Interventive prophylaxis of liver cancer

Antioxidant Activity and Inhibitory Potential of Cistus salviifolius (L.) and Cistus monspeliensis (L.) Aerial Parts Extracts against Key Enzymes Linked to Hyperglycemia

Cistus genus (Cistaceae) comprises several medicinal plants used in traditional medicines to treat several pathological conditions including hyperglycemia. These include Cistus salviifolius L. (CS) and Cistus monspeliensis L. (CM), still not fully explored as a source of metabolites with therapeutic potential for human diseases. In this study, the antioxidant α-amylase and α-glucosidase enzyme inhibitory effects of aqueous and hydromethanolic extracts from the aerial parts of Moroccan CS and CM were investigated. Antioxidant activity has been assessed using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radicals and ferric reducing/antioxidant power (FRAP) methods. The α-amylase and α-glucosidase inhibitory activity has been assessed using an in vitro model. Moreover, mineral and phenolic contents of CS and CM were analyzed. The extracts of both species exhibited potent antioxidant activity in all used systems and possess strong inhibitory effect towards α-glucosidase (IC₅₀: 0.95 ± 0.14 to 14.58 ± 1.26 μg/mL) and significant inhibitory potential against α-amylase (IC₅₀: 217.10 ± 0.15 to 886.10 ± 0.10 μg/mL). Furthermore, the result showed high levels of phenolic content and unexpectedly some higher levels of mineral content in CS. The results suggest that the phenolic rich extracts of CS and CM may have a therapeutic potential against diseases associated with oxidative stress and may be useful in the management of hyperglycemia in diabetic patients.

Phytochemicals as potential chemopreventive and chemotherapeutic agents in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is the fifth commonest malignancy worldwide and the incidence is rising. Surgery, including transplantation resection, is currently the most effective treatment for HCC; however, recurrence rates are high and long-term survival is poor. Identifying novel chemopreventive and chemotherapeutic agents and targeting them to patients at high risk of developing HCC or following curative treatment may go some way towards improving prognosis. This review examines current knowledge regarding the chemopreventive and chemotherapeutic potential of phytochemicals in heptocarcinogenesis. Both in-vitro and animal studies demonstrate that several phytochemicals, including curcumin, resveratrol, green tea catechins, oltipraz and silibinin, possess promising chemopreventive and chemotherapeutic properties. Despite this, very few clinical trials have been performed. Problems regarding validation of biomarkers, agent delivery, side effects and patient selection are barriers that need to be overcome to determine the potential of such agents in clinical practice.

Effects of Sho-Saiko-to on hepatocarcinogenesis and 8-hydroxy-2'-deoxyguanosine formation

Oxidative stress plays an important role in hepatocarcinogenesis. Although Sho-saiko-to (TJ-9), a Japanese herbal medicine which has been recently administered to patients with chronic liver disease in Japan, prevents hepatocarcinogenesis, the mechanism by which TJ-9 protects against cancer development is not fully understood. 8-Hydroxy-2'-deoxyguanosine (8-OHdG), a DNA adduct by reactive oxygen species, is known as a parameter of genetic risk for hepatocarcinogenesis. To clarify whether the preventive effect on hepatocarcinogenesis by TJ-9 is dependent on 8-OHdG, the effect on 8-OHdG levels by TJ-9 was examined by using high-performance liquid chromatography-mass spectrometry (LC-MS) in a diethylnitrosamine (DEN)-induced hepatocarcinogenesis model of male Fisher rats. TJ-9 reduced the number of preneoplastic cells, detected as the glutathione S transferase P (GST-P)-positive hepatocytes, and inhibited the development of liver tumors. TJ-9 also significantly decreased the formation of 8-OHdG, as indicated by LC-MS and immunohistochemical analysis. In addition, ornithine decarboxylase (ODC) activity and the number of proliferating cell nuclear antigen (PCNA)-positive cells were not altered. An electron paramagnetic resonance spin-trapping technique showed that TJ-9 scavenges hydroxyl radicals in a dose-dependent manner. In conclusion, the results of the present study suggest that TJ-9 prevents hepatocarcinogenesis in association with inhibition of 8-OHdG formation.

Analysis of the antioxidant butylated hydroxytoluene (BHT) in water by means of solid phase extraction combined with GC/MS

The antioxidant 3,5-di-tert-butyl-4-hydroxy-toluene (BHT) is widely used as an additive to increase the tenability of food and plastics. BHT is degraded to 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO) in mammals, as well as in the natural environment such as in water and soils. BHT-CHO has been studied extensively in terms of their potential toxicities. The present investigation was carried out to quantify BHT and BHT-CHO in river, ground, rain and drinking water obtained from several locations in Germany. Apart from the compounds mentioned above, 1,2-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)ethane (2-BHT), which is a dimer of BHT, was also detected in the extracts of some ground water samples. The applied analytical method is based on solid phase extraction (SPE) to concentrate trace compounds from water samples followed by gas chromatography/mass spectrometry (GC/MS) of the extracts. A total of 51 of the respective water samples were used for extraction purposes and analyte recoveries were all > or = 80%. The determination limit for BHT was 5 ng l(-1) and for BHT-CHO 16 ng l(-1). The standard deviations for the analytical procedure were 6% for BHT and 10% for BHT-CHO. The use of the antioxidant BHT in Germany has resulted in water concentrations of 7-791 ng l(-1) in the rivers Rhine, Elbe, Main, Oder, Nidda and Schwarzbach. The degradation product BHT-CHO was also detected in the river water samples at concentrations between 29 and 223 ng l(-1). The concentrations of BHT measured in German rivers are lower compared to values measured in the USA and Japan 20 years ago. In ground water, levels for BHT varied from non-detectable up to 2156 ng l(-1) and for BHT-CHO from non-detectable up to 674 ng l(-1). Both compounds were also detected in rain water in Frankfurt/Main at a concentration of 1797 ng l(-1) for BHT and 59 ng l(-1) for BHT-CHO.

