Antioxidant Activity and Total Phenolic and Flavonoid Contents of 30 Medicinal and Aromatic Plants Located in the South of Morocco

Ridouane El Guiche, Saida Tahrouch, Oukacha Amri, Khadija El Mehrach, Abdelhakim Hatimie

In this study, antioxidant activity, total phenolic and total flavonoid contents of 30 species extracts, from 15 botanical families grown on three localities (Agdz, Tafraout and Taroudannt) of Souss Massa Draa (Southern Morocco), were determined using spectrophotometric methods. DPPH radical cation assay was used for evaluation of free radical scavenging properties of investigated species. The results showed a remarkable high antioxidant activity in the majority of tested plants, especially in Tetraclinis articulata, Thymus leptobotrys, and Lavandula stoechas, which neutralized up to 90 % of DPPH radicals. However, Conyza canadensis showed the lowest antioxidant value (88.19%). The total phenolics content measured by Folin-Ciocalteu method, ranged from 2.54 to 55.62 µg of gallic acid equivalents (GAE)/mg of dry matter (DM). Ceratonia siliqua (55.63 µg GAE /mg), Cistus villosus (41.10 µg GAE /mg), Limoniastrum feei (36.52 µg GAE /mg) and Rubus ulmifolius (35.02 µg GAE /mg) had very high levels of phenolics, whereas in Conyza canadensis (2.54 µg GAE /mg) phenolics were quit low. For total flavonoids content, two methods were used. Spectrophotmoetric method using NEU reagent showed a significant levels of flavonoids in Inula viscosa (70.08 µg/mg), Globularia alypum (66.28 µg/mg), Teucrium chamaedrys (63.95 µg/mg), Ruta montana (59.9 µg/mg) and Ononis natrix (55.49 µg/mg). For the second method with aluminium trichloride (AlCl3), the amounts of total flavonoid expressed as rutin equivalents/g DM, were higher in Rubus ulmifolius (117.79 µg/mg), Ononis natrix (80.84 µg/mg), Rhus pentaphulla (67.67 µg/mg), Thymus leptobotrys (53.17 µg/mg) and Thymus satureioides (52.34 µg/mg). According to this method Mentha pulegium exhibited the lowest flavonoids concentration (9.46 µg/mg), while the first method revealed low levels of flavonoids content in Conyza canadensis (5.41 µg/mg).