Medicinal flowers. XVII. New dammarane-type triterpene glycosides from flower buds of American ginseng, Panax quinquefolium L

Five new dammarane-type triterpene glycosides, floralquinquenosides A, B, C, D, and E, were isolated from the flower buds of American ginseng, Panax quinquefolium L., together with 18 known dammarane-type triterpene glycosides and 3 flavonoid glycosides. The structures of new floralquinquenosides were elucidated on the basis of chemical and physicochemical evidence.     

Improvement in the quality of hematopoietic prostaglandin D synthase crystals in a microgravity environment

Human hematopoietic prostaglandin synthase, one of the better therapeutic target enzymes for allergy and inflammation, was crystallized with 22 inhibitors and in three inhibitor-free conditions in microgravity. Most of the space-grown crystals showed better X-ray diffraction patterns than the terrestrially grown ones, indicating the advantage of a microgravity environment on protein crystallization, especially in the case of this protein.     

Studies on the biosynthesis of the notoamides: synthesis of an isotopomer of 6-hydroxydeoxybrevianamide E and biosynthetic incorporation into notoamide J

6-Hydroxydeoxybrevianamide E is proposed as a biosynthetic precursor to several advanced metabolites isolated from both marine-derived Aspergillus sp. and a terrestrial-derived Aspergillus versicolor. To verify the role of this reverse-prenylated indole alkaloid as an intermediate along the biosynthetic pathway, [(13)C](2)-[(15)N]-6-hydroxydeoxybrevianamide E was synthesized and fed to Aspergillus versicolor. Analysis of the metabolites showed incorporation of the intermediate only into the natural product notoamide J.     

Unique self-anhydride formation in the degradation of cytidine-5'-monophosphosialic acid (CMP-Neu5Ac) and cytidine-5'-diphosphosialic acid (CDP-Neu5Ac) and its application in CMP-sialic acid analogue synthesis

Sialyloligosaccharides are synthesised by various glycosyltransferases and sugar nucleotides. All of these nucleotides are diphosphate compounds except for cytidine-5'-monophosphosialic acid (CMP-Neu5Ac). To obtain an insight into why cytidine-5'-diphosphosialic acid (CDP-Neu5Ac) has not been used for the sialyltransferase reaction and why it is not found in biological organisms, the compound was synthesised. This synthesis provided the interesting finding that the carboxylic acid moiety of the sialic acid attacks the attached phosphate group. This interaction yields an activated anhydride between carboxylic acid and the phosphate group and leads to hydrolysis of the pyrophosphate linkage. The mechanism was demonstrated by stable isotope-labelling experiments. This finding suggested that CMP-Neu5Ac might also form the corresponding anhydride structure between carboxylic acid and phosphate, and this seems to be the reason why CMP-Neu5Ac is acid labile in relation to other sugar nucleotides. To confirm the role of the carboxylic acid, CMP-Neu5Ac derivatives in which the carboxylic acid moiety in the sialic acid was substituted with amide or ester groups were synthesised. These analogues clearly exhibited resistance to acid hydrolysis. This result indicated that the carboxylic acid of Neu5Ac is associated with its stability in solution. This finding also enabled the development of a novel chemical synthetic method for CMP-Neu5Ac and CMP-sialic acid derivatives.     

In situ synthesis of polysaccharide nanoparticles via polyion complex of carboxymethyl cellulose and chitosan

Biocompatible polymer-magnetite hybrid nanoparticles were prepared by means of in situ synthesis of magnetite within polysaccharide hydrogel nanoparticles. Hydrogel nanoparticles were first fabricated by blending high-molecular-weight carboxymethyl cellulose as an anionic polymer, and low-molecular-weight chitosan as a cationic polymer to form polyion complexes (CC particles). These polyion complexes were then chemically crosslinked using genipin, a bio-based cross-linker, to form stable nanoparticles having a semi-IPN structure (CCG particles). Magnetite was lastly synthesized within CCG particles by the coprecipitation method to obtain polymer-magnetite hybrid nanoparticles (CCGM particles). The formations of CC, CCG and CCGM particles were mainly observed by transmittance, absorbance of genipin and TEM, respectively, and their hydrodynamic diameters and zeta-potentials were analyzed. It was confirmed that the hydrodynamic diameters and the zeta-potentials of these particles were significantly influenced by pH of the suspension, which was attributed to the charges of polymers. The diameters of CCGM particles were smaller than 200 nm at any pH conditions, suggesting the possibility to apply them as drug delivery carriers. CCGM particles exhibited the responsiveness to a magnetic field in addition to their high dispersion stability, indicating their potential to be utilized as a biomaterial for hyperthermia.     

