Exploration of using the algal bioactive compounds for cosmeceuticals and pharmaceutical applications

Abstract

Purpose The research is aimed at describing the extraction and determination methods of carotenoids, fatty acids, phenolic, flavonoids, proteins, and carbohydrates as bioactive compounds from different microalgae species grown in different media. Materials and methods The microalgae used in this study are Scenedesmus spp. and Spirulina platensis, which are microalgae species of freshwater; Dunaliella salina and Oscillatoria limnetica, which are of salt stress media; and microalgae community Bloom of municipal wastewater plant at Zenin, Giza. Carotenoids were extracted using jojoba oil as fatty oil, and their contents were determined using high-performance liquid chromatography analysis. From the cell residue, total lipid was extracted by ultrasonic bath with cosolvent mixture of n-hexane and isopropanol (3 : 2 v/v). The fatty acid profile is determined by gas chromatographic analysis. Phenolic contents are determined with Folin–Ciocalteu reagent after preparing the ethanolic extract. Methanolic extraction was done for determination of total flavonoid contents by colorimetric method. Total protein was determined by Kjeldahl method, and finally, total carbohydrate content is evaluated after extraction with barium carbonate by spectrophotometer at 485 nm. Results and conclusion The results of each assay showed that D. salina and O. limnetica accumulated carotenoids more than microalgae cells of Bloom, which have carotenoids content more than Scenedesmus spp. and S. platensis (151.4, 136.3, 123.4, 11.93, and 7.5 μg/g, respectively). Gas chromatographic analysis of extracted lipid exhibited the high percentage of polyunsaturated fatty acids (ω-3 and ω-6) found in O. limnetica and Bloom. Total phenolic compounds were presented in amounts higher than flavonoids in all the studied strains. All of the biomass of microalgae that was subject to analysis had a relatively high protein content, where Scenedesmus spp. had the highest value (210 mg/g) and D. salina the lowest (21.5 mg/g. The total carbohydrate content, which plays an important role in cosmetics products, was detected at the highest concentration in Scenedesmus spp. (6.6 mg/g), followed by S. platensis (6.0 mg/g), O. limnetica (3.5 mg/g), D. salina (2.3 mg/g), and Bloom (1.5 mg/g). The results obtained in this study prove that microalgae are a rich source of bioactive compounds for pharmaceutical and cosmeceutical industries.