Synthesis of non-immunosuppressive cyclophilin-Binding cyclosporin A derivatives as potential anti-HIV-1 drugs

Original cyclosporin A (CsA) derivatives bearing various alkylthio side chains at the sarcosine residue 3 (R configuration) and for the most potent and selective compounds a 4'-hydroxyl group at the Me-Leucine residue 4 were prepared in one or two steps from commercially available CsA. The [2-(dimethyl or diethylamino)-ethylthio-Sar](3)-[(4'-OH)MeLeu](4)-CsA derivatives 3k and 3l displayed potent in vitro anti-HIV-1 (IC(50) approximately 46 nM) and low immunosuppressive activities (IC(50)>or=1500 nM).

Topical delivery of 5-fluorouracil (5-FU) by 3-alkylcarbonyloxymethyl-5-FU prodrugs

The 3-alkylcarbonyloxymethyl-5-fluorouracil (3-ACOM-5-FU) prodrugs have been characterized by their solubilities in isopropyl myristate (S(IPM)) and partition coefficients between IPM and pH 4.0 buffer (K(IPM:AQ)). Estimated S(AQ) values have been obtained from S(AQ) = S(IPM)/K(IPM:AQ.) The abilities of the prodrugs to deliver total 5-FU species from IPM suspensions through hairless mouse skin (J(i)) have been evaluated in diffusion cell experiments. All of the prodrugs were much more soluble in IPM than 5-FU, and the propionyloxymethyl (C2) member of the series was almost twice as soluble in pH 4.0 buffer. Except for the acetyloxymethyl (C1) member of the series, the 3-ACOM-5-FU prodrugs exhibited greater S(IPM) and S(AQ) values than the corresponding 1-alkylcarbonyloxymethyl (1-ACOM-5-FU) prodrugs. The 3-ACOM-5-FU prodrugs that exhibited greater S(IPM) and S(AQ) values than the 1-ACOM-5-FU prodrugs also exhibited greater J(i) values, except for the C2 member. The C2 member also gave the largest error in predicting J(i) using the transformed Potts-Guy equation. All of the 3-ACOM-5-FU prodrugs delivered more 5-FU as a percentage of J(i) than the 1-ACOM-5-FU prodrugs but were not more effective as a series at targeting dermal as opposed to transdermal delivery.

Search for new lead structures in the isoxazole heterocyclic system

Looking for active immunosuppressant, a series of substituted phenylamides of 5-aminomethinimino-3-methylisoxazole-4-carboxylic acid was obtained, which showed immunosuppressory activities in the in vitro and in vivo tests, comparable with that of cyclosporine A. Rentgenostructural studies of three most representative derivatives were performed and the molecular modelling of compounds, demonstrating most characteristic biological activities, was performed. In the next stage, quantum-chemical investigations were conducted in order to determine structure-activity relationships.

Optimization of 2-phenylaminoimidazo[4,5-h]isoquinolin-9-ones: orally active inhibitors of lck kinase

The tyrosine kinase p56lck (lck) is essential for T cell activation; thus, inhibitors of lck have potential utility as autoimmune agents. Our initial disclosure of a new class of lck inhibitors based on the phenylaminoimidazoisoquinolin-9-one showed reasonable cellular activity but did not work in vivo upon oral administration. Our current work highlights the further use of rational drug design and molecular modeling to produce a series of lck inhibitors that demonstrate cellular activity below 100 nM and are as efficacious as cyclosporin A in an in vivo mouse model of anti-CD3-induced IL-2 production.

Sanglifehrin-cyclophilin interaction: degradation work, synthetic macrocyclic analogues, X-ray crystal structure, and binding data

Sanglifehrin A (SFA) is a novel immunosuppressive natural product isolated from Streptomyces sp. A92-308110. SFA has a very strong affinity for cyclophilin A (IC(50) = 6.9 +/- 0.9 nM) but is structurally different from cyclosporin A (CsA) and exerts its immunosuppressive activity via a novel mechanism. SFA has a complex molecular structure consisting of a 22-membered macrocycle, bearing in position 23 a nine-carbon tether terminated by a highly substituted spirobicyclic moiety. Selective oxidative cleavage of the C(26)=C(27) exocyclic double bond affords the spirolactam containing fragment 1 and macrolide 2. The affinity of 2 for cyclophilin (IC(50) = 29 +/- 2.1 nM) is essentially identical to SFA, which indicates that the interaction between SFA and cyclophilin A is mediated exclusively by the macrocyclic portion of the molecule. This observation was confirmed by the X-ray crystal structure resolved at 2.1 A of cyclophilin A complexed to macrolide 16, a close analogue of 2. The X-ray crystal structure showed that macrolide 16 binds to the same deep hydrophobic pocket of cyclophilin A as CsA. Additional valuable details of the structure-activity relationship were obtained by two different chemical approaches: (1) degradation work on macrolide 2 or (2) synthesis of a library of macrolide analogues using the ring-closing metathesis reaction as the key step. Altogether, it appears that the complex macrocyclic fragment of SFA is a highly optimized combination of multiple functionalities including an (E,E)-diene, a short polypropionate fragment, and an unusual tripeptide unit, which together provide an extremely strong affinity for cyclophilin A.