Intramolecular charge resonance in dimer radical anions of di-, tri-, tetra-, and pentaphenylalkanes

Intramolecular dimer radical anions of di-, tri-, tetra-, and pentaphenylalkanes were investigated on the basis of absorption spectral measurements during γ-radiolysis in 2-methyltetrahydrofuran (MTHF) glassy matrix at 77 K and theoretical calculations. The absorption spectrum of 1,1,2,2-tetraphenylethane (1,1,2,2-Ph(4)E) radical anion showed two bands in the near-infrared (NIR) region (900-2600 nm). One band observed at shorter wavelength than 2000 nm is assigned to the intramolecular charge resonance (CR) band between two phenyl groups of the 1,1-diphenylmethyl chromophore (1,1-dimer radical anion). The intramolecular CR band of the 1,1-dimer radical anion was observed for various alkanes having 1,1-diphenylmethyl chromophore such as 1,1,1-triphenylmethane (1,1,1-Ph(3)M), 1,1,1,1-tetraphenylmethane (1,1,1,1-Ph(4)M), and so on. The other intramolecular CR band observed at longer wavelength than 2200 nm is assigned to intramolecular dimer radical anion between two phenyl groups of the 1,2-diphenylethyl chromophore (1,2-dimer radical anion). The intramolecular CR band of the 1,2-dimer radical anion was observed for various alkanes having a 1,2-diphenylethyl chromophore, such as 1,1,2-triphenylethane (1,1,2-Ph(3)E), 1,1,2,2-Ph(4)E, and 1,1,1,2,2-pentaphenylethane (1,1,1,2,2-Ph(5)E) and so on. No dimer radical anion was observed for 1,n-diphenylalkanes (n > 2) without 1,1-diphenylmethyl chromophore. The relationship between the structure and negative charge delocalization over two phenyl groups connected by an sp(3) carbon is discussed.     

Quantitative O imaging towards oxygen consumption study in tumor bearing mice at 7 T

¹⁷O magnetic resonance imaging (MRI) using a conventional pulse sequence was explored as a method of quantitative imaging towards regional oxygen consumption rate measurement for tumor evaluation in mice. At 7 T, fast imaging with steady state (FISP) was the best among gradient echo, fast spin echo and FISP for the purpose. The distribution of natural abundance H₂¹⁷O in mice was visualized under spatial resolution of 2.5 × 2.5 mm² by FISP in 10 min. The signal intensity by FISP showed a linear relationship with ¹⁷O quantity both in phantom and mice. Following the injection of 5% ¹⁷O enriched saline, ¹⁷O re-distribution was monitored in temporal resolution down to 5 sec with an image quality sufficient to distinguish each organ. The image of labeled water produced from inhaled ¹⁷O₂ gas was also obtained. The present method provides quantitative ¹⁷O images under sufficient temporal and spatial resolution for the evaluation of oxygen consumption rate in each organ. Experiments using various model compounds of R-OH type clarified that the signal contribution of body constituents other than water in the present in vivo¹⁷O FISP image was negligible.     

Inactivation Activities of Ozonated Water,Slightly Acidic Electrolyzed Water and Ethanol against SARS-CoV-2

This study aimed to compare the SARS-CoV-2-inactivation activity and virucidal mechanisms of ozonated water (OW) with those of slightly acidic electrolyzed water (SAEW) and 70% ethanol (EtOH). SARS-CoV-2-inactivation activity was evaluated in a virus solution containing 1%, 20% or 40% fetal bovine serum (FBS) with OW, SAEW or EtOH at a virus-to-test solution ratio of 1:9, 1:19 or 1:99 for a reaction time of 20 s. EtOH showed the strongest virucidal activity, followed by SAEW and OW. Even though EtOH potently inactivated the virus despite the 40% FBS concentration, virus inactivation by OW and SAEW decreased in proportion to the increase in FBS concentration. Nevertheless, OW and SAEW showed potent virucidal activity with 40% FBS at a virus-to-test solution ratio of 1:99. Real-time PCR targeting the viral genome revealed that cycle threshold values in the OW and SAEW groups were significantly higher than those in the control group, suggesting that OW and SAEW disrupted the viral genome. Western blotting analysis targeting the recombinant viral spike protein S1 subunit showed a change in the specific band into a ladder upon treatment with OW and SAEW. OW and SAEW may cause conformational changes in the S1 subunit of the SARS-CoV-2 spike protein.