The in vitro anticancer activity of the crude extract of the sponge-associated fungus Eurotium cristatum and its secondary metabolites

Two new Aspera chaetominines A and B, and a new derivative of terrein, isolated from marine sponge associated fungus Aspergillus versicolour SCSIO XWS04 F52

Two new alkaloids, Aspera chaetominines A (1) and B (2), a new derivative (3) of terrein, and together with 11 known compounds (4-14) were isolated from marine sponge Callyspongia sp. -derived fungus Aspergillus versicolour SCSIO XWS04 F52, which was identified on the basis of morphology and ITS sequence analysis. The planar structures of 1-3 were determined by spectroscopic (1H, 13C NMR, HSQC, HMBC, and 1H-1H COSY), and MS analysis. Compounds 1 and 2 showed cytotoxic activity against leukaemia K562 and colon cancer cells SW1116 with IC50 7.5 to 12.5 μM, and also compounds 1 and 2 exhibited significant protection against H1N1 virus-induced cytopathogenicity in MDCK cells with IC50 values of 15.5 and 24.5 μM, respectively.

Anthraquinones and Their Analogues from Marine-Derived Fungi: Chemistry and Biological Activities

Anthraquinones are an interesting chemical class of polyketides since they not only exhibit a myriad of biological activities but also contribute to managing ecological roles. In this review article, we provide a current knowledge on the anthraquinoids reported from marine-derived fungi, isolated from various resources in both shallow waters such as mangrove plants and sediments of the mangrove habitat, coral reef, algae, sponges, and deep sea. This review also tentatively categorizes anthraquinone metabolites from the simplest to the most complicated scaffolds such as conjugated xanthone–anthraquinone derivatives and bianthraquinones, which have been isolated from marine-derived fungi, especially from the genera Apergillus, Penicillium, Eurotium, Altenaria, Fusarium, Stemphylium, Trichoderma, Acremonium, and other fungal strains. The present review, covering a range from 2000 to 2021, was elaborated through a comprehensive literature search using the following databases: ACS publications, Elsevier, Taylor and Francis, Wiley Online Library, MDPI, Springer, and Thieme. Thereupon, we have summarized and categorized 296 anthraquinones and their derivatives, some of which showed a variety of biological properties such as enzyme inhibition, antibacterial, antifungal, antiviral, antitubercular (against Mycobacterium tuberculosis), cytotoxic, anti-inflammatory, antifouling, and antioxidant activities. In addition, proposed biogenetic pathways of some anthraquinone derivatives are also discussed.

A nonadride derivative from the marine-derived fungus Aspergillus chevalieri PSU-AMF79

One new nonadride enantiomer, ent-epiheveadride, along with five known dioxopiperazine derivatives were isolated from the marine-derived fungus Aspergillus chevalieri PSU-AMF79. Their structures were identified by extensive spectroscopic analysis. The absolute configuration of ent-epiheveadride was determined by comparison of the specific rotation and electronic circular dichroism data with those of related known compounds. It exhibited antifungal activity against Cryptococcus neoformans ATCC90113 flucytosine-resistant and Candida albicans NCPF3153 with the MIC values of 128 and 200 µg/mL, respectively. In addition, the known L-alanyl-L-tryptophan anhydride displayed TMEM16A inhibitory activity with 65.0% inhibition at a concentration of 5 µg/mL.

Physcion and Physcion 8-O-β-D-glucopyranoside: Natural Anthraquinones with Potential Anticancer Activities

Nature has provided prodigious reservoirs of pharmacologically active compounds for drug development since times. Physcion and physcion 8-O-β-D-glucopyranoside (PG) are bioactive natural anthraquinones which exert anti-inflammatory and anticancer properties with minimum or no adverse effects. Moreover, physcion also exhibits anti-microbial and hepatoprotective properties, while PG is known to have anti-sepsis as well as ameliorative activities against dementia. This review aims to highlight the natural sources and anticancer activities of physcion and PG, along with associated mechanisms of actions. On the basis of the literature, physcion and PG regulate multitudinous cell signaling pathways through the modulation of various regulators of cell cycle, protein kinases, microRNAs, transcriptional factors, and apoptosis linked proteins resulting in the effective killing of cancerous cells in vitro as well as in vivo. Both compounds effectively suppress metastasis, furthermore, physcion acts as an inhibitor of 6PGD and also plays an important role in chemosensitization. This review article suggests that physcion and PG are potent anticancer drug candidates, but further investigations on their mechanism of action and pre-clinical trials are mandatory in order to comprehend the full potential of these natural cancer killers in anticancer remedies.

