Effect of cyanidin 3-O-beta-glucopyranoside on micronucleus induction in cultured human lymphocytes by four different mutagens

Characterization of benzo[a]pyrene and colchicine based on an in vivo repeat-dosing multi-endpoint genotoxicity quantitative assessment platform

Two prototypical genotoxicants, benzo[a]pyrene (B[a]P) and colchicine (COL), were selected as model compounds to deduce their quantitative genotoxic dose–response relationship at low doses in a multi-endpoint genotoxicity assessment platform. Male Sprague-Dawley rats were treated with B[a]P (2.5–80 mg/kg bw/day) and COL (0.125–2 mg/kg bw/day) daily for 28 days. The parameters included were as follows: comet assay in the peripheral blood and liver, Pig-a gene mutation assay in the peripheral blood, and micronucleus test in the peripheral blood and bone marrow. A significant increase was observed in Pig-a mutant frequency in peripheral blood for B[a]P (started at 40 mg/kg bw/day on Day 14, started at 20 mg/kg bw/day on Day 28), whereas no statistical difference for COL was observed. Micronucleus frequency in reticulocytes of the peripheral blood and bone marrow increased significantly for B[a]P (80 mg/kg bw/day on Day 4, started at 20 mg/kg bw/day on Days 14 and 28 in the blood; started at 20 mg/kg bw/day on Day 28 in the bone marrow) and COL (started at 2 mg/kg bw/day on Day 14, 1 mg/kg bw/day on Day 28 in the blood; started at 1 mg/kg bw/day on Day 28 in the bone marrow). No statistical variation was found in indexes of comet assay at all time points for B[a]P and COL in the peripheral blood and liver. The dose–response relationships of Pig-a and micronucleus test data were analyzed for possible point of departures using three quantitative approaches, i.e., the benchmark dose, breakpoint dose, and no observed genotoxic effect level. The practical thresholds of the genotoxicity of B[a]P and COL estimated in this study were 0.122 and 0.0431 mg/kg bw/day, respectively, and our results also provided distinct genotoxic mode of action of the two chemicals.

Polyphenols as anticancer agents: Toxicological concern to healthy cells

Polyphenols are a group of diverse chemical compounds present in a wide range of plants. Various biological properties such as antiallergic, antiviral, antibacterial, anticarcinogenic, antiinflammatory, antithrombotic, vasodilatory, and hepatoprotective effect of different polyphenols have been reported in the scientific literature. The major classes of polyphenols are flavonoids, stilbenoids, lignans, and polyphenolic acids. Flavonoids are a large class of food constituents comprising flavones, isoflavanones, flavanones, flavonols, catechins, and anthocyanins sub-classes. Even with seemingly broad biological activities, their use is minimal clinically. Among the other concurrent problems such as limited bioavailability, rapid metabolism, untargeted delivery, the toxicity associated with these polyphenols has been a topic of concern lately. These polyphenols have been reported to result in different forms of toxicity that include organ toxicity, genotoxicity, mutagenicity, cytotoxicity, etc. In the present article, we have tried to unravel the toxicological aspect of these polyphenols to healthy cells. Further high-quality studies are needed to establish the clinical efficacy and toxicology concern leading to further exploration of these polyphenols.

Human Amniotic Epithelial Cells as a Tool to Investigate the Effects of Cyanidin 3-O-Glucoside on Cell Differentiation