Suppression by Chai-hu-gui-zhi-tang of the development of liver lesions induced by N-nitrosomorpholine in Sprague-Dawley rats

The effects of Chai-hu-gui-zhi-tang (TJ-10) on the development of liver lesions induced by N-nitrosomorpholine and on labeling and apoptotic indices were investigated in male Sprague-Dawley rats. Rats were given chow pellets containing 0.5 or 1.0% TJ-10 and, from the beginning of the experiment, were given drinking water containing N-nitrosomorpholine for 8 weeks. Visible white liver nodules, cellular alteration foci, and hepatic foci staining positively for glutathione-S-transferase, placental type, were examined macroscopically or histochemically. In week 16, TJ-10 at both dosages significantly reduced the incidence, and/or number of visible white nodules and hepatic lesions. Quantitative histologic analysis also showed that prolonged feeding of TJ-10 at both dosages significantly reduced the number of hepatic foci positive for glutathione-S-transferase, placental type. Administration of TJ-10 at both dosages also significantly decreased the labeling index of adjacent liver and significantly increased the apoptotic index of adjacent liver but had no significant effect on those of neoplastic lesions. These findings indicate that TJ-10 suppresses the development of liver lesions and suggest that this effect might be related to TJ-10's inhibition of cell proliferation and induction of apoptosis in adjacent hepatocytes.

Safety assessment of butylated hydroxyanisole and butylated hydroxytoluene as antioxidant food additives

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are widely used antioxidant food additives. They have been extensively studied for potential toxicities. This review details experimental studies of genotoxicity and carcinogenicity which bear on cancer hazard assessment of exposure to humans. We conclude that BHA and BHT pose no cancer hazard and, to the contrary, may be anticarcinogenic at current levels of food additive use.

Effect of dietary lipid on gamma-glutamyl transferase-positive foci during hepatocarcinogenesis in rats

The effect of dietary lipid on gamma-glutamyl transferase-positive (GGT-positive) foci was investigated. Female Sprague-Dawley rats were dosed with diethylnitrosamine (15 mg/kg) at 24 h of age. After weaning, they were fed nutritionally complete semipurified diets for 3 months. Rats fed 15% corn oil had significantly lower hepatic phospholipid eicosapentaenoate and docosahexaenoate than rats fed 7.5% corn oil plus 7.5% fish oil, 5% corn oil plus 10% fish oil (P < 0.05). However, rats fed 15% corn oil had significantly greater hepatic phospholipid arachidonate than rats fed the other two diets (P < 0.05), suggesting that n-3 polyunsaturated fatty acids were incorporated into hepatic phospholipid at the expense of n-6 polyunsaturated fatty acids. Hepatic PGF2alpha content was significantly greater in rats fed 15% corn oil than in rats fed the other two diets (P < 0.05). Rats fed fish oil had significantly lower hepatic vitamin E content than rats fed corn oil (P < 0.05). Hepatic lipid peroxidation (TBARS) tended to increase with increased dietary fish oil (P < 0.05). Dietary lipid did not influence GGT-positive foci area or number. In conclusion, dietary lipid affected hepatic PGF2alpha production, however, showed no effect on GGT-positive foci area and number. This may suggest that PGF2alpha is not the underlying mechanism for GGT-positive foci during hepatocarcinogenesis.

Chemicals with carcinogenic activity in the rodent liver; mechanistic evaluation of human risk

A wide variety of chemicals, both naturally occurring and synthetic, have exhibited carcinogenic activity in rodent liver. Some are clearly DNA reactive whereas others produce only epigenetic effects. Hepatocarcinogens are categorized according to these properties and the characteristics of examples of both types are reviewed. DNA-reactive rodent hepatocarcinogens represent human cancer risk even at non-toxic exposures, whereas epigenetic agents pose either no risk because their effects are specific to rodents, or a risk only at high exposures at which they produce the same cellular effects in humans that are the basis for their carcinogenic activity in rodents.

Inhibition of the hepatocarcinogenicity of aflatoxin B1 in rats by low levels of the phenolic antioxidants butylated hydroxyanisole and butylated hydroxytoluene

The phenolic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were studied for inhibition of aflatoxin B1 (AFB1) hepatocarcinogenesis in male Fischer 344 rats. The antioxidants were administered at 5, 25, or 125 ppm in AIN-76A diet for 42 weeks. Beginning with week 2, 5 micrograms/kg of AFB1 was given by intragastric instillation three times a week for 40 weeks either alone or concurrently with BHA or BHT feeding. The development of hepatocellular altered foci (HAF) induced by AFB1, as indicators of hepatocarcinogenesis, was monitored using immunohistochemical staining for the placental form of glutathione S-transferase. By 16 weeks the multiplicity of foci was 1.97/cm2 of liver area in rats given only AFB1, and this increased to 4.11/cm2 at 24 weeks and to 10.60/cm2 at 32 weeks. At the final sacrifice at 42 weeks, the multiplicity of foci was 12.90/cm2 compared to 0.75/cm2 in untreated controls. In rats given antioxidants in addition to AFB1, the high dose of BHA reduced the multiplicity to 7.72/cm2 and the high dose of BHT reduced the multiplicity to 9.35/cm2. Lower levels did not reduce foci induction. Thus, in male rats under the conditions of this experiment, the level of 125 ppm of either BHA or BHT inhibited the initiation of hepatocarcinogenesis by AFB1. The BHA effect was slightly greater than that of BHT.