Hypoglycin A and B, two biologically active polypeptides from Blighia sapida

Abstract

Two peptides, hypoglycin A (a neutral compound, mp. 280-284[degree]; [[alpha]] 32/D] + 9.2 [plus or minus] 2[degree]) and hypoglycin B (an acid, double mp. 194-195[degree], 200-206[degree]; [[alpha]] 32/D + 9.6 [plus or minus] 2[degree]; neutralization equiv. 175) were isolated from the unripe seeds of Blighia sapida. The aqueous extract of the seeds, which contains some 14 ninhydrin-positive compounds in addition to hypoglycin A and B, was fractionated by means of the Amberlite ion-exchange resins IR-120,IRC-50 and IR-4B. The isolation of hypoglycin A and B was followed by toxicity tests using kittens and albino rats. The hypoglycaemlc activity of the peptides is circumstantial evidence of a connexion between the Jamaican disease "vomiting sickness" and the practice of eating the fruit of Blighia sapida. Hypoglycin A, but not hypoglycin B, occurs in the aril of the fruit, the unripe aril contains a very much higher concentration of hypoglycin A than the ripe aril.