Cristazine, a novel dioxopiperazine alkaloid, induces apoptosis via the death receptor pathway in A431 cells.

The fungus Chaetomium sp. is a causative agent of infections in humans and is ubiquitous in the natural environment. The secondary metabolites of this genus exhibit many biological activities, including antifungal activity and toxicity in mitochondria. In this study, we isolated cristazine from the fungus C. cristatum, which has the potential to inhibit the growth of human epidermoid carcinoma (A431) cells in a dose- and time-dependent manner. Its inhibitory activity was examined using a cell viability assay and cell death was elucidated by western blot analysis. Cristazine triggered apoptotic cell death via the Type I death receptor pathway including the activation of caspases and other target proteins. However, cristazine did not have any effect on mitochondrial apoptotic proteins such as Bid, cytochrome c, and apoptosis-inducing factor. Cristazine inhibited the cell cycle progression by arresting the G1 /S phase and up-regulating the inhibitory proteins of cyclin-dependent kinases. Thus, cristazine has great potential for inducing apoptosis in A431 cells via both cell cycle arrest and the inhibition of cell growth.

Diacetoxyscirpenol as a new anticancer agent to target hypoxia-inducible factor 1.

Hypoxia activates hypoxia-inducible factor 1, which promotes the progression of malignancy by stimulating angiogenesis and by augmenting the ability of tumors to survive. Thus, HIF-1 is one of the most compelling targets for treating cancers. The aim of this study was to find a small molecule that inhibits HIF-1 under hypoxia in cancer cells. 7,280 compounds in a chemical library were tested in a cancer cell line expressing luciferase HIF-dependently. Through three rounds of screening, we finally picked up a compound that originates from a marine bacterium parasitizing red alga. The antibiotic potently inhibited HIF-1 expression and its transcriptional activity in cancer cells exposed to hypoxia. Through two-step fractionation, diacetoxyscirpenol was purified and identified as a HIF-inhibiting ingredient. Mechanistically, diacetoxyscirpenol inhibits the synthesis of HIF-1α protein and also interferes with the dimerization of HIF-1α and ARNT. It attenuates HIF-mediated gene expression in cancer cells exposed to hypoxia, and by doing so reduces tumorigenic and angiogenic potentials of cancer cells. More importantly, diacetoxyscirpenol retarded tumor growth in mice, and reduced HIF-1α expression and vascular formation in the tumors. Overall, diacetoxyscirpenol is considered a potential drug deregulating the HIF-1 signaling pathway, and it could be beneficially employed for treating malignant tumors with hypoxic microenvironment.

Induced production of 6,9-dibromoflavasperone, a new radical scavenging naphthopyranone in the marine-mudflat-derived fungus Aspergillus niger.

The addition of metal bromides (NaBr and CaBr2) during fermentation of the marine-mudflat-derived fungus Aspergillus niger induced production of a new radical scavenging brominated naphthopyranone, 6,9-dibromoflavasperone (1); and three known naphtho-γ-pyranone monomers, flavasperone (2), TMC-256A1 (3), and fonsecin (4); and one naphtho-γ-pyranone dimer, aurasperone B (5). The structure of 6,9-dibromoflavasperone (1) was assigned through the combination of spectroscopic data analyses and comparison with the spectral data of flavasperone (2). Compounds 1-5 displayed potent radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl, with IC50 values of 21, 25, 0.3, 0.02, and 0.01 µM, respectively, and 3-5 were more potent than the positive control, ascorbic acid (IC50, 20.0 µM).

Cristazine, a New Cytotoxic Dioxopiperazine Alkaloid from the Mudflat-Sediment-Derived Fungus Chaetomium cristatum.

Cristazine (1), a new class of dioxopiperazine alkaloid, along with previously isolated chetomin (2), neoechinulin A (3), and golmaenone (4), were isolated from the mudflat-sediment-derived fungus Chaetomium cristatum. The structure and absolute stereochemistry of 1 was assigned on the basis of NMR, electron impact (EI)-MS, tandem FAB-MS/MS, and circular dichroism (CD) experiments. Compounds 1-4 displayed potent radical-scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH), with IC50 values of 19, 15, 24, and 20 µM, respectively, which were similar to that of the positive control, ascorbic acid (IC50, 20 µM). Compound 1 also displayed cytotoxic activity against human cervical carcinoma (HeLa) cells, with an IC50 value of 0.5 µM.

