Effects of Plant Metabolites on Aliivibrio fischeri and Test Strains of Gastrointestinal Microbiota

Plant metabolites undergo a thorough toxicity test before becoming part of pharmaceuticals or functional food products. In vivo toxicity studies on animals are expensive and time-consuming. Moreover, they require an ethic approval and a lot of expendables. Alternative methods often involve microbial models. As a result, they reduce the number of animal test subjects on further research stages. This study tested the toxicity of several plant metabolites in vitro on Aliivibrio fischeri and gastrointestinal microbiota. The research included rutin, rosmarinic acid, trans-cinnamic acid, quercetin, kaempferol, baicalin, and wogonin (≥ 94%). These plant metabolites were isolated from callus, suspension, and root cultures of Siberian plants. Their toxic effects were tested on the bioluminescent properties of Aliivibrio fischeri. The analysis relied on the method of thin-layer chromatography. Another experiment assessed the toxic effects of these plant metabolites on Propionibacterium jensenii (B-6085), Propionibacterium freudenreichii (B-11921), Lactobacillus freudenreichii subsp. freudenreichii (B-6561), Lactobacillus plantarum (B-884), Bifidobacterium longum (AC-1257), and Bifidobacterium bifidum (AC-1779). The solutions of rutin, quercetin, wogonin, and baicalin (20% ethanol) were toxic towards A. fischeri. Kaempferol was the only metabolite that stimulated the biomass growth of lacto- and bifidobacteria. Quercetin, rutin, and trans-cinnamic acid inhibited the biomass growth of propionic bacteria. The other metabolites suppressed the negative impact of 20% ethanol without affecting the growth of the test strains. A. fischeri tests proved to be a reliable preliminary toxicity assessment of plant materials before in-vivo studies.