1
|
Player MR, Torrence PF. Synthesis and characterization of chimeric 2-5A-DNA oligonucleotides. ACTA ACUST UNITED AC 2008; Chapter 4:Unit 4.4. [PMID: 18428851 DOI: 10.1002/0471142700.nc0404s01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This unit provides protocols for the synthesis and characterization of 2-5A-antisense nucleic acids. These chimeric oligonucleotides consist of 2',5'-phosphodiester-linked oligoadenylates ligated to 3',5'-deoxyribonucleotides and are readily prepared using phosphoramidite chemistry on CPG solid supports. The 3',5'-deoxyribonucleotide functions as the antisense domain to target a given mRNA sequence, while the 2',5'-phosphodiester-linked oligoadenylate serves to locally activate 2-5A-dependent RNase L, causing the targeted sequence to be cleaved.
Collapse
Affiliation(s)
- M R Player
- Northern Arizona University, Flagstaff, Arizona, USA
| | | |
Collapse
|
2
|
Paranjape JM, Xu D, Kushner DM, Okicki J, Lindner DJ, Cramer H, Silverman RH, Leaman DW. Human telomerase RNA degradation by 2'-5'-linked oligoadenylate antisense chimeras in a cell-free system, cultured tumor cells, and murine xenograft models. Oligonucleotides 2006; 16:225-38. [PMID: 16978086 DOI: 10.1089/oli.2006.16.225] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Ribonuclease L (RNase L) is a latent single-stranded RNA-directed endoribonuclease that is activated on binding to short 2'-5'-linked oligoadenylates (2-5A), a feature that has led to its use in antisense therapeutic strategies. By attaching a 2-5A moiety to the 5' terminus of standard antisense oligonucleotides, it is possible to activate RNase L and guide it to specific RNAs for degradation. These 2-5A antisense chimeras have been used successfully to target a variety of cellular and viral RNAs. Telomerase is a nuclear ribonucleoprotein complex that elongates telomeric DNA and contributes to cellular immortalization. Telomerase is composed of a protein catalytic subunit and an RNA (hTR or TERC) component, both of which are critical for holoenzyme activity. We describe the characterization of 2-5A antisense chimeras targeting the hTR component of telomerase (2-5A antihTR). Newly designed 2-5A anti-hTR molecules were assayed for their abilities to selectively degrade hTR in a cell-free system. Of the five chimeras tested, one (RBI011) degraded hTR by 97%, and two others (RBI013 and RBI009) were also found to be highly active (73-76% degradation). The ability of transfected RBI011, and its homolog RBI254, to degrade hTR in cultured tumor cells was assessed by real-time RT-PCR. In these studies, RBI011 and RBI254 effectively degraded hTR in a variety of hTR-positive tumor cell lines. The hTR degradation studies were extended to growth assays to determine whether hTR ablation affected tumor cell viability or proliferation. RBI254 treatment resulted in reduced tumor cell viability over the course of 4-day growth assays, effects that were augmented by cotreatment with interferon-beta. To extend these results to an in vivo system, nude mice were implanted subcutaneously or orthotopically with hTR-positive prostate tumors and treated with RBI254. RBI254-treated mice exhibited enhanced tumor cell apoptosis and reduced tumor volume as compared with controls. These findings demonstrated the effectiveness of highly active forms of 2-5A antisense against hTR, and also highlight the usefulness of the cell-free system in predicting chimera efficacy before to inception of cell-based and in vivo studies.
Collapse
Affiliation(s)
- Jayashree M Paranjape
- Department of Cancer Biology and Immunology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | | | | | | | | | | | | | | |
Collapse
|
3
|
Cramer H, Rhea R, Okicki J, Yirava K, Silverman R. The use of triisopropylsilyl-oxymethyl (TOM) in the synthesis of anti-telomerase 2-5A antisense compound RBI 011. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2003; 22:1733-6. [PMID: 14565507 DOI: 10.1081/ncn-120023125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The 2-5A antisense compound RBI 011 targeting telomerase RNA was synthesized using the triisopropylsilyl-oxymethyl (TOM) group for the 3'-hydroxyl protection of 2',5'-linked RNA.
