Fig. 4

a The concentration–response curve of bacterioruberin obtained GraphPad Prism 9 (San Diego, CA) statistical program with the built-in equation for nonlinear regression, i.e. Asymmetric (five-parameter, 5P) statistical model. The nearest recorded responses (A and B) of each experimental concentration (D and C), nearly equidistant on either side of the EC₅₀ and forming a right-angled triangle as in method of Alexander et al. (1999); b graphic magnification of right-angled triangle of data from experiment No. 1 (Table 1) for calculation of the EC₅₀ of bacterioruberin using the right-angled triangle method; c time to reach steady state TEC₅₀ with the EC₅₀ concentration of bacterioruberin. Data are expressed as mean ± SD of five independent experiments