Bioassay-Guided Fractionation Leads to the Detection of Cholic Acid Generated by the Rare Thalassomonas sp.

Bacterial symbionts of marine invertebrates are rich sources of novel, pharmaceutically relevant natural products that could become leads in combatting multidrug-resistant pathogens and treating disease. In this study, the bioactive potential of the marine invertebrate symbiont Thalassomonas actiniarum was investigated. Bioactivity screening of the strain revealed Gram-positive specific antibacterial activity as well as cytotoxic activity against a human melanoma cell line (A2058). The dereplication of the active fraction using HPLC-MS led to the isolation and structural elucidation of cholic acid and 3-oxo cholic acid. T. actiniarum is one of three type species belonging to the genus Thalassomonas. The ability to generate cholic acid was assessed for all three species using thin-layer chromatography and was confirmed by LC-MS. The re-sequencing of all three Thalassomonas type species using long-read Oxford Nanopore Technology (ONT) and Illumina data produced complete genomes, enabling the bioinformatic assessment of the ability of the strains to produce cholic acid. Although a complete biosynthetic pathway for cholic acid synthesis in this genus could not be determined based on sequence-based homology searches, the identification of putative penicillin or homoserine lactone acylases in all three species suggests a mechanism for the hydrolysis of conjugated bile acids present in the growth medium, resulting in the generation of cholic acid and 3-oxo cholic acid. With little known currently about the bioactivities of this genus, this study serves as the foundation for future investigations into their bioactive potential as well as the potential ecological role of bile acid transformation, sterol modification and quorum quenching by Thalassomonas sp. in the marine environment

Qualitative and Quantitative Comparison of Liquid–Liquid Phase Extraction Using Ethyl Acetate and Liquid–Solid Phase Extraction Using Poly-Benzyl-Resin for Natural Products

A key step in the process of isolating microbial natural products is the preparation of an extract from a culture. This step determines which molecules will be available for detection in the subsequent chemical and biological analysis of a biodiscovery pipeline. In the present study we wanted to document potential differences in performance between liquid–liquid extraction using ethyl acetate and liquid–solid extraction using a poly‐benzyl‐resin. For the comparison of the two extraction protocols, we spiked a culture of Flavobacterium sp. with a diverse selection of natural products of microbial and plant origin to investigate whether the methods were comparable with respect to selectivity. We also investigated the efficiency of the two extraction methods quantita‐ tively, using water spiked with a selection of natural products, and studied the quantitative effect of different pH levels of the aqueous solutions on the extraction yields of the two methods. The same compounds were extracted by the two methods, but the solid‐phase extract contained more media components compared with the liquid‐phase extract. Quantitatively, the two extraction methods varied in their recovery rates. We conclude that practical aspects could be more important when selecting one of the extraction protocols, as their efficiencies in extracting specific compounds were quite similar

Large onychites (cephalopod hooks) from the Upper Jurassic of the Boreal Realm

We report on the discovery of large cephalopod arm hooks (mega−onychites) from the Kimmeridgian and Volgian of Spitsbergen (Agardhfjellet Formation). This includes a largely uncompressed hook in a seep carbonate, with preservation of surface sculpture. We suggest the use of logarithmic spirals as morphological descriptors for the outer part of cephalopod arm hooks, with implications for systematics and functional morphology. Comparison with Upper Jurassic material from Greenland, northern Norway and the North Sea demonstrates a remarkably consistent morphology, which we assign to the same form species, Onychites quenstedti. Considering the relatively small stratigraphic (Kimmeridgian–Volgian) and biogeographic (Boreal) range of this large form, it is likely that it represents a single biological species or genus

Selective isolation of Arctic marine actinobacteria and a down-scaled fermentation and extraction strategy for identifying bioactive compounds

Actinobacteria are among the most prolific producers of bioactive secondary metabolites. In order to collect Arctic marine bacteria for the discovery of new bioactive metabolites, actinobacteria were selectively isolated during a research cruise in the Greenland Sea, Norwegian Sea and the Barents Sea. In the frame of the isolation campaign, it was investigated how different sample treatments, isolation media and sample-sources, such as animals and sediments, affected the yield of actinobacterial isolates to aid further isolation campaigns. Special attention was given to sediments, where we expected spores of spore forming bacteria to enrich. Beside actinobacteria a high share of bacilli was obtained which was not desired. An experimental protocol for down-scaled cultivation and extraction was tested and compared with an established low-throughput cultivation and extraction protocol. The heat-shock method proved suitable to enrich spore-, or endospore forming bacteria such as bacilli. Finally, a group bioactive compounds could be tentatively identified using UHPLC–MS/MS analysis of the active fractions.publishedVersio

Lulworthinone, a New Dimeric Naphthopyrone From a Marine Fungus in the Family Lulworthiaceae With Antibacterial Activity Against Clinical Methicillin-Resistant Staphylococcus aureus Isolates

The emergence of drug-resistant bacteria is increasing rapidly in all parts of the world, and the need for new antibiotics is urgent. In our continuous search for new antimicrobial molecules from under-investigated Arctic marine microorganisms, a marine fungus belonging to the family Lulworthiaceae (Lulworthiales, Sordariomycetes, and Ascomycota) was studied. The fungus was isolated from driftwood, cultivated in liquid medium, and studied for its potential for producing antibacterial compounds. Through bioactivity-guided isolation, a novel sulfated biarylic naphtho-α-pyrone dimer was isolated, and its structure was elucidated by spectroscopic methods, including 1D and 2D NMR and HRMS. The compound, named lulworthinone (1), showed antibacterial activity against reference strains of Staphylococcus aureus and Streptococcus agalactiae, as well as several clinical MRSA isolates with MICs in the 1.56–6.25 μg/ml range. The compound also had antiproliferative activity against human melanoma, hepatocellular carcinoma, and non-malignant lung fibroblast cell lines, with IC50 values of 15.5, 27, and 32 μg/ml, respectively. Inhibition of bacterial biofilm formation was observed, but no eradication of established biofilm could be detected. No antifungal activity was observed against Candida albicans. During the isolation of 1, the compound was observed to convert into a structural isomer, 2, under acidic conditions. As 1 and 2 have high structural similarity, NMR data acquired for 2 were used to aid in the structure elucidation of 1. To the best of our knowledge, lulworthinone (1) represents the first new bioactive secondary metabolite isolated from the marine fungal order Lulworthiales

