Reduction of aflatoxins B1 and B2 with sodium borohydride

Reduction of aflatoxin B1 and aflatoxin B2 with sodium borohydride quantitatively yielded new fluorescent derivatives, designated as aflatoxin RB1 and aflatoxin RB2. Mass spectrometric data showed that RB1 and RB2 were trihydroxy derivatives of B1 and B2, respectively. Nuclear magnetic resonance analysis revealed that new chemical shifts were present in aflatoxins RB1 and RB2 in addition to those of the parent aflatoxins. The new compounds had lower melting points and different ultraviolet and infrared spectra compared to aflatoxins B1 and B2 and the monohydroxy derivative aflatoxicol. They were lses toxic to chick embryos than the parent toxins. Since the reduction yields were quantitative and since the reduction products could be detected at low levels comparable to those for B1 and B2, the reduction reaction could be used as a confirmatory test for both aflatoxins B1 and B2. Preliminary results obtained from gas-liquid chromatography (GLC) analysis of the trimethylsilyl derivatives of aflatoxins RB1 and RB2 indicated that these compounds could furnish the basis for developing an analytical GLC method for aflatoxins B1 and B2.