Genotoxicity of instant coffee: possible involvement of phenolic compounds

Genotoxic Assessment of the Dry Decoction of Myracrodruon urundeuva Allemão (Anacardiaceae) Leaves in Somatic Cells of Drosophila melanogaster by the Comet and SMART Assays

Medicinal plants are worldwide used as an efficient treatment of many diseases. Myracrodruon urundeuva Allemão (Anacardiaceae) is widely used Brazilian folk medicine to treat inflammations and infections of the female genital tract, conditions of the stomach and throat, and to heal wounds on the skin and mucous membranes. Several pharmacological properties of extracts and compounds isolated from M. urundeuva are found in the literature, corroborating its uses as antiulcer and gastroprotective, anti-inflammatory and analgesic, as well as antimicrobial. Despite these many uses in traditional herbal medicine, there are few reports of its toxic-genetic effect. This work aimed to investigate the genotoxic and mutagenic potential in vivo of the dry decoction of M. urundeuva leaves on somatic cells of Drosophila melanogaster, through the Comet assay and somatic mutation and recombination test (SMART). Six concentrations (0.5, 1.0, 2.0, 4.0, 8.0, and 16.0 mg/mL) were studied after feeding individuals for 24 hr in culture medium hydrated with extracts of M. urundeuva. In the Comet assay, all concentrations showed a genotoxic effect significantly higher than the negative control group, treated with distilled water. The two highest concentrations were also superior to the positive control group, treated with cyclophosphamide (1 mg/mL). In the SMART, there was a mutagenic effect at all concentrations tested, with a clear dose-dependent relationship. Both recombination and mutation account for these mutagenic effects. The set of results indicate that the dry decoction of M. urundeuva leaves is genotoxic and mutagenic for D. melanogaster under the experimental conditions of this study. Environ. Mol. Mutagen. 61:329-337, 2020. © 2019 Wiley Periodicals, Inc.

Chemical Constituents of the Ethyl Acetate Extract from Diaphragma juglandis Fructus and Their Inhibitory Activity on Nitric Oxide Production In Vitro

Diaphragma juglandis fructus contains various bioactive constituents. Fourteen compounds were isolated from Diaphragma juglandis fructus by preparative high performance liquid chromatography (pre-HPLC) and high-speed counter-current chromatography (HSCCC). Their structures were identified by nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS). Compounds (+)-dehydrovomifoliol (12), (6R,9R)-9-hydroxymegastigman-4-en-3-one (13) and (6R,9S)-9-hydroxymegastigman-4-en-3-one (14) are found from Juglans regia L. for the first time. Compounds dihydrophaseic acid (2), blumenol B (3) and (4S)-4-hydroxy-1-tetralone (11) are isolated from Diaphragma juglandis fructus for the first time. The anti-inflammatory effects of isolated compounds were evaluated by an in vitro model of lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Compounds gallic acid (1), ethyl gallate (9) and (+)-dehydrovomifoliol (12) exhibited inhibitory activity on the nitric oxide production of RAW 264.7 at a concentration of 25 μM. The result indicated that the combination HSCCC with pre-HPLC is an effective way for compound separation and purification. And Diaphragma juglandis fructus constituents have the potential for the treatment of inflammatory-related diseases.

Impacts of discarded coffee waste on human and environmental health

Coffee is one of the most widely consumed beverages throughout the world. So far, many studies have shown the properties of coffee beverages, but little is known about its impacts on human and environmental health from its discard in the environment. So, the present work aims to investigate the mutagenic, genotoxic, cytotoxic and ecotoxic effects of leached (LE) and solubilized (SE) extracts from coffee waste, simulating the disposal of this residue in landfills and via sewage systems, respectively. Chemical analyses were also carried out. LE and SE induced mutagenicity in the TA98 Salmonella strain with and without exogenous metabolization (S9). In the TA100 only SE induced mutagenicity, what was observed without S9. An increase in the frequency of micronuclei was observed in HepG2 cell line after 3 and 24h of exposure to both extracts. No cytotoxic effects were observed in HepG2 cells by WST-1 assay. The EC50 values for the LE and SE were 1.5% and 11.26% for Daphnia similis, 0.12% and 1.39% for Ceriodaphnia dubia and 6.0% and 5.5% for Vibrio fischeri, respectively. Caffeine and several transition metals were found in both extracts. Coffee waste discarded in the environment may pose a risk to human and environmental health, since this compound can cause DNA damage and present toxicity to aquatic organisms.

