Maximizing the Antioxidant Capacity of Padina pavonica by Choosing the Right Drying and Extraction Methods

Abstract

Marine algae are becoming an interesting source of biologically active compounds with a promising application as nutraceuticals, functional food ingredients, and therapeutic agents. The effect of drying (freeze-drying, oven-drying, and shade-drying) and extraction methods (shaking at room temperature, shaking in an incubator at 60 °C, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE)) on the total phenolics content (TPC), total flavonoids content (TFC), and total tannins content (TTC), as well as antioxidant capacity of the water/ethanol extracts from Padina pavonica were investigated. The TPC, TFC, and TTC values of P. pavonica were in the range from 0.44 ± 0.03 to 4.32 ± 0.15 gallic acid equivalents in mg/g (mg GAE/g) dry algae, from 0.31 ± 0.01 to 2.87 ± 0.01 mg QE/g dry algae, and from 0.32 ± 0.02 to 10.41 ± 0.62 mg CE/g dry algae, respectively. The highest TPC was found in the freeze-dried sample in 50% ethanol, extracted by MAE (200 W, 60 °C, and 5 min). In all cases, freeze-dried samples extracted with ethanol (both 50% and 70%) had the higher antioxidant activity, while MAE as a green option reduces the extraction time without the loss of antioxidant activity in P. pavonica.

Bioactive Phenolic Metabolites from Adriatic Brown Algae Dictyota dichotoma and Padina pavonica (Dictyotaceae)

“…Although there were no significant differences between the phenolic potential of the D. dichotoma and P. pavonica water extracts, the content of phenolics in the ethanolic extracts was significantly higher. Other authors also investigated phenolics from D. dichotoma [ 2 , 23 , 34 , 35 , 36 ] and P. pavonica [ 3 , 22 , 23 , 33 , 34 ], but comparison of the results is difficult due to the employment of different extraction protocols (solvents used, time of extraction, temperature, additional actions such as stirring, use of novel techniques, etc.) or due to results’ expression using different standard compounds.…”

“…or due to results’ expression using different standard compounds. However, the results of our study on the influence of drying and extraction methods on P. pavonica phenolics showed better extraction yields in water extracts (more than twofold higher results were obtained) [ 23 ]. Figure 1 b also shows the distribution of flavonoids among samples.…”

“…It can be seen that the ethanolic extracts are richer in these valuable compounds, especially extracts of D. dichotoma (concentration range from 871 mg QE/L in extract prepared at 60 °C to 975 mg QE/L in extract prepared at RT). Kosanic et al [ 22 ] also reported a higher content of flavonoids in extracts of D. dichotoma than in P. pavonica, while Čagalj et al [ 23 ] obtained a higher content of flavonoids in ethanolic extracts. All other samples contained significantly lower amounts, from 23 to 160 mg QE/L.…”

“…Therefore, there is an increasing trend toward the investigation of novel, environmentally friendly extraction technologies for the preparation of highly valuable extracts. Among the different new technologies, the use of ultrasound-assisted extraction is probably one of the easiest, cheapest and, consequently, most widely used [ 5 , 15 , 18 , 23 ].…”

Seasonal Changes in Essential Oil Constituents of Cystoseira compressa: First Report

“…Studies on marine algae are usually focused on the isolation of structurally different bioactive compounds like polysaccharides (e.g., fucoidan, alginate, and laminarin), photosynthetic pigments (carotenoids, chlorophylls, and phycobilins), sterols, polyphenolics, etc. [3][4][5][6][7][8][9]. In comparison to the research on these non-volatile compounds, studies on volatiles of marine origin are still scarce.…”