Inhibitors of Transthyretin Amyloidosis: How to Rank Drug Candidates Using X-ray Crystallography Data.

Amyloidosis is a group of protein misfolding diseases, which include spongiform encephalopathies, Alzheimer's disease and transthyretin (TTR) amyloidosis; all of them are characterized by extracellular deposits of an insoluble fibrillar protein. TTR amyloidosis is a highly debilitating and life-threatening disease. Patients carry less stable TTR homotetramers that are prone to dissociation into non-native monomers, which in turn rapidly self-assemble into oligomers and, ultimately, amyloid fibrils. Liver transplantation to induce the production of wild-type TTR was the only therapeutic strategy until recently. A promising approach to ameliorate transthyretin (TTR) amyloidosis is based on the so-called TTR kinetic stabilizers. More than 1000 TTR stabilizers have already been tested by many research groups, but the diversity of experimental techniques and conditions used hampers an objective prioritization of the compounds. One of the most reliable and unambiguous techniques applied to determine the structures of the TTR/drug complexes is X-ray diffraction. Most of the potential inhibitors bind in the TTR channel and the crystal structures reveal the atomic details of the interaction between the protein and the compound. Here we suggest that the stabilization effect is associated with a compaction of the quaternary structure of the protein and propose a scoring function to rank drugs based on X-ray crystallography data.

Crystal structures of Streptomyces tsukubaensis sigma factor SigG1 and anti-sigma RsfG.

Transcription of specific genes in bacteria under environmental stress is frequently initiated by extracytoplasmic function (ECF) σ factors. ECFs σ factors harbour two conserved domains, σ2 and σ4, for transcription initiation by recognition of the promoter region and recruitment of RNA polymerase (RNAP). The crystal structure of Streptomyces tsukubaensis SigG1, an ECF56-family σ factor, was determined revealing σ2, σ4 and the additional carboxi-terminal domain SnoaL_2 tightly packed in a compact conformation. The structure of anti-sigma RsfG was also determined by X-ray crystallography and shows a rare ß-barrel fold. Analysis of the metal binding motifs inside the protein barrel are consistent with Fe(III) binding, which is in agreement with previous findings that the Streptomyces tsukubaensis ECF56 SigG1-RsfG system is involved in metal-ion homeostasis.

Pentaketides and 5-p-Hydroxyphenyl-2-pyridone Derivative from the Culture Extract of a Marine Sponge-Associated Fungus Hamigera avellanea KUFA0732.

Five undescribed pentaketide derivatives, (R)-6,8-dihydroxy-4,5-dimethyl-3-methylidene-3,4-dihydro-1H-2-benzopyran-1-one (1), [(3S,4R)-3,8-dihydroxy-6-methoxy-4,5-dimethyl-1-oxo-3,4-dihydro-1H-isochromen-3-yl]methyl acetate (2), (R)-5, 7-dimethoxy-3-((S)-(1-hydroxyethyl)-3,4-dimethylisobenzofuran-1(3H)-one (4b), (S)-7-hydroxy-3-((S)-1-hydroxyethyl)-5-methoxy-3,4-dimethylisobenzofuran 1(3H)-one (5), and a p-hydroxyphenyl-2-pyridone derivative, avellaneanone (6), were isolated together with the previously reported (R)-3-acetyl-7-hydroxy-5-methoxy-3,4-dimethylisobenzofuran-1(3H)-one (3), (R)-7-hydroxy-3-((S)-1-hydroxyethyl)-5-methoxy-3,4-dimethylisobenzofuran-1(3H)-one (4a) and isosclerone (7), from the ethyl acetate extract of a culture of a marine sponge-derived fungus, Hamigera avellanea KUFA0732. The structures of the undescribed compounds were elucidated using 1D and 2D NMR, as well as high-resolution mass spectral analyses. The absolute configurations of the stereogenic carbons in 1, 4b, 5, and 6 were established by X-ray crystallographic analysis. The absolute configurations of C-3 and C-4 in 2 were determined by ROESY correlations and on the basis of their common biosynthetic origin with 1. The crude fungal extract and the isolated compounds 1, 3, 4b, 5, 6, and 7 were assayed for their growth inhibitory activity against various plant pathogenic fungi viz. Alternaria brassicicola, Bipolaris oryzae, Colletotrichum capsici, C. gloeosporiodes, Curvularia oryzae, Fusarium semitectum, Lasiodiplodia theobromae, Phytophthora palmivora, Pyricularia oryzae, Rhizoctonia oryzae and Sclerotium rolfsii.

