Orally active factor Xa inhibitor: synthesis and biological activity of masked amidines as prodrugs of novel 1,4-diazepane derivatives

Factor Xa (fXa) is a serine protease, which plays a pivotal role in the coagulation cascade. To improve the oral anticoagulant activity of fXa inhibitors containing a 1,4-diazepane moiety as the P4 part, a prodrug strategy was examined. Among the compounds evaluated in this study, amidoxime prodrugs bearing an ester moiety, such as compounds 21 and 30, showed effective oral anticoagulant activity in mice.     

Design,synthesis and biological evaluation of novel acetamide-substituted doravirine and its prodrugs as potent HIV-1 NNRTIs

A novel series of acetamide-substituted derivatives and two prodrugs of doravirine were designed and synthesized as potent HIV-1 NNRTIs by employing the structure-based drug design strategy. In MT-4 cell-based assays using the MTT method, it was found that most of the new compounds exhibited moderate to excellent inhibitory potency against the wild-type (WT) HIV-1 strain with a minimum EC₅₀ value of 54.8?nM. Among them, the two most potent compounds 8i (EC₅₀?=?59.5?nM) and 8k (EC₅₀?=?54.8?nM) displayed robust activity against WT HIV-1 with double-digit nanomolar EC₅₀ values, being superior to lamivudine (3TC, EC₅₀?=?12.8?μM) and comparable to doravirine (EC₅₀?=?13?nM). Besides, 8i and 8k shown moderate activity against the double RT mutant (K103N?+?Y181C) HIV-1 RES056 strain. The HIV-1 RT inhibition assay further validated the binding target. Molecular simulation of the representative compounds was employed to provide insight on their structure-activity relationships (SARs) and direct future design efforts. Finally, the aqueous solubility and chemical stability of the prodrugs 9 and 10 were investigated in detail.     

New phosphoramidates as protecting groups in ribooligonucleotides synthesis.

N, N-Dimethyl-p-phenylenediamine, glycine amide and p-methylthioaniline were condensed with uridine 5'-phosphate and the phosphoramidates obtained were tested for their stability in anhydrous pyridine, 50% aqueous pyridine or 80% acetic acid. The p-methylthioanilidate (IIc) was oxidized to give p-methylsulfoxylanilidate of uridine 5'-phosphate (IId) which was found to be 5 times more stable than the p-methylthio compound. The p-methylsulfoxylanilidate of 2'-O-benzoyluridine 3'-phosphate was condensed with the mononucleotide to yield the dinucleotide, MMTrU(OBz)-p-U(OBz)-p in 28% yield.     

Selective bone targeting 5-fluorouracil prodrugs: synthesis and preliminary biological evaluation

Bone tumor is a notoriously difficult disease to manage, requiring frequent and heavy doses of systemically administered chemotherapy. Targeting anticancer drug to the bone after systemic administration may provide both greater efficacy of treatment and less frequent administration. In this paper, a series of bone targeting Asp oligopeptides 5-fluorouracil conjugates have been synthesized in a convergent approach and well characterized by NMR and MS techniques. Their hydroxyapatite (HAP) affinity, drug release and cytotoxicity characteristics were evaluated in in vitro conditions. All the prodrugs were water soluble and exhibited high affinity to HAP .The efficient release of the active drug moiety occurring by the cleavage of different linkage in physiological conditions significantly reduced the number of viable human cancer cells. From in vivo distribution, we get these compounds with high bone-selectivity and long halflife. These results provided an effective entry to the development of new bone targeting chemotherapeutic drugs.     

Design, synthesis, and biological activity of folate receptor-targeted prodrugs of thiolate histone deacetylase inhibitors

Aiming to develop selective anticancer drugs, we designed and synthesized three disulfides bearing a folic acid moiety as candidate folate receptor (FR)-targeted prodrugs of thiolate histone deacetylase inhibitors. Among them, compound 1 displayed growth-inhibitory activity toward folate receptor-positive MCF-7 breast cancer cells. The activity of 1 was significantly reduced by free folic acid, suggesting that cellular uptake of 1 is mediated by FR.     

