Figures & data
Fig. 1 Extracts of propolis attenuate oxygen-induced-deprivation (OGD)-induced cell damage. a) Cytotoxicity test of water- or alcohol-soluble extracts from propolis in N2a cell. Ligustrazine was a control for cell protection. b) Optimization of the effect of OGD on cell damage in different time courses. c) Illustration of cell death 4 h after OGD treatment. Ligustrazine can protect cell from damage. d) The effect of water- or alcohol-soluble extracts from propolis on OGD-induced cell damage. Ligustrazine was a positive control for cell protection. e) Image of cell phenomena for water- or alcohol-soluble extracts from propolis in cell-protection effects. n=3 for each group; *p<0.05; **p<0.01.
Fig. 2 The protection effect of serial extracts from propolis on OGD-induced cell death. a) The procedure of extraction by organic solvent and column chromatography. b) Cell-protection effects by extracts with different doses, including petroleum ether, dichloromethane, ethyl acetate, and acetone from propolis after organic solvent extraction. c) Cell morphology for protection effects by propolis extracts in N2a cell 4 h after OGD treatment. d) Cell protection assay in an OGD-treated N2a cell of fraction one to five from dichloromethane extracts of propolis by column chromatography. n=3 for each group; *p<0.05; **p<0.01.
Fig. 3 Spectrums of mass spectrometry for five compounds identification after HPLC purification from fraction three extracted from dichloromethane extracts of propolis. a) Pinocembrin in fraction 1; b) galangin in fraction 2; c) chrysin in fraction 3; d) pinobanksin 3-O-acetate in fraction 4; and e) pinobanksin in fraction 5.
Fig. 4 The cell-protection effects of five compounds from serial purification on an OGD-treated N2a cell. a) Cytotoxicity assay for all compounds in different dose. b) Compounds extracted from propolis enhanced superoxide dismutase (SOD) to protect cell from damage induced by OGD. c) Down-regulated oxidative stress marker, malondialdehyde (MDA), in propolis extracts treated N2a cell after OGD induction. d) The antioxidant, glutathione (GSH), was increased in propolis extracts treated N2a cell after OGD induction. e) Ca2+ influx was reduced in propolis extracts treated N2a cell after OGD induction. n=3 for each group; *p<0.05; **p<0.01; compound-treated groups were compared with the OGD-treated only group.
Fig. 5 Compounds from propolis extracts can inhibit apoptosis induced by OGD in N2a cell. Cell apoptosis induced by OGD and rescued by compound treatment was checked by flow cytometry.
Fig. 6 Apoptosis-related proteins were significantly altered in compounds from a propolis-treated OGD-induced N2a cell. a) Propolis extract compounds inhibited vaspase-3 expression level in N2a cell after OGD induction. b) Propolis extract compounds enhanced Bax expression level in an N2a cell after OGD induction. c) Propolis extract compounds inhibited Bcl-2 expression level in an N2a cell after OGD induction. n=3 for each group; *p<0.05; **p<0.01; compound-treated groups were compared with the OGD-treated only group.
