Identification of microbial metabolites that accelerate the ubiquitin-dependent degradation of c-Myc.

Myc belongs to a family of proto-oncogenes that encode transcription factors. The overexpression of c-Myc causes many types of cancers. Recently, we established a system for screening c-Myc inhibitors and identified antimycin A by screening the RIKEN NPDepo chemical library. The specific mechanism of promoting tumor cell metastasis by high c-Myc expression remains to be explained. In this study, we screened approximately 5,600 microbial extracts using this system and identified a broth prepared from Streptomyces sp. RK19-A0402 strongly inhibits c-Myc transcriptional activity. After purification of the hit broth, we identified compounds closely related to the aglycone of cytovaricin and had a structure similar to that of oligomycin A. Similar to oligomycin A, the hit compounds inhibited mitochondrial complex V. The mitochondria dysfunction caused by the compounds induced the production of reactive oxygen species (ROS), and the ROS activated GSK3α/ß that phosphorylated c-Myc for ubiquitination. This study provides a successful screening strategy for identifying natural products as potential c-Myc inhibitors as potential anticancer agents.

cis-Decalin-containing tetramic acids as inhibitors of insect steroidogenic glutathione S-transferase Noppera-bo.

Decalin-containing tetramic acid is a bioactive scaffold primarily produced by filamentous fungi. The structural diversity of this group of compounds is generated by characteristic enzymes of fungal biosynthetic pathways, including polyketide synthase/nonribosomal peptide synthetase hybrid enzymes and decalin synthase, which are responsible for the construction of a linear polyenoyl tetramic acid structure and stereoselective decalin formation via the intramolecular Diels-Alder reaction, respectively. Compounds that differed only in the decalin configuration were collected from genetically engineered mutants derived from decalin-containing tetramic acid-producing fungi and used for a structure-activity relationship study. Our evaluation of biological activities, such as cytotoxicity against several cancer cell lines and antibacterial, antifungal, antimalarial, and mitochondrial inhibitory activities, demonstrated that the activity for each assay varies depending on the decalin configurations. In addition to these known biological activities, we revealed that the compounds showed inhibitory activity against the insect steroidogenic glutathione S-transferase Noppera-bo. Engineering the decalin configurations would be useful not only to find derivatives with better biological activities but also to discover overlooked biological activities.

Wakodecaline C, new tetrahydrofuran-fused decalin metabolite isolated from fungus Pyrenochaetopsis sp. RK10-F058.

A new decalin-containing secondary metabolite, wakodecaline C, was isolated from a fungus Pyrenochaetopsis sp. RK10-F058 by screening structurally interesting metabolites based on LC/MS profiling. The structure including the absolute configuration was determined by a combination of spectroscopic methods including NMR and mass spectrometry, chemical reaction, and calculation of ECD spectra. Wakodecaline C has unique structural features containing a tetrahydrofuran-fused decalin skeleton and tetramic acid moiety, which are connected through a double bond. The compound showed moderate cytotoxicity against HL-60 cells and antimalarial activity against the Plasmodium falciparum 3D7 strain.

Naturally Occurring 8ß,13ß-kaur-15-en-17-al and Anti-Malarial Activity from Podocarpus polystachyus Leaves.

Despite much interest and studies toward the genus Podocarpus, the anti-malarial evaluation of Podocarpus polystachyus's phytoconstituents remains lacking. Herein, the phytoconstituents of P. polystachyus leaves and their anti-malarial effect against Plasmodium falciparum were investigated for the first time. One new natural product, 8ß,13ß-kaur-15-en-17-al (1), along with three known compounds, 8ß,13ß-kaur-15-en-17-ol (2) and 13ß-kaur-16-ene (3), and α-tocopherol hydroquinone (4) were isolated via HR-ESI-MS and NMR analyses. Compounds 1 and 2 inhibited P. falciparum growth at 12 and 52 µM of IC50, respectively. Their anti-malarial activity was associated with the in silico P. falciparum lactate dehydrogenase (PfLDH) inhibition. Molecular docking of ligands 1 and 2 with the putative target PfLDH revealed ~-2 kcal/mol of binding energies more negative than the control. Molecular dynamic simulations (100 ns) showed equal or smaller deviation values (RMSD, RMSF, Rg) and stronger interactions of PfLDH-1 and PfLDH-2 complexes via at least one consistent H-bond than the control. Additionally, a slightly increased PfLDH H-bond profile in their interactions improved the PfLDH dynamic and structural stabilities. Overall, this study supports the relevance of 1 and 2 as plasmodial growth inhibitors with their putative anti-PfLDH activity, which could be a potential scaffold for developing anti-malarial drugs.

