Removal of 1,2-benzanthracene via the intercalation of 1,2-benzanthracene with DNA and magnetic bead-based separation.

In this study, DNA-functionalize-magnetic beads were investigated as sorbent materials for effective removing 1,2-benzanthracene (BaA) from water. In order to reveal the removal mechanism, the interaction mode between BaA and DNA was evaluated by using various characterization tools such as UV-visible and circular dichroism spectroscopy, fluorescence and resonance scattering spectroscopy, and agarose gel electrophoresis. In the presence of BaA, the melting temperature of DNA increased from 76.2 °C to 82.3 °C, which closely related to the intercalating of BaA. It was found that a part of the ethidium bromide (EB) binding sites to DNA were occupied by BaA in EB competing study. The results indicated that a new complex appeared between hsDNA and BaA, and the number of the binding sites (n) and the binding constants (KA) at different temperatures were obtained. DNA binding saturation value (≈0.80) was obtained by resonance scattering spectra study. BaA could be enriched and removed by DNA-functionalize-magnetic beads via the intercalation, and the removal efficiency was 97.73% when the initial concentration was 2.45 x10-6 mol·L-1 (559.31 µg/L).

DNA reactivity of altertoxin II: Identification of two covalent guanine adducts formed under cell-free conditions.

Fungi of the genus Alternaria infest many agricultural crops and produce numerous mycotoxins, of which altertoxin II (ATX II) is one of the most mutagenic metabolites. ATX II carries an epoxide group but the formation of DNA adducts has not been demonstrated to date. We report now that ATX II gives rise to two covalent adducts with guanine when incubated with DNA under cell-free conditions. These adducts were demonstrated by LC-high resolution MS after enzymatic degradation of the incubated DNA to deoxynucleosides. The major adduct results from the covalent binding of ATX II, presumably through the epoxide group, to guanine, whereas the minor guanine adduct is derived from the major one by the elimination of two equivalents of water. In addition, a third adduct was detected, formed through covalent binding of ATX II to cytosine followed by the loss of two equivalents of water. The direct DNA reactivity of ATX II may explain its high mutagenicity.

Occurrence of 3-nitrobenzanthrone and other powerful mutagenic polycyclic aromatic compounds in living organisms: polychaetes.

In this work we report the occurrence of powerful mutagenic 3-nitrobenzanthrone (3-NBA), in addition to 18 polycyclic aromatic hydrocarbons (PAHs), 6 oxygenated PAHs and 27 nitrated PAHs in polychaete worms. Benzanthrone (BA), another important mutagenic polycyclic aromatic compound (PAC) also was detected in the samples. Polychaete annelids have great ecological relevance, being widely distributed in different environmental conditions, from intertidal zones up to seven thousand feet deep areas. They are abundantly found in both contaminated and uncontaminated areas and, therefore, used as indicators of the pollution status of a given area. As we know, so far, most of these PACs has not been previously reported in living organisms before. The 3-NBA concentrations determined in this study were within 0.11-5.18 µg g-1. Other relevant PACs such as PAHs, quinones and nitro-PAHs were found in maximum concentrations at 0.013 µg g-1 (coronene) to 11.1 µg g-1 (benzo[k]fluoranthene), 0.823 µg g-1 (9,10-phenenthrenequinone) to 12.1 µg g-1 (1,4-benzoquinone) and 0.434 (1-nitronaphthalene) µg g-1 to 19.2 µg g-1 (6-nitrobenzo[a]pyrene), respectively. Principal component analysis (PCA), ternary correlations and diagnostic ratios were employed in order to propose probable sources for PACs. Although statistical analysis preliminarily has indicated both pyrogenic and petrogenic contributions, petrogenic sources were predominant reflecting the impacts of petroleum exploration and intensive traffic of boats in the study area.

Bioavailability, metabolism, and excretion of a complex Alternaria culture extract versus altertoxin II: a comparative study in rats.

