김당단백질의 TLR4 신호전달을 통한 염증반응 저해 효과

Abstract

Antioxidant activity has become a 'hot' topic and the subject of intensive investigations due to the ever increasing demand by the food and pharmaceutical industries to develop natural bioactive anti-aging and anti-carcinogenic compounds that demonstrate measurable health benefits.So many synthetic antioxidants were developed but have side effects such as liver damage and carcinogenesis. Due to concerns on the toxic of synthetic antioxidants, the search for alternatives from natural sources has received much interest. Over the last two decades, a wide range of phytochemicals from different kinds of terrestrial plant materials have already been evaluated. Recently, many researchers have studied on the algae as a source with potential biological activities, because many marine algae extracts have been demonstrated to have strong antioxidant properties. For example, there are studies in the literature on antioxidant activity associated to sulfated polysaccharides from seaweed. In case of phloroglucinol, the derivative from Conyza aegyptiaca, appeared protective effects on oxidative damage to cells through the increase of cellular catalase activity and the regulation of extracellular signal-related kinase signaling pathway. Also phloroglucinol showed to inhibit nitrite known as precursor to produce a carcinogenic N-nitroso compounds. Most of the study researched algae have investigated its polysaccharides, but its protein was rarely studied. Since the oxidative stress was known to be associated with the causes of chronic systemic inflammation, the antioxidants could help control this condition. In this study, we extracted a glycoprotein from Porphyra yezoensis (PGP), Which had an antioxidant effect, and examined the mechanism related with its effects. We confirmed that PGP treatment inhibited the ROS and NO production in LPS-treated RAW 264.7. The signaling pathway of toll-like receptor 4(TLR4), a critical sensor of lipopolysaccharide, was activated by LPS and increased the release of pro-inflammatory mediator and cytokines through a cascade of the kinases involving mitogen-activated protein kinase(MAPK) and transcription factor NF-κB. Otherwise, the co-treatment with PGP and LPS inhibited the LPS-induced TLR4 signaling pathway activation and the expression of TNF-α, IL-1β, iNOS and COX-2. Therefore, we suggested PGP could be used a potential antioxidant for anti-inflammation.