Synthesis and activity of substituted 2-phenylquinolin-4-amines, antagonists of immunostimulatory CpG-oligodeoxynucleotides

Fifty-seven 2-phenylquinolines substituted at the phenyl group and C4 of the quinoline were synthesized and analyzed for inhibition of the immunostimulatory effect of oligodeoxynucleotides with a CpG-motif. The Fujita-Ban variant of the classical Free-Wilson analysis gave a highly significant correlation for a series of 48 relatively small molecules demonstrating that (i) the partial contributions of substituents to biological activity (EC(50)) are additive and (ii) assuming similar bioavailability for all quinolines studied, the larger molecules cannot be accommodated within a still unknown biological receptor. The results suggest interaction of a basic antagonist molecule with weakly acidic groups in the antagonist-receptor complex. N-[2-(Dimethylamino)ethyl]-2-[4-(4-methylpiperazino)phenyl]quinolin-4-amine (50) is the most effective antagonist found in this study (EC(50) = 0.76 nM).

Novel amide-based inhibitors of inosine 5'-monophosphate dehydrogenase

A series of novel amide-based small molecule inhibitors of inosine monophosphate dehydrogenase (IMPDH) was explored. The synthesis and the structure-activity relationships (SARs) derived from in vitro studies are described.

Synthesis and immunosuppressive activity of novel succinylacetone analogues

This study describes the synthesis of novel enol esters (3) and triketones (4) as analogues of succinylacetone (SA) (Ed- this abbreviation is introduced here based on your use of it in the body of the paper) and the evaluation on the mouse allogeneic mixed lymphocyte reaction (MLR) and the murine model of antigen-induced paw edema formation for immunosuppressive activity. Enol esters (3a-f) were about 2-4 fold more potent than SA in in vitro activity.

Synthesis and biological evaluation of novel cyclosporin a analogues: potential soft drugs for the treatment of autoimmune diseases

Cyclosporin A is effective in the treatment of asthma patients, but its chronic use is limited by toxicity. Novel cyclosporin A analogues were synthesized utilizing the olefin metathesis reaction and evaluated in a calcineurin A inhibition assay. The novel analogues demonstrated activity comparable to activity of the parent molecule and are potential soft drugs.

Rational design and development of RDP58

We used a novel rational design approach in the development of novel immunomodulatory peptides, in particular RDP58, with at least two primary biological activities, inhibition of TNF production and upregulation of heme oxygenase-1 (HO-1) activity. The design strategy used a variety of topological and shape descriptors in combination with an analysis of molecular dynamics trajectories to identify potential drug candidates. The process was initiated using a panel of 19 lead molecules derived from a functionally-important region of HLA I, on the premise that the peptides might modulate immune responses by blocking HLA/T lymphocyte interactions. Each of these 19 peptides was tested in vivo for potential cardiac allograft protection in a mouse model. Outcome of graft survival was the primary data available to describe nine of the peptides as active and ten as inactive. A virtual combinatorial library of 279,936 peptides was then generated, based on physical properties associated with efficacy in the original learning set of 19 peptides--in particular, the distribution of lipophilic residues. The library was screened using descriptors that fell into 2 categories: static (physico-chemical) and dynamic (conformational). The screenings identified 5 peptides with theoretic potential efficacy. These were synthesized and tested for activity in vitro and in vivo. Besides prolonging graft survival in rodents, RDP58 was found to inhibit TNF and increase HO-1 activity; these biological activities were tested exhaustively in various in vivo disease models. RDP58 demonstrated convincing potential to alleviate disease symptoms in many of the experimental diseases.

Manufacture and quality control of CAMPATH-1 antibodies for clinical trials

BACKGROUND

CAMPATH-1 Abs have been used for T-cell depletion in stem-cell transplantation since the early 1980s. During that time there has been substantial progress in manufacturing techniques and quality control procedures. This article summarizes the methods used to produce the Abs for clinical use and describes results of quality control tests on representative batches.

