THE EFFECTS OF DIETARY SUPPLEMENTATION WITH YUCCA-SCHIDIGERA EXTRACT OR FRACTIONS THEREOF ON NITROGEN-METABOLISM AND GASTROINTESTINAL FERMENTATION PROCESSES IN THE RAT

Yucca schidigera was fractionated with butan-1-ol, yielding a butanol- extractable (BE) fraction, containing all the in vitro antimicrobial a ctivity, and the aqueous, non-butanol-extractable (NBE) fraction. Four groups of five female rats (12 weeks old) were allowed ad libitum acc ess to diets supplemented with water (control) or 200 mfi kg(-1) total Y schidigera (TOT) or its fraction equivalent of NBE or BE for 64 day s. The effects of the fractions and their interactions in the TOT trea tment were analysed according to the factorial experimental structure by two-way ANOVA. NBE reduced serum urea (-50%, P = 0.019) and ammonia (-46%, P = 0.037) concentrations, serum/urine concentration quotients of urea (-79%, P = 0.009) and ammonia (-57%, P = 0.002). NBE also red uced hindgut acetate/propionate (-12%, P = 0.007) but increased faecal ammonia concentration (+87%, P=0.039). BE reduced hindgut indoles (-2 5%, P = 0.023) and interacted synergystically with NBE in the TOT trea tment to further reduce hindgut acetate/propionate by 6% (P = 0.006). NBE increased (+27%, P = 0.002) and BE decreased (-57%, P = 0.005) hin dgut urease activity levels, resulting in essentially no change (+ 4%) in the TOT treatment. The in vitro antimicrobial activity of Y schidi gera is an unlikely explanation for most of its effects in vivo becaus e these are caused by NBE and in vitro antimicrobial activity is exclu sive to BE. Sarsasapogenin and smilagenin were also exclusive (> 98%) to BE and cannot account for the effects of Y schidigera on N metaboli sm. (C) 1998 SCI.