In the Scoville scale, what is the hottest chemical?

The story behind the answer

Resiniferatoxin is correct because it’s an ultra-potent analog of capsaicin that activates the same TRPV1 “chili pepper” pain receptors but far more strongly—estimated to be hundreds to a thousand times hotter than capsaicin, placing it in the billions of Scoville Heat Units. It occurs naturally in the Moroccan plant Euphorbia resinifera. By comparison, capsaicin and dihydrocapsaicin top out around 16 million SHU, and tinyatoxin, while very hot, is still below resiniferatoxin.

Context tip: The Scoville scale originally relied on human taste tests and now correlates with chemical analysis of capsaicinoids. Memory hook: “Resin-‘inferno’-toxin”—think resin that brings an inferno—signals the most blistering burn. Interestingly, because it powerfully targets TRPV1, resiniferatoxin is being studied to selectively silence pain fibers in severe chronic pain.