In vitro antimutagenicity of capsaicin toward heterocyclic amines in Salmonella typhimurium strain TA98.
(65/241)
Capsicum fruits are widely consumed as a component of the human diet. Capsaicin is the principle substance responsible for their hot, pungent taste. Heterocyclic amines (HCAs) are formed during cooking of meats and are mutagenic/carcinogenic compounds. In this study, we looked at whether capsaicin showed anti-mutagenic effects toward HCA-induced mutagenesis in Salmonella typhimurium TA98 when incubated with 0.5 mg liver S9 protein from rat, hamster and human. The HCAs used were Trp-P-2, Glu-P-1 and PhIP. Capsaicin, at non-toxic amounts of 0.25 and 0.5 micromole/plate, expressed a dose-dependent inhibition of the mutagenicity of Glu-P-1 and PhIP when they are metabolically activated by rat, hamster and human liver S9 and of Trp-P-2 when activated by rat and hamster liver S9. In contrast, capsaicin enhanced the mutagenicity of Trp-P-2 in TA98 when incubated with human liver S9. The lack of consistency in the anti-mutagenic action of capsaicin toward HCAs is puzzling and currently unresolved. (+info)
Antigenotoxic and antimutagenic potential of an annatto pigment (norbixin) against oxidative stress.
(66/241)
Carotenoids are 40-carbon molecules with conjugated double bonds, making them particularly effective for quenching free radicals. They have always been believed to possess anticancer properties, which could be due to their antioxidant potential. Norbixin is an unusual dicarboxylic water-soluble carotenoid present as a component in the pericarp of the seeds of Bixa orellana L. (from the Bixaceae family), a tropical shrub commonly found in Brazil. The main carotenoids present in these seeds, bixin and norbixin, form a coloring material, known as annatto, which is mainly used in the food industry. As annatto is only used as a coloring material, most studies of annatto pigments have focused on the determination of annatto levels in food. However, little attention has been given to the biological properties of bixin and norbixin. We evaluated the effect of norbixin on the response of Escherichia coli cells to DNA damage induced by UV radiation, hydrogen peroxide (H2O2) and superoxide anions (O2*-)) and found that norbixin protects the cells against these agents. Norbixin enhanced survival at least 10 times. The SOS induction by UVC was inhibited 2.3 times more when cells were grown in the presence of norbixin. We also found that norbixin has antimutagenic properties, with a maximum inhibition of H2O2-induced mutagenic activity of 87%, based on the Salmonella mutagenicity test. (+info)
Antimutagenic constituents from the thorns of Gleditsia sinensis.
(67/241)
Antimutagenic activity-guided fractionation of an extract prepared from the thorns of Gleditsia sinensis LAM. led to the isolation of one triterpenoid and four steroids, which were identified as D:C-friedours-7-en-3-one (1), stigmast-4-ene-3,6-dione (2), stigmastane-3,6-dione (3), stigmasterol (4), and beta-sitosterol (5). Triterpenoid 1 was found for the first time in a natural source and the steroids 2-5 were first isolated from this plant. Stigmasterol was the most active antimutagen, showing 51.2% and 64.2% reduction of the induction factor against the mutagens MNNG and NQO, respectively, in the SOS chromotest. Some NMR data of the steroids 2 and 3 obtained have to be revised. (+info)
DPPH radical-scavenging compounds from dou-chi, a soybean fermented food.
(68/241)
Dou-chi, a traditional soybean food fermented with Aspergillus sp., is usually used as a seasoning in Chinese food, and has also been used as a folk medicine in China and Taiwan. As 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavengers, four phenol compounds, one isoflavanone, eight isoflavones and one 4-pyrone have been isolated from dou-chi. Among these fourteen compounds, 3'-hydroxydaidzein, dihydrodaidzein and a 4-pyrone compound have not yet been isolated from soybean miso. The structure of the novel 4-pyrone compound, 3-((E)-2-carboxyethenyl)-5-(4-hydroxyphenyl)-4-pyrone-2-carboxylic acid was elucidated by using the same compound as that obtained from the biotransformation of daidzein. 3'-Hydroxydaidzein showed as high DPPH radical-scavenging activity as that of alpha-tocopherol, and 6-hydroxydaidzein had mushroom tyrosinase inhibitory activity with an IC(50) value of 10 muM. The order of estrogenic activity is as follows: genistein > daidzein >> 3'-hydroxydaidzein > 8-hydroxygenistein, using a green fluorescent protein expression system. Furthermore, the contents of isoflavones in the fermentation process of dou-chi were measured. (+info)
Assessment of antioxidant / anticarcinogenic activity of plant extracts by a combination of molecular methods.
