Purification of Natural Pigments Violacein and Deoxyviolacein Produced by Fermentation Using Yarrowia lipolytica.

Violacein and deoxyviolacein are bis-indole pigments synthesized by a number of microorganisms. The present study describes the biosynthesis of a mixture of violacein and deoxyviolacein using a genetically modified Y. lipolytica strain as a production chassis, the subsequent extraction of the intracellular pigments, and ultimately their purification using column chromatography. The results show that the optimal separation between the pigments occurs using an ethyl acetate/cyclohexane mixture with different ratios, first 65:35 until both pigments were clearly visible and distinguishable, then 40:60 to create a noticeable separation between them and recover the deoxyviolacein, and finally 80:20, which allows the recovery of the violacein. The purified pigments were then analyzed by thin-layer chromatography and nuclear magnetic resonance.

iTRAQ-Based Proteomics Analysis of Response to Solanum tuberosum Leaves Treated with the Plant Phytotoxin Thaxtomin A.

Thaxtomin A (TA) is a phytotoxin secreted by Streptomyces scabies that causes common scab in potatoes. However, the mechanism of potato proteomic changes in response to TA is barely known. In this study, the proteomic changes in potato leaves treated with TA were determined using the Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) technique. A total of 693 proteins were considered as differentially expressed proteins (DEPs) following a comparison of leaves treated with TA and sterile water (as a control). Among the identified DEPs, 460 and 233 were upregulated and downregulated, respectively. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, many DEPs were found to be involved in defense and stress responses. Most DEPs were grouped in carbohydrate metabolism, amino acid metabolism, energy metabolism, and secondary metabolism including oxidation-reduction process, response to stress, plant-pathogen interaction, and plant hormone signal transduction. In this study, we analyzed the changes in proteins to elucidate the mechanism of potato response to TA, and we provided a molecular basis to further study the interaction between plant and TA. These results also offer the option for potato breeding through analysis of the resistant common scab.

First observation on the predation of a non-arthropod species by a dung beetle species: The case of Canthon chalybaeus and the snail Bulimulus apodemetes.

We described, for the first time, a case of predation of a non-arthropod species by a dung beetle species. Canthon chalybaeus Blanchard, 1843 kills healthy individuals of the terrestrial snail Bulimulus apodemetes (D'Orbigny, 1835) showing an evident pattern of physical aggressiveness in the attacks using the dentate clypeus and the anterior tibiae. The description of this predatory behaviour was complemented with the analysis of the chemical secretions of the pygidial glands of C. chalybaeus, highlighting those main chemical compounds that, due to their potential toxicity, could contribute to death of the snail. We observed a high frequency of predatory interactions reinforcing the idea that predation in dung beetles is not accidental and although it is opportunistic it involves a series of behavioural sophistications that suggest an evolutionary pattern within Deltochilini that should not only be better studied from a behavioural point of view but also phylogenetically.

Indole Glycosides from Calanthe discolor with Proliferative Activity on Human Hair Follicle Dermal Papilla Cells.

A methanol extract from the underground part of Calanthe discolor Lindl. (Orchidaceae) demonstrated significant proliferative activity on human hair follicle dermal papilla cells (HFDPC, % of control: 120.8 ± 0.2%) at 100 µg/mL against HFDPC. Through bioassay-guided separation of the extract, a new indole glycoside named 6'-O-ß-D-apiofuranosylindican (1) was isolated along with six known compounds (2-7) including three indole glycosides. The stereostructure of 1 was elucidated based on its spectroscopic properties and chemical characteristics. Among the isolates, 1 (110.0 ± 1.0%), glucoindican (3, 123.9 ± 6.8%), and calanthoside (4, 158.6 ± 7.1%) showed significant proliferative activity at 100 µM. Furthermore, the active indole glycosides (1, 3, and 4) upregulated the expression of vascular endothelial growth factor (VEGF) and fibroblast growth factor-7 (FGF-7) mRNA and protein in HFDPC, which could be the mechanism of their proliferative activity.

