Carcinogenic Metabolites Research Articles

Dual-signal electrochemical aptasensor involving hybridization chain reaction amplification for aflatoxin B1 detection

Since aflatoxin B1 (AFB1) is a highly toxic and carcinogenic secondary metabolite, it is of great importance to develop an effective method for detection of it. Based on hybridization chain reaction (HCR), we proposed a ratiometric dual-signal electrochemical aptasensor (DECA) to realize rapid and sensitive detection of AFB1. In the aptasensor, ferrocene (Fc) and methylene blue (MB)-tagged single-stranded DNA sequences acted as dual-signal sources. Based on this, more stable hairpin DNA (HS-H1) and MB-labeled auxiliary hairpin DNA (H1 and H2) were introduced to extend the sensing platform. In presence of AFB1, it will compete with MB-cDNA and specifically combine with Fc-labeled aptamer. As a result, MB-cDNA will release and trigger the HCR for MB signal amplification with an enhancement in sensitivity. Besides, the ratio of current variations behaved a ratiometric signal output mode. In the proof-of-concept study, the single-signal mode behaved a linear range of 1 pM~10 nM with limit of detection (LOD) of 0.56 pM (IMB) and 0.15 pM (IFc), respectively, while the ratiometric detection mode showed the lowest LOD of 0.12 pM (S/N = 3). The good specificity, reproducibility, and stability of DECA further revealed its promising application in food safety monitoring.

CYP2S1 and CYP2W1 expression is associated with patient survival in breast cancer.

The cytochrome P450 family of enzymes metabolise a wide range of compounds and play important roles in breast cancer pathogenesis due to their involvement in estrogen metabolism and the production of carcinogenic metabolites during this process. The orphan CYPs, CYP2S1, and CYP2W1 are reportedly upregulated in breast cancer. However, their expression and association with clinicopathological and survival parameters have not been previously assessed in a large cohort of breast cancers. Protein expression of CYP2S1 and CYP2W1 was assessed in early‐stage invasive breast cancers (n = 1,426) using immunohistochemistry and correlated with various clinicopathological parameters and survival. mRNA expression of CYP2S1 and CYP2W1 was also assessed in the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) cohort. Low nuclear and cytoplasmic CYP2S1 was significantly associated with high‐grade tumours (p ≤ 0.009), intermediate Nottingham prognostic index (NPI) group (p ≤ 0.025), high mitotic frequency (p ≤ 0.002), human epidermal growth factor receptor 2 (HER2)‐negative disease (p ≤ 0.011), and ductal carcinoma (p ≤ 0.022). Cytoplasmic CYP2S1 was additionally associated with patients ≥50 years (p < 0.001), estrogen receptor (ER)‐positive tumours (p = 0.011), and high nuclear pleomorphism (p = 0.003). Low cytoplasmic CYP2W1 was significantly associated with patients ≥50 years (p = 0.002), HER2‐negative disease (p = 0.003), intermediate NPI (p = 0.013), and mitosis (p = 0.009). Low cytoplasmic CYP2S1 was significantly associated with adverse breast cancer specific survival (p = 0.034), which remained so in multivariate analysis (hazard ratio [HR]: 0.639; 95% confidence interval [CI]: 0.483–0.846; p = 0.002). Low nuclear CYP2W1 was significantly associated with adverse breast cancer specific survival (p = 0.012), with significance also maintained in multivariate analysis (HR: 0.677; 95% CI: 0.510–0.898; p = 0.007). No associations with survival were observed in the METABRIC cohort. CYP2S1 and CYP2W1 are associated with patient survival in breast cancer and may be important prognostic biomarkers.

Estetrol, a Natural Estrogen with Selective Tissue activity (NEST)

