Neonatal hypoxic/ischemic encephalopathy (NHIE) is a severe condition that leads to death or neurological disability in newborns. The underlying pathological mechanisms are unclear, and developing the target neuroprotective strategies are urgent. 2,7,2′-trihydroxy-4,4′7′-trimethoxy-1,1′-biphenanthrene (TTB) is a natural product isolated from Cremastra appendiculata (D. Don) Makino and Liparis nervosa (Thunb.) Lindl. TTB has demonstrated potent cytotoxic activity against stomach (HGC-27) and colon (HT-29) cancer cell lines. However, none of the studies have addressed the effects of TTB in NHIE. In the present study, an oxygen-glucose deprivation/reoxygenation (OGD/R)-induced astrocyte injury model was established to investigate the effect of TTB and its potential mechanisms. Our results showed that TTB alleviated the OGD/R-induced reactive oxygen species increase and the intracellular antioxidant capacity of superoxide dismutase activity decrease. Moreover, TTB potentially prolonged the activation state of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway and maintained the protection against oxidative stress in OGD/R-induced astrocytes by inducing the nuclear translocation and up-regulation of Nrf2 along with the enhanced expression of the downstream target gene HO-1. Furthermore, TTB treatment diminished the accumulation of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) expression induced by OGD/R. We also found TTB-treated astrocytes reversed the inhibition of OGD/R on neurite growth of neurons by the astrocyte-neuron coculture system. In conclusion, TTB inhibited the OGD/R-induced astrocyte oxidative stress at least partially through the inhibition of HIF-1α and VEGF via the Nrf2/HO-1 signaling pathway.

BackgroundGastric cancer (GC) is the second leading cause of cancer death worldwide. Current chemotherapeutic drugs exert therapeutic effects accompanied by severe side effects. Therefore, it is imperative to urgently find new drugs with low toxicity and high efficacy for the treatment of GC. Natural products as well as functional foods have always been rich sources of potential antitumor agents. Pholidota cantonensis Rolfe, a well-known functional food and a traditional Chinese medicine, has been used for a long time in China for inflammatory diseases. Previously, we have evaluated its possible antitumor potentials by screening different solvent extracts, and found that the ethyl acetate (EtOAc) extract showed potent cytotoxicity on human GC cell line AGS with an IC50 value of 33.68 ± 1.68 μg/mL. In view of the poor knowledge concerning the phytochemical and pharmacological study of P. cantonensis, it is essential to characterize the active compounds from EtOAc extract and the mechanisms of action underlying the antitumor effect of the herb.ObjectiveThis study aimed to identify the primary compounds in EtOAc extract of P. cantonensis involved in the antitumor activity of the plant by evaluating the cytotoxicity in two human GC cell lines, including AGS and BGC-823 cells. Since endoplasmic reticulum (ER) stress-induced cell apoptosis represents attractive targets for cancer therapy recently, we focused on the underlying mechanisms associated with ER stress-induced cell apoptosis and related signaling pathways.MethodsVarious chromatographic techniques, including silica gel, Sephadex LH-20, and octadecylsilyl silica gel (ODS) C18, were used to separate the main active compound from EtOAc extract of P. cantonensis. The cell viability of AGS and BGC-823 cells upon purified compound treatment was determined by a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The alteration of cell morphology was observed using an inverted microscope. Cell apoptosis was determined by fluorescein isothiocyanate (FITC)-labeled annexin-V/propidium iodide (PI) double-staining and flow cytometry analysis. Western blot analyses were performed to examine the levels of intracellular signaling molecules involved in ER stress-induced apoptosis.ResultsA rare stilbene derivative pholidonone was isolated and identified. The results showed that pholidonone displayed potent cytotoxicity on human GC cells. The IC50 values for 24 and 48 h in AGS cells were 26.54 ± 0.32 and 25.20 ± 3.67 μM, and the IC50 values for 24 and 48 h in BGC-823 cells were 32.41 ± 3.83 and 17.28 ± 2.30 μM, respectively. In addition, pholidonone had pro-apoptotic effect on AGS and BGC-823 cells, and it upregulated the levels of proteins involved in ER stress, including BiP, PDI, Calnexin, Ero1-Lα, IRE1α, PERK, CHOP, and cleaved-caspase-3 in AGS and BGC-823 cells.ConclusionPholidonone can trigger ER stress-induced apoptosis through PERK and IRE1α signaling pathways. Pholidonone might be a potential naturally occurring antitumor agent.