Despite the frequent infection of agricultural crops by Alternaria spp., their toxic secondary metabolites and potential food contaminants lack comprehensive metabolic characterization. In this study, we investigated their bioavailability, metabolism, and excretion in vivo. A complex Alternaria culture extract (50 mg/kg body weight) containing 11 known toxins and the isolated lead toxin altertoxin II (0.7 mg/kg body weight) were administered per gavage to groups of 14 Sprague Dawley rats each. After 3 h and 24 h, plasma, urine and feces were collected to determine toxin recoveries. For reliable quantitation, an LC-MS/MS method for the simultaneous detection of 20 Alternaria toxins and metabolites was developed and optimized for either biological matrix. The obtained results demonstrated efficient excretion of alternariol (AOH) and its monomethyl ether (AME) via feces (> 89%) and urine (> 2.6%) after 24 h, while the majority of tenuazonic acid was recovered in urine (20 and 87% after 3 and 24 h, respectively). Moreover, modified forms of AOH and AME were identified in urine and fecal samples confirming both, mammalian phase-I (4-hydroxy-AOH) and phase-II (sulfates) biotransformation in vivo. Despite the comparably high doses, perylene quinones were recovered only at very low levels (altertoxin I, alterperylenol, < 0.06% in urine and plasma, < 5% in feces) or not at all (highly genotoxic, epoxide-holding altertoxin II, stemphyltoxin III). Interestingly, altertoxin I was detected in all matrices of rats receiving altertoxin II and suggests enzymatic de-epoxidation in vivo. In conclusion, the present study contributes valuable information to advance our understanding of the emerging Alternaria mycotoxins and their relevance on food safety.

High-resolution turbulent flow chromatography.

The resolution power of turbulent flow chromatography using carbon dioxide as the mobile phase and coated (crosslinked methyl phenyl polysiloxane) open tube columns (OTCs) as the stationary phase was investigated under retentive conditions (0

Polycyclic aromatic hydrocarbons in teas using QuEChERS and HPLC-FLD.

Polycyclic aromatic hydrocarbons (PAHs) are food-processing contaminants considered to be carcinogenic and genotoxic. Due to its drying process stage, teas may be contaminated with PAHs. The aim of the study was to validate an analytical method involving QuEChERS and HPLC-FLD for the determination of PAH4 in teas and evaluate the contamination levels in 10 different types of teas from Brazil. Recoveries varied from 54% to 99% and relative standard deviations from 1% to 21%. Limits of detection and quantification were from 0.03 to 0.3 µg/kg and 0.1 to 0.5 µg/kg, respectively. Mate tea presented the highest PAH levels, with PAH4 varying from 194 to 1795 µg/kg; followed by black (1.8-186 µg/kg), white (24-119 µg/kg), and green teas (3.1-92 µg/kg). Teas with lowest PAH4 were strawberry, lemongrass, peppermint, and boldo. Only trace levels of PAHs were detected in tea infusions, so apparently it would not affect PAH intake by Brazilian population.

Delphinidin protects colon carcinoma cells against the genotoxic effects of the mycotoxin altertoxin II.

Alternaria spp. are ubiquitous molds that are able to produce toxic secondary metabolites which may contaminate food globally. One of those is the mycotoxin altertoxin II (ATX-II), a genotoxic and mutagenic compound. In recent years, different flavonoids that may co-occur with mycotoxins in food were demonstrated to temper toxic effects of molds, mostly through their anti-oxidant properties. Thus, in this study, we assessed the influence of the berry anthocyanidin delphinidin on the toxicity of ATX-II in HT-29 colon carcinoma cells. We performed coupled SRB/WST-1 cytotoxicity assays which revealed only weak antagonistic interactions, and single-cell gel electrophoresis ("comet") assays, where we observed a potent protective effect of delphinidin on the DNA-damaging properties of ATX-II. Furthermore, we investigated the mechanism for this interaction. In the DCF assay delphinidin was found to reduce intracellular oxidative stress levels, which might contribute partly to the latter protection. However, LC-MS experiments showed that co-incubation of the mycotoxin with either delphinidin or its potential degradation product phloroglucinol aldehyde significantly decreased ATX-II concentrations in aqueous solutions, indicating that a direct chemical reaction of ATX-II with these components is likely responsible for the observed loss of toxicity. Our results indicate that delphinidin - and possibly other anthocyanins as well - might play a role in the protection of the gut from Alternaria-induced genotoxicity.

Optimisation of extraction methods and quantification of benzo[a]pyrene and benz[a]anthracene in yerba maté tea by isotope dilution mass spectrometry.

