Biomedical subjects

M Pickert

Publications and source records attributed to M Pickert.

5 recordsLinked to original sources

PubMed1999

Substituted xanthones as antimycobacterial agents. Part 3: QSAR investigations.

Quantitative Structure Activity-Relationships between the antituberculous activity of a series of 61 substituted xanthones and their 13C NMR chemical shifts, lipophilicity, and molar refractivities of the substituents were investigated. In addition to these structural parameters, the test concentrations of the compounds were considered because of the varying solubility. While the multiple linear regression-based Adaptive Least Squares analysis revealed only weak correlations between the antituberculous activity classes of the compounds and their physicochemical parameters, significantly better results were obtained by the Artificial Neural Network technique, which describes nonlinear relationships between the activity as dependent and the physicochemical parameters as independent variables.

Antitubercular Agents↗

PubMed1998

Substituted xanthones as antimycobacterial agents, Part 2: Antimycobacterial activity.

A series of substituted xanthones was tested for their activity against four mycobacterial strains (Mycobacterium tuberculosis, M. avium, M. lufu, M. smegmatis) by determination of the minimum inhibitory concentrations (MIC values). For the most active compounds, supplementary characterisation was performed by bacterial growth kinetics, which allows a more precise interpretation of their antimycobacterial effects. From the test set, 1-methyl-2,4,7-trinitroxanthone (8a) showed the highest antimycobacterial activity with a MIC value of 3 micrograms/mL against M. tuberculosis, which is comparable to the effect of well known drugs used in the treatment of tuberculosis. For all other compounds, the MIC values could not be determined, due to the comparatively low activity and to the poor solubility of the compounds, respectively. The semiquantitative evaluation of activity against the different strains of mycobacteria resulted in a classification into three activity classes, which will be used as dependent parameter in QSAR investigations, to be published in Part 3 of this series.

Anti-Bacterial Agents↗

PubMed1997

Quantitative structure-activity relationship (QSAR) study of polyhydroxyxanthones.

In the present study 13C-chemical shift additivity rules are developed for polyhydroxyxanthones with antituberculotic activity against Mycobacterium tuberculosis. QSAR investigations are performed by correlating 13C-chemical shifts and calculated dipole moments of several 1,3-substituted polyhydroxyxanthones with their antituberculotic activity and by using the CoMFA approach as a three-dimensional QSAR method.

Antitubercular Agents↗

PubMed1994

Cosmic ionizing radiation effects in plant seeds after short and long duration exposure flights.

Recently, comparison of biophysical data obtained from orbital flights of short and long duration led to results which will be significant for long and/or repeated stay of man in space. Under orbital conditions biological stress is induced in dry seeds of Arabidopsis thaliana by cosmic radiation especially its high energetic, densely ionizing component, the heavy ions (HZE). For comparison of radiation impact during different space flights a biological attempt at estimating the impact of single particles with high mass and energy (HZE-particles) on seeds was developed. Subdivision into LET-groups showed a remarkable contribution of an intermediate group (LET = 35 to 100 keV/micrometer) due to medium heavy ions (Z = 6 to 10). Efficiency factors for radiation damage experimentally determined and assigned to different LET-classes were compared to radiation quality factors discussed in literature.

Arabidopsis↗

PubMed1992

Heavy ion induced mutations in genetic effective cells of a higher plant.

Arabidopsis thaliana offers different possibilities for investigating heavy ion induced early and late damage. Mutations in genetic effective cells can yield early damage, in the form of reduced vitality of the descending cell-lines and/or late damage, such as mutation induction visible in the following generations. Investigation is possible on different levels of ploidy (4n, 2n, n). Different genetic effective cells with equal genomes are available. Additionally, several different biological endpoints for each level of genome ploidy can be observed. Recent results of work in this field are presented.

Arabidopsis↗