Medicinal Chemistry - Volume 6, Issue 5, 2010

Dopamine and its receptors play a critical role in diseases such as Parkinson's disease and schizophrenia. A problem with developing specific drugs for such diseases is that there are five subtypes of dopamine receptors that can be categorized as either D1 like or D2 like. Since the binding sites are quite similar, it is difficult to design the subtype specific agonists and antagonists required for therapy with minimal side effects. Thus, the aim of this study was to identify the molecular characteristics important to the selective binding of dopamine D1 like and D2 like receptors using quantitative structure activity relationships (QSARs). Datasets of 29 and 69 molecules capable of binding to cloned human D1 and D2 receptors were used to build QSAR models. The dissociation constants (Ki) for these molecules were taken from the literature. The optimized 3D structure of each molecule was encoded with 62 theoretical molecular descriptors. The QSAR, using hybrid neural network modeling, was built using categorical and continuous molecular descriptors as inputs, with dissociation constants (Ki) as outputs. Categorically assigned molecular descriptors improved performance in both models. Secondary amines and other nitrogen-containing moieties were shown to be important for the D1 like receptor selectivity, whereas molecular size, volume and tertiary and quaternary carbons were found to be of significant importance for the D2 like receptor selectivity.

The aim of this study was to investigate the effects of different ester groups in position 5' of stavudine on the transdermal penetration with and without the use of Pheroid™ as the delivery system. Six esters were prepared by reaction of stavudine with six different acid chlorides at room temperature. Female human abdominal skin was used for in vitro penetration in Franz diffusion cells. The experimental aqueous solubility of stavudine (104.75 mg/mL) was much higher than that of the synthesized derivatives (ranging from 0.08 to 5.17 mg/mL), while the log D (octanol-buffer partition coefficient) of stavudine (-0.85) was lower than that of its derivatives (ranging from -0.41 to 3.06). The experimental transdermal flux of stavudine (6.52 μmol/cm2.h) in PBS (phosphate buffer solution) was much higher than that of any of its derivatives (0.06 - 0.23 μmol/cm2.h), while the propionyl (6.64 μmol/cm2.h) and the butyryl esters (6.87 μmol/cm2.h) had the highest transdermal flux using the Pheroid™ (0.75 - 6.87 μmol/cm2.h) system.

The article describes the development of a robust pharmacophore model and the investigation of structure activity relationship analysis of 48 aminophenyl benzamide derivatives reported for Histone Deacetylase (HDAC) inhibition using PHASE module of Schrodinger software. A five point pharmacophore model consisting of two aromatic rings (R), two hydrogen bond donors (D) and one hydrogen bond acceptor (A) with discrete geometries as pharmacophoric features was developed and the generated pharmacophore model was used to derive a predictive atom-based 3D QSAR model for the studied dataset. The obtained 3D QSAR model has an excellent correlation coefficient value (r2=0.99) along with good statistical significance as shown by high Fisher ratio (F=631.80). The model also exhibits good predictive power confirmed by the high value of cross validated correlation coefficient (q2 = 0.85). The QSAR model suggests that hydrophobic character is crucial for the HDAC inhibitory activity exhibited by these compounds and inclusion of hydrophobic substituents will enhance the HDAC inhibition. In addition to the hydrophobic character, hydrogen bond donating groups positively contributes to the HDAC inhibition whereas electron withdrawing groups has a negative influence in HDAC inhibitory potency. The findings of the QSAR study provide a set of guidelines for designing compounds with better HDAC inhibitory potency.

Thioredoxin reductase plays a critical role in the regulation of cancer cell apoptosis, making it an attractive target for the design of new anticancer drugs. Several classes of compounds have been considered as potential antitumor or chemopreventive agents; most of them apparently interact with thioredoxin reductase's C-terminal redox center.

The mononuclear complex, [Co(TAMEN)](ClO4)2(DMSO), containing the Mannich base N,N'-tetra-(4- antipyrylmethyl)-1,2-diaminoethane (TAMEN) as ligand, was synthesized and characterised by conductometric, electronic and infrared spectroscopic properties. The single-crystal X-ray structure show the presence of two well defined units, [Co(TAMEN)]2+ and (ClO4)-. The complex cation contains cobalt(II) in the pseudo octahedral environment created by the N2O4 donor set of TAMEN. The cobalt(II) complex have been screened for its cytotoxic activity against three cultured human cell lines established from hepatoma (Hep G2), breast (MCF-7) and lung (A549) cancers as well as on nontumor bovine kidney (MDBK) cells. The cytotoxic activity of the ligand TAMEN was assessed on one tumor (Hep G2) and one non-tumor (MDBK) cell lines. The cobalt(II) compound was found to decrease in a time- and concentration- dependent manner the viability of tumor (A549, MCF-7, Hep G2) cell lines, while the ligand TAMEN expressed proliferative activity on hepatoma (HepG2) and bovine kidney (MDBK) cells, especially after prolonged incubation.

A range of isatin-thiazolidinone hybrid analogues were synthesized and their cytotoxicity was evaluated against several cancer cell lines in vitro. The acute toxicity studies in mice models revealed that these analogues possess low systemic toxicity and are safe up to 1600mg/Kg. Among the compounds synthesized, 5-(2-nitrobenzylidene)-2-(isatin-3- azino)-thiazolidin-4-one (CI) has been shown to be the most active, highly promising compound which induced S phase arrest in cell cycle in a time dependent manner. Our initial analysis indicate that incorporation of electron withdrawing group at ortho position of the ring favors over the meta and para positions for eliciting its cytostatic effect. Overall, the in vitro biological evaluation suggests that the growth inhibitory effect of CI is promising and can be studied further.

The present study describes the chemical synthesis and anticonvulsant activity evaluation of a series of 7- alkoxy-triazolo-[3, 4-b]benzo[d]thiazoles. Most compounds exhibited good anticonvulsant activity in the Maximal electroshock (MES) test. And the structure-activity relationships (SAR) were analyzed. Among the compounds studied, 7- octyloxy-triazolo-[3, 4-b]benzo[d]thiazole (5g) was found to be the most potent compound with a median effective dose (ED50) value of 8.0 mg/kg and a protective index (PI) value of 15.0, possessing better anticonvulsant activity and higher safety than marketed drugs carbamazepine and phenytoin. The mechanism study of compound 5g showed that it displayed broad spectrum activity in several models, and it is likely to have several mechanisms of action (including inhibiting voltage-gated ion channels and GABAergic activity).

In this paper we report the synthesis and in vitro activity of two new mixed ligand platinum complexes: trans- [PtCl2(thiazole)(imidazole) [JH3] and trans-[PtCl2(thiazole)(3-hydroxypyridine) [JH4]. Although the compounds are less active than cisplatin against the parent ovarian cancer cell line A2780, they are more active than cisplatin against the resistant cell lines A2780cisR and A2780ZD0473R, thus indicating that JH3 and JH4 have been better able to overcome mechanisms of resistance operating in A2780cisR and A2780ZD0473R. When Pt-DNA binding levels at 24 h in A2780, A2780cisR and A2780ZD0473R cell lines are compared it is found that whereas for cisplatin the values in resistant cell lines are significantly lower than that in the parent cell line, for JH3 and JH4 Pt-DNA binding levels in the parent and resistant cell lines are comparable, thus providing an explanation for variations in activity of the compounds in the three cell lines.