Metabolism of 2EN (A and B), 2NPE (C and D), 3EPh (E and F), 2PPh (G and H), 3PPh (I and J), and 4BPE (K and L) by P450 2A13 in the absence (A, C, E, G, I, and K) and presence (B, D, F, H, J, and L) of an NADPH-generating system, using analysis with HPLC. Possible formation of metabolite(s) from these chemicals was denoted as “*” in the figures.