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PubMed1987

Phosphorothioate analogs of oligodeoxynucleotides: inhibitors of replication and cytopathic effects of human immunodeficiency virus.

Nuclease-resistant phosphorothioate analogs of certain oligodeoxynucleotides have been tested in vitro as antiviral agents against human immunodeficiency virus (HIV) in human T cells. Phosphorothioate analogs complementary to HIV sequences, as well as noncomplementary analogs including homooligomers, exhibited potent antiviral activity. The antiviral activity was related to the base composition of the analogs, and longer phosphorothioates were more effective than shorter ones. A 28-mer phosphorothioate oligodeoxycytidine (S-dC28) at a concentration of 1 microM exhibited potent antiviral activity and inhibited de novo viral DNA synthesis as shown by Southern blot analysis. However, S-dC28 failed to inhibit gag expression in chronically infected T cells assessed by immunofluorescent assay at concentrations up to 25 microM. An N3-methylthymidine-containing phosphorothioate analog, which does not hybridize efficiently in vitro to complementary normal DNA, showed no antiviral activity. A 14-mer phosphorothioate oligodeoxycytidine (S-dC14) synergistically enhanced the antiviral activity of 2',3'-dideoxyadenosine, an anti-HIV nucleoside. Therefore, phosphorothioate analogs of oligodeoxynucleotides could represent a unique class of experimental therapeutic agents against the acquired immunodeficiency syndrome and related diseases. However, their mechanism of action is likely to be complex.

Base Sequence↗
PubMed1994

Identification of phosphate oxygens that are important for self-cleavage activity of the HDV ribozyme by phosphorothioate substitution interference analysis.

A phosphorothioate substitution interference assay was used to investigate the role of the pro-Rp oxygens of phosphate groups in the self-cleavage reaction of the genomic human hepatitis delta virus (HDV) ribozyme. Incorporation of several different phosphorothioates (NTP alpha S) into the HDV ribozyme inhibited the self-cleavage activity. Incorporation of uridine 5' phosphorothioate or adenosine 5' phosphorothioate maintained 72% of the original self-cleavage activity whereas incorporation of guanosine 5' phosphorothioate or cytosine 5' phosphorothioate into the precursor reduced self-cleavage activity to about 20% in each case. Using partially substituted phosphorothioate-modified transcripts, we identified the pro-Rp oxygens that are important for the ribozyme activity, and they are located at positions 0, 1, 4, 5, 21, 24, 25, 27, 28, 30-34, 40, 43 and 75. In particular, the pro-Rp oxygens at positions 0, 1 and 21 are appear to be critical for the self-cleavage activity of the HDV ribozyme.

Base Sequence↗
PubMed1983

Interaction of sn-glycerol 3-phosphorothioate with Escherichia coli: effect on cell growth and metabolism.

sn-Glycerol 3-phosphorothioate was found to be bacteriocidal to strains of Escherichia coli which have a functional sn-glycerol 3-phosphate transport system. This effect was manifest in strains 7 and 8, which are constitutive mutants for the utilization and transport of sn-glycerol 3-phosphate (glpRc2). Strain E15, which is considered to be wild type for the glycerol phosphate functional units, was affected by the phosphorothioate analog only under conditions that are known to induce the transport system for sn-glycerol 3-phosphate. In addition, another strain of E. coli, strain 6, which is isogenic with strain E15 but has an impaired sn-glycerol 3-phosphate transport system (glpT13), was not affected by similar concentrations of sn-glycerol 3-phosphorothioate. Transport studies in which [3H]glycerol phosphate and its phosphorothioate analog were used demonstrated that the latter compound was taken up via the specific active transport system for sn-glycerol 3-phosphate; the Km values were 9 and 11 microM, respectively. The rates of macromolecular synthesis were found to be inhibited severely by sn-glycerol 3-phosphorothioate at a concentration at which sn-glycerol 3-phosphate had no effect (5 microM). At a lower concentration of the analog (0.5 microM), the rates of protein synthesis and RNA synthesis (52 and 58% below control values after 90 min, respectively) were more sensitive than the rates of DNA synthesis and cell wall synthesis (18% below control values after 3 h for DNA; transient decrease in the cell wall values after 90 min). The levels of the nucleoside triphosphates were not affected by the presence of the phospholipid precursor or its analog at a concentration of 5 microM. The phospholipid composition was significantly altered in the presence of bacteriocidal concentrations (5 microM) of sn-glycerol 3-phosphorothioate. The amount of phosphatidylglycerol in the membranes decreased from 13.5 to 3.5%. Concomitant with this decrease in phosphatidylglycerol content was a fourfold increase in the 32P content of cardiolipin (from 6.8 to 24.2%), whereas the phosphatidylethanolamine content showed only a minor reduction (8%) after 3 h. The rates of synthesis of all of the phospholipids decreased in the presence of 5 microM sn-glycerol 3-phosphorothioate, with the most significant effects observed for phosphatidylglycerol (63% after 3 h). Phosphatidylglycerol showed increased rates of turnover after 90 min (21%) and 3 h (11%), with concomitant increases in the levels of cardiolipin of more than twofold. Our data suggest that a considerably greater proportion of phosphatidylglycerol turnover may be recover in cardiolipin than is metabolized via other pathways (e.g., the membrane-derived oligosaccharide pathway).