Design,synthesis, and biological evaluation of pyrrolobenzodiazepine-containing hypoxia-activated prodrugs

The ability of various pyrrolobenzodiazepine(PBD)-containing cytotoxic compounds to function as hypoxia-activated prodrugs was assessed. These molecules incorporated a 1-methyl-2-nitro-1H-imidazole hypoxia-activated trigger (present in the clinically evaluated compound TH-302) in a manner that masked a reactive imine moiety required for cytotoxic activity. Incubation of the prodrugs with cytochrome P450-reductase under normoxic and hypoxic conditions revealed that some, but not all, were efficient substrates for the enzyme. In these experiments, prodrugs derived from PBD-monomers underwent rapid conversion to the parent cytotoxic compounds under low-oxygen conditions while related PBD-dimers did not. The ability of a given prodrug to function as an efficient cytochrome P450-reductase substrate correlated with the ratio of cytotoxic potencies measured for the compound against NCI460 cells under normoxic and hypoxic conditions.     

Synthesis and biological evaluation of LNA phosphoramidates

The synthesis of LNA phosphoramidates is presented. The LNA phosphoramidates were evaluated for their ability to inhibit cell proliferation of the human prostate cancer cell line 15PC3. A number of the LNA phosphoramidates showed cell proliferation inhibition determined by the MTS assay.     

Expedient synthesis and biological evaluation of alkenyl acyclic nucleoside phosphonate prodrugs

The importance of phosphonoamidate prodrugs (ProTides) of acyclic nucleoside phosphonate (ANPs) is highlighted by the approval of Tenofovir Alafenamide Fumarate for the treatment of HIV and HBV infections. In the present paper we are reporting an expedient, one-pot, two-steps synthesis of allyl phosphonoamidates and diamidates that offers a time saving strategy when compared to literature methods. The use of these substrates in the cross metathesis reactions with alkenyl functionalised thymine and uracil nucleobases is reported. ANPs prodrugs synthesized via this methodology were evaluated for their antiviral activities against DNA and RNA viruses. It is anticipated that the use of 5,6,7,8-tetrahydro-1-napthyl as aryloxy moiety is capable to confer antiviral activity among a series of otherwise inactive uracil ProTides.     

Stereochemical influence on lipase-mediated hydrolysis and biological activity of stampidine and other stavudine phosphoramidates

Stampidine and other halogen substituted stavudine phosphoramidates can be activated by lipase-mediated hydrolysis. The target site for the lipase appears to be the methyl ester group of the L-alanine side chain. Accordingly, the D-amino acid substituted isomers {Rp or Sp}are resistant to lipase-mediated hydrolysis and exhibit substantially less anti-HIV activity. Molecular modeling results indicate that the L-amino acid configured isomers {Rp or Sp} are preferred in the lipase binding pocket.     

Design and synthesis of anticonvulsive agents as gamma-vinyl GABA-based potential dual acting prodrugs and their biological activities

For the development of new anticonvulsive agents, gamma-vinyl GABA (vigabatrin) and GABA mimetics derivatives were covalently coupled as potential dual acting prodrugs and evaluated for their anticonvulsive activities. Among the prepared compounds, 11 showed the most potent anticonvulsive activity, a shorter onset time and a broader spectrum compared to vigabatrin.     

Design and synthesis of vidarabine prodrugs as antiviral agents

5′-O-d- and l-amino acid derivatives and 5′-O-(d- and l-amino acid methyl ester phosphoramidate) derivatives of vidarabine (ara-A) were synthesized as vidarabine prodrugs. Some compounds were equi- or more potent in vitro than vidarabine against two pox viruses and their uptake by cultured cells was improved compared to the parent drug.     

Beta-cell tropin: synthesis and biological activity

The structure of beta-cell tropin, an insulin secretagogue released by the neuro-intermediate lobe of the obese (ob/ob) mouse, has recently been determined as the 22-39 moiety of ACTH. A method for the preparation of this octadecapeptide using mild solid-phase procedures followed by preparative high pressure liquid chromatography is described. The molecular weight of the synthetic peptide has been confirmed by Fast Atom Bombardment mass spectrometry. Synthetic beta-cell tropin is indistinguishable in its chromatographic, antigenic and biological properties from natural beta-cell tropin.     

