Supercritical extract from the Japanese sea brown algae <i>Undaria pinnatifida</i> as a source of bioactive compounds

Abstract

Bioactive compounds contained in algae have practical applications in the pharmaceutical industry, production of human food and animal feed, and other fields. Since brown algae contain a wide range of bioactive substances, producing high-quality and chemically safe extracts on their basis is an urgent task. This study was aimed at characterization of supercritical extract from the corresponding algae, as well as the identification and evaluation of the content of bioactive compounds. The content of carotenoids, phenolic compounds and mannitol was determined by UV-Vis spectroscopy; a fatty acid analysis was carried out by GLPC; the qualitative composition of carotenoids and phenolic compounds was analyzed by HPLC. Supercritical CO2 extraction of the brown alga U. rinnatifida with EtOH as a polar modifier is characterized by high ejection efficiency of fatty acids, phenolic compounds and carotenoids. The latter profile of the collected supercritical extract consists of 14 representatives. In particular, fucoxanthin (58.1% of the sum), zeaxanthin (12.6% of the sum), and fucoxanthinol (14.5% of the sum) are the most abundant compounds. Palmitic acid, oleic acid, arachidonic acid, and eicosapentaenoic acids are the main of the 20 fatty acids found in the corresponding extract. However, the class of polyunsaturated fatty acids is predominant, which content of the ώ-6 and ώ-3 groups does not differ significantly. The total content of phenolic compounds is 13.45+0.43 mg/g of gallic acid equivalent. For instance, the most represented phenolic substances are epicatechin, epigallocatechin gallate, syringic acid, coumaric acid, ferulic acid and salicylic acid.