Biological Transport↗
PubMed1986

Stereoconfiguration markedly affects the biochemical and biological properties of phosphorothioate analogs of 2-5A core, (A2'p5')2A.

The diester bonds of phosphorothioate trimer analogs of (A2'p5')2A (2-5A core) of the Sp stereoconfiguration were found to be extremely stable to hydrolysis by both serum and cellular phosphodiesterases. The corresponding Rp isomers, although still more stable than parent ppp(A2'p5')2A (2-5A), were significantly more susceptible to enzymatic hydrolysis than were the Sp isomers. Utilization of these novel 2-5A trimer isomers containing various combinations of Sp or Rp configurations at the internucleotidic phosphorothioate linkages revealed a further specificity of this enzymatic hydrolysis. Thus, the stereoconfiguration of the bond adjacent to the one undergoing hydrolysis influenced the rate of enzymatic hydrolysis, as well as did the chain length of the oligomer. The most stable trimer analog, which contained both internucleotide phosphorothioate linkages of the Sp configuration, had a half-life of 30 days in serum, which is a 1500-fold increase over that of parent 2-5A core. This is the first report on biochemical stability of an oligonucleotide containing more than one phosphorothioate linkage of the Sp configuration and is the first demonstration that a phosphorothioate internucleotide bond of the Sp configuration can increase the enzymatic stability of an adjacent phosphorothioate bond. In marked contrast to all previous 2-5A core analogs of increased stability, the activity (antiproliferative and antiviral) of the stable phosphorothioate 2-5A core analogs was obtained with the intact trimer, i.e., it was not attributed to antimetabolite degradation products.

Adenine Nucleotides↗
PubMed1999

Polymer solution-filled column for the analysis of antisense phosphorothioates by capillary electrophoresis.

A capillary electrophoresis (CE) column filled with 13% poly(ethylene glycol) (PEG) solution is demonstrated to resolve different lengths of antisense phosphorothioates in 100 mM Tris-borate (pH 9.0) buffer containing 30% formamide at 50 degrees C. Two sets of mixtures composed of 15-20 mers of either antisense phosphorothioate or phosphodiester oligonucleotides were synthesized based on a sequence of the antisense orientation directed against DNA-methyltransferase (denoted as MT-AS) and were used as model compounds. It was found that column coating reduced electroosmotic flow, as well as wall adsorption, and led to the separation of both phosphorothioate and phosphodiester molecules. Substantial peak broadening, however, specifically occurred to the phosphorothioates and was reduced statisfactorily by the addition of formamide into the buffer solution, raising the temperature, and raising the pH value. Under experimental conditions, a linear relationship between the migration time and the base number was observed, indicating that no peak compression artifacts existed. Without tedious pretreatment, antisense phosphorothioates were spiked into human serum, followed by water dilution, and then directly injected into the column. Separation of different lengths of phosphorothioates was observed using pressure injection, which did not suffer from injection bias.

Electrophoresis, Capillary↗
PubMed1997

Phosphorothioate oligodeoxynucleotides: large-scale synthesis and analysis, impurity characterization, and the effects of phosphorus stereochemistry.

