AO-13: Phenolic Compounds of algae (Ulva lactuca): Optimization of extraction by response surface methodology and in vitro antioxidant properties

Abstract

Subject description: Seaweeds are a rich source of natural antioxidants with potent antioxidant properties. While the one-factor method has limitations in optimizing the phenolic extract, the use of developed mathematical models such as Response Surface Methodology (RSM) is recommended for more effective optimization processes. Objectives: Given the highly bioactive nature of phenolics and their numerous therapeutic applications, the primary objective of this investigation is to optimize their recovery using Response Surface Methodology (RSM). Methods: Prior to RSM, the single-factor method was applied to reveal the main factors influencing the extraction (solvent type and concentration, sample˗to˗solvent ratio, temperature, and time of extraction). 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 of the preliminary optimization step through sequential methodology revealed that solvent concentration, extraction duration, and temperature were the main influencing factors. All these tested extraction parameters significantly influenced total phenolic contents (TPC) and DPPH-free radical scavenging activity (FRSA) and ferric reducing power (FRP). RSM analysis using Box˗Behnken design showed that the optimal extraction conditions of total phenolic contents of algae were 23.07% acetone, 51.82 °C, and 118.02 min with values of 29.44 mg GAE/g for total phenolic extracts, 59.48% and FRSA, and 123.45 mg AAE/100g for FRP. 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. Conclusion: The developed mathematical models have demonstrated a high level of significance through sequential and RSM optimization processes for phenolic antioxidants of Ficus carica leaves. This method allows us to observe the effects of different extraction conditions on the phenolic antioxidants