Medicinal Chemistry - Volume 3, Issue 5, 2007

During carcinogenesis aberrant N-glycosylation may lead to the development of subpopulations of tumor cells with altered adhesion properties and increased invasive potential. Biosynthesis of glycans and oligosaccharides is tissue- specific and developmentally regulated by number of glycosyltransferases of which fucosyl-, sialyl- and Nacetylglucosaminyltransferases often participate in synthesis of tumor type glycans. We analyzed the expression of selected glycosyltransferases (real-time PCR): fucosyltransferases FUT-1 and FUT-4, sialyltransferase SIAT4C and beta 1,6-N-acetylglucosaminyltransferase V (MGAT-5), in human melanoma cell lines: WM35 from primary tumor site and WM239, WM9, A375 from metastatic sites. In parallel their proliferation (crystal violet test) and adhesion to fibronectin and collagen IV (BD Biocoat assay) was assessed. Examined cell lines showed expression of all studied glycosyltransferases. The level of expression of fucosyltransferases was significantly higher in melanoma cell lines from metastatic site than from primary cell line: mRNA expression of FUT-1 was 100 times higher in A375 melanoma cell line from metastatic site (A375, solid tumor) than in WM35 primary cell line. The expression of FUT-4 in cell lines from metastatic sites: WM9 (lymph node) and WM239 (skin) was respectively 80 and 37 times higher than in WM 35 primary cell line. In all melanoma cell lines very low expression of MGAT-5 and high expression of SIAT4C was observed. Melanoma cells bound both to fibronectin and to collagen IV. LTA (Lotus tetragonolobus agglutinin), the lectin that specifically recognizes fucose residue of glycans and 20mM L-fucose by itself significantly reduced adhesion of all studied cell lines, both primary and metastatic, to fibronectin (20-50 %) and to collagen IV (20-50 %). In addition LTA reduced the proliferation (20-30 %) of metastatic cell lines (A375, WM9, WM239) and did not affect the growth of primary cell line (WM35). The results suggest that higher expression of fucosyltransferases (FUT-1, FUT-4) might be an important step in the formation of surface structures that facilitate metastasis of melanoma.

In the search for effective, selective, and nontoxic antiviral and antitumor agents, a variety of strategies have been devised to design nucleoside analogues. Here we have described the versatile synthesis of β-L-1,3- thiazolidine nucleoside analogues. These analogues are all derived from the key stereochemically defined intermediate Ntert- butoxy-carbonyl-4-hydroxymethyl-1,3-thiazolidine-2-ol which was accessible in 57% yield starting from L-Cysteine methylester hydrochloride. N-tert-butoxycarbonyl-2-acyloxy-4-trityloxymethyl-1,3-thiazolidine was coupled with the pyrimidine bases in the presence of Lewis acids stannic chloride or trimethyl silyl triflate following Vorbruggen procedure. Proof of the structure and configuration was obtained through 1H NMR, 13C NMR, Mass, elemental analysis and NOE experiments. Docking and antitumor activity of these nucleoside analogues are also reported.

The synthesis of a series of 6-aryl-4-oxohexanoic acids is described: This involves condensation of an appropriate aldehyde (Ia-f) and levulenic acid using catalytic amounts of piperidine and acetic acid in toluene to afford the 6- aryl-4-oxohex-5-enoic acids (IIa-f).The arylidene derivatives (IIa-d) were reduced by hydrogen at room temperature using palladium (10 %/carbon) as catalyst to produce 6-aryl-4-oxohexanoic acids (IIIa-d) as target compounds. In certain instances, the lactone derivative (IVd) was obtained as a low-melting by-product. These compounds were tested in two models used for evaluating the activity of non-steroidal anti-inflammatory drugs (NSAIDs). The first test is the effect of the synthesized compounds on arachidonic acid metabolism in vitro using human whole blood assay. The second is the in vivo carrageenan induced rat paw edema test. Compound IIe showed higher in vivo-activity compared to fenbufen at the same dose level (50mg/kg).

