Jeong-Hwan Che

Preventive effect of epicatechin and ginsenoside Rb2 on the inhibition of gap junctional intercellular communication by TPA and H2O2

The anticarcinogenic effects of epicatechin (EC) and ginsenoside Rb(2) (Rb(2)), which are major components of green tea and Korea ginseng, respectively, were investigated using a model system of gap junctional intercellular communication (GJIC) in WB-F344 rat liver epithelial cells. 12-O-tetradecanoylphorbol-13-acetate (TPA) and hydrogen peroxide, known as cancer promoters, inhibited GJIC in the epithelial cells as determined by the scrape loading/dye transfer assay, fluorescence redistribution assay after photobleaching, and immunofluorescent staining of connexin 43 using a laser confocal microscope. The inhibition of GJIC by TPA and H(2)O(2) was prevented with treatment of Rb(2) or EC. The effect of EC on GJIC was stronger in TPA-treated cells than in H(2)O(2)-treated cells, while the effect of Rb(2) was opposite to that of EC. EC, at the concentration of 27.8 microg/ml, prevented the TPA-induced GJIC inhibition by about 60%. Rb(2,) at the concentration of 277 microg/ml, recovered the H(2)O(2)-induced GJIC inhibition by about 60%. These results suggest that Rb(2) and EC may prevent human cancers by preventing the down-regulation of GJIC during the cancer promotion phase and that the anticancer effect of green tea and Korea ginseng may come from the major respective components, EC and Rb(2).

Lack of adverse effects in the F1 offspring maternally exposed to genistein at human intake dose level

Recently there has been growing concern about endocrine disrupters (ED) derived from synthetic and natural chemicals. It has been argued that ED might cause developmental disorders in the next generations of animals and humans; however, this is still unclear. Therefore, we investigated whether maternal exposures to genistein (GEN) during gestation and lactation alter reproductive organs in the F1 offspring compared with those in 17beta-estradiol (E2)-maternally exposed F1 offspring. Pregnant Sprague-Dawley rats were treated orally with 0.4 mg/kg, 4.0 mg/kg GEN or 10 microg/kg E2. Maternal or neonatal effects on the number of live pups, implantation sites, sex ratio, anogenital distance, eyelid opening/vaginal opening and body weight of live pups were not altered by GEN or E2. The weights of reproductive organs at the adult stage F1 offspring were not altered by maternal exposure to GEN, except for the ventral prostate. However, the weight of the seminal vesicle was significantly decreased from postnatal day (PND) 21 to PND 70 in E2-treated offspring. Sperm analyses, cell count in seminiferous tubules and follicular development in the ovary were not altered by maternal exposure to GEN. Taken together, these results suggest that maternal exposure of GEN might not have adverse effects on the reproductive organs in the F1 offspring at the human intake dose level.

Rat pancreatitis produced by 13-week administration of zinc oxide nanoparticles: biopersistence of nanoparticles and possible solutions

Zinc oxide (ZnO) nanoparticles (NPs) are used in diverse applications ranging from paints and cosmetics to biomedicine and food. Although micron‐sized ZnO is a traditional food supplement, ZnO NPs are an unknown public health risk because of their unique physicochemical properties. Herein, we studied the 13‐week subchronic toxicity of ZnO NPs administered via the oral route according to Organization for Economic Cooperation and Development (OECD) test guideline 408. Well‐dispersed ZnO NPs were administered to Sprague–Dawley (SD) rats (11/sex/group) at doses of 67.1, 134.2, 268.4 or 536.8 mg kg–1 per body weight over a 13‐week period. The mean body weight gain in males given 536.8 mg kg–1 ZnO NPs was significantly lower than that of control male rats, whereas no significant differences were observed between the other treatment groups and the controls. Male and female rats dosed at 536.8 mg kg–1 ZnO NPs had significant changes in anemia‐related hematologic parameters. Mild to moderate pancreatitis also developed in both sexes dosed at 536.8 mg kg–1, whereas no histological changes were observed in the other treatment groups. To evaluate the mechanism of toxicity, we performed a bio‐persistence study and evaluated the effects of the ZnO NPs on cell proliferation. The treatment of a human gastric adenocarcinoma cell line with ZnO NPs resulted in a significant inhibition of cellular proliferation. The anti‐proliferative effect of ZnO NPs or Zn2+ was effectively blocked by treatment with chelators. These results indicate that the bio‐persistence of ZnO NPs after ingestion is key to their toxicity; the no‐observed‐adverse effect level (NOAEL) of ZnO NPs was found to be 268.4 mg kg–1 per day for both sexes. Copyright

