Synthesis of some novel orsellinates and lecanoric acid related depsides as α-glucosidase inhibitors

Sixteen novel orsellinic esters (6a-l, 7a-d) along with four lecanoric acid related depsides (3a-c, 4) were synthesized and confirmed their structures by spectroscopic data (¹H, ¹³C & HRMS). The synthesized compounds were evaluated for their in vitro α-glucosidase (Saccharomyces cerevisiae) inhibitory potential. Among the tested compounds, 3c (IC₅₀: 140.9 μM) and 6c (IC₅₀: 203.9 μM) displayed potent α-glucosidase inhibitory activity and found more active than the standard drug acarbose (IC₅₀: 686.6 μM). Both the test compounds were subjected to in vivo antihyperglycemic activity using sucrose loaded model in Wistar rats and found compound 3c exhibited significant reduction in glucose levels.

Synthesis of NSC 106084 and NSC 14778 and evaluation of their DNMT inhibitory activity

DNA methylation is an epigenetic modification that is performed by DNA methyltransferases (DNMTs) and that leads to the transfer of a methyl group from S-adenosylmethionine (SAM) to the C5 position of cytosine. This transformation results in hypermethylation and silencing of genes such as tumor suppressor genes. Aberrant DNA methylation has been associated with the development of many diseases, including cancer. Inhibition of DNMTs promotes the demethylation and reactivation of epigenetically silenced genes. NSC 106084 and 14778 have been reported to inhibit DNMTs in the micromolar range. We report herein the synthesis of NSC 106084 and 14778 and the evaluation of their DNMT inhibitory activity. Our results indicate that while commercial NSC 14778 is moderately active against DNMT1, 3A/3L and 3B/3L, resynthesized NSC 14778 is inactive under our assay conditions. Resynthesized 106084 was also found to be inactive.

Synthesis and Biological Evaluation of Cajaninstilbene Acid and Amorfrutins A and B as Inhibitors of the Pseudomonas aeruginosa Quorum Sensing System

The quorum sensing (QS) system inhibitors of Pseudomonas aeruginosa are thought to attenuate bacterial pathogenicity and drug resistance by inhibiting biofilm formation and the production of virulence factors. In this study, a synthetic approach to the natural products cajaninstilbene acid (1) and amorfrutins A (2) and B (3) has been developed and was characterized by the Heck reaction, which was used to obtain the stilbene core and a Pinick oxidation to give the O-hydroxybenzoic acid. The biological activities of these compounds against the P. aeruginosa quorum sensing systems were evaluated. Amorfrutin B (3) showed promising antibiofilm activity against P. aeruginosa PAO1 with a biofilm inhibition ratio of 50.3 ± 2.7. Three lacZ reporter strains were constructed to identify the effects of compound 3 on different QS systems. Suppression efficacy of compound 3 on the expression of lasB-lacZ and pqsA-lacZ as well as on the production of their corresponding virulence factors elastase and pyocyanin was observed.

A prodrug micellar carrier assembled from polymers with pendant farnesyl thiosalicylic acid moieties for improved delivery of paclitaxel

In order to achieve enhanced and synergistic delivery of paclitaxel (PTX), a hydrophobic anticancer agent, two novel prodrug copolymers, POEG15-b-PFTS6 and POEG15-b-PFTS16 composed of hydrophilic poly(oligo(ethylene glycol) methacrylate) (POEG) and hydrophobic farnesylthiosalicylate (FTS, a nontoxic Ras antagonist) blocks, were synthesized. Both POEG-b-PFTS polymers were able to form micelles with intrinsic antitumor activity in vitro and in vivo. Employing these micelles as a carrier to load PTX, their drug loading capacity, stability, in vivo biodistribution and tumor inhibition effect were evaluated. PTX/POEG15-b-PFTS16 mixed micelles exhibited an excellent stability of 9days at 4°C with a PTX loading capacity of 8.2%, which was more effective than PTX/POEG15-b-PFTS6 mixed micelles. In vivo biodistribution data showed that DiR-loaded POEG-b-PFTS micelles were more effectively localized in the tumor than in other organs. Moreover, both PTX/POEG-b-PFTS micelles showed significantly higher antitumor activity than Taxol in a 4T1.2 murine breast tumor model, and the tumor inhibition and animal survival followed the order of PTX/POEG15-b-PFTS16>PTX/POEG15-b-PFTS6>POEG15-b-PFTS16>Taxol≈POEG15-b-PFTS6. Our data suggest that POEG-b-PFTS micelles are a promising anticancer drug carrier that warrants more studies in the future.

STATEMENT OF SIGNIFICANCE

Polymerization of drug-based monomer represents a facile and precise method to obtain well-defined polymeric prodrug amphiphiles. Currently, most reports largely focus on the synthesis methods and the biophysical properties. There is limited information about their anti-tumor activity and delivery function as prodrug carriers in vitro and in vivo. In this manuscript, we report the development of two novel prodrug copolymers, POEG15-b-PFTS6 and POEG15-b-PFTS16 composed of hydrophilic poly(oligo(ethylene glycol) methacrylate) (POEG) and hydrophobic farnesylthiosalicylate (FTS, a nontoxic Ras antagonist) blocks. Both POEG-b-PFTS polymers were able to self-assemble into nano-sized micelles with intrinsic antitumor activity in vitro and in vivo. More importantly, POEG-b-PFTS polymers were effective in forming stable mixed micelles with various anticancer agents including PTX, DOX, docetaxel, gefitinib, and imatinib. Delivery of PTX via our new carrier led to significantly improved antitumor activity, suggesting effective PTX/FTS combination therapy. We believe that our study shall be of broad interest to the readers in the fields of biomaterials and drug delivery.

