Hypolipidemic effect of a blue‐green alga, Nostoc commune var. Sphaeroides Kützing, is attributed to algal residue but not lipid extract in C57BL/6J mice

Abstract

We previously reported a hypolipidemic effect of an edible blue‐green alga (BGA), Nostoc commune var. Sphaeroides Kützing (NO) in mice. To further evaluate whether the lipid‐lowering effect of NO is attributable to algal residue or lipid extract (LE), male C57BL/6J mice were fed an AIN‐93M diet supplemented with 2.5% and 5% by wt of whole algae or LE equivalent amount present in 5% whole algae for 4 wk. Spirulina Platensis (SP), the most common BGA for human consumption, was also tested for comparison. Plasma total cholesterol and triglyceride were significantly lowered in whole NO‐fed animals but not in NO LE and SP groups. Hepatic total cholesterol and triglyceride levels were not significantly different between groups but free cholesterol was higher in NO 2.5% and all SP‐fed groups. Expression of hepatic genes for cholesterol metabolism, such as HMG CoA reductase and sterol regulatory element binding protein‐2, was significantly increased in 5% NO group. Lipogenic gene expression in the liver was not altered in all groups whereas carnitine palmitoyl transferase I and acyl‐CoA oxidase mRNA levels were induced in 5% NO group. Significant reduction in intestinal cholesterol absorption was also observed in whole NO groups. In conclusion, NO algal residue contains bioactive components that inhibit intestinal cholesterol absorption and consequently exert a hypolipidemic effect in mice.Grant Funding Source: NIH R21AT005152