothiazoles [6] show antimicrobial activity. Given below is a brief account of various alterations conducted on benzothiazole ring and their associated biological activities. Antitumor activity: A series of potent and selective antitumor agents mostly from substituted 2-(4-aminophenyl) benzothiazoles were developed and examined, in vitro, their antitumor activity in ovarian, breast, lung, renal and colon carnicoma human cell lines [7] . Pyrimido benzothiazole and benzothiazolo quinoline derivatives [8] , imidazo benzothiazoles [9] as well as, polymerized benzothiazoles [10] showed New 2-Amino Substituted Benzothiazoles: A new profile of biological activities antitumor activity. 2-(4-Aminophenyl) benzothiazoles [11] , comprise a novel mechanistic class of antitumor agents. Their unusual activity was first recognized from the distinctive biphasic-dose response relation- ship shown in in vitro assays against sensitive breast tumor cell lines, e.g., MCF-7 and MDA-468. Potency against these breast lines and others was independent of the estrogen or growth factor recep- tor status of the cells. Introduction of methyl or halogen substituent into the 3'-position of the 2-phenyl group enhances potency and extends the spectrum of action to certain colon, lung, melanoma, renal and ovarian cell lines. Fluorinated analogues of 2-(4-aminophenyl) benzothiazoles have been synthesized which successfully block C-oxidation. 2-(4- Amino-3-methylphenyl)-5-fluorobenzothiazoles is the favored ana- logue for clinical consideration possessing enhanced efficacy in vitro and superior potencies against human breast and ovarian tumor xe- nografts implanted in nude mice. Quinol esters and ethers [12] derived from the oxidation of 2- (4-hydroxyphenyl) benzothiazoles and quinine monoketals from the oxidation of 2-(3-hydroxyphenyl benzothiazoles, respectively, have significantly improved and extended antitumor potency in vitro against pairs of breast and colon human tumor cell lines. In in vitro growth inhibition tests against the human breast cancer cell lines MCF-7 and MDA-468 determined by MTT assay, the phenolic benzothiazole gave IC 50 values (dose to inhibit cell growth by 50%) of 0.62 and 0.06 μM, respectively. The 2-cyano derivatives exhibit interesting in vitro antitumor activity. As for the 4, 7- dimethoxybenzothiazoles, removal of the cyano substituent present in the 2-position of the dioxino-benzothiazole ring involved the lost of activity (IC 50 >100 μM).