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

Chai Siah Ku, Bohkyung Kim, Tho X. Pham, Yue Yang, Curtis L. Weller, Timothy P Carr, Young Ki Park, Ji Young Lee

Research output: Contribution to journalArticle

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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-1α, 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.

Original languageEnglish (US)
Pages (from-to)1214-1222
Number of pages9
JournalJournal of Medicinal Food
Volume18
Issue number11
DOIs
StatePublished - Nov 1 2015

Fingerprint

Nostoc commune
Intestinal Absorption
Cyanobacteria
Inbred C57BL Mouse
Spirulina
Cholesterol
Lipids
Liver
Gene Expression
Oxidoreductases
Triglycerides
Sterol Regulatory Element Binding Protein 2
Acyl-CoA Oxidase
Carnitine O-Palmitoyltransferase
Fatty Acid Synthases
LDL Receptors
Hep G2 Cells
Sterols
Lipid Metabolism
Hepatocytes

Keywords

  • Blue-green algae
  • Hypolipidemia
  • Nostoc commune var
  • Sphaeroids Kützing
  • Spirulina platensis

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

Hypolipidemic Effect of a Blue-Green Alga (Nostoc commune) Is Attributed to Its Nonlipid Fraction by Decreasing Intestinal Cholesterol Absorption in C57BL/6J Mice. / Ku, Chai Siah; Kim, Bohkyung; Pham, Tho X.; Yang, Yue; Weller, Curtis L.; Carr, Timothy P; Park, Young Ki; Lee, Ji Young.

In: Journal of Medicinal Food, Vol. 18, No. 11, 01.11.2015, p. 1214-1222.

Research output: Contribution to journalArticle

Ku, Chai Siah ; Kim, Bohkyung ; Pham, Tho X. ; Yang, Yue ; Weller, Curtis L. ; Carr, Timothy P ; Park, Young Ki ; Lee, Ji Young. / Hypolipidemic Effect of a Blue-Green Alga (Nostoc commune) Is Attributed to Its Nonlipid Fraction by Decreasing Intestinal Cholesterol Absorption in C57BL/6J Mice. In: Journal of Medicinal Food. 2015 ; Vol. 18, No. 11. pp. 1214-1222.
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abstract = "We previously demonstrated that Nostoc commune var. sphaeroids K{\"u}tzing (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-1α, 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.",
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AU - Kim, Bohkyung

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