Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
The New Zealand Institute for Plant and Food Research Limited, Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
J Nat Prod. 2022 Aug 26;85(8):1904-1911. doi: 10.1021/acs.jnatprod.2c00207. Epub 2022 Jul 25.
Flavonoids acylated on their core phenolic groups are rare. The Aotearoa New Zealand endemic alpine daisy is widespread, but its flavonoids have not previously been identified. Leaf extracts yielded a series of 8--acylated flavones with combinations of 3-methylbutanoate, 2-methylbutanoate, and 2-methylpropanoate groups and one, two, or three -methyls, all previously unreported. Regiochemistries of 8-(3″-methylbutanoyl)-5-hydroxy-6,7,4'-trimethoxyflavone () and 8-(2″-methylbutanoyl)-5,7,4'-trihydroxy-6-methoxyflavone () were defined by X-ray crystallography. LC analyses of leaf extracts from the full geographic range of showed intraspecific variation of these flavones: most had high concentrations of trimethoxy 8--acylated flavones, but dimethoxy 8--acylated flavones were the most abundant flavonoids in two individuals. Three other viscid (sticky leaved) species also contained these rare flavones, but four nonviscid had none detectable.
酰化在其核心酚基团上的类黄酮很少见。新西兰特有高山雏菊分布广泛，但它的类黄酮以前尚未被发现。叶提取物产生了一系列 8-酰化黄酮，其中包括 3-甲基丁酰基、2-甲基丁酰基和 2-甲基丙酰基基团，以及一个、两个或三个甲基，均为以前未报道过的。通过 X 射线晶体学确定了 8-(3″-甲基丁酰基)-5-羟基-6,7,4'-三甲氧基黄酮 () 和 8-(2″-甲基丁酰基)-5,7,4'-三羟基-6-甲氧基黄酮 () 的区域化学。对来自全地理范围的叶片提取物进行 LC 分析表明，这些黄酮类化合物存在种内变异：大多数具有高浓度的三甲氧基 8-酰化黄酮，但二甲氧基 8-酰化黄酮在两个人中是最丰富的类黄酮。另外三个粘性（粘性叶片）物种也含有这些罕见的黄酮类化合物，但四个非粘性物种没有检测到。