Collapse
|
4
|
Münch U, Chen L, Bayly SF, Torrence PF. Probing the activation site of ribonuclease L with new N6-substituted 2',5'-adenylate trimers. Bioorg Med Chem 2003; 11:2041-9. [PMID: 12670655 DOI: 10.1016/s0968-0896(03)00060-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
2-5A trimer [5'-monophosphoryladenylyl(2'-5')adenylyl(2'-5')adenosine] activates RNase L. While the 5'-terminal and 2'-terminal adenosine N(6)-amino groups play a key role in binding to and activation of RNase L, the exocyclic amino function of the second adenylate (from the 5'-terminus) plays a relatively minor role in 2-5A's biological activity. To probe the available space proximal to the amino function of the central adenylate of 2-5A trimer during binding to RNase L, a variety of substituents were placed at that position. To accomplish this, the convertible building block 5'-O-dimethoxytrityl-3'-O-(tert-butyldimethylsilyl)-6-(2,4-dinitrophenyl)thioinosine 2'-(2-cyanoethylN,N-diisopropylphosphoramidite) was prepared as a synthon to introduce 6-(2,4-dinitrophenyl)thioinosine into the middle position of the 2-5A trimer during automated synthesis. Post-synthetic treatment with aqueous amines transformed the (2,4-dinitrophenyl)thioinosine into N(6)-substituted adenosines. Assays of these modified trimers for their ability to bind and activate RNase L showed that activation activity could be retained, albeit with some sacrifice compared to unmodified p5'A2'p5'A2'p5'A. Thus, the spatial domain about this N(6)-amino function could be available for modifications to enhance the biological potency of 2-5A analogues and to ligate 2-5A to targeting vehicles such as antisense molecules.
Collapse
Affiliation(s)
- Ursula Münch
- Section on Biomedical Chemistry, Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0805, USA
| | | | | | | |
Collapse
|
5
|
Torrence PF, Powell LD. The quest for an efficacious antiviral for respiratory syncytial virus. Antivir Chem Chemother 2002; 13:325-44. [PMID: 12718405 DOI: 10.1177/095632020201300601] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Respiratory syncytial virus (RSV) continues as an emerging infectious disease not only among infants and children, but also for the immune-suppressed, hospitalized and the elderly. To date, ribavirin (Virazole) remains the only therapeutic agent approved for the treatment of RSV. The prophylactic administration of palivizumab is problematic and costly. The quest for an efficacious RSV antiviral has produced a greater understanding of the viral fusion process, a new hypothesis for the mechanism of action of ribavirin, and a promising antisense strategy combining the 2'-5' oligoadenylate antisense (2-5A-antisense) approach and RSV genomics.
Collapse
Affiliation(s)
- Paul F Torrence
- Department of Chemistry, Northern Arizona University, Flagstaff, Ariz., USA.
| | | |
Collapse
|
6
|
Verheijen JC, Chen L, Bayly SF, Torrence PF, van der Marel GA, van Boom JH. Synthesis and RNAse L binding and activation of a 2-5A-(5')-DNA-(3')-PNA chimera, a novel potential antisense molecule. NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS 2000; 19:1821-30. [PMID: 11200276 DOI: 10.1080/15257770008045463] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Fully automated solid-phase synthesis gave access to a hybrid in which 5'-phosphorylated-2'-5'-linked oligoadenylate (2-5A) is connected to the 5'-terminus of DNA which, in turn, is linked at the 3'-end to PNA [2-5A-(5')-DNA-(3')-PNA chimera]. This novel antisense molecule retains full RNase L activation potency while suffering only a slight reduction in binding affinity.
Collapse
Affiliation(s)
- J C Verheijen
- Leiden Institute of Chemistry, Gorlaeus Laboratories, The Netherlands
| | | | | | | | | | | |
Collapse
|
7
|
Kumar P, Takaku H. Properties of mixed backbone oligonucleotides containing 3'-O-methyl ribonucleosides. Bioorg Med Chem Lett 1999; 9:2515-20. [PMID: 10498199 DOI: 10.1016/s0960-894x(99)00414-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Oligonucleotides containing 3'-O-methyl ribonucleosides were synthesized, and their thermal stabilities and global conformations with RNA and DNA have been studied. The duplexes displayed lower T(m) values as compared to the unmodified ones, and adopted A-conformations. Furthermore, they are not a substrate for RNase H, are slightly resistant to snake venom phosphodiesterase, and are not cleaved by nuclease S 1.
