Almond Skin Extracts Abrogate HSV-1 Replication by Blocking Virus Binding to the Cell.

Carlo Bisignano,Rosamaria Pennisi,Giuseppina Mandalari,Antonella Smeriglio,Maria Pizzo,Domenico Trombetta,Maria Sciortino

doi:10.3390/v9070178

Abstract

The aim of the present research was to determine the effect of almond skin extracts on herpes simplex virus 1 (HSV-1) replication. Drug-resistant strains of HSV frequently develop following therapeutic treatment. Therefore, the discovery of novel anti-HSV drugs deserves great effort. Here, we tested both natural (NS) and blanched (BS) polyphenols-rich almond skin extracts against HSV-1. HPLC analysis showed that the prevalent compounds in NS and BS extracts contributing to their antioxidant activity were quercetin, epicatechin and catechin. Results of cell viability indicated that NS and BS extracts were not toxic to cultured Vero cells. Furthermore, NS extracts were more potent inhibitors of HSV-1 than BS extracts, and this trend was in agreement with different concentrations of flavonoids. The plaque forming assay, Western blot and real-time PCR were used to demonstrate that NS extracts were able to block the production of infectious HSV-1 particles. In addition, the viral binding assay demonstrated that NS extracts inhibited HSV-1 adsorption to Vero cells. Our conclusion is that natural products from almond skin extracts are an extraordinary source of antiviral agents and provide a novel treatment against HSV-1 infections.

Highlights

Almond skins represent 4–8% of the total shelled almond weight.In peeled almonds, they are industrially removed by hot water blanching, which results in a substantial loss of bioactive compounds in the blanch water [1]
We have previously demonstrated that polyphenols from almond skin are bioaccessible in the gastric and small intestinal compartment in vitro, and their release is affected by the food matrix, where the skin is incorporated [5]
Amongst the polyphenols mostly identified in the current extract, epicatechin was the strongest one, possessing the lowest EC50 among polyphenols tested in the DPPH assay, followed by quercetin, catechin, protocatechuic acid and kaempferol [33]

Summary

Introduction

Almond skins ( referred as almond bran) represent 4–8% of the total shelled almond weight. In peeled almonds, they are industrially removed by hot water blanching, which results in a substantial loss of bioactive compounds in the blanch water [1]. We have previously demonstrated that polyphenols from almond skin are bioaccessible in the gastric and small intestinal compartment in vitro, and their release is affected by the food matrix, where the skin is incorporated [5]. We have previously demonstrated neuroprotective effects of almond skins in an experimental spinal cord injury model and a reduction of oxidative stress and inflammation in an experimental model of inflammatory bowel disease after treatment with natural almond skins [10,11].

Objectives

Methods

Discussion

Conclusion