Antibacterial Meroterpenoids, Merochlorins G–J from the Marine Bacterium Streptomyces sp.

Four new chlorinated meroterpenoids, merochlorins G−J (1−4), and 10, a dihydronaphthalenedione precursor, along with known merochlorins A (5) and C−F (6−9), were obtained from cultivation of the bacterium strain Streptomyces sp. CNH-189, which was isolated from marine sediment. The planar structures of compounds 1−4 and 10 were elucidated by interpretation of MS, UV, and NMR spectroscopic data. The relative configurations of compounds 1−4 were determined via analysis of nuclear Overhauser effect (NOE) spectroscopic data, after which their absolute configurations were established by comparing the experimental electronic circular dichroism (ECD) spectra of compounds 1−4 to those of previously reported possible enantiomer models and DP4 calculations. Compound 3 displayed strong antibacterial activities against Bacillus subtilis, Kocuria rhizophila, and Staphylococcus aureus, with MIC values of 1, 2, and 2 μg/mL, respectively, whereas compound 1 exhibited weak antibacterial effects on these three strains, with a 16−32 μg/mL MIC value range.

High-affinity tamoxifen analogues retain extensive positional disorder when bound to calmodulin

Using a combination of NMR and fluorescence measurements, we have investigated the structure and dynamics of the complexes formed between calcium-loaded calmodulin (CaM) and the potent breast cancer inhibitor idoxifene, a derivative of tamoxifen. High-affinity binding (Kd∼300 nM) saturates with a 2:1 idoxifene:CaM complex. The complex is an ensemble where each idoxifene molecule is predominantly in the vicinity of one of the two hydrophobic patches of CaM but, in contrast with the lower-affinity antagonists TFP, J-8, and W-7, does not substantially occupy the hydrophobic pocket. At least four idoxifene orientations per domain of CaM are necessary to satisfy the intermolecular nuclear Overhauser effect (NOE) restraints, and this requires that the idoxifene molecules switch rapidly between positions. The CaM molecule is predominantly in the form where the N and C-terminal domains are in close proximity, allowing for the idoxifene molecules to contact both domains simultaneously. Hence, the 2:1 idoxifene:CaM complex illustrates how high-affinity binding occurs without the loss of extensive positional dynamics.

Concentration and Composition Dependent Aggregation of Pluronic- and Poly-(2-Oxazolin)-Efavirenz Formulations in Biorelevant Media

Interactions of intestinal fluids with polymer excipients, drugs and their formulations are not fully understood. Here, diffusion ordered spectroscopy (DOSY) and nuclear Overhauser effect spectroscopy (NOESY), complemented by cryo-TEM were employed to address this. Efavirenz as model drug, the triblock copolymers Pluronic F-127 (PF127) and poly(2-oxazolin) based pMeOx-b-pPrOzi-b-pMeOx (pOx/pOzi) and their respective formulations were studied in simulated fed-state intestinal fluid (FeSSIF). For the individual polymers, the bile interfering nature of PF127 was confirmed and pure pOx/pOzi was newly classified as non-interfering. A different and more complex behaviour was observed if EFV was involved. The formulations showed multi-facetted concentration and composition dependent aggregation. This demonstrates that separate evaluation of polymers or drugs in biorelevant media is not sufficient and their mixtures need to be carefully studied.<br>

Concentration and Composition Dependent Aggregation of Pluronic- and Poly-(2-Oxazolin)-Efavirenz Formulations in Biorelevant Media

Interactions of intestinal fluids with polymer excipients, drugs and their formulations are not fully understood. Here, diffusion ordered spectroscopy (DOSY) and nuclear Overhauser effect spectroscopy (NOESY), complemented by cryo-TEM were employed to address this. Efavirenz as model drug, the triblock copolymers Pluronic F-127 (PF127) and poly(2-oxazolin) based pMeOx-b-pPrOzi-b-pMeOx (pOx/pOzi) and their respective formulations were studied in simulated fed-state intestinal fluid (FeSSIF). For the individual polymers, the bile interfering nature of PF127 was confirmed and pure pOx/pOzi was newly classified as non-interfering. A different and more complex behaviour was observed if EFV was involved. The formulations showed multi-facetted concentration and composition dependent aggregation. This demonstrates that separate evaluation of polymers or drugs in biorelevant media is not sufficient and their mixtures need to be carefully studied.<br>

Five Tetramic Acid Derivatives Isolated from the Iranian Fungus Colpoma quercinum CCTU A372

Submerged mycelial cultures of the ascomycete Colpoma quercinum CCTU A372 were found to produce five previously undescribed tetramic acids, for which we propose the trivial names colposetins A–C (1–3) and colpomenoic acids A and B (4 and 5), along with the known compounds penicillide (6) and monodictyphenone (7). The planar structures of 1–5 were determined by high-resolution electrospray ionization mass spectrometry (HR-ESIMS) and extensive 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Their absolute configurations were determined by the combination of electronic circular dischroism (ECD) analysis, J-based configurational analysis, and a rotating-frame Overhauser effect spectroscopy (ROESY) experiment. Colposetin B displayed weak antimicrobial activity against Bacillus subtilis and Mucor hiemalis (MIC 67 µg/mL).

The Total Solubility of the Co-Solubilized PAHs with Similar Structures Indicated by NMR Chemical Shift

The synergism/inhibition level, solubilization sites and the total solubility (St) of co-solubilization systems of phenanthrene, anthracene and pyrene in Tween 80 and sodium dodecyl sulfate (SDS) are studied by 1H-NMR, 2D nuclear overhauser effect spectroscopy (NOESY) and rotating frame overhauser effect spectroscopy (ROESY). In Tween 80, inhibition for phenanthrene, anthracene and pyrene is observed in most binary and ternary systems. However, in SDS, synergism is predominant. After analysis, we find that different synergism or inhibition situation between Tween 80 and SDS is related to the different types of surfactants used and the resulting different co-solubilization mechanisms. In addition, we also find that three polycyclic aromatic hydrocarbons.

Cylindromicin from Arctic-Derived Fungus Tolypocladium sp. SCSIO 40433

The fungus strain SCSIO 40433 was isolated from an Arctic-derived glacier sediment sample and characterized as Tolypocladium cylindrosporum. A new compound, cylindromicin (1), and seven known secondary metabolites (2–8) were isolated from this strain. The chemical structures of these compounds were elucidated by comprehensive spectroscopic analyses. Cylindromicin (1) featured a 3,4-dihydro-2H-pyran skeleton. The absolute configuration of compound 1 was assigned via interpretation of key Nuclear Overhauser Effect Spectroscopy (NOESY) correlations and Electronic Circular Dichroism (ECD) calculation. Cylindromicin (1) exhibited significant tyrosinase inhibition activity. This study highlights Polar fungi as a potential resource for new bioactive natural products.