241 results found
Cohen SM, Eisenbrand G, Fukushima S, et al., 2021, FEMA GRAS assessment of natural flavor complexes: Origanum oil, thyme oil and related phenol derivative-containing flavoring ingredients., Food and Chemical Toxicology, Vol: 155, Pages: 1-18, ISSN: 0278-6915
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients, mostly consisting of a variety of essential oils and botanical extracts. This publication, seventh in the series, re-evaluates NFCs with constituent profiles dominated by phenolic derivatives including carvacrol, thymol and related compounds using a constituent-based procedure first published in 2005 and updated in 2018. The procedure is based on the chemical characterization of each NFC as intended for commerce and the estimated intake of the constituent congeneric groups. The procedure applies the threshold of toxicological concern (TTC) concept and evaluates relevant data on absorption, metabolism, genotoxic potential and toxicology of the constituent congeneric groups and the NFC under evaluation. Herein, the FEMA Expert Panel affirmed the generally recognized as safe (GRAS) status of seven phenolic derivative-based NFCs, Origanum Oil (Extractive) (FEMA 2828), Savory Summer Oil (FEMA 3013), Savory Summer Oleoresin (FEMA 3014), Savory Winter Oil (FEMA 3016), Savory Winter Oleoresin (FEMA 3017), Thyme Oil (FEMA 3064) and Thyme White Oil (FEMA 3065) under their conditions of intended use as flavor ingredients.
Eisenbrand G, Cohen SM, Fukushima S, et al., 2021, FEMA GRAS assessment of natural flavor complexes: Eucalyptus oil and other cyclic ether-containing flavoring ingredients, Food and Chemical Toxicology, Vol: 155, ISSN: 0278-6915
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a program for the re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients. This publication, the sixth in the series, will summarize the re-evaluation of eight NFCs whose constituent profiles are characterized by significant amounts of eucalyptol and/or other cyclic ethers. This re-evaluation was based on a procedure first published in 2005 and subsequently updated in 2018 that evaluates the safety of naturally occurring mixtures for their intended use as flavoring ingredients. The procedure relies on a complete chemical characterization of the NFC intended for commerce and the organization of its chemical constituents into well-defined congeneric groups. The safety of the NFC is evaluated using the well-established and conservative threshold of toxicological concern (TTC) concept in addition to data on absorption, metabolism and toxicology of the constituents of the congeneric groups and the NFC under evaluation. Eight NFCs derived from the Eucalyptus, Melaleuca, Origanum, Laurus, Rosmarinus and Salvia genera were affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavor ingredients based on an evaluation of each NFC and the constituents and congeneric groups therein.
Alotaibi A, Li J, Gooderham N, 2021, Tumour necrosis factor-α (TNF-α) enhances dietary carcinogen-induced DNA damage in colorectal cancer epithelial cells through activation of JNK signaling pathway, Toxicology, Vol: 457, ISSN: 0300-483X
Colorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer death. Benzo[a]pyrene (BaP) and 2-amino-1-methyl-6-phenylimidazol [4,5-b] pyridine (PhIP) present in cooked meat are pro-carcinogens and considered to be potential risk factors for CRC. Their carcinogenic and mutagenic effects require metabolic activation primarily by cytochrome P450 1 family enzymes (CYPs); the expression of these enzymes can be modulated by aryl hydrocarbon receptor (AhR) activation and the tumour microenvironment, involving mediators of inflammation. In this study, we hypothesized that tumour necrosis factor-α (TNF-α), a key mediator of inflammation, modulates BaP- and PhIP-induced DNA damage in colon cancer epithelial cells. Importantly, we observed that TNF-α alone (0.1–100 pg/ml) induced DNA damage (micronuclei formation) in HCT-116 cells and co-treatment of TNF-α with BaP or PhIP showed higher levels of DNA damage compared to the individual single treatments. TNF-α alone or in combination with BaP or PhIP did not affect the expression levels of CYP1A1 and CYP1B1 (target genes of AhR signaling pathways). The DNA damage induced by TNF-α was elevated in p53 null HTC-116 cells compared to wild type cells, suggesting that TNF-α-induced DNA damage is suppressed by functional p53. In contrast, p53 status failed to affect BaP and PhIP induced micronucleus frequency. Furthermore, JNK and NF-κB signaling pathway were activated by TNF-α treatment but only inhibition of JNK significantly reduced TNF-α-induced DNA damage. Collectively, these findings suggest that TNF-α induced DNA damage involves JNK signaling pathway rather than AhR and NF-κB pathways in colon cancer epithelial cells.
