Author/Authors :
yahyaoui, m. université de carthage - institut préparatoire aux études scientifiques et techniques(ipest), faculté des sciences de bizerte - laboratoire matériaux, molécules et applications (lmma), La Marsa, Tunisia , ghazouani, n. université de carthage - institut préparatoire aux études scientifiques et techniques(ipest) - laboratoire matériaux, molécules et applications (lmma), La Marsa, Tunisia , saoudi, s. university of la laguna - university institute of tropical diseases and public health of the canary islands, San Cristóbal de La Laguna, Spain , saoudi, s. university of carthage - national institute of applied sciences and technology, insat - laboratoire d’ecologie et de technologie microbienne, Tunis, Tunisia , chammem, n. university of carthage - national institute of applied sciences and technology, insat - laboratoire d’ecologie et de technologie microbienne, Tunis, Tunisia , abderrabba, m. université de carthage - institut préparatoire aux études scientifiques et techniques(ipest) - laboratoire matériaux, molécules et applications (lmma), La Marsa, Tunisia
Abstract :
Thymelaea hirsuta L. is a medicinal plant known for its therapeutic virtues in traditional medicine. In this regard, the central composite design was implemented to improve the amounts of phenolic compounds extracted as well as the antioxidant compounds from T. hirsuta ’s aerial parts. Three parameters namely the extraction temperature (24-60°C), the time (2-18 h) and the solvent (0-100 % methanol/ethyl acetate proportion) were used as independent variables. The second-order polynomial equation was carried out at different levels and a total of 16 experiments with two replicates at the center were conducted in order to obtain the optimal extraction conditions. Total phenolics levels and a total of 16 experiments with two replicates at the center were conducted in order to obtain the optimal extraction conditions. Total phenolics (65.60±0.76 to 254.55±5.39 mg GAE/g dw), flavonoids content (61.59±1.34 to 125.99±4.78 mg QE/g dw), ABTS•⁺ (15.22±1.82 to 211.33± 3.21 mg/L), DPPH• (19.03± 0.40 to 280.33± 2.08 mg/L) and FRAP (0.19±0.01 to 1.30±0.15 mM/L) antioxidant activities of the various extracts were determined and considered as responses. The optimal extraction conditions were obtained at a temperature of 46° C, a duration of extraction of 9h, and for a methanol proportion of 93 %. The corresponding predicted values were 187.79 mg GAE/g dw, 99.90 mg QE/g dw, 23.57 mg/L, 23.10 mg/L and 0.78 mM/L for TPC, TFC, ABTS•⁺, DPPH• and FRAP, respectively.
Keywords :
Thymelaea hirsuta L. , phenolic compounds , antioxidant activity , RSM
