Prooxidant DNA breakage induced by caffeic acid in human peripheral lymphocytes: Involvement of endogenous copper and a putative mechanism for anticancer properties

Exploring the Multi-Faceted Potential of Carob (Ceratonia siliqua var. Rahma) Leaves from Morocco: A Comprehensive Analysis of Polyphenols Profile, Antimicrobial Activity, Cytotoxicity against Breast Cancer Cell Lines, and Genotoxicity

The botanical species Ceratonia siliqua L., commonly referred to as the Carob tree, and locally as "L'Kharrûb", holds significance as an agro-sylvo-pastoral species, and is traditionally utilized in Morocco for treating a variety of ailments. This current investigation aims to ascertain the antioxidant, antimicrobial, and cytotoxic properties of the ethanolic extract of C. siliqua leaves (CSEE). Initially, we analyzed the chemical composition of CSEE through high-performance liquid chromatography with Diode-Array Detection (HPLC-DAD). Subsequently, we conducted various assessments, including DPPH scavenging capacity, β-carotene bleaching assay, ABTS scavenging, and total antioxidant capacity assays to evaluate the antioxidant activity of the extract. In this study, we investigated the antimicrobial properties of CSEE against five bacterial strains (two gram-positive, Staphylococcus aureus, and Enterococcus faecalis; and three gram-negative bacteria, Escherichia coli, Escherichia vekanda, and Pseudomonas aeruginosa) and two fungi (Candida albicans, and Geotrichum candidum). Additionally, we evaluated the cytotoxicity of CSEE on three human breast cancer cell lines (MCF-7, MDA-MB-231, and MDA-MB-436) and assessed the potential genotoxicity of the extract using the comet assay. Through HPLC-DAD analysis, we determined that phenolic acids and flavonoids were the primary constituents of the CSEE extract. The results of the DPPH test indicated a potent scavenging capacity of the extract with an IC₅₀ of 302.78 ± 7.55 µg/mL, which was comparable to that of ascorbic acid with an IC₅₀ of 260.24 ± 6.45 µg/mL. Similarly, the β-carotene test demonstrated an IC₅₀ of 352.06 ± 12.16 µg/mL, signifying the extract's potential to inhibit oxidative damage. The ABTS assay revealed IC₅₀ values of 48.13 ± 3.66 TE µmol/mL, indicating a strong ability of CSEE to scavenge ABTS radicals, and the TAC assay demonstrated an IC₅₀ value of 165 ± 7.66 µg AAE/mg. The results suggest that the CSEE extract had potent antioxidant activity. Regarding its antimicrobial activity, the CSEE extract was effective against all five tested bacterial strains, indicating its broad-spectrum antibacterial properties. However, it only showed moderate activity against the two tested fungal strains, suggesting it may not be as effective against fungi. The CSEE exhibited a noteworthy dose-dependent inhibitory activity against all the tested tumor cell lines in vitro. The extract did not induce DNA damage at the concentrations of 6.25, 12.5, 25, and 50 µg/mL, as assessed by the comet assay. However, the 100 µg/mL concentration of CSEE resulted in a significant genotoxic effect compared to the negative control. A computational analysis was conducted to determine the physicochemical and pharmacokinetic characteristics of the constituent molecules present in the extract. The Prediction of Activity Spectra of Substances (PASS) test was employed to forecast the potential biological activities of these molecules. Additionally, the toxicity of the molecules was evaluated using the Protox II webserver.

Beneficial properties of Drimia numidica leaf methanolic extract against the cytogenotoxic effects of mitomycin C on human lymphocytes

This study investigated the phytochemical profile of Drimia numidica leaf methanolic extract, as well as its cyto-genotoxic and cyto/genoprotective potential against mitomycin C (MMC) mediated effects on healthy human lymphocytes. Photosynthetic pigments, trace elements, and secondary metabolites were estimated and/or identified in methanolic extract of mature leaves, and the latter was further used for assessing its in vitro biological effects on MMC-free and/or MMC-treated human lymphocytes (at low, non-toxic concentrations of 0.001 and 0.01% v/v). The results showed that D. numidica leaf methanolic extract, being rich in carotenoids, phenolics, flavonoids, organic acids and bufadienolides, could be protective against MMC mediated cyto/genotoxic potential in healthy human lymphocytes. Biomolecules possessing antioxidant and antitumor potential, such as beta-carotene and lutein among others, chlorogenic acid, caffeic acid and their derivatives, minerals such as Si, as well as apigenin- and luteolin-derived glycosides, either individual or in a mixture, could be beneficial rather than harmful, at least at the extract concentrations tested. Although further in vitro and in vivo studies are still needed for elucidating the beneficial (individual and/or additive/synergistic) role of those compounds, the results of the present study are quite promising, thus encouraging new challenges for the appropriate utilization of D. numidica leaf extract.

Protective Effects of Arbutus unedo L. Honey in the Alleviation of Irinotecan-Induced Cytogenetic Damage in Human Lymphocytes-An In Vitro Study

Strawberry tree (Arbutus unedo L.) honey (STH) has been used since ancient times as a folk medicine remedy, especially in certain Mediterranean countries. This honey, rich in phenolic content, is well recognized for its antioxidant, anti-inflammatory, and antimicrobial activities, and is used for the treatment of skin lesions as well as gastrointestinal and respiratory disorders. This study investigated whether STH alleviates genome damage in human peripheral blood lymphocytes produced by the cytotoxic drug irinotecan. The phenolic profile of STH was previously estimated by ultra-high-performance liquid chromatography coupled to a linear ion trap-Orbitrap hybrid mass spectrometer. The effects of STH were evaluated at three concentrations (1×, 5×, and 10×), based on the daily consumption of the honey by an adult person. After 2 h of in vitro exposure, standard lymphocyte cultures for the analysis of chromosome aberrations and the cytokinesis-block micronucleus cytome assay were established. Our results demonstrate that STH offered remarkable geno- and cytoprotection when administered with irinotecan. These findings are relevant for drawing preliminary conclusions regarding the in vitro safety of the tested honey. However, further studies are needed with the application of more complex experimental models.

Caffeic Acid and Diseases-Mechanisms of Action

Caffeic acid belongs to the polyphenol compounds we consume daily, often in the form of coffee. Even though it is less explored than caffeic acid phenethyl ester, it still has many positive effects on human health. Caffeic acid can affect cancer, diabetes, atherosclerosis, Alzheimer's disease, or bacterial and viral infections. This review focuses on the molecular mechanisms of how caffeic acid achieves its effects.

