In Vitro Evaluation of the Antimicrobial and Immunomodulatory Activity of Culinary Herb Essential Oils as Potential Perioceutics.

Marcela Popa,Crina Kamerzan,Grațiela Grădișteanu Pircalabioru,Mariana Carmen Chifiriuc,Eliza Oprea,Coralia Bleotu,Luminița Măruțescu

doi:10.3390/antibiotics9070428

Abstract

Due to their antimicrobial, immunomodulatory, antioxidant, and regenerative activities, culinary herbs have multiple medicinal uses, among which to prevent and treat oral diseases. The whole essential oils (EOs) have multiple advantages over purified components, such as a low probability to select for antimicrobial resistance, synergic effects of different components, and multi-pharmacological activities. In this study, we aimed to evaluate essential oils from Salvia officinalis (sage), Satureja hortensis (summer savory), and Anethum graveolens (dill) using an in vitro analysis of their antimicrobial activity against Gram-positive and Gram-negative bacterial strains isolated from the oral cavity of patients with periodontitis; the assays addressed both the planktonic and biofilm growth states and used culture-based approaches. Some of the tested EOs exhibited excellent bactericidal and antibiofilm activity, being active at concentrations as low as 0.08–1.36 mg/mL. Flow cytometry was used to investigate the potential mechanisms of their antibacterial activity and confirmed that the tested EOs act by permeabilizing the bacterial membrane and by inhibiting the activity of the efflux pumps. The immunomodulatory effect of the three EOs was determined by analyzing the gene expression profiles for pro- and anti-inflammatory cytokines of the THP-1 cells. The summer savory EO induced a clear proinflammatory effect, while the others did not significantly influence the cytokines profile of the tested cells. Taken together, our results indicate that summer savory EO and, to a lesser extent, sage and dill EOs could be used to inhibit bacteria involved in oral plaque formation and to reduce the expression of genes known to contribute to the inflammatory response using cell culture assessment.

Highlights

Medicinal plants have been used for thousands of years around the globe, by around 80% of the world population, as traditional treatments for many ailments, in developing countries [1].Subsequent research has demonstrated that natural products derived from medicinal plants represent an abundant source of biologically active compounds and have been the basis for developing new chemicals for the pharmaceutical industry.Currently, one of the most serious challenges of the pharmaceutical industry is the emergence of antimicrobial resistance, which is considered by World Health Organization (WHO) as one of the top Antibiotics 2020, 9, 428; doi:10.3390/antibiotics9070428 www.mdpi.com/journal/antibioticsAntibiotics 2020, 9, 428 ten global challenges [2]
In the case of S. hortensis L., the components identified by gas chromatography-mass spectrometry (GC-MS) analysis of the volatile oil extracted from leaves were carvacrol (54.069%), γ-terpinene (26.749%), and m-cymene (7.996%)
Our study revealed that the tested essential oils (EOs) and the β-pinene analytical standard inhibited the activity of efflux pumps of S. salivarius sp. salivarius and S. acidominimas (Figure 1 and Table 2)

Summary

Introduction

Medicinal plants have been used for thousands of years around the globe, by around 80% of the world population, as traditional treatments for many ailments, in developing countries [1].Subsequent research has demonstrated that natural products derived from medicinal plants represent an abundant source of biologically active compounds and have been the basis for developing new chemicals for the pharmaceutical industry.Currently, one of the most serious challenges of the pharmaceutical industry is the emergence of antimicrobial resistance, which is considered by World Health Organization (WHO) as one of the top Antibiotics 2020, 9, 428; doi:10.3390/antibiotics9070428 www.mdpi.com/journal/antibioticsAntibiotics 2020, 9, 428 ten global challenges [2]. Subsequent research has demonstrated that natural products derived from medicinal plants represent an abundant source of biologically active compounds and have been the basis for developing new chemicals for the pharmaceutical industry. One of the most serious challenges of the pharmaceutical industry is the emergence of antimicrobial resistance, which is considered by World Health Organization (WHO) as one of the top Antibiotics 2020, 9, 428; doi:10.3390/antibiotics9070428 www.mdpi.com/journal/antibiotics. The adverse effects of currently used therapeutic agents (dysbiosis, hepato- and nephrotoxicity, and hypersensitivity reactions) has led to an increased interest in the discovery of new, natural compounds with anti-infectious and immunomodulatory activity. Essential oils (EOs), defined as volatile secondary metabolites of plants, have been extensively used in traditional medicine due to of their many different biological properties, including antimicrobial and immunomodulatory ones. EOs are a complex mixture of terpenes, terpenoids, and phenylpropanoids, but they may contain sulfur derivatives, fatty acids, and oxides [4]

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