ABSTRACT Introduction Current contraceptives can pose an increased risk of venous thromboembolism and breast cancer due to their pharmacological profile. Estetrol (E4) is a native estrogen produced by the human fetus during pregnancy, which has a pharmacological profile different from that of other estrogens. Objective Additional studies were conducted to better characterize the unique pharmacological and pharmacokinetic profile of E4. Methods E4 has been characterized in nonclinical studies, investigated in clinical trials as a component of contraceptives and is being evaluated for treatment of menopausal symptoms. Results E4 is quickly absorbed after oral administration and does not exhibit an extensive binding to plasma proteins in contrast to other estrogens. It has a half-life of at least 24h. It is transformed into inactive sulfo- and glucurono-conjugates, primarily excreted in urine. No potentially carcinogenic metabolites have been identified after E4 metabolization. E4 does not significantly affect CYP450 liver enzymes and has minimal impact on hemostatic parameters, plasma levels of lipids and glucose. In cell, human and animal studies, E4 has limited effects on normal and malignant breast tissue. At the cellular level, E4 like other estrogens, binds and activates the nuclear estrogen receptor α (ERα) and recruits the same coregulators, while selective estrogen receptor modulators (SERMs) recruit other coregulators. However, unlike the other estrogens, E4 induces very limited activity on membrane ERα and antagonizes this pathway in the presence of estradiol, thereby uniquely uncoupling nuclear and membrane activation. Conclusions Based on its unique structure, pharmacokinetic/dynamic properties and distinctive mode-of-action, E4 is considered a Natural Estrogen with Selective Tissues activity (NEST), with a favorable benefit-to-risk ratio. Disclosure Yes, this is sponsored by industry/sponsor: Estetra SRL (an affiliate company of Mithra Pharmaceuticals, Belgium; Publication support by Mayne Pharma Clarification Industry initiated, executed and funded study Any of the authors act as a consultant, employee or shareholder of an industry for: Estetra SRL (an affiliate company of Mithra Pharmaceuticals, Belgium; Publication support by Mayne Pharma

Blue mold rot caused by Penicillium expansum on Polygonatum odoratum var. pluriflorum.

Polygonatum odoratum var. pluriflorum, called "Dunggulle", is cultivated in East Asia to obtain rhizomes. In Korea and China, these rhizomes are used in traditional teas, health beverages, and herbal medicines (Zhao and Li, 2015). In 2019, Dunggulle was cultivated in 47 hectares, with an annual output of 120M/T in Korea. In November 2020, Dunggulle rhizomes with symptoms of blue mold rot were observed at a Dunggulle farm storage (36°06'01''N, 127°29'20''E) in Geuman, Korea, where the temperature ranged from 9 to 13°C, with an average humidity of 70%. The disease incidence was 2 to 3% out of 200 rhizomes across all markets surveyed. The disease begins with a greenish blue mold covering the rhizome surface (30 to 60%), followed by rhizome rot with a dark brown color as the disease progresses. Leading edges of the rotten rhizome pieces were sterilized with 1% NaOCl and 70% ethanol and placed on MEA (Malt Extract Agar) with penicillin G and streptomycin (both 50 µg/mL). After 7 days of incubation at 25°C, greenish-blue colonies appeared, from which a monospore was isolated. A representative isolated strain was deposited in the Korean Agricultural Culture Collection (KACC, Wanju, Korea) with Acc. No. KACC 49832. The strain grew slowly on MEA at 25°C (8 to 18 mm diam. after 7 days), producing greenish blue conidia. The conidiophores were hyaline and mostly terverticillate; the branches were appressed against the main axis; the stipes were smooth-walled; and the metulae were cylindrical, 10 to 13 × 2.7 to 3.2 µm, with 6 to 10 flask-shaped phialides, measured 9 to 12 × 2.7 to 3.1 µm. The conidia were globose or subglobose and 2.8 to 4.1 µm diam. These morphological characteristics fit well with the description of Penicillium expansum (Frisvad & Samson, 2004). Genomic DNA was extracted from the mycelia of the KACC 49832 MEA plate. ITS rDNA, beta-tubulin (BenA), and calmodulin (CaM) gene regions were sequenced for identification (Houbraken et al., 2020), and the rsulting sequences were deposited in GenBank (Acc. Nos. MZ189258, MZ226688, and MZ226689, respectively). Comparison with the GenBank sequences revealed that the Korean isolate was highly similar to P. expansum (ITS rDNA 99.8%, BenA 98.6%, and CaM 97.8%). Phylogenetic results based on the maximum-likelihood analysis revealed that KACC 49832 was grouped with P. expansum. To demonstrate pathogenicity, 10 µL of conidial suspension (1.3 × 105 conidia/mL) was dropped on the surface of three Dunggulle rhizomes scratched with a syringe needle. For the control, sterile water was applied on three control rhizomes. All rhizomes were surface-sterilized as referred above before being sprayed and dried. All inoculated and control rhizomes were kept in incubator at 25°C and 90-95% relative humidity. After a week, the inoculated points showed symptoms similar to those of the initial infection, whereas controls remained symptomless. The re-isolated fungus matched KACC 49832 based on morphological and sequence analyses, thereby fulfilling Koch's postulates. The experiment was performed three times. To our knowledge, this is the first report of P. expansum as a Dunggulle rhizome pathogen in Korea. As this pathogen is known to produce patulin, a carcinogenic fungal metabolite, further studies on the mycotoxicity of the infected rhizomes are required. This report might help manage the storage conditions of Dunggulle rhizomes to prevent the blue mold rot.