Computational and synthetic approaches for developing Lavendustin B derivatives as allosteric inhibitors of HIV-1 integrase

Through structure-based virtual screening and subsequent activity assays of selected natural products, Lavendustin B was previously identified as an inhibitor of HIV-1 integrase (IN) interaction with its cognate cellular cofactor, lens epithelium-derived growth factor (LEDGF/p75). In order to improve the inhibitory potency we have employed in silico-based approaches. Particularly, a series of new analogues was designed and docked into the LEDGF/p75 binding pocket of HIV-1 IN. To identify promising leads we used the Molecular Mechanics energies combined with the Generalized Born and Surface Area continuum solvation (MM-GBSA) method, molecular dynamics simulations and analysis of hydrogen bond occupancies. On the basis of these studies, six analogues of Lavendustine B, containing the benzylamino-hydroxybenzoic scaffold, were selected for synthesis and structure activity-relationship (SAR) studies. Our results demonstrated a good correlation between computational and experimental data, and all six analogues displayed an improved potency for inhibiting IN binding to LEDGF/p75 in vitro to respect to the parent compound Lavendustin B. Additionally, these analogs show to inhibit weakly LEDGF/p75-independent IN catalytic activity suggesting a multimodal allosteric mechanism of action. Nevertheless, for the synthesized compounds similar profiles for HIV-1 inhibition and cytoxicity were highlighted. Taken together, our studies elucidated the mode of action of Lavendustin B analogs and provided a path for their further development as a new promising class of HIV-1 integrase inhibitors.

Synthesis, characterization and oscillator-vibrated near-infrared (NIR) luminescence of two pseudo-polymorphic [Yb4((OH)2-Salophen)4] complexes

Through the self-assembly of the (OH)2-Salophen H4L (H4L=N,N'-bis(3-hydroxylsalicylidene)benzene-1,2-diamine) with LnCl3·6H2O or Ln(NO3)3·6H2O (Ln=La, Yb or Gd) in different solvent systems MeCN-EtOH and MeCN-DMF, the mixed (L)(4-) and (H2L)(2-) coordination modes induce the formation of anion-independent while pseudo-polymorphic homoleptic linear tetranuclear complexes [Ln4(H2L)2(L)2(EtOH)2] (Ln=La, 1; Ln=Yb, 2 or Ln=Gd, 3) and [Ln4(H2L)2(L)2(DMF)2] (Ln=La, 4; Ln=Yb, 5 or Ln=Gd, 6), respectively. The result of their photophysical properties shows the characteristic NIR luminescence for both Yb(3+)-based complexes 2 and 5 with emissive lifetimes in microsecond ranges, while the difference of nearby and/or distant oscillator-based (OH and/or CH) vibrations from two coordinated EtOH or DMF molecules within the inner coordination spheres of Yb(3+) ions in the two complexes has a decisive effect on their NIR luminescent properties.

General method for the synthesis of salicylic acids from phenols through palladium-catalyzed silanol-directed C-H carboxylation

A silanol-directed, palladium-catalyzed C-H carboxylation reaction of phenols to give salicylic acids has been developed. This method features high efficiency and selectivity, and excellent functional-group tolerance. The generality of this method was demonstrated by the carboxylation of estrone and by the synthesis of an unsymmetrically o,o'-disubstituted phenolic compound through two sequential C-H functionalization processes.

Microwave assisted synthesis and biomedical potency of salicyloyloxy and 2-methoxybenzoyloxy androstane and stigmastane derivatives

A convenient microwave assisted solvent free synthesis as well as conventional synthesis of salicyloyloxy and 2-methoxybenzoyloxy androstane and stigmastane derivatives 7-19 from appropriate steroidal precursors 1-6 and methyl salicylate is reported. The microwave assisted synthesis in most cases was more successful regarding reaction time and product yields. It was more environmentally friendly too, compared to the conventional method. The antioxidant activity and cytotoxicity of the synthesized derivatives were evaluated in a series of in vitro tests, as well as their inhibition potency exerted on hydroxysteroid dehydrogenase enzymes (Δ(5)-3βHSD, 17βHSD2 and 17βHSD3). All of the tested compounds were effective in OH radical neutralization, particularly compounds 9, 11 and 14, which exhibited about 100-fold stronger activity than commercial antioxidants BHT and BHA. In DPPH radical scavenging new compounds were effective, but less than reference compounds. 2-Methoxybenzoyl ester 10 exhibited strong cytotoxicity against MDA-MB-231 cells. Most compounds inhibited growth of PC-3 cells, where salicyloyloxy stigmastane derivative 15 showed the best inhibition potency. Compounds 9, 10 and 11 were the best inhibitors of 17βHSD2 enzyme. X-ray structure analysis and molecular mechanics calculations (MMC) were performed for the best cytotoxic agents, compounds 10 and 15. A comparison of crystal and MMC structures of compounds 10 and 15 revealed that their molecules conformations are stable even after releasing of the influence of crystalline field and that the influence of crystal packing on molecular conformation is not predominant.

Synthesis of 3-farnesyl salicylic acid, a novel antimicrobial from Piper multiplinervium

Both 3-farnesyl salicylic acid and 3-geranyl salicylic acid were synthesized from 2,6-dibromophenol and showed low levels of antimicrobial activity against E. coli strains.

