Zhenliang Sun

Antioxidant and antihyperlipidemic activities of polysaccharides from sea cucumber Apostichopus japonicus

Polysaccharides (AJP) were prepared from Apostichopus japonicus by protease hydrolysis method. Antioxidant activity in vitro and antihyperlipidemic activity in vivo was investigated. Chemical composition analysis indicated that AJP was mainly composed of glucosamine, galactosamine, glucuronic acid, mannose, glucose, galactose and fucose, with an average molecular weight of about 36.2 kDa. The antioxidant capacities of AJP were, respectively, evaluated by the assays of scavenging DPPH, hydroxyl and superoxide radicals, and reducing power in vitro. It showed potent free radical scavenging activities and reducing power. Serum total cholesterol (TC), triglyceride (TG) and low-density lipoprotein (LDL-C) decreased significantly and high-density lipoprotein cholesterol (HDL-C) increased significantly after treatment of hyperlipidemic Wistar rats with AJP. These results suggest that AJP may prove to be a potential candidate of the natural antioxidants as a therapeutic agent for hyperlipidemia.

Antifungal and cytotoxic activities of the secondary metabolites from endophytic fungus Massrison sp.

Three novel compounds with spiro-5, 6-lactone ring skeleton has been isolated from the fermentation broth of Massrison sp. which could be isolated repeatedly from wild Rehmannia glutinosa. Psetariae oryza P-2b was applied to guide fractionation of bioactive compounds produced by Massrison sp. The molecular structures were established by a variety of one- and two-dimensional NMR experiments and the compounds with similar skeleton were reported for the first time from endophytic fungi of terraneous plant. Antifungal and cytotoxic activities of the compounds were tested, compounds 2 and 3 displayed stronger antifungal and cytotoxic activities. The compounds have the potential to be antibiotic against fungal pathogens and tumor cells.

Cellulase-assisted extraction, characterization, and bioactivity of polysaccharides from Polygonatum odoratum

Cellulase-assisted extraction of polysaccharides from Polygonatum odoratum (CPP) was optimized by response surface methodology (RSM) and the extracted CPPs preliminary chemical characteristics, as well as antioxidant and immunomodulatory activities were also investigated. The optimal extraction parameters comprised an extraction temperature of 58.21 °C, an extraction time of 3.18 h, pH value of 5.8, and cellulase amount of 6.0%. Under these conditions, the relative yield was 15.76%, higher than the yield achieved with hot water extracted polysaccharide (HPP). Chemical composition analysis demonstrated that CPP and HPP consisted of mannose, glucosamine, rhamnose, glucose, galactose, and arabinose with a molecular ratio of 7.80:1.08:1.63:65.93:3.58:1.00 and 11.22:0.23:0.23:17.59:2.73:9.10, respectively. The molecular weight distribution of CPP was lower and more homogeneous compared with HPP. CPP exhibited stronger antioxidant activities than HPP, including DPPH radical scavenging activity and reducing power. Both CPP and HPP could significantly promote the proliferation and neutral red phagocytosis of RAW 264.7 macrophage cells in vitro. These results indicate that the cellulase-assisted extraction method influenced the physicochemical characteristics, and consequently, the functional activities of polysaccharides, suggesting the cellulose-assisted method may be a viable option for extraction polysaccharides from P. odoratum.

Extraction, Preliminary Characterization and Evaluation of in Vitro Antitumor and Antioxidant Activities of Polysaccharides from Mentha piperita

This study describes the extraction, preliminary characterization and evaluation of the in vitro antitumor and antioxidant activities of polysaccharides extracted from Mentha piperita (MPP). The optimal parameters for the extraction of MPP were obtained by Box-Behnken experimental design and response surface methodology (RSM) at the ratio of water to raw material of 20, extraction time of 1.5 h and extraction temperature at 80 °C. Chemical composition analysis showed that MPP was mainly composed of glucuronic acid, galacturonic acid, glucose, galactose and arabinose, and the molecular weight of its two major fractions were estimated to be about 2.843 and 1.139 kDa, respectively. In vitro bioactivity experiments showed that MPP not only inhibited the growth of A549 cells but possessed potent inhibitory action against DNA topoisomerase I (topo I), and an appreciative antioxidant action as well. These results indicate that MPP may be useful for developing safe natural health products.