Li J, 2021, Roux-en-Y Gastric bypass-induced bacterial perturbation contributes to altered host-bacterial co-metabolic phenotype, Microbiome, Vol: 9, ISSN: 2049-2618
BACKGROUND: Bariatric surgery, used to achieve effective weight loss in individuals with severe obesity, modifies the gut microbiota and systemic metabolism in both humans and animal models. The aim of the current study was to understand better the metabolic functions of the altered gut microbiome by conducting deep phenotyping of bariatric surgery patients and bacterial culturing to investigate causality of the metabolic observations. METHODS: Three bariatric cohorts (n = 84, n = 14 and n = 9) with patients who had undergone Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) or laparoscopic gastric banding (LGB), respectively, were enrolled. Metabolic and 16S rRNA bacterial profiles were compared between pre- and post-surgery. Faeces from RYGB patients and bacterial isolates were cultured to experimentally associate the observed metabolic changes in biofluids with the altered gut microbiome. RESULTS: Compared to SG and LGB, RYGB induced the greatest weight loss and most profound metabolic and bacterial changes. RYGB patients showed increased aromatic amino acids-based host-bacterial co-metabolism, resulting in increased urinary excretion of 4-hydroxyphenylacetate, phenylacetylglutamine, 4-cresyl sulphate and indoxyl sulphate, and increased faecal excretion of tyramine and phenylacetate. Bacterial degradation of choline was increased as evidenced by altered urinary trimethylamine-N-oxide and dimethylamine excretion and faecal concentrations of dimethylamine. RYGB patients' bacteria had a greater capacity to produce tyramine from tyrosine, phenylalanine to phenylacetate and tryptophan to indole and tryptamine, compared to the microbiota from non-surgery, normal weight individuals. 3-Hydroxydicarboxylic acid metabolism and urinary excretion of primary bile acids, serum BCAAs and dimethyl sulfone were also perturbed following bariatric surgery. CONCLUSION: Altered bacterial composition and metabolism contribute to metabolic observations in biofluid
Fukushima S, Cohen SM, Eisenbrand G, et al., 2020, FEMA GRAS assessment of natural flavor complexes: Lavender, Guaiac Coriander-derived and related flavoring ingredients, Food and Chemical Toxicology, Vol: 145, Pages: 1-24, ISSN: 0278-6915
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a program for the re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients. This publication, fifth in the series, evaluates the safety of NFCs containing linalool and/or other characteristic mono- and sesquiterpenoid tertiary alcohols and esters using the safety evaluation procedure published by the FEMA Expert Panel in 2005 and updated in 2018. The procedure relies on a complete chemical characterization of the NFC intended for commerce and organization of the chemical constituents of each NFC into well-defined congeneric groups. The safety of each NFC is evaluated using the well-established and conservative threshold of toxicological concern (TTC) concept in addition to data on absorption, metabolism and toxicology of both the constituent congeneric groups and the NFCs. Sixteen NFCs, derived from the Lavandula, Aniba, Elettaria, Daucus, Salvia, Coriandrum, Ribes, Guaiacum/Bulnesia, Citrus, Pogostemon, Melaleuca and Michelia genera, were affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavor ingredients based on an evaluation of each NFC and the constituents and congeneric groups therein.
Gooderham NJ, Cohen SM, Eisenbrand G, et al., 2020, FEMA GRAS assessment of natural flavor complexes: Clove, Cinnamon leaf and West Indian bay leaf-derived flavoring ingredients, Food and Chemical Toxicology, Vol: 145, Pages: 1-16, ISSN: 0278-6915
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association initiated the safety re-evaluation of over 250 natural flavor complexes (NFCs) used as flavor ingredients. This publication, 4th in a series focusing on the safety evaluation of NFCs, presents an evaluation of NFCs rich in hydroxyallylbenzene and hydroxypropenylbenzene constituents using a procedure initially published in 2005 and updated in 2018 that evaluates the safety of naturally occurring mixtures for their intended use as flavoring ingredients. The procedure requires the characterization of the chemical composition for each NFC and subsequent organization of the constituents into defined congeneric groups. The safety of each NFC is evaluated using the conservative threshold of toxicological concern (TTC) approach together with studies on absorption, metabolism and toxicology of the NFC and its constituent congeneric groups. By the application of this procedure, seven NFCs, derived from clove, cinnamon leaf and West Indian bay leaf were affirmed as “generally recognized as safe (GRAS)” under their conditions of intended use as flavor ingredients. An eighth NFC, an oleoresin of West Indian bay leaf, was affirmed based on its estimated intake, which is below the TTC of 0.15 μg/person per day for compounds with structural alerts for genotoxicity.
Butler A, Ramachandran V, Cunningham T, et al., 2020, Increased MicroRNA levels in women with polycystic ovarian syndrome but without insulin resistance: a pilot prospective study, Frontiers in Endocrinology, Vol: 11, ISSN: 1664-2392
Background: Small noncoding microRNA (miRNA) have regulatory functions in polycystic ovary syndrome (PCOS) that differ to those in women without PCOS. However, little is known about miRNA expression in women with PCOS who are not insulin resistant (IR).Methods: Circulating miRNAs were measured using quantitative polymerase chain reaction (qPCR) in 24 non-obese BMI and age matched women with PCOS and 24 control women. A miRNA data set was used to determine miRNA levels.Results: Women with PCOS showed a higher free androgen index (FAI) and anti-mullerian hormone (AMH) but IR did not differ. Four miRNAs (miR-1260a, miR-18b-5p, miR-424-5p, and miR let-7b-3p) differed between control and PCOS women that passed the false discovery rate (FDR) out of a total of 177 circulating miRNAs that were detected. MiRNA let-7b-3p correlated with AMH in PCOS (p < 0.05). When the groups were combined, miR-1260a correlated with FAI and let-7b-3p correlated with body mass index (BMI) (p < 0.05). There was no correlation to androgen levels. Ingenuity pathway analysis showed that nine of the top 10 miRNAs reported were associated with inflammatory pathways.Conclusion: When IR did not differ between PCOS and control women, only four miRNA differed significantly suggesting that IR may be a driver for many of the miRNA changes reported. Let-7b-3p was related to AMH in PCOS, and to BMI as a group, whilst miR-1260a correlated with FAI. Androgen levels, however, had no effect upon circulating miRNA profiles. The expressed miRNAs were associated with the inflammatory pathway involving TNF and IL6.