Pharmacologic overview of systemic chlorogenic acid therapy on experimental wound healing

Chlorogenic acid (CGA) is a well-known natural antioxidant in human diet. To understand the effects of CGA on wound healing by enhancing antioxidant defense in the body, the present study sought to investigate the potential role of systemic CGA therapy on wound healing and oxidative stress markers of the skin. We also aimed to understand whether chronic CGA treatment has side effects on pivotal organs or rat bone marrow during therapy. Full-thickness experimental wounds were created on the backs of rats. CGA (25, 50, 100, 200 mg/kg) or vehicle was administered intraperitoneally for 15 days. All rats were sacrificed on the 16th day. Biochemical, histopathological, and immunohistochemical examinations were performed. Possible side effects were also investigated. The results suggested that CGA accelerated wound healing in a dose-dependent manner. CGA enhanced hydroxyproline content, decreased malondialdehyde and nitric oxide levels. and elevated reduced glutathione, superoxide dismutase, and catalase levels in wound tissues. Epithelialization, angiogenesis, fibroblast proliferation, and collagen formation increased by CGA while polymorph nuclear leukocytes infiltration decreased. CGA modulated matrix metalloproteinase-9 and tissue inhibitor-2 expression in biopsies. Otherwise, high dose of CGA increased lipid peroxidation of liver and kidney without affecting the heart and muscle samples. Chronic CGA increased micronuclei formation and induced cytotoxicity in the bone marrow. In conclusion, systemic CGA has beneficial effects in improving wound repair. Antioxidant, free radical scavenger, angiogenesis, and anti-inflammatory effects of CGA may ameliorate wound healing. High dose of CGA may induce side effects. In light of these observations, CGA supplementation or dietary CGA may have benefit on wound healing.

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.

Assessment of the genotoxicity of olive mill waste water (OMWW) with the Vicia faba micronucleus test

The present study concerns the genotoxicity of olive mill waste water (OMWW) generated in mills producing olive oil in Morocco. The Vicia faba micronucleus test was used to evaluate the genotoxicity of OMWW and the six major phenolic compounds identified by HPLC in this effluent. Five dilutions of OMWW were tested: 0.1, 1, 5, 10 and 20%. Maleic hydrazide was used as a positive control. The results showed that OMWW was genotoxic at 10% dilution. In order to investigate the components involved in this genotoxicity, the six major phenols present in this effluent, oleuropein, gallic acid, 4-hydroxyphenyl acetic acid, caffeic acid, paracoumaric acid and veratric acid, were studied at concentrations corresponding to the genotoxic concentration of the OMWW itself. Two phenols, gallic acid and oleuropein induced a significant increase in micronucleus frequency in Vicia faba; the four other phenols had no significant genotoxic effect. These results suggest that under the experimental conditions of our assay, OMWW genotoxicity was associated with gallic acid and oleuropein.