Collapse
Affiliation(s)
- P Kumar
- High Technology Research Center, Chiba Institute of Technology, Narashino, Japan
| | | |
Collapse
|
8
|
The 3rd Annual NIH Symposium on Therapeutic Oligonucleotides. Bethesda, Maryland, USA. December 4, 1998. Abstracts. ANTISENSE & NUCLEIC ACID DRUG DEVELOPMENT 1999; 9:359-431. [PMID: 10498436 DOI: 10.1089/oli.1.1999.9.359] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
9
|
Abstract
Recent work has demonstrated that the activity of a ubiquitous cellular enzyme, ribonuclease L (RNase L), can be harnessed to cleave targeted RNA species. Activation of RNase L is dependent on the presence of 2',5'-linked oligoadenylates (2-5A), usually produced by cells infected with viruses. By conjugating synthetic 2-5A to specific antisense compounds, it is now possible to selectively degrade RNAs in an RNase L-dependent manner, thereby providing an alternative to RNase H-dependent approaches. In this summary, we provide an updated description of the synthesis procedure for constructing these chimeric 2-5A antisense molecules. Examples of successful applications of the 2-5A antisense strategy are described, along with some of the procedures involved in those studies. Several methods are also provided for optimizing compound uptake and analyzing their effects on cells. Finally, we discuss the current body of evidence that supports the contention that RNase L is indeed the primary mediator of 2-5A antisense effects and the possible implications that this has on the future of this therapeutic approach.
Collapse
Affiliation(s)
- D W Leaman
- Gemini Technologies Inc., 11,000 Cedar Avenue, Suite 140, Cleveland, Ohio 44106, USA.
| | | |
Collapse
|
10
|
Cramer H, Player MR, Torrence PF. Discrimination between ribonuclease H- and ribonuclease L-mediated RNA degradation by 2'-O-methylated 2-5A-antisense oligonucleotides. Bioorg Med Chem Lett 1999; 9:1049-54. [PMID: 10230638 DOI: 10.1016/s0960-894x(99)00134-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
2',5'-Oligoadenylate (2-5A) antisense chimeric oligonucleotides were synthesized containing varying 2'-O-methyl-ribonucleotide substitution patterns in the antisense domain. The ability of these composite oligonucleotides to mediate RNase H- and RNase L-catalyzed RNA degradation showed that these two enzymes have different activation requirements.
Collapse
Affiliation(s)
- H Cramer
- Section on Biomedical Chemistry, Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0805, USA
| | | | | |
Collapse
|
11
|
Barnard DL, Sidwell RW, Xiao W, Player MR, Adah SA, Torrence PF. 2-5A-DNA conjugate inhibition of respiratory syncytial virus replication: effects of oligonucleotide structure modifications and RNA target site selection. Antiviral Res 1999; 41:119-34. [PMID: 10320045 DOI: 10.1016/s0166-3542(99)00005-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
To define more fully the conditions for 2-5A-antisense inhibition of respiratory syncytial virus (RSV), relationships between 2-5A antisense oligonucleotide structure and the choice of RNA target sites to inhibition of RSV replication have been explored. The lead 2-5A-antisense chimera for this study was the previously reported NIH8281 that targets the RSV M2 RNA. We have confirmed and extended the earlier study by showing that NIH8281 inhibited RSV strain A2 replication in a variety of antiviral assays, including virus yield reduction assays performed in monkey (EC90 = 0.02 microM) and human cells (EC90 = microM). This 2-5A-antisense chimera also inhibited other A strains, B strains and bovine RSV in cytopathic effect inhibition and Neutral Red Assays (EC50 values = 0.1-1.6 microM). The 2'-O-methylation modification of NIH8281 to increase affinity for the complementary RNA and provide nuclease resistance, the introduction of phosphothioate groups in the antisense backbone to enhance resistance to exo- and endonucleases, and the addition of cholesterol to the 3'-terminus of the antisense oligonucleotide to increase cellular uptake, all resulted in loss of activity. Of the antisense chimeras targeting other RSV mRNAs (NS1, NS2, P, M. G, F, and L), only those complementary to L mRNA were inhibitory. These results suggest that lower abundance mRNAs may be the best targets for 2-5A-antisense; moreover, the active 2-5A antisense chimeras in this study may serve as useful guides for the development of compounds with improved stability, uptake and anti-RSV activity.
