New norlignan enantiomers from the fruit of Crataegus pinnatifida with neuroprotective activities

Publication date: Available online 21 September 2019Source: Chinese Chemical LettersAuthor(s): Rui Guo, Tianming Lv, Fengying Han, Zilin Hou, Guodong Yao, Bin Lin, Xiaobo Wang, Xiaoxiao Huang, Shaojiang SongABSTRACT(±)-Crataegusnorin A (1a/1b) and B (2a/2b), two pairs of rare 8,9′-epoxy-type norlignan enantiomers featuring a γ-butyrolactone ring, were isolated from the fruit of Crataegus pinnatifida. Their structures were determined via extensive spectroscopic analyses. Gauge-independent atomic orbital (GIAO) NMR chemical shift calculations, combined with the advanced statistical method DP4+ were employed to establish the relative configurations of four compounds. Next, chiral separation was accomplished by chiral chromatographic column and the absolute configurations of the four compounds were unambiguously assigned by comparison between their experimental electronic circular dichroism curves with the quantum-mechanically calculated curves based on time-dependent density functional theory (TDDFT). All the isolates were evaluated for their neuroprotective activities against H2O2-induced cell injury in human neuroblastoma SH-SY5Y cells. The results showed that two pairs of enantiomers 1a/1b and 2a/2b displayed different effect on neuroprotective activity. Among them, compound 2a displayed the most potent neuroprotective effect. Further flow cytometry analysis indicated that 2a could protect SH-SY5Y cells from oxidative damage through inhibiting cell apoptosis.Graphical Ab...
Source: Chinese Chemical Letters - Category: Chemistry Source Type: research