Cyanidin, a kind of anthocyanin, has been reported to have chemotherapeutic activities in humans. Human amniotic epithelial cells (hAECs) are considered a potential source of pluripotent stem cells. hAECs have been used as a novel tool in regenerative cellular therapy and cell differentiation studies. In this study, to explore the effects of cyanidin-3-O-glucoside (Cy3G) on hAECs and their mechanisms, we investigated the transcriptomic changes in the Cy3G-treated cells using microarray analysis. Among the differentially expressed genes (Fold change > 1.1; p-value < 0.05), 109 genes were upregulated and 232 were downregulated. Ratios of upregulated and downregulated genes were 0.22% and 0.47% of the total expressed genes, respectively. Next, we explored the enriched gene ontology, i.e., the biological process, molecular function, and cellular component of the 37 upregulated (>1.3-fold change) and 124 downregulated (<1.3-fold change) genes. Significantly enriched biological processes by the upregulated genes included “response to muscle activity,” and the genes involved in this gene ontology (GO) were Metrnl and SRD5A1, which function in the adipocyte. On the other hand, the cell cycle biological process was significantly enriched by the downregulated genes, including some from the SMC gene family. An adipogenesis-associated gene DDX6 was also included in the cell cycle biological process. Thus, our findings suggest the prospects of Cy3G in modulating adipocyte differentiation in hAECs.

Metabolomic Profiling of the White, Violet, and Red Flowers of Rhododendron schlippenbachii Maxim

Rhododendron schlippenbachii Maxim. is a garden plant that is also used for natural medicines as a consequence of the biological activities of its diverse metabolites. We accordingly profiled two anthocyanins and 40 primary and secondary metabolites in the three different colored flowers. The major anthocyanins found in the flowers were cyanidins. The red flowers exhibited the highest accumulation of anthocyanins (1.02 ± 0.02 mg/g dry weight). Principal component analysis was applied to the GC‒TOFMS data. The levels of key tricarboxylic acid cycle intermediates in red flowers, such as succinic acid, fumaric acid, and malic acid, were found to be highly significantly different (p < 0.0001) from those in the flowers of other colors. In this study, we aimed to determine metabolite interactions and phenotypic variation among white, violet, and red flowers of R. schlippenbachii by using gas chromatography time-of-flight mass spectrometry (GC‒TOFMS) and high-performance liquid chromatography (HPLC).

Intake of anthocyanidins pelargonidin and cyanidin reduces genotoxic stress in mice induced by diepoxybutane, urethane and endogenous nitrosation

Pelargonidin (PEL) and cyanidin (CYN) are among the six most abundant anthocyanidins which provide red, blue and purple colors to fruits and vegetables. Health benefits associated with intake of anthocyanins have been attributed mainly to antioxidant activity of these color pigments. The aim of our present study was to assess in mice the impact of PEL and CYN intake on genotoxic stress induced by DNA damaging environmental toxicants. These anthocyanidins were administered by gavage to mice before exposure to genotoxic carcinogens diepoxybutane (DEB) and urethane (URE). In addition, the inhibitory effect of PEL and CYN on endogenous nitrosation was evaluated by using a model nitrosation reaction mixture consisting of methyl urea (MU)+sodium nitrite (SN) which reacts in the stomach to form the carcinogenic methyl nitrosourea (MNU). All the test doses of PEL (2.5-20 mg/kg) and CYN (1-4 mg/kg) significantly reduced the genotoxicity of DEB. A dose-related increase was observed for antigenotoxicity of PEL against URE. The lowest test-dose of CYN showed maximum protection against URE. Co-administration of PEL/CYN with the nitrosation reaction mixture led to reduction in genotoxicity. CYN was more effective as an inhibitor of endogenous nitrosation. Combination of PEL with ascorbic acid (AA) enhanced the antinitrosating effect when compared to that with each phytochemical alone. The results of our present study indicate that common anthocyanidins PEL and CYN can play a major role in reducing genotoxic stress induced by environmental toxicants.

