Optical rotary dispersion of some heptaene antibiotics

Experimental differences in the curves of the optic rotation dispersion (ORD) of cystrans-heptaenic antibiotics were found. The ORD curves of amphotericin B, mycoheptin, levorin components and isolevorin A2, components of criptomycin and candidin were registered. The curves of the ORD which were smooth had been prepared in dimethylsulphoxide in the spectral range at 450 to 600 nm. In the spectral range at 300 to 420 nm the ORD curves appeared to be anomal with a complex Kotton effect, they were prepared in methyl alcohol. The Kotton effect was probably due to asymmetry of the electron membranes of polyenic chromophore induced by the other part of the polyen molecule. This was evident from the fact that the curve of the Kotton effect was situated in the same spectral range as the absorption bond of the polyenic chromophore. The oscillating structure in the absorption spectrum and the curve of the complex Kotton effect were analogous.