Synthesis and biological evaluation of novel thio-substituted chromanes as high-affinity partial agonists for the estrogen receptor.

Synthesis of (+/-)-cis-7-hydroxy-3-phenyl-4-(4-(2-piperidinoethanethio)phenyl)chromane (13) and (+/-)-cis-7-hydroxy-3-phenyl-4-(4-(2-pyrrolidinoethanethio)phenyl)chromane (15) is presented. These compounds are representatives of a novel class of compounds with high in vitro binding affinity for the estrogen receptor (IC(50)=7-10 nM), and very low in vitro uterotrophic activity (max stim.=5-17% rel to moxestrol; EC(50)=0.5-1.8 nM).     

Comparative study of DNA enzymes and ribozymes against the same full-length messenger RNA of the vanilloid receptor subtype I.

The efficiencies of 32 antisense oligodeoxynucleotides, 35 DNA enzymes and 6 ribozymes to bind and cleave the full-length messenger RNA of the vanilloid receptor subtype I were analyzed. Systematic screening of the mRNA revealed that good accessibility of a putative cleavage site for antisense oligodeoxynucleotides is a necessary but not a sufficient prerequisite for efficient DNA enzymes. Comparison of DNA enzymes and ribozymes against the same target sites revealed: 1) DNA enzymes were more active with longer recognition arms (9 nucleotides on either side), whereas ribozymes revealed higher activities with shorter recognition arms (7 nucleotides on either side). 2) It does not only depend on the target site but also on the enzyme sequence, whether a DNA enzyme or a ribozyme is more active. 3) The most efficient DNA enzyme found in this study had an approximately 15-fold higher reaction rate, k(react), and a 100-fold higher k(react)/K(m) under single turnover conditions compared with the fastest ribozyme. DNA enzymes as well as ribozymes showed significant activity under multiple turnover conditions, the DNA enzymes again being more active. We therefore conclude that DNA enzymes are an inexpensive, very stable and active alternative to ribozymes for the specific cleavage of long RNA molecules.     

<Emphasis Type=Italic>Filifactor alocis</Emphasis> - involvement in periodontal biofilms

Background  

Bacteria in periodontal pockets develop complex sessile communities that attach to the tooth surface. These highly dynamic microfloral environments challenge both clinicians and researchers alike. The exploration of structural organisation and bacterial interactions within these biofilms is critically important for a thorough understanding of periodontal disease. In recent years, Filifactor alocis, a fastidious, Gram-positive, obligately anaerobic rod was repeatedly identified in periodontal lesions using DNA-based methods. It has been suggested to be a marker for periodontal deterioration. The present study investigated the epidemiology of F. alocis in periodontal pockets and analysed the spatial arrangement and architectural role of the organism in in vivo grown subgingival biofilms.     

A fluorescent redox sensor with tuneable oxidation potential

A fluorescent redox sensor was prepared by attachment of hydroquinones to the fluorophore rhodamine B; fluorescence is reversibly modulated by hydroquinone-centered chemical redox reactions, and oxidation potential of the sensor is tuneable by variation of hydroquinone structure.     

HPTLC Autography Based Screening and Isolation of Mushroom Tyrosinase Inhibitors of European Plant Species

In the course of this project, 133 plants were evaluated on their ability to inhibit tyrosinase, a key enzyme in melanogenesis. The screening was performed by means of a HPTLC autographic assay, resulting in the selection of three plants, Asplenium trichomanes, Pinus uncinata, and Scutellaria altissima, with promising tyrosinase inhibiting activities. With the aid of the HPTLC assay, it was not only possible to select the most interesting plant extracts, but also to monitor the activity‐guided fractionation which, in a relatively short time period, led to the isolation of active principles. Benzoic acid, roseoside, and dihydrovomifoliol‐O‐β‐d ‐glucopyranoside could be identified as tyrosinase inhibitors present in P. uncinata. Globularin turned out to be the active principle of S. altissima, and 4‐ethenylphenyl 6‐O‐(6‐deoxy‐α‐l ‐mannopyranosyl)‐β‐d ‐glucopyranoside was detected as tyrosinase inhibitor of A. trichomanes. The pure compounds were tested also in a 96 well‐plate assay in order to determine their IC₅₀ values. The lowest IC₅₀ value (42 μm ) could be obtained for globularin, whereas the other compounds, e. g., benzoic acid exhibited a rather high IC₅₀ value (IC₅₀=552 μm ). This stood in clear contrast to the autographic assay, but is has to be taken into account that the outcome of the autography assay is not only depending on the IC50 value of a compound, but also on the content of the respective constituent in the extract.