Novel chemical synthesis of ginkgolic acid (13:0) and evaluation of its tyrosinase inhibitory activity

A novel efficient synthesis of ginkgolic acid (13:0) from abundant 2,6-dihydroxybenzoic acid was successfully developed through a state-of-the-art palladium-catalyzed cross-coupling reaction and catalytic hydrogenation with an overall yield of 34% in five steps. The identity of the synthesized ginkgolic acid (13:0) was confirmed by nuclear magnetic resonance, mass spectrometry, infrared, and high-performance liquid chromatography. The reaction sequence of this method can be readily extended to the synthesis of other ginkgolic acids. The synthesized ginkgolic acid (13:0) exhibited promising anti-tyrosinase activity (IC₅₀ = 2.8 mg/mL) that was not correlated to antioxidant activity as probed by 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ferric reducing ability of plasma, and oxygen radical absorbance capacity assays. The synthetic strategy developed in this work will significantly facilitate biological studies of ginkgolic acids that have great potential applications in food and pharmaceuticals.

Polyfluorinated Pd(II)-3,5-di-tert-butylsalicylaldimenes complexes: synthesis, structure, spectroscopy, redox behaviors and catalytic activity

A series of new polyfluorinated palladium(II) complexes (7-12) of N-polyfluorophenyl-3,5-di-tert-butylsalicylaldimines (1-6) have been synthesized. They were characterized by analytical, spectroscopic (UV/Vis, IR, (1)H NMR, and ESR), electrochemical methods and their chemical oxidation and hydrogenation catalytic activity were studied. The X-ray crystal structure analysis of bis[N-(3,5-di-tert-butylsalicylidene)-F5Ph]Pd(II) (12) revealed a slightly distorted square-planar trans-PdN2O2 geometry around the palladium center. The UV/Vis and EPR results indicate that chemical oxidation of 7-10 by Ce(IV) in CHCl3 generates relatively stable Pd(II)-phenoxyl radical complexes (g=2.0044-2.0062). The results of chemical and electrochemical oxidation of 1-12, as well as the catalytic activity of 7-10 complexes in the hydrogenation of PhNO2 were presented.

[Salicylic acid derivatives as simplified and novel GK small molecule activators]

Glucokinase (GK) is a new target for the treatment of type II diabetes mellitus (T2DM). In order to find a structure-simplified small molecule GK activator, 19 salicylic acid derivatives were designed and synthesized based on new lead compound (1). Experimental results showed that the potency of compound 8h is superior to control RO-28-0450 in GK activation.

Anacardic acid derived salicylates are inhibitors or activators of lipoxygenases

Lipoxygenases catalyze the oxidation of unsaturated fatty acids, such as linoleic acid, which play a crucial role in inflammatory responses. Selective inhibitors may provide a new therapeutic approach for inflammatory diseases. In this study, we describe the identification of a novel soybean lipoxygenase-1 (SLO-1) inhibitor and a potato 5-lipoxygenase (5-LOX) activator from a screening of a focused compound collection around the natural product anacardic acid. The natural product anacardic acid inhibits SLO-1 with an IC(50) of 52 μM, whereas the inhibitory potency of the novel mixed type inhibitor 23 is fivefold enhanced. In addition, another derivative (21) caused non-essential activation of potato 5-LOX. This suggests the presence of an allosteric binding site that regulates the lipoxygenase activity.

Total synthesis and biological evaluation of transvalencin Z

The emerging global epidemic of drug-resistant tuberculosis has created an urgent need to identify novel therapeutic approaches for disease treatment. Transvalencin Z (1) is a natural product from Nocardia transvalensis with relatively potent and selective antimycobacterial activity against Mycobacterium smegmatis, making it an attractive target for structure-activity and mechanism of action studies. The total synthesis of the four possible diastereomers of transvalencin Z was completed (1a-d), and the absolute configurations were defined using chemical synthesis, HPLC retention times, and optical rotation measurements. Surprisingly, none of the transvalencin Z diastereomers exhibited any inhibitory activity against a panel of microbial pathogens, including several species of mycobacteria.

Synthesis and anti-nociceptive and anti-inflammatory effects of gaultherin and its analogs

The synthesis of gaultherin (1) and its analogs was carried out to provide 11 glycosides under phase-transfer catalytic conditions. The activities of all synthesized compounds were evaluated by nitric oxide production inhibitory assay in vitro. Methyl 2-O-(4-O-β-d-galactopyranosyl)-β-d-glucopyranosylbenzoate (5f) showed significantly anti-nociceptive and anti-inflammatory effects by the evaluation in vivo. Structure-activity relationships within these compounds were discussed.

A Novel Prodrug of Salicylic Acid, Salicylic Acid-glycylglycine Conjugate, Utilizing the Hydrolysis in Rabbit Intestinal Microorganisms

The hydrolysis of salicylic acid-glycylglycine conjugate (salicyl-glycylglycine) following oral, intravenous, intracaecal and rectal administration (434, 72, 36 and 36 μmol kg−1, respectively: equivalent to salicylic acid) was examined in rabbits to develop a novel prodrug of salicylic acid. Salicylic acid was detected in the blood 2 h after oral administration of salicyl-glycylglycine and it reached a maximum level (55·6 μg mL−1) at 15 h, whereas a small amount of salicyl-glycylglycine was found in the blood. In contrast, unchanged salicyl-glycylglycine was found mainly in the blood following its intravenous administration, suggesting the involvement of presystemic deconjugation in the hydrolysis of salicyl-glycylglycine. Immediate and very extensive salicyclic acid formation in the caecum was observed following intracaecal administration of salicyl-glycylglycine, suggesting that the intestinal microorganisms were responsible for the biotransformation of this compound. In-vitro incubation of salicyl-glycylglycine with caecal content showed that salicyl-glycylglycine was hydrolysed efficiently in the caecum. Consequently, the blood concentration of salicylic acid was prolonged extensively following rectal administration of salicylglycylglycine, indicating the usefulness of salicyl-glycylglycine as a prodrug of salicylic acid.

