Interaction of capsaicinoids with cell membrane models does not correlate with pungency of peppers.

Mixed monolayers were prepared using phospholipids in order to mimic cell membranes and fractions of capsaicinoids (extracted from Malagueta, Caps-M, and Bhut Jolokia, Caps-B, peppers). According to their surface-pressure isotherms and polarization-modulated infrared reflection absorption spectra (PM-IRRAS), weak molecular-level interactions were observed between Caps and phospholipids. Both Caps-M and Caps-B penetrated into the alkyl tail region of the monolayer, interacted with the phosphate group of the phospholipids and affected hydration of their C O groups. Since the physiological activity of Caps is not governed solely by interaction with cell membranes, it should require participation of a neuronal membrane receptor, e.g. vanilloid receptor (TRPV1). [ABSTRACT FROM AUTHOR]