Modulation of non steroidal anti-inflammatory drug induced membrane fusion by copper coordination of these drugs: anchoring effect.

Membrane fusion, an integral event in several biological processes, is characterized by several intermediate steps guided by specific energy barriers. Hence, it requires the aid of fusogens to complete the process. Common fusogens, such as proteins/peptides, have the ability to overcome theses barriers by their conformational reorganization, an advantage not shared by small drug molecules. Hence, drug induced fusion at physiologically relevant drug concentrations is rare and occurs only in the case of the oxicam group of non steroidal anti-inflammatory drugs (NSAIDs). To use drugs to induce and control membrane fusion in various biochemical processes requires the understanding of how different parameters modulate fusion. Also, fusion efficacy needs to be enhanced. Here we have synthesized and used Cu(II) complexes of fusogenic oxicam NSAIDs, Meloxicam and Piroxicam, to induce fusion in model membranes monitored by using DSC, TEM, steady-state, and time-resolved spectroscopy. The ability of the complexes to anchor apposing model membranes to initiate/facilitate fusion has been demonstrated. This results in better fusion efficacy compared to the bare drugs. These complexes can take the fusion to its final step. Unlike other designed membrane anchors, the role of molecular recognition and strength of interaction between molecular partners is obliterated for these preformed Cu(II)-NSAIDs.