Table 5.

Conformational tuning at N3 and C2′ north: effect on lipophilic binding efficiency.

Compd	R1	R2	HNE IC50 [nm][a]	log D[b]/Clog D[c]	LipE[d]	CYP 2C9/3A4 IC50 [μm][e]
22	H	H	4.7	2.8[b]	5.6	18/>50
25	Me	H	1.6	3.6[c]	5.2	23/40
26	H	CF3	0.6	3.2[b]	6.0	>50/>50
27	Me	CF3	0.024	3.7[b]	7.0	–/>20
28	H	SO2Me	0.540	2.7[b]	7.2	>50/>50
BAY 85-8501 (29)	Me	SO2Me	0.065	3.0[b]	7.2	>50/>50
30	Me		0.250	3.3[c]	6.3	>50/>50

^[260] The inhibitory capacity of test compounds was assessed by applying functional biochemical assays with the isolated enzyme (Supporting Information); IC₅₀ values were derived from enzyme activity data (pH 7.4) in the presence/absence of various compound concentrations by applying a suitable fluorogenic peptide substrate, MeOSuc-AAPV-AMC.

^[b] log D (pH 7.5) was determined by reversed-phase HPLC at physiological pH 7.5. A series of standards were injected for which log D has already been determined using definitive analytical methods (a homologous series of n-alkanones). Plotting of the retention times against their log D generated a calibration curve. The retention time of the test compound was then compared with the calibration curve leading to its log D.

^[c] Clog D (pH 7.5) was calculated by using a highly predictive method developed at Bayer, based on data points of experimentally determined log D values of internal pharmaceutical compounds and the Simulations Plus pK_a predictor.[23]

^[d] Calculated as LipE=pIC₅₀−log D.[24]

^[e] The potency of test compounds to inhibit human CYP 2C9 and CYP 3A4 was investigated with pooled human liver microsomes as enzyme source and selective standard substrates (Supporting Information); IC₅₀ values were derived from enzyme activity data (pH 7.4) in the presence/absence of various compound concentrations and diclofenac/midazolam as selective CYP 2C9/CYP 3A4 substrate.