Influence of Botanical Origin and Chemical Composition on the Protective Effect against Oxidative Damage and the Capacity to Reduce In Vitro Bacterial Biofilms of Monofloral Honeys from the Andean Region of Ecuador.

Marilyn García-Tenesaca,Irina M Villacrés Granda,Eduardo Tejera,Eillen S Navarrete,Francesca Giampieri,Gabriel A Iturralde,José M Alvarez-Suarez,Maurizio Battino,Pablo Beltrán-Ayala

doi:10.3390/ijms19010045

Abstract

Three types of monofloral honey from the Andean regions of Ecuador (Avocado, Eucalyptus, and Rapeseed honey) were analyzed to determine their floral origin, physicochemical parameters, chemical composition, antioxidant capacity, and their capacity to reduce in vitro bacterial biofilms. The chemical composition varied considerably depending on floral origin. The highest values of bioactive compounds were found in Avocado honey, classified as dark amber in color, while the lowest values were found in Eucalyptus honey followed by Rapeseed honey, both classified as extra light amber. When compared to Eucalyptus and Rapeseed honey, Avocado honey showed a more effective superoxide scavenging activity, chelating metal ions capacity, and a higher ability to protect human erythrocyte membranes against lipid peroxidation. For antimicrobial activity, the hydrogen peroxide content and the capacity to inhibit the biofilm formation, and to remove preformed biofilm from Staphylococcus aureus and Klebsiella pneumoniae was determined. Avocado honey showed the highest values of hydrogen peroxide content, as well as the highest capacity to reduce in vitro bacterial biofilms. A correlation between color vs. phenolics content vs. superoxide scavenging activity vs. chelating metal ions capacity, and the capacity to protect human erythrocyte membranes against lipid peroxidation was found.

Highlights

Humankind has used honey since ancient times, firstly attracted by its sweet taste, and subsequently by the medical properties that have been attributed to it throughout the ages
According to the colour analysis, Avocado honey could be classified as dark amber, which is in line with previously reported values for this honey type [7,8], while Eucalyptus honey could be classified as extra light amber
Rapeseed honey was classified as extra light amber, which is within the range of the colour values previously reported for this monofloral honey [10,11,12]

Summary

Introduction

Humankind has used honey since ancient times, firstly attracted by its sweet taste, and subsequently by the medical properties that have been attributed to it throughout the ages. Honey is a supersaturated solution of sugar that is produced by Apis mellifera bees from the nectar collected from flowers, secretions of living parts of plants, or excretions of plant-sucking insects. These secretions are collected by bees and transformed by combining them with specific substances from their own deposits and leaving them in honeycombs to ripen and mature (EU Council, 2002). The chemical composition of honey makes it a complex natural mixture of chemical compounds allowing it to show important biological properties, such as the ability to promote wound healing [2] and its antimicrobial, anti-inflammatory, and antioxidant capacity [3]. The antioxidant capacity has been associated with its content of antioxidant compounds, such as polyphenols [3], while its antimicrobial properties have been mainly associated with its osmotic properties, as well as the presence of hydrogen peroxide and of other minor non-peroxide compounds, such as polyphenols and a particular protein, known as defensin-1 [2,5]

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