The unusual conformational preference of N1,N5,N10-tri-p-coumaroylspermidine E-Z isomers from the Japanese apricot tree, Prunus mume, for the (ZZZ)-form

Publication date: June 2019Source: Phytochemistry Letters, Volume 31Author(s): Shinnosuke Mori, Miki Akamatsu, Hiroshi Fukui, Junko Tsukioka, Katsumi Goto, Nobuhiro HiraiAbstractThe Japanese apricot tree, Prunus mume (Siebold) Siebold & Zucc. cv. Nanko, bears two types of flowers: those with anthers that fluoresce under UV irradiation, and those that do not. The chemical composition of both types of anthers has been investigated: the non-fluorescent anthers contained eight E-Z isomers of N1,N5,N10-tri-p-coumaroylspermidine as major constituents; whereas the fluorescent anthers contained only a limited amount of (ZZZ)-isomer, but relatively large amounts of fluorescent chlorogenic acid, implying the abnormal development of fluorescent anthers. Of these eight E-Z isomers, three were undescribed, and identified as the (ZEZ)-, (ZEE)-, and (EEZ)-forms. Their photoequilibrium ratios were found to be characteristic, wherein the (ZZZ)-isomer predominated over the (EEE). 1H NMR and NOESY experiments and ab initio molecular orbital calculations indicated that intramolecular T-shaped π/π, CH/π, and OH⋯O = C hydrogen bonding interactions impart an unusual degree of stability to the (ZZZ)-isomer that is sufficient to overcome various factors that favor the (EEE)-form.Graphical abstract

Source: Phytochemistry Letters - April 6, 2019 Category: Chemistry Source Type: research