Butler AE, Ramachandran V, Sathyapalan T, et al., 2020, Corrigendum: microRNA Expression in Women With and Without Polycystic Ovarian Syndrome Matched for Body Mass Index, Frontiers in Endocrinology, Vol: 11, Pages: 1-1, ISSN: 1664-2392
Butler AE, Ramachandran V, Sathypalan T, et al., 2020, microRNA expression in women with and without polycystic ovarian syndrome matched for body mass index, Frontiers in Endocrinology, Vol: 11, Pages: 1-8, ISSN: 1664-2392
Background: Despite several authors who have hypothesized that alterations of smallnoncoding RNAs (miR) are implicated in the etiopathogenesis of polycystic ovariansyndrome (PCOS), contrasting findings have been reported so far. Discrepancies in bodymass index (BMI) levels may account for these differences; therefore, the aim of thepresent study was to determine whether miR differed in serum samples collected fromage- and BMI-matched control and PCOS women.Methods: In a cross-sectional study, miR were measured using quantitative polymerasechain reaction in 29 women with anovulatory PCOS women and 29 control women whowere in the follicular phase of their menstrual cycle, from the local biobank.Results: One hundred seventy-six miR were detected, of which 15 miR passed the falsediscovery rate (FDR; p < 0.05) that differed between PCOS and control women. Therewas no association of the top 9 miR (p < 0.02) (miR-486-5p, miR-24-3p, miR-19b-3p,miR-22-3p, miR-19a-3p, miR-339-5p, miR-185-5p, miR-101-3p, miR-let-7i-5p) withBMI, androgen levels, insulin resistance, or antimullerian hormone (AMH) in eitherPCOS or normal women. Ingenuity pathway assessment showed the pathways wereinterrelated for abnormalities of the reproductive system.Conclusion: When the confounding influence of weight was accounted for, miR levelsdiffered between anovulatory PCOS women and control women in the follicular phase ofthe menstrual cycle. Interestingly, the differing miR were associated with the pathways ofreproductive abnormalities but did not associate with AMH or metabolic parameters.
Gooderham NJ, Cohen SM, Eisenbrand G, et al., 2020, The safety evaluation of food flavoring substances: the role of genotoxicity studies, Critical Reviews in Toxicology, Vol: 50, Pages: 1-27, ISSN: 1040-8444
The Flavor and Extract Manufacturers Association (FEMA) Expert Panel relies on the weight of evidence from all available data in the safety evaluation of flavoring substances. This process includes data from genotoxicity studies designed to assess the potential of a chemical agent to react with DNA or otherwise cause changes to DNA, either in vitro or in vivo. The Panel has reviewed a large number of in vitro and in vivo genotoxicity studies during the course of its ongoing safety evaluations of flavorings. The adherence of genotoxicity studies to standardized protocols and guidelines, the biological relevance of the results from those studies, and the human relevance of these studies are all important considerations in assessing whether the results raise specific concerns for genotoxic potential. The Panel evaluates genotoxicity studies not only for evidence of genotoxicity hazard, but also for the probability of risk to the consumer in the context of exposure from their use as flavoring substances. The majority of flavoring substances have given no indication of genotoxic potential in studies evaluated by the FEMA Expert Panel. Examples illustrating the assessment of genotoxicity data for flavoring substances and the consideration of the factors noted above are provided. The weight of evidence approach adopted by the FEMA Expert Panel leads to a rational assessment of risk associated with consumer intake of flavoring substances under the conditions of use.
Cohen SM, Eisenbrand G, Fukushima S, et al., 2020, FEMA GRAS assessment of natural flavor complexes: Mint, buchu, dill and caraway derived flavoring ingredients, Food and Chemical Toxicology, Vol: 135, ISSN: 0278-6915
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients. NFC flavor materials include a variety of essential oils and botanical extracts. The re-evaluation of NFCs is conducted based on a constituent-based procedure outlined in 2005 and updated in 2018 to evaluate the safety of NFCs for their intended use as flavor ingredients. This procedure is applied in the re-evaluation of the generally recognized as safe (GRAS) status of NFCs with constituent profiles that are dominated by alicyclic ketones such as menthone and carvone, secondary alcohols such as menthol and carveol, and related compounds. The FEMA Expert Panel affirmed the GRAS status of Peppermint Oil (FEMA 2848), Spearmint Oil (FEMA 3032), Spearmint Extract (FEMA 3031), Cornmint Oil (FEMA 4219), Erospicata Oil (FEMA 4777), Curly Mint Oil (FEMA 4778), Pennyroyal Oil (FEMA 2839), Buchu Leaves Oil (FEMA 2169), Caraway Oil (FEMA 2238) and Dill Oil (FEMA 2383) and determined FEMA GRAS status for Buchu Leaves Extract (FEMA 4923), Peppermint Oil, Terpeneless (FEMA 4924) and Spearmint Oil, Terpeneless (FEMA 4925).
