IMPACT OF ENVIRONMENTAL ARIDITY ON THE PHYTOCHEMICAL COMPOSITION OF PHENOLIC EXTRACTS AND ESSENTIAL OIL FROM Vitex agnus-castus L. LEAVES ACCLIMATED IN THE ALGERIAN SAHARA.

Vitex agnus-castus L. (Lamiaceae) is a bushy shrub native to Asian and Mediterranean regions and is often used in traditional and popular medicine for its many biological properties and aromatic virtues. There are many studies devoted to the phytochemistry of species growing in endemic conditions, but little or no information is available on species growing in a subtropical desert climate. In this perspective, a comparative study with works carried out almost everywhere in the world, aims to analyze phenolic extracts and essential oil of leaves harvested in arid regions of the south-west of the Algerian Sahara. The phenolic extracts are characterized by a high content of anthocyanidins (6.1±0.07 mg·g-1 DM) and by the presence of 40 components detected by HPLC-DAD, among which five phenolic acids, two flavones and two flavonols are identified. The essential oil is characterized by chemical diversity of volatile substances, 68 (98.97%) are selected by GC-MS of which 52 (89.72%) are identified. Hydrocarbon compounds (25.03%) are less abundant than their oxygenated (64.69%). These were distributed as follows: 25 monoterpenes (32.12%), 3 sesquiterpenes (31.84%), 1 diterpene (0.16%), 2 norisoprenoids (0.29%) and a non-terpene oxygenated compound (0.28%). A unique compound characterizes the oxygenated sesquiterpenes, caryophyllene oxide, which represents one-third (31.5%) of the total area of the foliar essential oil; this molecule is absent or very rare in all the other essential oils indicated in literature. Considering these results, V. agnus-castus acclimatized in the arid Saharan zone, presents a particular chemotype compared to those of endemic populations. [ABSTRACT FROM AUTHOR]