Dietary Phenolic Compounds as Anticancer Natural Drugs: Recent Update on Molecular Mechanisms and Clinical Trials

Given the stochastic complexity of cancer diseases, the development of chemotherapeutic drugs is almost limited by problems of selectivity and side effects. Furthermore, an increasing number of protective approaches have been recently considered as the main way to limit these pathologies. Natural bioactive compounds, and particularly dietary phenolic compounds, showed major protective and therapeutic effects against different types of human cancers. Indeed, phenolic substances have functional groups that allow them to exert several anti-cancer mechanisms, such as the induction of apoptosis, autophagy, cell cycle arrest at different stages, and the inhibition of telomerase. In addition, in vivo studies show that these phenolic compounds also have anti-angiogenic effects via the inhibition of invasion and angiogenesis. Moreover, clinical studies have already highlighted certain phenolic compounds producing clinical effects alone, or in combination with drugs used in chemotherapy. In the present work, we present a major advance in research concerning the mechanisms of action of the different phenolic compounds that are contained in food medicinal plants, as well as evidence from the clinical trials that focus on them.

Cytotoxic activity of strawberry tree (Arbutus unedo L.) honey, its extract, and homogentisic acid on CAL 27, HepG2, and Caco-2 cell lines

Strawberry tree (Arbutus unedo L.) honey (STH), also known as “bitter honey”, is a traditional medicine widely used in the Mediterranean area. Regardless of geographical origin, it usually has a very high content of phenolic compounds and strong antioxidant capacity. Yet, little is still known about the effects of STH, its phenolic extract (STHE), and its main bioactive compound – homogentisic acid (HGA) – at the cell level. The aim of this study was to estimate total phenolic content, DPPH radical scavenging activity, and ferric reducing antioxidant power of STH made in Croatia and investigate cytotoxic and pro-oxidative effects of STH, STHE and HGA on three human cell lines: tongue squamous cell carcinoma (CAL 27), hepatocellular carcinoma (HepG2), and epithelial colorectal adenocarcinoma cells (Caco-2) cells. These substances were tested at four concentrations (0.5–5× average human daily intake of STH) and over 30 min and 1 and 2 h. Croatian STH had a total phenolic content of 1.67 g gallic acid equivalents (GAE) per kg of honey, DPPH radical scavenging activity of 2.96 mmol Trolox equivalents (TE) per kg of honey, and ferric reducing antioxidant power (FRAP) of 13.5 mmol Fe²⁺ per kg of honey. Our results show no clear and consistent time- or concentration-dependent cytotoxicity in any of the cell lines. ROS levels in all the three cell types at almost all exposure times were not significantly higher than control. The most important observation is that the tested substances have low cytotoxicity and high biocompatibility, regardless of concentration, which is a good starting point for further research of their biological effects in other models.

Understanding the Prooxidant Action of Plant Polyphenols in the Cellular Microenvironment of Malignant Cells: Role of Copper and Therapeutic Implications

Plant derived polyphenolic compounds are considered critical components of human nutrition and have shown chemotherapeutic effects against a number of malignancies. Several studies have confirmed the ability of polyphenols to induce apoptosis and regression of tumours in animal models. However, the mechanism through which polyphenols modulate their malignant cell selective anticancer effects has not been clearly established. While it is believed that the antioxidant properties of these molecules may contribute to lowering the risk of cancer induction by causing oxidative damage to DNA, it could not be held responsible for chemotherapeutic properties and apoptosis induction. It is a well known fact that cellular copper increases within the malignant cell and in serum of patients harboring malignancies. This phenomenon is independent of the cellular origin of malignancies. Based on our own observations and those of others; over the last 30 years our laboratory has shown that cellular copper reacts with plant derived polyphenolic compounds, by a Fenton like reaction, which generates reactive oxygen species and leads to genomic DNA damage. This damage then causes an apoptosis like cell death of malignant cells, while sparing normal cells. This communication reviews our work in this area and lays the basis for understanding how plant derived polyphenols can behave as prooxidants (and not antioxidants) within the microenvironment of a malignancy (elevated copper levels) and gives rationale for their preferential cytotoxicity towards malignant cells.

Pro-Oxidant and Cytotoxic Effects of Tucum-Do-Cerrado (Bactris setosa Mart.) Extracts in Colorectal Adenocarcinoma Caco-2 Cells

Colorectal cancer is one of the most common types of cancer. Bioactive natural compounds can act in cancer chemoprevention as tumor growth inhibitors. Tucum-do-cerrado (Bactris setosa Mart.) is a Brazilian fruit that contains several phenolic compounds. This study investigated the effect of tucum aqueous extract in Caco-2 cells in comparison to primary human intestinal organoids and fibroblasts. Cells were exposed to 0.5 and 1 mg/ml of tucum aqueous extract for 24 h. ROS production, mRNA levels for SOD1 and SOD2, CAT, GPX1, NFE2L2, HIF1A and NOS2 were evaluated in Caco-2 cells exposed to tucum extract. Cell viability of Caco-2 cells was decreased upon tucum extract exposure. Mitochondrial ROS levels increased in Caco-2 cells exposed to tucum extract. The mRNA levels of SOD1, SOD2, CAT, GPX, NFE2L2 and HIF1A were downregulated in Caco-2 cells exposed to tucum extract, while NOS2 mRNA levels remained unchanged. Protein levels of SOD2, CAT and NRF2 remained unchanged in Caco-2 cells treated with tucum extract, indicating that catalase and SOD2 cellular functions may be unaffected by the tucum extract at 24 h, of exposure. Aqueous extract of tucum-do-cerrado may induce cellular toxicity in a cancer cell-specific manner, possibly through increased mitochondrial ROS production and gene expression regulation.

Caffeic acid protects human trophoblast HTR-8/SVneo cells from H2O2-induced oxidative stress and genotoxicity

Caffeic acid is highlighted as one of the major phenolic compounds present in foods with known antioxidant activity. This phenolic is among commonly consumed substances in everyday diet of pregnant women. However, there is not enough information on its effects during pregnancy, especially the most vulnerable early stage. Extravillous trophoblast cells are specific cells of the placenta that come in direct contact with maternal uterine tissue. Through this study we investigated the cytoprotective effects of caffeic acid on H₂O₂-induced oxidative damage in first trimester extravillous trophoblast cell line HTR-8/SVneo. Investigated concentrations (1-100 μM) of caffeic acid showed neither cytotoxic nor genotoxic effects on HTR-8/SVneo cells. The treatment with caffeic acid 100 μM significantly increased the percentage of cells in G2/M phase of the cell cycle, compared to non-treated cells. Pretreatment with caffeic acid (10 and 100 μM) attenuated oxidative DNA damage significantly, reduced cytotoxicity, protein and lipid peroxidation, and restored antioxidant capacity in trophoblast cells following H₂O₂ exposure. This beneficial outcome is probably mediated by the augmentation of GSH and effective ROS scavenging by caffeic acid. These promising results require further investigations to reveal the additional mechanisms/pathways and confirmation through studies in vivo.

