Phytochemical composition of the Algerian Laurus nobilis L. leaves extracts obtained by solvent-free microwave extraction and investigation of their antioxidant activity

This paper focuses the phytochemical composition of bay leaves essential oils obtained by solvent-free microwave extraction (SFME) and by the hydrodistillation (HD) for comparison. Essential oils had similar qualitative but different quantitative composition. For HD and SFME, the main constituents on the oils differed respectively in 1,8-cineole (26.4-30.9)%, sabinene (9-9.6)%, alpha-terpinyl acetate (9.5-7.8)%, linalool (4.9-9.5)%, alpha-terpineol (3.3-7.6)%, alpha-pinene (9.2-4.6)%, methyl eugenol (5-6.2)% and eugenol (1.2-3.6)%. The HD essential oil and SFME volatile extract inhibited nitric oxide production by stimulated mice peritoneal neutrophils (IC 50 : 6.65 and 13.75) mg/mL and dose dependently scavenged superoxide anion (IC 50 : 0.048 and 0.058) mg/mL. Inversely, these volatile extracts enhanced myeloperoxidase release (EC 50 : 0.72 and 0.29) mg/mL. Moreover, the potentiating effect of laurel extracts on exocytosis granules could collaborate in trapping and killing of extracellular pathogens by neutrophils extracellular traps (NETs).