(69/241)
Cancer chemoprevention is considered to be a promising approach for cancer control, as it has been identified by both epidemiological and molecular studies that environmental factors are the major causes of cancer. Chemoprevention can be defined as the use of agents to prevent, inhibit or reverse the process of carcinogenesis. Several epidemiological studies have shown that fruits, vegetables and common beverages, as well as herbs and plants, are rich sources of chemopreventive compounds. In the present report, a battery of in vitro methods for the identification of chemopreventive agents are presented. These methods include: i) inhibition of bleomycin-induced mutations in Salmonella typhimurium TA102 cells, ii) inhibition of bleomycin-induced sister chromatid exchanges (SCEs) in human peripheral blood lymphocytes, iii) protection from mitomycin C-induced DNA strand breakage and iv) inhibition of topoisomerase I DNA relaxation. The first three methods are also used for the identification of agents which prevent reactive oxygen species (ROS)-mediated DNA damage. (+info)
Stimulation of human monocyte and polymorphonuclear cell iodination and interleukin-1 production by epigallocatechin gallate.
(70/241)
(-)Epigallocatechin gallate (EGCg) stimulated iodination of human peripheral blood monocytes, polymorphonuclear cells (PMN), and human promyelocytic leukemic HL-60 cells, dependent on time, dose, and temperature. However, EGCg did not affect iodination of nonadherent peripheral blood mononuclear cells, red blood cells, or 11 other cultured cell lines. Although various immunoregulators such as lipopolysaccharide (LPS), opsonized zymosan, 12-O-tetradecanoylphorbol-13-acetate (TPA) and tumor necrosis factor stimulated PMN iodination to varying degrees, their ability to stimulate monocyte iodination was much lower than that of EGCg. Washout experiments demonstrated that contact with EGCg for less than 60 min irreversibly stimulated PMN and monocyte iodination. EGCg also potently stimulated the production of interleukin-1-like factor by monocytes. The data suggest that EGCg is a strong in vitro stimulant of human phagocytes. (+info)
Methylxanthines (caffeine, pentoxifylline and theophylline) decrease the mutagenic effect of daunomycin, doxorubicin and mitoxantrone.
(71/241)
Previously performed experiments showed that methylxanthines, especially caffeine, may protect cells against cytostatic or cytotoxic effects of several aromatic compounds. One of the proposed mechanisms of this protection is based on stacking interactions between pi electron systems of polycyclic aromatic molecules. In this work, we demonstrate that caffeine and other methylxanthines--pentoxifylline and theophylline--significantly decrease mutagenicity of the anticancer aromatic drugs daunomycin, doxorubicin and mitoxantrone. The spectrophotometric titration of these aromatic compounds by methylxanthines indicated formation of mixed aggregates. The concentrations of free active forms of the drugs decreased when the concentrations of methylxanthines increased in the mixture. Therefore, likely methylxanthines may play a role of scavengers of the free active forms of daunomycin, doxorubicin and mitoxantrone. (+info)
Antioxidative and antigenotoxic effects of Japanese horse chestnut (Aesculus turbinata) seeds.
(72/241)
Japanese horse chestnut seed extract (HCSE) dose-dependently inhibited the autooxidation of linoleic acid (IC(50): 0.2 mg/ml), and the inhibition was almost complete at a concentration of 1 mg/ml. The HCSE scavenged DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals and superoxide anions with EC(50)s of 0.65 and 0.21 mg/ml, respectively. However, it had no effect on hydrogen peroxide. The HCSE inhibited the genotoxicities of furylfuramide, N-methyl-N-nitrosourea, methyl methanesulfonate, mitomycin C, 2-aminoanthracene and aflatoxin B1 at a concentration of 1 mg/ml or more. Total polyphenol content of the HCSE was 21 mg/g (13 mg/g-seeds). These results indicate that the Japanese horse chestnut seed is an antioxidative and antimutagenic botanical resource. (+info)