Jianquan Zheng

Pharmacological profiles of an anticholinergic agent, phencynonate hydrochloride, and its optical isomers

AbstractAim:To comparatively study the pharmacological profiles of 3-methyl-3-azabicyclo (3,3,1)nonanyl-9-α-yl-α-cyclopentyl-α-phenyl-α-glycolate (phencynonate hydrochloride, CPG), an anticholinergic agent, and its enantiomers [R(–)- and S(+)-CPG].Methods:The affinity and relative efficacy were tested using radioligand-binding assay with muscarinic acetylcholine receptors from rat cerebral cortex. The pharmacological activities were assessed in three individual experiments: (1) potentiating the effect of subthreshold hypnotic dose of sodium pentobarbital; (2) inhibiting oxotremorine-induced salivation; and (3) inhibiting the contractile response to carbachol.Results:The order of potency of phencynonate hydrochloride and its optical isomers to inhibit the binding of [3H]quinucli-dinyl benzilate ([3H]QNB) was R(–)-CPG (Ki=46.49±1.27 nmol/L)>CPG (Ki=271.37± 72.30 nmol/L)>S(+)-CPG (Ki=1263.12±131.64 nmol/L). The results showed that R(–)-CPG had the highest affinity to central muscarinic receptors among the three compounds, but did not show any central depressant effects at dose from 10.00 to 29.15 mg/kg. CPG increased the effects of subthreshold hypnotic dose of sodium pentobarbital induced-sleeping [the ED50±95% LC value was 21.06±3.04 mg/kg]. CPG and R(–)-CPG displayed nearly equipotent effect in depressing oxotremorineinduced salivation [the ED50± 95% LC for R(–) and CPG were 1.10±0.28 and 1.07 ± 0.15 mg/kg, respectively], and the contractile response to carbachol (pA2 values for R(–) and CPG were 6.84 and 6.80, respectively). S(+)-CPG presented the lowest anticholinergic profiles, but could potentate effects of its enantiomers in some manner.Conclusions:These data suggested that R(–)-CPG acted as an eutomer in racemate and a competitive antagonist to acetylcholine muscarinic receptors, but S(+)-CPG was less active in comparison to R(–)-CPG and its racemate. The central depressant effects of R(–)-CPG and S(+)-CPG were lower in comparison to its racemate.

Novel selective antagonist of the cannabinoid CB1 receptor, MJ15, with prominent anti-obesity effect in rodent models.

MJ15, a novel cannabinoid CB(1) receptor selective antagonist was discovered. In receptor binding assays, MJ15 displayed a high affinity for rat cannabinoid CB(1) receptor (K(i)=27.2 pM, and IC(50)=118.9 pM), but a much lower affinity for rat cannabinoid CB(2) receptor (only 46% inhibition at 10 microM). At the cellular level, the IC(50) values against activation of cannabinoid CB(1) and CB(2) receptors induced by Win55212-2 in specially designed EGFP-CB(1)_U2OS and EGFP-CB(2)_U2OS cells were 0.11 microM and >10 microM, respectively. In addition, MJ15 dose-dependently blocked Win55212-2 mediated increase of intracellular Ca(2+) levels in hippocampal cells and reversed the inhibitory effects of cannabinoid CB(1) receptor agonist on forskolin-stimulated adenylyl cyclase activity in CHO cells expressing the human cannabinoid CB(1) receptor. In animal experiments, MJ15 demonstrated remarkable effects from 20 to 40 mg/kg, including promoted the small intestine peristalsis in ICR mice and inhibited food intake and body weight increase in diet-induced obesity (DIO) rat and mouse. 40 mg/kg MJ15 significantly reduced food intake at initial 2 weeks of treatment, prevented the increase of body weight and adipose by 46% and 28% respectively in DIO rats, and reduced body weight and adipose gain by 70% and 23% respectively in early onset obesity DIO mice after 4 weeks treatment. Meanwhile, dyslipidemia were ameliorated in both models. Taken together the in vitro and in vivo data, MJ15 is demonstrated to be a potent and selective cannabinoid CB(1) receptor antagonist and holds a prominent potency in obesity and dyslipidemia treatment.

Pharmacological characterization of 3-azabicyclo[3,2,1] octane-1-yl-l-leucyl-d-tryptophanyl-d-4-Cl-phenylalanine: A novel ETA receptor-selective antagonist