Fluctuation and change of serum urate levels and flares in gout: results from the NOR-Gout study

A gout attack may evolve after a purine-rich diet or alcohol and after starting urate-lowering therapy (ULT). The relationships between fluctuation and change in serum urate (SU) with the occurrence of flares were investigated in this study. In the prospective NOR-Gout study, gout patients with increased SU and a recent flare were treated to target with ULT over 1 year, with follow-up at year 2 with SU and flare as outcomes. SU and flares were assessed at both monthly and 3-monthly intervals until target SU was reached. Fluctuation over periods and changes in SU between two time points were assessed and compared in patients with and without flares. At year 1, 186 patients completed follow-up (88.2%) and 173 (82.0%) at year 2. Mean age (SD) at baseline was 56.4 (13.7) years, disease duration was 7.8 (7.6) years, and 95.3% were men. The first-year SU fluctuation and change were related to flare occurrence during year 1 (both p 360 mu mol/l were not related to flares. Fluctuation and change in SU were related to flare occurrence during the first year of ULT, while changes between visits and reaching SU levels > 360 mu mol/L were not related to flares.Open access funding provided by University of Oslo (incl Oslo University Hospital)

Two Novel Lyso-Ornithine Lipids Isolated from an Arctic Marine Lacinutrix sp. Bacterium

The Lacinutrix genus was discovered in 2005 and includes 12 Gram-negative bacterial species. To the best of our knowledge, the secondary metabolite production potential of this genus has not been explored before, and examination of Lacinutrix species may reveal novel chemistry. As part of a screening project of Arctic marine bacteria, the Lacinutrix sp. strain M09B143 was cultivated, extracted, fractionated and tested for antibacterial and cytotoxic activities. One fraction had antibacterial activity and was subjected to mass spectrometry analysis, which revealed two compounds with elemental composition that did not match any known compounds in databases. This resulted in the identification and isolation of two novel isobranched lyso-ornithine lipids, whose structures were elucidated by mass spectrometry and NMR spectroscopy. Lyso-ornithine lipids consist of a 3-hydroxy fatty acid linked to the alpha amino group of an ornithine amino acid through an amide bond. The fatty acid chains were determined to be iso-C15:0 (1) and iso-C16:0 (2). Compound 1 was active against the Gram-positive S. agalactiae, while 2 showed cytotoxic activity against A2058 human melanoma cells

Antimicrobial Activity of Securamines From the Bryozoan Securiflustra securifrons

Natural products and their derivatives have served as powerful therapeutics against pathogenic microorganisms and are the mainstay of our currently available treatment options to combat infections. As part of our ongoing search for antimicrobial natural products from marine organisms, one fraction prepared from the Arctic marine bryozoan Securiflustra securifrons was found to be active against the human pathogenic bacterium Streptococcus agalactiae (gr. B). Chemical investigation of the fraction revealed that it contained several variants of the highly modified secondary metabolites known as securamines. The securamines are alkaloids sharing a common isoprene-histamine-tryptamine backbone. In this study, we describe the antimicrobial activities of securamine C, E, and H – J (4, 5, and 1-3) and the attempt to deconvolute the mode of action of 1

One- and 2-year flare rates after treat-to-target and tight-control therapy of gout: results from the NOR-Gout study

[EN] OBJECTIVES: To explore the frequency and predictors of flares over 2years during a treat-to-target strategy with urate-lowering therapy (ULT) in patients with gout. METHODS: In the treat-to-target, tight control NOR-Gout study patients started ULT with escalating doses of allopurinol. Flares were recorded over 2years. Baseline predictors of flares during months 9-12 in year 1 and during year 2 were analyzed by multivariable logistic regression. RESULTS: Of 211 patients included (mean age 56.4years, disease duration 7.8years, 95% males), 81% (150/186) of patients experienced at least one gout flare during the first year and 26% (45/173) during the second year. The highest frequency of flares in the first year was seen during months 3-6 (46.8% of patients). Baseline crystal depositions detected by ultrasound and by dual-energy computed tomography (DECT) were the only variables which predicted flares both during the first period of interest at months 9-12 (OR 1.033; 95% CI 1.010-1.057, and OR 1.056; 95% CI 1.007-1.108) and also in year 2. Baseline subcutaneous tophi (OR 2.42, 95% CI 1.50-5.59) and prior use of colchicine at baseline (OR 2.48, 95% CI 1.28-4.79) were independent predictors of flares during months 9-12, whereas self-efficacy for pain was a protective predictor (OR 0.98 per unit, 95% CI 0.964-0.996). CONCLUSIONS: In patients with gout, flares remain frequent during the first year of a treat-to-target ULT strategy, especially during months 3-6, but are much less frequent during year 2. Baseline crystal depositions predict flares over 2years, supporting ULT early during disease course.The study was funded by Diakonhjemmet Hospital and was performed by employees at National Advisory Unit on Rehabilitation in Rheumatology (NKRR) and Division of Rheumatology and Research, Diakonhjemmet Hospital, Oslo, Norway