Isolation and determination of phenolic compounds from freshwater Cladophora glomerata

Abstract

Marine algae biomass has gained widespread interest in the world of science and many industries. The growing number of publications proves that these algae are an interesting and essential natural resource. This interest is due to the presence of a variety of biologically active compounds that give algae extracts a broad spectrum of biological and functional properties. However, there is little data on the chemical composition of algae obtained from freshwater. This work focuses on the isolation and determination of phenolic compounds from freshwater algae of the species Cladophora glomerata. Different types of extraction and extractants were used to isolate these bioactive compounds. For the first time, the impact of the extraction type and the kind of solvent on the efficiency of antioxidant isolation from freshwater algae was determined. Three types of extraction and five different solvents with different polarity were used to isolate antioxidants, including phenolic compounds. The obtained results show that the microwave-assisted extraction with water was the most effective for isolation of phenolic compounds and antioxidants. The extracts were analysed for the assessment of their antioxidant activity, which is one of the commonly described properties of phenolic compounds. The analysis was carried out using colourimetric and spectrophotometric methods as well as the method of high-performance liquid chromatography. Regardless of the extraction method and extractant used, both phenolic acids and flavonoids, were determined in all tested extracts. Nine phenolic compounds (gallic acid, chlorogenic acid, syringic acid, p-coumaric acid, myricetin, 3,4-dihydroxybenzoic acid, vanillic acid, 4-hydroxybenzoic acid and rutin) were identified using qualitative analysis by high-performance liquid chromatography. These studies show that algae extracts have great potential in the cosmetics, pharmaceutical or agricultural industries. They can be valuable components of many products that protect against free radical attack and also prevent diseases associated mainly with oxidative stress.