Evidence that soyasaponin Bb retards disease progression in a murine model of polycystic kidney disease.
BACKGROUND
We reported a lessened cyst growth in the pcy mouse model of polycystic kidney disease (PKD) when mice were fed a soy protein isolate (SPI)-based diet and hypothesized that the soyasaponins may be associated with this therapeutic effect. The effects of feeding a saponin-enriched alcohol extract (SEAE) from SPI, an isoflavone- and saponin-enriched soy supplement (Novasoy 400), or a 99.5% pure soyasaponin Bb powder on cyst growth are reported here.


METHODS
The therapeutic effects of the soyasaponins were studied in 60-day-old male pcy mice in two separate, 90-day feeding trials. In the first study, mice were fed either a casein-based (control) diet, a diet in which SPI replaced the casein or the control diet supplemented with SEAE. In the second study, mice were fed the control diet unsupplemented or supplemented with either a soyasaponin- and isoflavone-enriched soy product (Novasoy 400) or a 99.5% pure soyasaponin Bb powder.


RESULTS
In study 1, kidney weight, water content, and plasma creatinine and urea levels were markedly reduced in the SEAE-fed animals compared to tissues from the control group; likewise, mice fed the SPI-based diet showed a decreased plasma creatinine, but only a slightly reduced plasma urea. In study 2, kidney weight, water content, plasma creatinine and urea levels were significantly reduced in mice fed the soyasaponin Bb powder and the Novasoy-400 supplement, compared to controls.


CONCLUSIONS
Soyasaponin Bb can impede kidney enlargement and cyst growth in the pcy mouse model of PKD. Further studies are needed to determine its most effective dose and mechanism of action.
Philbrick
Diana J
DJ
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
Bureau
Dominique P
DP
Collins
F William
FW
Holub
Bruce J
BJ
D000821:Animal Feed; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002364:Caseins / Q000494:pharmacology; D019587:Dietary Supplements; D004195:Disease Models, Animal; D007529:Isoflavones / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009929:Organ Size / Q000187:drug effects; D007690:Polycystic Kidney Diseases / Q000188:drug therapy* / Q000473:pathology; D012503:Saponins / Q000737:chemistry / Q000494:pharmacology*; D030262:Soybean Proteins / Q000737:chemistry / Q000494:pharmacology*; D014867:Water / Q000378:metabolism
D002364:Caseins; D007529:Isoflavones; D012503:Saponins; D030262:Soybean Proteins; C000602851:soyasaponin Bb; D014867:Water