Hypolipidemic Effect of a Blue-Green Alga (Nostoc commune) Is Attributed to Its Nonlipid Fraction by Decreasing Intestinal Cholesterol Absorption in C57BL/6J Mice

Abstract

We previously demonstrated that Nostoc commune var. sphaeroids Kützing (NO), a blue-green alga (BGA), exerts a hypolipidemic effect in vivo and its lipid extract regulates the expression of genes involved in cholesterol and lipid metabolism in vitro. The objective of this study was to investigate whether the hypolipidemic effect of NO is attributed to an algal lipid or a delipidated fraction in vivo compared with Spirulina platensis (SP). Male C57BL/6J mice were fed an AIN-93M diet containing 2.5% or 5% of BGA (w/w) or a lipid extract equivalent to 5% of BGA for 4 weeks to measure plasma and liver lipids, hepatic gene expression, intestinal cholesterol absorption, and fecal sterol excretion. Plasma total cholesterol (TC) was significantly lower in 2.5% and 5% NO-fed groups, while plasma triglyceride (TG) levels were decreased in the 5% NO group compared with controls. However, neither NO organic extract (NOE) nor SP-fed groups altered plasma lipids. Hepatic mRNA levels of sterol regulatory element-binding protein 2, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), carnitine palmitoyltransferase-1a, and acyl-CoA oxidase 1 were induced in 5% NO-fed mice, while there were no significant changes in hepatic lipogenic gene expression between groups. NO, but not NOE and SP groups, significantly decreased intestinal cholesterol absorption. When HepG2 cells and primary mouse hepatocytes were incubated with NOE and SP organic extract (SPE), there were marked decreases in protein levels of HMGR, low-density lipoprotein receptor, and fatty acid synthase. In conclusion, the nonlipid fraction of NO exerts TC and TG-lowering effects primarily by inhibiting intestinal cholesterol absorption and by increasing hepatic fatty acid oxidation, respectively.

Nostoc sphaeroids Kütz powder ameliorates diet-induced hyperlipidemia in C57BL/6j mice

“…Then, after 4 weeks of HFD, the mice received an HFD supplemented with NO (2.5%), NO (7.5%), or without NO for 6 weeks. This study shows that supplementing diet with NO significantly reduces TC, TG, and LDL, and increases HDL in serum (Table 4), which is consistent with a previous study finding that NO treatment significantly lowered plasma lipid (18). Although the serum lipid levels have not reached the control levels, it still shows that NO exerts a positive effect towards ameliorating lipids and has the potential to prevent hyperlipidemia in mice.…”

“…They also have bioactive properties, such as antiviral, antitumor, antidiabetic, anti-inflammatory, and lipid-modulating effects (15,16). Previous studies have shown that NO and its extracts significantly reduced plasma total cholesterol (TC) and triglyceride (TG) levels in male C57BL/6j mice and may have the potential to reduce the risk of atherosclerosis (16)(17)(18). Nevertheless, it remains unknown whether NO could have any effect on body weight or regulatory effects on liver lipid accumulation.…”

Nostoc sphaeroids Kütz ameliorates hyperlipidemia and maintains the intestinal barrier and gut microbiota composition of high‐fat diet mice

“…N. sphaeroides Kütz, also known as Ge‐Xian‐Mi in China, has been used as a health product for centuries (Hao et al, 2011; Ku et al, 2013). N. sphaeroides Kütz is high in polysaccharide, amino acid, protein, vitamin, and mineral contents (Yang et al, 2011), and has bioactive properties, including antiviral, antitumor, antidiabetic, anti‐inflammatory, and lipid‐modulating activities (Ku, Kim, Pham, Yang, Wegner, et al, 2015; Ku, Kim, Pham, Yang, Weller, et al, 2015; Ku et al, 2013). Previous studies have shown that N. sphaeroides Kütz and its extracts significantly reduced plasma TC and TG levels in male C57BL/6j mice and may reduce atherosclerosis risk (Ku, Kim, Pham, Yang, Weller, et al, 2015; Yang, Kim, Park, & Lee, 2014).…”

Association between Cholesterol Homeostasis with Intestinal Proteins, Enzymes and Drugs in Absorption of Cholesterol and its Relationship with Vascular Diseases: A Review

“…Pravastatin (PR) treatment reduced duodenal cholesterol transporter expression in mice. PR-induced increases in liver X receptor may be involved in reduction of Niemann-Pick C1-like 1 expression, lowers the intestinal cholesterol absorption [33].…”

“…Further studies reveal that Anacetrapib (ANA) promotes pre β High Density Lipoprotein in vivo functionality, but has no effects on absorption of cholesterol [37]. Another study showed that the nonlipid fraction of Nostoc commune var.…”