Toluhydroquinone from Aspergillus sp. suppress inflammatory mediators via nuclear factor-κB and mitogen-activated protein kinases pathways in lipopolysaccharide-induced RAW264.7 cells.

OBJECTIVES: The purpose of this study is to investigate anti-inflammatory effects of toluhydroquinone in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. METHODS: Toluhydroquinone was purified from a fungal strain, Aspergillus sp. We investigated that levels of nitric oxide (NO) using Griess reagent, production of prostaglandin E2 (PGE2 ) and pro-inflammatory cytokines using ELISA assay. We conducted Western blot analysis to investigate regulatory effects of toluhydroquinone on expression of inducible nitric oxide synthase (iNOS), cyclooxyganse-2 (COX-2), nuclear factor-κB (NF-κB), Akt and mitogen-activated protein kinases (MAPKs) in LPS-stimulated RAW264.7 cells. The translocation of NF-κB was detected by immunofluorescence staining. KEY FINDINGS: Toluhydroquinone inhibited production of NO and PGE2 via suppressing protein expression of iNOS and COX-2, respectively. Secretion and expression of inflammatory cytokines were down-regulated by toluhydroquinone as well. Toluhydroquinone reduced phosphorylation of Akt, NF-κB and MAPKs. Moreover, toluhydroquinone inhibited translocation of NF-κB from the cytosol into the nucleus. CONCLUSIONS: We revealed that inhibitory effects of toluhydroquinone on expression of inflammatory mediators are induced through inactivation of Akt, NF-κB and MAPKs. Thus, our results suggest that toluhydroquinone may be used for a potential anti-inflammatory reagent.

Toluhydroquinone, the secondary metabolite of marine algae symbiotic microorganism, inhibits angiogenesis in HUVECs.

Angiogenesis, the growth of new blood vessels from the existing ones, occurs during embryo development and wound healing. However, most malignant tumors require angiogenesis for their growth and metastasis as well. Therefore, inhibition of angiogenesis has been focused as a new strategy of cancer therapies. To treat cancer, there are marine microorganism-derived secondary metabolites developed as chemotherapeutic agents. In this study, we used toluhydroquinone (2-methyl-1,4-hydroquinone), one of the secondary metabolites isolated from marine algae symbiotic fungus, Aspergillus sp. We examined the effects of toluhydroquinone on angiogenesis using HUVECs. We identified that toluhydroquinone inhibited the activity of ß-catenin and down-regulated Ras/Raf/MEK/ERK signaling which are crucial components during angiogenesis. In addition, the expression and activity of MMPs are reduced by the treatment of toluhydroquinone. In conclusion, we confirmed that toluhydroquinone has inhibitory effects on angiogenic behaviors of human endothelial cells, HUVECs. Our findings suggest that toluhydroquinone can be proposed as a potent anti-angiogenesis drug candidate to treat cancers.

3,4-dihydroxyphenyl acetic acid and (+)-epoxydon isolated from marine algae-derived microorganisms induce down regulation of epidermal growth factor activated mitogenic signaling cascade in Hela cells.