A gas chromatography-isotope dilution mass spectrometry (GC-IDMS) technique was developed for the quantification of two heavy polyaromatic hydrocarbons (PAHs), benz[a]anthracene and benzo[a]pyrene, in yerba maté tea (maté). The optimisation of two extraction methods, namely liquid-liquid extraction and accelerated solvent extraction, was carried out. Both optimised methods were validated using a certified reference material of fine dust and the results were within the expanded uncertainties at 95% confidence level. Recoveries of 99.2-106.7% with RSD of measurements of 1.1-2.3% were achieved for benz[a]anthracene. Recoveries of 95.7-101.9% with RSD of measurements of 0.4-1.4% were achieved for benzo[a]pyrene. The validated methods were applied for the extraction of benz[a]anthracene and benzo[a]pyrene in maté powder from NIST. A metrological approach was undertaken to ensure the traceability of measurement results. The uncertainties associated with the results were rigorously evaluated and also reported herein. Graphical abstract Quantification of benz[a]anthracene and benzo[a]pyrene using IDMS.

Potent Selective Inhibition of Monoamine Oxidase A by Alternariol Monomethyl Ether Isolated from Alternaria brassicae.

Alternariol monomethyl ether (AME), a dibenzopyrone derivative, was isolated from Alternaria brassicae along with altertoxin II (ATX-II). The compounds were tested for the inhibitory activity of monoamine oxidase (MAO), which catalyzes neurotransmitting monoamines. AME was found to be a highly potent and selective inhibitor of human MAO-A with an IC50 value of 1.71 µM; however, it was found to be ineffective for MAO-B inhibition. ATX-II was not effective for the inhibition of either MAO-A or MAO-B. The inhibition of MAO-A using AME was apparently instantaneous. MAO-A activity was almost completely recovered after the dilution of the inhibited enzyme with an excess amount of AME, suggesting AME is a reversible inhibitor. AME showed mixed inhibition for MAO-A in Lineweaver-Burk plots with a Ki value of 0.34 µM. The findings of this study suggest that microbial metabolites and dibenzopyrone could be potent MAO inhibitors. In addition, AME could be a useful lead compound for developing reversible MAO-A inhibitors to treat depression, Parkinson's disease, and Alzheimer's disease.

Two new antioxidant actinosporin analogues from the calcium alginate beads culture of sponge-associated Actinokineospora sp. strain EG49.

Marine sponge-associated actinomycetes represent an exciting new resource for the identification of new and novel natural products . Previously, we have reported the isolation and structural elucidation of actinosporins A (1) and B (2) from Actinokineospora sp. strain EG49 isolated from the marine sponge Spheciospongia vagabunda. Herein, by employing different fermentation conditions on the same microorganism, we report on the isolation and antioxidant activity of structurally related metabolites, actinosporins C (3) and D (4). The antioxidant potential of actinosporins C and D was demonstrated using the ferric reducing antioxidant power (FRAP) assay. Additionally, at 1.25 µM, actinosporins C and D showed a significant antioxidant and protective capacity from the genomic damage induced by hydrogen peroxide in the human promyelocytic (HL-60) cell line.

Altertoxins with potent anti-HIV activity from Alternaria tenuissima QUE1Se, a fungal endophyte of Quercus emoryi.

Screening of a small library of natural product extracts derived from endophytic fungi of the Sonoran desert plants in a cell-based anti-HIV assay involving T-cells infected with the HIV-1 virus identified the EtOAc extract of a fermentation broth of Alternaria tenuissima QUE1Se inhabiting the stem tissue of Quercus emoryi as a promising candidate for further investigation. Bioactivity-guided fractionation of this extract led to the isolation and identification of two new metabolites, altertoxins V (1) and VI (2) together with the known compounds, altertoxins I (3), II (4), and III (5). The structures of 1 and 2 were determined by detailed spectroscopic analysis and those of 3-5 were established by comparison with reported data. When tested in our cell-based assay at concentrations insignificantly toxic to T-cells, altertoxins V (1), I (3), II (4), and III (5) completely inhibited replication of the HIV-1 virus at concentrations of 0.50, 2.20, 0.30, and 1.50 µM, respectively. Our findings suggest that the epoxyperylene structural scaffold in altertoxins may be manipulated to produce potent anti-HIV therapeutics.