New analogues of AHMA as potential antitumor agents: synthesis and biological activity

A series of new analogues of 3-(9-acridinylamino)-5-hydroxymethylaniline (AHMA, 1) and AHMA-ethylcarbamate (2) were synthesized by introducing an O-alkylcarboxylic acid esters to the CH(2)OH function, displacing the CH(2)OH function with a dimethylaminocarboxamido group or with a methyl function introduced at the meta-, para- or ortho-position to the NH(2) group to form 5-(9-acridinylamino)-m-toluidines (AMTs), 5-(9-acridinylamino)-p-toluidines (APTs) or 5-(9-acridinylamino)-o-toluidines (AOTs), respectively. The inhibitions of a variety of human tumor cell growth, interactions with DNA as well as inhibitory effect against topoisomerase II (Topo II) of these new agents were studied. Among AMT, APT and AOT derivatives with dimethylaminoethylcarboxamido and Me at C4 and C5 of acridine moiety (i.e., 21c, 23c and 26c) were more cytotoxic than AHMA (1) and AHMA-ethylcarbamate (2), depending upon the tumor cell line tested. Detailed structure-activity relationships of the new analogues were studied.     

Synthesis and biological activity of water-soluble maleimide derivatives of the anticancer drug carboplatin designed as albumin-binding prodrugs

Four platinum (II) complexes (13-16) were synthesized by reacting either [Pt trans-DACH](NO(3))(2) with a 6-maleimidocaproic acid, a 15-maleimido-4,7,10,13-tetroxapentadecanoic acid, and a 6-maleimido-4-oxacaproic ester derivative of cyclobutane-1,1-dicarboxylic acid (CDBA) or [Pt(NH(3))(2)](NO(3))(2) with a 6-maleimido-4-oxacaproic ester derivative of CBDA. Both complexes containing the 6-maleimido-4-oxacaproic ester (15, 16) showed good water solubility (>/=8 mg/mL) and CE experiments revealed rapid binding to human serum albumin and the formation of biadducts with dGMP and dAMP. In the MaTu xenograft model in nude mice, both complexes showed an improved antitumor effect at their maximum tolerated dose (2 x 50 mg/kg carboplatin equivalents) compared to therapy with carboplatin at equimolar dose or at its optimal dose (2 x 75 mg/kg).     

Phosphonooxymethyl prodrugs of the broad spectrum antifungal azole, ravuconazole: synthesis and biological properties

Synthesis of phosphonooxymethyl derivatives of ravuconazole, 2 (BMS-379224) and 3 (BMS-315801) and their biological evaluation as potential water-soluble prodrugs of ravuconazole are described. The phosphonooxymethyl ether analogue 2 (BMS-379224) and N-phosphonooxymethyl triazolium salt 3 (BMS-315801) were both prepared from ravuconazole (1) and bis-tert-butyl chloromethylphosphate, but under two different conditions. Both derivatives were highly soluble in water and converted to the parent in alkaline phosphatase, and also in vivo (rat). However, BMS-315801 was found to be less stable than BMS-379224 in water at neutral pH. BMS-379224 (2) has proved to be one of the most promising prodrugs of ravuconazole that we tested, and it is currently in clinical evaluation as an intravenous formulation of the broad spectrum antifungal azole, ravuconazole.     

Synthesis and biological evaluation of L-valine-amidoximeesters as double prodrugs of amidines

In general, drugs containing amidines suffer from poor oral bioavailability and are often converted into amidoxime prodrugs to overcome low uptake from the gastrointestinal tract. The esterification of amidoximes with amino acids represents a newly developed double prodrug principle creating derivatives of amidines with both improved oral availability and water solubility. N-valoxybenzamidine (1) is a model compound for this principle, which has been transferred to the antiprotozoic drug pentamidine (8). Prodrug activation depends on esterases and mARC and is thus independent from activation by P450 enzymes. Therefore, drug-drug interactions or side effects will be minimized. The synthesis of these two compounds was established, and their biotransformation was studied in vitro and in vivo. Bioactivation of N-valoxybenzamidine (1) and N,N'-bis(valoxy)pentamidine (7) via hydrolysis and reduction has been demonstrated in vitro with porcine and human subcellular enzyme preparations and the mitochondrial Amidoxime Reducing Component (mARC). Moreover, activation of N-valoxybenzamidine (1) by porcine hepatocytes was studied. In vivo, the bioavailability in rats after oral application of N-valoxybenzamidine (1) was about 88%. Similarly, N,N'-bis(valoxy)pentamidine (7) showed oral bioavailability. Analysis of tissue samples revealed high concentrations of pentamidine (8) in liver and kidney.     

