Liposomes inhbit uptake of bitter tastants into cultured epithelial cells

ORCiD

Nejat Düzgüneş: 0000-0001-6159-1391

Department

Biomedical Sciences

Document Type

Conference Presentation

Conference Title

85th General Session of the International Association for Dental Research (IADR) and 36rd Annual Meeting of the American Association for Dental Research (AADR)

Location

New Orleans, LA

Conference Dates

March 21-24, 2007

Date of Presentation

3-22-2007

Journal Title

Journal of Dental Research

Journal ISSN

0022-0345

Journal Volume Number

86 (Special issue A)

First Page

569

Abstract

Instinctive rejection of bitter taste by mammals is a phylogenetically developed mechanism for survival. Amphipathic bitter tastants permeate into taste cells through the apical taste-bud pores and stimulate multiple receptors and signaling pathways to produce the bitter sensation. Diets including the bitter foods, flavonoids and terpenes, have been linked to lower rates of cancer and coronary heart disease. Bitter tastants are also produced during the processing of certain foods, and reduce their acceptance. It would be useful to find healthier alternatives than sugar to inhibit the lingering bitter aftertaste. 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.

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