Secondary compounds characterization in some autochtonous species from a North-Eastern region of Tunisia

Several native species were collected in the region of Zaghouan (eastern-north of Tunisia, semi-arid) in order to evaluate their chemical diversity for an eventual animal use context, during the period of spring 2011. Some secondary compounds were determined by colorimetric quantification in leaves and twigs. Essential oils from these species were extracted by hydro-distillation and then analyzed using gas chromatography technique, coupled with mass spectrometry (GC per MS). Results showed that among the studied species, Myrtus communis presented the highest total polyphenol (101.3 mg GAE per g DM), while Artemisia herba-alba and Ruta Chalepensis were the lowest ones (13.2 and 13.7 mg GAE per g DM respectively). Condensed tannin content in Juniperus phoenicea (43.8 mg CE per g DM) was largely higher than in all the other species, in which it ranged approximately between 1 and 5 mg per g DM. In addition, saponin content was the utmost in J. phoenicea (25.2 mg per g DM) as compared to the others species, where it varied between almost 6 and 13 mg per g DM. The amount of flavonoids varied widely between 28.6 and 5.1 mg per g DM in Mentha pelagium and M. communis respectively. Essential oils of all species were composed of wide pools of identified components. For instance, the main compounds were 1.8-cineol in Rosmarinus officinalis (39 per cent), thymol (61.3 per cent) in Thymus vulgaris, and carvacrol (64.8 per cent) in A. herba-alba. It was concluded that the vegetal diversity in the studied area presented a consequent chemical diversity, available for animals as fed in grazing or in housing conditions. These bioactive molecules, mainly essential oils, may be used for their antimicrobial actions to improve animal health and performance. In this connection, in vitro studies are currently carried out in our