LKB1 phosphorylation and deactivation in lung cancer by NNAL, a metabolite of tobacco-specific carcinogen, in an isomer-dependent manner.

LKB1 loss of function is one key oncogenic event in lung cancer. Clinical data suggest that LKB1 loss of function is associated with patients' smoking status. The responsible ingredients and molecular mechanisms in tobacco for LKB1 loss of function, however, are not defined. In this study, we reported that NNAL, a major metabolite of a tobacco-specific carcinogen NNK, induces LKB1 phosphorylation and its loss of function via the β-AR/PKA signaling pathway in an isomer-dependent manner in human lung cancer cells. NNAL exposure also resulted in enhanced lung cancer cell migration and chemoresistance in an LKB1-dependent manner. A 120-day NNAL exposure in lung cancer cells, mimicking its chronic exposure among smokers, resulted in more prominent LKB1 phosphorylation, cell migration, and chemoresistance even in the absence of NNAL, indicating the long-lasting LKB1 loss of function although such an effect eventually disappeared after NNAL was removed for two months. These observations were confirmed in a lung cancer xenograft model. More importantly, human lung cancer tissues revealed elevated LKB1 phosphorylation in comparison to the paired normal lung tissues. These results suggest that LKB1 loss of function in human lung cancer could be extended to its phosphorylation, which may be mediated by NNAL from tobacco smoke in an isomer-dependent manner via the β-AR/PKA signaling pathway.

Immunological imbalance, gene polymorphism of biotransformation enzymes, and steroid hormone receptors in tumors in breast cancer patients

It is well known that results of breast cancer (BC) hormonal therapy depend on expression of tumor estradiol and progesterone receptors (ER and PR) in tumor tissue. Mechanisms of ER+/PR+ tumors conversion to ER+/PR- and ER-/PR- tumors remain scarcely studied. The decrease of steroid receptors expression seems to depend on action of genotoxic metabolites of environmental carcinogens (particularly, benzo[a]pyrene, BP) and endogenous steroids (in particular, estradiol, E2). The formation of these metabolites is regulated by the biotransformation enzymes. On the other hand, the formation of DNA-adducts with genotoxic metabolites may induce the synthesis of specific antibodies. Previously, it was shown that increase of the serum IgA-antibodies levels against Bp and E2 over the levels of IgA-antibodies against progesterone (IgA-Bp/IgA-Pg &gt; 1 and IgA-E2/IgA-Pg), could be interpreted as immunological imbalance associated with high BC risk in healthy women. The purpose of this study was to detect the suggested associations between ER+/PR+ tumors conversion to ER+/PR+ and ER-/PR- tumors and immunological imbalance in the BC patients with distinct gene variants of biotransformation enzymes: CYP1A1*2A (rs 4646903), CYP1B1 (rs1056836), CYP19A1 (rs2470152), GSTT1 (del), GSTP1 (rs1695). The IgA-Bp, IgA-E2 and IgA-Pg were studied in 1321 non-smoking BC patients by non-competitive solid phase immunoassay. The conjugates of Bp, E2 and Pg with bovine serum albumin were adsorbed as target antibodies. The goat antibodies against human IgA conjugated with horseradish peroxidase were used for detection of the studied specific antibodies. Gene polymorphisms of biotransformation enzymes were analyzed by the real-time PCR. Tumor ER and PR were detected by the standard immunohistochemical methods.ER+/PR+ tumors in BC patients at the stage I (N = 534) were found in 68.7%, ER+/PR- in 15.6%, ER-/ PR- in 15.7%. In BC patients at the II-IV stage (N = 787), frequency of ER+/PR+ tumors decreased to 60.2%, ER+/PR- was similar (15.8%), and ER-/PR- increased to 24.0% (p &lt; 0.0001). These alterations were revealed in BC patients at the IgA-Bp/IgA-Pg ratios &gt; 1, and IgA-E2/IgA-Pg &gt; 1 only. There were no differences found between BC patients at stage I and II-IV at the ER+/PR+, ER+/PR-, ER-/PR- frequencies when these ratios were low.The frequency of ER+/PR+ tumors in homozygotes TT of CYP19A1 was 77.1% at the I stage and 60.1% at the II-IV stages. Respectively the frequencies of ER-/PR- tumors were 11.8% and 26.1% (p &lt; 0.001). ER+/ PR+ tumors were revealed in GSTT1 “+” BC patients at the I stage in 68.7% and at the II-IV stages in 58.0%. Respectively ER-/PR- tumors were found in 16.6% and 24.5% (p &lt; 0.0004). The frequency of ER+/PR+ tumors was 57.1% in homozygotes GG of GSTP1 at the I stage and 60.7% at the II-IV stages. Respectively the frequencies of ER+/PR- were 14.3% and 22.2% and ER-/PR- were 28.6% and 19.0% (p &lt; 0.001). Proportions of low and high IgA-Bp/IgA-Pg and IgA-E2/IgA-Pg ratios were the same at the any enzyme genotype of studied CYP or GST variants. In conclusion, we have revealed a sufficient contribution of immunological imbalance to the conversion of steroid receptors in breast cancer growth, being independent of several CYP and GST gene polymorphisms.