METHODS

Rat hybridoma and recombinant CHO cells were cultured in hollow-fiber fermentors. Antibodies were purified from the culture supernatant by fractionation with ammonium sulphate, or by column chromatography. Additional steps were added to assure the removal of DNA and viruses. A range of analytical methods was used to characterize the antibodies. Samples were stored frozen at -70 degrees C and re-analyzed many years later to assess the long-term stability.

RESULTS

Hollow-fiber fermentors provided a simple and reliable means for antibody production, with yields between 3-10 mg/h and a convenient concentration for further processing (0.6-2.0 mg/mL). All of the CAMPATH-1 Abs (rat IgM, rat IgG2b and human IgG1) could be purified by affinity chromatography on Protein A, but the low pH required for elution caused unacceptable aggregation of the IgM. CAMPATH-1H contained approx. 20% dimeric IgG, which could be removed by size exclusion chromatography. Antibodies were stable for at least 6 years at -70 degrees C, but there was unacceptable aggregation of CAMPATH-1M in one batch stored for 9 years.

DISCUSSION

Pilot-scale production of MAbs for clinical studies is feasible in a small academic center, but regulatory requirements now demand that great attention is paid to all aspects of manufacturing and quality assurance. Although the underlying principles of cell culture and protein chemistry remain the same, the level of documentation, validation and quality control has increased greatly over the last 20 years.

Inhibition of murine dendritic cell activation by synthetic phosphorothioate oligodeoxynucleotides

Depending on sequence and backbone structure, DNA can inhibit as well as stimulate immune responses. As previously shown, single-base phosphorothioate (Ps) oligodeoxynucleotides (ODN) can inhibit murine macrophage activation. To determine whether these compounds can also affect dendritic cells (DC), the effects of 30-mer Ps ODN (SdA, SdT, SdG, and SdC) on DC activation were assessed in an in vitro system. With DC preparations obtained from murine bone marrow cultured in granulocyte macrophage-colony stimulating factor, the Ps ODN blocked the production of interleukin-12 and nitric oxide induced by bacterial DNA, an immunostimulatory cytosine phosphate guanosine dinucleotide (CpG) ODN and lipopolysaccharide (LPS). Furthermore, these compounds inhibited up-regulation of costimulatory molecules CD40 and CD86 as well as major histocompatibility complex-II molecules, indicating an effect on DC maturation. Although the Ps ODN limited uptake of CpG ODN as assessed by flow cytometry, the Ps ODN did not affect LPS uptake, suggesting that these compounds inhibit DC responses by effects on downstream signaling pathways. Together, these observations extend the range of action of inhibitory ODN to DC and suggest a role of these compounds as immunomodulatory agents.

[Neoglycoconjugates based on dendrimeric poly(aminoamides)]

Neoglycoconjugates containing 4, 8, 16, 32, and 64 terminal residues of B-disaccharide (BDI) or N-acetylneuraminic acid (Neu5Ac) attached to poly(aminoamide)-type dendrimers (PAMAMs) were synthesized. The ability of BDI conjugates to bind natural xenoantibodies (anti-BDI antibodies) and the ability of Neu5Ac conjugates to inhibit the hemagglutinin-mediated adhesion of influenza virus were studied. The biological activity of PAMAM conjugates turned out to be higher than that of free carbohydrate ligands, but less than that of multivalent glycoconjugates based on other types of synthetic polymeric carriers. A conformational analysis of PAMAM matrices and resulting conjugates was performed to determine the statistical distances between carbohydrate ligands. The computations revealed the tendency of the PAMAM chains toward compaction and formation of dense globules. The process results in a decrease in the distances between the carbohydrate ligands in the conjugates and, hence, could affect the ability of glycoconjugates to efficiently bind the polyvalent carbohydrate-recognizing proteins. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2002, vol. 28, no. 6; see also http://www.maik.ru.

Design, synthesis and bioactivities of novel diarylthiophenes: inhibitors of tumor necrosis factor-alpha (TNF-alpha) production

The design, synthesis and SAR of novel diarylthiophene derivatives were performed. These compounds were designed by structural hybridization of TNF-alpha production inhibitors bearing 4-fluorophenyl and 4-pyridyl groups such as FR133605, FR167653 and SB210313, and 6-acetyl-3-ethoxycarbonyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine (1) found previously by us. As a result, several compounds were more potent in vitro than FR133605 against TNF-alpha production stimulated with lipopolysaccharide (LPS).