Endophytic fungus, Chaetomium globosum, associated with marine green alga, a new source of Chrysin

The marine ecosystem is an extraordinary reserve of pharmaceutically important, bioactive compounds even in this “synthetic age”. Marine algae-associated endophytic fungi have gained prominence as an important source of bioactive compounds. This study was conducted on secondary metabolites of Chaetomium globosum-associated with marine green alga Chaetomorpha media from the Konkan coastline, India. Its ethyl acetate extract (CGEE) exhibited an IC₅₀ value of 7.9 ± 0.1 µg/mL on MCF-7 cells. CGEE exhibited G2M phase cell cycle arrest, ROS production and MMP loss in MCF-7 cells. The myco-components in CGEE contributing to the cytotoxicity were found by Gas Chromatography/Mass Spectrometry analyses. Chrysin, a dihydroxyflavone was one of the forty-six myco-components which is commonly found in honey, propolis and passionflower extracts. The compound was isolated and characterized as fungal chrysin using HPLC, UV–Vis spectroscopy, LC–MS, IR and NMR analyses by comparing with standard chrysin. The purified compound exhibited an IC₅₀ value of 49.0 ± 0.6 µM while that of standard chrysin was 48.5 ± 1.6 µM in MCF-7 cells. It induced apoptosis, G1 phase cell cycle arrest, MMP loss, and ROS production. This is the first report of chrysin from an alternative source with opportunities for yield enhancement.

Purification, characterization, and hypoglycemic properties of eurocristatine from Eurotium cristatum spores in Fuzhuan brick tea

Fuzhuan brick tea (FBT) is a Chinese dark tea that is famous for its significant health benefits, in which Eurotium cristatum (E. cristatum) strains play a vital role in its postfermentation process. In this study, eurocristatine with hypoglycemic activity was discovered for the first time and purified from the spores of E. cristatum growing in FBT. Eurocristatine (98%) was obtained by D-101 macroporous resin-based column chromatography and preparative high performance liquid chromatography (HPLC) with a C18 column as the stationary phase and 35% acetonitrile in ultrapure water as the mobile phase. Hypoglycemic activity in a Hep-G2 cell hypoglycemic model was used as a screening indicator during purification. The chemical structure of eurocristatine was characterized by ESI/MS, 1H NMR and 13C NMR analyses. The antidiabetic effects of eurocristatine were verified in high-fat diet/streptozocin-induced type 2 diabetes mellitus (T2DM) rats. The results showed that eurocristatine significantly reduced fasting blood glucose. Our study demonstrated that eurocristatine, as a newly discovered hypoglycemic active substance, could be considered a potential candidate for the treatment of diabetes and its complications.

