Valorization of lavender (Lavandula angustifolia Mill) distillation residues: An integrated approach of antioxidant-guided extraction, chemical profiling, and multiple bio-functional evaluation

Lavandula angustifolia is a key essential oil crop in China, with over 95 % of its cultivation concentrated in the Ili River Valley. The steam distillation process for essential oil generates substantial residues that are currently underexploited. This study establishes a pioneering, antioxidant-guided biorefinery approach for extraction and purification of bioactive substance from these lavender residues. Optimal ethanol-water extraction (50 % v/v, solid-liquid ratio 1:70, 2.5 h, two cycles) yielded a crude lavender residue extract (Lre), which was subsequently purified using AB-8 macroporous resin (loading concentration: 9 mg/mL, eluted with 60 % ethanol at 2 mL/min) to obtain a lavender residue purified extract (LRPE). Compared to Lre, LRPE exhibited 2.1-fold greater DPPH radical scavenging capacity (IC50 = 0.1813 ± 0.016 mg/mL) and 1.8-fold stronger ABTS radical inhibition (IC50 = 0.1683 ± 0.011 mg/mL), alongside potent tyrosinase inhibitory activity (IC₅₀ = 1.5989 ± 0.038 mg/mL), an indicative of significantly enhanced bioactivity. UHPLC-Q-Orbitrap-HRMS analysis of LRPE identified 42 phytochemicals, predominantly phenolic acids (19 compounds) and flavonoids (11 compounds), providing a chemical basis for the observed effects. In vitro assays demonstrated LRPE’s triple functional efficacy: mitigated H2O2-induced oxidative stress in HepG2 cells by reducing malondialdehyde levels and enhancing superoxide dismutase activity; suppressed LPS-induced inflammation in RAW264.7 macrophages by inhibiting nitric oxide overproduction and the secretion of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β); and dose-dependently inhibited melanogenesis in α-MSH-stimulated B16F10 cells (25–100 μg/mL). In vivo validation in zebrafish confirmed that LRPE concentration-dependently reduced endogenous body pigmentation, melanin content, and tyrosinase activity. In sum, this work transformed distillation waste into valuable multifunctional ingredients and provided a scientific and technical basis for advancing the lavender essential oil industry.