Comparison of Chinese licorice (Glycyrrhiza uralensis) granules and water extracts and investigation of their antibacterial activities for veterinary application

Abstract

IntroductionAlthough Chinese licorice (Glycyrrhiza uralensis) granules are widely used in the treatment of human diseases, there are few reports on its veterinary applications. Chinese licorice granules may have multiple advantages compared to its water extract obtained by decoction (tang). The procedure for making granules avoids the extraction steps, significantly reducing the medicine preparation time and making dosage measurements more accurate, thus providing the potential for broader applications. This study compared the glycyrrhizin content and antimicrobial efficacy between Chinese licorice granules and its water extract to determine whether Chinese licorice granules are a reliable alternative to water extract. MethodsThe glycyrrhizin content of Chinese licorice granules was compared to that of water extractions from Chinese licorice using qualitative thin-layer chromatography (TLC) and quantitative high-performance liquid chromatography (HPLC). The efficacy of these two Chinese licorice products was determined by in vitro antibacterial experiments. ResultsTLC analysis showed that Chinese granules had fluorescent spots in the same corresponding positions as Chinese licorice standards and the same yellow fluorescent spot as the glycyrrhizin standards. The content of glycyrrhizin in granules and water extracts was 3.288 ± 0.0376 and 2.721 ± 0.0199 mg/mL respectively as detected by HPLC. HPLC chromatographic fingerprints showed that granules had a 94.9 % similarity with the licorice standard solution, compared to a 91.5 % similarity of the water extraction. In vitro antibacterial assays proved that the granules had higher efficacy than the water extracts, which was comparable to the efficacy of standards licorice solution against Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli and Salmonella enteric. ConclusionsThe data shows that the licorice granules exhibit higher antibacterial efficacy than its water extractions. Our results suggest that Chinese licorice granules may be an alternative to its water extract for treating animals for bacterial infections.