Vol. 7, Issue 2, Part G (2025)

Background: Ectopic endometrial tissue, inflammation, oxidative stress, angiogenesis, and pain are the hallmarks of endometriosis, a chronic, estrogen-dependent illness. The need for new adjunctive medications is highlighted by the fact that traditional treatments, such as hormone suppression and surgery, are frequently ineffective or poorly tolerated. The anti-inflammatory, antioxidant, antispasmodic, and phytoestrogenic qualities of fennel (Foeniculum vulgare) and its main phenylpropene component, anethole, may target important endometriosis triggers.

Methods: With a focus on molecular pathways pertinent to endometriosis, we conducted a thorough literature analysis of in vitro, in vivo, and clinical research investigating fennel extracts or pure anethole. PubMed, Scopus, and ScienceDirect were among the databases that were examined; they included foundational work and research conducted during the last ten years.

Findings: Immunomodulatory and anti-inflammatory effects: In preclinical models, anethole increases IL-10, decreases pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6), inhibits NF-κB activation, and suppresses COX-2-mediated prostaglandin formation.

Antioxidant activity: Anethole and fennel extracts increase endogenous antioxidant enzymes (SOD, CAT, GPx), reduce lipid peroxidation (MDA), and reduce the production of reactive oxygen species.

Anti-invasive and anti-angiogenic properties: Anethole inhibits the expression of MMP-2/9 and VEGF/VEGFR-2 signalling, which may hinder lesion invasion and neovascularization.

Hormonal modulation: Although its overall impact on endometriosis is yet unknown, anethole, a weak phytoestrogen, relaxes the smooth muscles of the uterus and may affect the balance of estrogen and progesterone.

Clinical data: Research on primary dysmenorrhea shows that fennel oil, which is high in anethole, offers analgesia on par with NSAIDs. However, there are currently no clinical research evaluating the effects of fennel or anethole on endometriosis.

Conclusion and Prospects for the Future: Fennel and anethole are multi-targeted modulators of pathways related to endometriosis, according to preclinical research. However, there are still important limitations in pharmacokinetic characterisation, direct assessment in endometriosis models, and standardized formulations. To determine safety, ideal dosage, and therapeutic effectiveness in endometriosis-affected women, well-planned, placebo-controlled clinical studies utilizing pure anethole or defined fennel extracts are required.