Medicinal Chemistry - Volume 10, Issue 5, 2014

Only 10% of all compounds developed by pharmaceutical companies make it to the market. Of the 90% that do not make it to the market, 50% either have toxicity or pharmacokinetic issues. Thus, the need for ADMET (absorption, distribution, metabolism, excretion and toxicity) optimization during the early stages of drug development is clear. In silico tools may be promising for this use due to their lower cost and time requirements. This review aims to evaluate the predictive power of intestinal absorption and oral bioavailability prediction methods using different statistical approaches over time. Improvement, refinement and diversification of these methods have been observed over the past few years. Nevertheless, some elements related to the quality of the biological data, disclosure of the data used and description of validation methods, that could contribute to building new, better and more reliable models have been ignored by researchers or restricted by the technical limitations of various laboratories.

We have recently reported a novel class of selective 5-HT1A agonists among which GF449 emerged for its high potency and almost full agonist activity (pKi 5-HT1A = 8.8; pD2 = 9.22, %Emax = 91.6). In order to quantify GF449 in rat plasma and brain, a sensitive LC-MS/MS method was developed and validated. Solid phase extraction (SPE) or a combined protein precipitation SPE permitted an efficient analyte recovery and sample clean-up. Multiple reaction monitoring (MRM) was used to track both GF449 and its internal standard (IS), MM189. GF449 was determined and quantitated to nanomolar concentrations in both plasma and brain matrix (LOQs = 0.0025 nmol/mL). Specificity was ensured using three further MRM qualifier transitions for both analyte and IS. Linearity was found in the range of 0.0025 nmol/mL to 1.00 nmol/mL (R2 = 0.9965) and from 0.0025 nmol/mL to 50 nmol/mL (R2 = 0.9999) for plasma and brain respectively. Intraday trueness ranged from 94.0% to 117.5% for brain and from 93.7% to 108.1% for plasma, while precision values were within 3.0% - 6.7% and 2.5% - 9.2% for plasma and brain respectively. The interday trueness of plasma ranged from 89.6% to 107.7% and the precision values (CV%) ranged from 4.6% to 7.5%. Interday trueness and precision (CV%) of the brain ranged from 94.3% to 101.2% and from 1.6% to 11.5% respectively. The method was validated in accordance with the EMEA guidelines and was successfully applied to plasma and brain samples obtained from rats treated with a 10 mg/kg single oral dose of GF449, thus demonstrating its applicability to preclinical pharmacokinetic studies.

Pain management is an important medical problem with social and economic consequences. Opioid receptors are among the most important molecular targets involved in antinociception. We have previously reported several series of antinociceptive compounds with the affinity to opioid receptors. In search for novel compounds acting on central nervous system with antinociceptive activity we synthesized a series of 1-aryl-7-hydroxy-2,3-dihydroimidazo[1,2- a]pyrimidine-5(1H)-ones and their 6-phenyl derivatives. The novel compounds were subjected to extensive pharmacological studies to assess their effect on motor coordination, body temperature, clonic seizures and tonic convulsions and their antinociceptive activity. In the writhing test the antinociceptive activity of some derivatives was reversed by naloxone, thus we can assume that their activity may be associated with opioid system. We also used molecular modeling to describe active conformations of the studied compounds and to build a pharmacophore model. As in the previously reported series of the compounds, the studied substances exerted antinociceptive activity probably associated with the opioid system without possessing a protonable nitrogen atom. Furthermore, we calculated structural, electronic and ADMET parameters (volume, surface area, polar surface area, ovality, dipole moment, HOMO and LUMO energies, polarizaibility, molar refractivity, lipophilicity, the charges on the heteroatoms, aqueous solubility, and blood-brain barrier permeation parameter) for novel compounds in order to address the observed structure-activity relationship.

Herein we report a feasible study concerning the design, syntheses and in vitro antimicrobial and antitumoral activities of some novel compounds with dihydroxyacetophenone (DA) moiety. An efficient and general method for the preparation of diazine with dihydroxyacetophenone (DDA) skeleton under conventional thermal heating (TH), microwave (MW) and ultrasounds (US) irradiation is presented. Antimicrobial and antitumoral tests prove that some dihydroxyacetophenone compounds (the brominated derivatives BrDA 3) have a significant biological activity. It is also to be pointed out that, basically all the dihydroxyacetophenone derivatives proved to have a powerful antibacterial activity against drug resistant Gram-negative strain Pseudomonas aeruginosa ATCC 27853. Of particular interest could be the excellent antibacterial activity of our dihydroxyacetophenone compounds against drug resistant Gram-negative strain Pseudomonas aeruginosa.

