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=10

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=<p>Six new bibenzyls (three pairs of enantiomers), bletstrins D–F (1–3), were isolated from the ethyl acetate-soluble (EtOAc) extract of tubers of <italic>Bletilla striata</italic> (Thunb.) Rchb f. 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 <italic>Bletilla</italic>. The antibacterial, antitumor necrosis factor (anti-TNF-<italic>α</italic>), 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-<italic>α</italic>-mediated cytotoxicity in L929 cells with IC<sub>50</sub> values of 25.7 ± 2.3 μM and 21.7 ± 1.7 μM, respectively. Subsequently, the possible anti-TNF-<italic>α</italic> mechanism of 2 was investigated by molecular docking simulation. Furthermore, the neuroprotective activities were tested on the H<sub>2</sub>O<sub>2</sub>-induced PC12 cell injury model, and compounds 2b, 3a, and 3b (10 μM) could obviously protect the cells with the cell viabilities of 57.86 ± 2.08%, 64.82 ± 2.84%, and 64.11 ± 2.52%, respectively.</p>