Marked prolongation of cardiac allograft survival by dendritic cells genetically engineered with NF-kappa B oligodeoxyribonucleotide decoys and adenoviral vectors encoding CTLA4-Ig

Bone marrow-derived dendritic cells (DCs) can be genetically engineered using adenoviral (Ad) vectors to express immunosuppressive molecules that promote T cell unresponsiveness. The success of these DCs for therapy of allograft rejection has been limited in part by the potential of the adenovirus to promote DC maturation and the inherent ability of the DC to undergo maturation following in vivo administration. DC maturation occurs via NF-kappaB-dependent mechanisms, which can be blocked by double-stranded "decoy" oligodeoxyribonucleotides (ODNs) containing binding sites for NF-kappaB. Herein, we describe the combined use of NF-kappaB ODNs and rAd vectors encoding CTLA4-Ig (Ad CTLA4-Ig) to generate stably immature murine myeloid DCs that secrete the potent costimulation blocking agent. These Ad CTLA4-Ig-transduced ODN DCs exhibit markedly impaired allostimulatory ability and promote apoptosis of activated T cells. Furthermore, administration of Ad CTLA4-Ig ODN-treated donor DCs (C57BL10; B10(H-2b)) before transplant significantly prolongs MHC-mismatched (C3HHeJ; C3H(H-2k)) vascularized heart allograft survival, with long-term (>100 days) donor-specific graft survival in 40% of recipients. The mechanism(s) responsible for DC tolerogenicity, which may involve activation-induced apoptosis of alloreactive T cells, do not lead to skewing of intragraft Th cytokine responses. Use of NF-kappaB antisense decoys in conjunction with rAd encoding a potent costimulation blocking agent offers promise for therapy of allograft rejection or autoimmune disease with minimization of systemic immunosuppression.

Search for new synthetic immunosuppressants II. Tetrazole analogues of hymenistatin I

Linear and cyclic hymenistatin I (HS I) analogues with dipeptide segments Ile2-Pro3 Pro3-Pro4 and Val6-Pro7 replaced by their tetrazole analogues Ile2-psi[CN4]-Ala3', Pro3-psi[CN4]-Ala4 and Val6-psi[CN4]-Ala7 were synthesized by the solid phase peptide synthesis method and cyclized with the TBTU and/or HATU reagent. The peptides were examined for their immunosuppressive activity in the lymphocyte proliferation test (LPT).

Design, synthesis and biological evaluation of a new bridged immunosuppressor

A bridged peptide with the sequence: H-Thr-Pro-Gln-Arg-Gly-Asp-Val-gamma-Abu-Asn-Asp-Gln-Glu-Glu-Thr-Thr-Gly-Val-Val-Ser-Thr-Pro-Leu-Ile-Arg-Asn-Gly-OH was designed to mimic the discontinuous epitope of the HLA-DQ molecule that might interact with CD4. The bridged peptide revealed distinct suppressory effect in the humoral immune response. This result supports our suggestion that the 164-172 region of the HLA-DQ molecule may enhance its interactions with coreceptors, possibly with CD4.

Synthetic studies toward SNF4435 C and SNF4435 D

[reaction: see text] A synthetic approach toward the immunosuppressants SNF3345 C and SNF4435 D featuring a tandem Stille coupling/electrocyclization cascade is described.

Total synthesis of (-)-stevastelin B

The total synthesis and an unambiguous structure confirmation of stevastelin B 1, a novel 15-membered cyclic depsipeptide, are described; the fatty acid moiety in 1, prepared stereoselectively from L-quebrachitol was converted into the amino carboxylic acid, whose macrolactamization by Shioiri's procedure effectively constructed the cyclic structure of 1.

Identification of a new class of inhibitors of the voltage-gated potassium channel, Kv1.3, with immunosuppressant properties

The voltage-gated potassium channel, K(v)1.3, is a novel target for development of immunosuppressants. Using a functional (86)Rb(+) efflux assay, a new class of high-affinity K(v)1.3 inhibitors has been identified. The initial active in this series, 4-phenyl-4-[3-(2-methoxyphenyl)-3-oxo-2-azaprop-1-yl]cyclohexanone (PAC), which is representative of a disubstituted cyclohexyl (DSC) template, displays a K(i) of ca. 300 nM and a Hill coefficient near 2 in the flux assay and in voltage clamp recordings of K(v)1.3 channels in human T-lymphocytes. PAC displays excellent specificity as it only blocks members of the K(v)1 family of potassium channels but does not affect many other types of ion channels, receptors, or enzyme systems. Block of K(v)1.3 by DSC analogues occurs with a well-defined structure-activity relationship. Substitution at the C-1 ketone of PAC generates trans (down) and cis (up) isomer pairs. Whereas many DSC derivatives do not display selectivity in their interaction with different K(v)1.x channels, trans DSC derivatives distinguish between K(v)1.x channels based on their rates of C-type inactivation. DSC analogues reversibly inhibit the Ca(2+)-dependent pathway of T cell activation in in vitro assays. Together, these data suggest that DSC derivatives represent a new class of immunosuppressant agents and that specific interactions of trans DSC analogues with channel conformations related to C-type inactivation may permit development of selective K(v)1.3 channel inhibitors useful for the safe treatment of autoimmune diseases.