Fungi as a Potential Source of Pigments: Harnessing Filamentous Fungi

The growing concern over the harmful effects of synthetic colorants on both the consumer and the environment has raised a strong interest in natural coloring alternatives. As a result the worldwide demand for colorants of natural origin is rapidly increasing in the food, cosmetic and textile sectors. Natural colorants have the capacity to be used for a variety of industrial applications, for instance, as dyes for textile and non-textile substrates such as leather, paper, within paints and coatings, in cosmetics, and in food additives. Currently, pigments and colorants produced through plants and microbes are the primary source exploited by modern industries. Among the other non-conventional sources, filamentous fungi particularly ascomycetous and basidiomycetous fungi (mushrooms), and lichens (symbiotic association of a fungus with a green alga or cyanobacterium) are known to produce an extraordinary range of colors including several chemical classes of pigments such as melanins, azaphilones, flavins, phenazines, and quinines. This review seeks to emphasize the opportunity afforded by pigments naturally found in fungi as a viable green alternative to current sources. This review presents a comprehensive discussion on the capacity of fungal resources such as endophytes, halophytes, and fungi obtained from a range or sources such as soil, sediments, mangroves, and marine environments. A key driver of the interest in fungi as a source of pigments stems from environmental factors and discussion here will extend on the advancement of greener extraction techniques used for the extraction of intracellular and extracellular pigments. The search for compounds of interest requires a multidisciplinary approach and techniques such as metabolomics, metabolic engineering and biotechnological approaches that have potential to deal with various challenges faced by pigment industry.

Recycling of Chinese herb residues by endophytic and probiotic fungus Aspergillus cristatus CB10002 for the production of medicinal valuable anthraquinones

Background

The global prevalence of traditional Chinese medicine stimulates the prosperous development of herb medicines, but the annual generation of massive herb residues becomes big issues about environmental pollution and waste of resources. Microbes play important roles in the circulation of substances in nature, and endophytes represent an underexplored microbial resource possessing the unique symbiotic relationship with plants, not only for discovery of secondary metabolites, but also for potential green recycling of herb residues.

Results

The recycling capacities of several endophytic strains were respectively evaluated via solid state fermentation with herb residues of commercial Huazhenghuisheng oral-liquid (HOL). Among them, Aspergillus cristatus CB10002, a probiotic fungus isolated from Chinese Fu-brick tea, was competent to recycle HOL residues for the production of medicinal valuable anthraquinones, in which four of them, especially citreorosein with significant anti-obesity activity, were first discovered in A. cristatus. Subsequent quantitative analysis showed that about 2.0 mg/g citreorosein and 7.5 mg/g total anthraquinones could be obtained after 35-day fermentation, which was very competitive and economically beneficial. Further nutritional comparisons also revealed that the recycling process indeed ameliorated the nutrients of HOL residues, and thus proposed a possibility to directly dispose the final leftovers as a compost organic fertilizer.

Conclusions

The endophytic and probiotic fungus A. cristatus CB10002 isolated from Chinese Fu-brick tea was screened out to effectively reutilize HOL residues for the production of nine medicinal valuable anthraquinones, whose biosynthesis may be regulated by the induction of HOL residues. The competitive yields of these anthraquinones, as well as the certain composting properties of final leftovers, have made the microbial recycling of HOL residues economically beneficial. Our work demonstrated a promising applied potential of A. cristatus in reutilization of herb residues, and provided a practical strategy for sustainable and value-added microbial recycling of herb residues.

Electronic supplementary material

The online version of this article (10.1186/s12934-019-1150-9) contains supplementary material, which is available to authorized users.

Anti-inflammatory prenylbenzaldehyde derivatives isolated from Eurotium cristatum

Two undescribed prenylbenzaldehyde derivatives, cristaldehydes A and B, and an undescribed quinone derivative, cristaquinone A, along with seven known compounds were isolated from the fungus Eurotium cristatum. The structures of undescribed compounds were determined by spectroscopic analysis including NMR, HR-ESIMS, and single-crystal X-ray diffraction. This is the first report of identification of a dibenzannulated 6,6-spiroketal derivative, cristaldehyde B, in a natural product. Cytotoxic and anti-inflammatory activities of all compounds were evaluated. Cristaldehyde A and cristaquinone A along with five known compounds showed significant anti-inflammatory activities with IC₅₀ values in the range from 0.37 to 14.50 μM.

Induction of pigment production through media composition, abiotic and biotic factors in two filamentous fungi

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Pigment production and accumulation is dependent of high C:N ratios in F. oxysporum and A. chevaleri.

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Red pigment content of F. oxysporum in terms of Absorbance units per gram of biomass increased in 191% through use of blue light. Different light wavelengths stimulate synthesis of additional pigments in A. chevalieri with highest accumulation in red and UV-light.