Collapse
Affiliation(s)
- D L Barnard
- Institute For Antiviral Research, Utah State University, Logan 84322-5600, USA
| | | | | | | | | | | |
Collapse
|
12
|
Player MR, Torrence PF. Phosphorothioate oligodeoxyribonucleotides inhibit ribonuclease L thereby disabling a mechanism of interferon action. Bioorg Med Chem Lett 1999; 9:891-4. [PMID: 10206556 DOI: 10.1016/s0960-894x(99)00099-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Phosphorothioate oligodeoxyribonucleotides were found to be inhibitors of the 2-5A-dependent RNase L. Inhibitory potency depended upon the chain length of the phosphorothioate oligonucleotide and was dependent on the phosphorothioate substitution pattern, but was not substantially base-dependent.
Collapse
Affiliation(s)
- M R Player
- Section on Biomedical Chemistry, Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0805, USA
| | | |
Collapse
|
13
|
2′,5′-Oligoadenylate-Antisense Chimeras Cause RNase L to Selectively Degrade bcr/abl mRNA in Chronic Myelogenous Leukemia Cells. Blood 1998. [DOI: 10.1182/blood.v92.11.4336] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractWe report an RNA targeting strategy, which selectively degrades bcr/abl mRNA in chronic myelogenous leukemia (CML) cells. A 2′,5′-tetraadenylate activator (2-5A) of RNase L was chemically linked to oligonucleotide antisense directed against either the fusion site or against the translation start sequence in bcr/abl mRNA. Selective degradation of the targeted RNA sequences was demonstrated in assays with purified RNase L and decreases of p210bcr/abl kinase activity levels were obtained in the CML cell line, K562. Furthermore, the 2-5A-antisense chimeras suppressed growth of K562, while having substantially reduced effects on the promyelocytic leukemia cell line, HL60. Findings were extended to primary CML cells isolated from bone marrow of patients. The 2-5A-antisense treatments both suppressed proliferation of the leukemia cells and selectively depleted levels of bcr/abl mRNA without affecting levels of β-actin mRNA, determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The specificity of this approach was further shown with control oligonucleotides, such as chimeras containing an inactive dimeric form of 2-5A, antisense lacking 2-5A, or chimeras with altered sequences including several mismatched nucleotides. The control oligonucleotides had either reduced or no effect on CML cell growth and bcr/abl mRNA levels. These findings show that CML cell growth can be selectively suppressed by targeting bcr/abl mRNA with 2-5A-antisense for decay by RNase L and suggest that these compounds should be further explored for their potential as ex vivo purging agents of autologous hematopoietic stem cell transplants from CML patients.
Collapse
|
14
|
2′,5′-Oligoadenylate-Antisense Chimeras Cause RNase L to Selectively Degrade bcr/abl mRNA in Chronic Myelogenous Leukemia Cells. Blood 1998. [DOI: 10.1182/blood.v92.11.4336.423a06_4336_4343] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report an RNA targeting strategy, which selectively degrades bcr/abl mRNA in chronic myelogenous leukemia (CML) cells. A 2′,5′-tetraadenylate activator (2-5A) of RNase L was chemically linked to oligonucleotide antisense directed against either the fusion site or against the translation start sequence in bcr/abl mRNA. Selective degradation of the targeted RNA sequences was demonstrated in assays with purified RNase L and decreases of p210bcr/abl kinase activity levels were obtained in the CML cell line, K562. Furthermore, the 2-5A-antisense chimeras suppressed growth of K562, while having substantially reduced effects on the promyelocytic leukemia cell line, HL60. Findings were extended to primary CML cells isolated from bone marrow of patients. The 2-5A-antisense treatments both suppressed proliferation of the leukemia cells and selectively depleted levels of bcr/abl mRNA without affecting levels of β-actin mRNA, determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The specificity of this approach was further shown with control oligonucleotides, such as chimeras containing an inactive dimeric form of 2-5A, antisense lacking 2-5A, or chimeras with altered sequences including several mismatched nucleotides. The control oligonucleotides had either reduced or no effect on CML cell growth and bcr/abl mRNA levels. These findings show that CML cell growth can be selectively suppressed by targeting bcr/abl mRNA with 2-5A-antisense for decay by RNase L and suggest that these compounds should be further explored for their potential as ex vivo purging agents of autologous hematopoietic stem cell transplants from CML patients.
