Biological activity of aflatoxin B2a.

The toxicity of alfatoxin B(2a) (hydroxydihydro-aflatoxin B(1)) was studied in several biological systems. Aflatoxin B(2a) is the monohydroxylated derivative obtained from addition of water to the double bond of the terminal furan of B(1). Examination of the sensitivity of a group of microorganisms to B(2a) demonstrated that the inhibitory spectrum was similar to aflatoxin B(1). However, the toxicity of B(2a) was markedly lower than B(1), as measured by the initiation of bile duct hyperplasia in ducklings. Binding of aflatoxin to deoxyribonucleic acid (DNA) was determined by measuring the hypochromicity produced by the nucleic acid at 363 nm and the capacity of increasing amounts of DNA to quench the fluorescence of the toxin was also used as a measure of the binding of toxin to nucleic acid. These tests showed that the DNA-binding capacity of B(2a) was lower than B(1).