Since December 2019, a global pandemic has been observed, caused by the emergence of a new coronavirus, SARS CoV-2. The latter is responsible for the respiratory disease, COVID-19. The infection is also characterized by renal, hepatic, and gastrointestinal dysfunctions suggesting the spread of the virus to other organs. A dysregulated immune response was also reported. To date, there is no measure to treat or prevent SARS CoV-2 infection. Additionally, as gut microbiota composition is altered in patients with COVID-19, alternative therapies using probiotics can be considered to fight SARS CoV-2 infection. This review aims at summarizing the current knowledge about next-generation probiotics (NGPs) and their benefits in viral respiratory tract infections and in COVID-19. We describe these bacteria, highlighted by studies using metagenomic approaches. In addition, these bacteria generate metabolites such as butyrate, desaminotyrosine, and secondary bile acid, suggested to prevent viral respiratory infections. Gut microbial metabolites transported via the circulation to the lungs could inhibit viral replication or improve the immune response against viruses. The use of probiotics and/or their metabolites may target either the virus itself and/or the immunologic process. However, this review showed that more studies are needed to determine the benefits of probiotics and metabolite products in COVID-19.

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Aim The purpose of this study was to conduct phytochemical analysis of sea buckthorn pulp oil and to evaluate the antimicrobial, anti‐biofilm and antioxidant activities of its mouthwash form. Methods and Results Fatty acid composition of the sea buckthorn pulp oil was determined by GC‐MS analysis, which revealed that, mono‐unsaturated fatty acid, palmitoleic acid and saturated fatty acid, palmitic acid, were the major constituents. The antimicrobial and the anti‐biofilm capacities of sea buckthorn pulp oil mouthwash form were evaluated against Streptococcus gordonii, Porphyromonas gingivalis, Actinomyces viscosus and Candida albicans, according to the European Norms, and the Biofilm Ring Test®, respectively. These activities were then compared with those of chlorhexidine and herbal mouthwashes. The sea buckthorn‐based mouthwash was bactericidal against S. gordonii and P. gingivalis, bacteriostatic against A. viscosus and showed no antifungal effect. Regardless of the strains used, complete inhibition of biofilm formation was achieved. The antioxidant activity of this experimental mouthwash was also assessed by DPPH and NBT assays. Conclusion Sea buckthorn mouthwash showed anti‐biofilm activities against select single and multiple oral bacterial species. Significance and Impact of the Study In this study, a mouthwash derived from sea buckthorn (Hippophae rhamnoides) pulp oil has been experimented, for the first time, in order to overcome the problem of a large number of available synthetic mouthwashes which have side effects on teeth, gums and mucous membranes. This mouthwash seemed to be a suitable alternative for a preventive agent for periodontal inflammation.