Citral, a major component of lemon myrtle (Backhousia citriodora) essential oil, inhibits adipogenesis in 3T3-L1 preadipocytes during mitotic clonal expansion

Lemon myrtle essential oil (LMEO), a popular food-flavoring and perfume, has anti-inflammatory and antioxidant properties, and contains citral in abundance. Citral-enriched essential oils exhibit anti-obesity effects; however, the effect of LMEO on adipogenesis and the precise mechanism of citral have not been elucidated. This study evaluated the anti-adipogenic activity of commercial LMEO and its components, geranial, neral and citral (a mixture of geranial and neral), in 3T3-L1 cell differentiation and identified the anti-adipogenic mechanism of citral. Treatment of 3T3-L1 preadipocytes with various concentrations of LMEO, neral, geranial, and citral for 24 h and 48 h showed that LMEO (12.5–25 μg/mL) inhibited 3-isobutyl-1-methylxanthine, dexamethasone, and insulin (MDI)-induced differentiation of preadipocytes. Citral, accounting for 88.67% of total compounds in LMEO, also suppressed MDI-induced differentiation and expression of adipogenic transcription factors (PPARγ, C/EBPα, and Fabp4). Additionally, citral inhibited the early stages of differentiation, particularly mitotic clonal expansion (MCE), by deactivating cell cycle-related factors (cyclins and cyclin-dependent kinases) and arresting the cell cycle at G₀/G₁ phase, which was caused by inhibiting upstream signaling pathways, especially PI3K/AKT pathway. Therefore, regulation of early stages of adipogenesis, especially MCE, is a key mechanism underlying the anti-adipogenic activity of citral. LMEO and citral can be potentially used as anti-obesity agents.