Essential Oils of Foeniculum vulgare subsp. piperitum and Their in Vitro Anti-Arthritic Potential

Wild Foeniculum vulgare subsp. piperitum (C.Presl) Bég. flowers, fruits and leaves were extracted with steam distillation and obtained essential oils (EOs) were characterized using GC/MS. The study was designed to verify the potential effectiveness of fennel EOs in the treatment of inflammation and arthritis. Since tissue proteins denaturation is a major cause of arthritic diseases, fennel EOs and their main constituents were evaluated for their ability to inhibit the heat-induced proteins degradation using bovine serum albumin as a protein model. Moreover, the in vitro inhibitory effects of the three EOs on the pro-inflammatory mediator nitric oxide (NO) production were verified in LPS-stimulated RAW 264.7 cells. Estragole (28.81-33.40 %), anethole (24.16-27.40 %), fenchone (9.76-18.48 %), α-phellandrene (1.63-8.37 %) and limonene (5.54-6.05 %) were the major constituents. All the EOs showed a concentration-dependent biological activity, being the flower EO the most effective in inhibiting NO production (IC₅₀ =232.2±11.3 μg/mL). The leaf EO showed a very good bovine serum albumin (BSA) anti-denaturation activity (IC₅₀ =95.9±2.4 μg/mL). Moreover, four components were proved to be effective in protecting protein from heat-induced degradation, being α-phellandrene the most active compound (IC₅₀ =73.2±1.9 μg/mL).