Structural-Based Optimizations of the Marine-Originated Meridianin C as Glucose Uptake Agents by Inhibiting GSK-3ß.

Glycogen synthase kinase 3ß (GSK-3ß) is a widely investigated molecular target for numerous diseases, and inhibition of GSK-3ß activity has become an attractive approach for the treatment of diabetes. Meridianin C, an indole-based natural product isolated from marine Aplidium meridianum, has been reported as a potent GSK-3ß inhibitor. In the present study, applying the structural-based optimization strategy, the pyrimidine group of meridianin C was modified by introducing different substituents based on the 2-aminopyrimidines-substituted pyrazolo pyridazine scaffold. Among them, compounds B29 and B30 showed a much higher glucose uptake than meridianin C (<5%) and the positive compound 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8, 16%), with no significant toxicity against HepG2 cells at the same time. Furthermore, they displayed good GSK-3ß inhibitory activities (IC50 = 5.85; 24.4 µM). These results suggest that these meridianin C analogues represent novel lead compounds with therapeutic potential for diabetes.

Biotechnological Production of the Sunscreen Pigment Scytonemin in Cyanobacteria: Progress and Strategy.

Scytonemin is a promising UV-screen and antioxidant small molecule with commercial value in cosmetics and medicine. It is solely biosynthesized in some cyanobacteria. Recently, its biosynthesis mechanism has been elucidated in the model cyanobacterium Nostoc punctiforme PCC 73102. The direct precursors for scytonemin biosynthesis are tryptophan and p-hydroxyphenylpyruvate, which are generated through the shikimate and aromatic amino acid biosynthesis pathway. More upstream substrates are the central carbon metabolism intermediates phosphoenolpyruvate and erythrose-4-phosphate. Thus, it is a long route to synthesize scytonemin from the fixed atmospheric CO2 in cyanobacteria. Metabolic engineering has risen as an important biotechnological means for achieving sustainable high-efficiency and high-yield target metabolites. In this review, we summarized the biochemical properties of this molecule, its biosynthetic gene clusters and transcriptional regulations, the associated carbon flux-driving progresses, and the host selection and biosynthetic strategies, with the aim to expand our understanding on engineering suitable cyanobacteria for cost-effective production of scytonemin in future practices.

Asperorydines N-P, three new cyclopiazonic acid alkaloids from the marine-derived fungus Aspergillus flavus SCSIO F025.

Three new tricyclic cyclopiazonic acid (CPA) related alkaloids asperorydines N-P (1-3), together with six known compounds (4-9) were isolated and characterized from the fungus Aspergillus flavus SCSIO F025 derived from the deep-sea sediments of South China Sea. The structures including absolute configurations of 1-3 were deduced from spectroscopic data, X-ray diffraction analysis, and electronic circular dichroism (ECD). All compounds were evaluated for the antioxidative activities against DPPH, cytotoxic activities against four tumor cell lines (SF-268, HepG-2, MCF-7, and A549), and antimicrobial activities. Compound 9 showed significant radical scavenging activities against DPPH with an IC50 value of 62.23 µM and broad-spectrum cytotoxicities against four tumor cell lines with IC50 values ranging from 24.38 to 48.28 µM. Furthermore, compounds 4-9 exhibited weak antimicrobial activities against E scherichia coli, and compound 9 also showed antibacterial activity against Bacillus thuringiensis, Micrococcus lutea, Staphylococcus aureus, Bacillus subtilis, Methicillin resistant Staphylococcus aureus.

New Deoxyisoaustamide Derivatives from the Coral-Derived Fungus Penicillium dimorphosporum KMM 4689.

Seven new deoxyisoaustamide derivatives (1-7) together with known compounds (8-10) were isolated from the coral-derived fungus Penicillium dimorphosporum KMM 4689. Their structures were established using spectroscopic methods, X-ray diffraction analysis and by comparison with related known compounds. The absolute configurations of some alkaloids were determined based on CD and NOESY data as well as biogenetic considerations. The cytotoxic and neuroprotective activities of some of the isolated compounds were examined and structure-activity relationships were pointed out. New deoxyisoaustamides 4-6 at concentration of 1 µM revealed a statistical increase of PQ(paraquat)-treated Neuro-2a cell viability by 30-39%.

