Beneficial Effects of Laurel (Laurus nobilis L.) and Myrtle (Myrtus communis L.) Extract on Rat Health

Polyphenols of Laurel and Myrtle exhibit structural diversity, which affects bioavailability, metabolism, and bioactivity. The gut microbiota plays a key role in modulating the production, bioavailability and, thus the biological activities of phenolic metabolites, particularly after the intake of food containing high-molecular-weight polyphenols. The aim of this study was to investigate whether the polyphenolic components of Laurel and Myrtle aqueous extract have beneficial effects on rat health. The growth of lactic acid bacteria (LAB), β-glucuronidase, β-glucosidase, β-galactosidase activity, pH value, body weight change and food efficacy ratio after intragastric treatment of rats with Laurel and Myrtle extract at doses of 50 and 100 mg/kg for two weeks were investigated. The endogenous populations of colonic probiotic bacteria (Lactobacilli and Bifidobacteria) were counted on selective media. According to the obtained data, Laurel extract in the applied dose of 50 and 100 and Myrtle extract (100 mg/kg) positively affects the rats health by increasing the number of colonies of Lactobacilli and Bifidobacteria compared to the control group, causes changes in glycolytic enzymatic activity and minor change in antioxidative tissue activity. In addition, high doses of Laurel increase food efficiency ratio, while Myrtle has the same effect at a lower dose.