New Hybrid Phenalenone Dimer, Highly Conjugated Dihydroxylated C28 Steroid and Azaphilone from the Culture Extract of a Marine Sponge-Associated Fungus, Talaromyces pinophilus KUFA 1767.

An undescribed hybrid phenalenone dimer, talaropinophilone (3), an unreported azaphilone, 7-epi-pinazaphilone B (4), an unreported phthalide dimer, talaropinophilide (6), and an undescribed 9R,15S-dihydroxy-ergosta-4,6,8 (14)-tetraen-3-one (7) were isolated together with the previously reported bacillisporins A (1) and B (2), an azaphilone derivative, Sch 1385568 (5), 1-deoxyrubralactone (8), acetylquestinol (9), piniterpenoid D (10) and 3,5-dihydroxy-4-methylphthalaldehydic acid (11) from the ethyl acetate extract of the culture of a marine sponge-derived fungus, Talaromyces pinophilus KUFA 1767. The structures of the undescribed compounds were elucidated by 1D and 2D NMR as well as high-resolution mass spectral analyses. The absolute configuration of C-9' of 1 and 2 was revised to be 9'S using the coupling constant value between C-8' and C-9' and was confirmed by ROESY correlations in the case of 2. The absolute configurations of the stereogenic carbons in 7 and 8 were established by X-ray crystallographic analysis. Compounds 1,2, 4-8, 10 and 11 were tested for antibacterial activity against four reference strains, viz. two Gram-positive (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and two Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853), as well as three multidrug-resistant strains, viz. an extended-spectrum ß-lactamase (ESBL)-producing E. coli, a methicillin-resistant S. aureus (MRSA) and a vancomycin-resistant E. faecalis (VRE). However, only 1 and 2 exhibited significant antibacterial activity against both S. aureus ATCC 29213 and MRSA. Moreover, 1 and 2 also significantly inhibited biofilm formation in S. aureus ATCC 29213 at both MIC and 2xMIC concentrations.

New Alkylpyridinium Anthraquinone, Isocoumarin, C-Glucosyl Resorcinol Derivative and Prenylated Pyranoxanthones from the Culture of a Marine Sponge-Associated Fungus, Aspergillus stellatus KUFA 2017.

An unreported isocoumarin, (3S,4R)-4-hydroxy-6-methoxymellein (2), an undescribed propylpyridinium anthraquinone (4), and an unreported C-glucosyl resorcinol derivative, acetyl carnemycin E (5c), were isolated, together with eight previously reported metabolites including p-hydroxybenzaldehyde (1), 1,3-dimethoxy-8-hydroxy-6-methylanthraquinone (3a), 1,3-dimethoxy-2,8-dihydroxy-6-methylanthraquinone (3b), emodin (3c), 5[(3E,5E)-nona-3,5-dien-1-yl]benzene (5a), carnemycin E (5b), tajixanthone hydrate (6a) and 15-acetyl tajixanthone hydrate (6b), from the ethyl acetate extract of the culture of a marine sponge-derived fungus, Aspergillus stellatus KUFA 2017. The structures of the undescribed compounds were elucidated by 1D and 2D NMR and high resolution mass spectral analyses. In the case of 2, the absolute configurations of the stereogenic carbons were determined by comparison of their calculated and experimental electronic circular dichroism (ECD) spectra. The absolute configurations of the stereogenic carbons in 6a and 6b were also determined, for the first time, by X-ray crystallographic analysis. Compounds 2, 3a, 3b, 4, 5a, 5b, 5c, 6a, and 6b were assayed for antibacterial activity against four reference strains, viz. two Gram-positive (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and two Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853), as well as three multidrug-resistant strains. However, only 5a exhibited significant antibacterial activity against both reference and multidrug-resistant strains. Compound 5a also showed antibiofilm activity against both reference strains of Gram-positive bacteria.

Antibacterial and Antibiofilm Properties of Self-Assembled Dipeptide Nanotubes.

