Tetrathiaporphyrine: A Novel Natural Product from Allium Subgenus Melanocrommyum

Abstract

AbstractA novel purple‐red pigment from the plant genus of Allium (onions, leeks), subgenus Melanocrommyum (drumstick onions), is described. Because of this pigment, which reminds of blood, some species of the subgenus Melanocrommyum are used in Southwest and Central Asia as herbal medications, as spices or as vegetables. A proposal for the formation of this structure is provided, which is the first example of a tetrathiaporphyrin in nature. The described substance shows low stability towards thermal stress, light and oxidant; additionally, its symmetric nature made structural elucidation a challenge. It could be shown that, contrary to previous reports, the structure of the red pigment is that of a tetrathiaporphyrin. Full structure elucidation was only possible by X‐ray crystallography and total synthesis of the intended molecule. Further on, the newly discovered red pigment was used for the modification of nanoparticles and monitoring its polymerization events using SPR.