Effect of dietary fenugreek seeds on biliary proteins that influence nucleation of cholesterol crystals in bile

Formation of cholesterol gallstones in gallbladder is controlled by procrystallising and anticrystallising factors present in bile. Dietary fenugreek seed has been recently observed to possess anti-lithogenic potential in experimental mice. In the current animal study, we evaluated the effect of dietary fenugreek on the compositional changes in the bile, particularly its effect on glycoproteins, low-molecular-weight (LMW) and high-molecular-weight (HMW) proteins, cholesterol nucleation time and cholesterol crystal growth. Groups of Wistar rats were fed for 10 weeks with diets: (1) basal control (C), (2) C+fenugreek (12%), (3) high cholesterol diet (HCD) and (4) HCD+fenugreek (12%). Feeding of HCD containing 0.5% cholesterol for 10 weeks rendered the bile lithogenic. Incorporation of fenugreek into HCD decreased the cholesterol content (70.5%), total protein (58.3%), glycoprotein (27.5%), lipid peroxides (13.6%) and cholesterol saturation index (from 1.98 to 0.75) in bile, increased the bile flow rate (19.5%), prolonged the cholesterol nucleation time and reduced the vesicular form of cholesterol (65%), which was accompanied with an increase in smaller vesicular form (94%). There was an increase in biliary phospholipid (33%) and total bile acid (49%) contents in the HCD+fenugreek group as compared with the HCD group. Electrophoretic separation of biliary LMW proteins showed the presence of a high concentration of 28-kDa protein, which might be responsible for the prolongation of cholesterol nucleation time in the fenugreek-fed groups. These findings indicate that the beneficial anti-lithogenic effect of dietary fenugreek, which primarily is due to reduction in the cholesterol content in bile, was additionally affected through a modulation of the nucleating and anti-nucleating proteins, which, in turn, affect cholesterol crystallisation.