Identification and accumulation of phenolic compounds in the leaves and bark of Salix alba (L.) and their biological potential.

Ewelina Piątczak,Elżbieta Płuciennik,Joanna Kolniak-Ostek,Monika Dybowska,Katarzyna Kośla,Urszula Kalinowska-Lis

doi:10.3390/biom10101391

Ewelina Piątczak, Elżbieta Płuciennik + Show 4 more

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https://doi.org/10.3390/biom10101391

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Abstract

The study examines the phenolic compounds in hydromethanolic extracts of Salix alba (L.) leaves and bark as well as their antioxidant activity and cytotoxic potential. UPLC-PDA-Q/TOF-MS analysis showed a total of 29 phenolic compounds in leaves and 34 in bark. Total phenolic compound content was 5575.96 mg/100 g of dry weight (DW) in leaves and 2330.31 mg/100 g DW in bark. The compounds were identified as derivatives of phenolic acids (seven in leaves and five in bark), flavanols and procyanidins (eight in leaves and 26 in bark) and flavonols (14 in leaves and three in bark). Both extracts exhibited strong antioxidant potential, assessed by radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), but the bark extract was even stronger than the ascorbic acid used as a standard. The cytotoxicity of both extracts was evaluated against human skin fibroblasts and human epidermal keratinocytes cell lines using the Presto Blue cell viability assay. The keratinocytes were more resistant to tested extracts than fibroblasts. The leaf and bark extracts at concentrations which exhibited antioxidant activity were also not toxic against the keratinocyte cell line. Thus, S. alba extracts, especially the leaf extract, offer promise as a nontoxic natural antioxidant, in cosmetic products or herbal medicines, and as a source of bioactive secondary metabolites.

Highlights

The last few years have seen a growth in the need for natural drugs obtained from medicinal plants as an alternative to synthetic products [1]
Twenty-nine phenolic compounds were identified in the leaf extracts and 35 in the bark extracts
Extracts from Salix sp. are commonly used for treatment, mainly due to salicin content, the phytochemical profiles of polyphenol compounds in white willow leaves and bark extracts appear to have a potentially beneficial influence on human health due to the presence of quercetin glycosides, monomeric, dimeric and trimeric flavan-3-ol derivatives, including B-type procyanidins, as well as caffeoylquinic pseudodepsides. These specialized secondary plant metabolites are known to exhibit a wide range of biological activities

Summary

Introduction

The last few years have seen a growth in the need for natural drugs obtained from medicinal plants as an alternative to synthetic products [1]. Clinical studies have shown that some herbal medicines are better tolerated by patients and show fewer side effects than synthetic derivatives [3]. Willow bark extract has been used for thousands of years as an analgesic, antipyretic and anti-inflammatory agent. Hippocrates recommended chewing willow bark for patients suffering from fever, inflammation and pain [4]. Willow bark is used to treat many different types of pain, such as rheumatic pain, back pain, toothache, as well as menstrual cramps. It is used to relieve fever, sore throat, headache and flu, mainly due to the presence of salicin, which is a natural nonselective COX-1 and COX-2 inhibitor [5]

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