Evaluation of Cytotoxicity with Fish Cell Lines: A Case Study for α-Oligothiophenes (1-5 Rings)

Abstract

This study was designed to compare two continuous fish cell lines in culture, BB and RTG-2, for their ability to determine cytotoxicity based upon the phototoxicological action of a set of ?-oligothiophenes with 1-5 rings (αl,…,α5). Cells were incubated in optimal growing conditions for 1, 2, and 6 days after inoculated with thiophenes and irradiated 20 minutes with Phillips TL D lamps (15W, spectral distribution 300-500nm). Three end-points were measured as markers of phototoxicity (compared to “dark” experiments): i) mitochondrial activity (MTT reduction), ii) membrane integrity (LDH released activity), and iii) cell adherence. Inhibitory concentrations 50% (IC50) were obtained from concentration effect curves.

The concentrations of thiophenes causing IC50 in the MTT reduction, and the pattern of phototoxicity, α3>α4≅α5≅α2>α1, was identical for both cell lines). These results agree very well with the predicted phototoxicity taking into account both the partition coefficients in micro-heterogeneous systems that mimic the environment of the molecules in vivo, and the “killing factor”, the efficiency of singlet oxygen production. The maximum of the predicted as well as the experimental values occur at α3, the member of the family which occur in larger amount in the nature.