(R)-3-(8'-Hydroxyfarnesyl)-indole and other chemical constituents from the flowers of Anomianthus dulcis and their antimalarial and cytotoxic activities.

A new farnesylindole, (R)-3-(8'-hydroxyfarnesyl)-indole (1), as a scalemic mixture (33% ee) along with nine known compounds (2-10), including one farnesylindole, three flavanones, three flavone derivatives and two chalcone derivatives were isolated from the methanolic crude extract of the flowers from Anomianthus dulcis. All compounds were purified by appropriate chromatographic techniques and their structures elucidated by spectroscopic methods. Compounds 1, 2 and 8 showed moderate antiplasmodial activities against TM4/8.Two and K1CB1 strains of which compound 2 displayed the best activity with IC50 values of 27.9 ± 2.57 and 21.4 ± 1.68 µM, respectively. In addition, compound 1 also presented modest cytotoxicity against a KB cell line with an IC50 value of 22.3 ± 0.39 µM. None of these compounds showed cytotoxicity against Vero cells.

Phytocompounds curcumin, quercetin, indole-3-carbinol, and resveratrol modulate lactate-pyruvate level along with cytotoxic activity in HeLa cervical cancer cells.

Cancer cells meet their energy need by predominantly increased uptake of glucose, high rate of glycolysis, and increased production of lactate even in the presence of adequate oxygen.  This process was proposed by Otto Warburg and named after him as the Warburg effect. The development of drugs that target glucose intake and aerobic glycolysis or lactic acid secretion of cancer cells is a newer approach for drug discovery. We have tested five purified plants-derived compounds such as curcumin, quercetin, ellagic acid, resveratrol, and indole-3-carbinol in HeLa cells for cytotoxicity, inhibition of metastasis, and modulation of lactate-pyruvate metabolism. Standard biochemical methods were used for glucose, lactic acid, and pyruvic acid measurement. The cell viability was determined by MTT assay. Cell migration was checked by wound healing assay. A dose-dependent cytotoxic effect and inhibition of cell migration were observed in all the tested compounds. A decrease in the lactate and increase in pyruvate level was observed in all the tested compounds except ellagic acid. Our finding suggests that tested phytocompounds are associated with the metabolic reprogramming of cancer cells and execute the cytotoxic effect. These compounds could be used for cancer prevention and therapy.

Differentiation of Positional Isomers of Halogenated Benzoylindole Synthetic Cannabinoid Derivatives in Serum by Hybrid Quadrupole/Orbitrap Mass Spectrometry.

Legally regulated synthetic cannabinoids (SCs) are continuously being created by making minor positional modifications to pre-existing analogs; thus, compounds with minor structural differences must be isolated and identified accurately. For iodo-benzoylindole derivatives of SCs, only specific isomers are currently the target of legal control, and it is necessary to establish an analytical method for accurately identifying positional isomers. In this study, we synthesized a series of 57 designer drugs and developed a screening method for identifying halogen positional isomers on the phenyl ring of benzoylindole derivative SCs in serum. Analytical methods using the Discovery F5 pentafluorophenyl column gave the best selectivity and retention of the positional isomer analytes. Some of the meta and para iodo-substituted SCs were eluted at similar retention times and were difficult to separate by liquid chromatography (LC). However, they were identified via the relative abundance of the two product ions in the collision-induced dissociation reaction using LC-hybrid quadrupole/orbitrap high-resolution mass spectrometry. Our synthesized halogen-substituted positional isomer SC library and method for differentiating positional isomers of halogenated benzoylindole SC derivatives could provide an indispensable analysis tool for identifying illegal drugs in serum of drug users.

Isolation and Pharmacological Characterization of Six Opioidergic Picralima nitida Alkaloids.

