Thiophosphate Compound Research Articles

Protective effect of amifostine on busulfan induced DNA damage in human hepatoma cells

Busulfan is one of the most effective chemotherapeutic agents used for the treatment of chronic myeloid leukemia. However, as a bifunctional alkylating agent, during clinical use several side effects may occur. In addition, several in vivo and in vitro studies of busulfan have shown a range of genotoxic effects including DNA strand break and inhibition of DNA synthesis. Amifostine, an organic thiophosphate compound, has been shown to exert an important cyto-protective effect in many tissues. The aim of this study was to explore whether amifostine protects against busulfan-induced genotoxicity in HepG2 cell line. Our results showed that amifostine reduced the genotoxic effects of busulfan significantly in both type of experiment conditions, as measured via comet assay. Furthermore, amifostine decreased the intracellular ROS generation induced by busulfan and also increased the intracellular GSH levels in HepG2 cells. Altogether, our results suggest a protective action of amifostine against busulfan cytotoxicity and genotoxicity via various pathways. The most protective effect was observed with amifostine when it was administrated 24 h before busulfan treatment.

Prediction of a new SelD‐like family that may participate in sulfur metabolism in hyperthermophilic sulfur‐reducing archaea

Selenium (Se) and sulfur (S) are closely related elements that exhibit similar chemical properties. Some genes related to S metabolism are also involved in Se utilization in many organisms. However, the evolutionary relationship between the two utilization traits is unclear. In this study, we conducted a comparative analysis of the selenophosphate synthetase (SelD) family, a key protein for all known Se utilization traits, in all sequenced archaea. Our search showed a very limited distribution of SelD and Se utilization in this kingdom. Interestingly, a SelD‐like protein was detected in two orders of Crenarchaeota: Sulfolobales and Thermoproteales. Genomic and phylogenetic analyses revealed that SelD‐like protein may share a common ancestor with SelD and might be involved in S metabolism in these S‐reducing organisms. Further genome‐wide analysis of patterns of genes occurrence in different thermoproteales suggested that several genes, including SirA‐like, Prx‐like and adenylylsulfate reductase, were strongly related to the SelD‐like protein. Finally, we proposed a simple model wherein the SelD‐like protein may play an important role in the biosynthesis of certain thiophosphate compound. Our data suggest novel genes involved in S metabolism in hyperthermophilic S‐reducing archaea, and may provide a new window for understanding the complex relationship between Se and S metabolism in archaea.

Infrared, Raman and resonance Raman spectra of the solid nickel(II) thiophosphate compound (PPh4)3 [(NiPS4)3] and force constants in the trinickel [Ni3P3S12]3− cyclic anion

The UV–visible (350–900 nm), infrared and Raman (30–800 cm−1) spectra of a new transition metal thiophosphate solid compound, (PPh4)3 [(NiPS4)3], were analyzed using powder samples. Electronic transitions of the 1F2 1A1 type originating in the (PS4)3− groups were detected from visible absorbance measurements in the 440–520 nm range and most of the expected infrared and Raman vibrational modes of the trimetallic ring anion [Ni3P3S12]3− were observed in the 600–30 cm−1 region. Also, resonance Raman spectra were recorded using exciting radiation of several wavelengths in the 680–450 nm range and the Raman excitation profiles of several fundamentals were established: they all peak near 488 nm and exhibit the strongest enhancements for totally symmetric and non-totally symmetric stretching and bending modes of (NiS4) groups. It is therefore concluded that several ligand to metal charge-transfer electronic transitions are overlapped and involved in vibronic coupling mechanisms. Furthermore, the vibrational assignments were checked by a valence force field calculation for an isolated [Ni3P3S12]3− anion of C3v symmetry. The potential energy distributions and mean squared vibrational amplitudes revealed strong ν(Ni–S) and δ(S–P–S) couplings and relatively high ν(Ni–S) stretching modes at near 310 cm−1. Compared with results in the one-dimensional KNiPS4 compound containing infinite anionic chains [NiPS4]−, one notes a force constant increase on the P—S exocyclic (µ1) bonds, no change on the bridged (µ2 and µ3) P—S bonds and a slight increase in the Ni–S stretching force constants varying from 75 to 85 N m−1 in accordance with a localized ligand to metal charge-transfer mechanism. Hence a comparison of the induced Raman scattering processes in the (PPh4)3 [(NiPS4)3] and KNiPS4 solid compounds shows that the ligand to metal charge transfers and the crystal field effects have a strong influence on the vibrational properties in these thiophosphate compounds. Copyright © 1999 John Wiley & Sons, Ltd.

