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Synthesis and Toxicity Evaluation of Some N4-Aryl Substituted 5-Trifluoromethoxyisatin-3-thiosemicarbazones
Department of Chemistry, Bahauddin Zakariya University, Multan-60800, Pakistan
Department of Chemistry, FC College, Lahore-54600, Pakistan
H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan
* Author to whom correspondence should be addressed.
Received: 16 June 2011; in revised form: 13 July 2011 / Accepted: 22 July 2011 / Published: 29 July 2011
Abstract: A series of twenty one N4-aryl substituted 5-trifluoromethoxyisatin-3-thiosemicarbazones 3a-3u was synthesized by the reaction of trifluoromethoxyisatin 1 with different arylthiosemicarbazides 2 in aqueous ethanol (50%), containing a few drops of acetic acid. Their structures were established on the basis of analytical (CHN) and spectral (IR, 1H-NMR, EIMS) data. All the synthesized compounds were evaluated for their toxicity potential by a brine shrimp lethality bioassay. Ten compounds i.e., 3a, 3e, 3i-3l and 3n-3q proved to be active in this assay, displaying promising toxicity (LD50 = 1.11 × 10−5 M − 1.80 × 10−4 M). Amongst these, 3k, 3n and 3o were found to be the most active ones (LD50 = 1.11 × 10−5 M − 1.43 × 10−5 M). Compound 3k showed the highest activity with a LD50 value of 1.11 × 10−5 M and can, therefore, be used as a lead for further studies. Structure-activity relationship (SAR) studies revealed that the presence of strong inductively electron-attracting trifluoromethoxy substituent at position-5 of the isatin moiety played an important role in inducing or enhancing toxic potentiality of some of the synthesized compounds.
Keywords: isatin; 5-trifluoromethoxyisatin; thiosemicarbazones; 5-trifluoromethoxyisatin-3-thiosemicarbazones; toxicity
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Pervez, H.; Saira, N.; Iqbal, M.S.; Yaqub, M.; Khan, K.M. Synthesis and Toxicity Evaluation of Some N4-Aryl Substituted 5-Trifluoromethoxyisatin-3-thiosemicarbazones. Molecules 2011, 16, 6408-6421.
Pervez H, Saira N, Iqbal MS, Yaqub M, Khan KM. Synthesis and Toxicity Evaluation of Some N4-Aryl Substituted 5-Trifluoromethoxyisatin-3-thiosemicarbazones. Molecules. 2011; 16(8):6408-6421.
Pervez, Humayun; Saira, Naveeda; Iqbal, Mohammad Saeed; Yaqub, Muhammad; Khan, Khalid Mohammed. 2011. "Synthesis and Toxicity Evaluation of Some N4-Aryl Substituted 5-Trifluoromethoxyisatin-3-thiosemicarbazones." Molecules 16, no. 8: 6408-6421.