Anti-Inflammatory and Anti-Superbacterial Properties of Sulforaphane from Shepherd's Purse

Abstract

Shepherd's purse, Capsella bursa-pastoris (L.) Medik., has been considered a health food for centuries in Asia and is known to contain the isothiocyanate compound sulforaphane. In this study, we evaluated the anti-inflammatory and antibacterial properties of a sulforaphane-containing solution (SCS) isolated from shepherd's purse. SCS had significant anti-inflammatory activity indicated by the decreased levels of nitric oxide (NO), cytokines (interleukin 1β [IL-1β], IL-6, and IL-10), and prostaglandin E2 (PGE2) in lipopolysaccharide-stimulated RAW 264.7 murine macrophages. In addition, SCS decreased the inducible NO synthase (iNOS) and cyclooxygenase 2 (COX-2) levels, which confirmed the anti-inflammatory activity of SCS. Further, SCS inhibited vancomycin-resistant enterococci (VRE) and Bacillus anthracis. The minimal inhibitory concentration was 250 µg/ml for VRE and 1,000 µg/ml for B. anthracis. Taken together, these data indicate that SCS has potential anti-inflammatory and anti-superbacterial properties, and thus it can be used as a functional food or pharmaceutical.

Keywords: Anti-inflammatory effect; Antimicrobial activity; Cytokine; RAW 264.7 murine macrophages; Shepherd's purse; Sulforaphane.

Fig. 1

The cell cytotoxicity of RAW 264.7 cells treated with different concentrations of sulforaphane-containing solution (SCS). Cells were treated with 0, 1, 5, 10, 50, 100, or 500 µg/ml SCS in the presence of 0.1 µg/ml lipopolysaccharide (LPS) for 24 h. The normal group was treated with media only. Results are expressed as mean±standard error (SE) from 3 independent experiments. ^*p<0.01 indicates significant differences from the LPS treated cells.

Fig. 2

Suppression of lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E₂ (PGE₂) production in RAW 264.7 cells using sulforaphane-containing solution (SCS). Cells were treated with 0, 1, 5, 10, 50, 100, or 500 µg/ml SCS in the presence of 0.1 µg/ml LPS for 18 h. The normal group was treated with media only. Results are expressed as mean±standard error (SE) from 3 independent experiments. ^*p<0.01 indicates significant differences from the LPS treated cells.

Fig. 3

Suppression of lipopolysaccharide (LPS)-induced cytokine production (interleukin 1β [IL-1β], IL-6, and IL-10 in RAW 264.7 cells using sulforaphane-containing solution (SCS). RAW 264.7 cells were treated with 0, 1, 5, 10, 50, 100, or 500 µg/ml SCS in the presence of 0.1 LPS for 18 h. The normal group was treated with media only. Results are expressed as mean±standard error (SE) from 3 independent experiments. ^*p<0.01 indicates significant differences from the LPS treated cells.

Fig. 4

Effects of sulforaphane-containing solution (SCS) on lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) protein expression. Inhibitory effect of SCS on LPS-induced iNOS and COX-2 protein expression in RAW 264.7 cells. Cells were treated with 0, 1, 5, 10, 50, 100, or 500 µg/ml SCS for 24 h. Cell lysates were electrophoretically separated and transferred, and expression levels of iNOS and COX-2 were detected with specific antibodies. β-actin was used as an internal control for western blot analysis.

Fig. 5

Effects of sulforaphane-containing solution (SCS) on inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) mRNA levels in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Cells were treated with LPS or LPS with SCS at concentrations indicated in Fig. 5. After 24 h of incubation, total RNA was subjected to qRT-PCR. The RT products were labeled with SYBR Green dye. Relative iNOS and COX-2 mRNA expression (2^-ΔΔCt) was determined by real-time PCR and calculated by Ct values for iNOS and COX-2 from β-actin mRNA. ΔΔCt=(Ct_{target gene}-Ct_β-actin)-(Ct_control-Ct_β-actin). Each value represents mean±SE of 3 independent experiments. ^*p<0.01 indicates significant differences from the LPS treated cells.