Homogentisic acid, a main phenolic constituent of strawberry tree honey, protects human peripheral blood lymphocytes against irinotecan-induced cytogenetic damage in vitro

Homogentisic acid (HGA) is the most abundant phenolic compound in strawberry tree (Arbutus unedo L.) honey and an intermediate in the metabolism of phenylalanine and tyrosine. Since HGA exerts its dual nature (pro-oxidant and antioxidant), which depends on the concentration and cell type, the aim of study was to determine whether HGA possess cytoprotective effects and could counteract the cyto- and genotoxic effects of the antineoplastic drug irinotecan (IRI). Tested concentrations corresponded to HGA content in average daily dose of strawberry tree honey as well as five- and ten-fold higher concentrations. Cyto- and genoprotective effects were tested on human peripheral blood lymphocytes using chromosomal aberrations assay and cytokinesis-block micronucleus cytome assay. HGA, even at concentrations 10-fold higher than the one present in the daily amount of consumed strawberry tree honey, posed a non-significant cytotoxic threat to lymphocytes, had a negligible potential for causing cytogenetic damage in treated cells, and did not significantly impair their proliferation. Results of the chromosomal aberration assay and CBMN Cyt assay also showed that HGA efficiently counteracted the detrimental cytogenetic effects of IRI in vitro. The finding on cyto- and genoprotective effects of HGA merits further research in order to better explain the safety profile of this compound and to assess its potency for the development of novel nutraceutical products.

Mechanism of synergistic DNA damage induced by caffeic acid phenethyl ester (CAPE) and Cu(II): Competitive binding between CAPE and DNA with Cu(II)/Cu(I)

Caffeic acid phenethyl ester (CAPE) is an active polyphenol of propolis from honeybee hives, and exhibits antioxidant and interesting pharmacological activities. However, in this study, we found that in the presence of Cu(II), CAPE exhibited pro-oxidative rather than antioxidant effect: synergistic DNA damage was induced by the combination of CAPE and Cu(II) together as measured by strand breakage in plasmid DNA and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation, which is dependent on the molar ratio of CAPE:Cu(II). Production of Cu(I) and H₂O₂ from the redox reaction between CAPE and Cu(II), and subsequent OH formation was found to be responsible for the synergistic DNA damage. DNA sequencing investigations provided more direct evidence that CAPE/Cu(II) caused preferential cleavage at guanine, thymine and cytosine residues. Interestingly, we found there are competitive binding between CAPE and DNA with Cu(II)/Cu(I), which changed the redox activity of Cu(II)/Cu(I), via complementary applications of different analytical methods. The observed DNA damage was mainly attributed to the formation of DNA-Cu(II)/Cu(I) complexes, which is still redox active and initiated the redox reaction near the binding site between copper and DNA. Based on these data, we proposed that the synergistic DNA damage induced by CAPE/Cu(II) might be due to the competitive binding between CAPE and DNA with Cu, and site-specific production of OH near the binding site of copper with DNA. Our findings may have broad biological implications for future research on the pro-oxidative effects of phenolic compounds in the presence of transition metals.

Caffeic acid and chlorogenic acid cytotoxicity, genotoxicity and impact on global DNA methylation in human leukemic cell lines

Dietary phenolic compounds such as caffeic and chlorogenic acid exert an antiproliferative effect and modulate the gene-specific DNA methylation status in human breast tumor cells, but it remains unclear whether they interfere with global DNA methylation in human leukemia cells. We examined whether caffeic and chlorogenic acid (1-250 µM) exert antitumor action in human promyelocytic leukemia cells (HL-60) and human acute T-cell leukemia cells (Jurkat). Caffeic and chlorogenic acid did not reduce cell viability in the two cell lines, as assessed using the neutral red uptake and MTT assays. These phenolic acids (1-100 μM) neither induced DNA damage (comet assay) nor increased the micronuclei frequency (micronucleus assay) in HL-60 and Jurkat cells, indicating that they were not genotoxic or mutagenic. Analysis of global DNA methylation levels using a 5-mC DNA ELISA kit revealed that chlorogenic acid at a non-cytotoxic concentration (100 μM) induced global DNA hypomethylation in Jurkat cells, but not in HL-60 cells, suggesting that it exerts a cell-specific effect. Caffeic acid did not change global DNA methylation. As other phenolic compounds, chlorogenic acid probably modulates DNA methylation by targeting DNA methyltransferases. The hypomethylating action of chlorogenic acid can be beneficial against hematological malignances whose pathogenic processes involve impairment of DNA methylation.

Genotoxic and cytotoxic properties of two medical plants (Teucrium arduini L.and Teucrium flavum L.) in relation to their polyphenolic contents

A large number of species belonging to the genus Teucrium are used in pharmacy and traditional medicine for the treatment of different diseases. This study aimed to evaluate the polyphenolic composition as well as genotoxic and cytotoxic effects of methanolic extracts from T. arduini and T. flavum, two native species found in Montenegro. We determined the total phenolic and flavonoid contents of these plants using spectrophotometric methods; the qualitative content of polyphenolic compounds was investigated by high-performance liquid chromatography (HPLC). Genotoxicity in cultured human lymphocytes was measured in the cytokinesis-block micronucleus assay (CBMN) and comet assay in the range between 125 and 1000 μg/mL. Cytotoxicity was assessed by the MTT viability assay in normal human MRC-5 fibroblasts and MDA-MB-231 breast carcinoma cells. The content of total phenolics and flavonoids in T. arduini extract was higher than in T. flavum (200.35 mg GA/g vs. 171.08 mg GA/g; 96.32 mg RU/g vs. 78.14 mg RU/g). The polyphenolic composition of both extracts was qualitatively similar and eight phenol compounds were identified. The most commonly present phenol was caffeic acid and among four flavonoids, the most common was quercetin. Both plant extracts were genotoxic in both the CBMN and comet assays at concentrations of 250, 500 and 1000 μg/mL. After 72 h of exposure, the extracts of T. arduini and T. flavum were found to induce cytotoxicity in MRC-5 fibroblasts but not in MDA-MB-231 breast cancer cells. The results suggest that the constituents of both plant species are genotoxic and cytotoxic, therefore these extracts warrant additional evaluation to be safely applied in humans.

Antigenotoxic, Anti-photogenotoxic, and Antioxidant Properties of Polyscias filicifolia Shoots Cultivated In Vitro

Traditional medicinal plants are an important source of active compounds with potential antimutagenic activity. Polyscias filicifolia Bailey (Araliaceae) is a South Asian traditional herb used as an adaptogenic and cardiac drug. Extracts of P. filicifolia contain a wide range of biologically active compounds like phenolic acids and triterpenoid saponins. In the present study. antigenotoxic potential of three naturally occurring phenolic acids and extracts of P. filicifolia growing in vitro with the addition of elicitors was evaluated against direct (4-nitroquinoline-N-oxide (4NQO) and mitomycin C (MMC)) and indirect mutagens (2-aminoanthracene (2AA)). The evaluation was made using a bacterial umu-test. Moreover, the ability to prevent photogenotoxicity induced by chlorpromazine (CPZ) under UVA irradiation was measured. The phytochemical profiling of examined extracts revealed the presence of numerous compounds with the prevelance of chlorogenic, caffeic, and ferulic acid derivatives; however, saponin fractions were also determined. The antioxidant potential of extracts strictly correlated with their composition. The tested extracts exhibited high antigenotoxic activity if the assay was performed with 2AA and metabolic activation. Moreover, the extracts slightly decreased the MMC-induced genotoxicity. However, an increase of the genotoxic effect was observed in the assay performed with 4NQO. In addition, photo-antigenotoxic activity was observed. In our study, phenolic acids exhibited lower activity than the extracts.