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Stimulation of pigment production in co-culture is species – specific, being only accomplished in A. chevalieri. With a rise higher that 500% of a pigment obtained in green light.

In addition to plant-derived, fungal pigments have become an alternative in respect to synthetic ones. Besides Monascus sp., several pigment-producing fungi do not have culture conditions well-established yet. In this research, media composition, light wavelength and co-culture were evaluated, results were reported in Absorbance Units per gram of biomass (AU/Bgr). For Fusarium oxysporum a C:N ratio above 7 was advantageous, using both complex and defined media; blue LED light increased the AU/Bgr value from 18013 to 344; co-culture did not enhance pigment production. In Aspergillus chevalieri a high C:N ratio with glucose as carbon source was ideal. When exposing cultures to light, UV and red light gave the highest pigmentation; moreover, differential UV-VIS spectra in all wavelengths suggested production of additional pigments. Particularly a pigment observed when cultured in green light was also found in co-culture with yeast and there was an improvement of AU/Bgr value of 52549%. This is the first report regarding light effect and co-culture for these fungi, as well as C:N ratio for A. chevalieri.

Simultaneous degradation of β-cypermethrin and 3-phenoxybenzoic acid by Eurotium cristatum ET1, a novel "golden flower fungus" strain isolated from Fu Brick Tea

Beta-cypermethrin (β-CY) and its major metabolite 3-phenoxybenzoic acid (3-PBA) spread extensively in the environment because of utilization in agricultural and home formulations, exerting negative impact on environment as well as human health. Several golden flower fungi were isolated from fu brick tea, by which the biodegradation of β-CY and 3-PBA was evaluated, turning out strain Eurotium cristatum ET1 had the highest capacity. Furthermore, β-CY and 3-PBA degradation rates were positively correlated with biomass of E. cristatum ET1, and the processes of degradation fitted well with a first-order kinetic equation. The half-lives of β-CY and 3-PBA ranged from 3.382 to 11.517 days and 1.749 to 3.194 days, respectively, under different substrate concentrations, incubation temperatures, and pH values. The degraded products were analyzed using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, and results showed that E. cristatum ET1 degrades β-CY by transforming it into 3-PBA, which is then gradually metabolized into phenol and catechol. Moreover, E. cristatum ET1 showed efficiency in degrading these metabolites. Our results suggest that this strain is a potential microorganism for bioremediation of pesticide-contaminated environments and fermented foods.

Isolation and Synthesis of Misszrtine A: A Novel Indole Alkaloid From Marine Sponge-Associated Aspergillus sp. SCSIO XWS03F03

A novel indole alkaloid, misszrtine A (1), was isolated from marine sponge-derived fungus Aspergillus sp. SCSIO XWS03F03. The planar structure of 1 was assigned by analysis of spectroscopic data, the absolute configuration of which was unambiguously determined by total synthesis. Compound 1 represents the first example of N-isopentenyl tryptophan methyl ester with a phenylpropanoic amide arm, which exhibited a potent antagonistic activity on HL60 (IC₅₀ = 3.1 μM) and LNCaP (IC₅₀ = 4.9 μM) cell lines. Bioactivity evaluation reveals that functional group on indole nitrogen of 1 has a great effect on its cytotoxity, which provides a mean to probe the structure-activity relationships of 1.

Physcion induces apoptosis through triggering endoplasmic reticulum stress in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and aggressive malignancies. The current study aimed to investigate the effect of physcion, a major active ingredient in several traditional herbal medicinal plants, for the treatment of HCC. Our data showed that physcion markedly induced apoptosis in human HCC cell lines Huh7 and Bel7402. The pro-apoptotic role of physcion on HCC cells was mediated by mitochondria dysfunction, which was caused by activation of endoplasmic reticulum(ER) stress. Moreover, our findings revealed that physcion stimulated ER stress by activating AMPK signaling. Besides in HCC cell lines, the anti-cancer activity of physcion was also examined in a xenograft mice model, which showed that physcion could significantly suppressed tumor growth. In conclusion, our results indicated that physcion can be considered as a potential chemotherapeutic agent in the treatment of HCC.

