Isothermal microcalorimetric investigation of the toxic action of the effective constituents of Podophyllum emodi Wall on Tetrahymena thermophila BF5

• Published in: Journal of thermal analysis and calorimetry 2014-03, Vol.115 (3), p.2369-2374
• Main Authors: Gong, M., Zhang, N., Sun, Y.-Q., Luo, S.-Q., Zhao, Y.-L., Wang, X. Z., Yan, D., Xiao, X.-H., Li, J.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Calorimetry; Chemistry; Chemistry and Materials Science; Inhibitors; Inorganic Chemistry; Measurement Science and Instrumentation; Metabolism; Physical Chemistry; Polymer Sciences; Rate constants; Toxic; Toxicity; Toxicology; Walls
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-013-3314-x

The effects of podophyllotoxin (PPT), etoposide (VP16), and teniposide (VM26) on the growth of Tetrahymena thermophila BF 5 ( T.t. BF 5 ) was investigated by the TAM AIR isothermal microcalorimetric system. The extent and duration of toxic effects on T.t. BF 5 metabolism were evaluated by studying the growth rate constant ( k ), inhibitory ratio ( I ), maximum heat-output power ( P max ), peak time of maximum heat-output power ( t p ), and total heat production ( Q t ). Experimental results showed that the value of t p increased and the value of k and P max decreased with the increasing compound concentrations. Furthermore, the growth rate constant k was linear with compound concentration. The corresponding I was obtained from different k values. According to the IC 10 (the concentration of inhibitor when the inhibitory ratio is 10 %), the relative toxicity of the three compounds was PPT (IC 10  = 49.6 μg mL −1 ) > VP16 (IC 10  = 117.5 μg mL −1 ) > VM26 (IC 10  = 359.1 μg mL −1 ). The preliminary investigation of structure–activity relationships showed that the thienyl group was likely responsible for reducing the toxicity of the compounds.