Hans Marcus, Charpentier Maël, Huch Volker, Jauch Johann, Bruhn Torsten, Bringmann Gerhard, Quandt Dietmar
Institute of Organic Chemistry, Saarland University , Campus C 4.2, 66123 Saarbrücken, Germany.
Institute of Inorganic Chemistry, Saarland University , Campus C 4.1, 66123 Saarbrücken, Germany.
J Nat Prod. 2015 Oct 23;78(10):2381-9. doi: 10.1021/acs.jnatprod.5b00358. Epub 2015 Oct 12.
Myrtucommulone A (MC A) (1), isolated from Myrtus communis (myrtle), shows the same pharmacological activity for inhibition of inflammation and induction of apoptosis as synthetic MC A, which consists of three stereoisomers, i.e., two enantiomers and one meso form. This led to the question of whether the natural MC A is a pure stereoisomer or a mixture of stereoisomers. The specific rotation and electronic circular dichroism (ECD) data of natural MC A (1) as well as of a pentacyclic derivative 4 revealed that naturally occurring MC A (1) consists of the racemate and the meso form in a 1:1 ratio. A probable precursor of MC A (1), nor-semimyrtucommulone (5), was also isolated from myrtle as a racemate. The absolute configurations of the enantiomers of 1 and 5 were determined using a combination of experimental and quantum-chemical calculated ECD spectra.
从香桃木（桃金娘）中分离出的桃金娘科香叶木素A（MCA）（1），与由三种立体异构体（即两种对映体和一种内消旋体）组成的合成MCA具有相同的抑制炎症和诱导细胞凋亡的药理活性。这就引发了一个问题，即天然MCA是纯立体异构体还是立体异构体的混合物。天然MCA（1）以及五环衍生物4的比旋光度和电子圆二色性（ECD）数据表明，天然存在的MCA（1）由外消旋体和内消旋体以1:1的比例组成。MCA（1）的一种可能前体，去甲半桃金娘科香叶木素（5），也从香桃木中作为外消旋体分离出来。使用实验和量子化学计算的ECD光谱相结合的方法确定了1和5对映体的绝对构型。
