3.8.3. In Vitro Cytotoxicity Using the MTT Assay Method

The in vitro cytotoxic efficacy of cypermethrin before and after bacterial degradation was investigated against normal Vero cell line (normal kidney cell from African green monkey) using MTT [3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] viability assay method. The conducted treatments were negative control (cypermethrin at 2500 ppm without bacterial degradation) and biodegradable products (see seed germination section). The cells are obtained from ATCC (American type culture collection). Cells at concentration 1 × 10⁵ cell/mL are inoculated into a 96-well plate containing 0.2 mL media/well and incubated for 48 h at 37 °C after being treated with double-fold concentration (2500–9.7 µg mL⁻¹) of cypermethrin before and after degradation. At the end of the incubation period, approximately 30 µL of MTT (5mg/mL dissolved in phosphate buffer) was mixed with each well and incubate the plate at 37 °C, 5% CO₂ for 5 h. The purple color is formed after adding 1 mL of DMSO due to formazan crystal formation [85]. The experiment was performed in triplicate. The color intensity was measured at 560 nm using an ELISA plate reader and the cell viability was calculated according to the following equation [86].