Cudrania Tricuspidata Extract and Its Major Constituents Inhibit Oxidative Stress-Induced Liver Injury.

The fruits, leaves, and roots of Cudrania tricuspidata have been reported to contain large amounts of vitamin B, vitamin C, and flavonoids. They exhibit various physiological activities such as antitumor and anti-inflammatory effects. However, the hepatoprotective effects of C. tricuspidata extracts against oxidative stress-mediated liver injury have not yet been investigated. We thus examined whether C. tricuspidata leaf extracts (CTEs) protect against oxidative stress-mediated liver injury in vitro and in vivo and elucidated the underlying mechanism. The cytoprotective effects of CTE through the NF-E2-related factor 2 (Nrf2)/antioxidant response element (ARE) activation were presented and measured by biochemical analysis in HepG2 cells. To assess the protective effects of CTE in vivo, mice were administered with CTE (250 and 500 mg/kg; 5 days; p.o.) before a single dose of acetaminophen (APAP) (300 mg/kg; 24 h; i.p.). CTE increased ARE luciferase activity when compared with extracts of other parts of C. tricuspidata. CTE upregulated nuclear translocation of Nrf2 and its target gene expression. In addition, CTE inhibited the generation of reactive oxygen species (ROS) and cell death induced by arachidonic acid (AA) and iron (Fe) treatment in primary hepatocytes or HepG2 cells. The cytoprotective effects of CTE against oxidative stress might be due to kaempferol, the major flavonoid present in CTE. Kaempferol pretreatment blocked AA+Fe-induced ROS production and reversed glutathione depletion, which in turn led to decreased cell death. Furthermore, the protective effects of CTE against liver injury induced by excess APAP in mice or primary hepatocytes were observed. CTE could be a promising therapeutic candidate against oxidative stress-induced liver injury.

Anti-Helicobacter pylori activity of crude N-acetylneuraminic acid isolated from glycomacropeptide of whey.

Helicobacter pylori colonizes the gastric mucosa of about half of the world's population, causing chronic gastritis and gastric cancer. An increasing emergence of antibiotic-resistant H. pylori arouses demand on alternative non-antibiotic-based therapies. In this study, we freshly prepared crude N-acetylneuraminic acid obtained from glycomacropeptide (G-NANA) of whey through a neuraminidase-mediated reaction and evaluated its antibacterial ability against H. pylori and H. felis. Overnight cultures of the H. pylori were diluted with fresh media and different concentrations (1-150 mg/mL) of crude G-NANA were added directly to the culture tube. Bacterial growth was evaluated by measuring the optical density of the culture medium and the number of viable bacteria was determined by a direct count of the colony forming units (CFU) on agar plates. For the in vivo study, mice were orally infected with 100 µL (5×10(8) cfu/mL) of H. felis four times at a day's interval, accompanied by a daily administration of crude G-NANA or vehicle. A day after the last infection, the mice were daily administered the crude G-NANA (0, 75, and 300 mg/mL) for 10 days and euthanized. Their stomachs were collected and bacterial colonization was determined by quantitative real-time PCR. Crude G-NANA inhibited H. pylori's growth and reduced the number of viable bacteria in a dose-dependent manner. Furthermore, crude G-NANA inhibited bacterial colonization in the mice. These results showed that crude G-NANA has antibacterial activity against Helicobacter and demonstrated its therapeutic potential for the prevention of chronic gastritis and gastric carcinogenesis induced by Helicobacter infection in humans.

Genetic Diversity of Pectobacterium carotovorum subsp. brasiliensis Isolated in Korea.

The plant pathogenic bacterial genus Pectobacteirum consists of heterogeneous strains. The P. carotovorum species is a complex strain showing divergent characteristics, and a new subspecies named P. carotovorum subsp. brasiliensis has been identified recently. In this paper, we re-identified the P. carotovorum subsp. brasiliensis isolates from those classified under the subspecies carotovorum and newly isolated P. carotovorum subsp. brasiliensis strains. All isolates were able to produce plant cell-wall degrading enzymes such as pectate lyase, polygalacturonase, cellulase and protease. We used genetic and biochemical methods to examine the diversity of P. carotovorum subsp. brasiliensis isolates, and found genetic diversity within the brasiliensis subsp. isolates in Korea. The restriction fragment length polymorphism analysis based on the recA gene revealed a unique pattern for the brasiliensis subspecies. The Korean brasiliensis subsp. isolates were divided into four clades based on pulsed-field gel electrophoresis. However, correlations between clades and isolated hosts or year could not be found, suggesting that diverse brasiliensis subsp. isolates existed.

Microbiota on spoiled vegetables and their characterization.

Spoilage causes vegetables to deteriorate and develop unpleasant characteristics. Approximately 30 % of fresh vegetables are lost to spoilage, mainly due to colonization by bacteria. In the present study, a total of 44 bacterial isolates were obtained from a number of spoiled vegetables. The isolates were identified and classified into 20 different species of 14 genera based on fatty acid composition, biochemical tests, and 16S rDNA sequence analyses. Pseudomonas spp. were the species most frequently isolated from the spoiled vegetables. To evaluate the spoilage ability of each species, a variety of fresh vegetables were treated with each isolate and their degree of maceration was observed. In addition, the production of plant cell wall-degrading enzymes (PCWDEs), such as cellulase, xylanase, pectate lyase, and polygalacturonase, was compared among isolates to investigate their potential associations with spoilage. Strains that produce more PCWDEs cause spoilage on more diverse plants, and pectinase may be the most important enzyme among PCWDEs for vegetable spoilage. Most gram-negative spoilage bacteria produced acylated homoserine lactone, a quorum-sensing signal molecule, suggesting that it may be possible to use this compound effectively to prevent or slow down the spoilage of vegetables contaminated with diverse bacteria.

Anti-fatigue activity of Hovenia dulcis on a swimming mouse model through the inhibition of stress hormone expression and antioxidation.

Hovenia dulcis (H. dulcis) Thunb., which is distributed in Korea, China, and Japan, has been known to show hepatoprotective and free radical scavenging effects and enhance physical activity. Therefore, the objectives of this present study were to determine the anti-fatigue activity of hot-water extract from H. dulcis peduncle, and to find the reason why H. dulcis extract (HDE)-ingested mice had enhanced physical activity against swimming performance. The mice orally administrated with HDE (HDE-mice) dramatically enhanced their swimming time compared to the control mice. HDE significantly decreased serum levels of stress hormones, such as cortisol and adrenocorticotropic hormone (ACTH) in mice. The levels of thiobarbituric acid reactive substances (TBARS) were dramatically decreased in gastrocnemius muscle from both 100 mg/kg of HDE (LHDE) and 200 mg/kg of HDE (HHDE)-ingested mice compared to the control mice. The liver activities of superoxide dismutase (SOD) were significantly increased in HHDE-mice with increasing tendency in LHDE-mice. In addition, HHDE-mice significantly decreased the levels of blood glucose, total cholesterol (T-Chol), and triglyceride (TG). These results suggest that HDE had a significant anti-fatigue effect via its anti-stress and antioxidant activities, and thereby enhanced physical activity in swimming performance.