Anti-inflammatory and analgesic activities of fingered citron (Citrus medica var. Sarcodactylus) fruit essential oil and its multi-target mechanism of action based on network pharmacology.

Abstract

OBJECTIVE: To investigate the chemical composition, anti-inflammatory and analgesic activities, and molecular mechanism of essential oil from Citrus medica var. Sarcodactylus (Fingered Citron) fruit, providing experimental basis for its development as a plant-derived anti-inflammatory and analgesic drug. METHODS: The essential oil components were analyzed by steam distillation (SD) combined with gas chromatography-mass spectrometry (GC-MS). In vitro antioxidant activity was evaluated using FRAP, ABTS, and DPPH assays. Anti-inflammatory activity was detected using LPS-induced RAW264.7 cell model. A rat osteoarthritis (OA) model was established to verify in vivo analgesic effects through behavioral assessment, inflammatory factor detection, and histopathological analysis. Network pharmacology and molecular docking were used to screen core targets and pathways. RESULTS: The essential oil mainly contained monoterpenes (d-limonene, &#x3b3;-terpinene) and sesquiterpenes (&#x3b2;-bisabolene), accounting for over 50% of the total components. In vitro experiments showed strong antioxidant activity (FRAP: 2300&#xa0;&#xb1;&#xa0;150&#xa0;&#x3bc;mol Fe/g, ABTS: 13.36&#xa0;&#xb1;&#xa0;0.22&#xa0;&#x3bc;mol TE/g) and anti-inflammatory activity (NO release IC&#x2085;&#x2080;&#xa0;=&#xa0;384.04&#xa0;&#x3bc;g/mL). In vivo experiments demonstrated that topical application significantly improved joint function in OA rats (grip strength restored to normal levels, reduced Lequesne MG score, P&#xa0;<&#xa0;0.01), downregulated inflammatory factors (TNF-&#x3b1;, IL-1&#x3b2;), and delayed cartilage degeneration. Network pharmacology identified core targets such as PTGS2, NOS2, and CALM1, with molecular docking showing that sitosterol &#x3b1;1 binds to CALM1 with a binding energy of -4.2&#xa0;kcal/mol. CONCLUSION: The essential oil exerts anti-inflammatory and analgesic effects, with a mechanism of action suggestive of a "multi-component, multi-target, multi-pathway" mode. Its active components may alleviate OA symptoms by inhibiting inflammatory signaling pathways (e.g., NF-&#x3ba;B), with potential involvement of calcium signaling regulation as suggested by molecular docking predictions. This study provides an experimental basis for developing novel topical anti-inflammatory and analgesic drugs.