<p class="MDPI12titleori1" style="mso-line-height-alt: 14.0pt;"><span style="mso-bidi-font-size: 18.0pt; mso-ligatures: standardcontextual;">Anti-Inflammatory Effects of RFIP1, a Novel Serine Protease Inhibitor from <em>Rhamnus frangula</em>, in a Xylene-Induced Mouse Ear Inflammation Model

Inflammation is commonly treated using non-steroidal anti-inflammatory drugs, analgesics, corticosteroids, and immunosuppressive agents. This study evaluated the anti-inflammatory activity of a novel serine protease inhibitor, RFIP1, isolated from Rhamnus frangula, using a xylene-induced ear inflammation model in male BALB/c albino mice. Fifty mice were randomly divided into five groups: Group A (control), Group B (xylene-induced inflammation treated with saline, 0.1 mL), Group C treated with dexamethasone (1.25 mg/kg body weight), Group D treated with RFIP1 (2.4 mg/kg body weight), and Group E treated with RFIP1 (4.8 mg/kg body weight). All treatments were administered intravenously via the tail vein for six consecutive days. Xylene induction caused a significant increase in neutrophil serine protease (NSP) expression and elevated serum levels of the pro-inflammatory mediators interleukin-1β, interleukin-6, tumor necrosis factor-α, and nitric oxide. Treatment with Dexamethasone and low-dose RFIP1 significantly reduced NSP expression and cytokine levels. Notably, administration of RFIP1 at 4.8 mg/kg produced a significant dose-dependent reductionr in NSP expression and inflammatory mediators compared with both Dexamethasone and the lower RFIP1 dose. These findings suggest that RFIP1 possesses potent anti-inflammatory activity and may represent a promising therapeutic candidate for inflammatory conditions.