Objectives: We tested the hypothesis that liposomes could scavenge amphipathic bitter tastants, and that they could prevent their entry into cultured cells used as models of taste-bud cells.
Methods: Large unilamellar liposomes were prepared by hydrating a dry lipid film in artificial saliva buffer (ASB), and extruding the suspension through polycarbonate membranes of defined pore diameter. Phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and phosphatidylinositol were mixed in various formulations. Tastant partitioning into liposomes was evaluated by mixing the tastant and liposomes, dialyzing them against ASB and measuring the tastant by fluorescence spectroscopy. To measure the inhibition of tastant uptake by cells, liposomes and tastants were incubated with HSC-3 oral squamous cell carcinoma cells in T-25 flasks and the level of tastant in the medium was determined.
Results: For quinine, the order of efficacy for partitioning into liposomes was FormulationA>FormulationB=BMI-40>FormulationC, where BMI-40 is a proprietary compound. The order in preventing cell uptake was FormulationA>FormulationC>FormulationB>BMI-40. For cyclo(Leu-Trp) liposome partitioning was in the sequence FormulationB>FormulationA>BMI-40, and prevention of cellular uptake was in the order FormulationA>FormulationB>BMI-40.
Conclusions: Liposomes were more effective than BMI-40 in inhibiting the uptake of bitter tastants by cells. Therefore, liposomes could be used to minimize bitter tastant uptake by taste receptor cells.
Supported by the US-Israel BARD Fund and an AADR Student Research Fellowship.