Metformin and Its Sulfenamide Prodrugs Inhibit Human Cholinesterase Activity

Table 2

Kinetic parameters of enzymatic reactions.

Compound		AChE			BuChE
		Km [μmol/mL]	Vmax [A/min]	I	Km [μmol/mL]	Vmax [A/min]	I
Metformin	A	0.056 ± 0.012	0.224 ± 0.002	M	NS	NS	—
	B	0.167 ± 0.024	0.164 ± 0.004		NS	NS
Phenformin	A	0.056 ± 0.028	0.230 ± 0.017	M	0.037 ± 0.015	0.159 ± 0.045	C
	B	0.083 ± 0.047	0.127 ± 0.003		0.152 ± 0.029	0.167 ± 0.039
Prodrug 1	A	0.091 ± 0.004	0.292 ± 0.008	NC	0.044 ± 0.025	0.222 ± 0.047	M
	B	0.097 ± 0.018	0.132 ± 0.003		0.087 ± 0.047	0.194 ± 0.008
Prodrug 2	A	NS	NS	—	0.046 ± 0.020	0.202 ± 0.019	M
	B	NS	NS		0.078 ± 0.024	0.091 ± 0.015
Prodrug 3	A	0.089 ± 0.003	0.290 ± 0.002	NC	0.045 ± 0.021	0.202 ± 0.019	NC
	B	0.078 ± 0.012	0.159 ± 0.026		0.054 ± 0.021	0.117 ± 0.022

The values are given as mean ± standard deviation (SD) in 3 independent experiments. NS—the kinetic parameters were not estimated. A—kinetic parameters for pure enzyme (K_m, V_max); B—kinetic parameters of tested compounds (inhibitors) (IC₅₀ concentrations) (K_m(i), V_max(i)). I—type of inhibition, M—mixed type, NC—inhibition noncompetitive, C—inhibition competitive.