Weicheng Hu

Antioxidant properties and neuroprotective effects of isocampneoside II on hydrogen peroxide-induced oxidative injury in PC12 cells

Oxidative stress has been considered as a major cause of cell damage in various neurodegenerative disorders. One of the reasonable strategies for delaying the diseases progression is to prevent reactive oxygen species (ROS) mediated cellular injury by dietary or pharmaceutical augmentation of free radical scavengers. Isocampneoside II (ICD) is an active phenylethanoid glycoside isolated from the medicinal hardwood genus Paulownia. This study was designed to explore free radical scavenging potential of ICD in different in vitro systems and its protective role in hydrogen peroxide (H₂O₂)-induced oxidative stress and apoptotic death in cultured rat pheochromocytoma (PC12) cells. The results showed ICD eliminated approximately 80.75% superoxide radical at the concentration of 0.1mg/ml and inhibited metal chelating by 22.07% at 8 mg/ml. Additionally, ICD showed a strong ability on reducing power and provided protection against oxidative protein damage induced by hydroxyl radicals. Pretreatment of PC12 cells with ICD prior to H₂O₂ exposure elevated cell viability, enhanced activity of superoxide dismutase and catalase, and decreased levels of malondialdehyde and intracellular ROS. Furthermore, ICD inhibited cell apoptosis and Bax/Bcl-2 ratio induced by H₂O₂. These findings suggested ICD may be considered as a potential antioxidant agent and should encourage for further research in neurodegenerative diseases.

Induction of cell cycle arrest and apoptosis by the ethyl acetate fraction of Kalopanax pictus leaves in human colon cancer cells.

Kalopanax pictus is a deciduous tree used in traditional medicine; its leaves are also consumed as a vegetable. In this study, the ethyl acetate fraction of K. pictus leaves (EFK) was tested in vitro for anticancer activity against four cell lines: human colon cancer (HT-29) cells, human stomach cancer (NCI-N87) cells, human breast cancer (MDA-MB231) cells, and mouse melanoma (B16F1) cells. Results indicated that EFK showed the most potent tumor selective growth inhibitory activity against HT-29 cells with less cytotoxic effect on normal cell lines. Cytotoxicity of EFK on HT-29 cells was associated mainly with cell chromatin condensation, DNA fragmentation, and loss of membrane phospholipid asymmetry with appearance of G2/M phase arrest. Cell death induced by EFK displayed features characteristic of apoptosis, and was associated with generation of reactive oxygen species (ROS) and increase of Bax/Bcl-2 ratio. These findings suggest that K. pictus leaves have anticancer properties and may be valuable for application in pharmaceutical industry.

Antioxidant and antiproliferative properties of water extract from Mahonia bealei (Fort.) Carr. leaves.

Mahonia bealei (Fort.) Carr. (Berberidaceae) leaves have been widely used as a tea leaf beverage south of the Qinling Mountains of China. In this study, the antioxidant and antiproliferative properties of M. bealei leaves were investigated. Our data showed that the water extract of M. bealei leaves (WML) exhibited extremely high antioxidant properties, which were demonstrated by its ability to scavenge 50% of 1,1-diphenyll-2-2-pricylhydrazyl (DPPH) free radicals at 60.46 μg/ml, and it eliminated approximately 71.19% of superoxide radicals at 500 μg/ml. In addition, the WML showed strong reducing abilities and provided protection against oxidative protein damage induced by hydroxyl radicals. Cellular proliferation and the induction of apoptosis were also examined by cellular proliferation assay, flow cytometry, and mRNA expression analysis. These results demonstrate that WML significantly inhibited the growth of human colon cancer (HT-29) cells in a concentration-dependent manner, and it gradually increased the proportion of apoptotic cells and reduced the expression of the survivin gene. The bioactivity-guided study of WML resulted in the isolation and identification of berberine, a known isoquinoline alkaloid. Berberine exhibited strong antiproliferative activity on HT-29 cells, with IC(50) values of 36.54 μM, suggesting it is, in part, responsible of the anticancer activity of WML.

Protective effect of the methanolic extract from Duchesnea indica against oxidative stress in vitro and in vivo.