Effect-directed analysis of Elizabeth River porewater: developmental toxicity in zebrafish (Danio rerio).

In the present study, effect-directed analysis was used to identify teratogenic compounds in porewater collected from a Superfund site along the Elizabeth River estuary (VA, USA). Zebrafish (Danio rerio) exposed to the porewater displayed acute developmental toxicity and cardiac teratogenesis, presumably because of elevated sediment levels of polycyclic aromatic hydrocarbons (PAHs) from historical creosote use. Pretreatment of porewater with several physical and chemical particle removal methods revealed that colloid-bound chemicals constituted the bulk of the observed toxicity. Size-exclusive chromatography and normal-phase high-performance liquid chromatography were used to fractionate Elizabeth River porewater. Acute toxicity of porewater extracts and extract fractions was assessed as the pericardial area in embryonic zebrafish. The most toxic fraction contained several known aryl hydrocarbon receptor (AhR) agonists (e.g., 1,2-benzofluorene and 1,2-benzanthracene) and cytochrome P450 A1 (CPY1A) inhibitors (e.g., dibenzothiophene and fluoranthene). The second most toxic fraction contained known AhR agonists (e.g., benzo[a]pyrene and indeno[1,2,3-cd]pyrene). Addition of a CYP1A inhibitor, fluoranthene, increased toxicity in all active porewater fractions, suggesting synergism between several contaminants present in porewaters. The results indicate that the observed acute toxicity associated with Elizabeth River porewater results from high concentrations of AhR agonistic PAHs and mixture effects related to interactions between compounds co-occurring at the Elizabeth River site. However, even after extensive fractionation and chemical characterization, it remains plausible that some active compounds in Elizabeth River porewater remain unidentified.

A new compound from an endophytic fungus Alternaria tenuissima.

A new secondary metabolite, named altertoxin IV (1), together with altertoxin II (2), was isolated from the fermentation broth of Alternaria tenuissima, an endophytic fungal strain residing in the stem of Tribulus terrestris L. The structure of new compound 1 was established by HR-ESI-MS, multinuclear NMR spectroscopy, and single crystal X-ray diffraction method. In their in vitro bioassay, compound 2 exhibited moderate cytotoxic activity against PC-3 cell lines with an IC50 value of 14.28 µM.

Dereplication strategies for targeted isolation of new antitrypanosomal actinosporins A and B from a marine sponge associated-Actinokineospora sp. EG49.

High resolution Fourier transform mass spectrometry (HRFTMS) and nuclear magnetic resonance (NMR) spectroscopy were employed as complementary metabolomic tools to dereplicate the chemical profile of the new and antitrypanosomally active sponge-associated bacterium Actinokineospora sp. EG49 extract. Principal Component (PCA), hierarchical clustering (HCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) were used to evaluate the HRFTMS and NMR data of crude extracts from four different fermentation approaches. Statistical analysis identified the best culture one-strain-many-compounds (OSMAC) condition and extraction procedure, which was used for the isolation of novel bioactive metabolites. As a result, two new O-glycosylated angucyclines, named actinosporins A (1) and B (2), were isolated from the broth culture of Actinokineospora sp. strain EG49, which was cultivated from the Red Sea sponge Spheciospongia vagabunda. The structures of actinosporins A and B were determined by 1D- and 2D-NMR techniques, as well as high resolution tandem mass spectrometry. Testing for antiparasitic properties showed that actinosporin A exhibited activity against Trypanosoma brucei brucei with an IC50 value of 15 µM; however no activity was detected against Leishmania major and Plasmodium falciparum, therefore suggesting its selectivity against the parasite Trypanosoma brucei brucei; the causative agent of sleeping sickness.

Warkmycin, a novel angucycline antibiotic produced by Streptomyces sp. Acta 2930*.

A novel angucycline-type antibiotic, warkmycin, was isolated from the culture filtrate of Streptomyces strain Acta 2930. Its chemical structure was elucidated by HR-MS, one-dimensional and 2D NMR experiments. The compound inhibits the growth of Gram-positive bacteria and shows a strong antiproliferative activity against mouse fibroblast cell line NIH-3T3 and human cancer cell lines HepG2 and HT29.

Saccharosporones A, B and C, cytotoxic antimalarial angucyclinones from Saccharopolyspora sp. BCC 21906.