Large-scale synthesis of phosphorothioate oligodeoxynucleotides on Tentagel using a 'batch mode' synthesizer and beta-cyanoethyl phosphoramidite coupling followed by sulfurization with bis(O,O-diisopropoxy phosphinothioyl) disulfide (S-tetra) provides stepwise yields of 98-99% and results in phosphorothioate oligodeoxynucleotides that are 93-97% pure, as determined by PAGE, after reverse-phase high performance liquid chromatography (RP-HPLC) and 'downstream' processing. The purity of phosphorothioate oligodeoxynucleotides synthesized on Tentagel is significantly higher than those synthesized on controlled pore glass. Electrospray ionization mass spectrometry of the n-1 impurity isolated by preparative PAGE was used to establish that the n-1 impurity is a heterogeneous mixture of all possible single-deletion sequences, relative to the parent phosphorothioate oligodeoxynucleotide, and results from minor, though repetitive, imperfections in the synthesis cycle. Acid-catalysed depurination was found to occur both during the synthesis and during the post-synthesis detritylation, following RP-HPLC. Studies of hybridization affinity and biological mechanism of action using independently synthesized n-1 phosphorothioate oligodeoxynucleotides relative to the 15 mer LR-3280 showed that, in this case, the majority of the n-1 sequences had more than a 10 degrees C decrease in melting temperature with sense RNA compared to the n-mer, and they did not cause detectable cleavage of RNA by RNase H in HL-60 human promyelocytic leukaemia cells. P stereoregular phosphorothioate oligodeoxynucleotides are not significantly more active than their stereorandom counterparts and thus their use in clinical studies seems unwarranted.

Humans↗
PubMed1984

Morphological alterations of rat lung bronchiolar epithelium produced by various trialkyl phosphorothioates.

A single oral administration of O, O, S-trimethyl phosphorothioate (OOS-Me), an impurity in widely used organophosphorus insecticides, causes delayed toxicity (delayed death) which is accompanied by morphological changes in the bronchiolar epithelium of rat lungs. A series of simple O,O-dimethyl and O,O-diethyl S-alkyl phosphorothioate esters, which induce delayed toxicity, were examined for their effect on rat bronchiolar epithelium. The structural analogues synthesized and tested include O, O-dimethyl S-ethyl phosphorothioate, O,O-dimethyl S-isopropyl phosphorothioate, O,O,S-triethyl phosphorothioate, and O,O-diethyl S-methyl phosphorothioate. The present investigation demonstrated that these analogues of OOS-Me which cause delayed toxicity produce body weight loss, accompanied by morphological alterations of terminal bronchiolar epithelium, i.e. loss of the apical bulge of non-ciliated Clara cells. Another impurity which produces delayed toxicity, O,S,S-trimethyl phosphorodithioate, was also capable of producing similar effects at near the LD50 level.

Administration, Oral↗
PubMed2005

Sequence confirmation of synthetic phosphorothioate oligodeoxynucleotides using Sanger sequencing reactions in combination with mass spectrometry.

A protocol relying on Sanger sequencing reactions in combination with mass spectrometry (MS) for sequence confirmation of antisense phosphorothioate oligodeoxynucleotides is described. In this procedure, synthetic phosphorothioate oligodeoxynucleotides are used as reverse primers for extension of matched templates with enough length (approximately 150-300 bp) for well-established Sanger sequencing. Because the complementary strand of modified primer is used directly for sequencing primer extension, the base order shown in the sequencing result is reversely complementary to phosphorothioate oligodeoxynucleotide. This sequencing method can be applied not only to phosphorothioate oligodeoxynucleotides with different lengths (13-21 mer) and base composition but also to sequences with bases' switch, deletion, or insertion. In addition, modified primers incorporate the 5' end of polymerase chain reaction (PCR) products conveying the characters of phosphorothioate modification. The method requires only common reagents and instruments and so is better suited to routine sequence analysis in quality control of phosphorothioate antisense drugs.

Base Sequence↗
PubMed1999

Effect of phosphorothioate modifications on the ability of GTn oligodeoxynucleotides to specifically recognize single-stranded DNA-binding proteins and to affect human cancer cellular growth.