Modulation of radiation-induced and mitomycin C-induced chromosome damage by apigenin in human lymphocytes in vitro

Apigenin (APG), a flavone, is known to exhibit antioxidant, antimutagenic and antitumorigenic activity, both in vivo and in vitro. The aim of this study is to investigate the modulatory effects of APG on human lymphocytes after irradiation with gamma rays (3 Gy) or treatment with the antineoplastic agent, mitomycin C (MMC), in vitro. Cytogenetic biomarkers such as chromosome aberrations (CAs), sister chromatid exchanges (SCEs) and cytochalasin-B blocked micronuclei (CBMN), were studied in blood lymphocytes treated with radiation, or antineoplastic agent (MMC), and APG. Whole blood lymphocytes were cultured in vitro using a standard protocol. No significant differences were found in the frequency of CAs or micronuclei (MN) in human peripheral blood lymphocytes irradiated with gamma rays (3 Gy) and then post-treated with APG. There was an increase in the frequency of SCEs per cell in APG-treated samples compared with the controls. Lymphocytes treated with MMC in the presence of APG exhibited a significant decrease (P < 0.01) in the frequency of SCEs compared with MMC treatment alone. The data for the MN test indicated that APG treatment significantly reduced (P < 0.01) the frequency of MMC-induced MN.

Antigenotoxic effect of apigenin against anti-cancerous drugs

Mitomycin C and cyclophosphamide are well known anti-tumor drugs. Their genotoxic effects are well established in various test systems. The genotoxic effects in non-tumor cell are of special significance due to the possibility that they may induce secondary tumors in cancer patients. Apigenin is a well known anti-oxidant and possess number of properties that are beneficial in some way to humans. With this view, the present study deals with the effect of apigenin against the genotoxic doses of mitomycin C and cyclophosphamide using chromosomal aberrations, sister chromatid exchanges and cell cycle kinetics as a parameters. The treatment of apigenin results in a significant, dose dependent decrease in the genotoxic damage, induced by mitomycin C and cyclophosphamide. It is concluded that the apigenin is potent in reducing the genotoxic damage, induced by anti-cancerous drugs, thereby reducing the chances of developing secondary tumors during the therapy.

Antigenotoxic effects of the phytoestrogen pelargonidin chloride and the polyphenol chlorogenic acid

Pelargonidin (PEL), a common anthocyanidin with estrogenic activity, was tested in HL-60 cells for its genotoxicity and possible antigenotoxic effects against 4-nitroquinoline 1-oxide (NQO), a potent mutagen and carcinogen which induces oxidative stress. To take into account potential interactions between phytochemicals within normal human nutrition, we evaluated a combination of PEL with the nonestrogenic phytochemical chlorogenic acid (CLA), one of the most abundant polyphenols in the human diet. PEL (< or = 2 microM) and CLA (< or = 800 microM) were nongenotoxic in the micronucleus test. We observed significant antigenotoxic effects against NQO with both compounds, but no additive interaction of PEL and CLA. Comet assay results showed a nonsignificant reduction in NQO-induced DNA damage with both compounds and their combination. Flow cytometric analysis of oxidative stress revealed significant protection against NQO-induced oxidative stress by PEL, CLA, and their combination. Furthermore, PEL and CLA prevented the NQO-induced reduction in GSH level. This could be a mechanism for the observed reduction in genotoxicity. In conclusion, the phytoestrogen PEL revealed antioxidative and antigenotoxic properties in HL-60 cells, but no significant additive interaction with the abundant nutritional polyphenol CLA under the tested conditions.

Evaluation of apigenin using in vitro cytochalasin blocked micronucleus assay

High doses of flavonoids are reported to be clastogenic in contrast to their potential to reduce oxidative DNA damage, retard growth of leukemia cells, obstruct cell signal transduction and induce cellular differentiation in cancers. In the present study, we evaluated apigenin, a plant-derived flavonoid in doses of 10, 33, and 100 microM per 5 ml culture using cytochalasin-B blocked micronucleus (CBMN) assay in peripheral human lymphocytes. Apigenin was found to induce micronuclei in a dose dependent manner indicating potential genotoxic hazard in humans. Hence, flavonoids may act as mutagen, pro-oxidant or as inhibitor of key enzymes to produce clastogenic effects depending upon the levels consumed as well as the physiological parameters.

Anthocyans from fruits and vegetables – Does bright colour signal cancer chemopreventive activity?