In Vitro Pro-Glycative Effects of Resveratrol and Caffeic Acid

Resveratrol and caffeic acid belong to plant polyphenols and are known for their antioxidant effects. The aim of our research was to study their impact on Maillard reaction. This one occurs when the reducing saccharides react with amino groups of biomolecules including proteins, alter their protein conformation and transform to the variety of advanced glycation end products (AGEs). AGEs exhibit browning and generate fluorescence. There exist expectations that this oxidative protein glycosylation could be prevented by antioxidants. In this study, we incubated bovine serum albumin (BSA) with glucose for 7 days at 37°C and measured characteristic fluorescence and UV absorbance of the formed AGEs. Surprisingly, resveratrol and caffeic acid enhanced transformation of BSA to glycation products, which was confirmed either when cupric Cu(II) or ferric Fe(III) ions in nanomolar concentration were added to the system as pro-oxidant agent.

Mitochondriotropic action and DNA protection: Interactions between phenolic acids and enzymes

The protective action of caffeic (CA) and syringic (SA) acids on the genotoxicity exercised by snake venoms was investigated in this study. Molecular interactions between phenolic acids and the enzyme succinate dehydrogenase were also explored. In the electrophoresis assay, SA did not inhibit the genotoxicity induced by the venom. However, CA partially inhibited DNA degradation. In the comet assay, SA and CA exerted an inhibitory effect on the venom-induced fragmentation. Succinate dehydrogenase presented, in computational analyzes, favorable energies to the molecular bond to both the malonic acid and the phenolic compounds evaluated. In the enzymatic activity assays, SA inhibited succinate dehydrogenase and interfered in the interaction of malonic acid. Meanwhile, CA potentiated the inhibition exerted by the malonic acid. The results suggest transient interactions between toxins present in venoms and phenolic acids, mainly by hydrogen interactions, which corroborate with the data from previous works.

Lamium Plants-A Comprehensive Review on Health Benefits and Biological Activities

This work is an updated snapshot of Lamium plants and their biological activities. The main features of the plant are described and the components of its essential oils are summarized. The traditional medicinal uses of Lamium plants has been reported. The presence of these chemicals i.e., hydroxycinnamic acids, iridoids, secoiridoids, flavonoids, anthocyanins, phenylpropanoids, phytoecdysteroids, benzoxazinoids, betaine can provide biological activities. After the discussion of antioxidant properties documented for Lamium plants, the biological activities, studied using in vitro models, antimicrobial, antiviral, anti-inflammatory, anti-nociceptive activity, and pain therapy and cytotoxicity and cytoprotective activity are here described and discussed. Finally, targeted examples of in vivo studies are reported.

An in silico investigation on the inhibitory potential of the constituents of Pomegranate juice on antioxidant defense mechanism: Relevance to neurodegenerative diseases

Elevation in the levels of reactive oxygen and nitrogen species (RONS), and downregulation of cellular antixoidants, have ubiquitously been reported from studies in animal models of neurodegenerative diseases, including Parkinson’s disease (PD) and Alzheimer’s disease (AD). Thus, plant-derived compounds are widely being investigated for their beneficial effects in these models. However, while studies have reported antioxidant potentials of several phytochemicals, a large number of studies have demonstrated different phytochemicals to be rather pro-oxidant and exaggerate oxidative stress (OS). One such study aimed to investigate possible ameliorative effect of Pomegranate juice (PJ) in rat model of toxin-induced parkinsonism revealed that PJ exacerbates OS, inflammation and promotes neurodegeneration. Thus, it remains to be investigated whether different constituents and metabolites of PJ are pro-oxidant or anti-oxidant. Using computational modeling, we investigated possible inhibitory potential of different constituents of PJ and their metabolites viz. delphinidin-3-glucoside, dimethylellagic acid-glucuronide, ellagic acid, ellagitannin, gallic acid, gallotannin 23, pelargonidin, punicalagin, urolithin A, urolithin A-glucuronide and urolithin B, on anti-oxidant defense system of the brain. The results indicate that the constituents of PJ have the potential to inhibit five key enzymes of the neuronal antioxidant defense system, viz. catalase, superoxide dismutase, glutathione peroxidase 4, glutathione reductase and glutathione-S-transferase. Thus, it is surmised that the constituents of PJ may contribute to OS and neurodegeneration by way of affecting antioxidant defense mechanism. This may particularly be more pronounced in neurodegenerative diseases, since neurons are known to be more vulnerable to OS. Thus, the present findings caution the use of PJ in patients prone to OS, especially those suffering from neurodegenerative diseases, and warrant further experimental studies to unveil the effects of individual components and metabolites of PJ on antioxidant defense system of brain.

Phytochemical composition, antioxidant and antiproliferative activities and effects on nuclear DNA of ethanolic extract from an Italian mycelial isolate of Ganoderma lucidum

ETHNOPHARMACOLOGICAL RELEVANCE

Ganoderma lucidum (Curtis) P. Karst. (also known as Linghzhi and Reishi) is the most appreciated and revered medicinal mushroom across many Asian countries, but its properties have also attracted interest in Western countries. Indeed, in the West, it is now commercially available as a dietary supplement in preparations mainly made from spores, fruiting bodies and mycelia. It is employed in both nutraceutical and pharmacological formulations either for its immuno-modulating anti-inflammatory properties or as an effective adjuvant therapy in the treatment of several chronic diseases as well as in cancer treatment.

AIM OF THE STUDY

The aim of this investigation was to show the phytochemical composition and antioxidant and antiproliferative activities of an ethanolic extract from an Italian mycelial isolate of Ganoderma lucidum and to assess its effects on nuclear DNA.

MATERIALS AND METHODS

LC/ESI-MS and tandem mass spectrometry MSMS were used to obtain structural identification of ethanolic G. lucidum extract constituents. Antioxidant activities were determined by the DPPH method, chelating effect on Fe²⁺ and lipoxygenase inhibition while cytotoxic activities using the MTT assay. Effects on nuclear DNA were evaluated using the DNA nicking assay in a cell-free system and the fast halo assay performed on oxidatively injured human U937 cells; apoptosis induction was investigated using the non-denaturing fast halo assay and DNA laddering detection.

RESULTS

This extract was rich in several bioactive compounds, mainly phenolic and triterpenic acids. It showed antioxidant activity and protective effects in oxidatively injured DNA in cell-free analyses and antiproliferative, genotoxic, and proapoptotic effects in the cell model.

CONCLUSIONS

Italian G. lucidum mycelium isolate appears to be a source of various natural compounds that may have applications as chemopreventive agents or functional foods.