Effects of Turmeric Powder on Aflatoxin M1 and Aflatoxicol Excretion in Milk from Dairy Cows Exposed to Aflatoxin B1 at the EU Maximum Tolerable Levels.

Due to the climatic change, an increase in aflatoxin B1 (AFB1) maize contamination has been reported in Europe. As an alternative to mineral binders, natural phytogenic compounds are increasingly used to counteract the negative effects of AFB1 in farm animals. In cows, even low dietary AFB1 concentrations may result in the milk excretion of the genotoxic carcinogen metabolite aflatoxin M1 (AFM1). In this study, we tested the ability of dietary turmeric powder (TP), an extract from Curcuma longa (CL) rich in curcumin and curcuminoids, in reducing AFM1 mammary excretion in Holstein–Friesian cows. Both active principles are reported to inhibit AFM1 hepatic synthesis and interact with drug transporters involved in AFB1 absorption and excretion. A crossover design was applied to two groups of cows (n = 4 each) with a 4-day washout. Animals received a diet contaminated with low AFB1 levels (5 ± 1 µg/kg) for 10 days ± TP supplementation (20 g/head/day). TP treatment had no impact on milk yield, milk composition or somatic cell count. Despite a tendency toward a lower average AFM1 milk content in the last four days of the treatment (below EU limits), no statistically significant differences with the AFB1 group occurred. Since the bioavailability of TP active principles may be a major issue, further investigations with different CL preparations are warranted.

The regulatory role of the Aspergillus flavus core retromer complex in aflatoxin metabolism

Aflatoxins are a series of highly toxic and carcinogenic secondary metabolites that are synthesized by Aspergillus species. The degradation of aflatoxin enzymes is an important regulatory mechanism which modulates mycotoxin producing. The retromer complex is responsible for the retrograde transport of specific biomolecules and the vacuolar fusion in the intracellular transport. Late endosomal-associated GTPase (Rab7) has been shown to be a downstream effector protein of the retromer complex. A deficiency in the retromer complex or Rab7 results in several cellular trafficking problems in yeast and humans, like protein abnormal accumulation. However, whether retromer dysfunction is involved in aflatoxin synthesis remains unclear. Here, we report that the core retromer complex, which comprises three vacuolar protein sorting-associated proteins (AflVps26-AflVps29-AflVps35), is essential for the development of dormant and resistant fungal forms such as conidia (asexual reproductive spore) and sclerotia (hardened fungal mycelium), as well as aflatoxin production and pathogenicity, in Aspergillus flavus. In particular, we show the AflVps26-AflVps29-AflVps35 complex is negatively correlated with aflatoxin exportation. Structural simulation, site-specific mutagenesis, and coimmunoprecipitation experiments showed that interactions among AflVps26, AflVps29, and AflVps35 played crucial roles in the retromer complex executing its core functions. We further found an intrinsic connection between AflRab7 and the retromer involved in vesicle-vacuole fusion, which in turn affected the accumulation of aflatoxin synthesis-associated enzymes, suggesting that they work together to regulate the production of toxins. Overall, these results provide mechanistic insights that contribute to our understanding of the regulatory role of the core retromer complex in aflatoxin metabolism.

Efficient Prevention of Aspergillus flavus Spores Spread in Air Using Plasmonic Ag-AgCl/α-Fe2O3 under Visible Light Irradiation.