Rietjens IMCM, Cohen SM, Eisenbrand G, et al., 2020, FEMA GRAS assessment of natural flavor complexes: Cinnamomum and Myroxylon-derived flavoring ingredients, Food and Chemical Toxicology, Vol: 135, ISSN: 0278-6915
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a program for the re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients. This publication, third in the series, considers NFCs composed primarily of constituents with the 3-phenyl-2-propenyl or a cinnamyl functional group, using the procedure outlined in 2005 and updated in 2018 to evaluate the safety of naturally-occurring mixtures for their intended use as flavor ingredients. The procedure relies on a complete chemical characterization of the NFC intended for commerce and organization of each NFC's chemical constituents into well-defined congeneric groups. The safety of the NFC is evaluated using the well-established and conservative threshold of toxicological concern (TTC) concept in addition to data on absorption, metabolism, and toxicology of members of the congeneric groups and the NFC under evaluation. Six NFCs from the Myroxylon and Cinnamomum genera, Balsam Oil, Peru (FEMA 2117), Tolu Balsam Extract (FEMA 3069), Cassia Bark Extract (FEMA 2257), Cassia Bark Oil (FEMA 2258), Cinnamon Bark Extract (FEMA 2290) and Cinnamon Bark Oil (FEMA 2291) were evaluated and affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavor ingredients.
Malik D-E-S, David R, Gooderham N, 2019, Interleukin-6 selectively induces drug metabolism to potentiate the genotoxicity of dietary carcinogens in mammary cells, Archives of Toxicology, Vol: 93, Pages: 3005-3020, ISSN: 0340-5761
Breast cancer is the most commonly diagnosed malignancy in females, the aetiology beingmultifactorial and includes the role of lifestyle exposure to DNA damaging chemicals such asdietary carcinogens benzo (a) pyrene (BaP) and 2-amino-1-methyl-6-phenylimidazo [4, 5-b]pyridine (PhIP). Both compounds require cytochrome P450 (CYP) mediated metabolic activationto DNA damaging species, and both induce transcriptional responses through the nuclearreceptors Aryl hydrocarbon receptor (AhR) and estrogen receptor α (ERα). BaP and PhIP aremammary carcinogens in rodents. Clinically, circulating IL-6 expression is linked with poorprognosis of cancer and 35% of the deaths in breast cancer are linked with inflammation. Theobjective of this work was to investigate the molecular toxicology and local activation of BaP andPhIP in the presence of IL-6. Our laboratory has previously reported that miR27b can regulateCYP1B1 expression in colorectal cells, here we have investigated if this mechanism is working inmammary cell models, MCF-7 and MDA-MB-231 cells. Treatment (24h) of cells with BaP (10nM10µM) and PhIP (100nM-100µM) significantly induced genetic damage (micronuclei formation) ina dose dependent manner in both cell lines. This effect was potentiated in the presence humanIL-6 at concentrations reported to be expressed in clinical breast cancer. On its own, IL-6treatment failed to induce micronuclei frequency above control levels in these cells. Compared toBaP or PhIP treatment alone, IL-6 plus BaP or PhIP, selectively induced CYP1B1 significantly inboth cell lines. Additionally, miR27b expression was downregulated by IL-6 treatments andtransfection with miR27b inhibitor confirmed that miR27b is a regulator of CYP1B1 in both celllines. These data show that BaP- and PhIP-induced DNA damage in mammary cells is potentiatedby the inflammatory cytokine IL-6 and that inflammation-induced CYP expression, specificallyCYP1B1 via miR27b, is responsible for this effect.
Gooderham N, Alkandari A, Ashrafian H, et al., 2019, Bariatric surgery modulates urinary levels of microRNAs involved in the regulation of renal function, Frontiers in Endocrinology, Vol: 10, ISSN: 1664-2392
Background: Obesity and diabetes cause chronic kidney disease with a common pathophysiology that is characterized by the accumulation of collagen in the extracellular matrix. Recent evidence has implicated the epithelial-to-mesenchymal transition (EMT) as a key step in this pathology with regulation by microRNAs. Weight loss leads to improvements in renal function; therefore, this study hypothesized that bariatric-surgery aided weight loss would lead to changes in urinary microRNAs involved in the regulation of renal function.Materials and methods: Twenty-four bariatric patients undergoing Roux-en-Y gastric bypass and sleeve gastrectomy donated urine pre-operatively and at 2–6 months and 1–2 years post-operatively. Urine samples were also obtained from 10 healthy weight and 7 morbidly obese non-surgical controls. Expression levels of kidney microRNAs were assessed in urine and the function of microRNAs was assessed through the in vitro transfection of HK-2 cells, a kidney proximal tubule cell line.Results: Levels of miR 192, miR 200a, and miR 200b were upregulated in urine following bariatric surgery. This increase was consistent across surgical type and diabetes status and was maintained and enhanced with time. Bariatric surgery alters urinary miR 192 expression from levels seen in morbidly obese patients to levels seen in healthy weight control patients. In mechanistic studies, the transfection of miR 192 in HK-2 cells increased miR 200a expression and decreased ZEB2, a key transcriptional promoter of kidney fibrosis.Conclusions: Bariatric surgery increased miR 192 and miR 200 urinary levels, key anti-fibrotic microRNAs that could contribute to a renal-protective mechanism and may be of value as urinary biomarkers following surgery. These findings suggest that urinary microRNAs may represent potential novel biomarkers for obesity-associated renal function.