Cells Deficient in the Fanconi Anemia Protein FANCD2 are Hypersensitive to the Cytotoxicity and DNA Damage Induced by Coffee and Caffeic Acid

Epidemiological studies have found a positive association between coffee consumption and a lower risk of cardiovascular disorders, some cancers, diabetes, Parkinson and Alzheimer disease. Coffee consumption, however, has also been linked to an increased risk of developing some types of cancer, including bladder cancer in adults and leukemia in children of mothers who drink coffee during pregnancy. Since cancer is driven by the accumulation of DNA alterations, the ability of the coffee constituent caffeic acid to induce DNA damage in cells may play a role in the carcinogenic potential of this beverage. This carcinogenic potential may be exacerbated in cells with DNA repair defects. People with the genetic disease Fanconi Anemia have DNA repair deficiencies and are predisposed to several cancers, particularly acute myeloid leukemia. Defects in the DNA repair protein Fanconi Anemia D2 (FANCD2) also play an important role in the development of a variety of cancers (e.g., bladder cancer) in people without this genetic disease. This communication shows that cells deficient in FANCD2 are hypersensitive to the cytotoxicity (clonogenic assay) and DNA damage (γ-H2AX and 53BP1 focus assay) induced by caffeic acid and by a commercial lyophilized coffee extract. These data suggest that people with Fanconi Anemia, or healthy people who develop sporadic mutations in FANCD2, may be hypersensitive to the carcinogenic activity of coffee.

Dietary phytochemicals alter epigenetic events and signaling pathways for inhibition of metastasis cascade: phytoblockers of metastasis cascade

Cancer metastasis is a multistep process in which a cancer cell spreads from the site of the primary lesion, passes through the circulatory system, and establishes a secondary tumor at a new nonadjacent organ or part. Inhibition of cancer progression by dietary phytochemicals (DPs) offers significant promise for reducing the incidence and mortality of cancer. Consumption of DPs in the diet has been linked to a decrease in the rate of metastatic cancer in a number of preclinical animal models and human epidemiological studies. DPs have been reported to modulate the numerous biological events including epigenetic events (noncoding micro-RNAs, histone modification, and DNA methylation) and multiple signaling transduction pathways (Wnt/β-catenin, Notch, Sonic hedgehog, COX-2, EGFR, MAPK-ERK, JAK-STAT, Akt/PI3K/mTOR, NF-κB, AP-1, etc.), which can play a key role in regulation of metastasis cascade. Extensive studies have also been performed to determine the molecular mechanisms underlying antimetastatic activity of DPs, with results indicating that these DPs have significant inhibitory activity at nearly every step of the metastatic cascade. DPs have anticancer effects by inducing apoptosis and by inhibiting cell growth, migration, invasion, and angiogenesis. Growing evidence has also shown that these natural agents potentiate the efficacy of chemotherapy and radiotherapy through the regulation of multiple signaling pathways. In this review, we discuss the variety of molecular mechanisms by which DPs regulate metastatic cascade and highlight the potentials of these DPs as promising therapeutic inhibitors of cancer.

Change in chemical constituents and free radical-scavenging activity during Pear (Pyrus pyrifolia) cultivar fruit development

Changes in chemical constituent contents and DPPH radical-scavenging activity in fruits of pear (Pyrus pyrifolia) cultivars during the development were investigated. The fruits of seven cultivars (cv. Niitaka, Chuhwangbae, Wonhwang, Hwangkeumbae, Hwasan, Manpungbae, and Imamuraaki) were collected at 15-day intervals after day 20 of florescence. Vitamins (ascorbic acid and α-tocopherol), arbutin, chlorogenic acid, malaxinic acid, total caffeic acid, total flavonoids, and total phenolics were the highest in immature pear fruit on day 20 after florescence among samples at different growth stages. All of these compounds decreased gradually in the fruit during the development. Immature pear fruit on day 35 or 50 after florescence exhibited higher free radical-scavenging activity than that at other times, although activities were slightly different among cultivars. The chemical constituent contents and free radical-scavenging activity were largely different among immature fruits of the pear cultivars, but small differences were observed when they matured.

Preparation of MIP-based QCM nanosensor for detection of caffeic acid

In the present work, a new caffeic acid imprinted quartz crystal microbalance (QCM) nanosensor has been designed for selective assignation of caffeic acid in plant materials. Methacrylamidoantipyrine-iron(III) [MAAP-Fe(III)] as metal-chelating monomer has been used to prepare selective molecular imprinted polymer (MIP). MIP film for detection of caffeic acid has been developed on QCM electrode and selectivity experiments and analytical performance of caffeic acid imprinted QCM nanosensor has been studied. The caffeic acid imprinted QCM nanosensor has been characterized by AFM. After the characterization studies, imprinted and non-imprinted nanosensors was connected to QCM system for studies of connection of the target molecule, selectivity and the detection of amount of target molecule in real samples. The detection limit was found to be 7.8 nM. The value of Langmuir constant (b) (4.06 × 10(6)) that was acquired using Langmuir graph demonstrated that the affinity of binding sites was strong. Also, selectivity of prepared caffeic acid imprinted nanosensor was found as being high compared to chlorogenic acid. Finally, the caffeic acid levels in plant materials was determined by the prepared QCM nanosensor.

Pomegranate juice exacerbates oxidative stress and nigrostriatal degeneration in Parkinson's disease

Numerous factors contribute to the death of substantia nigra (SN) dopamine (DA) neurons in Parkinson's disease (PD). Compelling evidence implicates mitochondrial deficiency, oxidative stress, and inflammation as important pathogenic factors in PD. Chronic exposure of rats to rotenone causes a PD-like syndrome, in part by causing oxidative damage and inflammation in substantia nigra. Pomegranate juice (PJ) has the greatest composite antioxidant potency index among beverages, and it has been demonstrated to have protective effects in a transgenic model of Alzheimer's disease. The present study was designed to examine the potential neuroprotective effects of PJ in the rotenone model of PD. Oral administration of PJ did not mitigate or prevent experimental PD but instead increased nigrostriatal terminal depletion, DA neuron loss, the inflammatory response, and caspase activation, thereby heightening neurodegeneration. The mechanisms underlying this effect are uncertain, but the finding that PJ per se enhanced nitrotyrosine, inducible nitric oxide synthase, and activated caspase-3 expression in nigral DA neurons is consistent with its potential pro-oxidant activity.

Plant polyphenol induced cell death in human cancer cells involves mobilization of intracellular copper ions and reactive oxygen species generation: a mechanism for cancer chemopreventive action

SCOPE

Anticancer polyphenolic nutraceuticals from fruits, vegetables, and spices are generally recognized as antioxidants, but can be prooxidants in the presence of copper ions. We earlier proposed a mechanism for such activity of polyphenols and now we provide data in multiple cancer cell lines in support of our hypothesis.

