The other side of the moon: bitter taste receptors activated by vanillin and capsaicin

Vanilla and chilli pepper are widely used in food preparation worldwide for their sensory properties, mainly related to the fragrance (odorant properties) of vanillin the first and the chemestetic properties of capsaicin the second. Both vanillin and capsaicin are also known for their capability to elicit bitterness as a secondary sensory sensation (1,2), but which T2Rs receptors are involved has never been reported. In our work we transfected all human bitter taste receptors into a heterologous cell-based assay system and screened for activation by vanillin and capsaicin. Both compounds were first tested at one concentration based on the maximum concentration tolerated by the assay. Positive receptor-compound combinations were retested in a full concentration-response experiment where the compound was tested at eight concentrations. We identified TAS2R20 to be the principle detector of vanillin as no other TAS2R responded to this compound. On the other hand, capsaicin activated three TAS2Rs, namely TAS2R13, TAS2R14 and TAS2R39.