Disclosing the bioactive metabolites involved in the in vitro anthelmintic effects of salt-tolerant plants through a combined approach using PVPP and HPLC-ESI-MSn

Marta Oliveira,Eulogio J Llorent-Martínez,Caroline Sprengel Lima,Luísa Custódio,Setha Ketavong,Hervé Hoste

doi:10.1038/s41598-021-03472-9

Abstract

Strategies to reduce dependence on synthetic drugs for the treatment of gastrointestinal nematodes (GIN) infections in ruminants include the search for novel anthelmintic scaffolds on plants, yet salt-tolerant plants remain overlooked. This study aims to evaluate the in vitro anthelmintic properties of selected salt-tolerant plants against GIN, and identify the potential bioactive secondary metabolites involved. For that purpose, 80% acetone/water extracts were prepared from dried biomass of aerial organs of nine salt-tolerant plant species and tested against Haemonchus contortus and Trichostrongylus colubriformis by the Larval Exsheathment Inhibition Assay (LEIA) and Egg Hatching Inhibition Assay (EHIA). Pistacia lentiscus, Limoniatrum monopetalum, Cladium mariscus and Helychrisum italicum picardi were the most active in both GIN and life stages. To investigate the role of polyphenols in the anthelmintic activity, four selected extracts were treated with polyvinylpolypyrrolidone (PVPP), and non-treated and treated samples were further characterized by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn). While polyphenols seem responsible for the EHIA properties, they are partially accountable to LEIA results. Several phenolics involved in the anthelmintic effects were identified and discussed. In sum, these species are rich sources of anthelmintic compounds and, therefore, are of major interest for nutraceutical and/or phytotherapeutic applications against GIN in ruminants.

Highlights

Strategies to reduce dependence on synthetic drugs for the treatment of gastrointestinal nematodes (GIN) infections in ruminants include the search for novel anthelmintic scaffolds on plants, yet salt-tolerant plants remain overlooked
A lower combined Total phenolic content (TPC) value was detected in P. coronopus leaves and flowers extracts of different polarities (72.1 mg gallic acid equivalents (GAE) g−1 dry weight (DW)) but increased Total flavonoid content (TFC) levels (282.8 mg rutin g−1 DW)28
To the best of our knowledge, this study explores for the first time the in vitro anthelmintic properties of eight salt-tolerant species, namely H. italicum subsp. picardi, I. crithmoides, C. soldanela, C. mariscus, M. marina, P. coronopus, L. monopetalum, and C. mar‐ itima, against two GIN species and life stages

Summary

Introduction

Strategies to reduce dependence on synthetic drugs for the treatment of gastrointestinal nematodes (GIN) infections in ruminants include the search for novel anthelmintic scaffolds on plants, yet salt-tolerant plants remain overlooked. A wide number of extremophile plants, including salt-tolerant species, occur in the Mediterranean a rea13 They are adapted to harsh environmental conditions, such as high sunlight exposure, UV radiation, drought, and salinity. This group of plants is still widely unexplored in the scope of veterinary parasitology In this context, the aims of this study were (1) to evaluate the in vitro anthelmintic properties of selected Mediterranean salt-tolerant plant species against L3 larvae exsheathment and egg hatching processes of H. contortus and T. colubiformis; (2) to explore the overall role of polyphenols in the anthelmintic activity, and (3) to compare the phytochemical composition determined by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn) of selected extracts, treated or not with poly-(poly)vinylpolirrilodine (PVPP), a polyphenol-binding agent

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