[Spectrophotometric research on the photochemical isomerization of the polyene macrolide antibiotic levorin A2]. / Spektrofotometricheskoe issledovanie fotokhimicheskoi izomerizatsii polienovogo makrolidnogo antibiotika levorin A2.

Photochemical (cis-trans) isomerization of levorin A2 under the effect of light at wave lengths of 313 and 365 nm (excitation of the polyenic system and p-aminobenzoylene respectively) was studied. In case of the polyenic system excitation the reaction was reversible and the process quantum yield was extremely low while the use of light at the wave length of 313 nm as photochemical activator resulted in increasing the quantum yield by two orders. In this case triplet-triplet transfer of energy took place. A calculation procedure is recommended for quantitative determination of the quantum yield of levorin isomerization including direct and reverse reactions. The procedure may be used in study of other objects with similar mechanisms of phototransformation.

[Physiochemical characteristics of 3 states of the nystatin molecule]. / Fiziko-khimicheskie osobennosti trekh sostoianii molekuly nistatina.

Conditions for production of nystation in three main states, i.e. inert, native and activated were determined. It was found that nystatin used in medical practice is in the inert state which is most stable for this antibiotic. Under certain conditions this state is transferred into the native or activated state. Solid forms can be prepared. The native and activated states are significantly less stable. The physicochemical characteristics of these nystatin states are presented. The data obtained can be used for the development of effective methods for nystatin production and purification.