METHODS AND RESULTS

Through multiple assays, we show that polyphenols luteolin, apigenin, epigallocatechin-3-gallate, and resveratrol are able to inhibit cell proliferation and induce apoptosis in different cancer cell lines. Such cell death is prevented to a significant extent by cuprous chelator neocuproine and reactive oxygen species scavengers. We also show that normal breast epithelial cells, cultured in a medium supplemented with copper, become sensitized to polyphenol-induced growth inhibition.

CONCLUSION

Since the concentration of copper is significantly elevated in cancer cells, our results strengthen the idea that an important anticancer mechanism of plant polyphenols is mediated through intracellular copper mobilization and reactive oxygen species generation leading to cancer cell death. Moreover, this prooxidant chemopreventive mechanism appears to be a mechanism common to several polyphenols with diverse chemical structures and explains the preferential cytotoxicity of these compounds toward cancer cells.

Redox cycling of endogenous copper by thymoquinone leads to ROS-mediated DNA breakage and consequent cell death: putative anticancer mechanism of antioxidants

Plant-derived dietary antioxidants have attracted considerable interest in recent past for their chemopreventive and cancer therapeutic abilities in animal models. Thymoquinone (TQ) is the major bioactive constituent of volatile oil of Nigella sativa and has been shown to exert various pharmacological properties, such as anti-inflammatory, cardiovascular, analgesic, anti-neoplastic, anticancer and chemopreventive. Although several mechanisms have been suggested for the chemopreventive and anticancer activity of TQ, a clear mechanism of action of TQ has not been elucidated. TQ is a known antioxidant at lower concentrations and most of the studies elucidating the mechanism have centered on the antioxidant property. However, recent publications have shown that TQ may act as a prooxidant at higher concentrations. It is well known that plant-derived antioxidants can switch to prooxidants even at low concentrations in the presence of transition metal ions such as copper. It is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies. Copper is an important metal ion present in the chromatin and is closely associated with DNA bases, particularly guanine. Using human peripheral lymphocytes and comet assay, we first show that TQ is able to cause oxidative cellular DNA breakage. Such a DNA breakage can be inhibited by copper-chelating agents, neocuproine and bathocuproine, and scavengers of reactive oxygen species. Further, it is seen that TQ targets cellular copper in prostate cancer cell lines leading to a prooxidant cell death. We believe that such a prooxidant cytotoxic mechanism better explains the anticancer activity of plant-derived antioxidants.

Caffeic acid treatment alters the extracellular adenine nucleotide hydrolysis in platelets and lymphocytes of adult rats

This study evaluated the effects of caffeic acid on ectonucleotidase activities such as NTPDase (nucleoside triphosphate diphosphohydrolase), Ecto-NPP (nucleotide pyrophosphatase/phosphodiesterase), 5'-nucleotidase and adenosine deaminase (ADA) in platelets and lymphocytes of rats, as well as in the profile of platelet aggregation. Animals were divided into five groups: I (control); II (oil); III (caffeic acid 10 mg/kg); IV (caffeic acid 50 mg/kg); and V (caffeic acid 100 mg/kg). Animals were treated with caffeic acid diluted in oil for 30 days. In platelets, caffeic acid decreased the ATP hydrolysis and increased ADP hydrolysis in groups III, IV and V when compared to control (P<0.05). The 5'-nucleotidase activity was decreased, while E-NPP and ADA activities were increased in platelets of rats of groups III, IV and V (P<0.05). Caffeic acid reduced significantly the platelet aggregation in the animals of groups III, IV and V in relation to group I (P<0.05). In lymphocytes, the NTPDase and ADA activities were increased in all groups treated with caffeic acid when compared to control (P<0.05). These findings demonstrated that the enzymes were altered in tissues by caffeic acid and this compound decreased the platelet aggregation suggesting that caffeic acid should be considered a potentially therapeutic agent in disorders related to the purinergic system.

Structure-anti-leukemic activity relationship study of ortho-dihydroxycoumarins in U-937 cells: key role of the δ-lactone ring in determining differentiation-inducing potency and selective pro-apoptotic action

Previous studies indicated the need of at least one phenolic hydroxyl group in the coumarin core for induction of cytotoxicity in different cell lines. Herein, we present an exhaustive structure-activity relationship study including ortho-dihydroxycoumarins (o-DHC) derivatives, cinnamic acid derivatives (as open-chain coumarin analogues) and 1,2-pyrones (representative of the δ-lactone ring of the coumarin core), carried out to further identify the structural features of o-DHC required to induce leukemic cell differentiation and apoptosis in U-937 cells. Our results show for the first time that the δ-lactone ring positively influences the aforementioned biological effects, by conferring greater potency to compounds with an intact coumarin nucleus. Most tellingly, we reveal herein the crucial role of this molecular portion in determining the selective toxicity that o-DHC show for leukemic cells over normal blood cells. From a pharmacological perspective, our findings point out that o-DHC may be useful prototypes for the development of novel chemotherapeutic agents.

The coffee constituent chlorogenic acid induces cellular DNA damage and formation of topoisomerase I- and II-DNA complexes in cells

Chlorogenic acid (CGA) is a plant polyphenol with known antioxidant properties. Although some studies suggest that CGA has anticancer properties, others indicate that this dietary constituent may cause DNA damage and induce carcinogenic effects. Because CGA is widely consumed in the form of coffee, it is important to further evaluate the putative DNA-damaging activity of CGA. Here we have employed two standard techniques commonly used for DNA damage detection (the comet assay and the γ- H2AX focus assay) and observed that CGA (0.5-5 mM) induces DNA damage in normal and cancer cells. We report for the first time that CGA induces high levels of topoisomerase I- and topoisomerase II-DNA complexes in cells (TARDIS assay). Catalase pretreatment abolished the formation of these topoisomerase-DNA complexes and reduced the cytotoxic activity of CGA, therefore indicating that hydrogen peroxide plays an important role in these activities. Lung cancer cells (A549) were more sensitive than normal lung fibroblasts (MRC5) to the cytotoxic activity of CGA, supporting previous findings that CGA may induce selective killing of cancer cells. Taking into consideration our results and the pharmacokinetic profile of CGA, the possible cancer preventive, carcinogenic and therapeutic potential of this dietary agent are discussed.

In vitro cytogenetic and genotoxic effects of curcumin on human peripheral blood lymphocytes

Curcumin has shown a wide range of properties such as anti-inflammatory and anti-carcinogenic properties. Many of these effects, mainly the anti-carcinogenic effect, could be linked to its anti-oxidant effects. Nevertheless, some studies suggest that this natural compound possesses both pro- and anti-oxidative effects and that curcumin could be a genotoxic agent for some cell lines. We evaluated the genetic damage induced by curcumin to human lymphocytes exposed to increasing concentrations (0-50 μg/ml) of curcumin. Biomarkers such as chromosome aberrations (CAs) and sister chromatid exchange (SCE) were analyzed. In addition to the cytogenetic analysis, the effect of curcumin in the cell proliferation kinetics (CPK) by the proliferation index (PI) was also analyzed. The results indicated that high concentrations of curcumin induced CAs, mainly acentric fragments. SCEs rate was not statistically different from the control group in any curcumin treated cell group. The PI of cells treated with 2 and 5 μg/ml of curcumin were statistically significant from the control group and finally, the MI showed a tendency to increase in all the concentrations of curcumin tested. In conclusion, it can be assumed that the higher concentrations of curcumin evaluated have a cyto and genotoxic effect, in vitro, for human peripheral lymphocytes.

