Bioactive Phenolic Metabolites from Adriatic Brown Algae <i>Dictyota dichotoma</i> and <i>Padina pavonica</i> (Dictyotaceae)

• Main Authors: Ivana Generalić Mekinić, Vida Šimat, Viktorija Botić, Anita Crnjac, Marina Smoljo, Barbara Soldo, Ivica Ljubenkov, Martina Čagalj, Danijela Skroza
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Foods
• Subjects: antioxidants; biological activity; brown seaweeds; extraction mode; phenolic compounds
• Online Access: https://www.mdpi.com/2304-8158/10/6/1187

In this study, the influences of temperature (20, 40 and 60 °C) and extraction solvents (water, ethanol) on the ultrasound-assisted extraction of phenolics from the Adriatic macroalgae <i>Dictyota dichotoma</i> and <i>Padina pavonica</i> were studied. The extracts were analysed for major phenolic sub-groups (total phenolics, flavonoids and tannins) using spectrometric methods, while the individual phenolics were detected by HPLC. The antioxidant activities were evaluated using three methods: Ferric Reducing/Antioxidant Power (FRAP), scavenging of the stabile 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and Oxygen Radical Antioxidant Capacity (ORAC). The aim of the study was also to find the connection between the chemical composition of the extracts and their biological activity. Therefore, principal component analysis (PCA), which permits simple representation of different sample data and better visualisation of their correlations, was used. Higher extraction yields of the total phenolics, flavonoids and tannins were obtained using an alcoholic solvent, while a general conclusion about the applied temperature was not established. These extracts also showed good antioxidant activity, especially <i>D. dichotoma</i> extracts, with high reducing capacity (690–792 mM TE) and ORAC values (38.7–40.8 mM TE in 400-fold diluted extracts). The PCA pointed out the significant influence of flavonoids and tannins on the investigated properties. The results of this investigation could be interesting for future studies dealing with the application of these two algae in foods, cosmetics and pharmaceuticals.