Synthesis of D-erythro-dihydrosphingosine and D-xylo-phytosphingosine from a serine-derived 1,5-dioxaspiro[3.2]hexane template

[reaction: see text] A serine-derived 1,5-dioxaspiro[3.2]hexane template is shown to be a useful precursor for both aminodiol and aminotriol sphingoid bases by its conversion to D-erythro-dihydrosphingosine and D-xylo-phytoshingosine.

[Synthesis and study of B-nor-8-isoanalogs of steroid estrogens]

The study of the binding of estradiol B-nor-8-isonalogues to estrogen receptors from the rat uterus helped create the proposed model of the corresponding ligand-receptor complexes. The use of this model ensured the choice of such micromodifications in this steroid group that sharply decreased their hormonal activity. By the example of 16,16-dimethyl-D-homo-B-nor-8-isoestrone, we demonstrated the possibility of the synthesis of the estrogen analogues devoid of uterotropic activity but retaining immunosuppressive activity.

The immunosuppressive activity of peptide fragments of vaccinia virus C10L protein and a hypothesis on the role of this protein in the viral invasion

Our previous studies revealed that the 143-148 fragment of interleukin-1 receptor antagonist (IL-1 Ra) molecule with a Val-Thr-Lys-Phe-Tyr-Phe (VTKFYF) sequence inhibits the interleukin-1 (IL-1) interaction with its cellular receptor. The Val-Thr-Arg-Phe-Tyr-Phe (VTRFYF) sequence of the 322-327 fragment of the C-terminal domain of vaccinia virus protein related to the C10L vaccinia gene shows a very high homology to the 143-148 IL-1 Ra fragment, suggesting a similar inhibitory activity. To test this suggestion, we investigated the inhibitory activity of a series of synthetic peptides derived from 316 to 327 fragment of C10L on the interaction of IL-1 with its receptor. We also tested the peptides for their influence on the humoral and cellular immune response. The results indicate that biological activities of the C10L fragments are similar to those obtained for respective fragments of IL-1 Ra. The C-terminal domain of C10L protein can be easily folded into spatial structure similar to the crystallographic one of IL-1 Ra. Based on the crystallographic structure of IL-1 Ra, we constructed a 3-D model of the C10L protein. According to the model, the Val(322)-Asn(328) sequence is localized on the surface of the molecule and, therefore, it may be involved in the interactions with receptors. Our results indicate that the C10L viral protein can play an important role in vaccinia virus evasion of the host immune system. It may consist in the blockade of IL-1 receptors by the C10L protein, a homologue of the IL-1 Ra.

A convergent three-component total synthesis of the powerful immunosuppressant (-)-sanglifehrin a

The potent immunosuppressive agent (-)-sanglifehrin A (5), initially discovered in a soil sample from Malawi, has been synthesized in a highly convergent and stereocontrolled manner. The enantioselective approach relies on initial construction of the iodovinyl carboxylic acid 14, which is coupled to tripeptide 59 in advance of a key macrolactonization step that generates 61a. An alternative protocol that involves the linkage of 14 to 46 for possible construction of the large ring failed due to an inability to bring about a corresponding macrolactamization maneuver. An efficient means for elaborating the C26-N42 spirolactam western sector of 5 is also detailed. This requisite fragment was assembled through the proper adaptation of consecutive aldol tactics for construction of the nine stereogenic centers, six of which are contiguous. The first aldol process consisted of the tin triflate-mediated reaction of the aldehyde derived from 72 with enantiopure ketone 73 to generate the syn C36-C37 relationship resident in 75. Once the conversion of 75 to 78 had been completed, the attachment to ketone 66 was effected with (+)-DIPCl, thereby setting the C33-C34 relationship as anti. Once functional group modifications had given rise to 62, spirolactamization was achieved to deliver predominantly 94, thereby setting the stage for the acquisition of vinyl stannane 13 and its subsequent palladium-catalyzed Stille coupling to 61b. Controlled acidic hydrolysis completed the synthesis of 5. Other important features of the present route are addressed where relevant.