Phytochemical composition and antioxidant activity of medicinal plants collected from the Tunisian flora.

Polyphenols, flavonoids and condensed tannins contents, as well as the antioxidant activity of the ethanolic and aqueous extracts obtained from aerial parts of 10 wild Tunisian plants, have been determined. Extracts showed appreciable levels of polyphenols and flavonoids, which reached 215.16 mg GAE g-1 DW in Lavandula stoechas ethanolic extract, and 49.12 mg RE g-1 DW in Thapsia garganica aqueous extract. The majority of tested extracts exhibited low total condensed tannins content, except for Rhus tripartitum and Periploca laevigata. The antioxidant activity tests showed great activity, especially for R. tripartitum and Lavandula multifida (IC50 = 5.16 and 5.1 µg mL-1, respectively). Canonical Correspondence Analysis revealed clear groupings of species according to the solvent used.

Chemical composition and antioxidant activities of essential oils and methanol extracts of three wild Lavandula L. species.

A comparative study of essential oil composition, polyphenol content and antioxidant activities of Lavandula coronopifolia, Lavandula multifida and Lavandula stoechas subsp. stoechas were reported. Qualitative and quantitative variations in the composition of oils according to species were shown. Lavandula coronopifolia's oil was characterised by high proportions of trans-ß-ocimene (26.9%), carvacrol (18.5%), ß-bisabolene (13.1%) and myrcene (7.5%). The main components of L. multifida oil are carvacrol (65.1%) and ß-bisabolene (24.7%). Lavandula stoechas oil is rich in fenchone (34.3%) and comphor (27.4%). The total phenolic and flavonoid contents also significantly varied among species. Lavandula coronopifolia exhibits the highest phenolic and flavonoid contents (31.3 mg GAE g(-1) and 16.3 mg RE g(-1), respectively), followed by L. multifida (30.8 mg GAE g(-1) and 12.3 mg RE g(-1)). Methanolic extracts and essential oils displayed significant antioxidant activities. The level of antioxidant capacity varied according to extracts and species.