17-Dehydrolimonoate A-ring lactone

While most of the limonoids of Citrus have been isolated from seeds, several occur in detectable amounts in other parts of the fruit. Minor amounts of deacetylnomilin, nomilin, obacunone, de-acetylnomilinic acid and nomilinic acid were identified in extracts of navel orange peel (37). 17-Dehydrolimonoate A-ring lactone was isolated from peel and juice of navel oranges (38) and nomilin has been reported to occur in grapefruit juice and juice vesicles (39). The only Citrus limonoids known to be bitter are limonin, VI, XII, obacunoic acid and IX (3). 

Hsu, A. C. Hasegawa, S. Maier, V. P. Bennett, R. D. 17-Dehydrolimonoate A-ring lactone, a possible metabolite of limonoate A-ring lactone in citrus fruits. Phytochem.,... 

Limonyl acetate Deoxylimonin Deoxylimonol 17-Dehydrolimonoate A-ring lactone... 

Limonin appears to be the predominant end product of the limonin pathway. However, some limonin is further metabolized to 17-dehydrolimonoate A-ring lactone (7), deoxylimonin (8), limonol (9) and other compounds (18-21). These metabolites are all nonbitter and only occur in seeds in low amounts. 

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