The objective of this work was to evaluate the antioxidant properties of Lavandula latifolia
waste obtained after essential oil distillation. Samples of 12 wild populations of the Lavandula
genus collected between 2009 and 2010 were hydrodistilled and their by-products
were analyzed using the FolineCiocalteu, free radical scavenging activity (2,2-diphenyl-1-
picrylhydrazyl), and the ferric reducing antioxidant power (FRAP) methods. Rosmarinic
acid, apigenin, and luteolin contents were analyzed by high-performance liquid chromatographyediode
array detection. The mean of total phenolic content ranged from
1.89 ± 0.09 mg gallic acid equivalents/g dry weight to 3.54 ± 0.22 mg gallic acid equivalents/
g dry weight. The average value of the half maximal effective concentration (EC50) for
scavenging activity ranged from 5.09 ± 0.17 mg/mL to 14.30 ± 1.90 mg/mL and the variability
of the EC50 in FRAP ranged from 3.72 ± 0.12 mg/mL to 18.55 ± 0.77 mg/mL. Annual
variation was found among these species and the environmental conditions of 2009 were
found to be more favorable. The plants collected from Sedano showed the highest antioxidant
power. Our results show that rosmarinic acid and apigenin in these species
contributed to the antioxidant properties of the waste. In conclusion, the by-product of the
distillation industry could be valorizing as a source of natural antioxidants.