Over recent decades, multidrug-resistant pathogens have become a global concern, with WHO even considering it one of the biggest threats to global health, food security, and development today, which led to the search for alternative antibacterial agents. A special class is formed by peptides composed by the diphenylalanine motif whose antibacterial properties result from their supramolecular arrangement into nanotubes. However, several other dipeptides that also form nanotubes have been largely overlooked. Here, we present the antibacterial activity of four dipeptide nanotubes. The results point to diverse mechanisms through which dipeptide nanotubes exert their effect against bacteria. Antibacterial activity was similar for dipeptide nanotubes sufficiently wide to allow water flux while dipeptides displaying smaller channels were inactive. This suggests that two of the tested dipeptides, L-Phe-L-Phe (FF, diphenylalanine) and L-Leu-L-Ser (LS), are pore forming structures able to induce membrane permeation and affect cellular hydration and integrity. Of these two dipeptides, only FF demonstrated potential to inhibit biofilm formation. The amyloid-like nature and hydrophobicity of diphenylalanine assemblies are probably responsible for their adhesion to cell surfaces preventing biofilm formation and bacteria attachment.

Metal-organic frameworks: a future toolbox for biomedicine?

The present review focuses on the use of Metal-Organic Frameworks, (MOFs) highlighting the most recent developments in the biological field. This review assesses, in the first instance, the cytotoxicity of MOFs (particularly those used for various biological applications described throughout this review), and shows that for standard MOFs based on metals already present in active molecules of the human body, toxicity is not a significant limitation. Here we underline the MIL-, UiO- and ZIF-series of MOFs which remain until now the most used materials in drug delivery of active pharmaceutical ingredients (APIs), such as antitumourals or retroviral drugs (with high loading and slow release time). Porosity remains undoubtedly the most studied key property of MOFs, that allows the protection of active biomolecules such as enzymes or the development of antimicrobial materials. Emphasis is given on the usage of MOFs for the detection of biomarkers in biological fluids such as urine and blood (detection of cystinuria, identification of penicillin anaphylaxis, urea, bilirubin, biomarkers related to human intoxication, tumoural indicators, among several others), for which a number of simple devices (such as paper strips) were developed. Despite the remarkable and promising results presented in recent years, the literature remains scarce (mostly non-existent) in terms of direct comparison of these novel technologies with the solutions presently available in the market. Action on this side may make the difference in the next years concerning research on MOFs, to see if some of these materials may reach the end-user as new and more efficient treatments or detection approaches.

Semi-Synthesis of Small Molecules of Aminocarbazoles: Tumor Growth Inhibition and Potential Impact on p53.

The tumor suppressor p53 is inactivated by mutation in approximately 50% of human cancers. Small molecules that bind and stabilize those mutants may represent effective anticancer drugs. Herein, we report the tumor cell growth inhibitory activity of carbazole alkaloids and amino derivatives, as well as their potential activation of p53. Twelve aminocarbazole alkaloids were semi-synthesized from heptaphylline (1), 7-methoxy heptaphylline (2), and 7-methoxymukonal (3), isolated from Clausena harmandiana, using a reductive amination protocol. Naturally-occurring carbazoles 1-3 and their amino derivatives were evaluated for their potential effect on wild-type and mutant p53 activity using a yeast screening assay and on human tumor cell lines. Naturally-occurring carbazoles 1-3 showed the most potent growth inhibitory effects on wild-type p53-expressing cells, being heptaphylline (1) the most promising in all the investigated cell lines. However, compound 1 also showed growth inhibition against non-tumor cells. Conversely, semi-synthetic aminocarbazole 1d showed an interesting growth inhibitory activity in tumor cells expressing both wild-type and mutant p53, exhibiting low growth inhibition on non-tumor cells. The yeast assay showed a potential reactivation of mutant p53 by heptaphylline derivatives, including compound 1d. The results obtained indicate that carbazole alkaloids may represent a promising starting point to search for new mutp53-reactivating agents with promising applications in cancer therapy.

Tetracyclic Thioxanthene Derivatives: Studies on Fluorescence and Antitumor Activity.

