Mixtures of Scutellaria baicalensis and Glycyrrhiza L. Extracts as Antibacterial and Antiviral Agents in Active Coatings

Magdalena Ordon,Anna Schmidt,Małgorzata Mizielińska,Xymena Stachurska,Paweł Nawrotek

doi:10.3390/coatings11121438

Magdalena Ordon, Anna Schmidt + Show 3 more

Open Access

https://doi.org/10.3390/coatings11121438

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Abstract

The aim of this study was to develop active packaging materials covered in active coatings (offering antibacterial and antiviral properties) that contain selected plant extracts. In addition, the synergistic effect of the active substances in these extracts was also analysed. The results of the study demonstrated that Scutellaria baicalensis and Glycyrrhiza L. extracts (two of six analysed plant extracts) were the most active agents against selected Gram-positive and Gram-negative bacterial strains. Additionally, the synergistic effect of S. baicalensis and Glycyrrhiza L. extracts was noted, meaning that the effect of these two plant extract mixtures on Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas syringae growth was higher than the activity of individual pure extracts. Mixtures of the extracts were introduced into the coating carrier. A polyethylene (PE) foil was then coated with active layers containing mixtures of S. baicalensis and Glycyrrhiza L. extracts as antimicrobial agents. The results of this research showed that all of the active coatings had a bacteriolytic effect on B. subtilis and a bacteriostatic effect on S. aureus cells. The coatings were found to be inactive against E. coli and P. syringae cells. This means that the coatings could be used as internal coatings to preserve food products against Gram-positive bacteria that may be responsible for food spoilage. The results of this study also demonstrated that the coatings were highly active against phage phi 6 phage particles, used as SARS-CoV-2 surrogate. This means that the coatings could be used as external coatings to limit the spread of SARS-CoV-2 and pathogenic Gram-positive bacteria via human hands.

Highlights

Hippocrates taught the art of healing through the use of plant-based medicines
Comparing the dry mass of Glycyrrhiza L. and S. baicalensis, it was noted that the S. baicalensis dry mass was only 8.35% lower than the Glycyrrhiza L. dry mass extract (Table 1)
Our findings proved that there was a synergistic effect between Glycyrrhiza L. and S. baicalensis extracts, as mixtures of these two extracts were more active than pure extracts

Summary

Introduction

Hippocrates taught the art of healing through the use of plant-based medicines. He used plants and their extracts to treat diseases around 460–370 BC. The created coatings or active films can be used to preserve food products and increase their shelf life as active packaging [2,4,5] These active coatings are typically obtained using biopolymers derived from many natural plants, such as polysaccharides with the addition of active compounds, such as plant/herb extracts. An excellent example of an transparent, odourless coating (with antibacterial properties) containing plant extracts as active substances is the coatings offered in a previous study carried out by the authors [2]. These coatings were highly active against selected bacteria leading to them being an ideal internal layer for active packaging. Supermarkets could develop additional health safety measures, e.g., cardboard/ paper bags or foil bags coated with an antiviral and antibacterial external layer [2]

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