Development of a Prodrug of Salicylic Acid, Salicylic Acid-l-alanine Conjugate, Utilizing Hydrolysis by Rabbit Intestinal Microorganisms

The hydrolysis of salicylic acid-l-alanine conjugate (salicyl-l-alanine) following oral, intravenous, intracaecal and rectal administration (60, 10, 5 and 5 mg kg−1, respectively: salicylic acid equivalent) was examined in rabbits. Salicylic acid was detected in the blood 2 h after oral administration of salicyl-l-alanine and reached a maximum concentration at 10 h, whereas salicyl-l-alanine was rapidly eliminated. In contrast, unchanged salicyl-l-alanine only was found following intravenous administration of salicyl-l-alanine, suggesting that presystemic de-conjugation of salicyl-l-alanine was involved. The intestinal mucosal de-conjugation of salicyl-l-alanine was not recognized in the in-situ intestinal sac preparation with complete mesenteric venous blood collection. Immediate and very extensive salicylic acid formation in the caecum was found following intracaecal administration of salicyl-l-alanine. After oral pretreatment of rabbits with kanamycin sulphate, a significant inhibition of salicylic acid formation following intracaecal administration of salicyl-l-alanine was observed, indicating that the intestinal microorganisms were responsible for the biotransformation of salicyl-l-alanine. In-vitro incubation of salicyl-l-alanine with gut contents showed that the major source of its hydrolysis was the hind gut. Consequently, the blood concentration of salicylic acid was prolonged extensively following rectal administration of salicyl-l-alanine, suggesting the usefulness of salicyl-l-alanine as a prodrug of salicylic acid.

[Immunomodulating activity of chitosan derivatives with salicylic acid and its fragments]

A study of biological activity of the derivatives of the chitin-chitosan oligomer with salicylic acid and its fragments showed that chitosan salicylate actively protected potato tubers against Phytophthora infestans but sharply inhibited reparation of potato tissues. N-(2-Hydroxybenzyl)chitosan exhibited good protective properties but did not influence wound reparation. N-(2-Hydroxy-3-methoxybenzyl)-N-pyridox-chitosan, which contained the pyridoxal and 2-hydroxy-3-methoxy fragments, was the most efficient, stimulating both defense against late blight and wound reparation in potato tissues.

Synthesis and characterization of thiosalicylic acid stabilized gold nanoparticles

We report the synthesis of photoluminescent Au nanoparticles of varying sizes stabilized with a carboxylate group terminated aromatic thiol, thiosalicylic acid. The formation of Au nanoparticles and its stabilization with the thiol has been characterized by different spectroscopic and thermal methods. The water solubility, along with the low degree of aggregation and photoluminescence, enhances their suitability for biological applications. The photoluminescence may be due to charge transfer of the Au core with the stabilizing ligand.

Binuclear ruthenium(III) Schiff base complexes bearing N(4)O(4) donors and their catalytic oxidation of alcohols

An interesting series of binuclear ruthenium(III) Schiff base complexes bearing bis-salophen/bis-naphophen units of the general composition [(EPh(3))(X)Ru-L-Ru(X)(EPh(3))] (where E=P or As; X=Cl or Br; L=binucleating dianionic tetradentate ligands) have been synthesized and characterized by analytical (elemental analysis, magnetic susceptibility measurements), spectral (FT-IR, UV-vis and EPR) and electrochemical methods. These ruthenium(III) complexes have two N(2)O(2) metal binding sites, which are linked to each other with a biphenyl bridge and acts as potential catalyst for oxidation of wide range of primary and secondary alcohols to corresponding aldehydes or ketones with moderate to high conversion in the presence of N-methylmorpholine-N-oxide (NMO). The formation of high-valent Ru(V)=O species as a catalytic active intermediate is proposed for the catalytic processes.

Synthesis, spectroscopy, X-ray structure and redox behaviors of 4-(N-R-salicylideneimine)-2,6-diphenylphenols

A series of sterically hindered 4-(N-R-salicylaldimine)-2,6-diphenylphenols (X), where R=H (1), 3-CH3 (2), 5-CH3 (3), 3-OCH3 (4), 4-OCH3 (5), 5-OCH3 (6), 3-tBu (7), 5-tBu (8), 3,5-tBu2(9) and 5,6-benzo(10), were synthesized and their structure as well as redox behavior studied by analytical, spectroscopic [1H, (13C) NMR, IR, UV-vis and mass spectrometry] and cyclic voltammetric (CV) techniques. Single crystal X-ray diffraction studies of 7 evidenced its existence as non-planar enol-imine tautomer structure, in which the phenol ring of the molecule is twisted around C-N single bond by 21.5(2) degrees. The packing structure of 7 is stabilized by C-H...pi(Ph) and O...O and C...O intermolecular short contact interactions. The CV of X display rate is dependent on irreversible and quasi-reversible redox waves in the anodic and cathodic regions due to oxidation and reduction of phenolic and iminic groups, respectively. As evidenced by ESR and UV-vis study, chemical oxidation of X by PbO2 and (NH4)2Ce(NO3)6 in MeCN and CHCl3 generates stable phenoxyl radicals [(g approximately 2.005 and lambda approximately 450 nm (1600-8200 M(-1) cm(-1))].