Thioxanthones are bioisosteres of the naturally occurring xanthones. They have been described for multiple activities, including antitumor. As such, the synthesis of a library of thioxanthones was pursued, but unexpectedly, four tetracyclic thioxanthenes with a quinazoline-chromene scaffold were obtained. These compounds were studied for their human tumor cell growth inhibition activity, in the cell lines A375-C5, MCF-7 and NCI-H460. Photophysical studies were also performed. Two of the compounds displayed GI50 values below 10 µM for the three tested cell lines, and structure-activity relationship studies were established. Three compounds presented similar wavelengths of absorption and emission, characteristic of dyes with a push-pull character. The structures of two compounds were elucidated by X-ray crystallography. Two tetracyclic thioxanthenes emerged as hit compounds. One of the two compounds accumulated intracellularly as a bright fluorescent dye in the green channel, as analyzed by both fluorescence microscopy and flow cytometry, making it a promising theranostic cancer drug candidate.

Determination of the Absolute Configuration of Bioactive Indole-Containing Pyrazino[2,1-b]quinazoline-3,6-diones and Study of Their In Vitro Metabolic Profile.

In recent decades, fungi-derived naturally occurring quinazolines have emerged as potential drug candidates. Nevertheless, most studies are conducted for bioactivity assays, and little is known about their absorption, distribution, metabolism, and elimination (ADME) properties. To perform metabolic studies, the synthesis of the naturally occurring quinazolinone, fiscalin B (1), and its chloro derivative, 4-((1H-indol-3-yl)methyl)-8,10-dichloro-1-isobutyl-1,2-dihydro-6H-pyrazino[2,1-b]quinazoline-3,6(4H)-dione (2), disclosed as an antibacterial agent, was performed in a gram scale using a microwave-assisted polycondensation reaction with 22% and 17% yields, respectively. The structure of the non-natural (+)-fiscalin B was established, for the first time, by X-ray crystallography as (1R,4S)-1, and the absolute configuration of the naturally occurring fiscalin B (-)-1 was confirmed by comparison of its calculated and experimental electronic circular dichroism (ECD) spectra as (1S,4R)-1. in vitro metabolic studies were monitored for this class of natural products for the first time by ultra-high-performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS). The metabolic characteristics of 1 and 2 in human liver microsomes indicated hydration and hydroxylation mass changes introduced to the parent drugs.

New chiral stationary phases for liquid chromatography based on small molecules: Development, enantioresolution evaluation and chiral recognition mechanisms.

Recently, we reported the development of new chiral stationary phases (CSPs) for liquid chromatography (LC) based on chiral derivatives of xanthones (CDXs). Based on the most promising CDX selectors, 12 new CSPs were successfully prepared starting from suitable functionalized small molecules including xanthone and benzophenone derivatives. The chiral selectors comprising one, two, three, or four chiral moieties were covalently bonded to a chromatographic support and further packed into LC stainless-steel columns (150 × 2.1 mm I.D.). The enantioselective performance of the new CSPs was evaluated by LC using different classes of chiral compounds. Specificity for enantioseparation of some CDXs was observed in the evaluation of the new CSPs. Besides, assessment of chiral recognition mechanisms was performed by computational studies using molecular docking approach, which are in accordance with the chromatographic parameters. X-Ray analysis was used to establish a chiral selector 3D structure.

Repurposing Benzbromarone for Familial Amyloid Polyneuropathy: A New Transthyretin Tetramer Stabilizer.

Transthyretin (TTR) is a homotetrameric protein involved in human amyloidosis, including familial amyloid polyneuropathy (FAP). Discovering small-molecule stabilizers of the TTR tetramer is a therapeutic strategy for these diseases. Tafamidis, the only approved drug for FAP treatment, is not effective for all patients. Herein, we discovered that benzbromarone (BBM), a uricosuric drug, is an effective TTR stabilizer and inhibitor against TTR amyloid fibril formation. BBM rendered TTR more resistant to urea denaturation, similarly to iododiflunisal (IDIF), a very potent TTR stabilizer. BBM competes with thyroxine for binding in the TTR central channel, with an IC50 similar to IDIF and tafamidis. Results obtained by isothermal titration calorimetry (ITC) demonstrated that BBM binds TTR with an affinity similar to IDIF, tolcapone and tafamidis, confirming BBM as a potent binder of TTR. The crystal structure of the BBM-TTR complex shows two molecules binding deeply in the thyroxine binding channel, forming strong intermonomer hydrogen bonds and increasing the stability of the TTR tetramer. Finally, kinetic analysis of the ability of BBM to inhibit TTR fibrillogenesis at acidic pH and comparison with other stabilizers revealed that benzbromarone is a potent inhibitor of TTR amyloidogenesis, adding a new interesting scaffold for drug design of TTR stabilizers.