Abdul Rahim MBH, Chilloux J, Martinez-Gili L, et al., 2019, Diet-induced metabolic changes of the human gut microbiome: importance of short-chain fatty acids, methylamines and indoles, Acta Diabetologica, Vol: 56, Pages: 493-500, ISSN: 0940-5429
The human gut is a home for more than 100 trillion bacteria, far more than all other microbial populations resident on the body's surface. The human gut microbiome is considered as a microbial organ symbiotically operating within the host. It is a collection of different cell lineages that are capable of communicating with each other and the host and has an ability to undergo self-replication for its repair and maintenance. As the gut microbiota is involved in many host processes including growth and development, an imbalance in its ecological composition may lead to disease and dysfunction in the human. Gut microbial degradation of nutrients produces bioactive metabolites that bind target receptors, activating signalling cascades, and modulating host metabolism. This review covers current findings on the nutritional and pharmacological roles of selective gut microbial metabolites, short-chain fatty acids, methylamines and indoles, as well as discussing nutritional interventions to modulate the microbiome.
Cohen SM, Eisenbrand G, Fukushima S, et al., 2019, FEMA GRAS assessment of natural flavor complexes: Citrus-derived flavoring ingredients, Food and Chemical Toxicology, Vol: 124, Pages: 192-218, ISSN: 0278-6915
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavoring ingredients. This publication is the first in a series and summarizes the evaluation of 54 Citrus-derived NFCs using the procedure outlined in Smith et al. (2005) and updated in Cohen et al. (2018) to evaluate the safety of naturally-occurring mixtures for their intended use as flavoring ingredients. The procedure relies on a complete chemical characterization of each NFC intended for commerce and organization of each NFC's chemical constituents into well-defined congeneric groups. The safety of the NFC is evaluated using the well-established and conservative threshold of toxicological concern (TTC) concept in addition to data on absorption, metabolism and toxicology of members of the congeneric groups and the NFC under evaluation. As a result of the application of the procedure, 54 natural flavor complexes derived from botanicals of the Citrus genus were affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavoring ingredients based on an evaluation of each NFC and the constituents and congeneric groups therein.
David RM, Gooderham NJ, 2018, Dose-dependent synergistic and antagonistic mutation responses of binary mixtures of the environmental carcinogen benzo[a]pyrene with food-derived carcinogens, Archives of Toxicology, Vol: 92, Pages: 3459-3469, ISSN: 0340-5761
Cooking food at high temperatures produces genotoxic chemicals and there is concern about their impact on human health. DNA damage caused by individual chemicals has been investigated but few studies have examined the consequences of exposure to mixtures as found in food. The current study examined the mutagenic response to binary mixtures of benzo[a]pyrene (BaP) with glycidamide (GA), BaP with acrylamide (AC), or 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) with GA at human-relevant concentrations (sub-nM). The metabolically competent human MCL-5 cells were exposed to these chemicals individually or in mixtures and mutagenicity was assessed at the thymidine kinase (TK) locus. Mixture exposures gave dose-responses that differed from those for the individual chemicals; for the BaP-containing mixtures, an increased mutation frequency (MF) at low concentration combinations that were not mutagenic individually, and decreased MF at higher concentration combinations, compared to the calculated predicted additive MF of the individual chemicals. In contrast, the mixture of PhIP with GA did not increase MF above background levels. These data suggest BaP is driving the mutation response and that metabolic activation plays a role; in mixtures with BaP the increased/decreased MF above/below the expected additive MF the order is PhIP > AC > GA. The increase in MF at some low concentration combinations that include BaP is interesting and supports our previous work showing a similar response for BaP with PhIP, confirming this response is not limited to the BaP/PhIP combination. Moreover, the lack of a mutation response for PhIP with GA relative to the response of the individual chemicals at equivalent doses is interesting and may represent a potential avenue for reducing the risk of exposure to environmental carcinogens; specifically, removal of BaP from the mixture may reduce the mutation effect, although in the context of food this wou
Malik D-E-S, David RM, Gooderham NJ, 2018, Mechanistic evidence that benzo[a]pyrene promotes an inflammatory microenvironment that drives the metastatic potential of human mammary cells, Archives of Toxicology, Vol: 92, Pages: 3223-3239, ISSN: 0340-5761
Benzo[a]pyrene (B(a)P) is a major cancer-causing contaminant present in food such as cooked meats and cereals, and is ubiquitous in the environment in smoke derived from the combustion of organic material. Exposure to B(a)P is epidemiologically linked with the incidence of breast cancer. Although B(a)P is recognized as a complete genotoxic carcinogen, thought to act primarily via CYP-mediated metabolic activation to DNA-damaging species, there is also evidence that B(a)P exposure elicits other biological responses that promote development of the cancer phenotype. Here in mechanistic studies using human mammary cells MCF-7 and MDA-MB-231, we have explored mechanisms whereby B(a)P (10- 8 to 10- 5M) promotes inflammation pathways via TNF-α and NFκB leading to IL-6 upregulation, microRNA (Let7a, miR21 and miR29b) dysregulation and activation of VEGF. The miRNA dysregulation is associated with altered expression of inflammation mediators and increased migration and invasive potential of human mammary cancer cells. Our data suggest that mammary cell exposure to B(a)P results in perturbation of inflammation mediators and dysregulation of tumorigenic miRNAs, leading to an inflammation microenvironment that facilitates migration and invasion of mammary epithelial cells. These properties of B(a)P, together with its well-established metabolic activation to DNA-damaging species, offer mechanistic insights into its carcinogenic mode of action.