Taking into account that compounds bearing a thiazolyl, pyridyl and indolyl, moieties possess a wide spectrum of biological activities which is related to their capacity to transfer electrons and to scavenge reactive oxygen species (ROS), we synthesized some new heterocyclic aryl acetic acids and the corresponding acetohydroxamic acids and we explored their ability to inhibit soybean lipoxygenase, to present antioxidant and anti-inflammatory activities as well as to present serine proteases inhibition. The compounds were found to strongly inhibit lipid peroxidation. and to decrease in vivo the carrageenin induced rat paw edema (28-56%). Compound 1i possesses the highest decrease 56%, in vivo. The tested derivatives presented interesting inhibitory activity on soybean lipoxygenase. Compound 5ii showed significant in vitro inhibition on trypsin (IC50 87μM). The results are discussed in terms of structural and physicochemical characteristics of the compounds. The structures of the synthesized compounds were confirmed by spectral and elemental analysis. Their lipophilicity is experimentally determined by RPTLC method.

7-Methoxy-3-phenyl-4-phenylvinyl benzopyran-2-ones and the corresponding 2,2-dimethyl-benzopyrans, substituted with different alkylamino residues were synthesized. Except compound 13e, all compounds showed high level of estrogen agonistic activity (>81 %) whereas, compounds 13 b-e and 15a showed significant estrogen antagonistic activity (>20 %). X-Ray analysis of a 7-methoxy-3-phenyl-4-phenylvinyl benzopyran-2-one derivative 13d showed its structural resemblance to endogenous estrogen, 17β-estradiol. Estrogenic and antiestrogenic activities of these derivatives demonstrate their estrogen receptor (ER) binding ability. The lack of hydroxyl groups at appropriate positions resulted in poor Relative Binding Affinity (RBA).

West Nile virus (WNV) is a mosquito-borne disease that emerged in North America. In 2002 it caused the largest arboviral meningoencephalitis outbreak ever recorded in the US and Canada. The key enzyme responsible for the replication of the virus is the RNA-dependent RNA polymerase (RdRp) enzyme represented by nonstructural protein NS5 in WNV To understand the structural basis and enzymatic activity of WNV RdRp as well as potential drug susceptibility, we have built a homology model of WNV NS5 RdRp based on a combination of motif search, fold recognition and sequence alignments orchestrated by 3D-jury system. We have located conserved sequence motifs shared by all RdRps and described the potential functional role of these motifs and specific residues in the polymerization and in the recognition of potential inhibitors. Virtual docking of several substrates and inhibitors in our WNV RdRp model shows that a non-nucleoside inhibitor such as 2'-methyl-ribofuranosyl-guanosine triphosphate has a higher binding energy indicated by a low free energy obtained upon binding. These results provide a preliminary basis for the development of anti-WNV agents based on RNA dependant RNA polymerase inhibition.

This study describes the design, synthesis and trypanocidal evaluation of new azaheterocyclic derivatives (4-8). These compounds were designed as megazol (1) analogs based on bioisosterism tools and were synthesized to investigate the possible pharmacophoric contribution of the 1,2,4-triazole nucleus, the position of the heterocyclic nucleus and presence of the nitro group, to the activity against the bloodstream trypomastigote forms of Trypanosoma cruzi. The most potent compound was 6, a nitro derivative obtained by substitution of a thiadiazole by a triazole ring and by moving the nitro group from C-5 position, as in 1, to the C-4 position. Finally, we have used semi-empirical theoretical calculations to discuss the correlation of some stereo electronic properties with biological activity in an attempt to understand the possible mechanism of action of the designed series of compounds.

The new germanium compounds of cinnamic acid, RC6H4CHGe(OCH2CH2)3NCH2COOH R=H (I), 2-OH (II), 3-OH (III), 4-OH (IV), have been obtained to study anti-tumor activities. Compounds (I-IV) were prepared by the electrophilic addition reaction and nucleophilic substitution reaction. Biological investigation has demonstrated that all compounds (I-IV) are lower toxicity with strongly anti-tumor activity than positive control.