A new neuroprotective bakkenolide from the rhizome of Peatasites tatewakianus

Constituents of the fruits of Peatasites tatewakianus were investigated. A new compound, namely bakkenolide-VI (1), was isolated. The structures was elucidated on the basis of 1D, 2D NMR, TOF-MS and ESI-MS techniques, and physicochemical properties. The neuroprotective activity of the new compound was assayed with primary cultured neurons exposed to oxygen-glucose deprivation and oxidative insults.

A new hepoprotective saponin from Semen Celosia cristatae

A new triterpenoid saponin, named semenoside A (1), was isolated from Semen Celosia cristatae. Its structure was elucidated on the basis of 1D, 2D NMR, HR-FAB-MS and ESI-MS techniques, and physicochemical properties. The hepatoprotective activity of semenoside A with an oral dose of 1.0, 2.0 and 4.0mg/kg, respectively, were investigated by carbon tetrachloride (CCl(4))-induced hepatotoxicity in mice. The results indicated that it had significant hepatoprotective effects (p < 0.01).

Polysaccharides extraction from Erythirna variegata, chemical characterization and its antioxidant activity.

The objective of this study was to determine the optimum conditions for extracting crude polysaccharides from the bark of Erythirna variegata (EVP) using response surface methodology (RSM). The quantitative effects of extraction time, temperature and the ratio of water to raw material on EVP yields were investigated using Box-Behnken experimental design. The monosaccharide composition was analyzed by 1-phenyl-3-methy-5-pyrazolone pre-column derivatization high performance liquid chromatography, and the molecular weight was measured by high performance gel permeation chromatography. The antioxidant activities were also evaluated. By solving the regression equation and analyzing the data, the optimum conditions were obtained as follows: extracting time 1.52h, extraction temperature 91.40°C, and the ratio of water to raw material at 24.78. Under these conditions, the experiment yield was 2.064%, which well agreed with the predicted value. Chemical composition analysis indicated that EVP was mainly composed of mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose, and the mean molecular weight of the two major fractions was about 26.8kDa and 5.5kDa, respectively. EVP had strong scavenging activity against DPPH radicals, potential reducing power and total antioxidant activity. This study provides a scientific basis for the use of this herb in traditional medicine as an antioxidant.

A preliminary study of side population cells in human gastric cancer cell line HGC-27.

BACKGROUND Cancer stem cell-like side population (SP) cells, which may be responsible for recurrence, tumor metastasis, and resistance to cancer therapy, have been identified and characterized in several types of cell lines from gastric cancer. However, there is no report on isolation of SP cells from human gastric cancer cell line HGC-27. This study aims to analyze the proportion of SP cells in HGC-27 cell line, differentiate SP from non-side population (NSP) cells, and determine whether the SP cells have certain biological properties of stem cells. MATERIAL AND METHODS (1) HGC-27 suspension was prepared and stained with Hoechst33342 and PI for flow cytometric isolation of SP (2). Differences in proliferation and stemness-related gene expression profiles (CD133, CD44, OCT-4, MDR1, EpCAM, and ABCG2) between SP and NSP cells were detected by gastric formation assay and quantitative real-time PCR (3). Oncogenicity of SP and NSP cells was determined in nude mice in vivo. RESULTS (1) SP cells accounted for 0.1-1.0% of HGC-27 cells, and decreased to 0% after verapamil inhibition. Using flow cytometry, we sorted 7.5×10⁵ SP cells and most HGC-27 cells were NSP cells (2). Gastric formation assay and MTT demonstrated that there was a significant difference in proliferation between SP and NSP cells. Gene expression analysis showed that the expression of genes was significantly higher in SP cells (3). The oncogenicity experiment in nude mice revealed that 105 SP cells were able to form tumors, which demonstrated higher tumorigenicity than non-SP cells. CONCLUSIONS These results collectively suggested that SP cells from HGC-27 cell line have some cancer stem cell properties and could be used for studying the pathogenesis of gastric cancer, which may contribute to discovery of novel therapeutic targets.