Design,synthesis, and biological evaluation of a series of beta-lactam-based prodrugs

By use of pro-dual-drug concept the synthesis of 6-beta-[(R)-2-(clavaminio-9-N-yl)-2-(4-hydroxyphenylacetamido)]penicillanic acid (10), 6-beta-[(R)-2-(amino)-2-(4-(clavulano-9-O-yl)phenylacetamido)]penicillanic acid (13), (Z)-4-[2-(amoxycillin-4-O-yl)ethylidene]-2-(clavulano-9-O-yl)-3-methoxy-Delta(alpha,beta)-butenolide (19), and 3-[(amoxicillin-4-O-yl)methyl]-7-(phenoxyacetamido)-(1-oxo)-3-cephem-4-carboxylic acid (23) was accomplished. Unlike penicillin G, ampicillin, or amoxicillin, these four heretofore undescribed compounds 10, 13, 19, and 23 showed notable activity against beta-lactamase (betaL) producing microorganisms, Staphylococcus aureus A9606, S. aureus A15091, S. aureus A20309, S. aureus 95, Escherichia coli A9675, E. coli A21223, E. coli 27C7, Pseudomonas aeruginosa 18S-H, and Klebsiella pneumoniae A20634 TEM. In comparison with amoxicillin (9), alpha-amino-substituted compound 10 and butenolide derivative 19 showed a broadened spectrum of antibacterial activity; yet they were found to be less active than 13 and 23. Like clavulanic acid (7) or cephalosporin-1-oxide (21), the newly synthesized compounds 10, 13, 15, 16, 19, or 23 functioned as potent inhibitors of various bacterial betaLs.     

Flurbiprofen derivatives in Alzheimer's disease: synthesis, pharmacokinetic and biological assessment of lipoamino acid prodrugs

Flurbiprofen (FLU) lipophilic prodrugs with lipoamino acids (LAA) 6a- e were synthesized for brain delivery. Chemical and plasmatic stability of prodrugs 6a- e as well as pharmacokinetic distribution studies for the prodrugs 6b and 6d were carried out. FLU prodrugs 6a- e were compared to the parent drug for their ability to inhibit binding of [F-18]FDDNP to in vitro formed beta-amyloid protein (Abeta fibrils). FLU-LAA conjugates showed a typical prodrug stability profile, being stable in PBS at pH 7.4 and releasing the active drug in plasma. Compound 6d yielded a slow accumulation of FLU in the brain. In the in vitro inhibition assay, all prodrugs except for the prodrug with the longest alkyl side chain ( 6e) were effective as inhibitors of [F-18]FDDNP binding to Abeta fibrils with EC50 values in the 10-300 nM range. The different brain accumulation kinetics shown by FLU and its LAA conjugate 6d suggested a possible slow-releasing activity of FLU by these prodrugs in the brain or a differential pharmacological effect deserving further, detailed studies on their biodistribution and pharmacological profile.     

Mannich bases of scutellarein as thrombin-inhibitors: Design,synthesis, biological activity and solubility

Two series of 8-aminomethylated derivatives were prepared by Mannich reaction of scutellarein (2) with appropriate aliphatic amines, alicyclic amines and formaldehyde. All the compounds were tested for their thrombin inhibition activity through the analyzation of prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen (FIB). The antioxidant activities of these target products were assessed by 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH) assay using 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay method and the solubility were assessed by ultraviolet (UV). The results showed that morpholinyl aminomethylene substituent derivative (3d) demonstrated stronger anticoagulant activity, better water solubility and good antioxidant activity compared with scutellarein (2), which warrants further development as a agent for ischemic cerebrovascular disease treatment.     

Synthesis and biological evaluation of aryl phosphoramidate prodrugs of fosfoxacin and its derivatives

Aryl phosphoramidate prodrugs of fosfoxacin derivatives 15a-b and 8a-b were synthesized and investigated for their ability to target bacteria. No growth inhibition was observed neither for Mycobacterium smegmatis nor for Escherichia coli on solid medium, demonstrating the absence of release of the active compounds in the bacterial cells. Investigation of the stability of the prodrugs and their multienzymatic cleavage in abiotic and biotic conditions showed that the use of aryl phosphoramidate prodrug approach to deliver non-nucleotides compounds is not obvious and might not be appropriate for an antimicrobial drug.