Aspergillus flavus is a kind of widespread fungi that can produce carcinogenic, teratogenic, and mutagenic secondary metabolites known as aflatoxins. Aspergillus flavus mainly spread through the means of fungal spores in air, thus preventing the spores spread is an effective strategy to control aflatoxins contamination from source. Herein, a rapid and efficient control way to prevent the spread of Aspergillus flavus spores in air was demonstrated. Ag-AgCl nanoparticles were combined with tetrahedral α-Fe2O3 to form plasmonic composites that presented 93.65 ± 1.53% prevention rate of Aspergillus flavus spores under 50 min visible light irradiation. The efficient activity was attributed to the synergy effect of Ag including intrinsic disinfection, electron sink, and localized surface plasmon resonance effect, which were proven by photoelectric characterization, density functional theory, and finite difference time domain methods. The calculated work functions of α-Fe2O3, Ag, and AgCl were 3.71, 4.52, and 5.38 eV, respectively, which could accelerate photoinduced carrier transfer through Ag during photoreaction. Moreover, it was found that the intrinsic disinfection of Ag and hydroxyl radical from photocatalytic reaction were the main factors to the prevention of Aspergillus flavus spores, which resulted in the destruction of spore structure and the leakage of intracellular protein with 62.15 ± 2.63 μg mL-1. Most important, it was proven that the composites also showed high activity (90.52 ± 1.26%) to prevent Aspergillus flavus spore spread in the storage process of peanuts. These findings not only provided useful information for an efficient and potential strategy to prevent Aspergillus flavus contamination but also could be as a reference in toxic fungi control.

Benzo[a]pyrene-Environmental Occurrence, Human Exposure, and Mechanisms of Toxicity.

Benzo[a]pyrene (B[a]P) is the main representative of polycyclic aromatic hydrocarbons (PAHs), and has been repeatedly found in the air, surface water, soil, and sediments. It is present in cigarette smoke as well as in food products, especially when smoked and grilled. Human exposure to B[a]P is therefore common. Research shows growing evidence concerning toxic effects induced by this substance. This xenobiotic is metabolized by cytochrome P450 (CYP P450) to carcinogenic metabolite: 7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), which creates DNA adducts, causing mutations and malignant transformations. Moreover, B[a]P is epigenotoxic, neurotoxic, and teratogenic, and exhibits pro-oxidative potential and causes impairment of animals’ fertility. CYP P450 is strongly involved in B[a]P metabolism, and it is simultaneously expressed as a result of the association of B[a]P with aromatic hydrocarbon receptor (AhR), playing an essential role in the cancerogenic potential of various xenobiotics. In turn, polymorphism of CYP P450 genes determines the sensitivity of the organism to B[a]P. It was also observed that B[a]P facilitates the multiplication of viruses, which may be an additional problem with the widespread COVID-19 pandemic. Based on publications mainly from 2017 to 2022, this paper presents the occurrence of B[a]P in various environmental compartments and human surroundings, shows the exposure of humans to this substance, and describes the mechanisms of its toxicity.

Metagenomic analysis of the fecal microbiome in patients with colorectal cancer compared to healthy controls as a function of age.

3532 Background: Colorectal cancer (CRC) incidence is increasing in young patients ( &lt; 50 years old) without a clear etiology. Emerging data has implicated the fecal microbiome in CRC carcinogenesis. However, its impact on young onset CRC (YO-CRC) is poorly defined. Colibactin producing E. Coli and fadA producing Fusobacterium nucleatum can drive CRC carcinogenesis, however their effects across the age spectrum are unknown. Methods: We performed a meta-analysis of fecal metagenomics sequencing from n = 692 patients with CRC and n = 602 healthy controls from eleven studies to evaluate species and known microbial derived factors (colibactin and FadA) associated with CRC as a function of age. Generalized linear mixed effects regression was used to model the predicted prevalence of gene families and taxa as a non-linear function of age. Two-stage individual patient data meta-analysis (IPDMA) with adjustment for gender, CRC status, and body mass index was also used to estimate summary odds ratios for colibactin, F. nucleatum, and E. Coli. Interaction ORs were obtained to assess the difference in the effect of each gene or taxa on CRC case status in YO-CRC. Shannon Diversity index and metabolic pathway differences in the fecal metagenome for YO-CRC patients were assessed using phyloseq and MetaCyc respectively using an IPDMA approach. Results: Summary odds ratios (OR) for CRC were increased relative to controls with the presence of colibactin (OR 1.92 95%CI 1.08-3.38), fadA (OR 4.57 95%CI 1.63-12.85), and F. nucleatum (OR 6.93 95%CI 3.01-15.96) in models of all patients adjusted for age, gender, and body mass index. The OR for CRC for the presence of E.coli was 2.02 (0.92-4.45). An increase in the prevalence of F. nucleatum (OR = 1.40 [1.18; 1.65] and Escherichia coli (OR = 1.14 [1.02; 1.28]) per 10-year increase in age was observed in models including samples from both CRC and healthy controls. No difference was observed for Shannon Diversity (OR 1.36 95%CI 0.68-2.72) or MetaCyc pathways in YO-CRC patients. Species relative abundance was differentially enriched in YO-CRC relative to old CRC patients and controls for five species- Intestinimonas butyriciproducens, Holdemania filiformis, Firimicutues bacterium CAG 83, Bilophilia wadsworthia, and Alistipes putredinis. Conclusions: Strong associations with CRC status were observed for colibactin, fadA, and F. nucleatum with increased F. nucleatum in older patients. Several species were enriched in YO-CRC patients including B. wadsworthia which can produce carcinogenic sulfur metabolites and is increased with adherence to a sulfur microbial diet-low in vegetables and legumes. A sulfur microbial diet has also been associated with higher incidence of YO-CRC in population studies (Nguyen Gastroenterology 2021). Additional study is warranted to understand causal mechanisms of enriched species observed in YO-CRC patients.