Duchesnea indica (Rosaceae family) is herb used extensively in traditional Chinese medicine. In this study we investigated its protective activity against hydrogen peroxide (H(2)O(2))-induced cytotoxicity in human skin fibroblast (CCD-986Sk) cells and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced H(2)O(2) in the skin of hairless mice. Pretreatment of CCD-986Sk cells with methanolic extract of D. indica (DIM) improved the cell viability, enhanced activity of catalase, and decreased the leakage of lactate dehydrogenase (LDH) and the levels of malondialdehyde (MDA) and intracellular reactive oxygen species (ROS) in H(2)O(2) injured cells. Furthermore, DIM inhibited cell apoptosis and Bax expression induced by H(2)O(2). In addition, the level of H(2)O(2) stimulated by TPA was decreased by DIM in the skin of hairless mice. These results suggest that DIM offers protection against oxidative stress in vitro and in vivo, and this ability suggests potential use for protection against oxidation-induced skin damage.

Cell cycle arrest and apoptosis induced by methyl 3,5-dicaffeoyl quinate in human colon cancer cells: Involvement of the PI3K/Akt and MAP kinase pathways

Methyl 3,5-dicaffeoyl quinate (MDQ) is a flavonoid glucoside found in several plants that scavenges 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals and peroxynitrite, and inhibits the formation of cholesteryl ester hydroperoxide during the copper ion-induced oxidation of blood plasma in rats. In this study, MDQ inhibited proliferation and induced apoptosis in HT-29 cells in a dose-dependent manner as detected by 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT), trypan blue exclusion, and flow cytometric assays. Western blot analysis showed that apoptosis was dependent on caspase-3 activity. PARP cleavage and the cytosolic release of cytochrome c from mitochondria increased significantly. In addition, these events were accompanied by a collapse in the mitochondrial membrane potential and a decreased Bcl-2/Bax ratio. Furthermore, the MDQ-induced G(0)/G(1) arrest was correlated with an increase in p27 and a decrease in cyclin D1 and p53. MDQ also inhibited the phosphorylation of PI3K/Akt and ERK; significantly reduced NF-κB; and in general displayed a significant anti-proliferative effect via a cell cycle arrest and apoptotic induction in HT-29 cells. These results suggest that MDQ has therapeutic potential against human colon carcinoma.

Gusanlungionosides A-D, potential tyrosinase inhibitors from Arcangelisia gusanlung.

Four new megastigmane glycosides, named gusanlungionosides A-D (1-4), together with 10 known compounds (5-14), were isolated from the stems of Arcangelisia gusanlung. The structures and absolute configurations of 1-4 were elucidated by comprehensive analysis of their NMR and CD data. Compounds 1-4 exhibited strong inhibitory effects not only on the mushroom tyrosinase activity in vitro but also on melanogenesis in cells.

A new cis-p-coumaroyl flavonol glycoside from the inner barks of Sophora japonica L.

Abstract Tree barks could be a rich source of novel bioactive compounds, which are not well explored. In this work, the chemical constituent investigation of extractives from the inner barks of Sophora japonica L. (Leguminosae) led to the isolation of a new cis-p-coumaroyl flavonol glycoside, which was elucidated as kaempferol 3-O-(4″-cis-p-coumaroyl)-α-rhamnopyranoside (IV). The structure of the new compound was established mainly based on extensive spectroscopic techniques. In addition, among the four known phenolics purified in this study, including three flavonol glycosides [rutin (I), kaempferol-3-O-(6″-galloyl)-β-glucopyranoside (II), and quercitrin (V)], as well as a phenolic acid [trans-ferulic acid (III)], compounds II and III have never been reported in S. japonica previously.

Antioxidant and Nitric Oxide Production Inhibitory Activities of Scouring Rush (Equisetum hyemale L.)