Non-transferrin-bound iron (NTBI) is detectable in plasma of β-thalassemia patients with transfusional iron overload. This form of iron may cause oxidative tissue damage and increased iron uptake, into several vital organs. Removal of NTBI species is incomplete and transient using standard intermittent desferrioxamine (DFO) or deferiprone (DFP) monotherapy. Combinations of these or other chelators may improve the protection time from NTBI and increase removal of harmful NTBI species. Curcuminoids from Curcuma longa L. is a naturally occurring phytochemical which shows a wide range of pharmacological properties including anti-oxidative, anti-inflammatory, anti-cancer and ironchelating activities. In this study, the curcuminoids was investigated for NTBI chelation in thalassemic plasma in vitro and for the potential to improve NTBI removal when used with other chelators. Curcumin bound Fe3+ to form a Fe3+-curcumin complex with a predominant absorption at 500 nm. The chemical binding of curcumin was dose- and time-dependent and more specific for Fe3+ than Fe2+. Using a HPLC-based NTBI assay without an aluminium blocking step, curcumin shuttled the iron from Fe3+-NTA complex, giving underestimated NTBI values. At equivalent concentrations DFO, DFP and curcumin decreased plasma NTBI with the order of DFP>DFO>curcumin. None of these chelators removed NTBI completely, but curcumin appeared to increase the rate of NTBI removal when added to DFP. It is proposed that the β-diketo moiety of curcumin participates in the NTBI chelation.

Among various phenolic compounds, caffeic acid (3,4-dihydroxycinnamic acid) exhibited pharmacological antioxidant, anticancer and antimutagenic activities. The antioxidant properties of phenolic compounds depend on their chemical structure, however, the role of the ethylenic side chain in the radical scavenging activity remains controversial. Thus, the aim of this study consisted to test cinnamic acid and 15 cinnamic acid derivatives in the well known CCl4- induced acute liver damage model, which is dependent on oxidative stress mechanisms. Cinnamic acid and 15 cinnamic acid derivatives (50 mg/kg, p.o.) were administered to male Wistar rats intoxicated with CCl4 (4 g/kg, p.o.). The activities of gamma-glutamyl transpeptidase, alkaline phosphatase and alanine aminotransferase were measured in serum. The lipid peroxidation products were determined in liver. Compounds with a methoxy group at position 3 or 4, or a 3,4- methylenedioxy moiety were the most active ones. Also, we observed that the monosubstituted 3 or 4 hydroxy, or the bulky 3,4 dibenzyloxy substituted compounds showed lower activity. The poorest activity was displayed by disubstituted 3,4-dihydroxy, dimethoxy or diacetyl cinnamic acid derivatives, the ester derived from cinnamic acid with an 8 carbon chain and N-dimethyl substituted compound. Thus, the methoxy substituted group at positions 3 or 4 or the 3,4- methylenedioxy moiety in the caffeic acid derivatives; seem to be the main features required for the hepatoprotection in this model.