Protective effects of methanolic leaf extracts of Monanthotaxis caffra against aflatoxin B1-induced hepatotoxicity in rats.

Aflatoxins are potent hepatotoxic and carcinogenic secondary metabolites produced by toxigenic fungi. The present study investigated the protective effect of methanolic leaf extracts of Monanthotaxis caffra (MLEMC) against aflatoxin B1-induced toxicity in male Sprague-Dawley rats. The rats were randomly divided into 6 groups of 8 animals each. Five groups were administered orally for seven days with three different concentrations of MLEMC (100 mg/kg, 200 mg/kg and 300 mg/kg), curcumin (10 mg/kg) or vehicle (25% propylene glycol). The following day, these groups were administered 1 mg/kg b.w. of aflatoxin B1 (AFB1). The experiment was terminated three days after administration of AFB1. Group 6 represented untreated healthy control. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, creatinine and liver histopathology were evaluated. Methanolic leaf extracts of M. caffra decreased the levels of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase and creatinine in the sera of rats as compared with the AFB1 intoxicated group. Co-administration of MLEMC improved the histological characteristics of the hepatocytes in contrast to the AFB1 treated group, which had mild to severe hepatocellular injuries including bile duct proliferation, bile duct hyperplasia, lymphoplasmacytic infiltrate and fibrosis. Extracts of M. caffra were beneficial in mitigating the hepatotoxic effects of AFB1 in rats by reducing the levels of liver enzymes and preventing hepatic injury.

In vitro detoxification of aflatoxin B1 by aqueous extracts of medicinal herbs

Aflatoxin contamination in food commodities is a major food safety concern all over the world. These aflatoxins are a group of carcinogenic secondary metabolites produced by some fungi belonging to Aspergillus section Flavi. To minimize the level of aflatoxins in food commodities, a wide range of pre- and post-harvest procedures have been employed. In this study, aqueous extracts of 13 medicinal herbs were assessed for their ability to detoxify aflatoxin B1 (AFB1), the most potent and commonly occurring carcinogen in foods. Among them, herbal extracts of Hybanthus enneaspermus, Eclipta prostrata and Centella asiatica exhibited over 70% detoxification of AFB1. The degradation of AFB1 upon treatment with these herbal extracts was confirmed by liquid chromatography–mass spectrometry analysis. Two fractions (R f 0.75 and 0.87) purified from H. enneaspermus by using thin-layer chromatography displayed in vitro AFB1-detoxifying properties. Gas chromatography–mass spectrometry analysis of the active fractions revealed the presence of linalool and bornyl acetate as the major components suggesting possible involvement of volatile compounds of H. enneaspermus in the detoxification of AFB1. To our knowledge, this is the first report on the detoxification of AFB1 by H. enneaspermus, E. prostrata and C. asiatica aqueous extracts.

Role of Porphyromonas gingivalis in oral and orodigestive squamous cell carcinoma.

Oral and esophageal squamous cell carcinomas harbor a diverse microbiome that differs compositionally from precancerous and healthy tissues. Though causality is yet to be definitively established, emerging trends implicate periodontal pathogens such as Porphyromonas gingivalis as associated with the cancerous state. Moreover, infection with P.gingivalis correlates with a poor prognosis, and P.gingivalis is oncopathogenic in animal models. Mechanistically, properties of P.gingivalis that have been established in vitro and could promote tumor development include induction of a dysbiotic inflammatory microenvironment, inhibition of apoptosis, increased cell proliferation, enhanced angiogenesis, activation of epithelial-to-mesenchymal transition, and production of carcinogenic metabolites. The microbial community context is also relevant to oncopathogenicity, and consortia of P.gingivalis and Fusobacterium nucleatum are synergistically pathogenic in oral cancer models in vivo. In contrast, oral streptococci, such as Streptococcus gordonii, can antagonize protumorigenic epithelial cell phenotypes induced by P.gingivalis, indicating functionally specialized roles for bacteria in oncogenic communities. Consistent with the notion of the bacterial community constituting the etiologic unit, metatranscriptomic data indicate that functional, rather than compositional, properties of the tumor-associated communities have more relevance to cancer development. A consistent association of P.gingivalis with oral and orodigestive carcinoma could have diagnostic potential for early detection of these conditions that have a high incidence and low survival rates.

