Chagas Disease Drug Discovery: Multiparametric Lead Optimization against Trypanosoma cruzi in Acylaminobenzothiazole Series.

Acylaminobenzothiazole hits were identified as potential inhibitors of Trypanosoma cruzi replication, a parasite responsible for Chagas disease. We selected compound 1 for lead optimization, aiming to improve in parallel its anti-T. cruzi activity (IC50 = 0.63 µM) and its human metabolic stability (human clearance = 9.57 mL/min/g). A total of 39 analogues of 1 were synthesized and tested in vitro. We established a multiparametric structure-activity relationship, allowing optimization of antiparasite activity, physicochemical parameters, and ADME properties. We identified compound 50 as an advanced lead with an improved anti-T. cruzi activity in vitro (IC50 = 0.079 µM) and an enhanced metabolic stability (human clearance = 0.41 mL/min/g) and opportunity for the oral route of administration. After tolerability assessment, 50 demonstrated a promising in vivo efficacy.

Establishing quality assurance criteria for serial dilution operations on liquid-handling equipment.

Since the advent of high-throughput screening (HTS) in the early 1990s, parallel multichannel liquid handlers have become a mainstay in every drug discovery setting. Although several peer-reviewed publications have discussed methods and criteria for stamping multiwell copies, there is very little information about establishing a standard operating procedure (SOP) for standard (microliter-level) serial dilutions of compounds used in dose-response experiments. The authors discuss the 4 main criteria any serial dilution process must pass (accuracy, precision, fold dilution, and outliers) and the process for establishing thresholds for all of these values in a compound management or biological screening laboratory. The thresholds need to be both low enough to be acceptable from a biological potency variability perspective and high enough to allow the instruments to pass the quality assurance (QA) analysis on a regular basis. In this article, the authors suggest suitable thresholds arrived at by a variety of methods, including trend analysis of QA data, survey questionnaire from the main stakeholders (screening scientists, chemists), and published criteria for single-shot stamping. A mathematical analysis of the effect of threshold values on estimated XC(50)s was performed to ensure that the variability introduced by the serial dilution step is within acceptable overall variability limits.