Synthesis and Antimicrobial Activity of 1,2-Benzothiazine Derivatives

Patel, C, Bassin, J, Scott, M, Flye, J, Hunter, A, Martin, L ORCID: https://orcid.org/0000-0002-5330-5700 and Goyal, M, 2016. Synthesis and Antimicrobial Activity of 1,2-Benzothiazine Derivatives. Molecules, 21 (7), p. 861. ISSN 1420-3049

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Abstract

A number of 1,2-benzothiazines have been synthesized in a three-step process. Nine chalcones 1–9 bearing methyl, fluoro, chloro and bromo substituents were chlorosulfonated with chlorosulfonic acid to generate the chalcone sulfonyl chlorides 10–18. These were converted to the dibromo compounds 19–27 through reaction with bromine in glacial acetic acid. Compounds 19–27 were reacted with ammonia, methylamine, ethylamine, aniline and benzylamine to generate a library of 45 1,2-benzothiazines 28–72. Compounds 28–72 were evaluated for their antimicrobial activity using broth microdilution techniques against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Proteus vulgaris and Salmonella typhimurium). The results demonstrated that none of the compounds showed any activity against Gram-negative bacteria P. vulgaris and S. typhimurium; however, compounds 31, 33, 38, 43, 45, 50, 53, 55, 58, 60, 63 and 68 showed activity against Gram-positive bacteria Bacillus subtilis and Staphylococcous aureus. The range of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was 25–600 µg/mL, though some of the MIC and MBC concentrations were high, indicating weak activity. Structure activity relationship studies revealed that the compounds with a hydrogen atom or an ethyl group on the nitrogen of the thiazine ring exerted antibacterial activity against Gram-positive bacteria. The results also showed that the compounds where the benzene ring of the benzoyl moiety contained a methyl group or a chlorine or bromine atom in the para position showed higher antimicrobial activity. Similar influences were identified where either a bromine or chlorine atom was in the meta position.

Item Type:	Journal article
Publication Title:	Molecules
Creators:	Patel, C., Bassin, J., Scott, M., Flye, J., Hunter, A., Martin, L. and Goyal, M.
Publisher:	MDPI
Date:	30 June 2016
Volume:	21
Number:	7
ISSN:	1420-3049
Identifiers:	Number Type 10.3390/molecules21070861 DOI
Divisions:	Schools > School of Science and Technology
Record created by:	Jonathan Gallacher
Date Added:	05 Jul 2016 11:06
Last Modified:	09 Jun 2017 14:03
URI:	https://irep.ntu.ac.uk/id/eprint/28073

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