Novel Types of Hypermodified Fluorescent Phyllobilins from Breakdown of Chlorophyll in Senescent Leaves of Grapevine (Vitis vinifera).

Erhart, Theresia; Mittelberger, Cecilia; Liu, Xiujun; Podewitz, Maren; Li, Chengjie; Scherzer, Gerhard; Stoll, Gertrud; Valls, Josep; Robatscher, Peter; Liedl, Klaus R.; Oberhuber, Michael; Kräutler, Bernhard

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. The colors of the fall: Blue fluorescent chlorophyll catabolites with a unique bicyclo‐1′,6′‐glycosyl architecture occur in golden yellow fall leaves of Chardonnay, a common white wine cultivar. This discovery implies unknown enzymes that assemble a 20‐membered macroring at a tetrapyrrole to generate exceptionally structured chlorophyll catabolites. Possibly, these may play specific physiological roles and/or represent anti‐infective agents in the grapevine leaves.

HYDROXYLATION; VITIS vinifera; FLUORESCENCE; CATABOLITE repression; CHEMICAL decomposition; ISOMERIZATION

Chemistry - A European Journal, 2018, Vol 24, Issue 65, p17268

0947-6539

Academic Journal

10.1002/chem.201803128