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Biomedical subjects

Corwin Hansch

Publications and source records attributed to Corwin Hansch.

At least 19 recordsLinked to original sources

Understanding human rhinovirus infections in terms of QSAR.

The human rhinoviruses (HRVs) are the single most important cause of common colds. The widespread nature of this affliction, the economic consequences, and the well-known impracticality of vaccine development due to the large number of HRV serotypes (>100) have justified the search for chemotherapeutic agents. The interest in the application of quantitative structure-activity relationships has steadily increased in recent decades and we hope it may be useful in the search for anti-HRV agents. In the present paper, we have discussed the inhibition of various six compound series against HRV-1A, -1B, -2, -9, -14, -21, -22, -25, -64, and -89 by the formulation of a total number of 14 QSAR. Hydrophobicity is found to be one of the most important determinants of activity. Parabolic correlation with the hydrophobic parameter (Eq. ) is an encouraging example, where the optimal hydrophobicity is well defined. We believe that this may be the predictive model to narrow the synthetic challenges in order to yield very specific HRV-2 inhibitors. On the basis of this model, we have predicted eleven compounds (I-1 to I-11) that may be the next synthetic target. The proposed molecules (I-1 to I-11) also fulfill the conditions of Lipinski's "rule of five".

Antiviral Agents↗

Utility of the mouse dermal promotion assay in comparing the tumorigenic potential of cigarette mainstream smoke.

The International Agency for Research on Cancer (IARC) has classified a number of the chemical constituents reported in cigarette mainstream smoke (MS) as carcinogens. In the international literature, 81 IARC classified carcinogens have been reported historically in MS. Cigarette smoke is a complex aerosol of minute liquid droplets (termed the particulate phase) suspended within a mixture of gases (CO(2), CO, NO(x), etc.) and semi-volatile compounds. The gases and semi-volatiles are termed the vapor phase. Due to early difficulties in inducing carcinomas in laboratory animals following inhalation exposure to MS, the mouse dermal promotion assay became the standard method of comparing the tumorigenic potential of cigarette smoke condensates (the particulate phase of MS nearly devoid of MS gases and having a significant reduction of the semi-volatile components of the vapor phase). Of the 81 IARC carcinogens reported in MS, 48 are found exclusively in the particulate phase, 29 in the vapor phase only, and four IARC carcinogens in both phases. A general comparison of the quantity and potency of the individual carcinogenic constituents of the MS vapor and particulate phases illustrates that the potential carcinogenic contribution from the vapor phase might be significant. Therefore, the mouse dermal promotion assay may not be a sensitive comparator of the tumorigenic potential of different MSs displaying a diversity of vapor phase components. However, when used in a weight-of-the-evidence approach that includes smoke chemistry, in vitro studies using whole smoke and human exposure studies evaluating both vapor and particulate phase smoke constituents, the mouse dermal promotion assay remains an important risk assessment tool as the only test that reproducibly measures the tumorigenic potential of cigarette smoke condensate.

Animals↗

Chemical Toxicity on HeLa Cells.

HeLa cells were named for Henrietta Lacks, who died in 1952 from an infection of a special type of cancer. Margaret Gey, her physician, started working with these cancer cells that are still used for medical research. In the present review, an attempt has been made to collect the data for the effects of different chemicals on HeLa cells and to discuss them by the formulation of a total number of 22 QSAR.

HeLa Cells↗

A QSAR study on influenza neuraminidase inhibitors.

Influenza is a major respiratory infection associated with significant morbidity in the general population and mortality in elderly and high-risk patients. It is an RNA virus that contains two major surface glycoproteins, neuraminidase and hemagglutinin. These proteins are essential for infection. Neuraminidase has been found to be a potential target to control influenza virus. In this paper, we have developed 17 quantitative structure-activity relationships (QSAR) for different sets of compounds to understand chemical-biological interactions governing their activities toward influenza neuraminidase.

Amides↗

A QSAR review on melanoma toxicity.

Melanoma is one of the most aggressive forms of skin cancer and is currently attracting our attention particularly in the area of quantitative structure-activity relationships (QSAR). In the present review, an attempt has been made to collect the data for different sets of compounds and to discuss their toxicities toward melanoma cells by the formulation of a total number of 36 QSAR.

Animals↗

An approach toward the problem of outliers in QSAR.

Compounds that have unexpected biological activity and are unable to fit in a QSAR model are known as outliers. These are valuable in defining the limitations under which compounds act by a common molecular mechanism modeled by one or more descriptors, and also in defining the experimental limitations of the biological test data. Thus, the outliers should be submitted to particular attention to see if the reason for their peculiarity can be determined. Separating these outliers from the main data set and formulating another QSAR can resolve the problem. Our result shows that these outliers may be acting by a different mechanism or interacting with the receptor in different modes.

Animals↗

The role of hydrophobic properties of chemicals in promoting allosteric reactions.

An allosteric reaction has been found in a variety of instances where an inverted parabolic relationship between biological activity and hydrophobicity is apparent, that is the activity first decreases as hydrophobicity increases and after a certain point, activity begins to increase. This could be attributed to the ligands causing a change in the receptor structure. In this report, the role of hydrophobic properties of chemicals in promoting allosteric reactions have been discussed in term of hydrophobicity (logP) by the formulation of a total number of 50 QSAR equations. The QSAR model of this type may be represented by Eq. I.

Allosteric Regulation↗

The role of QSAR in dopamine interactions.

