Fractionation of aurintricarboxylic acid and effects of its components on nuclear swelling and nucleic acid synthesis.

Crude aurintricarboxylic acid synthesized by the conventional method was fractionated into 8 components (A1-A8) by silica gel thin layer chromatography. Some of the components were isolated and their effects were tested on nuclear swelling and on in vitro RNA synthesis and DNA synthesis using isolated polymerases. Only two components with low RF (A7 and A8) induced strong nuclear swelling. The other components were almost inactive. Formaurin-dicarboxylic acid, a contaminating polyanion of crude aurintricarboxylic acid, was synthesized separately. It was as effective as the two active components in nuclear swelling and inhibited RNA and DNA polymerases on naked DNA template. However, it stimulated RNA synthesis on chromatin template probably by dissociating histones from DNA. Unfractionated aurintricarboxylic acid showed the same effects at higher concentrations. A preliminary analysis indicated one of the inactive components (A4) is genuine aurintricarboxylic acid. The results suggest that the observed activity of crude aurintricarboxylic acid is due to some contaminating substances, one of which is formaurindicarboxylic acid.