The Interaction of the Brominated Flame Retardant: Tetrabromobisphenol A with Phospholipid Membranes

Tetrabromobisphenol A (TBBPA) is one of the most widely used members of the family of brominated flame retardants (BFRs). BFRs, including TBBPA have been shown to be widely distributed within the environment and there is growing evidence of their bio-accumulation within animals and man. Toxicological studies have shown that TBBPA can be harmful to cells by modulating a number of cell signalling processes. In this study, we employed fluorescence spectroscopy and differential scanning calorimetry to investigate the interaction of TBBPA with phospholipid membranes, as this is the most likely route for it to influence membrane-associated cellular processes. TBBPA readily and randomly partitions throughout all regions of the phospholipid bilayer with high efficacy [partition coefficient (Log K(p))=5.7+/-0.7]. A decrease in membrane fluidity in both liquid-crystalline and gel-phase membranes was detected at concentrations of TBBPA as low as 2.5 microM. TBBPA also decreases the phase transition temperature of dipalmitoyl phoshatidylcholine (DPPC) membranes and broadened transition peaks, in a fashion similar to that for cholesterol. TBBPA, however, also prefers to partition into membrane regions not too highly enriched with cholesterol. Our findings therefore suggests that, the toxic effects of TBBPA, may at least in part, be due to its lipid membrane binding/perturbing effects, which in turn, could influence biological processes involving cell membranes.