Physcion blocks cell cycle and induces apoptosis in human B cell precursor acute lymphoblastic leukemia cells by downregulating HOXA5

Acute lymphoblastic leukemia (ALL) presents the most common type of malignancy in children and ranks the third most common cancer in adults. This study is aimed to investigate the anti-leukemia activity of physcion in ALL. Our results have showed that physcion could significantly suppress cell growth, induce apoptosis and blocked cell cycle progression in vitro. Mechanistically, we found that physcion downregulated the expression of HOXA5, which is responsible for the anti-leukemia activity of physcion. To verify this finding, siRNA targeting HOXA5 and overexpressing plasmid were used to repress HOXA5 expression and introduce ectopic overexpression of HOXA5 in ALL cell lines, respectively. Our results showed that overexpression of HOXA5 significantly abrogated the inducing effect of physcion on apoptosis and cell cycle blockasde. In contrast, knockdown of HOXA5 by siRNA enhanced the anti-tumor effect of physcion on ALL cell lines. Our results provided experimental base for the use of physcion in the treatment of ALL.

Polyphasic taxonomy of Aspergillus section Aspergillus (formerly Eurotium), and its occurrence in indoor environments and food

Aspergillus section Aspergillus (formerly the genus Eurotium) includes xerophilic species with uniseriate conidiophores, globose to subglobose vesicles, green conidia and yellow, thin walled eurotium-like ascomata with hyaline, lenticular ascospores. In the present study, a polyphasic approach using morphological characters, extrolites, physiological characters and phylogeny was applied to investigate the taxonomy of this section. Over 500 strains from various culture collections and new isolates obtained from indoor environments and a wide range of substrates all over the world were identified using calmodulin gene sequencing. Of these, 163 isolates were subjected to molecular phylogenetic analyses using sequences of ITS rDNA, partial β-tubulin (BenA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2) genes. Colony characteristics were documented on eight cultivation media, growth parameters at three incubation temperatures were recorded and micromorphology was examined using light microscopy as well as scanning electron microscopy to illustrate and characterize each species. Many specific extrolites were extracted and identified from cultures, including echinulins, epiheveadrides, auroglaucins and anthraquinone bisanthrons, and to be consistent in strains of nearly all species. Other extrolites are species-specific, and thus valuable for identification. Several extrolites show antioxidant effects, which may be nutritionally beneficial in food and beverages. Important mycotoxins in the strict sense, such as sterigmatocystin, aflatoxins, ochratoxins, citrinin were not detected despite previous reports on their production in this section. Adopting a polyphasic approach, 31 species are recognized, including nine new species. ITS is highly conserved in this section and does not distinguish species. All species can be differentiated using CaM or RPB2 sequences. For BenA, Aspergillus brunneus and A. niveoglaucus share identical sequences. Ascospores and conidia morphology, growth rates at different temperatures are most useful characters for phenotypic species identification.

Aspergchromones A and B, two new polyketides from the marine sponge-associated fungus Aspergillus sp. SCSIO XWS03F03

Two new polyketides, aspergchromones A (1) and B (2), together with five known compounds, secalonic acid D (3), noreugenin (4), (3S)-5-hydroxymellein (5), (4S)-6-hydroxyisosclerone (6), and (-)-regiolone (7), were isolated from the ethyl acetate extract of marine sponge-derived fungus Aspergillus sp. SCSIO XWS03F03. Their structures were elucidated by means of spectroscopic techniques (1D and 2D NMR, MS, UV, and IR). The absolute configurations of the new compounds were established by ECD calculations. Compound 3 showed moderate antimicrobial activity.