Production of the angiotensin I converting enzyme inhibitory peptides and isolation of four novel peptides from jellyfish (Rhopilema esculentum) protein hydrolysate

BACKGROUND Angiotensin I converting enzyme (ACE) plays an important role in regulating blood pressure in the human body. ACE inhibitory peptides derived from food proteins could exert antihypertensive effects without side effects. Jellyfish (Rhopilema esculentum) is an important fishery resource suitable for production of ACE inhibitory peptides. The objective of this study was to optimize the hydrolysis conditions for production of protein hydrolysate from R. esculentum (RPH) with ACE inhibitory activity, and to isolate and identify the ACE inhibitory peptides from RPH. RESULTS Rhopilema esculentum protein was hydrolyzed with Compound proteinase AQ to produce protein hydrolysate with ACE inhibitory activity, and the hydrolysis conditions were optimized using response surface methodology. The optimum parameters for producing peptides with the highest ACE inhibitory activity were as follows: hydrolysis time 3.90 h, hydrolysis temperature 58 °C, enzyme:substrate ratio 2.8% and pH 7.60. Under these conditions, the ACE inhibitory rate reached 32.21%. In addition, four novel ACE inhibitory peptides were isolated, and their amino acids sequences were identified as Val-Gly-Pro-Tyr, Phe-Thr-Tyr-Val-Pro-Gly, Phe-Thr-Tyr-Val-Pro-Gly-Ala and Phe-Gln-Ala-Val-Trp-Ala-Gly, respectively. The IC50 value of the purified peptides for ACE inhibitory activity was 8.40, 23.42, 21.15 and 19.11 µmol L(-1) . CONCLUSION These results indicate that the protein hydrolysate prepared from R. esculentum might be a commercial competitive source of ACE inhibitory ingredients to be used in functional foods.

Chemical Constituents of Fusarium sp. Fungus Associated with Sea Cucumbers

Marine fungi are increasingly a major focus of natural product research efforts and rich sources of novel bioactive compounds [1, 2]. In our continuing search for secondary metabolites produced by marine fungi that induce cytotoxicity or possess a novel chemical structure, we previously isolated diterpenes and benzofurans from fungi associated with sea cucumbers [3, 4]. Further searches for metabolites produced by the fungus Fusarium sp. led to the isolation of six compounds (1–6). The structure of compound 6 was confirmed by single-crystal X-ray diffraction using Mo K radiation. Compounds 5 and 6 were isolated from Fusarium sp. for the first time. Here we report the isolation and structures of compounds 1–6 and their cytotoxic activities against KB and KBv 200 cells. A strain (No. HS-4) of the fungus Fusarium sp. was isolated from the surface muscle of a sea cucumber from the Yantai sea (P. R. China) using PDA medium and was stored at –79 C at the Biology Institute of Shandong Academy of Sciences (Jinan City, Shandong Province, P. R. China). The fungal strain was cultivated at 28 C for 28 days in eight 500 mL Erlenmeyer flasks containing 80 g of rice with 120 mL of seawater. The cultures and mycelium were extracted three times with threefold volumes of ethyl acetate. The combined extracts were chromatographyed repeatedly on silica gel (200–300 mesh, Qingdao Marine Chemical Engineering, China) using gradient elution from petroleum ether to ethyl acetate to get 15 fractions. Fractions 7, 8, and 12 were further purified with Sephadex LH-20 and eluted with a solution of petroleum ether–CH2Cl2–MeOH (2:1:1) to obtain compounds 1 (3.2 mg), 2 (4.0 mg), 3 (2.0 mg), 4 (4.5 mg), 5 (3.4 mg), and 6 (3.0 mg). These compounds were identified as javanicin (1) [5], norjavanicin (2) [6], 5-hydroxy-7-methoxy-3-methyl-2-(2-oxopropyl)naphthalene-1,4-dione (3) [5], fusarubin (4) [5], terrein (5) [7, 8], and sclerin (6) [9] based on mass spectrometry, 1D and 2D NMR spectroscopy and by comparison with literature data. Single crystal X-ray diffraction analyses of compound 6 were carried out with a Rigaku XtaLAB mini diffractometer (Rigaku International Corp.) with graphite monochromated Mo K radiation ( = 0.71073 A ). The collected data were reduced using the CrystalClear program [10], and an empirical absorption correction was applied. The structure was solved by direct methods and refined based on F2 by full matrix least-squares methods using SHELXTL [11, 12]. All non-H atoms were refined anisotropically. The positions of hydrogen atoms attached to carbon atoms were determined geometrically.