Extraoral Taste Receptor Discovery: New Light on Ayurvedic Pharmacology

Table 4

Transducers involved in thermosensation and examples of agonists ( information Ayurveda versus modern science: evergreen tree and Andrographis paniculata are described as being “cold” in Ayurveda [119] and clove is described as being “hot” in Ayurveda [119], while eugenol was found to have hypothermic effects [120]; mint is pungent and therefore “hot” although it induces a cooling sensation [119]).

TRP channels	Agonists
Cooling Sensation
TRPM5 (sweet, umami, bitter taste receptor cells) (15°–35°C) [121]	Rutamarin (rue) [122]
TRPM8 (trigeminal orosensation); Moderate non-painful coolness (10°–28°C) [123, 124]	Menthol [123]; Geraniol (rose oil, citronella oil) [125]; Eucalyptol (eucalyptus) [125]
TRPA1 (trigeminal orosensation); Noxious cold or painful cold; (<15°C) [126, 127]	Eugenol (clove) [128]; See also TRPA1 (pungency) under Warming sensation
Warming sensation
TRPV4 (trigeminal orosensation); (>27°C) non painful warmth [129]	Bisandrographolide A (Andrographis paniculata) [130]; Eugenol [131]
TRPV3 (trigeminal orosensation) (≥33°C) non painful warmth [132]	Carvacrol (oregano) [133]; Eugenol [133]; Thymol (thyme) [133]; Camphor [134]
TRPV1 (trigeminal orosensation) (>43°C) painful heat [135], pungency	Capsaicin (chili peppers) [136]; Piperine (black pepper) [137]; Low pH (<5.9) [138] (sour items?)
TRPV2 (trigeminal orosensation); (>52°C) extreme heat [135]	Δ9-Tetrahydrocannabinol, Δ9-tetrahydrocannabinol acid [139], cannabidiol (marijuana) [140]
TRPA1 (trigeminal orosensation – pungency, burning sensation)	Allicin (garlic) [141]; 6-Gingerol, zingerone, 6-shogaol (ginger) [142]; Allyl isothiocyanate (horseradish, mustard oil) [143]; Cinnamaldehyde (cinnamon) [144]; Oleocanthal (olive oil) [145]; Organic weak acids [146] (sour plants?); Polygodial (water pepper) [147]; Perillaketone, perillaldehyde (Perilla frutescens) [148]