Imidazoline- and Benzamidine-Based Trypanosome Alternative Oxidase Inhibitors: Synthesis and Structure-Activity Relationship Studies.

The trypanosome alternative oxidase (TAO), a mitochondrial enzyme involved in the respiration of the bloodstream form trypomastigotes of Trypanosoma brucei, is a validated drug target against African trypanosomes. Earlier series of TAO inhibitors having a 2,4-dihydroxy-6-methylbenzoic acid scaffold ("head") and a triphenylphosphonium or quinolin-1-ium cation as a mitochondrion-targeting group ("tail") were shown to be nanomolar inhibitors in enzymatic and cellular assays. We investigated here the effect of different mitochondrion-targeting cations and other scaffold modifications on the in vitro activity of this class of inhibitors. Low micromolar range activities were obtained, and the structure-activity relationship studies showed that modulation of the tail region with polar substituents is generally detrimental to the enzymatic and cellular activity of TAO inhibitors.

Relamorelin Reduces Vomiting Frequency and Severity and Accelerates Gastric Emptying in Adults With Diabetic Gastroparesis.

BACKGROUND & AIMS: Gastroparesis is an important complication of diabetes. We investigated the effects of relamorelin (a pentapeptide-selective agonist of the ghrelin receptor that speeds gastric emptying in patients with diabetes) in patients with diabetic gastroparesis. METHODS: We performed a double-blind trial of 204 patients (78% Caucasian; 67% female; mean age, 55 y; 88% with type 2 diabetes) with diabetic gastroparesis with moderate to severe symptoms and delayed gastric emptying at 27 clinical centers, from June 2012 until August 2013. Patients were assigned randomly (1:1:1) to groups given placebo or subcutaneous relamorelin 10 µg once or twice daily. The primary end point was the half-time of gastric emptying. Secondary end points included nausea, abdominal pain, bloating, early satiety, as well as the composite score of these 4 subjective symptoms and vomiting frequency and severity. RESULTS: Twice-daily relamorelin significantly accelerated gastric emptying (P < .03) and reduced vomiting frequency (by ∼60%) and severity vs placebo (P ≤ .033). Compared with placebo, relamorelin did not improve other gastrointestinal symptoms, such as abdominal pain and satiety. In the 119 patients (58.3%) with baseline vomiting, twice-daily relamorelin significantly reduced the half-time of gastric emptying and vomiting, as well as nausea, abdominal pain, bloating, and early satiety compared with placebo (composite score, P = .043). No overall safety concerns were identified. CONCLUSIONS: In a clinical trial of patients with diabetic gastroparesis, relamorelin (10 µg twice daily) significantly accelerated gastric emptying and significantly reduced vomiting, compared with placebo. Among patients with baseline vomiting, relamorelin had prokinetic effects and significantly reduced vomiting and also improved other symptoms of diabetic gastroparesis compared with placebo. ClincialTrials.gov number: NCT01571297.