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Star fruit (also spelled starfruit) is the star shaped fruit of Averrhoa carambola. Averrhoa carambola is a tree that is native to the Philippines, Indonesia, Malaysia, India, Bangladesh and Sri Lanka. Star fruit is also known as starfruit and carambola.
Antioxidants Found in Juice
Star fruit juice is a very good source of natural antioxidants. Star fruit was found to contain a good quantity of L-ascorbic acid, (+)-catechin, (-)-epicatechin and gallic acid (in the form of gallotannins).[2][5]
(-)-Epicatechin and (+)-catechin are moderate inhibitors of MAO-B enzymes.
(-)-Epicatechin is a potent inhibitor of SULT1A1.
(+)-Catechin is a potent inhibitor of SULT1A3 and an inhibitor of P-Glycoprotein.
Gallic acid induces Estradiol 17beta-dehydrogenase oxidation by 30%.[7] It induces SULT1A1 and SULT1A3.[8] It also inhibits xanthine oxidase and aldehyde dehydrogenase.
Volatile Compounds in Juice
The major volatile components of star fruit were butyl acetate, ethyl decanoate, hexadecanoic acid, l-Phenyl dodecane, l-Phenyl undecane, and cyclohexyl octadecanal.[5]
Amino Acids in Star Fruit
Star fruit was found to contain several amino acids including
glycine, L-alanine, L-serine, L-aspartic acid, L-glutamic acid, L-valine, and proline.[5]
Vitamins in Star Fruit
Star fruit was found to contain L-ascorbic acid (vitamin C) at 28 mg/100 g, and and beta-carotene (a precursor to vitamin A) at 623 μg/100 g. Other vitamins found were thiamine (vitamin B1), niacin (vitamin B3), and riboflavin (vitamin B2).[5]
Vitamin E (α-tocopherol) and vitamin D could not be detected in star fruit.[5]
Acids in Star Fruit
Star fruit contains citric acid, tartaric acid, succinic acid, fumaric acid, oxalic acid, α-ketoglutaric and, and malic acid.[5]
Minerals in Star Fruit
The major minerals in start fruit were found to be potassium 222 mg/100 g) and calcium (41 mg/100 g).[5]
Effects on the Cytochrome P450 Enzyme System
Effects In Humans In Vivo
No human tests have been found. If a test exists please leave us a note about it by using the DISCUSS link at the bottom of this page.
Effects In Rats In Vivo
The metabolism of carbamazepine, a known substrate of CYP3A4, was inhibited by star fruit in rats, indicating that starfruit is a CYP3A4 inhibitor. The inhibition by star fruit juice was recovered within approximately 24 hours. Inhibition appeared to be enteric and not in the liver.[1]
Effects on Alanine Aminotransferase (ALT) in Rats
Star fruit juice prepared and stored for 3 hours and given to rats caused a 38% increase in alanine aminotransferase (ALT, also known as EC 2.6.1.2). However fresh juice or juice stored for 1 hour had no detectable effect on ALT. Despite higher levels of ALT, no other effects on the liver were identified, and the juice showed no evidence of toxicity in the rats tested. The rats behaved normally and did not show any sign of intoxication.[6]
Elevated levels of ALT are sometimes interpreted as possible signs of liver toxicity. However, elevated levels of ALT do not automatically mean there is liver toxicity. In humans fluctuation of ALT levels is normal over the course of the day, and ALT levels can also increase in response to strenuous physical exercise.
Potentially Fatal Reactions In Individuals With Renal failure
Star fruit juice should be avoided by individuals suffering from renal failure. Star fruit juice ingestion has been fatal in individuals suffering from renal failure.[3][4]