Animal experiment:

Mice[2]For atherosclerosis studies, 8-wk-old female LDLRKO mice are fed a Western diet (21% fat, 0.15% cholesterol; TD.88137) for 8 wk. One group of mice (baseline group) is euthanized at this time point for lesion measurement in the aortic root region and in the innominate artery. Atherosclerotic lesion in the whole aorta is not examined in the baseline group. The remaining mice are then divided into 2 groups and fed the following diets for another 15 wk before euthanasia: group 1, chow diet (5% fat, AIN-76A Rodent Diet); and group 2, chow diet + 1.25% (wt/wt) Hyodeoxycholic acid. For other studies, 8-wk-old female LDLRKO mice are fed a chow diet or chow diet + 1.25% Hyodeoxycholic acid for 3 wk before phenotype measurements. Food consumption and body weight are recorded weekly. Animals are measured for total body fat mass and lean mass by magnetic resonance imaging (MRI) using Bruker Minispec with software from Eco Medical Systems[2].

Hyodeoxycholic acid is a secondary bile acid formed in the small intestine by the gut flora, and acts as a TGR5 (GPCR19) agonist, with an EC50 of 31.6 μM in CHO cells.

Hyodeoxycholic acid is a secondary hydrophilic bile acid formed in the small intestine by the gut flora, and acts as an agonist of TGR5, with an EC50 of 31.6 μM in CHO cells[1]. Hyodeoxycholic acid (50, 100 μM) increases the expression of genes (Abca1, Abcg1, and Apoe) involved in cholesterol efflux in RAW 264.7 cells[2].

Hyodeoxycholic acid (HDCA; 1.25% (wt/wt)) obviously decreases fat mass and increases lean mass but does not raise the serum levels of any organ toxicity markers in LDLRKO mice. Hyodeoxycholic acid inhibits atherosclerotic lesion formation in LDLRKO at multiple sites, improves plasma lipoprotein profiles, decreases plasma glucose level and intestinal cholesterol absorption efficiency and increases daily cholesterol excretion through fecal output. Hyodeoxycholic acid also improves HDL function as measured by a cholesterol efflux assay[2].

References:
[1]. Sato H, et al. Novel potent and selective bile acid derivatives as TGR5 agonists: biological screening, structure-activity relationships, and molecular modeling studies. J Med Chem. 2008 Mar 27;51(6):1831-41.
[2]. Shih DM, et al. Hyodeoxycholic acid improves HDL function and inhibits atherosclerotic lesion formation in LDLR-knockout mice. FASEB J. 2013 Sep;27(9):3805-17.