Quillaja saponaria (Molina) Extracts Inhibits In Vitro Piscirickettsia salmonis Infections

Abstract

P. salmonis infections are the cause of major bacterial disease in salmonids in Chile, and the reason for using more antibiotics compared to other salmon-producing countries. Vaccination and antibiotics have not been efficient and new approaches are needed. The safety of Quillaja saponaria extracts was measured by cytotoxicity using flow cytometry of cytopathic and death of fish cell cultures and efficacy was assessed using in vitro infection models with pathogenic P. salmonis. Cytotoxicity was low and control of in vitro infections was achieved with all products, with protection of over 90%. Minimum inhibitory concentrations were much higher than those in the infection using cell cultures. These results suggest a dual mechanism of action where less purified extracts with a combination of saponin and non-saponin components simultaneously decrease P. salmonis infection while protecting cell lines, rather than exerting a direct antimicrobial effect. Quillaja saponins controlled in vitro infections with P. salmonis and could be considered good candidates for a new, safe and sustainable method of controlling fish bacterial infectious diseases.

Anti-Inflammatory Chilean Endemic Plants

“…Its raw saponins are used as a foaming and emulsifying agent [ 91 ]. The main uses of Quillaja saponaria extracts are as emulsifiers in cosmetics, food, and beverages, as vaccine adjuvants, and as a biocide [ 92 ]. Q. saponaria extracts involve a complex mixture of glycosides and sugar esters, mainly of the pentacyclic triterpene quillaic acid [ 54 ].…”

Evaluation of bactericidal activity of 7‐arylaminoisoquinolin‐5,8‐quinones against Piscirickettsia salmonis

“…Recently, it has been estimated that up to 10% of all culture aquatic animals are lost to infectious diseases, amounting to >10 billion USD annual losses on global scale (Evensen, 2016; Gallardo et al, 2020). Piscirickettsiosis is by far the most important disease in the Chilean salmon aquaculture (Cañon‐Jones et al, 2020; SERNAPESCA, 2019). The Salmonid Rickettsial Septicaemia (SRS) o piscirickettsiosis is caused by the Gram‐negative bacterium Piscirickettsia salmonis (Fryer & Hedrick, 2003), a fastidious intracellular facultative pathogen (Colquhoun et al, 2008; Mancilla et al, 2016; Rozas & Enriquez, 2014; Rozas‐Serri, 2022).…”

“…Infected fish often have skin lesions that range from small areas of raised scales to nodules and shallow haemorrhagic ulcers. Low levels of haematocrit indicate severe anaemia (Cañon‐Jones et al, 2020; Mauel & Miller, 2002; Rozas & Enriquez, 2014). Antibiotics have been widely used in the prevention and treatment of this infectious and contagious disease (Miranda, 2012).…”

“…Piscirickettsiosis is by far the most important disease in the Chilean salmon aquaculture (Cañon-Jones et al, 2020;SERNAPESCA, 2019).…”

“…Infected fish often have skin lesions that range from small areas of raised scales to nodules and shallow haemorrhagic ulcers. Low levels of haematocrit indicate severe anaemia (Cañon-Jones et al, 2020;Mauel & Miller, 2002;Rozas & Enriquez, 2014).…”