Synthesis and gastrointestinal prokinetic activity of novel benzamide derivatives with amphoteric side chains

Synthesis and pharmacological properties of novel hydrophilic 5-HT4 receptor antagonists

Serotonin (5-hydroxytryptamine, 5-HT) is an important signalling molecule in the human body. The 5-HT(4) serotonin receptor, coupled to the G protein G(s), plays important physiological and pathophysiological roles in the heart, urinary bladder, gastrointestinal tract and the adrenal gland. Both 5-HT(4) antagonists and agonists have been developed in the aim to treat diseases in these organs. 5-HT(4) agonists might have beneficial effects in the central nervous system (CNS) and therefore, 5-HT(4) antagonists might cause CNS side effects. In this study, we have developed new amphoteric 5-HT(4) antagonists. A series of cyclic indole amide derivatives possessing an oxazine ring and a piperidine alkane carboxylic acid side chain and the corresponding prodrug esters were synthesized and their binding to 5-HT(4) receptors and antagonist properties were evaluated. In addition, an indole ester without the oxazine ring and the corresponding indole amide derivatives were also tested. Octanol-water distribution (LogD(Oct7.4)) was tested for some of the synthesized ligands. The main structure-affinity characteristics of the 5-HT(4) compounds tested were that the prodrug esters show higher affinity than their corresponding free acids, indole esters show higher affinity than the corresponding amides and ligands containing the oxazine ring in the indole skeleton show higher affinity than indole derivatives not containing the ring. One representative prodrug ester and its corresponding free acid were tested for binding on a panel of receptors and showed preserved selectivity for the 5-HT(4) receptor. These new molecules may be useful to target peripheral 5-HT(4) receptors.

Effect of itopride on gastric emptying in longstanding diabetes mellitus

Delayed gastric emptying (GE) occurs in 30-50% of patients with longstanding type 1 or 2 diabetes, and represents a major cause of morbidity. Current therapeutic options are limited. We aimed at evaluating the effects of itopride on GE in patients with longstanding diabetes. Twenty-five patients (20 type 1, 5 type 2; 10 males, 15 females; mean age 45.2 +/- 2.7 years; body mass index 27.5 +/- 0.9 kg m(-2); duration of diabetes 20.2 +/- 2.4 years) were enrolled in a double-blind, placebo-controlled, randomized, crossover trial. Subjects received both itopride (200 mg) and placebo t.i.d. for 7 days, with a washout of 7-14 days. GE (scintigraphy), blood glucose (glucometer) and upper gastrointestinal (GI) symptoms (questionnaire) were measured following each treatment period. The test meal comprised 100 g ground beef (99mTc-sulphur colloid) and 150 mL of 10% dextrose [67Ga-ethylenediaminetetraacetic acid (EDTA)]. There was a slight trend for itopride to accelerate both solid (P = 0.09) and liquid (P = 0.09) GE. With itopride treatment, the emptying of both solids and liquids tended to be more accelerated, as the emptying with placebo was slower (solids: r = 0.39, P = 0.057; liquids: r = 0.44, P < 0.03). Twelve (48%) patients had delayed solid and/or liquid GE on placebo and in this group, itopride modestly accelerated liquid (P < 0.05), but not solid (P = 0.39), emptying. Itopride had no effect on mean blood glucose during the GE measurement (placebo: 9.8 +/- 0.6 mmol L(-1) vs itopride: 9.6 +/-0.6 mmol L(-1)), or GI symptoms (placebo: 1.4 +/- 0.4 vs itopride: 1.8 +/- 0.5). Itopride, in a dose of 200 mg t.i.d. for 7 days, tends to accelerate GE of liquids and solids in longstanding diabetes. The magnitude of this effect appears to be modest and possibly dependent on the rate of GE without itopride.

Structure-activity relationships of xanthene carboxamides, novel CCR1 receptor antagonists

The structure-activity relationships of xanthene carboxamide derivatives on the CCR1 receptor binding affinity and the functional antagonist activity were described. Previously, we reported a quaternarized xanthen-9-carboxamide 1 as a potent human CCR1 receptor antagonist that was derived from a xanthen-9-carboxamide lead 2a. Further derivatization of 2a focusing on installing an additional substituent into the xanthene ring resulted in the identification of 2b-1 with IC(50) values of 1.8nM and 13nM in the binding assay using human CCR1 receptors transfected CHO cells and in the functional assay using U937 cells expressing human CCR1 receptors, respectively.

An improved synthesis of butyl 4-[(4-amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetate (AU-224)

A new and facile route for the synthesis of the novel gastrointestinal prokinetic butyl 4-[(4-amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetate (1b), which exhibited potent gastro- and colon-prokinetic activities by oral administration without significant side effects, was established. The key intermediate, butyl 4-amino-1-piperidineacetate (16), was prepared from commercially available 4-amino-1-benzylpiperidine (2) in a high yield with four steps. Compound 1b was prepared by condensation of commercially available 4-amino-5-choloro-2-methoxybenzoic acid (7) with 16 in 84% yield. This improved synthetic route was appropriate for large-scale synthesis of 1b.