Anti-proliferative Effect of Physcion on Human Gastric Cell Line via Inducing ROS-Dependent Apoptosis

In this study, the anti-proliferative effect of physcion, an anthraquinone derivative isolated and characterized from both terrestrial and marine sources, against human gastric cancer SGC-7901 cells was investigated and the underlying mechanisms were explored. Physcion reduced SGC-7901 cell viability in a dose- and time-dependent manner, as demonstrated by MTT assay. It triggered the mitochondrial/caspase apoptotic pathway indicated by loss of mitochondrial membrane potential and cytochrome c release. Moreover, physcion induced a sustained activation of the phosphorylation of AMPK, and compound C (an inhibitor of AMPK) significantly reversed physcion-induced apoptosis in SGC-7901 cells. In addition, physcion provoked the generation of reactive oxygen species (ROS) in SGC-7901 cells, while the antioxidant N-acetyl cysteine almost completely blocked physcion-induced AMPK activation and apoptosis. Taken together, these findings suggest that physcion induces apoptosis through a ROS/AMPK-dependent mitochondrial pathway.

Physcion, a naturally occurring anthraquinone derivative, induces apoptosis and autophagy in human nasopharyngeal carcinoma

AIM

Physcion is a major bioactive ingredient in the traditional Chinese medicine Radix et Rhizoma Rhei, which has an anthraquinone chemical structure and exhibits a variety of pharmacological activities including laxative, hepatoprotective, anti-inflammatory, anti-microbial and anti-proliferative effects. In this study we investigated the effect of physcion on human nasopharyngeal carcinoma in vitro and in vivo, as well as the mechanisms underlying the anti-tumor action.

METHODS

The nasopharyngeal carcinoma cell line CNE2 was treated with physcion, and cell viability was detected using MTT and colony formation assays. Flow cytometry was used to assess the cell cycle arrest, mitochondrial membrane potential loss, apoptosis, autophagy and intracellular ROS generation. Apoptotic cell death was also confirmed by a TUNEL assay. The expression of target or marker molecules was determined using Western blotting. The activity of caspase-3, 8, and 9 was detected with an ELISA kit. A xenograft murine model was used to evaluate the in vivo anti-tumor action of physcion, the mice were administered physcion (10, 20 mg·kg-1·d-1, ip) for 30 d.

RESULTS

Treatment with physcion (5, 10, and 20 μmol/L) dose-dependently suppressed the cell viability and colony formation in CNE2 cells. Physcion (10 and 20 μmol/L) dose-dependently blocked cell cycle progression at G1 phase and induced both caspase-dependent apoptosis and autophagy in CNE2 cells. Furthermore, physcion treatment induced excessive ROS generation in CNE2 cells, and subsequently disrupted the miR-27a/ZBTB10 axis, resulting in repression of the transcription factor Sp1 that was involved in physcion-induced apoptosis and autophagy. Moreover, physcion-induced autophagy acted as a pro-apoptotic factor, and possibly contributed to physcion-induced apoptosis. In the xenograft murine model, administration of physcion dose-dependently suppressed the tumor growth without affecting the body weight. Furthermore, the anti-tumor effects of physcion were correlated with downregulation of Sp1 and suppression of miR-27a in the tumor tissues.

CONCLUSION

Physcion induces apoptosis and autophagy in human nasopharyngeal carcinoma by targeting Sp1, which was mediated by ROS/miR-27a/ZBTB10 signaling. The results suggest that physcion is a promising candidate for the treatment of human nasopharyngeal carcinoma.

Anthraquinones and Derivatives from Marine-Derived Fungi: Structural Diversity and Selected Biological Activities

Anthraquinones and their derivatives constitute a large group of quinoid compounds with about 700 molecules described. They are widespread in fungi and their chemical diversity and biological activities recently attracted attention of industries in such fields as pharmaceuticals, clothes dyeing, and food colorants. Their positive and/or negative effect(s) due to the 9,10-anthracenedione structure and its substituents are still not clearly understood and their potential roles or effects on human health are today strongly discussed among scientists. As marine microorganisms recently appeared as producers of an astonishing variety of structurally unique secondary metabolites, they may represent a promising resource for identifying new candidates for therapeutic drugs or daily additives. Within this review, we investigate the present knowledge about the anthraquinones and derivatives listed to date from marine-derived filamentous fungi's productions. This overview highlights the molecules which have been identified in microorganisms for the first time. The structures and colors of the anthraquinoid compounds come along with the known roles of some molecules in the life of the organisms. Some specific biological activities are also described. This may help to open doors towards innovative natural substances.

