A Validated HPLC-PDA-HRMS Method to Investigate the Biological Stability and Metabolism of Antiparasitic Triterpenic Esters.

Laura Schioppa,Fanta Fall,Sergio Ortiz,Joelle Quetin-Leclercq,Jacques H Poupaert

doi:10.3390/molecules26237154

Abstract

Pentacyclic triterpenes (PTs) are commonly found in medicinal plants with well-known antiparasitic effects. Previous research on C-3 and C-27 triterpenic esters showed effective and selective in vitro antiparasitic activities and in vivo effectiveness by parenteral routes. The aim of this study was to determine triterpenic esters’ stability in different biological-like media and the main microsomal degradation products. An HPLC-PDA method was developed and validated to simultaneously analyze and quantify bioactive triterpenic esters in methanol (LOQ: 2.5 and 1.25–100 µg/mL) and plasma (LOQ: 5–125 µg/mL). Overall, both triterpenic esters showed a stable profile in aqueous and buffered solutions as well as in entire plasma, suggesting gaining access to the ester function is difficult for plasma enzymes. Conversely, after 1 h, 30% esters degradation in acidic media was observed with potential different hydrolysis mechanisms. C-3 (15 and 150 µM) and C-27 esters (150 µM) showed a relatively low hepatic microsomal metabolism (<23%) after 1 h, which was significantly higher in the lowest concentration of C-27 esters (15 µM) (>40% degradation). Metabolic HPLC-PDA-HRMS studies suggested hydrolysis, hydroxylation, dehydration, O-methylation, hydroxylation and/or the reduction of hydrolyzed derivatives, depending on the concentration and the position of the ester link. Further permeability and absorption studies are required to better define triterpenic esters pharmacokinetic and specific formulations designed to increase their oral bioavailability.

Highlights

Neglected tropical diseases (NTDs) account for 1% of the global disease burden, and more than 1.7 billion people require treatment for at least one NTD every year
The present study aimed to investigate the stability of these promising antiparasitic triterpenic esters and their potential to target malaria and Human African Trypanosomiasis (HAT) infections
Three retention times corresponding to the beginning, the middle and the end of each peak were analyzed by HPLC-PDA-MS in ESI (-) to assess the molecular mass and spectra along the peak(s) (Supplementary Materials Figure S2)

Summary

Introduction

Neglected tropical diseases (NTDs) account for 1% of the global disease burden, and more than 1.7 billion people require treatment for at least one NTD every year. For the fifth consecutive year, NTDs threatened more than one billion people despite the global implementation after 2008 [1]. Human African Trypanosomiasis (HAT) caused by Trypanosoma brucei parasites still remains present in over 20 countries. In spite of registered cases dropping in 2015, an under-detection of cases should be considered during the reported incidence assessment [2]. Malaria, caused by Plasmodium protozoans, is the most widespread parasitic infection, with 229 million reported cases in 2019. A scale-up intervention series over the last decade helped to cut the mortality rate by 44%

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