Adipose tissue has been implicated as the primary site of nitrosopyriolidine (NPYR) production in fried bacon. In a study on the precursors of NPYR, pork belly adipose tissue was extracted with CHCI3/MeOH and yielded an organic layer, an aqueous polar fraction, and a tissue residue. Fractions were heated with nitrite, and the polar fraction accounted for most of the nitrosamines in intact adipose tissue. Fractionation of the polar fraction yielded an eluate that was collected in seven aliquots. All aliquots formed N‐nitro‐sodimethylamine when heated with nitrite, but the bulk of NPYR was formed from an eluate corresponding to the first of three UV absorbent bands at 254 nm.

with 60% (fresh weight basis) water. The seeded rice culture medium was kept for 7 days at 25 °C and 30 days at 12 °C. At the end of this period, the cultures were dried and ground to a fine mesh.The dry culture (2.5 kg) was moistened with 30% water (20 mL of water/100 g of dry cultures); about 3 L of ethyl acetate was added to this moistened culture and kept at 5 °C for 24 h and filtered. The residue was once more extracted with 2 L of fresh ethyl acetate. The combined ethyl acetate was concentrated to a gum, which was redissolved in 600 mL of acetonitrile and partitioned against 600 mL of petroleum ether (bp 60-70 °C); the petroleum ether was discarded. The acetonitrile layer was concentrated and chromatographed on 800 g of silica gel (Davison 923, 100 mesh, activated at least 1 h at 110 °C, slurry packed in dichloromethane, eluting solvent: 20% ethyl acetate in dichloromethane -* 100% ethyl acetate). The fractions were collected in 300-mL portions and were examined for zearalenone and its derivatives by TLC (Jackson et al., 1976). The fractions eluted with 2 L of 20% ethyl acetate contained mainly zearalenone. The fractions eluted with 3 L of ethyl acetate were enriched in F-5-4 and F-5-3 and those eluted with 3 L of 100% ethyl acetate had highly polar fluorescent components besides F-5-4 and F-5-3.The fraction enriched in F-5-4 and F-5-3 was chromatographed on five preparative TLC plates developed three times in chloroform-absolute ethanol (97:3). The bands corresponding to F-5-4 and F-5-3 were removed and eluted with acetone; these components were successively rechromatographed on TLC to give 40 mg of F-5-4 (mp 168-168.5 °C) and 30 mg F-5-3 (mp 201-202 °C). Both compounds were identical with the authentic samples as determined by TLC, GC/MS, UV, and mass spectra.The fraction containing components more polar than F-5-3 were chromatographed on four preparative TLC plates and were developed four times in chloroform-absolute ethanol (97:3). A fluorescent band which appeared just below F-5-3 was eluted with acetone; the evaporation of acetone gave approximately 40 mg of a yellow viscous residue. This residue was rechromatographed on preparative TLC plate to give approximately 15 mg of the material, which had NMR and UV spectrum similar to zearalenone. This material was further purified by TLC to yield 6 mg of pure sample. A 13C NMR spectrum obtained on this compound was similar to that of F-5-3 and F-5-4. The compound was further resolved into two components at Rf 0.28 and 0.33, which were designated as F-5-1 (<1 mg) and F-5-2 (<2 mg: mp 168-169.5 °C). Anal.