Identification of a Small-Molecule Glucose Transporter Inhibitor, Glutipyran, That Inhibits Cancer Cell Growth.

Cancer cells reprogram their metabolism to survive and grow. Small-molecule inhibitors targeting cancer are useful for studying its metabolic pathways and functions and for developing anticancer drugs. Here, we discovered that glutipyran and its derivatives inhibit glycolytic activity and cell growth in human pancreatic cancer cells. According to proteomic profiling of glutipyran-treated cells using our ChemProteoBase, glutipyran was clustered within the group of endoplasmic reticulum (ER) stress inducers that included glycolysis inhibitors. Glutipyran inhibited glucose uptake and suppressed the growth of various cancer cells, including A431 cells that express glucose transporter class I (GLUT1) and DLD-1 GLUT1 knockout cells. When cotreated with the mitochondrial respiration inhibitor metformin, glutipyran exhibited a synergistic antiproliferative effect. Metabolome analysis revealed that glutipyran markedly decreased most metabolites of the glycolytic pathway and the pentose phosphate pathway. Glutipyran significantly suppressed tumor growth in a xenograft mouse model of pancreatic cancer. These results suggest that glutipyran acts as a broad-spectrum GLUT inhibitor and reduces cancer cell growth.

Zealpeptaibolin, an 11-mer cytotoxic peptaibol group with 3 Aib-Pro motifs isolated from Trichoderma sp. RK10-F026.

Six new 11-mer peptaibols designed as zealpeptaibolins, A - F were isolated from the soil fungus, Trichoderma sp. RK10-F026, based on the principal component analysis of the MS data from five different culture compositions. Previously, 20-mer peptaibols from the same fungal strain were identified; 11-mer peptaibols in contrast were discovered from a different culture condition, signifying peptaibol production was culture condition-dependent. These peptaibols contained three Aib-Pro motifs in the sequence. The structures were established by NMR and HR-MS experiments including detailed MS/MS fragmentations. The absolute configurations were determined by Marfey's analysis. Zealpeptaibolin F exhibited the strongest cytotoxicity toward K562 leukemia cells with an IC50 value of 0.91 µM.

A new peptaibol, RK-026A, from the soil fungus Trichoderma sp. RK10-F026 by culture condition-dependent screening.

A new peptaibol, RK-026A (1) was isolated from a fungus, Trichoderma sp. RK10-F026, along with atroviridin B (2), alamethicin II (3), and polysporin B (4) as a cytotoxic compound, which was selected by principal component analysis of the MS data from 5 different culture conditions. The structure of 1 was determined as a new atroviridin B derivative containing Glu at the 18th residue instead of Gln by NMR and HR-MS analyses including the investigation of detailed MS/MS fragmentations. 1 showed cytotoxicity toward K562 leukemia cells at an IC50 value of 4.1 µm.

Heterologous Expression of the Biosynthetic Gene Cluster for Verticilactam and Identification of Analogues.

Verticilactam and the new geometric isomers, verticilactams B and C, were produced by heterologous expression of the biosynthetic gene cluster for verticilactam using the Streptomyces avermitilis SUKA17 strain. Only verticilactam, a compound with a characteristic ß-ketoamide unit within a 16-membered polyketide macrolactam conjugated with an octalin skeleton, had been previously reported having been isolated from Streptomyces spiroverticillatus JC-8444. In this report, minor verticilactam derivatives were isolated from the transformed strain, and their structures elucidated by spectral analysis. Verticilactam B was a geometric isomer at Δ17 and Δ19, and verticilactam C was the Δ19 and Δ21 isomer. In addition, the absolute configuration of verticilactam was confirmed by ECD analysis and NMR chemical shifts. The stereochemistry assignments of the hydroxy groups at C-10 and C-12 were supported by the domain organization of the polyketide synthase identified in the verticilactam gene cluster. Verticilactam showed moderate activity against the malaria parasite Plasmodium falciparum 3D7 strain with no significant cytotoxicity or antimicrobial effects.

