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.
Highlights
Published: 27 March 2021Among different brown algae from the genus Padina, Padina pavonica is one of the most common species that inhabits coastal intertidal zones
The freeze-dried sample extracted with water using ultrasound-assisted extraction (UAE) and microwaveassisted extraction (MAE) had the highest total tannins content (TTC). These results showed that the two green, novel extraction methods yielded higher total flavonoids content (TFC) and TTC amounts, and it was evident that MAE yielded more TFC in a shorter extraction time
When comparing solvents used for extraction, the results showed that water/ethanol mixtures were more suitable for maintaining high diphenyl-1-picrylhydrazyl radical scavenging ability (DPPH) scavenging activity of investigated algal samples, especially 50% ethanol
Summary
Among different brown algae from the genus Padina (family Dictyotaceae, order Dictyotales), Padina pavonica is one of the most common species that inhabits coastal intertidal zones This alga is growing mainly in the Mediterranean Sea and Atlantic Ocean while it is distributed in tropical and temperate seas worldwide [1,2,3]. Phenolics, a group of secondary metabolites produced by algae as a response to harsh environmental conditions, are the most important bioactive compounds found in brown algae [9]. They are the primary components of algae cell walls while they have a role as a chemical defence against herbivores, bacteria, and fouling organisms [4]. The biological activity of phenolic compounds from terrestrial plants has been
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