Novel Types of Hypermodified Fluorescent Phyllobilins from Breakdown of Chlorophyll in Senescent Leaves of Grapevine (Vitis vinifera)
Theresia Erhart, Cecilia Mittelberger, Xiujun Liu, Maren Podewitz, Chengjie Li, Gerhard Scherzer, Gertrud Stoll, Josep Valls, Peter Robatscher, Klaus Liedl, Michael Oberhuber, Bernhard Kräutler
Chemistry A European Journal
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 analog. 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.
Circular dichroism, Stereochemistry, Natural products