Synthesis of a Small Library of Nature-Inspired Xanthones and Study of Their Antimicrobial Activity.

A series of thirteen xanthones 3-15 was prepared based on substitutional (appendage) diversity reactions. The series was structurally characterized based on their spectral data and HRMS, and the structures of xanthone derivatives 1, 7, and 8 were determined by single-crystal X-ray diffraction. This series, along with an in-house series of aminated xanthones 16-33, was tested for in-vitro antimicrobial activity against seven bacterial (including two multidrug-resistant) strains and five fungal strains. 1-(Dibromomethyl)-3,4-dimethoxy-9H-xanthen-9-one (7) and 1-(dibromomethyl)-3,4,6-trimethoxy-9H-xanthen-9-one (8) exhibited antibacterial activity against all tested strains. In addition, 3,4-dihydroxy-1-methyl-9H-xanthen-9-one (3) revealed a potent inhibitory effect on the growth of dermatophyte clinical strains (T. rubrum FF5, M. canis FF1 and E. floccosum FF9), with a MIC of 16 µg/mL for all the tested strains. Compounds 3 and 26 showed a potent inhibitory effect on two C. albicans virulence factors: germ tube and biofilm formation.

Comparative genomics reveals a novel genetic organization of the sad cluster in the sulfonamide-degrader 'Candidatus Leucobacter sulfamidivorax' strain GP.

BACKGROUND: Microbial communities recurrently establish metabolic associations resulting in increased fitness and ability to perform complex tasks, such as xenobiotic degradation. In a previous study, we have described a sulfonamide-degrading consortium consisting of a novel low-abundant actinobacterium, named strain GP, and Achromobacter denitrificans PR1. However, we found that strain GP was unable to grow independently and could not be further purified. RESULTS: Previous studies suggested that strain GP might represent a new putative species within the Leucobacter genus (16S rRNA gene similarity < 97%). In this study, we found that average nucleotide identity (ANI) with other Leucobacter spp. ranged between 76.8 and 82.1%, further corroborating the affiliation of strain GP to a new provisional species. The average amino acid identity (AAI) and percentage of conserved genes (POCP) values were near the lower edge of the genus delimitation thresholds (65 and 55%, respectively). Phylogenetic analysis of core genes between strain GP and Leucobacter spp. corroborated these findings. Comparative genomic analysis indicates that strain GP may have lost genes related to tetrapyrrole biosynthesis and thiol transporters, both crucial for the correct assembly of cytochromes and aerobic growth. However, supplying exogenous heme and catalase was insufficient to abolish the dependent phenotype. The actinobacterium harbors at least two copies of a novel genetic element containing a sulfonamide monooxygenase (sadA) flanked by a single IS1380 family transposase. Additionally, two homologs of sadB (4-aminophenol monooxygenase) were identified in the metagenome-assembled draft genome of strain GP, but these were not located in the vicinity of sadA nor of mobile or integrative elements. CONCLUSIONS: Comparative genomics of the genus Leucobacter suggested the absence of some genes encoding for important metabolic traits in strain GP. Nevertheless, although media and culture conditions were tailored to supply its potential metabolic needs, these conditions were insufficient to isolate the PR1-dependent actinobacterium further. This study gives important insights regarding strain GP metabolism; however, gene expression and functional studies are necessary to characterize and further isolate strain GP. Based on our data, we propose to classify strain GP in a provisional new species within the genus Leucobacter, 'Candidatus Leucobacter sulfamidivorax'.

Erubescensoic Acid, a New Polyketide and a Xanthonopyrone SPF-3059-26 from the Culture of the Marine Sponge-Associated Fungus Penicillium erubescens KUFA 0220 and Antibacterial Activity Evaluation of Some of Its Constituents.

