Background:

IC50: 10 nm against 100 nm capsaicin

The vanilloid TRPV1 receptor, also known as VR1 receptor, belongs to the large family of ‘transient receptor potential’ (TRP). TRPV1 functions as a molecular integrator of nociceptive stimuli, including heat, protons and plant toxins, and is most abundant in peripheral sensory fibers of the C and Ad type. 6-iodo-nordihydrocapsaicin is a potent TRPV1 antagonist.

In vitro: Using human recombinant TRPV1, 6-Iodonordihydrocapsaicin (IC50=10 nm against 100 nm capsaicin) was about four times more potent than the prototypical TRPV1 antagonist, capsazepine [1].

In vivo: 6-Iodonordihydrocapsaicin was tested against capsaicin also on native TRPV1 in: (i) rat dorsal root ganglion neurons in culture; (ii) guinea-pig urinary bladder; and (iii) guinea-pig bronchi. In all cases, except for the guineapig bronchi, the compound was significantly more potent than capsazepine as a TRPV1 antagonist [1].

Clinical trial: Up to now, 6-Iodonordihydrocapsaicin is still in the preclinical development stage.

Reference:
[1] Appendino G, Harrison S, De Petrocellis L, Daddario N, Bianchi F, Schiano Moriello A, Trevisani M, Benvenuti F, Geppetti P, Di Marzo V.  Halogenation of a capsaicin analogue leads to novel vanilloid TRPV1 receptor antagonists. Br J Pharmacol. 2003 Aug;139(8):1417-24.