Effect of β-carotene on the transformation of tyrosine by nitrogen dioxide and peroxynitrous acid

Abstract

In the NO₂-exposure of tyrosine in 70% dioxane/phosphate buffer (pH 7.4), β-carotene enhanced the degradation of tyrosine and/or 3-nitrotyrosine produced, whereas α-tocopherol and ascorbyl palmitate inhibited the transformation of tyrosine into 3-nitrotyrosine. Generation of certain active species in the interaction of β-carotene with NO₂ was suggested. Ascorbyl palmitate effectively and α-tocopherol slightly inhibited the transformation of tyrosine in the NO₂-exposure in the presence of β-carotene. In the reaction of tyrosine with ONOO^-ON OOH, β-carotene enhanced the degradation of 3-nitrotyrosine produced suggesting generation of certain active species, whereas α-tocopherol and ascorbyl palmitate completely suppressed the transformation of tyrosine into 3-nitrotyrosine.

Keywords:

• β-Carotene
• nitrogen dioxide
• peroxynitrite
• tyrosine