[Dye-sensitized photoisomerization of polyenic macrolide antibiotics]

Photoisomerization of levorin A2, a polyenic macrolide, sensitized by various dyes such as thiazines, acridines, xanthenes and phthalocyanines was studied. The use of the dyes made it possible to shift the isomerization process to the visible spectrum region and to increase the quantum yield to 1. The conditions of the triplet-triplet transfer of the sensitized reaction energy were investigated. By its physio-chemical and biological properties the levorin A2 isomer was identical to the levorin A2 isomer resulting from the direct action on the heptaene chromophore. The dye efficiency was demonstrated in regard to other heptaene antibiotics such as trichomycin and candicidin.