Structure and biological activity of Metarhizin C, a stereoisomer of BR-050 from Tolypocladium album RK17-F0007.

Metarhizin C, a stereoisomer of BR-050 was isolated from a fungus Tolypocladium album RK17-F0007 through a screening program to search for new antitumor compounds. A structure of the isomer was determined by spectroscopic methods including detailed analysis of NOESY correlation and mass spectrometry, and found to be identical to that of 3-desacylmetarhizin A with the absolute structure. Previously, it had been isolated by Kikuchi et al and proposed as BR-050 including the stereo-structure. However, detailed analysis for the newly isolated isomer confirmed that 3-desacylmetarhizin A was not identical to BR-050. Therefore, we assigned it metarhizin C as a new BR-050 isomer. Metarhizin C showed selective cytotoxicity against osteosarcoma MG-63 cells in a glucose independent condition with IC50 value of 0.79 µg/ml, while > 30 µg/ml of IC50 value in a normal condition, and inhibited a mitochondrial respiration.

Construction of a potato fraction library for the investigation of functional secondary metabolites.

A potato fraction library was constructed to investigate functional secondary metabolites from 8 cultivars: Kitahime, Pilka, Sakurafubuki, Atlantic, Toyoshiro, Snowden, Kitamurasaki, and Northern Ruby, which were divided into flower, leaf, stem, roots, tuber peel, and tuber. Each fraction was a semi-purified extract and about 800 fractions were prepared for the library. They were analyzed by DAD-LC/MS to obtain structural information and were evaluated for various biological activities. LC/MS data showed that each part had a specific characteristic for their constituents supported by principal component analysis (PCA). Approximately 40% of fractions showed significant biological activities at 30 µg/mL, especially the flower fractions showed strong cytotoxicity. PCAs based on the activity and LC/MS data suggested that the strong cytotoxicity of flowers was derived from a complex mixture of potato glycoalkaloids. In addition, tuber peel fractions showed strong antimalarial activity, which had not been reported before. Also, some fractions showed significant antibacterial activities.

Bolus 5-fluorouracil (5-FU) In Combination With Oxaliplatin Is Safe and Well Tolerated in Patients Who Experienced Coronary Vasospasm With Infusional 5-FU or Capecitabine.

INTRODUCTION: Coronary vasospasm associated with fluoropyrimidine (FP)-based chemotherapy is a potentially serious complication and reported to occur more often with infusional 5-fluorouracil (5-FU) or capecitabine than with bolus 5-FU. Given the additional benefit of oxaliplatin over FP alone in the management of colorectal cancer, retaining oxaliplatin in the treatment regimen is desirable, but the safety of combining bolus 5-FU with oxaliplatin in patients with FP-induced vasospasm is not well established. We performed a retrospective review to explore the safety of substituting FLOX (bolus 5-FU, oxaliplatin, leucovorin) for FOLFOX (infusional 5-FU, oxaliplatin, leucovorin) and CAPOX (capecitabine, oxaliplatin) in patients who had FP-induced coronary vasospasm. PATIENTS AND METHODS: The pharmacy database of Mayo Clinic was queried to identify patients who developed coronary vasospasm associated with FOLFOX or CAPOX between January 2011 and January 2018 and were subsequently treated with FLOX. Detailed information was obtained on these patients by retrospective electronic chart review. RESULTS: A total of 10 patients (median age, 56.5 years; range, 36-77 years) were identified, 9 with FOLFOX and 1 with CAPOX. Among the patients treated with FOLFOX, 8 patients had chest pain as the presenting complaint that had started within 48 hours of beginning of the 5-FU infusion. In 9 of 10 patients, coronary vasospasm occurred with the first cycle of therapy. All patients made full recovery after discontinuation of infusional 5-FU or capecitabine. All patients subsequently received FLOX with 7 median bolus 5-FU doses (range, 2-22 doses) and 7 median oxaliplatin doses (range, 2-12 doses) at 7 days to 18 months after the event, with 7 patients treated within 4 weeks of the event. FLOX did not cause any cardiovascular adverse events in any of the 10 patients. CONCLUSION: Bolus 5-FU in combination with oxaliplatin is safe in patients who have experienced coronary vasospasm with infusional 5-FU or capecitabine.