Endogenous opioids have been studied extensively since their discovery, in the hope of findings a perfect analgesic, devoid of the secondary effects of alkaloid opioids. However, the design of selective opioid agonists and or antagonists has proved very difficult. First, structural studies of peptides in general are hampered by their intrinsic flexibility. Second, the relationship between constitution and the socalled “bioactive conformations” is far from obvious. Ideally, a direct structural study of the complex between a peptide and its receptor should answer both questions, but such a study is not possible, because opioids receptors are large membrane proteins, difficult to study by standard structural techniques. Thus, conformational studies of opioid peptides are still important for drug design and also for indirect receptor mapping. This review deals the pharmacological activity of : a) a new μ and δ agonist: The single amino acid replacement of 2',6'-dimethyl-L-tyrosine in deltorphin B (H-Dmt-DAla- Phe-Glu-Val-Val-Gly-NH2) yielded high affinity for mu- and delta-binding sites. [Dmt1]Deltorphin B lacks activity at kappa-opioid binding sites. Bioactivity in vitro with guinea-pig ileum confirmed that [Dmt1]deltorphin B interacted with mu-opioid receptors by reducing electrically induced contractions in a naloxone-reversible manner and was 150-fold more potent than morphine and comparable to [D-Ala2,NMePhe4,Gly-ol5]enkephalin (DAGO). The inhibition of spontaneous contractions of rabbit jejunum provided evidence for delta-opioid receptor interaction. Analgesia (hot plate and tail flick tests) revealed that [Dmt1]deltorphin B was 180- to 200-fold more potent than morphine. Pretreatment with naloxone, naltrindole or H-Dmt-Tic-Ala-OH (a highly selective delta-opioid receptor antagonist) prevented [Dmt1]deltorphin B antinociception. Thus, [Dmt1]deltorphin B exhibited remarkably high dual affinity and bioactivity toward deltaand mu-opioid receptors. b) two new δ opioid peptide receptor antagonists (Dmt-Tic-OH (DTOH) and Dmt-Tic-Ala-OH (DTAOH): Dmt-Tic- OH (DTOH) and Dmt-Tic-Ala-OH (DTAOH), effective antagonists in vitro, represent a new potent opioid dipeptides for the delta-opioid receptor (Ki delta of 0.022 nM and a selectivity, Ki mu/Ki delta, of 150,000 for DTOH; Ki delta of 0.285 nM and a selectivity Ki mu/Ki delta, of 20,4 for DTAOH). In the present study we considered the pharmacological activity of these two new delta opioid peptide receptor antagonists in vivo. Therefore, we have evaluated their possible antagonistic activity against the antinociception induced by the highly selective delta opioid receptor agonist, [D-Ala2]deltorphin II (DEL). Furthermore, these two delta opioid peptide receptor antagonists were injected centrally or peripherally in order to assess their ability to act also after systemic administration. Concurrent i.c.v. injection of DTOH or DTAOH (0.5-1.0- 2.0 nM) with DEL (5 nmol) induced a significant reduction of DEL antinociception. By contrast, while DTOH (10-20-40 mg/kg) administered peripherally (i.p., s.c. or i.v.) was also able to reduce DEL antinociception, DTAOH failed. The present results indicate that DTOH is the first opioid dipeptide with delta antagonist activity after systemic administration and it could be important in the clinical and therapeutic applications. c) a new μ selective opioid dipeptide antagonists: the potent delta selective opioid antagonist dipeptides were designed on the basis of a simple conformational analysis. Following a similar procedure we found a mu selective dipeptide antagonist, 2,6-dimethyl-Tyr-D-Phe-NH2. Although its selectivity is not as high as those of the quoted delta selective dipeptides it has good in vitro activity and looks very promising for further development since the 2,6-dimethyl-Tyr-D-Phe message, like the delta selective 2,6-dimethyl-Tyr-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid counterpart, seems able to impart antagonism to longer peptides.

To find new drug candidates for treating Alzheimer's disease, we used the similarity search technique and GTS-21 as a template to search the Traditional Chinese Medicines Database. The high-score molecules thus obtained were compared with the template through the flexible alignment. Those molecules which had good alignment with GTS- 21 were selected for conducting the docking studies aimed at the α7 nicotinic acetylcholine receptor. The CHARMM22 force field was taken to compute the partial charge and the TABU search was adopted to operate the docking process. The docking results thus obtained were used to compare with that of GTS-21. Those molecules which had better docking results than that of GTS-21 were singled out for further consideration. Finally, it was found through an in-depth structural analysis that Mol 7235 might be a promising candidate for further modification by experiments to make it become an effective drug for treating Alzheimer's disease.

Glucocorticoids are four-ring steroid compounds that regulate a wide range of physiological systems ranging from embryonic respiratory development, immune function and responses to acute or chronic stress. Glucocorticoids are taken up by many target cells where they bind and activate cytoplasmic glucocorticoid receptors (GRs), which then dimerize, translocate to the nucleus and function as ligand-dependent transcriptional regulators. Synthetic glucocorticoids such as dexamethasone and prednisolone have for decades been the cornerstone for the clinical treatment of inflammatory diseases, such as rheumatoid arthritis and asthma, yet prolonged use have undesirable side-effects such as persistent immune suppression, metabolic imbalance, obesity, diabetes, and osteoporosis. Detailed understanding of the cell signaling mechanisms of GR action has led to the development of novel selective glucocorticoid receptor ligands that appear to offer more efficient treatments for a number of diseases while eliciting fewer side-effects. Additionally, in cell-based and animal model systems a number of compounds such as the methane sulphonamides and a novel compound A-348441 have shown promise as GR antagonists. Other classes of ligands such as the benzopyranoquinolines and the arylpyrazoles have further been shown to selectively influence the transcriptional regulatory properties of GRs on different target gene in various cellular contexts. These selective GR modulators are believed to initiate transcriptional co-regulator recruitment that in turn promotes specific gene responses relevant to the more efficient and specific treatment of inflammatory conditions and metabolic diseases such as type-2 diabetes.