Preliminary Assessment of the Mucosal Toxicity of Tea Tree (Melaleuca alternifolia) and Rosemary (Rosmarinus officinalis) Essential Oils on Novel Porcine Uterus Models.

Martina Bertocchi,Diana G Scorpio,Antonella Rigillo,Monica Forni,Alberto Elmi,Maria Laura Bacci,Camilla Aniballi,Giuliano Bettini,Domenico Ventrella,Maurizio Scozzoli

doi:10.3390/ijms21093350

Abstract

Antimicrobial resistance, an ever-growing global crisis, is strongly linked to the swine production industry. In previous studies, Melaleuca alternifolia and Rosmarinus officinalis essential oils have been evaluated for toxicity on porcine spermatozoa and for antimicrobial capabilities in artificial insemination doses, with the future perspective of their use as antibiotic alternatives. The aim of the present research was to develop and validate in vitro and ex vivo models of porcine uterine mucosa for the evaluation of mucosal toxicity of essential oils. The in vitro model assessed the toxicity of a wider range of concentrations of both essential oils (from 0.2 to 500 mg/mL) on sections of uterine tissue, while the ex vivo model was achieved by filling the uterine horns. The damage induced by the oils was assessed by Evans Blue (EB) permeability assay and histologically. The expression of ZO-1, a protein involved in the composition of tight junctions, was assessed through immunohistochemical and immunofluorescence analysis. The results showed that low concentrations (0.2–0.4 mg/mL) of both essential oils, already identified as non-spermicidal but still antimicrobial, did not alter the structure and permeability of the swine uterine mucosa. Overall, these findings strengthen the hypothesis of a safe use of essential oils in inseminating doses of boar to replace antibiotics.

Highlights

Antimicrobial resistance represents a global crisis strongly affecting public health, animal health & welfare and food security, and an integrated “One Health” response is essential to avoid this universal threat [1]
Given the increasing need to reduce the use of antibiotics, Elmi and colleagues proposed the use of essential oils of Melaleuca alternifolia and Rosmarinus officinalis as antimicrobial agents in porcine inseminating doses, as an alternative to the antibiotics used in semen extenders
The essential oils (EOs) of M. alternifolia (Ma) and R. officinalis (Ro) used in the present study were supplied by APA-CT S.r.l. (Via Sacco Nicola, 22, 47122, Forlì, Italy) and their chemo-characterization was previously reported by the authors in the aforementioned toxicity studies [29,30]

Summary

Introduction

Antimicrobial resistance represents a global crisis strongly affecting public health, animal health & welfare and food security, and an integrated “One Health” response is essential to avoid this universal threat [1]. The use of antibiotics in food-producing animals plays a pivotal role as major driving force behind the rise in the prevalence of antibiotic resistance [2,3]. Antimicrobial agents are essential components of semen extenders [5]. A major concern is the generation of antibiotic-resistant bacterial strains in AI stations, triggered by the intense use of antibiotics in semen extenders. The progressive ban of certain antibiotics for veterinary use [9], reinforces the need for alternative antimicrobial strategies in boar semen extenders [5]. Natural compounds, and in particular essential oils (EOs) were evaluated on semen of different species for their antioxidant and antimicrobial proprieties [14,15,16,17]

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Conclusion