Wakodecalines A and B, new decaline metabolites isolated from a fungus Pyrenochaetopsis sp. RK10-F058.

Two new decaline metabolites, wakodecalines A and B, were isolated from a fungus, Pyrenochaetopsis sp. RK10-F058, by screening for structurally unique metabolites using LC/MS analysis. Their structures were determined on the basis of NMR and mass spectrometric measurements. The absolute structures were confirmed by a combination of chemical methods including chemical degradation, a modified Mosher's method and Marfey's method, and comparison of the experimental electronic CD (ECD) spectrum with calculated one. Both compounds had a cyclopentanone-fused decaline skeleton and an N-methylated amino acid moiety derived from a serine. They showed moderate antimalarial activity against the Plasmodium falciparum 3D7 strain.The Journal of Antibiotics advance online publication, 13 September 2017; doi:10.1038/ja.2017.103.

Prevention of Subsequent Catheter-Related Bloodstream Infection Using Catheter Locks in High-Risk Patients Receiving Home Parenteral Nutrition.

INTRODUCTION: Catheter-related bloodstream infection (CRBSI) is a serious complication in patients receiving home parenteral nutrition (HPN). Antibiotic lock therapy (ALT) and ethanol lock therapy (ELT) can be used to prevent CRBSI episodes in high-risk patients. METHODS: Following institutional review board approval, all patients enrolled in the Mayo Clinic HPN program from January 1, 2006, to December 31, 2013, with catheter locking were eligible to be included. Patients without research authorization and <18 years old at the initiation of HPN were excluded. Total number of infections before and after ALT or ELT were estimated in all patients. RESULTS: A total of 63 patients were enrolled during the study period. Of 59 eligible patients, 29 (49%) were female, and 30 (51%) were male. The median duration of HPN was 3.66 (interquartile range, 0.75-8.19) years. The mean age ± SD at initiation of HPN was 49.89 ± 14.07 years. A total of 51 patients were instilled with ALT, and 8 patients were instilled with ELT during their course of HPN. A total of 313 CRBSI episodes occurred in these patients, 264 before locking and 49 after locking ( P < .001). Rate of infection per 1000 catheter days was 10.97 ± 25.92 before locking and 1.09 ± 2.53 after locking ( P < .001). DISCUSSION: The major findings of the present study reveal that ALT or ELT can reduce the overall rate of infections per 1000 catheter days. ALT or ELT can be used in appropriate clinical setting for patients receiving HPN.

Hyperglycemia During Home Parenteral Nutrition Administration in Patients Without Diabetes.

BACKGROUND: Parenteral nutrition (PN) is a life-sustaining therapy in appropriate clinical settings. In the hospital setting, some nondiabetic patients develop hyperglycemia and subsequently require long-term insulin while receiving PN. Whether similar hyperglycemia is seen in the outpatient setting is unclear. METHODS: We studied patients enrolled in the Mayo Clinic Home Parenteral Nutrition (HPN) program between January 1, 2010, and December 31, 2012. Patients were excluded if they had diabetes mellitus type 2 (DM2), had previously received HPN, had taken corticosteroids, or were at risk for refeeding syndrome. RESULTS: Of 144 enrolled patients, 93 met inclusion criteria with 39 patients requiring the addition of insulin to HPN. The mean age of the insulin-requiring group (IR) was higher than that of the non-insulin-requiring group (NIR) (60.74 ± 13.62 years vs 48.97 ± 17.62 years, P < .001). There were 17 (44%) men in the IR group and 26 (48%) men in the NIR group. Mean blood glucose at baseline before starting the infusion was 131.82 ± 49.55 mg/dL in IR patients and 106.16 ± 59.01 mg/dL in NIR patients ( P = .03). In the stepwise multivariate analysis for assessing the risk for developing hyperglycemia, HR for age was 1.020 (1.010-1.031), P < .001. CONCLUSIONS: Hyperglycemia is a common finding with the use of PN in both the hospital and ambulatory setting in patients without a previous diagnosis of DM2. Age was the most significant predictor of the requirement of insulin in the present study. When hyperglycemia is managed appropriately with insulin therapy, the long-term complications can be minimized.