Dopamine receptor blockers have been used for the treatment of schizophrenia for many years. We have developed 22 quantitative structure activity relationships (QSAR) for different sets of compounds to understand chemical-biological interactions governing their activities toward dopamine receptors.

Dopamine Agents↗

A comparison between two polarizability parameters in chemical--biological interactions.

The polarizability of a molecule, an important physical property, is currently attracting our attention particularly in the area of QSAR (quantitative structure-activity relationships) for chemical-biological interactions. Our primary focus in the present study has been upon the computational aspects by using NVE (sum of the valence electrons) as a means for estimating polarizability, we have been surprised at its utility. In this report we demonstrate how NVE can be related to the calculated polarizability from a variety of efforts to better understand the subject. A comparison between the use of two polarizability parameters, that is, NVE and CMR (calculated molar refractivity) in the formulation of QSAR for chemical-biological interactions has been also discussed.

Computer Simulation↗

Chemical-biological interactions in human.

Chemical-biological interactions in human are currently attracting our attention particularly in the area of QSAR (quantitative structure-activity relationships). In the present review, an attempt has been made to collect the data for the effect of chemicals in human and discussed by the formulation of a total number of 37 QSAR.

Biology↗

On the role of polarizability in QSAR.

The polarizability of a molecule, an important physical property, is currently attracting our attention particularly in the area of QSAR for chemical-biological interactions. In this report, the polarizability effects on ligand-substrate interactions has been discussed in terms of NVE (number of valence electrons) using additive values for valence electrons and the formulation of a total number of 51 QSAR. The QSAR model can be illustrated by Eq. I. log 1/C = a(NVE) +/- constant

Ligands↗

Elucidation of structure-activity relationships for 2- or 6-substituted-5,8-dimethoxy-1,4-naphthoquinones.

1,4-Naphthoquinones have already been recognized to possess a wide range of biological activities. We have developed quantitative structure activity relationships (QSAR) for different series of 2- or 6-substituted-5,8-dimethoxy-1,4-naphthoquinones to understand the chemical-biological interaction governing antiproliferative/cytotoxic activities against L1210 cells. QSAR results have shown that these activities of 2- or 6-substituted-5,8-dimethoxy-1,4-naphthoquinones depend largely on their hydrophobicity.

Animals↗

An Approach towards the quantitative structure-activity relationships of caffeic acid and its derivatives.

Caffeic acid and its derivatives are already known to possess a wide range of biological activities. We have developed quantitative structure-activity relationships (QSARs) for different series of caffeic acid derivatives (including caffeic acid) in order to understand the chemical-biological interactions governing antitumor activity against six different tumor cell lines, nitric oxide production, anti-HIV and enzymatic activities, and binding affinity to the lck domain. QSAR results have shown that the different activities of caffeic acid and its derivatives are largely dependent on their hydrophobicity or molar refractivity, with a bilinear correlation being the most important.

Algorithms↗

QSAR and ADME.

The prediction from structure of ADME (absorption, distribution, metabolism, elimination) of drug candidates is an important goal to achieve since it can considerably reduce the cost of drug development. Using our database of 10,700 QSAR, we are now reaching the point where we can make many useful comparisons that illustrate how ADME is a practical way to describe the way organic compounds react with living systems. We also show that Caco-2 cells are useful to model absorption, but the most generally useful parameter is the octanol/water partition coefficient. It should be noted, however, that in our opinion, an in silico prediction of ADME is still a long way in the future.

Animals↗

Percutaneous penetration enhancers in cigarette mainstream smoke.

Percutaneous penetration enhancers (PPEs) are chemicals used to enhance the transdermal delivery of drugs. Fifty-eight of the approximately 150 PPEs used for the transdermal delivery of drugs have been reported in cigarette mainstream smoke (MS). MS is a complex aerosol of minute liquid droplets (termed the particulate phase) suspended within a mixture of gases (CO(2), CO, NO(x), etc.) and semi-volatile compounds. The gases and many of the semi-volatiles are termed the vapor phase. Twenty-nine of the 58 PPEs have been identified in MS vapor phase, 15 in the particulate phase and 14 in both the vapor and particulate phases. There is a tendency for MS PPEs to be hydrophobic, with 40 of the 58 compounds (69%) being either hydrophobic or strongly hydrophobic, and only 24% being hydrophilic. Many of the 4800 known constituents of MS are hydrophilic and would not be expected to readily cross cell membranes or penetrate tissue when delivered as single compounds. The in vivo effect on biological activity of the juxtaposition within the cigarette smoke aerosol of the large number of hydrophilic constituents with the 58 PPEs is currently unknown. As an initial step in understanding this potential complex interaction, the 58 PPEs in MS have been identified and a number of molecular parameters related to the ability to penetrate tissue have been calculated, including MS concentration, measured and calculated base ten logarithm of the octanol-water partition coefficient (Mlog P and Clog P), molecular volume (MgVol) and calculated molar refractivity (CMR).

Administration, Cutaneous↗

QSAR of apoptosis induction in various cancer cells.

In continuing our QSAR study of apoptosis, we consider in this report the action of phenolic compounds on Ramos cells (non-Hodgkins B-cell lymphoma): the effect of O-8-thapsigargin analogues on human prostate cancer cells, Tsu-Pr-1 and the induction of apoptosis of a complex set of congeners on human fibrosarcoma cells HT 1080. The human prostate cancer cells activity is very similar to that of the Ramos cells. While the QSAR for the fibrosarcoma cells resembles that of our earlier study with L1210 leukemia cells. The two different types of QSAR suggest at least two quite different types of receptors for the induction of apoptosis.

Antineoplastic Agents↗