Antioxidant and antiproliferative activity of Laurus nobilis L. (Lauraceae) leaves and seeds essential oils against K562 human chronic myelogenous leukaemia cells.

The antioxidant and antiproliferative activities of the essential oils from Laurus nobilis leaves and seeds in relation to their composition were analysed. The most abundant components of the leaf essential oil were 1,8-cineole, 1-p-menthen-8-ethyl acetate, linalool and sabinene, while the seed oil was characterised by β-ocimene, 1,8-cineole, α-pinene and β-pinene as main constituents. Both seed and leaf essential oils exhibited a scavenging effect on the DPPH radical, with IC₅₀ values of 66.1 and 53.5 µg mL⁻¹, respectively. The leaf essential oil showed the strongest antioxidant activity in the β-carotene/linoleic acid system, with an IC₅₀ value of 35.6 µg mL⁻¹ after 30 min of incubation. Both leaf and seed oils inhibited proliferation of the K562 tumour cell line with IC₅₀ values of 95 and 75 µg mL⁻¹, respectively. The L. nobilis leaf oil showed a percentage of erythroide differentiation of 15% at a concentration of 10 µg mL⁻¹. A value of 12% was found for the seed essential oil at a concentration of 50 µg mL⁻¹. When the oils were added to a suboptimal concentration of the commercial drug, cytosine arabinoside, a clear synergic effect was observed.