Catheter Salvage After Catheter-Related Bloodstream Infection During Home Parenteral Nutrition.

BACKGROUND: Catheter-related bloodstream infection (CRBSI) is a common complication in patients receiving home parenteral nutrition (HPN). Data regarding catheter salvage after a CRBSI episode are limited. We aimed to determine the incidence of CRBSI and rates of catheter salvage in adult patients receiving HPN. MATERIALS AND METHODS: We retrospectively searched our prospectively maintained HPN database for the records of all adult patients receiving HPN from January 1, 1990, to December 31, 2013, at our tertiary referral center. Data abstracted from the medical records included demographics, diseases, treatments, and outcomes. The incidence of CRBSI and rates of catheter salvage were determined. RESULTS: Of 1040 patients identified, 620 (59.6%) were men. The median total duration on HPN was 124.5 days (interquartile range, 49.0-345.5 days). Mean (SD) age at HPN initiation was 53.3 (15.3) years. During the study period, 465 CRBSIs developed in 187 patients (18%). The rate of CRBSI was 0.64/1000 catheter days. Overall, 70% of catheters were salvaged (retained despite CRBSI) during the study period: 78% of infections with coagulase-negative staphylococci, 87% with methicillin-sensitive Staphylococcus aureus, and 27% with methicillin-resistant S aureus. The percentage of catheters salvaged was 63% from 1990 to 1994, 63% from 1995 to 1999, 61% from 2000 to 2004, 72% from 2005 to 2009, and 76% from 2010 to 2013. CONCLUSION: Catheter salvage is possible after a CRBSI episode. Since most episodes of CRBSI are caused by skin commensals, effective treatment without removal of the central venous catheter is possible in most cases.

Accuracy of Intravenous Electrocardiography Confirmation of Peripherally Inserted Central Catheter for Parenteral Nutrition.

BACKGROUND: Parenteral nutrition (PN) is a life-saving therapy for patients with intestinal failure. Safe delivery of hyperosmotic solution requires a central venous catheter (CVC) with tip in the lower superior vena cava (SVC) or at the SVC-right atrium (RA) junction. To reduce cost and delay in use of CVC, new techniques such as intravascular electrocardiogram (ECG) are being used for tip confirmation in place of chest x-ray (CXR). The present study assessed for accuracy of ECG confirmation in home PN (HPN). METHODS: Records for all patients consulted for HPN from December 17, 2014, to June 16, 2015, were reviewed for patient demographics, diagnosis leading to HPN initiation, and ECG and CXR confirmation. CXRs were subsequently reviewed by a radiologist to reassess location of the CVC tip and identify those that should be adjusted. RESULTS: Seventy-three patients were eligible, and after assessment for research authorization and postplacement CXR, 17 patients (30% male) with an age of 54 ± 14 years were reviewed. In all patients, postplacement intravascular ECG reading stated tip in the SVC. However, based on CXR, the location of the catheter tip was satisfactory (low SVC or SVC-RA junction) in 10 of 17 patients (59%). CONCLUSION: Due to the high osmolality of PN, CVC tip location is of paramount importance. After radiology review of CXR, we noted that 7 of 17 (41%) peripherally inserted central catheter lines were in an unsatisfactory position despite ECG confirmation. With current data available, intravenous ECG confirmation should not be used as the sole source of tip confirmation in patients receiving HPN.

RK-1355A and B, novel quinomycin derivatives isolated from a microbial metabolites fraction library based on NPPlot screening.

Two novel quinomycin derivatives, RK-1355A (1) and B (2), and one known quinomycin derivative, UK-63,598 (3), were isolated from a microbial metabolites fraction library of Streptomyces sp. RK88-1355 based on Natural Products Plot screening. The structural elucidation of 1 and 2 was established through two-dimensional NMR and mass spectrometric measurements. They belong to a class of quinomycin antibiotics family having 3-hydroxyquinaldic acid and a sulfoxide moiety. They are the first examples for natural products as a quinoline type quinomycin having a sulfoxide on the intramolecular cross-linkage. They showed potent antiproliferative activities against various cancer cell lines and they were also found to exhibit moderate antibacterial activity.