Ethanol Extract of Sargassum siliquastrum Inhibits Lipopolysaccharide-Induced Nitric Oxide Generation by Downregulating the Nuclear Factor-Kappa B Signaling Pathway

Figure 5

SS extract enhances LPS-induced activation of the Nrf2/HO-1 pathway. (a) Western blot analysis of the total and phosphorylated forms of Akt and HO-1 in cells treated for 20 h with the SS extract in the absence or presence of LPS stimulation (1 μg/mL). Densitometric analysis was performed using ImageJ software. (b) Real-time PCR analysis to determine changes in mRNA levels of Hmox1 following treatment with the SS extract (SS) in LPS-stimulated RAW 264.7 cells. (c) A reporter gene assay showing regulation of Nrf2 transcriptional activity by the SS extract in RAW 264.7 cells stimulated with LPS (1 μg/mL) in the presence or absence of the SS extract for 6 h (d) Determination of changes in cellular ROS levels after 20 hours of LPS (1 μg/mL) stimulation in the absence or presence of the SS extract. (e) Schematic diagram for the mechanism underlying the anti-inflammatory effect of the SS extract through inhibition of the NF-κB pathway activation and enhancement of the LPS-induced Nrf2/HO-1 pathway. The bars represent the mean ± standard deviation (SD); ^∗: , ^∗∗: , and ^∗∗∗: compared with the indicated group. SS, Sargassum siliquastrum; LPS, lipopolysaccharide.

(a)

(b)

(c)

(d)

(e)