Immunostimulatory Activity of Polysaccharides Extracted from Celosia cristata Flowers.

Macrophages play a major role in innate immune responses by producing a variety of immune mediators and cytokines. The stimulation of macrophages by natural products may lead to an enhanced innate immune system. This study evaluated the immunostimulatory effects of a polysaccharide-rich crude fraction of Celosia cristata L. flowers (CCP) on murine macrophages. CCP treatment induced the production of inducible nitric oxide synthase, cyclooxygenase-2, and cytokines by macrophages. Mechanistically, the activation of mitogen-activated protein kinases, NF-κB and toll-like receptor 4 were found to be associated with the stimulatory functions of CCP. CCP was found to be primarily composed of galacturonic acid and glucose in addition to small amounts of arabinose and galactose. This study demonstrated that CCP may enhance the innate immune responses and potentially improve the immune functions in the body.

Lindera glauca (Siebold et Zucc.) Blume Stem Extracts Protect Against tert-Butyl Hydroperoxide-Induced Oxidative Stress.

In this study, we investigated the antioxidant and protective effect of Lindera glauca stem (LGS) extracts against oxidative stress. We compared antioxidant properties of water extract (LGSW) with ethanol extract (LGSE) by determining the contents responsible for antioxidant activities such as polyphenols and flavonoids. Antioxidant properties were also determined by 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and ferric reducing antioxidant power (FRAP). Lipid peroxidation was estimated using ferric thiocyanate (FTC) and thiobarbituric acid (TBA) method. Both LGSW and LGSE strongly inhibited lipid peroxidation. Especially, LGSE showed a protective effect through increasing cell viability, decreasing intracellular reactive oxygen species (ROS) against tert-butyl hydroperoxide-induced oxidative stress in Chang cells. Furthermore, LGSE increased antioxidant related enzyme activities such as catalase, glutathione S-transferase, glutathione peroxidase, and superoxide dismutase gene expression against oxidative stress in a zebrafish model. Our findings suggest that LGSE could be useful for developing potential therapeutic agents with protective effects against oxidative stress.

Immune-Stimulatory Effects of Althaea rosea Flower Extracts through the MAPK Signaling Pathway in RAW264.7 Cells.

Althaea rosea (Linn.) is a medicinal plant from China and Korea that has been traditionally used to control inflammation, to stop bedwetting and as a mouthwash in cases of bleeding gums. Its flowers are employed medicinally for their emollient, demulcent and diuretic properties, which make them useful in chest complaints. Furthermore, a flower extract decoction is used to improve blood circulation, for the treatment of constipation, dysmenorrhoea, haemorrhages, etc. However, the possible mechanisms of the immune-stimulatory effect remains to be elucidated. Therefore, we investigated the role of Althaea rosea flower (ARF) extracts in the immune-stimulatory effect of macrophages and the underlying mechanisms of action. ARF water extract (ARFW) could dose-dependently increase NO production and cytokines (IL-6 and TNF-α). We also found that ARFW significantly increased the expression of iNOS and COX-2 proteins in RAW264.7 cells. Consistent with these results, MAPK protein (JNK, ERK, p38) expression levels were induced after treatment with ARFW. Additionally, ARFW showed a marked increase in the phosphorylation level of IκBα and subsequent IκBα degradation allowing NF-κB nuclear translocation. These results suggest that the immune-stimulatory effect of A. rosea flower extracts is mediated through the translocation of NF-κB p65 subunit into the nucleus from the cytoplasm and subsequent activation of pro-inflammatory cytokines (IL-6 and TNF-α) and other mediators (iNOS and COX-2), which occurs mainly through MAPK signalling pathway. Thus, we suggest that ARFW could be considered as a potential therapeutic agent useful in the development of immune-stimulatory compounds.