Infrared, Raman and resonance Raman spectra of the solid nickel(II) thiophosphate compound (PPh4)3 [(NiPS4)3] and force constants in the trinickel [Ni3P3S12]3 cyclic anion

Infrared, Raman and resonance Raman spectra of the solid nickel(II) thiophosphate compound (PPh4)3 [(NiPS4)3] and force constants in the trinickel [Ni3P3S12]3 cyclic anion

Infrared, Raman and resonance Raman spectra and lattice dynamics calculations of the solid potassium(I) palladium(II) thiophosphate compound KPdPS4

The UV–Visible (350–900 nm), infrared and Raman (30–800 cm−1) spectra of a new transition metal thiophosphate solid compound, KPdPS4, were analyzed using powder samples and single-crystal platelets. From polarized absorbance measurements, the main electronic transitions of the 1F2 ← 1A1 type due to the (PS4)3− groups are localized in the 400–520 nm range and all the expected infrared vibrational modes were observed in the 600–30 cm−1 region; various polarized Raman measurements were also performed. The vibrational assignments were then checked by complete valence force field lattice dynamics calculations in the different symmetry blocks of the tetragonal crystal structure (D4h14). Potential energy distributions and mean squared vibrational amplitude calculations revealed strong ν(Pd–S) and δ(S–P–S) couplings in the one-dimensional inorganic polymer anionic 1∞[PdPS]4]− chains and remarkably high ν)Pd–S) stretching modes near 350 cm−1. Compared with results for the analogous Ni(II) compound, there was a significant increase in the M– S force constants, varying from 75 N m−1 (Ni– S) to 90 N m−1 (Pd– S) in accordance with the Pauling electronegativity scale. Furthermore, various resonance Raman spectra of micrometer-sized samples were recorded using a confocal microscope instrument in order to characterize not only the existence of chains having a distribution of length but also some Raman impurity bands coming from the dithiophosphate compound, K4Pd(PS4)2. Also, resonance Raman spectra of powder samples were recorded using several exciting radiation wavelengths over the range 800–500 nm in order to probe the nature of the low-energy electronic transition at 658 nm; the Raman excitation profiles of several fundamentals were thus established and they demonstrate that both totally symmetric and non-totally symmetric stretching and bending modes of the PS4 and PdS4 groups are markedly enhanced. We therefore conclude that several ligand to metal charge-transfer electronic transitions are overlapped and involved in vibronic coupling mechanisms with higher energy bands. Finally, a comparison of the induced Raman scattering processes in the Cu3PS4, KNiPS4 and KPdPS4 solid compounds showed that the ligand to metal charge transfers and the crystal field effects have a strong influence on the optical and vibronic properties of these thiophosphate compounds. Copyright © 1999 John Wiley & Sons, Ltd.

Infrared, Raman and resonance Raman spectra and lattice dynamics calculations of the solid potassium(I) palladium(II) thiophosphate compound KPdPS4

Infrared, Raman and resonance Raman spectra and lattice dynamics calculations of the solid potassium(I) palladium(II) thiophosphate compound KPdPS4

Cardioprotection of rat heart myocytes with amifostine (Ethyol ®) and its free thiol, WR-1065, in vitro

Cultured neonatal rat heart myocytes form a synchronously-contracting cell syncytium from one to two days after isolation, plating on plastic and incubation at 37 degrees C. On day 3 after plating, myocytes were exposed to the anthracycline doxorubicin, 0.1-10 micrograms/ml, for 1 h with or without a 15-min pretreatment with the thiophosphate compound amifostine (WR-2721, Ethyol) or its dephosphorylated metabolite, WR-1065. The concentration of each WR-compound was limited to 2 micrograms/ml or 10% of the maximal achievable plasma concentration of amifostine after an intravenous dose of 740 mg/m2. Both amifostine and the free thiol significantly reduced doxorubicin-induced heart-cell toxicity, measured by adenosine triphosphate content normalised to total cellular protein. A concurrent 1-h exposure to these compounds and doxorubicin was also cardioprotective, but neither compound was effective when administered after doxorubicin. Although both amifostine and WR-1065 were approximately equipotent in preventing doxorubicin-induced cardiotoxicity, only amifostine significantly increased glutathione levels in the myocytes. These results complement prior in vitro and in vivo studies in rodents showing cardioprotectant activity for amifostine and its free thiol, WR-1065, when administered prior to doxurubicin.