Apogossypolone, derivative of gossypol, mobilizes endogenous copper in human peripheral lymphocytes leading to oxidative DNA breakage

Gossypol is a polyphenolic aldehyde that is produced in the cotton plant. Since long it has been reported to possess antiproliferative activity against a variety of cancer cell lines as well as tumor regression in animal models. However, the toxicity of gossypol does not permit it to be an effective antitumor agent. One of the derivatives of gossypol to show promising results is apogossypolone. For example, it has been shown to specifically target tumor growth in hepatocellular carcinoma xenograft in nude mice without causing any damage to normal tissue. Using human peripheral lymphocytes, in this paper we show that both gossypol and its semi-synthetic derivative apogossypolone cause oxidative DNA breakage in these cells through the mobilization of endogenous copper ions. Such cellular DNA breakage is inhibited by copper specific chelator but nor by iron or zinc chelating agents. Similar results are obtained with isolated nuclei indicating that chromatin bound copper is mobilized in this reaction. Further, apogossypolone showed enhanced DNA breakage and increased oxidative stress in whole lymphocytes as compared with gossypol indicating that this is possibly the result of greater permeability of apogossypolone. It is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies. Therefore, cancer cells may be subject to greater electron transfer between copper ions and gossypol/apogossypolone to generate reactive oxygen species responsible for DNA cleavage. This may account for the preferential cytotoxicity of apogossypolone towards tumor cells.

Resveratrol-induced apoptosis is enhanced in low pH environments associated with cancer

Many critical factors such as hypoxia, nutrient deficiency, activation of glycolytic pathway/Warburg effect contribute to the observed low pH in tumors compared to normal tissue. Studies suggest that such tumor specific acidic environment can be exploited for the development of therapeutic strategies against cancer. Independent observations show reduction in pH of mammalian cells undergoing internucleosomal DNA fragmentation and apoptosis. As such, our group has extensively demonstrated that anticancer mechanisms of different plant polyphenols involve mobilization of endogenous copper and consequent internucleosomal DNA breakage. Copper is redox active metal, an essential component of chromatin and is sensitive to subtle pH changes in its microenvironment. Here we explored whether, acidic pH promotes growth inhibition, apoptosis, and DNA damaging capacity of chemopreventive agent resveratrol. Our results reveal that growth inhibition and internucleosomal DNA fragmentation induced apoptosis in Capan-2 and Panc-28 pancreatic cancer cell lines (and not in normal HPDE cells) by resveratrol is enhanced at lower pH. Using comet assay, we further demonstrate that DNA breakage by resveratrol is enhanced with acidification. Membrane permeable copper specific chelator neocuproine (and not iron chelator orthophenanthroline) abrogated growth inhibition and apoptosis by resveratrol. Western blot results show enhanced activation of DNA laddering marker H2.aX by resveratrol at acidic pH that was reversed by neocuproine and not by orthophenanthroline. Our findings provide irrevocable proof that low pH environment can be turned into tumor weakness and assist in eradication of cancer cells by resveratrol.

DNA breakage induced by piceatannol and copper(II): Mechanism and anticancer properties

Piceatannol (3,3',4,5'-tetrahydroxy-trans-stilbene; Pice), found in a variety of plant sources including grapes, red wine, peanuts and rhubarb, is known as a metabolite and analog of Resveratrol (3,5,4'-trihydroxy-trans-stilbene; Res) and has higher bioactivity than Res. To explore the mechanism of DNA damage induced by Pice in the presence of copper (Cu)(II), gel electrophoresis, UV-visible spectroscopy, fluorescence spectroscopy and Fourier transform infrared spectroscopy were used. The results of gel electrophoresis demonstrated that the hydroxyl radical played a critical role in DNA cleavage. Spectroscopy confirmed that the mechanism of DNA cleavage induced by Pice-Cu(II) involves the Haber Weiss and Fenton reactions. Pice chelates with Cu(II) as a bidentate ligand, and the Pice-Cu(II) complex undergoes intramolecular electron transfer to form the semiquinone radical anion and Cu(I), which may be reoxidated by O(2) to form Cu(II) with hydroxyl radical generation. In brief, the formation of the hydroxyl radical and the Cu(II)/Cu(I) redox cycle play a key role in inducing DNA damage. In this process, Pice demonstrated pro-oxidant properties. Oxidative product(s) of Pice, semiquinone, was formed and Cu(I) was reoxidized to Cu(II). The redox cycling of copper generated reactive oxygen species, which induced DNA cleavage, the hallmark of cell apoptosis. The mechanism of DNA breakage induced by Pice-Cu(II) may be a significant pathway through which cancer cells are killed.

Verbascoside is not genotoxic in the ST and HB crosses of the Drosophila wing spot test, and its constituent, caffeic acid, decreases the spontaneous mutation rate in the ST cross

Verbascoside (VB) is a phenylpropanoid isolated from Buddleja species, some of which originate in Mexico, and was first described in the sixteenth century in the codices of Mexican traditional medicine. VB is present in alcohol extracts and is widely used in the north of Mexico as a sunscreen. VB absorbs UV-A and UV-B radiation and has high antioxidant and anti-inflammatory capacities. VB and its constituent caffeic acid (CA) were screened to determine their genotoxic activity using the Drosophila wing spot test. Third instar larvae (72±4 h) of the standard (ST) and high bioactivation (HB) crosses, with regulated and high levels of cytochrome P450s (Cyp450s), respectively, were exposed to VB or CA (0, 27, 57, 81, 135, and 173 mM). VB was not genotoxic at any of the concentrations tested in both crosses. The amount of VB residue as determined by HPLC in the adult flies that were fed with VB indicated a low metabolism of this compound, which explains the absence of genotoxicity. CA decreased the spontaneous frequencies of small and total spots and showed putative toxicity in the ST cross.

Natural polyphenols may ameliorate damage induced by copper overload

The effect of the simultaneous exposure to transition metals and natural antioxidants frequently present in food is a question that needs further investigation. We aimed to explore the possible use of the natural polyphenols caffeic acid (CA), resveratrol (RES) and curcumin (CUR) to prevent damages induced by copper-overload on cellular molecules in HepG2 and A-549 human cells in culture. Exposure to 100μM/24h copper (Cu) caused extensive pro-oxidative damage evidenced by increased TBARS, protein carbonyls and nitrite productions in both cell types. Damage was aggravated by simultaneous incubation with 100μM of CA or RES, and it was also reflected in a decrease on cellular viability explored by trypan blue dye exclusion test and LDH leakage. Co-incubation with CUR produced opposite effects demonstrating a protective action which restored the level of biomarkers and cellular viability almost to control values. Thus, while CA and RES might aggravate the oxidative/nitrative damage of Cu, CUR should be considered as a putative protective agent. These results could stimulate further research on the possible use of natural polyphenols as neutralizing substances against the transition metal over-exposure in specific populations such as professional agrochemical sprayers and women using Cu-intrauterine devices.

