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Chemistry In Pictures

Chemistry in Pictures: Behind the scorpion’s glow

by Craig Bettenhausen
April 3, 2020


Left to right, under UV light, a freshly molted scorpion glows faintly, brighter at its joints. An emtpy exeoskeleton glows bright blue, and a scorpion almost ready to molt glows moderately.
Credit: Masahiro Miyashita/J. Nat. Prod.
A carbohydrate macrocycle.

Why do most scorpions fluoresce under a blacklight? Evolutionarily, we’re not sure. But chemically, Masahiro Miyashita is on case. These photos, lit with a UV lamp, from Miyashita show a live scorpion almost ready to molt, a cast-off exoskeleton (cuticle), and a scorpion just after molting (right to left). “To date, two compounds, β-carboline and 7-hydroxy-4-methylcoumarin, have been identified as fluorescent components in the scorpion cuticle,” he says. But those were just the ones extractable with ethanol or methanol. Miyashita found a new one (structure shown) that’s soluble in nonpolar solvents such as hexane. The compound shows anti-protozoa and antifungal activity in yellow pansies and earthworms, respectively, so the scorpions may be making it to fight off infection. Aesthetic benefits might be just a bonus.

Credit: Masahiro Miyashita/J. Nat. Prod. 2020, DOI: 10.1021/acs.jnatprod.9b00972

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