We have previously identified phosphodiester oligonucleotides exclusively made of G and T bases, named GTn, that significantly inhibit human cancer cell growth and recognize specific nuclear single-stranded DNA binding proteins. We wished to examine the ability of the modified GTn oligonucleotides with different degrees of phosphorothioate modifications to bind specifically to the same nuclear proteins recognized by the GTn phosphodiester analogues and their cytotoxic effect on the human T-lymphoblastic CCRF-CEM cell line. We showed that the full phosphorothioate GTn oligonucleotide was neither able to specifically recognize those nuclear proteins, nor cytotoxic. In contrast, the 3'-phosphorothioate-protected GTn oligonucleotides can maintain the specific protein-binding activity. The end-modified phosphorothioate oligonucleotides were also able to elicit the dose-dependent cell growth inhibition effect, but a loss in the cytotoxic ability was observed increasing the extent of sulphur modification of the sequences. Our results indicate that phosphorothioate oligonucleotides directed at specific single-stranded DNA-binding proteins should contain a number of phosphorothioate end-linkages which should be related to the length of the sequence, in order to maintain the same biological activities exerted by their phosphodiester analogues.

Base Sequence↗
PubMed1999

Labeling of phosphorothioate antisense oligonucleotides with yttrium-90.

Novel yttrium-90 (90Y)-labeled phosphorothioate antisense oligonucleotides were designed as a potential targeted radionuclide therapeutic agent for malignant tumors. A 15-mer phosphorothioate antisense oligonucleotide, which was complementary to the translation start region of the N-myc oncogene mRNA, was conjugated with isothiocyanobenzyl ethylenediamine tetraacetic acid (SCN-Bn-EDTA), via a C-5-substituted deoxyuridine that had replaced a thymine in the oligonucleotide, and was then labeled with 90Y-acetate. Following purification, the radiochemical purity of the 90-Y-Bn-EDTA-phosphorothioate antisense oligonucleotides was estimated by 2.0% agarose gel electrophoresis, and the specific hybridization of 90Y-Bn-EDTA-phosphorothioate antisense oligonucleotide to a phosphorodiester sense oligonucleotide was investigated by 20% polyacrylamide gel electrophoresis in a cell-free system. Radiochemical purity was 98.7 +/- 0.4% at 72 h after labeling and 90.3 +/- 0.9% after 72-h incubation with human normal serum. The 90Y-Bn-EDTA-phosphorothioate antisense oligonucleotide hybridized specifically to a complementary phosphorodiester sense oligonucleotide. In conclusion, phosphorothioate antisense oligonucleotides can be labeled stably with 90Y using SCN-Bn-EDTA without loss of hybridization properties.

Blood Physiological Phenomena↗
PubMed2000

Impact of phosphorothioate substitutions on the thermodynamic stability of an RNA GAAA tetraloop: an unexpected stabilization.

This study analyzes the impact of phosphorothioate substitutions on the thermodynamic stability of a 12-nt RNA hairpin containing a (5')GAAA(3') tetraloop. The thermodynamic consequences of stereospecific phosphorothioate substitutions 5' to each adenosine in the loop region are measured using optical melting and calorimetry experiments. Surprisingly, a single stereospecific phosphorothioate substitution 5' to the second adenosine of the tetraloop, R(p)-A7, results in a stabilization corresponding to a Delta(DeltaG(37)(degrees)(C)) of approximately -2.9 kcal mol(-1) (0.1 M NaCl) when compared with that of an unmodified sample. Five other phosphorothioate-substituted samples did not show significant thermodynamic differences in comparison with the unsubstituted samples. Addition of Mg(2+) to all of the hairpins studied results in increased t(m's) that are fit with a general electrostatic model to a dissociation constant of K(d)(Mg(2+)) approximately 2-3 mM (0.1 M NaCl). The R(p)-A7 phosphorothioate-substituted hairpin showed an unusual decrease in t(m) and apparent increase in enthalpy of unfolding upon addition of Cd(2+). These results may impact the interpretation of interference mapping experiments that use phosphorothioate substitutions to characterize RNAs in solution.

Cadmium↗
PubMed1990

Phosphorothioate analogues of (2'-5')(A)4: agonist and antagonist activities in intact cells.

