Inflammatory reactions play an important role in maintaining health as the body's defense mechanism that recognizes and eliminates external stimuli (Pahwa et al., 2021). However, persistent and uncontrolled inflammation leads to major chronic diseases such as cancer, cardiovascular disease, diabetes, rheumatoid arthritis, and inflammatory bowel disease (IBD). Macrophages are specialized phagocytes containing mononuclear and dendritic cells and are the main cell members that modulate innate immunity (Parisi et al., 2018). The macrophages play a major role in antigen presentation, cytokine production, phagocytosis, and immunomodulation (Germic et al., 2019). Macrophages recognize stimulation through receptors such as TLR, and activate mitogen-activated protein kinases (MAPK), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), AKT signaling pathway to produce nitric oxide (NO) and pro-inflammatory cytokines (Harikrishnan et al., 2018). NO is increased by iNOS and causes rheumatoid arthritis and tissue damage. IL-6, TNF-α, and IL-1β are representative infectious cytokines that are increased in inflammatory conditions (Kany et al., 2019). Prostaglandin E2 (PGE2), converted by cyclooxygenase (COX), acts as an inflammatory mediator that promotes the activation of neutrophils, macrophages, and obese cells in the early stages of inflammation, such as IL-6 and IL-1 (Tsuge et al., 2019). Heme oxygenase-1 (HO-1) is activated by the nuclear factor erythroid 2-related factor 2 (Nrf2) and has been reported to inhibit inflammation in stimulated (Paine et al., 2010).

The control over inflammatory factors and mechanisms of action described above has been studied as an important key in the management of inflammatory diseases (Lee et al., 2009; Tewtrakul et al., 2011; Bognar et al., 2013). As a result, various drugs such as aspirin, naproxen, and brufen were developed (Duggan et al., 2010). However, with reports on the side effects such as hepatotoxicity, headache, gastrointestinal disorders, and hypersensitivity reactions (Rainsford, 2013), research on inflammatory regulators using natural materials is constantly increasing (Muluye et al., 2014, Ghasemian et al., 2016; Yatoo et al., 2018).

Peucedanum japonicum Thunberg is a perennial herbaceous plant of the genus Peucedanum in the Apiaceae family and is an edible plant native to China, Korea, Japan, and the Philippines. It is commonly consumed as a vegetable and is known to be used as an herbal medicine (Hwang et al. 2022). P. japonicum has been used in traditional medicine to soothe coughs and colds, and to treat many other inflammatory diseases. And in Donguibogam, it is mentioned that it is effective for pulse, dizziness, and gout (Kim et al. 2013). In addition, P. japonicum has been reported to exhibit antioxidant and anti-obesity effects and treat headaches, as well as studies on influenza virus replication inhibition (Nukitrangsan et al., 2012; Kanazawa et al. 2022). However, only the root part of the plant has been mainly studied (Chun et al., 2018), and studies evaluating the anti-inflammatory effect of the leaves are insufficient. In particular, utilizing absolute ethanol for extraction has been shown to enhance extraction efficiency, resulting in higher yields of plant compounds as compared to lower concentrations of ethanol or alternative solvents. Furthermore, some plant compounds are susceptible to degradation in aqueous or hydroalcoholic solvents, which can adversely impact the stability and potency of the final extract (de Santana et al., 2017). Therefore, in this study, P. japonicum leaves were extracted using ethanol from rodent-derived macrophages stimulated with LPS and the anti-inflammatory efficacy was evaluated.