Collapse
|
15
|
Player MR, Barnard DL, Torrence PF. Potent inhibition of respiratory syncytial virus replication using a 2-5A-antisense chimera targeted to signals within the virus genomic RNA. Proc Natl Acad Sci U S A 1998; 95:8874-9. [PMID: 9671772 PMCID: PMC21170 DOI: 10.1073/pnas.95.15.8874] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The 2-5A system is a recognized mechanistic component of the antiviral action of interferon. Interferon-induced 2-5A synthetase generates 2-5A, which, in turn, activates the latent constitutive RNase L that degrades viral RNA. Chemical conjugation of 2-5A to an antisense oligonucleotide can target the 2-5A-dependent RNase L to the antisense-specified RNA and effect its selective destruction. Such a 2-5A-antisense chimera (NIH351) has been developed that targets a consensus sequence within the respiratory syncytial virus (RSV) genomic RNA. NIH351 was 50- to 90-fold more potent against RSV strain A2 than was ribavirin, the presently approved drug for clinical management of RSV infection. It was similarly active against a variety of RSV strains of both A and B subgroups and possessed a cell culture selectivity index comparable to ribavirin. In addition, the anti-RSV activity of NIH351 was shown to be virus-specific and a result of a true antisense effect, because a scrambled nucleotide sequence in the antisense domain of NIH351 caused a significant decrease in antiviral activity. The 2-5A system's RNase L was implicated in the mechanism of action of NIH351 because a congener with a disabled 2-5A moiety was of greatly reduced anti-RSV effectiveness. These findings represent an innovative approach to the control of RSV replication.
Collapse
Affiliation(s)
- M R Player
- Section on Biomedical Chemistry, Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0805, USA
| | | | | |
Collapse
|
16
|
Player MR, Maitra RK, Silverman RH, Torrence PF. Targeting RNase L to human immunodeficiency virus RNA with 2-5A-antisense. Antivir Chem Chemother 1998; 9:225-31. [PMID: 9875401 DOI: 10.1177/095632029800900303] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In an attempt to develop a lead for the application of 2-5A-antisense to the targeted destruction of human immunodeficiency virus (HIV) RNA, specific target sequences within the HIV mRNAs were identified by analysis of the theoretical secondary structure. 2-5A-antisense chimeras were chosen against a total of 11 different sequences: three in the gag mRNA, three in the rev mRNA and five in the tat mRNA. 2-5A-antisense chimera synthesis was accomplished using solid-phase phosphoramidite chemistry. These chimeras were evaluated for their activity in a cell-free assay system using purified recombinant human RNase L to effect cleavage of 32P-labelled RNA transcripts of plasmids derived from HIV NL4-3. This screening revealed that of the three 2-5A-antisense chimeras targeted against gag mRNA, only one had significant HIV RNA cleavage activity, approximately 10-fold-reduced compared to the parent 2-5A tetramer and comparable to that reported for the prototypical 2-5A-anti-PKR chimera, targeted against PKR mRNA. The cleavage activity of this chimera was specific, since a scrambled antisense domain chimera and a chimera without the key 5'-monophosphate moiety were both inactive. The 10 other 2-5A-antisense chimeras against tat and rev had significantly less activity. These results imply that HIV gag RNA, like PKR RNA and a model HIV tat-oligoA-vif RNA, can be cleaved using the 2-5A-antisense approach. The results further imply that not all regions of a potential RNA target are accessible to the 2-5A-antisense approach.
Collapse
Affiliation(s)
- M R Player
- Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0805, USA
| | | | | | | |
Collapse
|