Journal: Scientific Reports

Article Title: pK a of opioid ligands as a discriminating factor for side effects

doi: 10.1038/s41598-019-55886-1

Figure Lengend Snippet: Chemical structures of fentanyl, N-{1-[2-(2,6-difluorphenyl)ethyl]piperidine-4-yl}-N-phenylpropionamide (FF6), (±)- N -[1-(2-fluoro-2-phenylethyl)piperidine-4-yl]- N -phenyl propionamide (FF3) and (±)- N -(3-fluoro-1-phenethylpiperidine-4-yl)- N -phenyl propionamide (NFEPP). The blue circle highlights the tertiary nitrogen atom subjected to pH-dependent protonation in whose vicinity electrons may be withdrawn to reduce the pK a value. The respective isomers of FF3 and NFEPP are shown. Sites of fluorination are indicated as F.

Article Snippet: FF6 (base) was synthesized by a contractor (ASCA GmbH, Berlin, Germany) (Fig. ).

Techniques:

Journal: Scientific Reports

Article Title: pK a of opioid ligands as a discriminating factor for side effects

doi: 10.1038/s41598-019-55886-1

Figure Lengend Snippet: Binding and activation of MOR. ( A ) Displacement of bound [³H]-DAMGO (4 nM) by FF6 at pH 6.5 and 7.4. ( B ) IC 50 calculated from ( A ). P > 0.05, unpaired t -test (n = 6–7). ( C ) [ 35 S]-GTPγS binding induced by FF6 at pH 6.5 and 7.4. [ 35 S]-GTPγS binding is expressed as percent increase in [ 35 S]-GTPγS binding relative to binding in unstimulated samples (n = 6). ( D ) EC 50 of FF6 from ( C ). P > 0.05, unpaired t -test. Data are presen t ed as mean ± SEM (A, C) and as mean ± 95% confidence intervals (B, D) (n = 6).

Article Snippet: FF6 (base) was synthesized by a contractor (ASCA GmbH, Berlin, Germany) (Fig. ).

Techniques: Binding Assay, Activation Assay

Journal: Scientific Reports

Article Title: pK a of opioid ligands as a discriminating factor for side effects

doi: 10.1038/s41598-019-55886-1

Figure Lengend Snippet: Comparison of in vitro effects of compounds with different pK a values.

Article Snippet: FF6 (base) was synthesized by a contractor (ASCA GmbH, Berlin, Germany) (Fig. ).

Techniques: Comparison, In Vitro, Binding Assay

Journal: Scientific Reports

Article Title: pK a of opioid ligands as a discriminating factor for side effects

doi: 10.1038/s41598-019-55886-1

Figure Lengend Snippet: Antinociceptive effect of systemic FF6 in the unilateral CFA-induced hindpaw inflammation. ( A – D ) Elevation of PPT after intravenous (i.v.) injection of fentanyl (Fen) ( A , B ) and FF6 ( C , D ) in inflamed ( A , C ) and noninflamed ( B , D ) hindpaws, assessed before (Basal) and 4 days after i.pl. CFA application (0) at 10 to 60 min after injection of fentanyl or FF6. § P < 0.01, + P < 0.001 vs . corresponding baseline threshold (Basal) before CFA injections, paired t -test or Wilcoxon tes t ; # P < 0.05, * P < 0.001 vs. vehicle, two-way RM ANOVA and Bonferroni test (n = 8–10). ( E – L ) Effects of antagonists on PPT elevations produced 10 min after i.v. injection of fentanyl ( E – H ) or FF6 ( I – L ) (each at 16 µg/kg). Naloxone hydrochloride (NLX, 2 mg/kg) or vehicle (Veh) were injected subcutaneously (s.c.) ( E,G,I,K ). Naloxone methiodide (NLXM, 50 µg) or vehicle (Veh) were injected intraplantarly (i.pl.) into both hindpaws ( F , H , J , L ). * P < 0.05, ** P < 0.01, *** P < 0.001 NLXM or NLX + Fen or FF6 vs. Veh + Fen or FF6, unpaired t- test; ++ P < 0.01, +++ P < 0.0001 vs. corresponding baseline thresholds (dashed lines) evaluated 4 days after CFA, but before any injections; paired t -test or Wilcoxon test (n = 10 animals per condition for all except vehicle in J and L (n = 8)). Da t a are presented as mean ± SEM.

Article Snippet: FF6 (base) was synthesized by a contractor (ASCA GmbH, Berlin, Germany) (Fig. ).

Techniques: Injection, Produced

Journal: Scientific Reports

Article Title: pK a of opioid ligands as a discriminating factor for side effects

doi: 10.1038/s41598-019-55886-1

Figure Lengend Snippet: Central and intestinal side effects induced by systemic fentanyl and FF6. ( A ) Effects of subcutaneous (s.c.) fentanyl and FF6 (each at 30 µg/kg) on locomotion, expressed as the total distance (in cm) travelled during 30 min after drug injection. * P < 0.05, ** P < 0.01 vs . vehicle, one-way ANOVA and Dunnett’s test. ( B ) Effects of fentanyl and FF6 on constipation presented as the number of defecations during 1 h after s.c. fentanyl or FF6 injection. ** P < 0.01, *** P < 0.001 vs. vehicle, Kruskal-Wallis ANOVA and Dunn’s test. Data are presented as mean ± SEM (n = 10 animals per condition).

Article Snippet: FF6 (base) was synthesized by a contractor (ASCA GmbH, Berlin, Germany) (Fig. ).

Techniques: Injection

Journal: Scientific Reports

Article Title: pK a of opioid ligands as a discriminating factor for side effects

doi: 10.1038/s41598-019-55886-1

Figure Lengend Snippet: Correlation between pK a values of compounds with antinociception and side effects. ( A,B ) Antinociceptive effects as net AUC (4–12 μg/kg) of PPT (negative values result from subtraction of pre-CFA baseline PPT) at 15 min after i.v. injection of NFEPP, FF3, FF6 and Fen in inflamed ( A ) and contralateral, noninflamed ( B ) paws. AUC values were derived from curves generated by use of n = 9 (NFEPP and FF3 from , ), n = 8–10 (FF6, see also Fig. ) and n = 19 (Fen) animals. ( C ) Constipation, as assessed by number of fecal boli 1 h after s.c. injection of agonists (30 μg/kg) in relation to the pK a of the substance. Maximum and minimum numbers (with 95% confidence intervals) of boli in controls (vehicle-treated) are shown by the dashed line. Fen (n = 30) and controls (n = 34) (always included in all experiments) are averaged across all experiments; NFEPP (n = 11); FF3 (n = 12); FF6 (n = 10). ( D ) Locomotor activity as assessed by the total distance travelled during 30 min after s.c. injection of agonists (30 μg/kg) in relation to the pK a of the substance. Maximum and minimum travelled distances (with 95% CI) in controls (vehicle-treated) are shown by the dashed line. Fen (n = 31) and controls (n = 34) (always included in all experiments) are averaged across all experiments; NFEPP (n = 10); FF3 (n = 12); FF6 (n = 10). Graphs show means ± SEM (where available).

Article Snippet: FF6 (base) was synthesized by a contractor (ASCA GmbH, Berlin, Germany) (Fig. ).

Techniques: Injection, Derivative Assay, Generated, Activity Assay