A new polyketide erubescensoic acid (1), and the previously reported xanthonopyrone, SPF-3059-26 (2), were isolated from the uninvestigated fractions of the ethyl acetate crude extract of the marine sponge-associated fungus Penicillium erubescens KUFA0220. The structures of the new compound, erubescensoic acid (1), and the previously reported SPF-3059-26 (2), were elucidated by extensive analysis of 1D and 2D-NMR spectra as well as HRMS. The absolute configuration of the stereogenic carbon of erubescensoic acid (1) was determined by X-ray analysis. Erubescensoic acid (1) and SPF-3059-26 (2), together with erubescenschromone B (3), penialidin D (4), and 7-hydroxy-6-methoxy-4-oxo-3-[(1E)-3-oxobut-1-en-1-yl]-4H-chromen-5-carboxylic acid (5), recently isolated from this fungus, were assayed for their antibacterial activity against gram-positive and gram-negative reference strains and the multidrug-resistant (MDR) strains from the environment. The capacity of these compounds to interfere with the bacterial biofilm formation and their potential synergism with clinically relevant antibiotics for the MDR strains were also investigated.

Chromone Derivatives and Other Constituents from Cultures of the Marine Sponge-Associated Fungus Penicillium erubescens KUFA0220 and Their Antibacterial Activity.

A previously unreported chromene derivative, 1-hydroxy-12-methoxycitromycin (1c), and four previously undescribed chromone derivatives, including pyanochromone (3b), spirofuranochromone (4), 7-hydroxy-6-methoxy-4-oxo-3-[(1E)-3-oxobut-1-en-1-yl]-4H-chromene-5-carboxylic acid (5), a pyranochromone dimer (6) were isolated, together with thirteen known compounds: ß-sitostenone, ergosterol 5,8-endoperoxide, citromycin (1a), 12-methoxycitromycin (1b), myxotrichin D (1d), 12-methoxycitromycetin (1e), anhydrofulvic acid (2a), myxotrichin C (2b), penialidin D (2c), penialidin F (3a), SPF-3059-30 (7), GKK1032B (8) and secalonic acid A (9), from cultures of the marine sponge- associated fungus Penicillium erubescens KUFA0220. Compounds 1a⁻e, 2a, 3a, 4, 7⁻9, were tested for their antibacterial activity against Gram-positive and Gram-negative reference and multidrug-resistant strains isolated from the environment. Only 8 exhibited an in vitro growth inhibition of all Gram-positive bacteria whereas 9 showed growth inhibition of methicillin-resistant Staphyllococus aureus (MRSA). None of the compounds were active against Gram-negative bacteria tested.

Bis-Indolyl Benzenoids, Hydroxypyrrolidine Derivatives and Other Constituents from Cultures of the Marine Sponge-Associated Fungus Aspergillus candidus KUFA0062.

A previously unreported bis-indolyl benzenoid, candidusin D (2e) and a new hydroxypyrrolidine alkaloid, preussin C (5b) were isolated together with fourteen previously described compounds: palmitic acid, clionasterol, ergosterol 5,8-endoperoxides, chrysophanic acid (1a), emodin (1b), six bis-indolyl benzenoids including asterriquinol D dimethyl ether (2a), petromurin C (2b), kumbicin B (2c), kumbicin A (2d), 2″-oxoasterriquinol D methyl ether (3), kumbicin D (4), the hydroxypyrrolidine alkaloid preussin (5a), (3S, 6S)-3,6-dibenzylpiperazine-2,5-dione (6) and 4-(acetylamino) benzoic acid (7), from the cultures of the marine sponge-associated fungus Aspergillus candidus KUFA 0062. Compounds 1a, 2a-e, 3, 4, 5a-b, and 6 were tested for their antibacterial activity against Gram-positive and Gram-negative reference and multidrug-resistant strains isolated from the environment. Only 5a exhibited an inhibitory effect against S. aureus ATCC 29213 and E. faecalis ATCC29212 as well as both methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE) strains. Both 1a and 5a also reduced significant biofilm formation in E. coli ATCC 25922. Moreover, 2b and 5a revealed a synergistic effect with oxacillin against MRSA S. aureus 66/1 while 5a exhibited a strong synergistic effect with the antibiotic colistin against E. coli 1410/1. Compound 1a, 2a-e, 3, 4, 5a-b, and 6 were also tested, together with the crude extract, for cytotoxic effect against eight cancer cell lines: HepG2, HT29, HCT116, A549, A 375, MCF-7, U-251, and T98G. Except for 1a, 2a, 2d, 4, and 6, all the compounds showed cytotoxicity against all the cancer cell lines tested.

A New Dihydrochromone Dimer and Other Secondary Metabolites from Cultures of the Marine Sponge-Associated Fungi Neosartorya fennelliae KUFA 0811 and Neosartorya tsunodae KUFC 9213.

