A DFT STUDY ON THE HYDROLYSIS MECHANISM OF THE NAMI-A-TYPE ANTITUMOR COMPLEX (HL)[trans-RUCl4L(dmso-S)](L=4-amino-1,2,4-triazole)

The hydrolysis process of Ru (III) complex (HL)[trans- RuCl 4L(dmso-S)] (L=4-amino-1,2,4-triazole) (1), a potential antitumor complex similar to the well-known antitumor agent (ImH)[trans- RuCl 4(dmso-S)(Im)](NAMI-A), was investigated using density functional theory (DFT) with the conductor-like polarizable continuum model (CPCM). The structural characteristics and the detailed energy profiles for the hydrolysis processes of this complex were obtained. For the first hydrolysis step, complex 1 with 4-amino-1,2,4-triazole ligand shows much faster aquation than NAMI-A with imidazole ligand and complex 2 with 4H-1,2,4-triazole ligand, and such a calculated result is in good agreement with the experimental one. For the second hydrolysis step, the formation of cis-diaqua products is found to be thermodynamically preferred over the trans isomers. In addition, on the basis of the analysis of electronic characteristics of species in the hydrolysis process, the trend in abilities (A) of hydrolysis products attacked nucleophilicly by pertinent biomolecules is revealed. These theoretical results will help in understanding the action mechanism of this potential Ru (III) drug with pertinent biomolecular targets.

3D-QSAR STUDIES OF SUBSTITUTED 4-ARYL/HETEROARYL-4H-CHROMENES AS APOPTOSIS INDUCERS USING CoMFA AND CoMSIA

Three-dimensional (3D) quantitative structure–activity relationships (QSARs) of 36 apoptosis inducers, substituted 4-aryl/heteroaryl-4H-chromenes with anticancer activity against human breast cancer cell lines T47D, have been studied by using methods of comparative molecular field analysis (CoMFA) and comparative molecular similarity analysis (CoMSIA). The established 3D-QSAR models in training set show not only significant statistical quality, but also predictive ability, with high correlation coefficient (R2) values and cross-validation coefficient (q2) values: CoMFA (R2, q2: 0.944, 0.747), CoMSIA (R2, q2: 0.944, 0.704). Moreover, the predictive abilities of the CoMFA and CoMSIA models were further confirmed by a test set, giving the predictive correlation coefficients ([Formula: see text] values) of 0.845 and 0.851, respectively. Based on the CoMFA and CoMSIA contour map analyses, some key factors responsible for anticancer activity of this series of compounds have been found as follows: the steric interaction plays a decisive role in determining the anticancer activities of these compounds; bulky groups as substituent R 1 are not tolerated; in addition to a steric moderation, higher degree of electropositivity and hydrophobicity on the terminal alkyl of substituent R 2 might be favorable to the activity; the substituent R 3 should be hydrophobic; bulky and strong electron withdrawing groups for the substituent R 4 are not advantageous to the activity; simultaneously introducing large electronegative atoms as hydrogen-acceptors to the first atoms of the substituents R 5 and R 6 may increase the activity, but substituents R 5 and R 6 with a linking group – OCH 2 O – may decrease the activity. Such results can offer some useful theoretical references for understanding the action mechanism, designing more potent derivatives, and predicting their activities prior to synthesis.

QSAR AND ACTION MECHANISM OF TROXACITABINE PRODRUGS WITH ANTITUMOR ACTIVITY

The quantitative structure–activity relationship (QSAR) of troxacitabine prodrugs with antitumor activity has been studied by using the density functional theory (DFT), molecular mechanics (MM2), and statistical methods. The established QSAR model shows not only significant statistical quality, but also predictive ability, with the square of adjusted correlation coefficient [Formula: see text] and the square of the cross-validation coefficient (q2 = 0.807). The antitumor activity is expressed as p IC50, which is defined as the negative value of the logarithm of necessary molar concentration of a compound to cause 50% growth inhibition against the human non-small-cell lung cancer cell line SW1573. It appears to be mainly governed by two factors (or original variables), i.e. the calculated hydrophobic coefficient (C log P) of whole molecule and the net charges of the first atom of substituent R (Q FR ), although three descriptors, i.e. C log P, (C log P)2, and Q FR , were selected in our multiple linear regression model. The factor C log P shows parabolic relation to p IC50 and its suitable range is around 5.6, and the other factor Q FR shows a significant negative correlation with p IC50. In this paper, a detailed discussion on these two factors was carried out, and their close correlation with the action mechanism of these prodrugs was reasonably revealed. Such results can offer some useful theoretical references for understanding the action mechanism and directing the molecular design of this kind of compound with antitumor activity.

2D/3D-QSAR STUDY ON ANALOGUES OF 2-METHOXYESTRADIOL WITH ANTICANCER ACTIVITY

Two-dimensional (2D) and three-dimensional (3D) quantitative structure–activity relationships (QSARs) of 23 analogs of 2-Methoxyestradiol with anticancer activity (expressed as p GI50) against MCF-7 human breast cancer cells have been studied by using a combined method of the DFT, MM2 and statistics for 2D, as well as the comparative molecular field analysis (CoMFA) for 3D. The established 2D-QSAR model in training set shows not only significant statistical quality, but also predictive ability, with the square of adjusted correlation coefficient [Formula: see text] and the square of the cross-validation coefficient (q2= 0.779). The same model was further applied to predict p GI50values of the four compounds in the test set, and the resulting [Formula: see text] being as high as 0.827, further confirms that this 2D-QSAR model has high predictive ability for this kind of compound. The 3D-QSAR model also shows good correlative and predictive capabilities in terms of R2(0.927) and q2(0.786) obtained from CoMFA model. The results that 2D- and 3D-QSAR analyses accord with each other, suggest that the electrostatic interaction plays a decisive role in determining the anticancer activity of the studied compounds, and that increasing the negative charge of substituent R2and the positive charge of substituents linking to C17as well as decreasing the size of substituent R1are advantageous to improving the cytotoxicity. Such results can offer some useful theoretical references for directing the molecular design and understanding the action mechanism of this kind of compound with anticancer activity.