EVALUATION OF PHYTOCHEMICAL AND ANTIOXIDANT ACTIVITIES OF ORIGANUM, CISTUS AND THYMUS SPECIES
Kamal El Yousfi, Houria Misbahi, Hassane Greche and Meryem Boudkhili*
ABSTRACT
The aim of this study was to evaluate antioxidant properties of four plants from North of Morocco then to quantify phenolic compounds and flavonoids in each plant extracts. The air-dried leaves of Origanum elongatum, Cistus salvifolius, Thymus willdenowii, Boiss and Cistus laurifolius were extracted with methanol and ethyl acetate by ultrasonic apparatus. The antioxidant effect of plant extracts was assessed using a modified 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and the quantification of phenolic compounds and flavonoids was performed by Folin Ciocalteu and alumunium trichloride reagents, respectively. The antioxidant effect of all samples, measured by calculating IC50 for the DDPH method, ranged from 0.27 μg/ml to 1.7 μg/ml whereas IC50 of the reference BHT was 0.67 mg/ml. The total phenolic content, analyzed using Folin–Ciocalteu’s reagent, of the samples varied from 46.6 μg/100 mg to 153 μg/100 mg dry weight, expressed as gallic acid equivalents (GAE). The total flavonoid concentrations, detected using 2% aluminum chloride, varied from 3.63 to 5.54 μg equivalents (RE)/mg dry weight. The results obtained showed that the antioxidant activity of plant extracts could be correlated to the total phenolic content and the total flavonoids. In addition, Origanum elongatum that showed highest antioxidant activity had the highest phenolic and flavonoids contents. The evaluation of the antioxidant by the DPPH test revealed that all tested extracts have antioxidant properties and that methanol extracts are the most active. Origanum elongatum methanolic extract showed the best scavenging activity (IC50 = 0.267 ± 0.06 μg / ml).
Keywords: Origanum elongatum, Cistus salvifolius, Thymus willdenowii, Boiss and Cistus laurifolius.
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