Surface activity of drugs: oximes of 3-formylrifamycin SV.

The surface activity of a series of oximes of 3-formylrifamycin SV, carrying an n-alkyl chain from C1 to C12 has been investigated. The oximes can be classified into two main groups, depending on the length of the chain and having different CMC, ageing effect and area/molecule values. Two different orientations of the rifamycin molecule at the surface are proposed for the two groups: the first one occurring in the oximes with ALKYL SUBstituents C1 to C3 and induced by the hydrophobic region located in the ansa of the base molecule, the second one occurring in the oximes with alkyl substitutents C1 to C12 and induced by the hydrophobic substituent itself. The oxime with the C8 chain is the most efficent surfactant of the series. Some biological implications are discussed for the inhibition of bacterial strains resistant to rifampicin and of viral RNA dependent DNA polymerases.