Research strategies in the study of the pro-oxidant nature of polyphenol nutraceuticals

Polyphenols of phytochemicals are thought to exhibit chemopreventive effects against cancer. These plant-derived antioxidant polyphenols have a dual nature, also acting as pro-oxidants, generating reactive oxygen species (ROS), and causing oxidative stress. When studying the overall cytotoxicity of polyphenols, research strategies need to distinguish the cytotoxic component derived from the polyphenol per se from that derived from the generated ROS. Such strategies include (a) identifying hallmarks of oxidative damage, such as depletion of intracellular glutathione and lipid peroxidation, (b) classical manipulations, such as polyphenol exposures in the absence and presence of antioxidant enzymes (i.e., catalase and superoxide dismutase) and of antioxidants (e.g., glutathione and N-acetylcysteine) and cotreatments with glutathione depleters, and (c) more recent manipulations, such as divalent cobalt and pyruvate to scavenge ROS. Attention also must be directed to the influence of iron and copper ions and to the level of polyphenols, which mediate oxidative stress.

DNA damage induced by shikonin in the presence of Cu(II) ions: potential mechanism of its activity to apoptotic cell death

Shikonin (β-alkannin), a naphthazarin derivative, has shown a variety of abilities such as anti-inflammatory, antitumoral, cytotoxic, and antimicrobial activities. In the presence of Cu(II), shikonin caused breakage of supercoiled plasmid pBR322 DNA. Other metal ions tested [Mg(II), Ca(II), and Ni(II)] were ineffective and only Fe(II) has the same ability in the DNA breakage reaction. The involvement of active oxygen in the reaction was established by the inhibition of DNA breakage by superoxide dismutase, catalase, thiourea, sodium azide, potassium iodide, and sodium benzoate. Cu(I) was shown to be an essential intermediate using the Cu(I)-specific sequestering reagent neocuproine. Shikonin induced HeLa cell apoptosis involved in the mechanism of increasing intracellular reactive oxygen species (ROS). It was suggested that shikonin generated ROS as a pro-oxidant in the presence of Cu(II), and ROS resulted in DNA damage and apoptotic cell death in cells.

Inhibitory effect of caffeic acid on cancer cell proliferation by oxidative mechanism in human HT-1080 fibrosarcoma cell line

Caffeic acid (3,4-dihydroxy cinnamic acid) (CA) is naturally found in fruits, vegetables, olive oil, and coffee. This study was undertaken to evaluate the anticancer effect of caffeic acid on HT-1080 human fibrosarcoma cell line. The antiproliferative effect of caffeic acid was determined by MTT assay, and the oxidative stress was determined by lipid peroxidation, changes in the enzymatic, and non-enzymatic antioxidant status. To understand the mode of antiproliferative effect of CA, the authors observed intracellular ROS levels by DCFH-DA method, mitochondrial membrane potential alterations by Rh-123 staining, oxidative DNA damage by comet assay, and apoptotic morphological changes by AO/EtBr-staining method. The results show that caffeic acid enhances lipid peroxidative markers such as TBARS, CD, and LHP in HT-1080 cell line. Caffeic acid enhances the ROS levels, which is evidenced by the increased DCF fluorescence. Further, caffeic acid treatment altered the mitochondrial membrane potential in HT-1080 cells. Similarly, the authors observed increased oxidative DNA damage (% Tail DNA, % Tail length, Tail moment, and olive tail moment), and apoptotic morphological changes in caffeic acid-treated groups. These data suggest that caffeic acid exhibits potent anticancer effect in HT-1080 cell line, and that it may be used as an anticancer agent.

A review of the pharmacological effects of Arctium lappa (burdock)

Arctium lappa, commonly known as burdock, is being promoted/recommended as a healthy and nutritive food in Chinese societies. Burdock has been used therapeutically in Europe, North America and Asia for hundreds of years. The roots, seeds and leaves of burdock have been investigated in view of its popular uses in traditional Chinese medicine (TCM). In this review, the reported therapeutic effects of the active compounds present in the different botanical parts of burdock are summarized. In the root, the active ingredients have been found to "detoxify" blood in terms of TCM and promote blood circulation to the skin surface, improving the skin quality/texture and curing skin diseases like eczema. Antioxidants and antidiabetic compounds have also been found in the root. In the seeds, some active compounds possess anti-inflammatory effects and potent inhibitory effects on the growth of tumors such as pancreatic carcinoma. In the leaf extract, the active compounds isolated can inhibit the growth of micro-organisms in the oral cavity. The medicinal uses of burdock in treating chronic diseases such as cancers, diabetes and AIDS have been reported. However, it is also essential to be aware of the side effects of burdock including contact dermatitis and other allergic/inflammatory responses that might be evoked by burdock.

The proglycation effect of caffeic acid leads to the elevation of oxidative stress and inflammation in monocytes, macrophages and vascular endothelial cells

In this study, the effects of phenolic acids [caffeic acid (CA), ferulic acid, m-coumaric acid, and chlorogenic acid] on methylglyoxal (MG)-induced protein glycation were investigated in vitro. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and advanced glycation end products (AGEs)-specific fluorescence showed that MG-mediated protein modification was enhanced dose-dependently by CA (P<.05), whereas α-lipoic acid, glutathione and EDTA inhibited these changes. Electron paramagnetic resonance spectra showed that CA increased reactive oxygen species (ROS) production during glycation, suggesting the proglycation mechanism of CA is associated with its pro-oxidative properties. Additionally, fetal bovine serum (FBS) was utilized as the source of target proteins for evaluating the effects of CA in cells. Differential glycation of FBS samples was performed by incubating FBS with MG, CA or aminoguanidine (AG, an AGE inhibitor). FBS incubated with MG and CA (MG/CA-FBS) evoked the greatest deleterious responses, as follows: (1) inducing proinflammatory tumor necrosis factor (TNF)-α and interleukin-1β expression and ROS production in monocytic THP-1 cells, (2) stimulating TNF-α secretion in RAW 264.7 macrophages and (3) causing oxidative DNA damage and inducing the expression of receptor for AGEs (RAGE), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 in human umbilical vein endothelial cells. Furthermore, adhesion and transendothelial migration of monocytes were also significantly increased by MG/CA-FBS treatment compared to MG-FBS (P<.05). In conclusion, our data show that CA exhibits pro-oxidative and pro-glycative effects during the glycation process, suggesting a detrimental role for CA under high-glycotoxin conditions.