Integrated Analysis of COX-2 and iNOS Derived Inflammatory Mediators in LPS-Stimulated RAW Macrophages Pre-Exposed to Echium plantagineum L. Bee Pollen Extract

Eduarda Moita,Raúl Domínguez-Perles,Nieves Baenas,Luís R Silva,Paula B Andrade,Federico Ferreres,Patrícia Valentão,Angel Gil-Izquierdo,Carla Sousa,Sayuri Miyamoto

doi:10.1371/journal.pone.0059131

Abstract

Oxidative stress and inflammation play important roles in disease development. This study intended to evaluate the anti-inflammatory and antioxidant potential of Echium plantagineum L. bee pollen to support its claimed health beneficial effects. The hydromethanol extract efficiently scavenged nitric oxide (•NO) although against superoxide (O2 •−) it behaved as antioxidant at lower concentrations and as pro-oxidant at higher concentrations. The anti-inflammatory potential was evaluated in LPS-stimulated macrophages. The levels of •NO and L-citrulline decreased for all extract concentrations tested, while the levels of prostaglandins, their metabolites and isoprostanes, evaluated by UPLC-MS, decreased with low extract concentrations. So, E. plantagineum bee pollen extract can exert anti-inflammatory activity by reducing •NO and prostaglandins. The extract is able to scavenge the reactive species •NO and O2 •− and reduce markers of oxidative stress in cells at low concentrations.

Highlights

Bee pollen, used as a dietary supplement, is promoted as a health food with a wide range of nutritional and therapeutic properties
Phenolic profile The phenolic profile of E. plantagineum bee pollen hydromethanolic extract was established by HPLC-DAD (Figure 2)
A dual behaviour was seen against O2N2 generated by the phenazine methosulphate (PMS)/NADH system: until 0.8 mg mL21 a dose-dependent scavenging effect was observed, but a pro-oxidant response was noticed with higher concentrations (Figure 3)

Summary

Introduction

Bee pollen, used as a dietary supplement, is promoted as a health food with a wide range of nutritional and therapeutic properties. Echium plantagineum L., native to southern Europe, is known by its characteristic flower with a purple corolla and two protruding stamens and one stigma, being commonly known as purple viper’s bugloss (Figure 1). This species is visited by bees especially at the end of the floral period and dark blue bee pollen pellets (Figure 1) are collected and commercialized [1]. From a nutritional point of view, pollen is a good source of proteins and essential amino acids. The total amino acids content in E. plantagineum pollen can reach 32% [3]. Other metabolites previously described in E. plantagineum are phenolic compounds [1,4]

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