Metabolically stable phosphorothioate tetramer analogues of (2'-5')(A)n with Rp and/or Sp chirality in the 2'-5'-phosphodiester linkages constitute a new class of antiviral agents since they mimic the effects of interferons. Three of the diastereomeric 5'-monophosphates (i.e., pRpRpRp, pSpRpRp, and pRpSpSp) bind to and activate RNase L from extracts of HeLa cells. However, the pSpSpSp (2'-5')-(A)4-phosphorothioate is unique in that it binds to, but cannot activate, RNase L to cleave rRNA. When microinjected into the cytoplasm of HeLa cells followed by virus infection, the pRpRpRp, pSpRpRp, and pRpSpSp (2'-5')(A)4-phosphorothioates demonstrate antiviral activity, as does (2'-5')(A)4ox-red, an active (2'-5')(A)n analogue. When microinjected simultaneously with (2'-5')(A)nox-red, an active the pSpSpSp (2'-5')(A)4-phosphorothioate inhibits activation of RNase L in HeLa cells, thereby blocking direct protection of vesicular stomatitis virus. The agonist and antagonist properties of pRpRpRp and pSpSpSp, respectively, are transient probably as a consequence of the hydrolysis of the 5'-monophosphate and formation of the less active (2'-5')(A)4-phosphorothioate cores. The possible use of these (2'-5')(A)4-phosphorothioates as tools for dissecting the biological significance of the (2'-5')(A)n system or in antiviral chemotherapy is discussed.

Antiviral Agents↗
PubMed1979

S-2,omega-Diaminoalkyl dihydrogen phosphorothioates as antiradiation agents.

To enable further structure-activity comparisons among radioprotective phosphorothioates, S-2,omega-diaminoalkyl dihydrogen phosphorothioates were synthesized from L-2,4-diaminobutyric acid, L-ornithine, L-lysine, and DL-2,7-diaminoheptanoic acid as homologues of S-2,3-diaminopropyl dihydrogen phosphorothioate (4) and as isomeric analogues of S-2-[(omega-aminoalkyl)amino]ethyl dihydrogen phosphorothioates (e.g., 1). The preferred route that evolved from exploratory trials retained optical activity and involved the reduction of methyl 2,omega-bis(benzoylamino)alkanoates with lithium borohydride, debenzoylation-bromodehydroxylation, and reaction of the resulting 1-(bromomethyl)-1,omega-alkanediamine dihydrobromides with trisodium phosphorothioate. The products of an alternative route that involved the reduction of phthaloylated intermediates with sodium borohydride were racemic. Exploratory conversions of N-(omega-alkenyl)phthalimides failed to provide suitable precursors of the target compounds. In terms of a protective index, these homologues were significantly more radioprotective than the parent phosphorothioate 4 when administered intraperitoneally to mice prior to whole-body gamma irradiation. The homologues derived from L-lysine also showed good peroral activity. No apparent difference was observed in the protection afforded by optically active homologues and the corresponding racemates.

Animals↗
PubMed1994

Antisense oligodeoxynucleotides for in vivo targeting of corticotropin-releasing hormone mRNA: comparison of phosphorothioate and 3'-inverted probe performance.

Antisense DNA has been successfully used in vivo to selectively inhibit expression of proteins in the brain. However, stressful side effects after oligodeoxynucleotide (ODN) application have been observed, but not carefully characterized. An attempt was made to establish an animal model of reduced corticotropin-releasing hormone (CRH) activity, using antisense DNA corresponding to the start coding region of rat CRH mRNA with either 3'-3' inverted internucleotidic linkage or with all-phosphorothioate modification. Probes were injected intracerebroventricularly (i.c.v.) twice, 12-hours apart. After phosphorothioate sense ODN injection serum corticosterone levels were significantly elevated compared to vehicle (aCSF) or 3'-3' end inverted sense ODN controls. This increase was also apparent but less pronounced in phosphorothioate antisense treated animals compared with the corresponding sense group. After exposure to ether vapour, both phosphorothioate and inverted antisense ODN injected rats showed a markedly diminished stress induced corticosterone secretion compared to the corresponding sense or vehicle injected rats. These results indicate that a) stress induced corticosterone release is suppressed by i.c.v. CRH antisense treatment, b) phosphorothioate ODNs exert an unspecific, chronic stress-like activation of the HPA-axis and c) this effect is partly inhibited by phosphorothioate antisense directed against CRH mRNA.

Animals↗
PubMedDate not supplied

Toxicological properties of phosphorothioate and related esters present as impurities in technical organophosphorus insecticides.