Dumas M-E, Chilloux J, Myridakis A, et al., 2018, Microbiome inhibition of IRAK-4 by trimethylamine mediates metabolic and immune benefits in high fat diet-induced insulin resistance, 54th Annual Meeting of the European-Association-for-the-Study-of-Diabetes (EASD), Publisher: SPRINGER, Pages: S267-S268, ISSN: 0012-186X
Cohen SM, Gooderham N, 2018, GRAS 28 Flavouring Substances, Food Technology, ISSN: 0015-6639
Smith RL, Cohen SM, Fukushima S, et al., 2018, The safety evaluation of food flavouring substances: the role of metabolic studies, Toxicology Research, Vol: 7, Pages: 618-646, ISSN: 2045-452X
The safety assessment of a flavour substance examines several factors, including metabolic and physiological disposition data. The present article provides an overview of the metabolism and disposition of flavour substances by identifying general applicable principles of metabolism to illustrate how information on metabolic fate is taken into account in their safety evaluation. The metabolism of the majority of flavour substances involves both a series of enzymatic and non-enzymatic biotransformation that often result in products that are more hydrophilic and more readily excretable than their precursors. Flavours can undergo metabolic reactions, such as oxidation, reduction, or hydrolysis that alter a functional group relative to the parent compound. The altered functional group may serve as a reaction site for a subsequent metabolic transformation. Metabolic intermediates undergo conjugation with an endogenous agent such as glucuronic acid, sulphate, glutathione, amino acids, or acetate. Such conjugates are typically readily excreted through the kidneys and liver. This paper summarizes the types of metabolic reactions that have been documented for flavour substances that are added to the human food chain, the methodologies available for metabolic studies, and the factors that affect the metabolic fate of a flavour substance.
Cohen SM, Eisenbrand G, Fukushima S, et al., 2018, GRAS 28 FLAVORING SUBSTANCES, FOOD TECHNOLOGY, Vol: 72, Pages: 62-77, ISSN: 0015-6639
Alkandari A, Ashrafian H, Sathyapalan T, et al., 2018, Improved physiology and metabolic flux after Roux-en-Y gastric bypass is associated with temporal changes in the circulating microRNAome: a longitudinal study in humans., BMC Obesity, Vol: 5, ISSN: 2052-9538
BackgroundThe global pandemic of obesity and the metabolic syndrome are leading causes of mortality and morbidity. Bariatric surgery leads to sustained weight loss and improves obesity-associated morbidity including remission of type 2 diabetes. MicroRNAs are small, endogenous RNAs that regulate gene expression post-transcriptionally, controlling most of the human transcriptome and contributing to the regulation of systemic metabolism. This preliminary, longitudinal, repeat sampling study, in which subjects acted as their own control, aimed to assess the temporal effect of bariatric surgery on circulating microRNA expression profiles.MethodsWe used Exiqon’s optimized circulating microRNA panel (comprising 179 validated miRNAs) and miRCURY locked nucleic acid plasma/serum Polymerase Chain Reaction (PCR) to assess circulating microRNA expression. The microRNAome was determined for Roux-en-Y gastric bypass (RYGB) patients examined preoperatively and at 1 month, 3 months, 6 months, 9 months and 12 months postoperatively. Data was analysed using multivariate and univariate statistics.ResultsCompared to the preoperative circulating microRNA expression profile, RYGB altered the circulating microRNAome in a time dependent manner and the expression of 48 circulating microRNAs were significantly different. Importantly, these latter microRNAs are associated with pathways involved in regulation and rescue from metabolic dysfunction and correlated with BMI, the percentage of excess weight loss and fasting blood glucose levels.ConclusionsThe results of this pilot study show that RYGB fundamentally alters microRNA expression in circulation with a time-dependent progressive departure in profile from the preoperative baseline and indicate that microRNAs are potentially novel biomarkers for the benefits of bariatric surgery.