The seeds of the akuamma tree (Picralima nitida) have been used as a traditional treatment for pain and fever. Previous studies have attributed these effects to a series of indole alkaloids found within the seed extracts; however, these pharmacological studies were significantly limited in scope. Herein, an isolation protocol employing pH-zone-refining countercurrent chromatography was developed to provide six of the akuamma alkaloids in high purity and quantities sufficient for more extensive biological evaluation. Five of these alkaloids, akuammine (1), pseudo-akuammigine (3), akuammicine (4), akuammiline (5), and picraline (6), were evaluated against a panel of >40 central nervous system receptors to identify that their primary targets are the opioid receptors. Detailed in vitro investigations revealed 4 to be a potent kappa opioid receptor agonist, and three alkaloids (1-3) were shown to have micromolar activity at the mu opioid receptor. The mu opioid receptor agonists were further evaluated for analgesic properties but demonstrated limited efficacy in assays of thermal nociception. These findings contradict previous reports of the antinociceptive properties of the P. nitida alkaloids and the traditional use of akuamma seeds as analgesics. Nevertheless, their opioid-preferring activity does suggest the akuamma alkaloids provide distinct scaffolds from which novel opioids with unique pharmacologic properties and therapeutic utility can be developed.

Production of Tyrian purple indigoid dye from tryptophan in Escherichia coli.

Tyrian purple, mainly composed of 6,6'-dibromoindigo (6BrIG), is an ancient dye extracted from sea snails and was recently demonstrated as a biocompatible semiconductor material. However, its synthesis remains limited due to uncharacterized biosynthetic pathways and the difficulty of regiospecific bromination. Here, we introduce an effective 6BrIG production strategy in Escherichia coli using tryptophan 6-halogenase SttH, tryptophanase TnaA and flavin-containing monooxygenase MaFMO. Since tryptophan halogenases are expressed in highly insoluble forms in E. coli, a flavin reductase (Fre) that regenerates FADH2 for the halogenase reaction was used as an N-terminal soluble tag of SttH. A consecutive two-cell reaction system was designed to overproduce regiospecifically brominated precursors of 6BrIG by spatiotemporal separation of bromination and bromotryptophan degradation. These approaches led to 315.0 mg l-1 6BrIG production from tryptophan and successful synthesis of regiospecifically dihalogenated indigos. Furthermore, it was demonstrated that 6BrIG overproducing cells can be directly used as a bacterial dye.

Dietary Indole-3-Carbinol Alleviated Spleen Enlargement, Enhanced IgG Response in C3H/HeN Mice Infected with Citrobacter rodentium.

Enteropathogenic and enterohemorrhagic Escherichia coli are important enteric pathogens that induce hemorrhagic colitis or even fatal hemolytic uremic syndrome. Emerging evidence shows that some bio-actives derived from fruits and vegetables may serve as alternatives to antibiotics for overcoming multidrug resistant E. coli infections. In this study, the Citrobacter rodentium (Cr) infection model was utilized to mimic E. coli-induced acute intestinal inflammation, and the effects of a cruciferous vegetable-derived cancer protective compound, indole-3-carbinol (I3C), on the immune responses of Cr-susceptible C3H/HeN mice were investigated. Dietary I3C significantly inhibited the loss of body weight and the increase in spleen size in Cr infected mice. In addition, I3C treatment reduced the inflammatory response to Cr infection by maintaining anti-inflammatory cytokine IL-22 mRNA levels while reducing expression of other pro-inflammatory cytokines including IL17A, IL6, IL1ß, TNF-α, and IFN-γ. Moreover, the serum cytokine levels of IL17, TNF-α, IL12p70, and G-CSF also were down-regulated by I3C in Cr-infected mice. Additionally, dietary I3C specifically enhanced the Cr-specific IgG response to Cr infection. In general, dietary I3C reduced the Cr-induced pro-inflammatory response in susceptible C3H/HeN mice and alleviated the physiological changes and tissue damage induced by Cr infection but not Cr colonization.

Indole-6-Carboxaldehyde Isolated from Sargassum thunbergii (Mertens) Kuntze Prevents Oxidative Stress-Induced Cellular Damage in V79-4 Chinese Hamster Lung Fibroblasts through the Activation of the Nrf2/HO-1 Signaling Pathway.

