Ammoides pusilla (Brot.) Breistr. from Algeria: Effect of harvesting place and plant part (leaves and flowers) on the essential oils chemical composition and antioxidant activity

The chemical variability and antioxidant activity of the flower and leaf essential oils (EOs) of Ammoides pusilla, collected at Algeria was evaluated. The EOs were isolated by hydrodistillation and analyzed by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS). Antioxidant activity was assessed by DPPH, ABTS, Reducing Power and TBARS assays. Oxygen-containing monoterpenes (54-77%) dominated all but one A. pusilla leaf EOs, and in two flower EOs (53% both). Thymol dominated in practically all leaf and flowers EOs, but cumin alcohol, p-cymene and limonene attained also relatively high percentages in some EOs. A strong negative correlation (p50 values of ABTS, DPPH, and hydroxyl scavenging activity and the percentages of p-cymene and cumin alcohol present in EOs were observed, showing that higher levels of these monoterpenes were responsible for the best activities found. In spite of this finding, the antagonism and/or synergism between EO components must be taken into account, since the EO activity can only be considered as a whole. Moreover, given the EOs chemical variability their use as antioxidants, should be preceded by their chemical evaluation.