Mono- and disalicylic acid derivatives: PTP1B inhibitors as potential anti-obesity drugs

A series of compounds containing one or two salicylic acid moieties were synthesized, and their efficacy to inhibit the phosphohydrolase activity of PTP1B examined. Some of the methylenedisalicylic acid derivatives were potent inhibitors of PTP1B. Of those derivatives, 3c exhibited about a 14-fold selectivity against TC-PTP, and this compound was tested in a mouse model for its efficacy to prevent diet-induced obesity. It effectively suppressed the increases in body weight and adipose mass, without any noticeable toxic effect. The compound also prevented increases in the plasma triglyceride, cholesterol, and nonesterified fatty acid concentrations; thus, expanding its therapeutic potential to other related metabolic diseases, such as hyperlipidemia and hypercholesterolemia.

Efficient Synthesis of Salicylates by Catalytic [3 + 3] Cyclizations of 1,3-Bis(silyl enol ethers) with 1,1,3,3-Tetramethoxypropane

Salicylic acid derivatives were prepared by Me3SiOTf-catalyzed [3 + 3] cyclization of 1,3-bis(silyl enol ethers) with 1,1,3,3-tetramethoxypropane.

Effect of subinhibitory concentration of some established and experimental antifungal compounds on the germ tube formation in Candida albicans

The influence of subinhibitory concentrations of six established and 19 newly synthesized antifungal compounds on the dimorphic transition of three C. albicans strains was evaluated in the filamentation-inducing medium. Amphotericin B was found to produce almost complete inhibition in the germination at a concentration of 1/10 of the corresponding MIC and partial inhibition at a concentration as low as MIC/50. Flucytosine and four azole derivatives were proven ineffective. From the newly synthesized drugs, the incrustoporin derivative LNO6-22, two phenylguanidine derivatives (PG15, PG45), and four thiosalicylanilide derivatives, in particular, showed results comparable to those of amphotericin B, with a high inhibition of germ tube formation at concentrations of MIC/10. In general, concentrations of MIC/50 had no visible effect.

Regioselective Synthesis of 5-Alkylsalicylates, 5-Alkyl-2-hydroxy-acetophenones, and 5-Alkyl-2-hydroxy-benzophenones by [3 + 3] Cyclization of 1,3-Bis(silyl enol ethers) with 2-Alkyl-1,1,3,3-tetraethoxypropanes

A variety of 5-alkylsalicylates, 5-alkyl-2-hydroxy-acetophenones, and 5-alkyl-2-hydroxy-benzophenones was regioselectively prepared by TiCl4 mediated formal [3 + 3] cyclization of 1,3-bis(silyl enol ethers) with 2-alkyl-1,1,3,3-tetraethoxypropanes.

Thiosemicarbazones of Formyl Benzoic Acids as Novel Potent Inhibitors of Estrone Sulfatase

Thiosemicarbazones of the microbial metabolite madurahydroxylactone, a polysubstituted benzo[a]naphthacenequinone, have been previously reported by us as potent nonsteroidal inhibitors of the enzyme estrone sulfatase (cyclohexylthiosemicarbazone 1, IC50 0.46 microM). The active pharmacophore of 1 has now been identified to be 2-formyl-6-hydroxybenzoic acid cyclohexylthiosemicarbazone (25, IC50 4.2 microM). The active partial structure was derivatized in the search for novel agents against hormone-dependent breast cancer. Further substantial increases in activity were achieved by reversal of functional groups leading to the cyclohexylthiosemicarbazones of 5-formylsalicylic acid (35, IC50 0.05 microM) and 3-formylsalicylic acid (34, IC50 0.15 microM) as the most potent analogues identified to date. Both compounds were shown to be noncompetitive inhibitors of estrone sulfatase with Ki values of 0.13 microM and 0.12 microM, respectively. The compounds showed low acute toxicity in the hen's fertile egg screening test.

Methylenedisalicylic acid derivatives: New PTP1B inhibitors that confer resistance to diet-induced obesity

Methylenedisalicylic acid derivatives were synthesized and their inhibitory activities against protein tyrosine phosphatases (PTPases) examined. Two of the compounds, 8 and 9, showed K(i) values of 9.4 and 6.3microM against PTP1B, 4- and 7-fold lower values compared to those against TC-PTP. They were reversible and slow-binding inhibitors against PTP1B. When compound 8 was fed to a mouse model, the weight gain and adipocyte fat storage induced by a high-fat-diet were significantly suppressed.

[Synthesis and bioactivies of salicylic acid-g-chitosan derivatives]

To prepare the derivatives of salicylic acid-g-chitosan and study their synergistic and complementary actions, the synergism of anti-inflammatory action of the derivatives was investigated with the experiments of xylene-induces mice ear edema, the analgesic activities by the tartaric emetic-induced mice twist test and the hot-plate test, and the complementary effects between salicylic acid and chitosan through morphological changes of stomach mucous membrane of rat, separately. The anti-inflammatory activities of salicylic acid-g-chitosan derivatives for anti-inflammatory activities were more potent than that of salicylic acid and chitosan and dexamethasone cream in external use, and more potent than that of aspirin orally. However, immediate analgesic activity of the derivatives was lower than that of aspirin and persistent activity was similar as that of aspirin. And the stomach mucous membrane morphology change of the derivatives was much milder than that of aspirin. The salicylic acid grafted chitosan derivatives showed synergistic and complementary effect on the anti-inflammatory and analgesic activities and so on.

