LC-MS analysis of 13,28-epoxy-oleanane saponins in Maesa spp. extracts with antileishmanial activity

Emerging therapeutic targets for treatment of leishmaniasis

INTRODUCTION

Parasitic diseases that pose a threat to human life include leishmaniasis - caused by protozoan parasite Leishmania species. Existing drugs have limitations due to deleterious side effects like teratogenicity, high cost and drug resistance. This calls for the need to have an insight into therapeutic aspects of disease. Areas covered: We have identified different drug targets via. molecular, imuunological, metabolic as well as by system biology approaches. We bring these promising drug targets into light so that they can be explored to their maximum. In an effort to bridge the gaps between existing knowledge and prospects of drug discovery, we have compiled interesting studies on drug targets, thereby paving the way for establishment of better therapeutic aspects. Expert opinion: Advancements in technology shed light on many unexplored pathways. Further probing of well established pathways led to the discovery of new drug targets. This review is a comprehensive report on current and emerging drug targets, with emphasis on several metabolic targets, organellar biochemistry, salvage pathways, epigenetics, kinome and more. Identification of new targets can contribute significantly towards strengthening the pipeline for disease elimination.

Intravenous and subcutaneous toxicity and absorption kinetics in mice and dogs of the antileishmanial triterpene saponin PX-6518

The intravenous (IV) and subcutaneous (SC) toxicity and absorption kinetics of the antileishmanial triterpene saponin PX-6518 and its active constituents maesabalide-III and -IV were studied in mice and dogs. A high-dose wash-out study of PX-6518 at 20 mg/kg SC for 5 days and a single low-dose wash-out study at 1, 2.5 or 5 mg/kg SC and IV with follow-up until day 35 after treatment were performed in mice. Beagle dogs received three escalating doses of maesabalide-III and -IV at weekly intervals (0.01, 0.1 and 0.5 mg/kg IV and maesabalide-III was also dosed SC at 0.1, 0.2 and 0.4 mg/kg). Endpoint measurements included clinical, hematological and serum biochemical parameters. Pathology and toxicokinetic studies were performed on the dogs. Whereas the neutrophils and aspartate aminotransferase and alanine aminotransferase levels were increased in the high-dose wash-out mouse study, these parameters did not change in the low-dose wash-out study. The dogs were far more susceptible than mice to liver toxicity (hepatocellular necrosis and elevated liver enzymes) and developed a painful inflammatory reaction at the SC injection site. Toxicokinetic analysis revealed a non dose-linear systemic availability with plasma concentrations above the antileishmanial IC₅₀ after only a single dose at 0.01 mg/kg IV or 0.1 mg/kg SC. Related to the long half-life (T(1/2) 71-91 h after SC dosing), repeated dosing at weekly intervals may result in drug accumulation and enhanced toxicity. It was decided not to pursue further drug development for PX-6518 because of the hepatotoxic risk.