Polyphenol content and modulatory activities of some tropical dietary plant extracts on the oxidant activities of neutrophils and myeloperoxidase.

Cesar N Tsumbu,Cesar N Tsumbu,Didier Serteyn,Monique Tits,Ange Mouithys-Mickalad,Thierry Franck,Ginette Deby-Dupont,Stephane Kohnen,Luc Angenot,Michel Frederich

doi:10.3390/ijms13010628

Cesar N Tsumbu, Cesar N Tsumbu + Show 8 more

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https://doi.org/10.3390/ijms13010628

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Abstract

Young leaves of Manihot esculenta Crantz (Euphorbiaceae), Abelmoschus esculentus (Malvaceae), Hibiscus acetosella (Malvaceae) and Pteridium aquilinum (Dennstaedtiaceae) are currently consumed as green vegetables by peoples in sub-Saharan Africa, Latin America, Asia and their migrants living in Western Europe. Sub-Saharan peoples use Manihot, Abelmoschus and Hibiscus also in the folk medicine to alleviate fever and pain, in the treatment of conjunctivitis, rheumatism, hemorrhoid, abscesses, ... The present study investigates the effects of aqueous extracts of those plants on the production of reactive oxygen species (ROS) and the release of myeloperoxidase (MPO) by equine neutrophils activated with phorbol 12-myristate 13-acetate (PMA). The ROS production was measured by lucigenin-enhanced chemiluminescence (CL), and the release of total MPO by an ELISA method. The study also investigates the effect of the extracts on the activity of MPO by studying its nitration activity on tyrosine and by using a new technique called SIEFED (Specific Immunological Extraction Followed by Enzymatic Detection) that allows studying the direct interaction of compounds with the enzyme. In all experiments, the aqueous extracts of the plants developed concentration-dependent inhibitory effects. A moderate heat treatment did not significantly modify the inhibitory capacity of the extracts in comparison to not heated ones. Total polyphenol and flavonoid contents were determined with an HPLC-UV/DAD analysis and a spectroscopic method using Folin-Ciocalteu reagent. Some polyphenols with well-known antioxidant activities (caffeic acid, chlorogenic acid, hyperoside, rosmarinic acid and rutin) were found in the extracts and may partly explain the inhibitory activities observed. The role of those dietary and medicinal plants in the treatment of ROS-dependent inflammatory diseases could have new considerations for health.

Highlights

Neutrophils ingest infectious agents by phagocytosis and kill them by proteolysis and reactive nitrogen and oxygen species (RNOS/reactive oxygen species (ROS)) produced by oxidant enzymes such as myeloperoxidase (MPO) and others
The cell viability as checked by the Trypan blue exclusion test [36] was ≥96% for the phosphate buffered saline (PBS) control and the plant extracts at concentrations from 0.1 to 10 μg/mL, indicating no cytotoxicity towards neutrophils
The effects on the total ROS produced by equine neutrophils stimulated with phorbol 12-myristate 13-acetate (PMA) were studied with a lucigenin-enhanced CL assay

Summary

Introduction

Neutrophils ingest infectious agents by phagocytosis and kill them by proteolysis and reactive nitrogen and oxygen species (RNOS/ROS) produced by oxidant enzymes such as myeloperoxidase (MPO) and others. When NO2− is the electron donor for the first step, it is oxidized into NO2 [2,3] responsible for nitrations, especially for tyrosine [5,6]

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