Three new angucyclinones, saccharosporones A, B and C, together with (+)-ochromycinone, (+)-rubiginone B2, tetrangulol methyl ether and fujianmycin A, were obtained from fermentation of the terrestrial actinomycete of the genus Saccharopolyspora BCC 21906 isolated from a soil collected in Chanthaburi Province, Thailand. Structures of the new compounds and their relative configurations were assigned by NMR spectral data interpretation. Saccharosporones A and B exhibited antimalarial activity against Plasmodium falciparum K1 with IC50 values of 4.1 and 3.9 µM. Both metabolites also possessed cytotoxic activities against cancer cell lines (KB, MCF-7 and NCI-H187) and nonmalignant Vero cell, while saccharosporone C only showed cytotoxic activity against NCI-H187.

Search method for inhibitors of Staphyloxanthin production by methicillin-resistant Staphylococcus aureus.

Staphyloxanthin, a yellow pigment produced by methicillin-resistant Staphylococcus aureus (MRSA), is a virulent factor escaping from the host immune system. A new screening method for inhibitors of staphyloxanthin production by MRSA was established using paper disks. By this screening method, inhibitors of staphyloxanthin production were selected from the natural product library (ca. 300) and from actinomycete culture broths (ca. 1000). From the natural product library, four known inhibitors of lipid metabolism, cerulenin, dihydrobisvertinol, xanthohumol and zaragozic acid, were found to inhibit staphyloxanthin production; however, typical antibiotics used clinically, including vancomycin, had no effect on staphyloxanthin production. From actinomycete culture broths, two known anthraquinones, 6-deoxy-8-O-methylrabelomycin and tetrangomycin, were found to inhibit staphyloxanthin production by MRSA in the paper disk assay. These results suggested that this screening method is useful and effective to find compounds targeting staphyloxanthin production, leading to a new type of chemotherapeutics against MRSA infection.

Mayamycin, a cytotoxic polyketide from a Streptomyces strain isolated from the marine sponge Halichondria panicea.

A new benz[a]anthracene derivative called mayamycin (1) was identified in cultures of Streptomyces sp. strain HB202, which was isolated from the marine sponge Halichondria panicea and selected because of its profound antibiotic activity. The ability to produce aromatic polyketides was indicated by genetic analyses, demonstrating the presence of a type II polyketide synthase. The production of mayamycin (1) was induced by variation of the culture conditions. The structure of 1 was elucidated by HPLC-UV/MS and NMR spectroscopy. Mayamycin (1) exhibited potent cytotoxic activity against eight human cancer cell lines and showed activity against several bacteria including antibiotic-resistant strains.

Fractionation of polycyclic aromatic hydrocarbon residues in soils.

Understanding the forms and availabilities of polycylic aromatic hydrocarbons (PAHs) would have considerable benefits for their risk assessment, and is of crucial importance for food security and remediation strategies in contaminated sites. In this work, the forms of six PAHs (fluorene, phenanthrene, fluoranthene, pyrene, benzo[a]anthracene, and benzo[a]pyrene) in soils were separated into three fractions including a desorbing fraction, a non-desorbing fraction, and a bound residual fraction using a sequential extraction mass balance approach. The desorbing and non-desorbing fractions were extracted with hydroxypropyl-beta-cyclodextrin (HPCD) and dichloromethane:acetone (1:1, vol/vol), respectively. The desorbing and non-desorbing fractions always dominated the total PAH content in soils. The proportion of bound PAH residue in nonsterilized soils was small (<16%), and even smaller (4.5%) in sterilized soils. The concentrations of the desorbing fraction of PAHs as well as the percentage of this fraction to the total PAH content in soils clearly decreased in 0-16 weeks, which may be due to microbial biodegradation and its transfer to other fractions in soils. The concentrations of the non-desorbing PAH fractions increased in sterilized soils, while remaining nearly constant or decreasing to some extent in nonsterilized soils after 16 weeks. The proportion of non-desorbing PAH fractions significantly increased in 16 week-incubation, and this proportion was positively correlated with the molecular weights of the PAHs tested, indicating that larger PAHs are more likely to be present in non-desorbing fractions. The bound PAH residue tended to increase at first and decrease thereafter over the 0-16-week period, and microbes played an important role in the formation of bound residue.