Evaluation of steroidal amines as lipid raft modulators and potential anti-influenza agents

The influenza A virus (IFV) possesses a highly ordered cholesterol-rich lipid envelope. A specific composition and structure of this membrane raft envelope are essential for viral entry into cells and virus budding. Several steroidal amines were investigated for antiviral activity against IFV. Both, a positively charged amino function and the highly hydrophobic (ClogP≥5.9) ring system are required for IC50 values in the low μM range. An amino substituent is preferential to an azacyclic A-ring. We showed that these compounds either disrupt or augment membrane rafts and in some cases inactivate the free virus. Some of the compounds also interfere with virus budding. The antiviral selectivity improved in the series 3-amino, 3-aminomethyl, 3-aminoethyl, or by introducing an OH function in the A-ring. Steroidal amines show a new mode of antiviral action in directly targeting the virus envelope and its biological functions.

Inhibition of (+)-aristolochene synthase with iminium salts resembling eudesmane cation

Trigonal iminium halides of (4aS,7S)-1,4a-dimethyl- and (4aS,7S)-4a-methyl-7-(prop-1-en-2-yl)-2,3,4,4a,5,6,7,8-octahydroquinolinium ions, aimed to mimic transition states associated with the aristolochene synthase-catalyzed cyclization of (-)-germacrene A to eudesmane cation, were evaluated under standard kinetic steady-state conditions. In the presence of inorganic diphosphate, these analogues were shown to competitively inhibit the enzyme, suggesting a stabilizing role for the diphosphate leaving group in this apparently endothermic transformation.