Additionally, a computational study using density functional
theory has concluded that while the physical quenching pathway
described in Eqs. (1 and 2) is the most favored mechanism
for carotenoid and singlet oxygen interaction, the excited state
carotenoids may also follow a chemical degradation pathway
that is still not well understood (Garavelli et al., 1998). This
study suggests that the chemical pathway might involve a direct
attack on the double bonds of the carotenoid by singlet oxygen,
which forms biradicals that can eventually lead to carbonyl
chain cleavage products