BACKGROUND: Epidermal growth factor receptor (EGFR) is a member of the receptor tyrosine kinase (RTK) family. Epidermal growth factor induces its dimerization and stimulates phosphorylation of intracellular tyrosine residues. Phosphorylation of EGFR is studied for cancer therapy because EGFR regulates many cellular processes including cell proliferation, differentiation, and survival. Hence, down-regulation of EGFR kinase activity results in inhibition of signaling cascades amenable for proliferation and progression of cell cycle. METHODS: In the study, we purified 3,4-dihydroxyphenyl acetic acid and (+)-epoxydon from Aspergillus sp. isolated from marine brown alga Ishige okamurae and Phoma herbarum isolated from marine red alga Hypnea saidana respectively and determined its anti-tumor activities against HeLa human cervical cancer cells. RESULTS: Two compounds suppressed EGFR activity in vitro with IC50 values for 3,4-dihydroxyphenyl acetic acid and (+)-epoxydon were 2.8 and 0.6 µg/mL respectively and reduced the viable numbers of HeLa cells. Immunoblotting analysis exhibited that the compounds induced inhibition of cell growth by causing downregulation of the mitogenic signaling cascade, inactivation of p90RSK, and release of cytochrome c from mitochondria. CONCLUSIONS: Results suggest that decreased expression of active EGFR and EGFR-related downstream molecules by treatment with the compounds may results in the inhibition of cell growth and inducement of apoptosis.

Induced production of methyl bromodihydroxyphenyl acetates by the marine-derived fungus Aspergillus sp.

The addition of metal bromides (NaBr and CaBr2) during fermentation of a marine isolate of the fungus Aspergillus sp. induced production of two new brominated dihydroxyphenylacetic acid derivatives, methyl 2-(6-bromo-3,4-dihydroxyphenyl)acetate (1) and methyl 2-(2,5-dibromo-3,4-dihydroxyphenyl)acetate (2), and a known compound, 2-(3,4-dihydroxyphenyl)acetic acid (3). The structures of the two new compounds (1, 2) were assigned through the combination of spectroscopic data analyses and comparison with the spectral data of compound 3. Compounds 1-3 exhibited potent radical-scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC50 values (14.2, 12.1, 11.0 µm, respectively) demonstrating greater activity than the positive control (l-ascorbic acid; IC50, 20.0 µm).

New production of 5-bromotoluhydroquinone and 4-O-methyltoluhydroquinone from the marine-derived fungus Dothideomycete sp.

The addition of NaBr to the fermentation medium of a marine isolate of the fungus Dothideomycete sp. resulted in induced production of two toluhydroquinone derivatives, 5- bromotoluhydroquinone (1) and 4-O-methyltoluhydroquinone (2), and two known compounds, toluhydroquinone (3) and gentisyl alcohol (4). The structures of 1 and 2 were assigned through the spectroscopic data analyses. Compounds 1-4 showed a potent antibacterial activity against the methicillinresistant and multidrug-resistant Staphylococcus aureus (MRSA and MDRSA) with MIC (minimum inhibitory concentration) values of 6.2, 12.5, 6.2, and 12.5 microgram/ml, respectively. Compounds 1-4 also exhibited a moderate radical scavenging activity against 1,1-diphenyl-2- picrylhydrazyl (DPPH) with IC(50) values of 11.0, 17.0, 12.0, and 7.0 microM, respectively, which were more active than the positive control, L-ascorbic acid (IC(50), 20.0 µM).

2-(4-Fluoro-phen-yl)-5,6-methyl-enedi-oxy-3-phenyl-sulfinyl-1-benzofuran monohydrate.

In the title compound, C(21)H(13)FO(4)S·H(2)O, the dihedral angles between the mean plane of the benzofuran fragment (r.m.s. deviation = 0.005 Å) and the pendant 4-fluoro-phenyl and phenyl rings are 6.24 (7) and 83.39 (6)°, respectively. In the crystal, mol-ecules are linked by O-H⋯O and C-H⋯O hydrogen bonds.

2-(5-Bromo-3-isopropyl-sulfanyl-1-benzofuran-2-yl)acetic acid.

The title compound, C(13)H(13)BrO(3)S, was prepared by alkaline hydrolysis of ethyl 2-(5-bromo-3-isopropyl-sulfanyl-1-benzofuran-2-yl)acetate. In the crystal, the carboxyl groups are involved in inter-molecular O-H⋯O hydrogen bonds, which link the mol-ecules into dimers. These dimers are further packed into stacks along the c axis by inter-molecular C-H⋯π inter-actions, and by slipped π-π inter-actions between the furan rings of adjacent mol-ecules [centroid-centroid distance = 3.472 (2) Å, inter-planar distance = 3.398 (2) Šand slippage = 0.713 (2) Å].

