In vivo and in vitro evaluation of antibacterial and anti-inflammatory activities of extraction of crude saponin isolated from licorice roots against Streptococcus pneumoniae.

Abstract

Objectives: Antibiotic resistance is a global health concern, prompting exploration of alternative therapies, including medicinal herbs. Glycyrrhiza glabra (licorice) contains saponins, which may possess antibacterial and antioxidant properties. This study aims to evaluate the antibacterial and antioxidant activities of saponin extracted from G. glabra and assess its safety and immunomodulatory effects in vivo.

Methods: Saponin was isolated from licorice roots using a Soxhlet apparatus with 70 % ethanol as the extraction solvent over 168 h. Antioxidant activity of the extract was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging assay and ferric reducing antioxidant power (FRAP) assay. Antibacterial activity toward Streptococcus pneumoniae was detected using broth microdilution method to evaluate minimum inhibitory concentration (MIC). In vivo safety and immunomodulatory effects were assessed in mice.

Results: Saponin exhibited an IC₅₀ of 20.16 ± 0.21 μg/mL in the DPPH assay. Inhibition zones against S. pneumoniae were observed at concentrations of 10 μg/mL (6.4 mm), 20 μg/mL (17.6 mm), and 50 μg/mL (21.9 mm). In vivo, treatment with 20 μg/mL saponin resulted in a 0.06 μg/mL fold increase in IFN-γ levels compared to control without adverse effects on hepatic enzymes, hematological parameters, or histopathology.

Conclusions: Saponin from G. glabra demonstrates promising in vitro antioxidant and antibacterial activities against S. pneumoniae, with favorable safety and immunomodulatory profiles in vivo, supporting its potential as a natural therapeutic candidate.