Conversion of intravenously administered beta-cryptoxanthin to a beta-carotene-like compound in mouse lung

The intravenous administration of beta-cryptoxanthin (320 microg/mouse) into 4-wk-old ddY mice caused a new peak in addition to the peak of beta-cryptoxanthin during high-performance liquid chromatography (HPLC) of the lipid fraction of lung homogenate. Different HPLC conditions revealed that the new peak might be attributed to a beta-carotene-like compound. The average retention times for the new peak and authentic all-trans-beta-carotene were 14.97 and 15.00 min, respectively, in a HPLC system using a YMC-Pack ODS-A column and methanol-based mobile phase, and 27.05 and 26.93 min, respectively, in a HPLC system using a Waters Nova Pack C18 column and methanol-based mobile phase. In a HPLC system using a Waters Nova Pack C18 column and acetonitrile-based mobile phase, the retention times were 10.73, 10.48 and 10.70 min for the new peak, authentic all-trans-beta-carotene, and 9-cis-beta-carotene, respectively. Spectrophotometry with a photodiode array detector showed maximum absorption of 447 and 475 nm for the new peak, and 450 and 475 nm for authentic all-trans-beta-carotene. This new peak was not observed in the lung tissue of control mice. These findings indicate the possible conversion of beta-cryptoxanthin to a beta-carotene like-compound in ddY mice.