Physcion inhibits the metastatic potential of human colorectal cancer SW620 cells in vitro by suppressing the transcription factor SOX2

AIM

Physcion, an anthraquinone derivative, exhibits hepatoprotective, anti-inflammatory, anti-microbial and anti-cancer activities. In this study we examined whether and how physcion inhibited metastatic potential of human colorectal cancer cells in vitro.

METHODS

Human colorectal cancer cell line SW620 was tested. Cell migration and invasion were assessed using a wound healing and Transwell assay, respectively. The expression levels of transcription factor SOX2 in the cells were modulated with shRNA targeting SOX2 and SOX2 overexpressing plasmid. The expression of target molecules involved in epithelial-mesenchymal transition (EMT) process and the signaling pathways was determined with Western blots or qRT-PCR. ROS levels were measured using DCF-DA.

RESULTS

Physcion (2.5, 5 mol/L) did not affect the cell viability, but dose-dependently inhibited the cell adhesion, migration and invasion. Physcion also inhibited the EMT process in the cells, as evidenced by the increased epithelial marker E-cadherin expression, and by decreased expression of mesenchymal markers N-cadherin, vimentin, fibronectin and α-SMA, as well as transcriptional repressors Snail, Slug and Twist. Physcion suppressed the expression of SOX2, whereas overexpression of SOX2 abrogated the inhibition of physcion on metastatic behaviors. Physcion markedly increased ROS production and phosphorylation of AMPK and GSK3β in the cells, whereas the AMPK inhibitor compound C or the ROS inhibitor NAC abolished the inhibition of physcion on metastatic behaviors.

CONCLUSION

Physcion inhibits the metastatic potential of human colorectal cancer cells in vitro via activating ROS/AMPK/GSK3β signaling pathways and suppressing SOX2.

Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs

Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.

A new prenylated indole diketopiperazine alkaloid from Eurotium cristatum

A new prenylated indole diketopiperazine alkaloid, cristatumin F (1), and four known metabolites, echinulin (2), dehydroechinulin (3), neoechinulin A (4) and variecolorin O (5), were isolated from the crude extract of the fungus Eurotium cristatum. The structure of 1 was elucidated primarily by NMR and MS methods. The absolute configuration of 1 was assigned using Marfey’s method applied to its acid hydrolyzate. Cristatumin F (1) showed modest radical scavenging activity against DPPH radicals, and exhibited marginal attenuation of 3T3L1 pre-adipocytes.

Isolation, screening and partial purification of antimicrobial antibiotics from soil Streptomyces sp. SCA 7

Thirty-seven actinomycetes strains were isolated from soil samples collected from an agriculture field in Vengodu, Thiruvannamalai District, Tamil Nadu, India (latitude: 12° 54' 0033″, North; longitude: 79° 78' 5216″, East; elevation: 228.6/70.0 ft/m). The isolates were assessed for antagonistic activity against five Gram-positive bacteria, seven Gram-negative bacteria, and two pathogenic fungi. During the initial screening, 43% of the strains showed weak activity, 16% showed moderate activity, 5% showed good activity, and 35% showed no antagonistic activity. Among the strains tested, SCA 7 showed strong antimicrobial activity. Maximum biological activity was obtained on modified nutrient glucose agar (MNGA) medium. The mycelia of SCA 7 were extracted with methanol and tested against microbial pathogens using the disc diffusion method. The crude extract was purified partially using column chromatography and assessed for antimicrobial activity. Fraction 10 showed good activity against Staphylococcus epidermidis (31.25 μg/mL) and Malassezia pachydermatis (500 μg/mL) and the active principle (fraction 10) was identified as 2,4-bis (1,1-dimethylethyl) phenol. Based on morphological, physiological, biochemical, cultural, and molecular characteristics (16S rDNA sequencing), this strain was identified as Streptomyces sp. SCA 7. It could be used in the development of new substances for pharmaceutical or agricultural purposes.