Development of molecular probes for second-site screening and design of protein tyrosine phosphatase inhibitors

We report on the design, synthesis, and evaluation of a series of furanyl-salicyl-nitroxide derivatives as effective chemical probes for second-site screening against phosphotyrosine phosphatases (PTPs) using NMR-based techniques. The compounds have been tested against a panel of PTPs to assess their ability to inhibit a broad spectrum of these phosphatases. The utility of the derived compounds is illustrated with the phosphatase YopH, a bacterial toxin from Yersinia pestis. Novel chemical fragments were identified during an NMR-based screen for compounds that are capable of binding on the surface of YopH in regions adjacent the catalytic site in the presence of the spin-labeled compounds. Our data demonstrate the value of the derived chemical probes for NMR-based second-site screening in PTPs.

Queen sex pheromone of the slave-making ant, Polyergus breviceps

Workers of the slave-making ant, Polyergus breviceps, raid nests of Formica ants and return with Formica pupae that mature into worker ants in the slave-makers' colony. These Formica workers then tend the Polyergus brood, workers, and reproductives. During raids in the mating season, winged virgin Polyergus queens accompany the workers in the raiding columns. During the raid, the virgin queens release a pheromone that attracts males that quickly mate with the queens. We report the identification, synthesis, and bioassay of the sex attractant pheromone of the queens as an approximately 1:6 ratio of (R)-3-ethyl-4-methylpentan-1-ol and methyl 6-methylsalicylate. The ants produce exclusively the (R)-enantiomer of the alcohol, and the (S)-enantiomer has no biological activity, neither inhibiting nor increasing attraction to blends of methyl 6-methylsalicylate with the (R)-enantiomer.

2-(4-Chlorobenzyl)-3-hydroxy-7,8,9,10-tetrahydrobenzo[H]quinoline-4-carboxylic Acid (PSI-697): Identification of a Clinical Candidate from the Quinoline Salicylic Acid Series of P-Selectin Antagonists

P-selectin-PSGL-1 interaction causes rolling of leukocytes on the endothelial cell surface, which subsequently leads to firm adherence and leukocyte transmigration through the vessel wall into the surrounding tissues. P-selectin is upregulated on the surface of both platelets and endothelium in a variety of atherosclerosis-associated conditions. Consequently, inhibition of this interaction by means of a small molecule P-selectin antagonist is an attractive strategy for the treatment of atherosclerosis. High-throughput screening and subsequent analoging had led to the identification of compound 1 as the lead candidate. Herein, we report the continuation of this work and the discovery of a second-generation series, the tetrahydrobenzoquinoline salicylic acids. These compounds have improved pharmacokinetic properties, and a number of them have shown oral efficacy in mouse and rat models of atherogenesis and vascular injury. The lead 31 (PSI-697), is currently in clinical development for the treatment of atherothrombotic vascular events.

Synthesis and Biological Evaluation of Quinoline Salicylic Acids As P-Selectin Antagonists

Leukocyte recruitment of sites of inflammation and tissue injury involves leukocyte rolling along the endothelial wall, followed by firm adherence of the leukocyte, and finally transmigration of the leukocyte across cell junctions into the underlying tissue. The initial rolling step is mediated by the interaction of leukocyte glycoproteins containing active moieties such as sialyl Lewisx (sLex) with P-selectin expressed on endothelial cells. Consequently, inhibition of this interaction by means of a small molecule P-selectin antagonist is an attractive strategy for the treatment of inflammatory diseases such as arthritis. High-throughput screening of the Wyeth chemical library identified the quinoline salicylic acid class of compounds (1) as antagonists of P-selectin, with potency in in vitro and cell-based assays far superior to that of sLex. Through iterative medicinal chemistry, we identified analogues with improved P-selectin activity, decreased inhibition of dihydrooratate dehydrogenase, and acceptable CYP profiles. Lead compound 36 was efficacious in the rat AIA model of rheumatoid arthritis.

Novel inhibitors of the trypanosome alternative oxidase inhibit Trypanosoma brucei brucei growth and respiration

African trypanosomiasis is a deadly disease for which few chemotherapeutic options are available. The causative agents, Trypanosoma brucei rhodesiense and T. b. gambiense, utilize a non-cytochrome, alternative oxidase (AOX) for their cellular respiration. The absence of this enzyme in mammalian cells makes it a logical target for therapeutic agents. We designed three novel compounds, ACB41, ACD15, and ACD16, and investigated their effects on trypanosome alternative oxidase (TAO) enzymatic activity, parasite respiration, and parasite growth in vitro. All three compounds contain a 2-hydroxybenzoic acid moiety, analogous to that present in SHAM, and a prenyl side chain similar to that found in ubiquinol. ACD15 and ACD16 are further differentiated by the presence of a solubility-enhancing carbohydrate moiety. Kinetic studies with purified TAO show that all three compounds competitively inhibit TAO, and two compounds, ACB41 and ACD15, have inhibition constants five- and three-fold more potent than SHAM, respectively. All three compounds inhibited the respiration and growth of continuously cultured T. b. brucei bloodstream cells in a dose-dependent manner. None of the compounds interfered with respiration of rat liver mitochondria, nor did they inhibit the growth of a continuously cultured mammalian cell line. Collectively, the results suggest we have identified a new class of compounds that are inhibitors of TAO, have trypanocidal properties in vitro, and warrant further investigation in vivo.

