Plant Science

Neuroexcitatory Starfruit

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Science  13 Dec 2013:
Vol. 342, Issue 6164, pp. 1292
DOI: 10.1126/science.342.6164.1292-a
CREDIT: SEDNEVAANNA/ISTOCK PHOTO

The starfruit (Averrhoa carambola), so named for the starlike shape generated when the fruit is cut in cross section, adds a tropical note to diverse diets. However, those with kidney failure have an unusual reaction to ingesting starfruit that includes hiccups, mental confusion, and seizures. Garcia-Cairasco et al., analyzing the response of kidney-damaged rats to starfruit extracts, have now identified the toxic element. The key compound is not the nephrotoxic oxalic acid, known to be present in the fruit, but rather is a molecule somewhat like phenylalanine, which the authors have named caramboxin. When injected into rat brains, caramboxin has a neuroexcitatory effect. Experiments with brain slices showed that caramboxin has properties of a glutamatergic receptor agonist. With this potent natural product, the starfruit may be useful for more than gracing a salad.

Angew. Chem. Int. Ed. 52, 10.1002/anie.201305382 (2013).

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