Glycyrrhizic acid nanoparticles inhibit LPS-induced inflammatory mediators in 264.7 mouse macrophages compared with unprocessed glycyrrhizic acid

Abstract

Glycyrrhizic acid (GA), the main component of radix glycyrrhizae, has a variety of pharmacological activities. In the present study, suspensions of GA nanoparticles with the average particle size about 200 nm were prepared by a supercritical antisolvent (SAS) process. Comparative studies were undertaken using lipopolysaccardide (LPS)-stimulated mouse macrophages RAW 264.7 as in vitro inflammatory model. Several important inflammation mediators such as NO, PGE2, TNF-α and IL-6 were examined. These markers were highly stimulated by LPS and were inhibited both by nano-GA and unprocessed GA in a dose-dependent manner, especially PGE2 and TNF-α. However nano-GA and unprocessed GA inhibited NO only at a high concentration. In general, we found that GA nanoparticle suspensions exhibited much better anti-inflammatory activities compared to unprocessed GA.

Keywords: glycyrrhizic acid; inflammatory cytokines; mouse macrophages RAW 264.7; nanoparticle.

Figure 1

Scanning electron microscopy result of (A) unprocessed GA and (B) GA nanoparticles. Abbreviation: GA, glycyrrhizic acid.

Figure 2

Effect of different concentrations of GA nanoparticles and unprocessed GA on LPS-induced nitric oxide. Note: *P < 0.05, significantly different from the LPS-treated group by unpaired Student’s t-test. Abbreviations: GA, glycyrrhizic acid; LPS, lipopolysaccharide.

Figure 3

Effect of different concentrations of GA nanoparticles and unprocessed GA on LPS-induced PGE₂. Notes: *P < 0.05; **P < 0.01, significantly different from the LPS-treated group by unpaired Student’s t-test. Abbreviations: GA, glycyrrhizic acid; LPS, lipopolysaccharide; PGE₂, prostaglandin E₂.

Figure 4

Effect of different concentrations of GA nanoparticles and unprocessed GA on LPS-induced TNF-α. Notes: *P < 0.05; **P < 0.01, significantly different from the LPS-treated group by unpaired Student’s t-test. Abbreviations: GA, glycyrrhizic acid; LPS, lipopolysaccharide; TNF-α, tumor necrosis factor-α.

Figure 5

Effect of different concentrations of GA nanoparticles and unprocessed GA on LPS-induced IL-6. Note: **P < 0.01, significantly different from the LPS-treated group by unpaired Student’s t-test. Abbreviations: GA, glycyrrhizic acid; LPS, lipopolysaccharide;IL-6, interleukin-6.