Antioxidant and nitric oxide (NO) production inhibitory activities of various extracts from scouring rush (Equisetum hyemale L.) were investigated. Antioxidant assays including DPPH free radical scavenging activity, reducing power assay, metal-chelating assay, superoxide radical scavenging assay, and nitrite scavenging ability, and assays to determine total phenolic and flavonoid contents were performed. The inhibition of NO production was measured in lipopolysaccharides (LPS)-induced RAW 264.7 macrophages, and reverse transcription (RT)-PCR was used to analyse the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) in RAW 264.7 macrophages. Overall, all extracts showed high phenolic content and strong DPPH radical scavenging ability. Methanol extract exhibited stronger metal-chelating activity and NO production inhibitory activity compared with other extracts. The expression of iNOS and COX-2 was obviously augmented in response to LPS. Taken together, scouring rush could be used as a suitable natural antioxidant and a source of anti-inflammatory agent.

Antioxidative activity and anti-inflammatory effects of diarylheptanoids isolated from Alnus hirsuta

Two diarylheptanoids, 1,7-bis-(3,4-dihydroxyphenyl)-heptane-3-one-5-O-β-d-xylopyranoside (I) and 1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-β-d-xylopyranoside (II), were isolated from the bark of Alnus hirsuta. Compounds I and II exhibited strong antioxidative activity against 1,1-diphenyl-2-picrylhydrazyl radicals, with IC50 values of 8.36 ± 0.54 and 8.67 ± 1.46 μM, respectively. In addition, we demonstrated that compounds I and II inhibited the production of nitric oxide and reactive oxygen species and the expression of proinflammatory molecules such as inducible nitric oxide synthase and cyclooxygenase-2 in lipopolysaccharide-induced macrophages. According to our results, the two diarylheptanoids isolated from the bark of A. hirsuta exhibited significant antioxidative activity and anti-inflammatory effects and may be useful in the pharmaceutical industry for alleviating oxidative stress.

Phytochemical Investigation of Hydroalcoholic Extractives from Branches of Fraxinus velutina

The genus Fraxinus (Oleaceae) contains approximately 70 woody species, which are widely distributed in the temperate regions and the subtropics of the Northern Hemisphere, including Eastern Asia, Europe, and North and Central America [1–4]. Fraxinus plants are highly valued in folk medicines for their diuretic and mild purgative effects as well as for treatment of arthritis, dropsy, constipation, rheumatic pain, cystitis, and itching scalp [4, 5]. The chemical composition of Fraxinus species consists mainly of flavonoids [1, 6], secoiridoids [7, 8], coumarins [9, 10], phenylethanoid glycosides [11, 12], and lignans [13, 14], but very few chemical investigations have been reported on F. velutina Torr. until now. In this investigation, F. velutina branches were collected in November 2012, in Tianjin, China, where F. velutina is authorized as the Tree of Tianjin City. Taxonomic identification was done by Prof. Dan Wang, Institute of Chemical Industry of Forest Products, CAF, China. The air-dried and finely powdered branches of F. velutina (8.5 kg) were extracted in a 30 L jar with 95% EtOH (v/v) solution for more than four days at room temperature. After evaporation of the solvent under reduced pressure, the residue was partitioned consequently with n-hexane, chloroform, ethyl acetate, and n-buthanol, then freeze-dried to give powders of the four portions. Part of the resulting ethyl acetate portion powders (31.2 g) were subjected to column chromatography packed with silica gel or Sephadex LH-20 successively, which led to the isolation of nine secondary metabolites. By spectroscopic methods and comparison with authentic data, the structures of the nine compounds were elucidated as (–)-epigallocatechin (1) [15], naringenin (2) [16], taxifolin (3) [17], rutin (4) [18], apigenin-7-O-[ -Dglucuronopyranosyl(1 2)-O-D-glucuronopyranoside] (5) [19, 20], esculin (6) [21], esculetin (7) [21], ligstroside (8) [22], and oleuropein (9) [22]. All these compounds were isolated from F. velutina branches for the first time, and compounds 1–3, and 5 have never been reported from the genus Fraxinus previously. The flavonoids (1–5), coumarins (6 and 7) and secoiridoids (8 and 9) reported herein suggested that the main constituents of F. velutina were in good accordance with those of other species of the genus Fraxinus. Although the chemical shifts of 5 have been described in the literature [19, 20], the assignment of the sugar moieties was always confusing, and no completely assigned NMR data have been published. In this work, we give the exact and unambiguous 1H and 13C NMR assignments of this flavonoid glycoside derivative for the first time, achieved with the aid of 2D NMR techniques.