Reduction of ochratoxin A toxicity in mice treated with phenylalanine and phenobarbital.

LD50 of ochratoxin A (OCT A) was estimated to be 29.4 mg/kg in intraperitoneal (i.p.) and 46.0 mg/kg in per os (p.o.) administration in ddY strain male mice. Acute toxicity of OCT A was reduced by simultaneous administration of phenylalanine or by pretreatment with phenobarbital (PB) for 1 week and the LD50 increased to 1.5-2.0 times control. Chromatographic analyses of OCT A and the metabolite, OCT alpha, extracted from urine and bile after administration of OCT A, indicated that amounts of OCT A and OCT alpha decreased in the urine and increased in the bile of PB-pretreated mice, suggesting that a change in metabolism of OCT A could cause the decrease in the toxicity of OCT A in PB-pretreated mice.