fig2

Figure 2. Mechanisms of photo-induced membrane damage. This graphical sketch represents how Type I and Type II photochemical reactions contribute to membrane leakage through lipid damage. Type I reactions lead to changes in membrane fluidity which occur as a result of direct-contact reactions between the PS triplet [PS (T₁)] and either the lipid double bond of LH or the LOOH. Type II reactions [PS (T₁) and molecular oxygen (³O₂)] generates singlet oxygen (¹O₂) which leads to the formation of hydroperoxide (LOOH) as primary product. Modified from^[18]. R•: generic radical species; LH: non-oxidized lipid; L•, LOO•, LO•: lipid carbon-centered, peroxyl and alkoxyl radicals; LOOH, LOH, LO, LO*: lipid hydroperoxide, alcohol, ketone and excited state ketone