Pinus thunbergii Parl. Extracts Reduce Acute Inflammation by Targeting Oxidative Stress

Abstract

Pinus thunbergii Parl. (PTP) has traditionally been used for edible and medicinal purposes to treat several disorders, including diabetes and neuralgia. Therefore, this study sought to evaluate the inhibitory effects of PTP leaf ethanol extracts on acute inflammation. Moreover, the reactive oxygen species (ROS) scavenging activity, superoxide dismutase (SOD) activity, lipopolysaccharide (LPS)-induced nitric oxide (NO) generation, and H2O2-induced lipid peroxidation capacity of PTP were assessed in vitro in RAW 264.7 macrophages. Our results suggest that PTP prevents cell damage caused by oxidative free radicals and downregulates the expression of LPS-induced inflammation-associated factors including inducible nitric oxidase synthetase (iNOS), cyclooxygenase-2 (COX-2), and prostaglandin E2 (PGE2). PTP inhibited NO production by 53.5% ( $P<0.05$ ) and iNOS expression by 71.5% ( $P<0.01$ ) at 100 µg/mL. PTP at 100 µg/mL also inhibited ROS generation by 58.2% ( $P<0.01$ ) and SOD activity by 29.3%, as well as COX-2 expression by 83.3% ( $P<0.01$ ) and PGE2 expression by 98.6% ( $P<0.01$ ). The anti-inflammatory effects of PTP were confirmed in vivo using an arachidonic acid (AA)-induced ear edema mouse model. Ear thickness and myeloperoxidase (MPO) activity were evaluated as indicators of inflammation. PTP inhibited edema formation by 64.5% ( $P<0.05$ ) at 1.0 mg/ear. A total of 16 metabolites were identified in PTP extracts and categorized into subgroups, including two phenolic acids (mainly quinic acid), seven flavonoids, five lignans, one sesquiterpenoid, and one long-chain fatty acid. Therefore, our results suggest that PTP possesses anti-inflammatory properties.