Caramboxin (CBX) is a
toxin found in
star fruit (Averrhoa carambola).[1][2] Individuals with some types of
kidney disease are susceptible to adverse neurological effects including intoxication,
seizures and even death after eating star fruit.[3] Caramboxin has been identified as the
neurotoxin responsible for these effects. Caramboxin is a
non-proteinogenic amino acid that stimulates the
glutamate receptors in neurons. Its chemical structure is similar to the amino acid
phenylalanine. Caramboxin is an agonist of both
NMDA and
AMPAglutamatergic ionotropic receptors with potent excitatory, convulsant, and neurodegenerative properties.[2]
A possible interaction between caramboxin and
oxalic acid in starfruit can lead to both neurotoxic and nephrotoxic effects. Consuming large amounts of starfruit or its juice on an empty stomach is not recommended, even for individuals with normal kidney function.[4]
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abGarcia-Cairasco, Norberto; Moyses-Neto, Miguel; Del Vecchio, Flavio; Oliveira, José A. C; Dos Santos, Francisco L; Castro, Olagide W; Arisi, Gabriel M; Dantas, Márcio; Carolino, Ruither O. G; Coutinho-Netto, Joaquim; Dagostin, Andre L. A; Rodrigues, Marcelo C. A; Leão, Ricardo M; Quintiliano, Samir A. P; Silva, Luiz F; Gobbo-Neto, Leonardo; Lopes, Norberto P (2013). "Elucidating the Neurotoxicity of the Star Fruit". Angewandte Chemie International Edition. 52 (49): 13067–70.
doi:
10.1002/anie.201305382.
PMID24281890.