A previously unreported dihydrochromone dimer, paecilin E (1), was isolated, together with eleven known compounds: ß-sitostenone, ergosta-4,6,8 (14), 22-tetraen-3-one, cyathisterone, byssochlamic acid, dehydromevalonic acid lactone, chevalone B, aszonalenin, dankasterone A (2), helvolic acid, secalonic acid A and fellutanine A, from the culture filtrate extract of the marine sponge-associated fungus Neosartorya fennelliae KUFA 0811. Nine previously reported metabolites, including a chromanol derivative (3), (3ß, 5α, 22E), 3,5-dihydroxyergosta-7,22-dien-6-one (4), byssochlamic acid, hopan-3ß,22-diol, chevalone C, sartorypyrone B, helvolic acid, lumichrome and the alkaloid harmane were isolated from the culture of the marine-sponge associated fungus Neosartorya tsunodae KUFC 9213. Paecilin E (1), dankasterone A (2), a chromanol derivative (3), (3ß, 5α, 22E)-3,5-dihydroxyergosta-7,22-dien-6-one (4), hopan-3ß,22-diol (5), lumichrome (6), and harmane (7) were tested for their antibacterial activity against Gram-positive and Gram-negative reference and multidrug-resistant strains isolated from the environment. While paecilin E (1) was active against S. aureus ATCC 29213 and E. faecalis ATCC 29212, dankastetrone A (2) was only effective against E. faecalis ATCC 29212 and the multidrug-resistant VRE E. faecalis A5/102. Both compounds neither inhibit biofilm mass production in any of the strains at the concentrations tested nor exhibit synergistic association with antibiotics.

A New Ergosterol Analog, a New Bis-Anthraquinone and Anti-Obesity Activity of Anthraquinones from the Marine Sponge-Associated Fungus Talaromyces stipitatus KUFA 0207.

A new ergosterol analog, talarosterone (1) and a new bis-anthraquinone derivative (3) were isolated, together with ten known compounds including palmitic acid, ergosta-4,6,8(14),22-tetraen-3-one, ergosterol-5,8-endoperoxide, cyathisterone (2), emodin (4a), questinol (4b), citreorosein (4c), fallacinol (4d), rheoemodin (4e) and secalonic acid A (5), from the ethyl acetate extract of the culture of the marine sponge-associated fungus Talaromyces stipitatus KUFA 0207. The structures of the new compounds were established based on extensive 1D and 2D spectral analysis, and in the case of talarosterone (1), the absolute configurations of its stereogenic carbons were determined by X-ray crystallographic analysis. The structure and stereochemistry of cyathisterone (2) was also confirmed by X-ray analysis. The anthraquinones 4a-e and secalonic acid A (5) were tested for their anti-obesity activity using the zebrafish Nile red assay. Only citreorosein (4c) and questinol (4b) exhibited significant anti-obesity activity, while emodin (4a) and secalonic acid A (5) caused toxicity (death) for all exposed zebrafish larvae after 24 h.

Secondary Metabolites from the Culture of the Marine Sponge-Associated Fungi Talaromyces tratensis and Sporidesmium circinophorum.

Wortmin (1), meso-1,4-bis(4-methoxybenzyl)-2,3-butanediol (2), and a new isocoumarin derivative tratenopyrone (3) were isolated from the marine sponge-associated fungus Talaromyces tratensis KUFA 0091. A new diphenyl ether derivative, circinophoric acid (4), was isolated, together with the previously reported anthraquinones catenarin and physcion, the benzophenone monomethylsoluchrin, and ß-ergosterol-5,8-endoperoxide, from the marine sponge-associated fungus Sporidesmium circinophorum KUFA 0043. The structures of the new compounds were established based on an extensive analysis of 1D and 2D NMR spectra, and, in the case of compounds 2-4, also by X-ray analysis. All of the isolated compounds were tested for their antibacterial activity against Gram-positive and Gram-negative bacteria, and multidrug-resistant isolates from the environment, as well as for their anti-quorum sensing based on the pigment production of Chromobacterium violaceum ATCC 31523. None of the compounds exhibited either antibacterial (MIC > 256 µg/mL) or anti-quorum sensing activities. The compounds were also inactive in the antifungal (MIC > 512 µg/mL) and cancer cell line (GI50 > 150 µM) assays.