Chemical quality evaluation and characteristics of interspecific hybrid (G. uralensis × G. glabra) C-18 strain as a new Licorice cultivar.

The development of new cultivars is essential for establishing a method of producing licorice in Japan. A suitable new cultivar for domestic licorice production, known as the interspecific hybrid strain C-18, was developed by crossbreeding Glycyrrhiza uralensis Fisch. (as the seed parent, possessing a high glycyrrhizin (GL) content, strain OMP-28) and Glycyrrhiza glabra L. (as the pollen parent, known for vigorous growth, strain OMP-10). Both G. uralensis and G. glabra are specified in the Pharmacopoeia of Japan (18th edition) as the source plants for Glycyrrhizae Radix. After 2 years of cultivation, strain C-18 exhibited robust growth, with a fresh weight of 148.8 g and a stem diameter of 0.89 mm. The GL content in the dry weight was measured at 3.61%. Seedlings cultivated from rhizomes in the field for 2 years showed a tap root fresh weight per plant of 120 ± 21 g, with an average GL content relative to the dry weight of 2.68% ± 0.38%. Although glabridin, a characteristic compound of G. glabra, was not detected, glycycoumarin, a characteristic compound of G. uralensis, was detected via HPLC analysis. Strain C-18 contained glycycoumarin as a characteristic compound of G. uralensis but lacked glabridin, a compound characteristic of G. glabra. Additionally, 2,3-dehydrokievitone (1) and parvisoflavone A (2) were identified as distinctive components of the interspecific hybrid (G. uralensis × G. glabra) C-18.

Seasonal variation in the total saponin content of platycodon roots cultivated in Japan.

Roots of Platycodon grandiflorus A. De Candolle (Campanulaceae), with the bark removed, have been used as food and frequently employed as herbal medicines for inflammatory diseases such as tonsillitis, dermatitis, and cough. Platycodins are the bioactive saponin components of these crude medicines. Recently, P. grandiflorus have been cultivated in Japan and are harvested from October to December according to conventional practices. Seasonal fluctuations in the total saponin content of these roots were determined using LC/MS methods to recommend harvesting times when the saponin content is high. Platycodins A and C are monoacetylated forms of platycodin D; however, the acetyl form is unstable and deacetylates easily. Here, the contents of platycodin D, platycodin D2, and platyconic acid A were measured as the total saponin content using alkaline hydrolysis for monoacetylated platycodins D, D2, and platyconic acid A. The results demonstrated that the saponin content in the roots decreased in summer, increased in autumn, but decreased again in late autumn.

Structure of metallo-beta-lactamase IND-7 from a Chryseobacterium indologenes clinical isolate at 1.65-A resolution.

The X-ray crystal structure of metallo-beta-lactamase from Chryseobacterium indologenes IND-7 was determined at a resolution of 1.65 A. The overall structure adopted a four-layered alphabeta/betaalpha sandwich structure with a dinuclear zinc(II) active site, in which the zinc(II) ions were denoted as Zn1 and Zn2. The overall structure of IND-7 is analogous to those of subclass B1 metallo-beta-lactamases, as determined by X-ray crystallography. A significant structural difference, however, was observed in the dinuclear zinc(II) active site: the coordination geometry around Zn1 changed from tetrahedral, found in other subclass B1 metallo-beta-lactamases, to distorted trigonal bipyramidal, whereas that of Zn2 changed from trigonal bipyramidal to tetrahedral. Arg121(101), which is located in the vicinity of the dinuclear zinc(II) active site, may affect the binding affinity of Zn2 due to an electronic repulsion between the zinc(II) ion(s) and a positively charged guanidyl group of Arg121(101). Moreover, the hydrogen-bonding interaction of Arg121 with Ser71(53), which is conserved in IND-1, IND-3 and IND-5-IND-7, appeared to have important consequences for the binding affinity of Zn2 in conjunction with the above electrostatic effect.

Structure of AmpC beta-lactamase (AmpCD) from an Escherichia coli clinical isolate with a tripeptide deletion (Gly286-Ser287-Asp288) in the H10 helix.

The X-ray crystal structure of AmpC beta-lactamase (AmpC(D)) with a tripeptide deletion (Gly286-Ser287-Asp288) produced by Escherichia coli HKY28, a ceftazidime-resistant strain, was determined at a resolution of 1.7 A. The structure of AmpC(D) suggests that the tripeptide deletion at positions 286-288 located in the H10 helix causes a structural change of the Asn289-Asn294 region from the alpha-helix present in the native AmpC beta-lactamase of E. coli to a loop structure, which results in a widening of the substrate-binding site.