Hypocholesterolemic Effects of Soybean and Sweet Lupine Tempeh in Hypercholesterolemic Rats

A study was designed to evaluate the hypocholesterolemic effects of soybean and sweet lupine tempeh fermented with Rhizopus oligosporus in hypercholesterolemic rats. Soybean and sweet lupine seeds and Rhizopus oligosporus were used in this study to produce tempeh using traditional method. Both types of tempeh were subjected to biological study. Thirty-six male albino rats of Sprague-Dawley strain were divided into 6 groups as follows: (1) control negative (C-); (2) hypercholesterolemic (control positive, C+); (3) hypercholesterolemic + 3.5% protein from soybean tempeh; (4) hypercholesterolemic + 7% protein from soybean tempeh; (5) hypercholesterolemic + 3.5% protein from sweet lupine tempeh; (6) hypercholesterolemic + 7% protein from sweet lupine tempeh. All animal groups received the selected experimental diets for 4 weeks. Blood samples were drawn after the end of the experimental period. The evaluation of histopathological liver tissue sections and serum biochemical markers (aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol, triglycerides, lipoprotein fractions, urea nitrogen and uric acid) were conducted. The animal groups fed a hypercholesterolemic diet + 3.5% or 7% protein either from soybean or sweet lupine tempeh significantly (P<0.05) reduced the levels of total cholesterol (−37.41% to -48.43%), LDL-C (−57.51% to -75.35%), VLDL-C (−25.87% to -42.55%), triglycerides (−25.77% to -42.1%), AST (−10.19% to -37.15%), ALT (−23% to -45.86%), urea nitrogen (−9.38% to -19.04%) and uric acid (−9.04 to -14.27%), while HDL-C levels were increased (+57.67% to +76.09%) compared to that of the positive control group. The ratios of serum TC/HDL-C, LDL-C/HDL-C and AI were also decreased. On the other hand, the histopathological examination of the liver tissue sections of hypercholesterolemic rats fed a diet containing tempeh produced from soybean or sweet lupine revealed that the two types of tempeh reduced the degenerative changes. However, the higher levels of soybean and sweet lupine tempeh (7%) induced a better effect than the lower levels (3.5%), and were capable of recovering the damaged hepatocytes to almost their normal structure. These results indicated that tempeh obtained from soybean or sweet lupine, in particular, the high level (7%) significantly improved the levels of lipid profiles, activity of liver enzymes, concentrations of uric acid and urea nitrogen as well as induced a better protective effect in the hepatocytes, consequently, the two types of tempeh exhibited hypocholesterolemic, anti-atherogenic and hepatoprotective effects. Therefore, incorporating soybean or sweet lupine tempeh into the diet can be a possible coadjutor in the treatment and prevention of hypercholesterolemia.