spilanthol

Spilanthol is an unsaturated alkylamide (a class of compounds derived from fatty acids) abundant in Acmella oleracea, a member of the Asteraceae family. There is no record in this database of this compound itself being a bitter taste component; rather, what is tracked is a distinct oral sensation separate from bitterness: a tingling, pungent, or numbing sensation in the mouth. When whole flower buds are placed in the mouth, an initial grassy flavor is recorded, followed by an intense numbing sensation, excessive salivation, and a cooling effect in the throat.

In an experiment using isolated taste receptor cells (TBCs) from mice, spilanthol was shown to enhance responses to sodium chloride (NaCl). When 1222 isolated taste cells were presented with NaCl and KCl and their responses measured by calcium imaging, 72.8% (134 of 184 cells) of the NaCl-responsive cells showed greater magnitude responses to a mixture of NaCl and spilanthol than to NaCl alone. Responses to 140 millimolar NaCl were significantly enhanced by 3 micromolar spilanthol, and the enhancement was concentrated in Type III cells. Enhancement in trigeminal neurons was minimal, and was significant only when 200 millimolar NaCl and 6 micromolar spilanthol were combined.

Tingling, pungency, and numbing are recorded as distinct sensations attributed by review articles to spilanthol and structurally related alkylamides. However, these descriptions appear only in the literature review section at the introduction of the studies, not in the experimental results. The experiments themselves, using taste receptor cells or trigeminal neurons, did not measure the tingling or numbing sensations felt in the human mouth. For saltiness enhancement as well, evidence in humans is limited to preliminary, unpublished observations using split-tongue methods, and the records caution against inferring human effects from these experimental results.

In reviews of Acmella oleracea research, spilanthol is positioned alongside other alkylamides as a central component in the botanical literature, and Thailand's Mahidol University plant information page lists it as a constituent of the same species. However, content varies greatly by plant part, geographic source, and extraction method, and a value of 16.50 milligrams per gram of dry weight has been reported for flower extracts. This content measurement is limited to summary-level confirmation, and the full text of a primary quantitative study supporting differences in content between plant parts has not yet been appended.