3-(4-Fluoro-phenyl-sulfon-yl)-5-iodo-2,7-dimethyl-1-benzofuran.

In the title compound, C(16)H(12)FIO(3)S, the 4-fluoro-phenyl ring makes a dihedral angle of 72.31 (6)° with the mean plane of the benzofuran fragment. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, and by an I⋯I contact [3.7764 (3) Å]. The crystal structure also exhibits a weak C-I⋯π [3.901 (3) Å] inter-action and a slipped π-π inter-action between the furan and benzene rings of neighbouring mol-ecules [centroid-centroid distance = 3.845 (3), inter-planar distance = 3.555 (3) and slippage = 1.465 (3) Å].

3-(3-Fluoro-phenyl-sulfon-yl)-2,5,7-trimethyl-1-benzofuran.

In the title compound, C(17)H(15)FO(3)S, the 3-fluoro-phenyl ring makes a dihedral angle of 73.39 (4)° with the mean plane of the benzofuran fragment. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds. The crystal structure also exhibits a slipped π-π inter-action between the furan and benzene rings of neighboring mol-ecules [centroid-centroid distance = 3.743 (2) Å, inter-planar distance = 3.543 (2) Šand slippage = 1.207 (2) Å].

2-(4-Fluoro-phen-yl)-3-isopropyl-sulfinyl-5,6-methyl-enedi-oxy-1-benzofuran.

In the title compound, C(18)H(15)FO(4)S, the fluoro-benzene ring makes a dihedral angle of 4.3 (1)° with the mean plane of the benzofuran fragment. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds. The O atom of the sulfinyl group is disordered over two orientations, with site-occupancy factors of 0.940 (3) and 0.060 (3).

5-Chloro-3-cyclo-pentyl-sulfonyl-2-methyl-1-benzofuran.

In the title compound, C(14)H(15)ClO(3)S, the cyclo-penyl ring adopts an envelope conformation. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds into dual chains propagating in [100]. The dual chains arise from pairs of the same or different hydrogen bonds between adjacent molecules.

3-Cyclo-hexyl-sulfonyl-2-methyl-5-propyl-1-benzofuran.

In the title compound, C(18)H(24)O(3)S, the cyclo-hexyl ring adopts a chair conformation. In the crystal, mol-ecules are linked through weak inter-molecular C-H⋯O hydrogen bonds and C-H⋯π inter-actions. In the propyl group, one C atom is disordered over two sites with site-occupancy factors of 0.546 (8) and 0.454 (8).

3-(3-Fluoro-phenyl-sulfin-yl)-2,4,5,6-tetra-methyl-1-benzofuran.

In the title compound, C(18)H(17)FO(2)S, the 3-fluoro-phenyl ring makes a dihedral angle of 78.60 (5)° with the mean plane of the benzofuran fragment. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds and weak inter-molecular C-S⋯π [3.490 (2) Å] inter-actions.

2-(4-Fluoro-phen-yl)-1-(phenyl-sulfin-yl)-naphtho-[2,1-b]furan.

In the title compound, C(24)H(15)FO(2)S, the 4-fluoro-phenyl ring makes a dihedral angle of 19.43 (4)° with the mean plane of the naphtho-furan fragment. The dihedral angle between the phenyl ring and the mean plane of the naphtho-furan fragment is 85.83 (4)°. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds.

5-Bromo-2-(4-fluoro-phen-yl)-3-phenyl-sulfinyl-1-benzofuran.

In the title compound, C(20)H(12)BrFO(2)S, the 4-fluoro-phenyl ring makes a dihedral angle of 2.63 (6)° with the mean plane of the benzofuran fragment. The dihedral angle between the phenyl ring and the mean plane of the benzofuran fragment is 84.60 (6)°. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds, and slipped π-π inter-actions between the benzene rings of neighbouring mol-ecules [centroid-centroid distance = 3.719 (3) Å, inter-planar distance = 3.000 (3) Šand slippage = 1.520 (3) Å].