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The tetrapyrrolic chlorophyll catabolites (or phyllobilins, PBs) were analyzed in yellow fall leaves of the grape Chardonnay, a common Vitis vinifera white wine cultivar. The major fractions in leaf extracts of V. vinifera, tentatively assigned to PBs, were isolated and their structures elucidated. The dominant fraction is a dioxobilin-type non-fluorescent Chl-catabolite of a previously observed type. Two less polar fluorescent PBs were characterized as a novel dioxobilin-type fluorescent Chl-catabolite with a bicyclo-1',6'-glycosyl architecture, and its new fluorescent formyloxobilin-type analogue. The discovery of persistent hypermodified fluorescent PBs with the architecture of bicyclo-[17.3.1]-PBs (bcPBs), suggests the activity of an unknown enzyme that forges the 20-membered macroring at the tetrapyrrolic core of a fluorescent PB. bcPBs may play specific physiological roles in grapevine plants and represent endogenous anti-infective agents, as found similarly for other organic bicyclo-[n.3.1]-1',6'-glycosyl derivatives., (© 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Twenty years ago, the molecular basis for the seasonal disappearance of chlorophyll was still enigmatic. In the meantime, our knowledge on chlorophyll breakdown has grown considerably. As outlined here, it has been possible to decipher the basic transformations involved in natural chlorophyll breakdown by identification of chlorophyll catabolites in higher plants, and with the help of the synthesis of (putative) catabolic intermediates. In vascular plants, chlorophyll breakdown typically converts the green plant pigments efficiently into colorless and non-fluorescent tetrapyrroles. It involves colored intermediates only fleetingly and in an (elusive) enzyme-bound form. The non-fluorescent chlorophyll catabolites accumulate in the vacuoles of degreened leaves and are considered the products, primarily, of a detoxification process. However, they are effective antioxidants, and may thus also have physiologically beneficial chemical properties.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009).