Anti-cholesterol and Antioxidant Activities of Independent and Combined Microalgae Aqueous Extracts In Vitro

Abstract

Algae are used as one of important medical sources for its therapeutic properties; and edible algae are acknowledged as complete foods which provide right balance of proteins, carbohydrates, vitamins, mineral salts, carotenoids, and antioxidants. The aim of the current study was to evaluate hot-water extracts of different marine microalgae species (Spirulina platensis, Anabaena oryzae, Scenedesmus obliquus and Chlorella vulgaris) in vitro for their cholesterol-lowering activity, individually or in combinations. The algal extracts (AEs) were prepared from different marine microalgae species and their in vitro anti-cholesterol activities were assessed spectrophotometrically. The algal growth and their bioactive constituents (polyphenol content, antioxidant capacity and tannin content) were quantified using Folin-Ciocalteu, DPPH, vanillin-HCl assays, respectively. The highest value of the biomass concentration (1.367 g) was recorded for S. platensis in 1000 mL of culture media after 21 days. Increasing anti-cholesterol activity by S. platensis extract was observed up to 60 min at a concentration of 15 mg/mL and a highest inhibition was found as 76.01% value (p < 0.05). The combined extracts from S. platensis with C. vulgaris showed maximum cholesterol-lowering effect (77.95%) value (p < 0.05), after the same incubation period. The phytochemical screening indicated the presence of tannins in all algal extracts, with highest tannin contents in S. platensis (4.66 μg TAE/g DW), followed by A. oryzae with (2.99 μg/g) and S. obliquus (2.13 μg/g), A. oryzae extract contained the highest concentration of phenolic compounds (503.67 μg GAE/g). The highest antioxidant activity was obtained by S. platensis extract (92.66%) value (p < 0.05) at 15 mg/mL, while the least one was observed by S. obliquus (16.81%). The extract of S. platensis, used individually or combined with C. vulgaris extract, is recommended as natural bioactive source, with anti-cholesterol and antioxidant potentialities.