BACKGROUND/AIMS: The disruption of redox equilibrium by oxidative stress, which is characterized by an overproduction of reactive oxygen species (ROS), is considered to be associated with fibroblast death in severe lung diseases. Indole-6-carboxaldehyde (I6CA) is a natural indole derivative isolated from Sargassum thunbergii, which a type of brown algae. However, the antioxidative effects of I6CA, and their mechanisms, have not been identified. This study was conducted to investigate the potential protective effects of I6CA against oxidative stress in V79-4 Chinese hamster lung fibroblasts. METHODS: Cell viability and mechanisms related to antioxidant activity of I6CA (ROS production, cell cycle, DNA damage, mitochondrial membrane potential (MMP) and apoptosis) were studied. Western blot analysis was carried out to understand the involvement of various genes at protein level. RESULTS: Our results demonstrated that I6CA inhibited hydrogen peroxide (H2O2)-induced cytotoxicity by blocking abnormal ROS accumulation. H2O2 treatment of V79-4 fibroblasts caused cell cycle arrest at the G2/M phase, which was accompanied by increased expression of the cyclin-dependent kinase (Cdk) inhibitor p21WAF1/CIP1 and decreased expression of cyclin B1 and cyclin A. However, these effects were attenuated by treatment with I6CA. I6CA also effectively protected V79-4 cells against H2O2-induced apoptosis by increasing the Bcl-2/Bax ratio and suppressing the loss of MMP and the cytosolic release of cytochrome c. In addition, the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2) was markedly promoted by I6CA, which was associated with enhanced expression and activity of heme oxygenase-1 (HO-1). However, inhibiting the activity of HO-1 by zinc protoporphyrin IX, a potent inhibitor of HO-1, eliminated the ROS scavenging and anti-apoptotic effects of I6CA, indicating that I6CA was able to protect V79-4 lung fibroblasts from H2O2-induced oxidative stress by activating the Nrf2 signaling pathway. CONCLUSION: We suggest that I6CA may be useful as a candidate therapeutic agent for the treatment of oxidative stress-related lung diseases.

A new ent-abietane lactone from Glycosmis pentaphylla.

A new ent-abietane lactone, 3-oxojolkinolide A (1), together with 16 known compounds, helioscopinolide E (2), helioscopinolide A (3), 3-methyl-9H-carbazole (4), carbalexin (5), carbalexin B (6), glycaborinine (7), arborinine (8), 1H-indole-3-carbaldehyde (9), glycoamide A (10), glycoamide B (11), 2-(N-methyl-2-phenylacetamido)benzoic acid (12), 2-(methylamine)-methylbenzoate (13), fraxidin (14), scopoletin (15), (-)-syringaresinol (16) and ferulic acid (17) were isolated from Glycosmis pentaphylla. The structures of these compounds were elucidated using spectroscopic techniques such as NMR and MS. Among them, compounds 1-3, 9 and 12-17 were isolated from the genus Glycosmis for the first time.

Isolation and Antibacterial Activity of Indole Alkaloids from Pseudomonas aeruginosa UWI-1.

In this study, we report the first isolation of three antibiotic indole alkaloid compounds from a Pseudomonad bacterium, Pseudomonas aeruginosa UWI-1. The bacterium was batch fermented in a modified Luria Broth medium and compounds were solvent extracted and isolated by bioassay-guided fractionation. The three compounds were identified as (1) tris(1H-indol-3-yl) methylium, (2) bis(indol-3-yl) phenylmethane, and (3) indolo (2, 1b) quinazoline-6, 12 dione. A combination of 1D and 2D NMR, high-resolution mass spectrometry data and comparison from related data from the literature was used to determine the chemical structures of the compounds. Compounds 1-3 were evaluated in vitro for their antimicrobial activities against a wide range of microorganisms using the broth microdilution technique. Compounds 1 and 2 displayed antibacterial activity against only Gram-positive pathogens, although 1 had significantly lower minimum inhibitory concentration (MIC) values than 2. Compound 3 displayed potent broad-spectrum antimicrobial activity against a range of Gram positive and negative bacteria. Several genes identified from the genome of P. aeruginosa UWI-1 were postulated to contribute to the biosynthesis of these compounds and we attempted to outline a possible route for bacterial synthesis. This study demonstrated the extended metabolic capability of Pseudomonas aeruginosa in synthesizing new chemotypes of bioactive compounds.