Novel chemically synthesized salicylate derivative as an effective elicitor for inducing the biosynthesis of plant secondary metabolites

Trifluoroethyl salicylate (TFESA), a novel salicylate derivative, was chemically synthesized and evaluated by bioassay as a potential elicitor for inducing the biosynthesis of plant secondary metabolites. A cell line of Taxus chinensis, which stably produced a high level of bioactive taxuyunnanine C (Tc), was taken as a model plant cell system. The application of TFESA to the cell cultures could significantly induce Tc biosynthesis, although the cell growth was slightly inhibited. More interestingly, Tc production was enhanced more in the presence of TFESA compared with a structure-similar well-known elicitor, salicylic acid (SA). For example, addition of 100 microM TFESA on day 7 led to a high Tc content of 21.9 +/- 0.1 mg g(-1) (at day 21), whereas the Tc content was 14.0 +/- 0.2 and 16.7 +/- 0.3 mg g(-1) for the control and that with addition of 100 microM SA, respectively. The results indicate that the newly synthesized TFESA can act as a powerful elicitor for secondary metabolism induction in plant cell cultures.

[Structure-activity relationships of salicylic acid and its analogs in the inhibitory action on beta-lactamase]

AIM

Nineteen compounds related to salicylic acid were evaluated for their in vitro activity of inhibiting beta-lactamase isolated from a resistant strain of Pseudomonas aeruginosa, and their structure-activity relationships were examined.

METHODS

Nitrocefin method was used.

RESULTS

The 50% inhibitory concentration (IC50) of salicylic acid inhibiting beta-lactamase was 22 mmol x L(-1); four analogs had IC50 lower than that of salicylic acid; fifteen analogs had IC50 higher than that of salicylic acid.

CONCLUSION

Examination of the structure-activity relationships of the compounds revealed that carboxyl group and adjoining hydroxyl group were active group, and replacement of adjoining hydroxyl by carboxyl increased activity nearly 4-fold. Moreover, addition of a sulfonic group at C-5 and nitro group at C-3, 5 of benzenoic ring of salicylic acid resulted in a 2-fold to 3-fold increase in activity, addition of a amino group at C-5 of benzenoic ring of salicylic acid decreased activity, add addition of -Cl or -F at C-2,4 position of benzenoic ring of benzoic acid did not show activity.

Directed Ortho-Metalation of Unprotected Benzoic Acids. Methodology and Regioselective Synthesis of Useful Contiguously 3- and 6-Substituted 2-Methoxybenzoic Acid Building Blocks

[reaction: see text] By treatment with s-BuLi/TMEDA at -78 degrees C, unprotected 2-methoxybenzoic acid is deprotonated exclusively in the position ortho to the carboxylate. A reversal of regioselectivity is observed when the acid is treated with n-BuLi/t-BuOK. These results are of general utility for the one-pot preparation of a variety of very simple 3- and 6-substituted 2-methoxybenzoic acids that are not easily accessible by conventional means. The potential usefulness of the method is demonstrated by the expedient synthesis of lunularic acid.

Synthesis and anti-inflammatory testing of some new compounds incorporating 5-aminosalicylic acid (5-ASA) as potential prodrugs

This work includes the synthesis of 15 final compounds (6a-h and 7b-h) as prodrugs of 5-ASA in the form of the acid itself, esters and amides linked by an amide linkage through a spacer to the endocyclic ring N of nicotinamide. Also, 15 new intermediate compounds were prepared. The target compounds (6b, 6f, 7b, and 7e-h) revealed potent analgesic and anti-inflammatory activities in comparison to sulfasalazine and 5-ASA. In addition, ulcerogenicity, LD50, in vivo and in vitro metabolism of compound 7f were determined.

Synthesis of Photoactivatable Acyclic Analogues of the Lobatamides

[structure: see text] The lobatamides and related salicylate enamide natural products are potent mammalian V-ATPase inhibitors. To probe details of binding of the lobatamides to mammalian V-ATPase, three photoactivatable analogues bearing benzophenone photoaffinity labels have been prepared. The analogues were designed on the basis of a simplified acyclic analogue 2. Late-stage installation of the enamide side chain and tandem deallylation/amidation were employed in synthetic routes to these derivatives. Simplified analogue 2 showed strong inhibition against bovine clathrin-coated vesicle V-ATPase (10 nM). Analogues 3-5 were also evaluated for inhibition of bovine V-ATPase in order to select a suitable candidate for future photoaffinity labeling studies.

catena-Poly[[bis(1H-benzimidazole-kappaN3)(salicylato-kappaO)copper(II)]-mu-salicylato-O,O':O'']

The title compound, [Cu(C7H5O3)2(C7H6N2)2]n, is a one-dimensional polymeric complex bridged by salicylate anions. The Cu(II) atom is surrounded by three salicylate and two benzimidazole ligands, with a tetragonally elongated octahedral coordination geometry. The Cu-O bond distances in the axial directions are 2.6092 (16) and 2.6834 (17) A. pi-pi stacking interactions exist between the benzimidazole rings of neighboring polymeric complex chains.

Crystal structure and characterization of the dinuclear Cd(II) complex [Cd(H2O)2(o-HOC6H4COO)2]2

The structure of a new binuclear cadmium (II) complex, [Cd(H2O)2(Sal)2]2 (Sal= salicylate), has been determined by X-ray crystallography. It was also characterized by elemental analysis, its IR spectrum and thermogravimetric-differential scanning calorimetry (TG-DSC). It crystallizes in the monoclinic system, space group P2(1)/c, with lattice parameters a = 15.742(3) A, b = 12.451(3) A, c = 7.7225(15) A, beta = 96.07(3)degrees and Z = 4. Two cadmium (II) ions are bridged by two mu(2)-carboxy oxygen atoms. Each cadmium atom lies in a distorted capped octahedron coordination geometry. The thermal gravimetry (TG) data indicate that there are four discrete decomposition steps with two endothermic peaks and one exothermic peak. The final thermal decomposition product is CdO.