The Association of Microbiome Dysbiosis With Colorectal Cancer

Many studies have been conducted to identify the causative organisms in colorectal cancer (CRC) and compare the microbiota of healthy individuals and those with CRC. The pathways by which the microbiota promotes CRC development are not yet fully understood. The hypothesized mechanisms include damage to the DNA, production of carcinogenic metabolites, and promotion of chronic inflammation. In a state of dysbiosis, the gut loses protective bacteria and is enriched with pathogenic and cancer-promoting bacteria, which promotes functions associated with cancer such as angiogenesis, loss of apoptosis, and cell proliferation. We have established a strong link between microbiota dysbiosis and certain species of bacteria and even viruses involved in tumorigenesis. In this review, we look at some of the major identified species and how they are related to CRC. Future research should include and even focus on mycobiome and virome on CRC development. Due to the diversity of the gut microbiome, there is a high possibility that the gain and loss of bacteria and their metabolic functions lead to CRC.

Inhibition of gut microbial β-glucuronidase effectively prevents carcinogen-induced microbial dysbiosis and intestinal tumorigenesis

The bidirectional interaction between carcinogens and gut microbiota that contributes to colorectal cancer is complicated. Reactivation of carcinogen metabolites by microbial β-glucuronidase (βG) in the gut potentially plays an important role in colorectal carcinogenesis. We assessed the chemoprotective effects and associated changes in gut microbiota induced by pre-administration of bacterial-specific βG inhibitor TCH-3511 in carcinogen azoxymethane (AOM)-treated APCMin/+ mice. AOM induced intestinal βG activity, which was reflected in increases in the incidence, formation, and number of tumors in the intestine. Notably, inhibition of gut microbial βG by TCH-3511 significantly reduced AOM-induced intestinal βG activity, decreased the number of polyps in both the small and large intestine to a frequency that was similar in mice without AOM exposure. AOM also led to lower diversity and altered composition in the gut microbiota with a significant increase in mucin-degrading Akkermansia genus. Conversely, mice treated with TCH-3511 and AOM exhibited a more similar gut microbiota structure as mice without AOM administration. Importantly, TCH-3511 treatment significant decreased Akkermansia genus and produced a concomitant increase in short-chain fatty acid butyrate-producing gut commensal microbes Lachnoospiraceae NK4A136 group genus in AOM-treated mice. Taken together, our results reveal a key role of gut microbial βG in promoting AOM-induced gut microbial dysbiosis and intestinal tumorigenesis, indicating the chemoprotective benefit of gut microbial βG inhibition against carcinogens via maintaining the gut microbiota balance and preventing cancer-associated gut microbial dysbiosis. Thus, the bacterial-specific βG inhibitor TCH-3511 is a potential chemoprevention agent for colorectal cancer.

Rapid and Quantitative Analysis of Aflatoxin M1 From Milk Using Atmospheric Pressure-Matrix Assisted Laser Desorption/Ionization (AP-MALDI)-Triple Quadrupole Selected Reaction Monitoring.

Aflatoxin M1 (AFM1) is a carcinogenic hydroxylated metabolite commonly found in milk. It is relatively stable toward decontamination procedures posing a major health risk, and it requires an international regulatory mandate of detection at trace levels. To develop a high-throughput, reliable, and compliant method for the identification of AFM1 in milk samples using atmospheric pressure-matrix assisted laser desorption/ionization (AP-MALDI) selected reaction monitoring (SRM) quantitation. The milk sample was diluted in water and cleaned with immunoaffinity chromatography (IAC), followed by analysis using AP-MALDI hyphenated with a triple quadrupole mass spectrometer for SRM. A fast and reliable AP-MALDI SRM quantitative method was developed for the determination of AFM1 with analysis time of 1 min per sample. The diagnostic product ions of AFM1 at 273.1 u and 229.2 u were monitored during the SRM. The calibration curves yielded excellent linearity (R2 = 0.99) with good recoveries for quality control samples (97-106%). The ion ratios of the qualifier to quantifier displayed excellent RSD (1-7.8%) for n = 3. The developed method provided rapid quantification for AFM1. The fast AP-MALDI SRM method can allow analysis of AFM1 in a large number of milk samples. Given the time required for analysis, cost-effectiveness, and superior analytical performance, this method can be adopted in commercial food testing laboratories. Aflatoxins (AF) are a major health risk. Speedy analysis of large sample sizes from food is a risk mitigation strategy but remains an unmet need. Quantitative, chromatography-free, and internal standard-free AP-MALDI SRM based analysis of AF is a high-throughput and cost-efficient alternative. Satisfactory performance was achieved for quantitative AP-MALDI SRM analysis of AFM1 in milk subsequent to a simple sample clean-up step.