Genotoxicity of drinking water from three Korean cities

Organic content of drinking tap water from Seoul, Taejon, and Suwon was extracted with an XAD-2 resin column and organic solvents. Four doses of the extract equivalent to 4, 2, 1, and 0.5 l water were tested for mutagenicity in Salmonella typhimurium strains TA98 and TA100 in the presence and absence of S9 mix. The organic extracts of the water from all three cities were mutagenic in TA 98 without S9 mix and in TA 100 with and without S9 mix. The highest number of revertants per plate was found in the absence of S9 mix. Three doses of the extract (equivalent to 22, 11, and 3.7 l water) were also tested in the bone marrow micronucleus test using BDF1 mice. At the highest dose, a significant increase of the micronucleus frequency was observed. The time required to be on the effect, however, varied with the source of the water. Our results indicate that the drinking tap waters from the three cities were genotoxic clearly in the bacterial test and also in the in vivo assay with mice. As we found no genotoxicity of the source water as seen in a previous study, it is likely that the chlorination process leads to the genotoxicity of the tap water.

Safety evaluation of Angelica gigas: Genotoxicity and 13-weeks oral subchronic toxicity in rats

As a well-known traditional medicine, Angelica gigas (AG) and its active constituents, including decursin and decursinol, have been shown to possess several health beneficial properties such as anti-bacterial, immunostimulating, anti-tumor, neuroprotective, anti-nociceptive and anti-amnestic activities. However, there is lack of toxicity studies to assess potential toxicological concerns, especially long-term toxicity and genotoxicity, regarding the AG extract. Therefore, the safety of AG extract was assessed in subchronic toxicity and genotoxicity assays in accordance with the test guidelines published by the Organization for Economic Cooperation and Development. In a subchronic toxicity study for 13 weeks (125, 250, 500, 1000 and 2000 mg/kg body weight, delivered by gavage), data revealed no significant adverse effects of the AG extract in food consumption, body weight, mortality, hematology, biochemistry, necropsy, organ weight and histopathology throughout the study in male and female rats. These results suggest that no observed adverse effect level of the AG extract administered orally was determined to be greater than 2000 mg/kg/day, the highest dose tested. In addition, a battery of tests including Ames test, in vitro chromosome aberration assay and in vivo micronucleus assay suggested that the AG extract was not genotoxic. In conclusion, the AG extract appears to be safe as a traditional medicine for oral consumption.

Robust size control of bovine serum albumin (BSA) nanoparticles by intermittent addition of a desolvating agent and the particle formation mechanism

In polymeric nanoparticle preparation, despite similar conditions, large fluctuations in particle size distributions are usually observed. Herein, we demonstrate that the intermittent addition of a desolvating agent can improve reproducibility in the preparation of polymeric bovine serum albumin (BSA) nanoparticles. Using this modification, BSA nanoparticles of controlled size can be manufactured with narrow particle size distributions. In our study, ethanol as a desolvating agent was added intermittently to 1% BSA solutions at different pHs with stirring at 700rpm. The effect of the preparation parameters on size and optical density of the fabricated nanoparticles were studied. The average particles sizes of BSA nanoparticles prepared at pH values of 6, 7 and 9 were approximately 100, 200 and 300nm, respectively. As ethanol addition increased, desolvation of BSA molecules resulted in formation of loose-structured particles with pH-dependent size. Beyond that, only particle density increased, but size remained unchanged with further addition of ethanol. Consistently uniform particle size distribution was achieved by adding ethanol intermittently.

Comparative toxicity of silicon dioxide, silver and iron oxide nanoparticles after repeated oral administration to rats.