Assessment of the DNA damaging potency and chemopreventive effects towards BaP-induced genotoxicity in human derived cells by Monimiastrum globosum, an endemic Mauritian plant

Naturally occurring compounds have protective effects towards mutagens and carcinogens. The leaf extract of Monimiastrum globosum (Bois de Clous), a Mauritian endemic plant from the Myrtaceae family, was studied for its potency to induce DNA damage in human HepG2 hepatoma cells using DNA migration as a biological endpoint in the alkaline single cell gel electrophoresis (SCGE) assay. This was contrasted with the ability to modulate the benzo[a]pyrene (BaP)-dependent DNA damage in human hepatoma cells. M. globosum caused genotoxicity in HepG2 cells at concentrations exceeding 3mg fresh weight (FW) per ml cell culture in the absence of cytotoxicity. Pre-treatment of the cells with 12.2 microg FW/ml to 1.56 mg FW/ml led to a pronounced antigenotoxic effect towards BaP-induced DNA damage. DNA migration (OTM) was reduced by 66%, 81.5% and 74% for 49, 98 and 195 microg FW/ml, respectively. A U-shaped dose-response curve was derived for M. globosum indicating genotoxic effects in high doses and antigenotoxic effects in low doses. M. globosum extract had total phenolics (15 mg/g FW) with flavonoids (aglycones and conjugates: 8 mg/g FW) and proanthocyanidins (3mg/g FW) as major phenolic subclasses. The hydrolysis of conjugated flavonoids yielded the aglycones quercetin (606 microg/g FW) and kaempferol (117.8 microg/g FW) while HPLC-MS/MS analysis of the total extract revealed free flavonoids such as quercetin (19.2 microg/g FW) and myricetin (2.5 microg/g FW). The antioxidant activity of the extract of M. globosum, assessed by the FRAP and TEAC assays yielded values of 275+/-3.82 micromol/g FW and 346+/-4.2 micromol/g FW, respectively.

Cloning and heterologous expression of hematin-dependent catalase produced by Lactobacillus plantarum CNRZ 1228

Lactobacillus plantarum CNRZ 1228 exhibited heme-dependent catalase activity under environmental conditions similar to those encountered during sausage fermentation. The 1,455-bp catalase gene (katL) was cloned and encoded a protein of 484 amino acids. Expression of katL in a heterologous host showed that katL encodes a functional catalase. PCR screening of selected strains of lactic acid bacteria for katL indicated the presence of similar genes in other strains of lactobacilli.

Induction of chromosomal aberrations by phenolic compounds: possible role of reactive oxygen species

Phenolic molecules are widely present in the environment and some of them are well known carcinogens. Some phenolic molecules are also genotoxic but the mechanisms involved in this process are not fully understood. We have studied the induction of chromosomal aberrations by phenol, catechol and pyrogallol in V79 cells at different pH values (6.0, 7.4 and 8.0). At the same pH values, the production of hydroxyl radicals was assessed by measuring the degradation of deoxyribose. Apart from phenol, which only induces a non-significant increase in chromosomal aberration in this experimental system, catechol and pyrogallol showed clear clastogenic effect in a pH-dependent way. Experiments carried out at pH 7.4 in the presence of S9 Mix, SOD, catalase and catalase + SOD suggest that the formation of reactive oxygen species is not the main mechanism involved in the genotoxicity of catechol. However, concerning pyrogallol, our results suggest that its genotoxicity is almost exclusively mediated by reactive oxygen species. Taken together, these results suggest that, in spite of the structural similarity between the different molecules studied, the mechanisms of genotoxicity of these molecules could be considerably different. The existence of several mechanisms of genotoxicity, partially shared by this class of compounds, could explain the synergistic effects observed between these compounds in several genotoxicity test systems. Accurate knowledge of their mechanisms of genotoxicity could improve considerably the assessment of their relevance to human health, since these compounds, once absorbed, are subject to a wide range of pH values in vivo.

