Effects of extraction methods and solvent polarity on bioactivity potential of Citrus aurantifolia (key lime) peel extracts

This study compared cold maceration and Soxhlet extraction of Citrus aurantifolia (lime) peels using six solvents of different polarity (n-hexane, chloroform, ethyl acetate, acetone, methanol, and water) to assess phytochemical content, antioxidant capacity, and antimicrobial activity. Extraction yields ranged from 1.7% to 52.4%, with the highest yield obtained from Soxhlet aqueous extraction (52.4%). Total phenolic and flavonoid contents were highest in Soxhlet methanolic extracts (98.6 mg GAE g⁻¹ and 70.05 mg QE g⁻¹, respectively), corresponding to strong antioxidant activity (DPPH IC₅₀ = 7.75 µg mL⁻¹). Soxhlet extracts also showed superior antimicrobial efficacy against multidrug-resistant bacteria, with ethyl acetate and methanolic extracts exhibiting MIC values as low as 0.39 and 0.78 µg mL⁻¹, respectively. In conclusion, the valorization of lime peel waste into bioactive-rich extracts may support both therapeutic applications and sustainable circular bioeconomy strategies.