pH‐Dependent Interaction of Four Different Bile Salts with POPG Liposomes Studied by Dynamic Light Scattering and Second Harmonic Spectroscopy

다국어 초록 (Multilingual Abstract)

In recent years the role of bile salts in colorectal cancer has been gaining importance. In addition, it has been observed that for diseases associated with gastrointestinal tract, the pH becomes slightly acidic. In this report we have investigated the pH dependent bile acid – bile salt transformation on the integrity and permeability of phosphatidyl glycerol (POPG) liposomes by dynamic light scattering and interfacial second harmonic generation spectroscopy. Using four different bile salts whose chemical properties vary widely we have observed that in their neutral form (i.e bile acids) they are able to alter the POPG membrane properties significantly higher compared to their ionic (i. e. bile salts) form. Our results indicate that out of the four bile salts, Sodium Deoxycholate and Sodium Cholate have the potential to damage membranes in the colon as their pKa is closer to the pH measured in the gastrointestinal tract. Therefore, one of the pathways of bile salt induced cytotoxicity in the gastrointestinal tract, may occur due to the potential membrane damaging action of these bile salts at acidic pH.
The bile acid – bile salt transformation on the permeability and integrity of L‐α‐phosphatidyl DL‐glycerol (POPG) liposomes have been investigated by the interfacial selective second harmonic (SH) spectroscopy and dynamic light scattering experiments respectively. Our results indicate that when bile molecules are present in membrane as neutral form they have much superior potential to alter the POPG membrane properties.