Chemical Composition and Evaluation of Antioxidant, Antimicrobial and Cytotoxic Activities of Moroccan Cladanthus mixtus Essential Oil and Extracts

Abstract

The methanolic and deodorized aqueous extracts of the Moroccan Cladanthus mixtus collected from Bouznika were studied for its antioxidant, antimicrobial and cytotoxic activities. The essential oil was isolated by hydrodistillation and analyzed using GC/FID and GC/MS. The major component found was 2-methyl-2, trans-butenyl methacrylate (34 %). The essential oil showed good antioxidant activity for DPPH (IC50 =0.342±0.002 mg/mL) and a strong antimicrobial activity against all the tested microorganisms. Although, the deodorized aqueous extract had a high amount of phenols (38.2±0.4 mg GAE/g), it has shown no inhibiting effect against the growth of tested bacterial strains. The methanolic extract of C. mixtus which was characterized with higher flavonoid content (3.2 ±0.01 mg QE/g) was analyzed by the HPLC and showed the presence of gallic, vanillic, caffeic and syringic acids and catechin. For the methanolic extract, higher antioxidant activity was recorded than the deodorized aqueous extract using DPPH test (IC50 = 1.933 ± 0.048 mg/mL) and ABTS test (IC50 = 2.030 ± 0.006 mg/mL). The essential oil showed good cytotoxic activity with an IC50 = 85.27 μg/mL greater than that of the methanol extract (IC50 = 125.5 μg/mL). The apigenin (42 , 5, 7,-trihydroxyflavone), a natural compound, isolated for the first time from C. mixtus, showed a great cytotoxic activity (IC50 = 17.9 μg/mL). The 7, 4'-dipropargyl ether, a semi synthetic derivative of apigenin obtained by alkylation reaction of apigenin, showed a lower cytotoxic activity (IC50 = 88 μg/mL) than apigenin. This present study also elucidated the role of hydroxyl groups at positions C7 and C4’on the cytotoxic activity.