Seed extracts of Casimiroa edulis Llave et Lex have yielded 5-methoxy-8-geranyloxypsoralen, phellopterin, zapotin, 2',6,6-trimethoxyflavone, 3',5,6-trimethoxyflavone, 3',5,5',6-tetramethoxyflavone, casimiroin, eduline, edulein, 1-methyl-2-phenyl-4-quinolone, zapoterin, 7a-obacunol, and deacetylnomilin. Zapoterin is a C26 limonoid and has been converted into a monoacetate and oxidized to a ketone, zapoterone, with chromic acid. These chemical transformations and spectroscopic considerations indicate that zapoterin is 12a-hydroxyobacunone. The synthesis of 3',5,6-trimethoxy- and 3',5,5',6-tetramethoxyflavone is also reported.