Malik D-E-S, David RM, Gooderham NJ, 2018, Ethanol potentiates the genotoxicity of the food-derived mammary carcinogen PhIP in human estrogen receptor-positive mammary cells: mechanistic support for lifestyle factors (cooked red meat and ethanol) associated with mammary cancer, Archives of Toxicology, Vol: 92, Pages: 1639-1655, ISSN: 0340-5761
Consumption of cooked/processed meat and ethanol are lifestyle risk factors in the aetiology of breast cancer. Cooking meat generates heterocyclic amines such as 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Epidemiology, mechanistic and animal studies indicate that PhIP is a mammary carcinogen that could be causally linked to breast cancer incidence; PhIP is DNA damaging, mutagenic and oestrogenic. PhIP toxicity involves cytochrome P450 (CYP1 family)-mediated metabolic activation to DNA-damaging species, and transcriptional responses through Aryl hydrocarbon receptor (AhR) and estrogen-receptor-α (ER-α). Ethanol consumption is a modifiable lifestyle factor strongly associated with breast cancer risk. Ethanol toxicity involves alcohol dehydrogenase metabolism to reactive acetaldehyde, and is also a substrate for CYP2E1, which when uncoupled generates reactive oxygen species (ROS) and DNA damage. Here, using human mammary cells that differ in estrogen-receptor status, we explore genotoxicity of PhIP and ethanol and mechanisms behind this toxicity. Treatment with PhIP (10-7-10-4 M) significantly induced genotoxicity (micronuclei formation) preferentially in ER-α positive human mammary cell lines (MCF-7, ER-α+) compared to MDA-MB-231 (ER-α-) cells. PhIP-induced CYP1A2 in both cell lines but CYP1B1 was selectively induced in ER-α(+) cells. ER-α inhibition in MCF-7 cells attenuated PhIP-mediated micronuclei formation and CYP1B1 induction. PhIP-induced CYP2E1 and ROS via ER-α-STAT-3 pathway, but only in ER-α (+) MCF-7 cells. Importantly, simultaneous treatments of physiological concentrations ethanol (10-3-10-1 M) with PhIP (10-7-10-4 M) increased oxidative stress and genotoxicity in MCF-7 cells, compared to the individual chemicals. Collectively, these data offer a mechanistic basis for the increased risk of breast cancer associated with dietary cooked meat and ethanol lifestyle choices.
Cohen SM, Eisenbrand G, Fukushima S, et al., 2018, Updated procedure for the safety evaluation of natural flavor complexes used as ingredients in food, Food and Chemical Toxicology, Vol: 113, Pages: 171-178, ISSN: 0278-6915
An effective and thorough approach for the safety evaluation of natural flavor complexes (NFCs) was published in 2005 by the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA). An updated procedure is provided here, which maintains the essential concepts of the use of the congeneric group approach and the reliance on the Threshold of Toxicological Concern (TTC) concept. The updated procedure emphasizes more rigorous considerations of unidentified constituents and the genotoxic potential of constituents. The update of the previously established procedure is the first step in a multi-year project to conduct safety re-evaluations for more than 250 NFCs that have uses that are currently considered Generally Recognized as Safe (GRAS) by the FEMA Expert Panel. In addition, this procedure can be more generally employed in the safety evaluation of NFCs.
Saleh AF, Bachman M, Priestley CC, et al., 2018, 2'-O-(2-methoxyethyl) nucleosides are not phosphorylated or incorporated into the genome of Human Lymphoblastoid TK6 Cells, Toxicological Sciences, Vol: 163, Pages: 70-78, ISSN: 1096-0929
Nucleoside analogues with 2'-modified sugar moieties are often used to improve the RNA target affinity and nuclease resistance of therapeutic oligonucleotides in preclinical and clinical development. Despite their enhanced nuclease resistance, oligonucleotides could slowly degrade releasing nucleoside analogues that have the potential to become phosphorylated and incorporated into cellular DNA and RNA. For the first time, the phosphorylation and DNA and RNA incorporation of 2'-O-(2-methoxyethyl) (2'-O-MOE) nucleoside analogues have been investigated. Using LC/MS/MS, we showed that enzymes in the nucleotide salvage pathway including deoxycytidine kinase (dCK) and thymidine kinase (TK1) displayed poor reactivity toward 2'-O-MOE nucleoside analogues. On the other hand, 2'-fluoro (F) nucleosides, regardless of the nucleobase, were efficiently phosphorylated to their monophosphate forms by dCK and TK1. Consistent with their efficient phosphorylation by dCK and TK1, 2'-F nucleosides analogues were incorporated into cellular DNA and RNA while no incorporation was detected with 2'-O-MOE nucleoside analogues. In conclusion, these data suggest that the inability of dCK and TK1 to create the monophosphates of 2'-O-MOE nucleoside analogues reduces the risk of their incorporation into cellular DNA and RNA.
Harling L, Athanasiou T, Ashrafian H, et al., 2017, Pre-operative serum VCAM-1 as a biomarker of atrial fibrillation after coronary artery bypass grafting, Journal of Cardiothoracic Surgery, Vol: 12, ISSN: 1749-8090
ObjectiveSystemic inflammation is a recognised contributory factor in the pathogenesis of de novo post-operative atrial fibrillation after cardiac surgery. This study aims to determine whether serum soluble vascular endothelial cell adhesion molecule (sVCAM-1) may predict the onset of POAF in patients under going coronary artery bypass grafting.Methods34 patients undergoing non-emergent, on-pump CABG were prospectively recruited. Plasma was obtained at 24 h pre-operatively and at 48 and 96 h post-operatively. POAF was defined by continuous Holter recording. Inter-group comparisons were performed using student t-test or ANOVA as appropriate.ResultsThirteen (13/34) patients developed POAF at a mean of 2.5 days post-operatively. Serum sVCAM-1 was significantly increased in the pre-operative serum of POAF when compared to non-POAF patients (p = 0.022). No significant difference was observed between the groups at 48 h (p = 0.073) or 96 h (p = 0.135) post-operatively. sVCAM-1 had a sensitivity of 60.0% and specificity of 77.27%, with an overall diagnostic accuracy of 75.2% in predicting POAF.ConclusionssVCAM-1 concentration in the pre-operative serum of patients undergoing CABG may accurately predict the onset of de novo POAF. As such, serum sVCAM-1 may be used as a predictive biomarker for this common arrhythmia. Further work must now perform prospective, targeted validation of these results in a larger patient cohort.