Brassinin, a brassica-derived phytochemical, regulates monocyte-to-macrophage differentiation and inflammatory responses in human monocytes and murine macrophages.

OBJECTIVES: The effects and molecular mechanisms of brassinin (BR), an indole phytoalexin from cruciferous vegetables, on monocyte-to-macrophage differentiation and inflammatory responses were investigated in this study. METHODS: Inflammatory responses from RAW264.7 cells and THP-1 were stimulated by lipopolysaccharide (1 µg/ml), and monocyte-to-macrophage differentiation of THP-1 was induced by phorbol myristate acetate (50 ng/ml). The production of inflammatory mediators was determined by ELISA, Western blot or real-time PCR. Reactive oxygen species were examined by DCFH-DA assay. KEY FINDINGS: Brassinin at 50 µm suppressed lipopolysaccharide-induced production of nitric oxide synthase, cyclooxygenase-2, prostaglandin E2 and reactive oxygen species by 90%, 69%, 52% and 41%, respectively, in RAW264.7 cells. In THP-1 cells, BR inhibited phorbol myristate acetate-induced monocyte-to-macrophage differentiation by suppressing cluster of differentiation molecule ß and CD36. In addition, BR suppressed translocation of nuclear factor 'kappa-light-chain-enhancer' of activated B cells (NF-κB) into the nucleus. However, BR activated the nuclear factor erythroid-derived 2-like 2 (Nrf2) and its target molecules hemoxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1), with an increase in nuclear translocation of Nrf2. CONCLUSIONS: Brassinin suppressed monocyte-to-macrophage differentiation and inflammatory responses by differentially regulating Nrf2 and NF-κB signallings.

New Indole Diketopiperazine Alkaloids from Soft Coral-Associated Epiphytic Fungus Aspergillus sp. EGF 15-0-3.

Three new indole diketopiperazine alkaloids, 11-methylneoechinulin E and variecolorin M, and (+)-variecolorin G, along with 12 known analogs, were isolated from a soft coral-associated epiphytic fungus Aspergillus sp. EGF 15-0-3. The structures of the new compounds were unambiguously established by extensive spectroscopic analyses including HR-ESI-MS, 1D and 2D NMR spectroscopy and optical rotation measurements. The absolute configurations of (+)- and (-)-variecolorin G were determined by experimental and quantum-chemical ECD investigations and single-crystal X-ray diffraction analysis. Variecolorin G is a pair of enantiomeric mixtures with a ratio of 1 : 2. Moreover, (+)-neoechinulin A is firstly reported as a natural product. The cytotoxic activities of all the isolated compounds against NCI-H1975 gefitinib resistance (NCI-H1975/GR) cell lines were preliminarily evaluated by MTT method.

Characterization and bioactive potentials of secondary metabolites from Fusarium chlamydosporum.

A search for bioactive secondary metabolites from the endophytic fungus Fusarium chlamydosporum, isolated from the root of Suaeda glauca, led to the isolation of three indole derivatives (1-3), three cyclohexadepsipeptides (4-6), and four pyrones (7-10). The structures of new (1) and known compounds (2-10) were elucidated on the basis of extensive spectroscopic analysis. All these compounds were evaluated for phytotoxic, antimicrobial activities, and brine shrimp lethality. Compound 1 showed significant phytotoxic activity against the radicle growth of Echinochloa crusgalli, even better than the positive control of 2,4-D. Cyclohexadepsipeptides (4-6) and pyrones (7-10) exhibited brine shrimp lethality, especially 4 and 7 with the LD50 values of 2.78 and 7.40 µg mL-1, respectively, better than the positive control.