Résumé:
Subject description: The procedure for the extraction of total polyphenols is influenced by several
parameters such as the chemical nature of these compounds, the appropriate extraction method, the
solvent used, particle size, extraction time, and temperature.
Objectives: The objective of this study is to study the effect extraction conditions on the recovery
of phenolic compounds and in vitro antioxidant properties algae (Ulva lactuca)
Methods: The effects of solvent type (acetone, ethanol, methanol, and water), solvent
concentration (20-100%), sample/solvent ratio (0.2/20 - 1 mg/20 g/ml), extraction time (30-150 min), and
temperature (25-90°C) on the extraction of total polyphenols and the antioxidant activity of algae were
evaluated. The contents of total polyphenols (TP) and flavonoids were determined. While the ferric
reducing power (FRP) and the free radical scavenging activity (DPPH) were used to evaluate the
antioxidant activity of the extracts.
Results and discussion: The results obtained show that the extraction conditions have a significant
effect (p<0.05) on the content of total polyphenols, flavonoids, and the antioxidant activity of the extracts.
The optimal extraction conditions are as follows: 60% acetone, 0.2 g/20 ml, 90 min, and 90°C, with values
of 11.89 g GAE/100 g for total phenolic contents, 90.43 g AAE/100 g for ferric reducing power, and
70.23 g % for free radical scavenging activity (DPPH). Ferric-reducing and free radical scavenging
potentials were found to be positively significantly correlated with phenolic content under the influence
of all extraction parameters.
Conclusion: Seaweeds are indeed a rich source of natural antioxidants with a strong antioxidant
property. The one-factor method has limitations in optimizing the phenolic extract, the use of developed
mathematical models like RSM (Response Surface Methodology) is recommended for more effective
optimization processes
