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Biomedical subjects

R Franke

Publications and source records attributed to R Franke.

At least 55 records · Page 3Linked to original sources
PubMed1979

Discriminant--analytical investigation on the structural dependence of hyperglycemic and hypoglycemic activity in a series of substituted o-toluenesulfonylthioureas and o-toluenesulfonylureas.

The influence of a series of substituted o-toluenesulfonylthioureas and o-toluenesulfonylureas on the level of blood sugar was investigated in rats. According to the observed response the compounds were divided into three classes corresponding to hypoglycemic, hyperglycemic, and no activity. The distribution of the compounds over these classes can be described by discriminant functions using substituent constants, RM values, and indicator variables. Most important for the separation of classes are hydrophobic and/or steric properties as well as the presence or absence of the thiomide group. The results indicate that two different mechanisms of action with opposite effect overlap in the case of the series studied.

Animals↗
PubMed1979

On the interpretability of quantitative structure-activity relationships (QSAR).

QSAR are a powerful tool to obtain information on the molecular mechanism of drug action as well as on properties of receptors. They can be evaluated at different levels of sophistication using different parameters to describe physical chemical properties of the drugs and different mathematical methods. In this presentation only QSAR at the level of extrathermodynamic parameters will be considered. Interpretation of QSAR is always connected with two basic questions: 1) Which requirements must be met in order to get meaningful (interpretable) QSAR and what can be done to satisfy these requirements? 2) What information can be gained (and in which way) from QSAR? Some of the most important aspects of these questions to be discussed in this paper are: 1) Interrelationships between parameters and the separability of hydrophobic, electronic and steric effects. 2) Description of hydrophobic interactions. 3) Separation of hydrophobic effects connected with transport and hydrophobic bonding. 4) Estimation of the biological point of attack. 5) Selection and informational content of biological response data. Factor analysis will be shown to be a useful data preprocessing step allowing one to systematize data and to recognize and to eliminate collinearities. Another multivariate method, principal component analysis, may be used to separate pharmacokinetic and pharmacodynamic effects.

Biological Transport↗
PubMed1979

Hydrophobic binding of phenoxyacetic and phenylacetic acids to horseradish peroxidase and human serum albumin: structure-activity relationships.

Studies of protein binding in homologous series of drugs are of great interest for drug research. Apparent binding constants of phenoxyacetic and phenylacetic acids to horseradish peroxidase and to human serum albumin are evaluated by NMR studies and an optical method. These constants are good parameters to describe hydrophobic interactions, and the results are in a good agreement with our protein binding model described previously.

Chemical Phenomena↗
PubMed1978

Antiviral activity of dipyridamole derivatives.

Among 46 novel pyrimido [5.4-d] pyrimidine derivatives, 26 compounds were found to exhibit antiviral activity as revealed in a test programme against Mengo, Coxsackie B1, fowl plague, vaccinia and pseudorabies viruses, as concerns inhibition of plaque formation and of infectious virus yield. Attempts to disclose structure-activity relationships by discriminant analysis pointed to a possible importance of hydrophobic substitution for the antiviral effectiveness against Mengo virus of the derivatives investigated.

Antiviral Agents↗
PubMed1978

A simple method to obtain an approximate solution of the Free-Wilson model.

A method is proposed which yields an approximate solution of the Free-Wilson model very rapidly without using a computer. Although the resulting group contributions are numerically somewhat different from the exact Free-Wilson solution they correctly reflect the relative order of the substituents with respect to their effect on biological activity within each position as well as the relative importance of different positions. Thus, the approximate results can well be used to select the most promising candidates for further synthesis and testing.

Antimalarials↗
PubMed1977

[Nitrogen utilization and xanthan production by Xanthomonas campestris].

In media with mixed nitrogen sources (nitrate plus yeast extract) a three auxic growth is observed. The first growth phase is characterized by preferential utilization of the amino acids of the yeast autolysate and the utilization of only small amounts of nitrate. During the second growth phase nitrate is preferentially utilized. In the third phase there is only growth without dividing of cells and the accumulation of xanthan takes place. The change from growth by dividing to growth without dividing means a change from balanced to unbalanced growth. It is proposed that xanthan production is connected with unbalanced growth.

Amino Acids↗
PubMed1976

[Discriminant-analytic structure-effect relationship of qualitative biological data. Virostatic effect of isatin-beta-isothiosemicarbazones].

"Yes/No" results from the plaque-diffusion inhibition test concerning the virostatic activity of substituted isatin-beta-isothiosemicarbazones against mengo- and vaccinia-viruses can be described discriminant analytically by means of simple substituent constants. The discriminant analysis permits quantitative structure-activity analysis of qualitative and semi-quantitative test data, thus offering a chance for theoretical synthesis optimization already at the level of rough screening.

Indoles↗