Consumption of fruits and berries has been associated with decreased risk of developing cancer. The most abundant flavonoid constituents of fruits and berries are anthocyans (i.e. anthocyanins, glycosides, and their aglycons, anthocyanidins) that cause intense colouration. In this review, we describe epidemiological evidence hinting at the cancer preventive activity of anthocyan-containing foods in humans, results of chemoprevention studies in rodent models with anthocyans or anthocyan-containing fruit/vegetable extracts, and pharmacological properties of anthocyans. Anthocyanidins have been shown to inhibit malignant cell survival and confound many oncogenic signalling events in the 10(-6)-10(-4) M concentration range. Studies of the pharmacokinetics of anthocyanins after their consumption as single agents, anthocyanin mixtures or berry extracts suggest that anthocyanins reach levels of 10(-8)-10(-7) M in human blood. It is unclear whether such concentrations are sufficient to explain anticarcinogenic effects, and whether anthocyanins exert chemopreventive efficacy themselves, or if they need to undergo hydrolysis to their aglyconic counterparts. The currently available literature provides tantalising hints of the potential usefulness of anthocyans or anthocyan mixtures as cancer chemopreventive interventions. Nevertheless further studies are necessary to help adjudge the propitiousness of their clinical development.

Genotoxicity of phytoestrogens

Plant extracts containing phytohormones are very popular as 'alternative' medicine for many kinds of diseases. They are especially favored by women who enter menopause and are concerned about the side effects of hormone replacement therapy. However, adverse health effects of phytoestrogens have often been ignored. This review examines the literature on genotoxicity and apoptotic effects of phytohormones. Genistein, coumestrol, quercetin, zearalenone, and resveratrol exerted genotoxic effects in in vitro test systems. Other phytoestrogens such as lignans, the isoflavones daidzein and glycetein, anthocyanidins, and the flavonol fisetin exhibited only weak or no effects in vitro. However, some metabolites of daidzein showed a genotoxic activity in vitro. Practically all of the phytoestrogens exhibit pro-apoptotic effects in some cell systems. Further investigations regarding dose-response-relationships and other aspects relevant for extrapolation to human exposure seem necessary. Until then, care may be advised in taking concentrated phytohormones. Nevertheless, the intake of substantial amounts of plant-food in a normal diet constitutes an important, individual contribution to cancer prevention.

Micronucleus formation and induction of apoptosis by different isothiocyanates and a mixture of isothiocyanates in human lymphocyte cultures

Isothiocyanates (ITCs) are the main sulfur-containing metabolites found in cruciferous vegetables. There is evidence that some ITCs may act as chemopreventive agents against different tumor types and induce apoptosis and modulate cell-cycle progression of highly proliferative cancer cells. However, there are also studies reporting genotoxic or co-carcinogenic effects for some ITCs, such as benzyl ITC and phenyl ITC. Since selectivity for transformed cells and absence of genotoxicity for healthy cells are important pre-requisites for new chemopreventive agents, we investigated micronucleus formation and induction of apoptosis by 4-(methylthio)butylisothiocyanate (MTBITC), sulforaphane and a mixture of ITCs in human T-lymphocyte cultures. We demonstrate that MTBITC, sulforaphane and the mixture of ITCs did not induce micronuclei. Moreover, sulforaphane induced a dose-dependent increase in the number of apoptotic cells, which was significant at the highest concentration tested (30 microM) (41% versus 18% in the untreated samples, P<0.05). The mixture of ITCs presented a trend similar to that found for sulforaphane. In fact, the mixture of ITCs was able to induce a dose-dependent increase in the percentage of apoptotic cells, which reached a maximum value at the concentration of 13 microg/ml (46% versus 19% in control samples, P<0.05). Induction of apoptosis was not observed in cultures treated with MTBITC. Our results suggest that different ITCs can have different effects. Moreover, although the mixture of glucosinolates (GLs) used in the present study does not reflect the exact composition of broccoli, our findings demonstrate that the quantitative effects of a single, specific ITC can be significantly different from those of an ITC mixture, where other ITCs of the mixture contribute to the outcome observed.