Selective peroxynitrite scavenging activity of 3-methyl-1,2-cyclopentanedione from coffee extract

It has been known that reactive oxygen and nitrogen species such as nitric oxide (NO), superoxide radical (*O2-) and their byproduct peroxynitrite (ONOO-) induce cellular and tissue injury, ultimately resulting in several human diseases. In this study, we examined scavenging effects of 3-methyl-1,2-cyclopentanedione (MCP) from coffee extract on the reactivity of those toxic molecules. MCP significantly inhibited both the oxidation of 2,7-dichlorodihydrofluorescein diacetate (H2DCFDA) by reactive oxygen species (ROS) (mainly *O2-) from kidney homogenate (41% at 100 microM) and the generation of fluorescent 4,5-diaminofluorescein (DAF-2) by NO from sodium nitroprusside (IC50 (concn producing 50% inhibition), 63.8 microM). More potently, however, MCP suppressed the oxidation of dihydrorhodamine 123 (DHR 123) to fluorescent rhodamine 123 mediated by authentic ONOO- with an IC50 value of 3.3 microM. The neutralizing effect of the reactivity of ONOO- by MCP was due to electron donation, not nitration of the compound. Additionally, MCP also decreased ONOO- formation of nitrotyrosine adducts of glutathione (GSH) reductase, and consequently protected the enzyme activity of GSH reductase against decreasing by ONOO-, indicating that MCP may prevent ONOO- -induced damage of GSH reductase. Furthermore, MCP only weakly suppressed NO production, which is one of the upstream sources of ONOO- in-vivo, suggesting that NO production may be not a pharmacological target for MCP. Taken together, our results suggest that MCP may be regarded as a selective regulator of ONOO- -mediated diseases via direct scavenging activity of ONOO-.

Sister chromatid exchange induced by several types of coffees in Chinese hamster ovary cells

Different brands of commercial caffeinated and decaffeinated coffees (roasted, high roast, blend ground, and instant coffees) were studied. These coffees were tested for their ability to induce sister chromatid exchanges (SCE) in CHO-K1 cells. Tests were performed in the presence and in the absence of a metabolic activation system (S-9 mix). Results were compared to the roasting procedure because genotoxic products could be formed from these processes. Our results indicate that caffeinated instant coffees showed higher genotoxic activity than decaffeinated coffees. Non-significant genotoxic activity was detected with the green coffee (unroasted). The highest increase of the frequency of SCE occurred when the caffeinated instant coffee was tested in the absence of metabolic activation system. The repeatability of the test was checked through three assays with the same sample.

Genotoxicity of instant coffee and of some phenolic compounds present in coffee upon nitrosation

Instant coffee exhibits genotoxic activity upon nitrosation at acidic pH values in the Ames tester strain TA100. Using adsorption chromatography (Amberlit XAD-2) it was observed that the major fraction of molecules responsible for the genotoxic activity upon nitrosation was not retained on this resin, suggesting that the polar molecules present in instant coffee could be responsible for the genotoxicity observed upon nitrosation. Some phenolic molecules present in instant coffee (catechol, caffeic acid, and chlorogenic acid) were also genotoxic upon nitrosation under the same experimental conditions. The concentrations of nitrosatable phenolic compounds in the studied coffee were determined by HPLC and their contributions to the total genotoxicity observed were studied. The results obtained suggest that besides phenolic compounds other molecules were also involved in the genotoxicity of this beverage upon nitrosation. Teratogenesis Carcinog. Mutagen. 20:241-249, 2000.

Coffee drinking increases levels of urinary hydrogen peroxide detected in healthy human volunteers

Freshly-voided human urine contains significant concentrations of hydrogen peroxide (H2O2). This H2O2 appears to arise in whole or in part by superoxide-dependent autoxidation of urinary biomolecules. Since instant coffee also contains high levels of H2O2, we examined the effect of coffee drinking on urinary levels of H2O2. Studies on healthy human volunteers showed that coffee drinking is rapidly and reproducibly followed by increased levels of H2O2 detectable in the urine for up to 2 h after drinking the coffee. The levels of H2O2 detected in urine suggest that exposure of human tissues to H2O2 may be greater than is commonly supposed. It is possible that H2O2 in urine could act as an antibacterial agent, and that H2O2 is involved in the regulation of glomerular function.