Exploring Ulva australis Areschoug for possible biotechnological applications: In vitro antioxidant and enzymatic inhibitory properties, and fatty acids contents

Ulva australis Areschoug (Ulvales, Chlorophyta) is traditionally used as a foodstuff in Korea and to treat several diseases, such as hyperlipidemia and urinary ailments. It is now considered an invasive species of the Venice Lagoon (Italy). This work explored U. australis as a potential source of bioactive molecules with biotechnological applications. For that purpose, organic and water extracts were prepared from dried biomass of U. australis and evaluated for radical scavenging activity (RSA), metal chelating activities and for in vitro inhibition of enzymes related with several disorders, namely Alzheimer's disease (acetylcholinesterase, butyrylcholinesterase), hyperpigmentation (tyrosinase), obesity (lipase), Type-2 diabetes mellitus (α-glucosidase, α-amylase) and skin sagging (elastase). Extracts were also evaluated for total contents of phenolics, flavonoids condensed tannins and carbohydrates. Finally, the fatty acids methyl esters profile of the biomass was established by gas chromatography–mass spectrometry. Extracts had low to moderate radical scavenging activity on DPPH, and a higher ability to chelate Fe2+ than Cu2+, and the maximum Fe2+ chelating capacity was observed in the tincture (IC50 = 4.82 mg/mL). Samples had a higher ability to inhibit α-amylase and microbial α-glucosidase than the other tested enzymes. The biomass of U. australis presented a highly saturated fatty acids profile, enriched in palmitic acid. These data suggest U. australis as a promising source of natural products with anti- diabetic properties and as a desirable species for biodiesel production.