Thymol in cellular membrane models formed by negative charged lipids causes aggregation at the air-water interface

The physical-chemical effects of drugs/lipidic interfaces interactions are still little known, justifying investigations using model systems. Here, we investigated a drug with potential biological activity against microbial and tumorigenic cells, thymol, using phosphatidylserine as cellular membrane models. Surface pressure-area isotherms showed that selected amounts of thymol expand the monolayers and decreased its elasticity. Vibrational spectroscopy and Brewster angle microscopy pointed that thymol adsorbs on the lipid polar heads, affecting the aliphatic chain gauche conformations, causing aggregation at the interface. This indicated distinctive molecular accommodations of thymol along the phospholipidic structures, which is associated to its biological effect in natural membranes.