Total phenolic and flavonoids contents and in vitro evaluation of antioxidant activity of several Calendula officinalis (Marigold) extracts

The search for natural antioxidants to replace synthetic antioxidants is one of humanity’s health priorities. Medicinal and Aromatic Plants (MAP) contain phenolic compounds that act as natural antioxidants. The aim of this work is to study total phenols and flavonoids contents and evaluate the antioxidant power of various extracts of Calendula officinalis. Extracts were prepared in two steps: hot solid-liquid extraction, by Soxhlet and from the plant powder using a solvent (Methanol/water 70/30, Acetone/water 70/30) followed by a liquid-liquid extraction by splitting the obtained extract by two increasingly polarized solvents (Ethyl acetate and Butanol). Total phenols and flavonoids were evaluated using gallic acid and quercetin as standards, respectively. The antioxidant activity of extracts was determined by DPPH (2,2-diphényl 1-picrylhydrazyle) free radical reduction method. The two crude fractions of Methanol and Acetone presented the highest levels of total phenols (7,58±0,38 mg GAE/g dm and 6,80±0,34 mg GAE/g dm respectively), and flavonoids (7,37±0,37 mg QE/g dm and 7,93±0,40 mg QE/g dm respectively). Ethyl acetate fractions showed a high antioxidant activity. This study demonstrated that extracts from Calendula officinalis flowers present a promising source of natural antioxidant.