O,O,S-Trimethyl phosphorothioate, an impurity in several technical organophosphorus insecticides, when administered orally to rats at single doses as low as 15 mg/kg caused delayed mortality, with death occurring 4-22 d after treatment. Delayed toxic signs were also observed in mice, but mice were generally less sensitive than rats. O,O,S-triethyl phosphorothioate and O,S,S-trimethyl phosphorodithioate induced the same signs of intoxication at slightly higher doses. Rats treated with O,O,S-trimethyl phosphorothioate refused food and water within 24 h after treatment and did not eat or drink until the time of death. Neither injection of nutrient solution nor atropine served to reduce or block intoxication. However, the isomeric O,O,O-trimethyl phosphorothioate was a potent antagonist of the toxicity of O,O,S-trimethyl phosphorothioate. As little as 1% of the O,O,O-trimethyl isomer protected rats from the intoxicating effects of the O,O,S-trimethyl isomer at doses as high as 200 mg/kg. Rat serum carboxylesterase and cholinesterase were inhibited for prolonged periods after a single oral dose of O,O,S-trimethyl phosphorothioate, but the duration of inhibition was significantly less when the toxicant contained 1% O,O,O-trimethyl isomer.

Animals↗
PubMedDate not supplied

Toxicological properties of O,O,S-trialkyl phosphorothioates.

The effect of atropine, 2-pyridine aldoxime methiodide (2-PAM), and several O,O,O-trialkylphosphorothioates on poisoning of rats by a series of O,O-dimethyl and O,O-diethyl S-alkyl phosphorothioates was investigated. Atropine and 2-PAM successfully protected rats treated with O,O-diethyl S-n-propyl and S-i-propyl phosphorothioates, while the O,O,O-trialkyl phosphorothioates were effective in protecting rats treated with O,O-dimethyl S-methyl and S-ethyl phosphorothioates. O,O-Dimethyl and O,O-diethyl S-i-propyl phosphorothioates also were examined for in vitro and in vivo inhibition of rat plasma, red blood cell, and brain cholinesterase. Overall, the results indicated that two different mechanisms, cholinergic and noncholinergic, are involved in intoxication by the O,O,S-trialkyl phosphorothioates.

Animals↗
PubMed1985

Mutagenic and cell transformation activities of representative phosphorothioate esters in vitro.

Five alkyl and five aryl phosphorothioates are ranked relative to parathion in effectiveness as base-pair mutagens in the Ames mutagenic assay. Three in each series were mutagenic. Two commercial insecticidal phosphates, included for comparison, were mutagenic. The mutagenic phosphorothioates contained a strong electron-withdrawing and/or a good leaving group, together with two other groups small enough to permit nucleophilic attack by a biomacromolecule on the electrophilic phosphorus atom. All but one of the phosphorothioates [i.e., O,O,O-tris(2,2,2-trifluoro)ethyl phosphorothioate, VI] required metabolic activation for mutagenicity to be manifested; hence most of the phosphorothioates per se evidently are not ordinarily sufficiently electrophilic to be mutagenic but must instead be transformed to more electrophilic oxygen-containing products. In evaluation for cell-transformation properties, methyl parathion was inactive, in contrast to VI. The phosphorothioates that were novel were synthesized by formation of the phosphite from the appropriate alcohol or phenol, followed by reaction of the phosphite with sulfur.

Animals↗
PubMed2000

Evidence of enhanced iron excretion during systemic phosphorothioate oligodeoxynucleotide treatment.

BACKGROUND: Phosphorothioate oligonucleotides, in general, possess properties that could be utilized in the development of therapeutic heavy metal chelators. METHODS: Iron excretion was measured in 16 patients participating in studies to test the safety of OL(1)p53, a 20-mer phosphorothioate oligonucleotide complementary to p53 mRNA. Patients were given OL(1)p53 at doses of 0.05 to 0.25 mg/kg/h for 10 days by continuous intravenous infusion. Urine was collected during the study and analyzed for iron, copper, cadmium, and zinc. RESULTS: We found that phosphorothioate oligonucleotides have a high affinity for iron as well as several other clinically relevant toxic metals. Analysis of patient urine following administration of OL(1)p53 reveals a 7.5-fold increase in iron excretion at low doses (0.05 mg/kg/h). CONCLUSIONS: Phosphorothioate oligonucleotides may have therapeutic potential as heavy metal chelators. Low doses of phosphorothioate oligonucleotide facilitated the excretion of iron. Renal clearance of iron-phosphorothioate oligonucleotide complexes most likely involves secretion into proximal tubules.

Cadmium↗