Although silicon dioxide (SiO2), silver (Ag) and iron oxide (Fe2O3) nanoparticles are widely used in diverse applications from food to biomedicine, in vivo toxicities of these nanoparticles exposed via the oral route remain highly controversial. To examine the systemic toxicity of these nanoparticles, well‐dispersed nanoparticles were orally administered to Sprague–Dawley rats daily over a 13‐week period. Based on the results of an acute toxicity and a 14‐day repeated toxicity study, 975.9, 1030.5 and 1000 mg kg–1 were selected as the highest dose of the SiO2, Ag and Fe2O3 nanoparticles, respectively, for the 13‐week repeated oral toxicity study. The SiO2 and Fe2O3 nanoparticles did not induce dose‐related changes in a number of parameters associated with the systemic toxicity up to 975.9 and 1000 mg kg–1, respectively, whereas the Ag nanoparticles resulted in increases in serum alkaline phosphatase and calcium as well as lymphocyte infiltration in liver and kidney, raising the possibility of liver and kidney toxicity induced by the Ag nanoparticles. Compared with the SiO2 and Fe2O3 nanoparticles showing no systemic distribution in all tissues tested, the Ag concentration in sampled blood and organs in the Ag nanoparticle‐treated group significantly increased with a positive and/or dose‐related trend, meaning that the systemic toxicity of the Ag nanoparticles, including liver and kidney toxicity, might be explained by extensive systemic distribution of Ag originating from the Ag nanoparticles. Our current results suggest that further study is required to identify that Ag detected outside the gastrointestinal tract were indeed a nanoparticle form or ionized form. Copyright

Impairment of male rat reproductive function in F1 offspring from dams exposed to 2-bromopropane during gestation and lactation

The toxic effects of 2-bromopropane (2-BP) on the reproductive tracts of male F1 offspring from dams exposed to 2-BP during gestation and lactation were investigated. Ten pregnant (sperm-positive) Sprague-Dawley rats per group were exposed sc to 2-BP at 135, 405, and 1215 mg/kg/day from gestation day (GD) 6 to postnatal day (PND) 20. 2-BP decreased the proportion of dams littering at the two highest doses. At the highest dose, the rate of delivery and surviving pups were significantly lower than in the controls (P < or = 0.05). The relative weights of testes vs. brain were significantly lower than the controls (P < or = 0.05) on PND 33 and 63 at 405 mg/kg/day, and on PND 90 at 1215 mg/kg/day in the F1 rats. Seminiferous tubule atrophy, germ cell loss, and increased Leydig cell proliferation were observed at the highest dose by histopathologic examination. Female offspring has a decrease in all follicle types at the high dose. These results suggest that gestational and lactational exposure to 2-BP at a high maternally toxic dose impairs the development of the reproductive organs of the offspring.

Evaluation of subchronic (13week) toxicity and genotoxicity potential of vinegar-processed Genkwa Flos.

Genkwa Flos (GF) is a well-known traditional medicine that is used to treat tumors and to relieve inflammation-related symptoms. GF tends to be taken in repeated doses for a long period of time, and although many reports on the toxicity of raw GF have led to a processing method to remove the toxicity, little information is currently available with regards to the toxic effects of subchronic exposure to processed GF (PGF). The aim of this study was to assess the possible genotoxicity and subchronic toxicity of PGF extract in accordance with the test guidelines published by the Organization for Economic Cooperation and Development. A 13-week repeat-dose oral toxicity study was carried out with rats, and the change in body weight observed in rats receiving PGF extract was normal. It is worth noting that the PGF extract groups exhibited an obvious increase in liver weight along with a significant increase in serum alkaline phosphatase activity at doses of 667 and 2000mg/kg, providing evidence of hepatotoxic potential. More importantly, the results of the Ames test indicated that the PGF extract presented a mutagenic potential. Altogether, these results are the first to determine the subchronic toxicity and genotoxicity of the PGF extract, indicating that when GF is used for medicinal purposes, the period of use should be considered despite the manner in which the extract is processed.

Genotoxicity and subchronic toxicity of Sophorae radix in rats: hepatotoxic and genotoxic potential.

Although Sophorae radix (SR) has been traditionally used as a treatment for various clinical symptoms, a comprehensive investigation of its safety has not yet been carried out. Therefore, we present an evaluation of the toxicity of the SR extract that was performed according to the Organization for Economic Cooperation and Development test guidelines for subchronic toxicity and genotoxicity. In an oral subchronic study for 13 weeks, the repeated treatment of rats with 429 or 1500 mg/kg of the SR extract induced a dose-related change in body weight. In particular, the SR extract was observed to exert a significant increase in liver weight along with an increase in serum alkaline phosphatase and alanine transaminase. A small but statistically significant reductions in red blood cell, hemoglobin, and hematocrit levels in the SR extract-treated rats suggest the possibility that anemia, accompanied by liver injury, was at least partially induced. These findings indicate the no-observed-adverse-effect-level for the SR extract was considered to be 10mg/kg/d. And, the data obtained from the chromosome aberration assay showed that SR extract might be considered to be a weak clastogen although no significant micronucleus induction was observed in vivo. Despite the benefits that SR extract can exhibit, this study indicates that SR extract may possess hepatotoxic and genotoxic potential.