A series of new 7-piperazinyl and 7-piperidinyl-3,4-dihydroquinazolin-2(1H)-ones has been synthesized. The described compounds are structurally related to adoprazine, a potential atypical antipsychotic bearing potent D2 receptor antagonist and 5-HT1A receptor agonist properties. Suitably modified aryl bromides were prepared and condensed with tert-butyl piperazine-1-carboxylate to afford the advanced intermediate piperazinyl-3,4-dihydroquinazolin-2(1H)-one. Likewise Suzuki-Miyaura cross-coupling reaction of cyclic vinyl boronate with appropriate aryl bromides rendered piperidinyl-3,4-dihydroquinazolin-2(1H)-one. The reductive amination of the piperazinyl and piperidinyl-3,4- dihydroquinazolin-2(1H)-ones with suitably designed biarylaldehydes accomplished the synthesis of these title compounds. The described compounds were screened for D2 and 5-HT1A receptors binding affinities. The structure-activity relationship studies revealed that cyclopentenylpyridine and cyclopentenylbenzyl groups contribute significantly to the dual D2 and 5-HT1A receptor binding affinities of these compounds.

Combined blockade of IKr and IKs potassium channels is considered to be a promising therapeutic strategy for arrhythmia. In this study, we designed and synthesized 15 derivatives through modifying the hit compound 7 that was discovered by screening in-house database by whole-patch clamp technique. All of the compounds were evaluated on CHO and HEK 293 cell lines stably expressing hERG (IKr) and hKCNQ1/KCNE1 (IKs) potassium channels, and half of them exhibited improved dual IKr and IKs inhibitory effects compared to the hit compound. Compounds 7a and 7b with potent dual inhibitory activities were selected for further in vivo evaluations. Due to the preferable pharmacological behaviors, compound 7a deserved further optimization as a promising lead compound.

We have synthesized a series of polyamine-based anilinoacridine derivatives. The preliminary biological evaluation indicated that the 9-anilinoacridine-polyamine derivatives had low or insignificant in vitro cytotoxicity against K562 cell line and K562/ADM, the drug-resistant cell line. However, the evaluation for P-gp modulation showed that they held potent P-gp inhibitory ability. Among them, the effect of compound 7c on P-gp was even greater than that of Verapamil, the known P-gp modulator. The results suggest that 9-anilinoacridine-polyamine derivatives can be employed as effective P-gp modulators.

A series of hitherto unreported piperidone embedded α,β-unsaturated ketones were synthesized efficiently in ionic solvent and evaluated for cholinesterase inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Most of the synthesized compounds displayed good enzyme inhibition; therein compounds 7i and 7f displayed significant activity against AChE with IC50 values of 1.47 and 1.74 μM, respectively. Compound 6g showed the highest BChE inhibitory potency with IC50 value of 3.41 μM, being 5 times more potent than galanthamine. Molecular modeling simulation was performed using AChE and BChE receptors extracted from crystal structure of human AChE and human BChE to determine the amino acid residues involved in the binding interaction of synthesized compounds and their relevant receptors.

The present investigation describes the synthesis of a new series of aldehydo-sugar-N-(3-phenylquinoxalin-2- yl)hydrazones 3a-d and their acyclic C-nucleoside analogs, 1-(4-phenyl-[1,2,4]triazolo[4,3-a]quinoxalin-1-yl)alditols 7ad by using 2-hydrazino-3-phenylquinoxaline 1 as key intermediate. The synthesized compounds were screened for their antioxidant activities by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging method. Compounds 3d and 7a, showed potent scavenging activities against ABTS+ radicals and were found to be the most potent antioxidants described in this study. Out of the synthesized compounds, compounds 3d and 7a were selected by the National Cancer Institute for evaluation of their in vitro anticancer activity. Results revealed that compounds 3d and 7a exhibited non-selective broad spectrum activity against all cancer cell lines between 10-6 to 10-5 molar concentrations. Compound 3d showed the highest sensitivity against leukemia cell line HL-60 (TB) with GI50 of 5.15 μM, while compound 7a showed the highest sensitivity against ovarian cancer cell lines IGROV1 and OVCAR-4 with GI50 of 14.5 and 16.0 μM, respectively. In addition, compounds 3d and 7a showed TGI values of 72.2 and 96.3 μM, respectively against ovarian cancer cell line OVCAR-4. Furthermore, the target compounds were tested for antiviral activity against Herpes Simplex virus type-1 (HSV-1) using plaque reduction infectivity assay. The results indicated that compounds 3a-d and 7a exhibited very weak antiviral activity in comparison to Aphidicolin as a positive control.

Twelve new aryl-substituted naphthalenoids (1-7, 9, 10, and 13-16) together with four known ones (8, and 11- 13) have been designed and synthesized. Their antitumor activities were evaluated by sulforhodamine B assay on human breast cancer MDA-MB-231, human lung cancer A549 and human cervical cancer HeLa cell lines. Four compounds (2, 4, 10 and 12) showed potent inhibitory activities against the growth of the three cell lines with IC50 between 0.34-3.49 μM, and were more potent than the reference etoposide (IC50 3.67-13.78 μM). DNA relaxation assay revealed that compound 2 showed potent inhibitory activity against Topo IIα in vitro. The structure-activity relationships of these compounds were discussed, suggesting that further structural optimizations of aryl-substituted naphthalenoids could lead to the discovery of potent antitumor agents targeting topoisomerases.