(A) The v0(Asc)ox was measured for various MnPs which differ vastly with respect to their redox properties, lipophilicity/bioavailability, polarity, size and bulkiness. Initial rates were determined with 5 μM MnP, 5 mM EDTA and 0.15 mM sodium ascorbate under aerobic conditions at (25 ± 1)0C and at pH 7.8 maintained with either 0.05 M potassium phosphate or Tris buffer. (B) Relationship between v0(Asc)ox and E1/2 is of bell-shape. (C) Six cationic MnPs with the E1/2 ranging from −65 to +340 mV vs NHE are plotted: (#1) MnTE-2-PyPhP5+, (#2) MnTE-3-PyP5+, (#3) MnTE-2-PyP5+, (#4) MnTPhE-2-PyP5+, (#5), MnTnHexOE-2-PyP5+, and (#6) MnTnOct-2-PyP5+.