Early expression of the aflatoxin gene cluster in Aspergillus nomiae isolated from Brazil nut

Aspergillus nomiae is the most important contaminant in Brazil nut due to its high incidence in these nuts and its strong production of carcinogenic metabolites: aflatoxins (AF). Aflatoxin biosynthesis pathway in A. nomiae is poorly studied. Thus, in present investigation, aflatoxin production and gene cluster (aflC, aflQ, aflU, and aflX) expression profile were evaluated on two strains of A. nomiae isolated from Brazil nut samples collected in the Amazon region, and cultivated on Brazil nut-based medium. The results showed that the expression of the aflatoxin gene cluster in A. nomiae, started at day 2 and occurred before the production of aflatoxins. Aflatoxin production (AFB1 and AFG1) was detected on day 3 on both strains. From day 4 onwards, all four toxins were detected and their production kept at similar proportions (AFG1>AFB1>AFG2>AFB2). Thus, the anticipated information obtained through early expression profile results of aflC, aflQ, aflU, and aflX gene cluster in A. nomiae may foresee aflatoxin production before its detection in Brazil nuts.

The prevalence of aflatoxins in different nut samples: A global systematic review and probabilistic risk assessment

&lt;abstract&gt; &lt;p&gt;Aflatoxins are secondary carcinogenic fungal metabolites derived from the toxic various Aspergillus species. These fungi can easily infect nuts and grains. A global systematic review was done to extract data on the concentration of aflatoxins in different nuts. Besides, risk assessment was conducted on data. The scientific databases were searched systematically from 2000 to 2020. Based on the results, aflatoxin B1 (AFB1) had the most frequency in nut samples. The mean concentration of aflatoxin total (AFT) and AFB1 in nuts were as follows: peanut (37.85, 32.82 μg/kg), pistachio (31.42, 39.44 μg/kg), almond (3.54, 3.93 μg/kg), walnut (42.27, 22.23 μg/kg), hazelnut (17.33, 10.54 μg/kg), Brazil nut (4.61, 3.35 μg/kg), and other nuts (26.22, 7.38 μg/kg). According to country the margin of exposure (MOE) value for adult was as Argentina (21) &amp;gt; Congo (67) &amp;gt; India (117) &amp;gt; Bangladesh (175) &amp;gt; Cameroon (238) &amp;gt; Iran (357) &amp;gt; Bahrain (438) &amp;gt; Brazil (447) &amp;gt; Ghana (606) &amp;gt; South Africa (1017) &amp;gt; Egypt (1176) &amp;gt; USA (1505) &amp;gt; China (1526) &amp;gt; Cyprus (1588). The MOE of the consumers in some countries was considerably below the safety margin of 10,000. To conclude, nuts are highly consumed by different consumers, so it is necessary to emphasize strict control measures to prevent contamination of these foods with aflatoxins.&lt;/p&gt; &lt;/abstract&gt;

Nuclear Magnetic Resonance Approach in Brazil Nut Oil and the Occurrence of Aflatoxins.

Carcinogenic metabolites of fungi such as aflatoxins play a toxic role in some tree nuts and need to be monitored in their by-products, such as oil. In this context, Brazil nut (Bertholletia excelsa) oil, which is a commodity of great economic importance to Brazil, requires attention to monitor the presence of these toxic agents. Therefore, this study aimed to evaluate the presence of aflatoxins in Brazil nut oil and relate it to the presence of fatty acids in the oil as a surveillance tool for food safety. Brazil nut oil samples (n= 25) were acquired in northern Brazil as (a) non-branded products (n= 07) produced by local farmers using artisanal methods from nuts to be discarded by the industry and (b) industrialized products (n= 18). The samples were analyzed for total aflatoxin content by high-performance liquid chromatography and fatty acid content by nuclear magnetic resonance imaging. Seven (28%) samples were positive for the aflatoxin fractions (B1 + B2 + G1 + G2), ranging from undetected (<2.32) to 50.87 μg/kg. Of the aflatoxin positive samples evaluated by NMR analysis, it was not possible to state that the presence of a particular fatty acid can interfere or influence aflatoxin contamination. This was the first study with data on aflatoxin occurrence in Brazil nut oil. Nevertheless, further research is required to relate saturated or unsaturated fatty acid content with aflatoxin levels. We also suggest the implementation of systems to prevent contamination of the raw materials (seed) and detoxification of the oil to guarantee the product's safety and quality.