Kamola PJ, Maratou K, Wilson PA, et al., 2017, Strategies for in vivo screening and mitigation of hepatotoxicity associated with antisense drugs, Molecular Therapy - Nucleic Acids, Vol: 8, Pages: 383-394, ISSN: 2162-2531
Antisense oligonucleotide (ASO) gapmers downregulate gene expression by inducing enzyme-dependent degradation of targeted RNA and represent a promising therapeutic platform for addressing previously undruggable genes. Unfortunately, their therapeutic application, particularly that of the more potent chemistries (e.g., locked-nucleic-acid-containing gapmers), has been hampered by their frequent hepatoxicity, which could be driven by hybridization-mediated interactions. An early de-risking of this liability is a crucial component of developing safe, ASO-based drugs. To rank ASOs based on their effect on the liver, we have developed an acute screen in the mouse that can be applied early in the drug development cycle. A single-dose (3-day) screen with streamlined endpoints (i.e., plasma transaminase levels and liver weights) was observed to be predictive of ASO hepatotoxicity ranking established based on a repeat-dose (15 day) study. Furthermore, to study the underlying mechanisms of liver toxicity, we applied transcriptome profiling and pathway analyses and show that adverse in vivo liver phenotypes correlate with the number of potent, hybridization-mediated off-target effects (OTEs). We propose that a combination of in silico OTE predictions, streamlined in vivo hepatotoxicity screening, and a transcriptome-wide selectivity screen is a valid approach to identifying and progressing safer compounds.
Cohen SM, Fukushima S, Gooderham NJ, et al., 2016, Safety evaluation of substituted thiophenes used as flavoring ingredients., Food and Chemical Toxicology, Vol: 99, Pages: 40-59, ISSN: 1873-6351
This publication is the second in a series by the Expert Panel of the Flavor and Extract Manufacturers Association summarizing the conclusions of its third systematic re-evaluation of the safety of flavorings previously considered to be generally recognized as safe (GRAS) under conditions of intended use. Re-evaluation of GRAS status for flavorings is based on updated considerations of exposure, structural analogy, metabolism, pharmacokinetics and toxicology and includes a comprehensive review of the scientific information on the flavorings and structurally related substances. Of the 12 substituted thiophenes reviewed here, 11 were reaffirmed as GRAS based on their rapid absorption, metabolism and excretion in humans and animals; the low estimated dietary exposure from flavor use; the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels; and the lack of significant genotoxic and mutagenic potential. For one of the substituted thiophenes, 3-acetyl-2,5-dimethylthiophene, it was concluded that more detailed exposure information, comparative metabolism studies and comprehensive toxicity data, including an in-depth evaluation of the mechanism of action for any adverse effects observed, are required for continuation of its FEMA GRAS™ status. In the absence of these data, the compound was removed from the FEMA GRAS list.
Akingbasote JA, Foster AJ, Jones HB, et al., 2016, Improved hepatic physiology in hepatic cytochrome P450 reductase null (HRN™) mice dosed orally with fenclozic acid, Toxicology Research, Vol: 6, Pages: 81-88, ISSN: 2045-4538
Hepatic NADPH-cytochrome P450 oxidoreductase null (HRN™) mice exhibit no functional expression of hepatic cytochrome P450 (P450) when compared to wild type (WT) mice, but have normal hepatic and extrahepatic expression of other biotransformation enzymes. We have assessed the utility of HRN™ mice for investigation of the role of metabolic bioactivation in liver toxicity caused by the nonsteroidal anti-inflammatory drug (NSAID) fenclozic acid. In vitro studies revealed significant NADPH-dependent (i.e. P450-mediated) covalent binding of [14C]-fenclozic acid to liver microsomes from WT mice and HRN™ mice, whereas no in vitro covalent binding was observed in the presence of the UDP-glucuronyltransferase cofactor UDPGA. Oral fenclozic acid administration did not alter the liver histopathology or elevate the plasma liver enzyme activities of WT mice, or affect their hepatic miRNA contents. Livers from HRN™ mice exhibited abnormal liver histopathology (enhanced lipid accumulation, bile duct proliferation, hepatocellular degeneration, necrosis, inflammatory cell infiltration) and plasma clinical chemistry (elevated alanine aminotransferase, glutamate dehydrogenase and alkaline phosphatase activities). Modest apparent improvements in these abnormalities were observed when HRN™ mice dosed orally with fenclozic acid for 7 days at 100 mg/kg/day. Previously we observed more marked effects on liver histopathology and integrity in HRN™ mice dosed orally with the NSAID diclofenac for 7 days at 30 mg/kg/day. We conclude that HRN™ mice are valuable for assessing P450-related hepatic drug biotransformation, but not for drug toxicity studies due to underlying liver dysfunction. Nonetheless, HRN™ mice may provide novel insights into the role of inflammation in liver injury, thereby aiding its treatment.
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