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IUPAC name
Systematic IUPAC name
2-[(2S)-2-amino-2-carboxyethyl]-6-hydroxy-4-methoxybenzoic acid
3D model (JSmol)
Molar mass 255.226 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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 AMPA glutamatergic ionotropic receptors with potent excitatory, convulsant, and neurodegenerative properties.[2]

Due to a possible interaction between caramboxin and oxalic acid in starfruit leading to both neurotoxic and nephrotoxic effects, eating starfruit or drinking its juice on an empty stomach is not recommended, even for individuals with normal kidney function.[4]


  1. ^ "Star fruit's chemical curse". Chemical & Engineering News: 28. December 2, 2013.
  2. ^ a b Garcia-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. doi:10.1002/anie.201305382. PMID 24281890.
  3. ^ Caetano, Camille Pereira; De Sá, Cinara Barros; Faleiros, Bruno Antônio Paixão; Gomes, Marcelo Fonseca Coutinho Fernandes; Pereira, Edna Regina Silva (2017). "Neurotoxicity following the Ingestion of Bilimbi Fruit (Averrhoa bilimbi) in an End-Stage Renal Disease Patient on Hemodialysis". Case Reports in Nephrology and Dialysis. 7 (1): 6–12. doi:10.1159/000454945. PMC 5301110. PMID 28203564.
  4. ^ Neto, M. M; Silva, G. E; Costa, R. S; Vieira Neto, O. M; Garcia-Cairasco, N; Lopes, N. P; Haendchen, P. F; Silveira, C; Mendes, A. R; Filho, R. R; Dantas, M (2009). "Star fruit: Simultaneous neurotoxic and nephrotoxic effects in people with previously normal renal function". Clinical Kidney Journal. 2 (6): 485–488. doi:10.1093/ndtplus/sfp108. PMC 4421323.