AUTHOR=Zhou Mei , Jiang Sai , Chen Changfen , Li Jinyu , Lou Huayong , Wang Mengyun , Liu Gezhou , Liu Hanfei , Liu Ting , Pan Weidong 

TITLE=Bioactive Bibenzyl Enantiomers From the Tubers of Bletilla striata

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.911201

DOI=10.3389/fchem.2022.911201

ISSN=2296-2646

ABSTRACT=Six new bibenzyls (three pairs of enantiomers), bletstrins D-F (1-3), were isolated from the ethyl acetate-soluble (EtOAc) extract of tubers of Bletilla striata. Their structures, including absolute configurations were determined by 1D/2D NMR spectroscopy, optical rotation value and experimental electronic circular dichroism (ECD) data analyses, respectively. Compounds 1-3 possess a hydroxyl-substituted chiral center on the aliphatic bibenzyl bridge, which represented the first examples of natural bibenzyl enantiomers from the genus of Bletilla. The antibacterial, anti-tumor necrosis factor (anti-TNF-α) and neuroprotective effects of the isolates have been evaluated. Compounds 3a and 3b were effective against three gram-positive bacteria with minimum inhibitory concentrations (MICs) of 52-105 µg/mL. Compounds 2a and 2b exhibited significant inhibitory effects on TNF-α-mediated cytotoxicity in L929 cells with IC50 values of 25.7 ± 2.3 μM, 21.7 ± 1.7 μM respectively. Subsequently, the possible anti-TNF-α mechanism of 2 was investigated by molecular docking simulation. Furthermore, the neuroprotective activities were tested on H2O2-induced PC12 cells injury model, and compounds 2b, 3a, and 3b (10 μM) could obviously protected the cells with the cell viabilities of 57.86 ± 2.08%, 64.82 ± 2.84%, and 64.11 ± 2.52%, respectively.