3.1.3. The MTT staining incubation timeReduction of MTT to formazan is associated to oxidation ofNADPH-dependent cellular oxidoreductase enzymes of living cells[37]. The incubated plates were immersed (1 s at a speed of3.5 cm/s) into the MTT solution and then incubated again for 30 minat 37◦C. Afterwards, the plate was dried on the TLC Plate Heater(already adjusted to 50◦C) for 10 min. The fast drying as well as theautomated immersion of the plates, instead of a spraying, enabled abetter visual contrast due to sharp inhibition zones, a homogenousbackground of the bioautogram and an even baseline for densito-metric measurement. It was evident that the fast drying after MTTincubation resulted in the rapid evaporation of the water, avoid-ing any further diffusion of the zones. Since formazan crystals areinsoluble in water, their color was more intense in the absence ofwater. Thus, via the fast drying, a post-treatment of the plate withethanol was skipped [20]. This reported extra step was applied toimprove the contrast due to the solubility of formazan in ethanol.