Changes in chlorophylls resulting from various chemical and physical treatments of leaves and leaf extracts

Chlorophylls a and b are easily altered chemically when leaves or leaf extracts are exposed to treatments which include heating and the action of organic solvents. Monitoring by thin-layer chromatography assists in the detection of the chlorophyll derivatives. In addition to loss of magnesium, formation of chlorophyllides and the a′ and b′ isomers, and loss of colour, chlorophylls a and b can each be converted into two other derivatives, with absorption spectra almost identical with those of the parent compounds. The conditions of formation, purification and some of the properties of these derivatives are described, and possible structures are discussed.