Marine natural products

This review covers the literature published in 2012 for marine natural products, with 1035 citations (673 for the period January to December 2012) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1241 for 2012), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

Physcion from marine-derived fungus Microsporum sp. induces apoptosis in human cervical carcinoma HeLa cells

Recently, the relationship between apoptosis and cancer has been emphasized and the induction of apoptosis is recognized as one of the key mechanisms of anti-cancer agents. Marine-derived fungi are valuable sources of structurally diverse bioactive anticancer agents. In the present study, a marine-derived fungus, Microsporum sp. was cultured and an anthraquinone derivative, physcion (11.8 mg) was isolated from the culture broth extract (1710 mg). Physcion has shown cytotoxic effect on human cervical carcinoma HeLa cells and its apoptosis induction in HeLa cells was investigated by the expressions of p53, p21, Bax, Bcl-2, caspase-9, and caspase-3 proteins. The Western blot analysis has revealed that physcion could significantly induce cell apoptosis through down-regulating of Bcl-2 expression, up-regulating of Bax expression, and activating the caspase-3 pathway. Furthermore, physcion induced the formation of reactive oxygen species (ROS) in HeLa cells. Collectively, these results suggest that physcion could be a potential candidate in the field of anticancer drug discovery against human cervical cancer.

Secondary Metabolite Production by the Basidiomycete, Lentinus strigellus, under Different Culture Conditions

The basidiomycete Lentinus strigellus was cultivated in three different culture media and the secondary metabolites produced under different culture conditions were isolated and identified. When cultivated in a liquid medium with peptone, L. strigellus afforded the benzopyrans, 2,2-dimethyl-6-methoxychroman-4-one, 4-hydroxy-2,2-dimethyl-6-methoxychromane and (3 R,4 S)-3,4-dihydroxy-2,2-dimethyl-6-methoxychromane. The indole alkaloid echinuline and the anthraquinone fiscione, both unprecedented for the genus Lentinus, were isolated from the mycelium of the fungus. When cultured in Czapek medium enriched with potato broth, the fungus afforded the same benzopyrans except (3 S,4 S)-3,4-dihydroxy-2,2-dimethyl-6-methoxychromane. Panepoxydone and isopanepoxydone were also isolated when the microorganism was grown in Czapek medium.

Characterization of cytotoxic compound from mangrove derived fungi Irpex hydnoides VB4

OBJECTIVE

To investigate the cytotoxic activity of endophytic fungi isolated from mangrove fungi.

METHODS

In the present study the DNA was isolated and the ITS region of 5.8s rRNA was amplified using specific primers ITS 1 and ITS4 and sequence was determined using automated sequencers. Blast search sequence similarity was found against the existing non redundant nucleotide sequence database thus, identified as Aspergilus flavus, Hyporcaea lixii, Aspergillus niger, Eutorium amstelodami, Irpex hydnoides and Neurospora crassa. Among the seven isolates, one fungi Irpex hydnoides was selected for further studies. The fungi were grown in sabouraud broth for five days and filtrate were separated and subjected to ethyl acetate for further studies.

RESULTS

Nearly half (49.25%) of the extracts showed activity (IC50 of 125µg/mL). These values were within the cutoff point of the National Cancer Institute criteria for cytotoxicity (IC50<20 µg/mL) in the screening of crude plant extracts. The GC MS analysis revealed that the active principals might be Tetradecane (6.26%) with the RT 8.606.

CONCLUSIONS

It is clear from the present study that mangrove fungi with bioactive metabolites can be expected to provide high quality biological material for high throughout biochemical, anti cancer screening programmes. The results help us conclude that the potential of using metabolic engineering and post genomic approaches to isolate more novel bioactive compounds and to make their possible commercial application is not far off.