BACKGROUND AND OBJECTIVESnPulmonary hypertension is a kind of disease associated with a very high rate of mortality. There are not many effective drugs for the treatment of pulmonary hypertension. Treatment with ET-1 receptor antagonists was proved to be effective in the treatment of pulmonary hypertension. Aiming at developing new endothelin A receptor (ET(A)) antagonist for treatment of pulmonary hypertension, 242 peptide compounds were synthesized by structural optimization of a selective ET(A) receptor antagonist BQ-123. Among these, -azabicyclo[3,2,1]octane-1-yl-l-Leucyl-d-tryptophanyl-d-4-Cl-phenylalanine, named ETP-508, was selected for further harmacological characterization.nnnMETHODSnRadioligand binding assay was performed to study the binding affinity of ETP-508 for ET(A) and ET(B) receptors. The biological activity of ETP-508 was evaluated in isolated rat aortic ring experiment and in systemic arterial pressure experiment. In addition, hypotensive effect of ETP-508 was investigated on hypoxia-induced pulmonary hypertension.nnnRESULTSnETP-508 binds to endothelin ET(A) receptor with >10,000-fold higher affinity than to endothelin B receptor in rat lung tissue preparation. ETP-508 inhibited endothelin-1 (ET-1)-induced contraction of isolated rat aortic ring and shifted the cumulative concentration-contraction response curve to ET-1 to right with no change in the maximal response. In vivo, ETP-508 inhibited the increased effect of ET-1 on mean systemic arterial pressure. Pre-treatment with ETP-508 by intravenous infusion significantly inhibited chronic hypoxia-induced pulmonary hypertension and right ventricular hypertrophy. ETP-508 also significantly inhibited the increase in lung ET-1 expression level, hemoglobin, red-cell count and red-cell hematocrit as induced by hypoxia. Furthermore, ETP-508 partially reversed pre-established pulmonary hypertension and right ventricle hypertrophy by chronic hypoxia.nnnCONCLUSIONnThese results indicated that ETP-508 is a novel highly selective ET(A) receptor antagonist and may have a great potential to be developed as a drug of anti-pulmonary hypertension.

Comparative study on pharmacological effects of DM-phencynonate hydrochloride and its optical isomers

AbstractAim:The 3-azabicyclo(3,3,1)nonanyl-9-α-yl-α -cyclopentyl-α -phenyl-α -glycolate (DM-phencynonate hydrochloride, DMCPG) is a demethylated metabolite of 3- methyl-3-azabicyclo(3,3,1)nonanyl-9-α-yl-α-cyclopentyl-α-phenyl-α-glycolate (phencynonate hydrochloride, CPG). (±)DMCPG had one chiral center and two enantiomers [R(-) and S(+)DMCPG]. Here we carried out a comparative study of the pharmacological profiles of these optical isomers.Methods:Affinity and relative efficacy were tested using a radioligand-binding assay with muscarinic acetylcholine receptors from the rat cerebral cortex. Pharmacological activity was assessed in three individual experiments: (1) potentiating the effect of a subthreshold hypnotic dose of sodium pentobarbital; (2) inhibiting oxotremorine- induced salivation; and (3) inhibiting the contractile response to carbachol.Results:In the competitive binding assay, R(−)DMCPG (Ki=763.75 nmol/L) was 4- and 2-fold more potent than (±)DMCPG (Ki=3186 nmol/L) and S(+)DMCPG (Ki=1699 nmol/L) in inhibiting the binding of [3H]QNB. The R(−) and S (+) configurations showed positive cooperation (nH>1) with the muscarinic receptor, whereas (±)DMCPG had a negative cooperation (nH<1) relationship with the muscarinic receptor in a radio-binding assay. Both the R(−) and S(+) configurations could potentiate the effect of sub-threshold hypnotic dose of sodium pentobarbital in a dose-dependent manner (the ED50 values were 2.53 and 18.65 mg/kg, respectively), but (±)DMCPG did not display significant central depressant effects at doses from 10 to 29.15 mg/kg (P>0.05). (±)DMCPG and its optical isomers suppressed the guinea pig ileum contractile response to carbachol. The IC50 values were 7.78×10−9, 1.88×10−7, and 1.03×10−7 nmol/L, respectively. In the anti-salivation study, (±)DMCPG and its enantiomers depressed oxotremorine- induced salivation in a dose-dependent manner, and the order of potency was R(-)DMCPG (ED50=0.44 mg/kg)>(±)DMCPG (ED50=2.88 mg/kg)>S(+)DMCPG (ED50=5.05 mg/kg).Conclusion:(±)DMCPG and its optical isomers have differences in their pharmacological potencies as anticholinergic agents, and the R(−) configuration is more active than the S(+) configuration.

Studies of Bioactivity, Conformation and Pharmacokinetic Profiles of Site-Specific PEGylated Thymosin Alpha 1 Derivatives

Site-specific mono-PEGylations were performed in different conformational regions of Thymosin alpha 1 (T alpha 1) by introducing one cysteine residue into the chosen site and coupling with thiol-specific mPEG-MAL reagent. Results demonstrated that PEGylated sites and regions influenced the conformations and pharmacokinetic profiles of the peptide greatly with following order: alpha-helix, beta-turn, random coil and terminals, but little on the immunoactivity.

Poly(ethylene glycol) (PEG) Modifications and Conformational Analysis of Thymosin α 1

Results and Discussion According to the SAR results [1], the conjugating sites of Tα1 with PEG were chosen at the N-terminus, C-terminus, α-helix, β-turn, and the random coil regions. Referring to the method reported by Vanwetsswinkel et al [2,3], [Cys]Tα1 analogs (x: the chosen site) were synthesized firstly for conveniently introducing the covalent attachment mPEG-MAL into the chosen sites, and then the PEG conjugations were prepared as follows (Scheme 1) .