Soy isoflavones reduce electronegative low-density lipoprotein (LDL(-)) and anti-LDL (-) autoantibodies in experimental atherosclerosis.
BACKGROUND
Isoflavones present in soybean may contribute to soy atheroprotective effects.


OBJECTIVE
To investigate the effect of soy isoflavones supplementation on the formation of electronegative LDL (LDL(-)) and its autoantibodies in blood plasma and aortic atheromas of rabbits fed an atherogenic casein-based diet enriched with isoflavones.


METHODS
New Zealand male rabbits (n = 15) were fed an atherogenic diet (27% casein) supplemented with isoflavones (0.73 or 7.3 mg of isoflavones/kg/day, Low and High Iso groups, respectively) for 180 days. Monthly, blood samples were collected after 12-15 h fasting and at 180 days of treatment all animals were sacrificed. Isoflavones were analyzed in plasma and urine samples by HPLC. LDL(-) in plasma and atheromas was detected by ELISA and immunohistochemistry, respectively, with a monoclonal antibody reactive to LDL(-). Autoantibodies reactive to LDL(-) were analyzed in plasma and aorta by ELISA.


RESULTS
Low and High Iso groups had decreased LDL-cholesterol, increased HDL-cholesterol and lower levels of LDL(-) in blood plasma and aortic atherosclerotic lesions than the non-supplemented Control group. IgG autoantibodies reactive to LDL(- )were higher in plasma of the Control group in comparison with the High and Low Iso groups. In contrast, the aortas from animals that consumed isoflavones showed higher levels of IgG reactive to LDL(- )than the Control group.


CONCLUSIONS
Soy isoflavones showed hypolipidemic effects and decreased the pro-inflammatory LDL(-) subfraction in blood plasma and aorta of hypercholesterolemic rabbits.
Teixeira Damasceno
Nágila Raquel
NR
Department of Nutrition, School of Public Health, São Paulo, SP, Brasil.
Apolinário
Elaine
E
Dias Flauzino
Fabiana
F
Fernandes
Irene
I
Abdalla
Dulcineia Saes Parra
DS
D000818:Animals; D001011:Aorta / Q000737:chemistry; D050197:Atherosclerosis / Q000178:diet therapy*; D001323:Autoantibodies / Q000032:analysis*; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D004036:Diet, Atherogenic; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D007074:Immunoglobulin G / Q000032:analysis; D007150:Immunohistochemistry; D007529:Isoflavones / Q000008:administration & dosage* / Q000097:blood / Q000652:urine; D008297:Male; D011817:Rabbits; D013025:Glycine max / Q000737:chemistry*
D001323:Autoantibodies; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007074:Immunoglobulin G; D007529:Isoflavones