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.

Graphical abstract

中文翻译：

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独立和组合的微藻水提取物的体外抗胆固醇和抗氧化活性

藻类因其治疗特性而被用作重要的医学来源之一。食用藻类和食用藻类被认为是可以提供蛋白质，碳水化合物，维生素，矿物质盐，类胡萝卜素和抗氧化剂适当平衡的完整食品。当前研究的目的是评估不同海洋微藻物种（螺旋藻，稻鱼腥藻，斜生藻和寻常绿藻）的热水提取物。）体外或单独或组合使用可降低胆固醇。从不同的海洋微藻物种制备藻类提取物（AEs），并通过分光光度法评估其体外抗胆固醇活性。分别使用Folin-Ciocalteu，DPPH，香草醛-HCl测定法定量藻类生长及其生物活性成分（多酚含量，抗氧化能力和单宁含量）。21天后，在1000 mL培养基中记录了S. platensis的最高生物量浓度值（1.367 g）。在浓度为15 mg / mL的情况下，长达60分钟观察到链球菌提取物的抗胆固醇活性均增加，最高抑制率为76.01％（p <0.05）。在相同的温育期后，板蓝假单胞菌与寻常小球藻的组合提取物显示出最大的降胆固醇作用（77.95％）值（p <0.05）。植物化学物质的筛选表明丹宁在所有海藻提取物的存在下，在最高单宁含量螺旋藻（4.66微克TAE /克DW）中，随后米曲霉与（2.99微克/克）和斜生栅藻（2.13微克/ g），米曲霉提取物含有最高浓度的酚类化合物（503.67μgGAE / g）。通过获得了最高的抗氧化活性螺旋藻提取物（92.66％）的值（p 为15毫克/毫升<0.05），而至少一种被观察斜叶链球菌（16.81％）。推荐将S. platensis的提取物单独使用或与寻常提取物组合使用，是具有抗胆固醇和抗氧化潜力的天然生物活性来源。

图形概要