Evaluation of antioxidant and anti-inflammatory activity and identification of bioactive compound from the marine diatom, Odontella aurita extract

Abstract

Increased production of reactive oxygen species (ROS) leads to oxidative stress, with its damaging effect extending to the mitochondria and plasma membrane. Further, prolonged inflammation can result in chronic disease development. The marine microdiatom Odontella aurita is recognized for its potential in food and pharmaceutical development. Moreover, it contains antioxidant and anti-inflammatory properties. However, studies regarding the efficacy of their varying extract forms and their underlying mechanisms remain scarce. Therefore, this study aims to explore the antioxidant and anti-inflammatory effects of Odontella aurita extracts obtained using various extraction methods (hot water, 70% ethanol, and chloroform:methanol (CM)). Among the three Odontella aurita extracts, the CM extract demonstrated superior efficacy in protecting RAW 264.7 cells from H2O2-induced cytotoxicity. It significantly lowered the levels of ROS and enhanced the expression of superoxide dismutase and glutathione peroxidase. Furthermore, the CM extract outperformed other extracts in inhibiting LPS-induced nitric oxide production, reducing mRNA levels in nitric oxide synthase, cyclooxygenase, and the proinflammatory cytokines interleukin IL-1β, IL-6, TNFα. Additionally, CM extract effectively suppressed the activation of NF-κB/IκBα and JAK2-STAT3 in LPS-induced RAW 264.7 cells. HPLC–UV analysis revealed a remarkable 33-fold higher fucoxanthin content in CM compared to the ethanol extract. GC–MS analysis identified elevated levels of cholest-5-en-3-ol, phytol, eicosapentaenoic acid methyl ester, methyl palmitate, palmitoleic acid methyl ester, and neophytadiene in the CM extract. These findings suggest that Odontella aurita CM extract is a promising antioxidant candidate for preventing or treating inflammatory diseases, consequently emphasizing its potential for further development. Graphical Abstract