Potential antipsoriatic avarol derivatives as antioxidants and inhibitors of PGE(2) generation and proliferation in the HaCaT cell line

The synthesis and structure-activity relationships for a series of 14 new avarol derivatives as antioxidants and inhibitors of cell proliferation and PGE(2) generation in human keratinocytes are described. Compound 6 (thiosalicylic derivative) was the most potent inhibitor of superoxide generation in human neutrophils and also potently inhibited PGE(2) generation in the human keratinocyte HaCaT cell line. Compound 7(3'-methylaminoavarone) presented the best antiproliferative profile, by the inhibition of (3)H-thymidine incorporation in HaCaT cells, with potency similar to the reference compound anthralin. None of the avarol derivatives showed any sign of cytotoxicity measured as LDH release in treated keratinocytes. The potency and pharmacological profile of derivatives are also discussed.

[Influence of 2-aryl-3-halogen/3-hydroxy-1,4-naphthoquinones with salicylic and cinnamic acid partial structures on the arachidonic acid cascade]

Searching for more potent 5-lipoxygenase (LO) inhibitors one tert-butyl group of the selective 5-LO-inhibitor 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-hydroxy-1,4-naphthoquinone (1) was substituted by polar functions (-CHO, -COOH, -CH=CH-COOR, -CH2-CH2-COOR). At the same time the 5-LO selectivity of the new compounds within the arachidonic acid cascade was investigated. For this 12-LO- and COX-1-assays with activated human platelets were used. Screening the test compounds new selective 5-LO-inhibitors (4, 9 and 16) and a COX-1-inhibitor (10) as well as dual 5-LO/COX-1- (23) and 12-LO/COX-1- (12) inhibiting compounds were found. Obviously in this class of compounds 5-LO and 12-LO inhibition are mutually excluded for a structural reason. In addition to the well known 3-chloro- (19) and 3-bromo- (20) analogues of 1 the 3-fluoro- (22), 3-iodo- (23) and the 3-carbonitrile- (24) derivatives were synthesized. All 3-halogen compounds, except 23 and the nitrile, are potent non selective inhibitors of all three enzymes. Causative for this unselectivity is the inhibition of the arachidonic acid release by inhibition of the cytosolic phospholipase A2 (cPLA2) with the exception of 24.

Divergent and Stereocontrolled Synthesis of the Enamide Side Chains of Oximidines I/II/III, Salicylihalamides A/B, Lobatamides A/D, and CJ-12,950

[reaction: see text] A unified strategy for the divergent and stereocontrolled introduction of the (E)- and (Z)-enamide side-chains of oximidines I, II, and III, salicylihalamides A and B, lobatamides A and D, and CJ-12,950 is detailed. The synthesis relied on the copper-promoted C-N coupling of (E)- and (Z)-vinyl iodides with a protected maleimide hemiaminal followed by deprotection and reaction of the resulting (E)- or (Z)-enelactam hemiaminals with O-methylhydroxylamine or propylidenetriphenylphosphorane.

Selective protein tyrosine phosphatase 1B inhibitors: targeting the second phosphotyrosine binding site with non-carboxylic acid-containing ligands

Protein tyrosine phosphatase (PTPase) 1B (PTP1B) has been implicated as a key negative regulator of both insulin and leptin signaling cascades. We identified several salicylic acid-based ligands for the second phosphotyrosine binding site of PTP1B using a NMR-based screening. Structure-based linking with a catalytic site-directed oxalylarylaminobenzoic acid-based pharmacophore led to the identification of a novel series of potent PTP1B inhibitors exhibiting 6-fold selectivity over the highly homologous T-cell PTPase (TCPTP) and high selectivity over other phosphatases.

Lobatamide C: total synthesis, stereochemical assignment, preparation of simplified analogues, and V-ATPase inhibition studies

The total synthesis and stereochemical assignment of the potent antitumor macrolide lobatamide C, as well as synthesis of simplified lobatamide analogues, is reported. Cu(I)-mediated enamide formation methodology has been developed to prepare the highly unsaturated enamide side chain of the natural product and analogues. A key fragment coupling employs base-mediated esterification of a beta-hydroxy acid and a salicylate cyanomethyl ester. Three additional stereoisomers of lobatamide C have been prepared using related synthetic routes. The stereochemistry at C8, C11, and C15 of lobatamide C was assigned by comparison of stereoisomers and X-ray analysis of a crystalline derivative. Synthetic lobatamide C, stereoisomers, and simplified analogues have been evaluated for inhibition of bovine chromaffin granule membrane V-ATPase. The salicylate phenol, enamide NH, and ortho-substitution of the salicylate ester have been shown to be important for V-ATPase inhibitory activity.

DISAL glycosyl donors for the synthesis of a linear hexasaccharide under mild conditions

[reaction: see text] The new class of glycosyl donors with a methyl 3,5-dinitrosalicylate (DISAL) anomeric leaving group has proved efficient for glycosylation under strictly neutral, mildly basic, or mildly acidic conditions. Here, we report the synthesis of novel DISAL disaccharide glycosyl donors prepared by easy nucleophilic aromatic substitution. These DISAL donors proved efficient in the synthesis of a starch-related hexasaccharide under very mild conditions. Glycosylations proceeded with alpha-selectivity and were compatible with Trt protecting groups.