The need for cytoprotection

The toxicity associated with chemotherapy is significant and dose limiting. Multiple organ systems can be affected, with both acute and chronic side effects producing adverse effects. The concept of cytoprotection, or the selective protection of normal tissues is a strategy now being investigated in preclinical and clinical models. Systemic approaches have included the use of compounds such as sodium thiosulphate, diethyldithiocarbamate and amifostine. The most promising results have been obtained with the organic thiophosphate compound amifostine (Ethyol, WR-2721).

Infrared, Raman, resonance Raman spectra and lattice dynamics calculations of the solid potassium(I) nickel(II) thiophosphate compound, KNiPS4

Abstract The UV-visible (350–850 nm), infrared and Raman (20–700 cm−1) spectra of a new KNiPS4 solid compound have been analyzed using powder samples and crystalline platelets. From polarization measurements, the main electronic transition of 1F2←1A1 type due to the PS43− thiophosphate groups are localized in the 360–570 nm range and vibrational assignments for most of the fundamental modes are proposed. These assignments were checked by complete valence force field lattice dynamics calculations in the various symmetry blocks of the tetragonal crystal structure (D4h14). Potential energy distributions as well as mean squared vibrational amplitude calculations have shown strong ν(NiS) and σ(SPS) couplings in the (NiPS4)− structural chains and remarkably high ν(NiS) infrared frequencies. Furthermore, the resonance Raman spectra of single crystals and powder samples were recorded over a wide range (647.1-476.5 nm) of excitatiob wavelengths. This allowed to probe the nature of the broad electronic transition of the complex centered around 510 nm and responsible for KNiPS4 brown color. The Raman excitation profiles of several fundamentals and combination bands were thus established. Under resonance conditions, various crystalline components of A1g, B1g and B2g symmetry for the ν4(F2) or ν2(E) deformation modes of the PS43− groups are enhanced. No overtone progressions involving totally symmetric modes were observed but anomalously intense high-order combination bands were detected. It is thus concluded that adiabatic as well as non-adiabatic interactions must play a great role in the vibronically induced Raman scattering processes. Reasons for this peculiar behavior are discussed in relation to the X-ray crystal structure of the KNiPS4 compound. All the experimental results imply the presence of substantial site and factor group effects on the optical and vibronic properties of the thiophosphate anions.

Topical application of WR-2721 to prevent radiation-induced proctosigmoiditis. A phase I/II trial

Patients undergoing x-ray therapy to the pelvis have intestinal symptoms proportional to the volume treated and the dose delivered. WR-2721, S-2 (3-aminopropylaminoethyl) phosphorothioic acid, is an organic thiophosphate compound that selectively protects normal tissues against radiation effects. A Phase I/II study was done to test the ability of topical application of WR-2721 to protect the mucosa of the rectosigmoid from radiation damage. Thirty-one patients were enrolled in this study, of which, seven were control subjects. Twenty-four patients received WR-2721 daily, in enema form, 45 minutes before treatment. The patients were assigned by groups of three to receive increasing doses of WR-2721 beginning with 100 mg/enema to 450 mg/enema. Rectal mucosal biopsies were obtained within the treated field before, during, and at the end of therapy. The degree of damage to the rectal mucosa was scored on the basis of a 0 to 4 scale (with 0, least damage to 4, most damage) as determined by the percentage of damaged mucosal crypt glands. The patients' symptoms were recorded once a week during the entire course of therapy. The biopsy scores of the control group were slightly higher than those of the treatment groups; however, this difference did not appear to be significant. In the treated groups, there was a slight decrease in the biopsy scores with increasing doses of WR-2721, but this trend was not sustained. There were no differences among any of the groups in the symptoms experienced during the course of therapy. This study showed that WR-2721 could be administered safely in enema form in doses ranging from 100 to 450 mg/enema, but this drug did not protect the rectosigmoid mucosa from radiation damage at the doses administered.

WR-2721 and high-dose cisplatin: an active combination in the treatment of metastatic melanoma.

Cisplatin, alone or in combination with other chemotherapeutic agents, is relatively inactive against metastatic melanoma. Prior trials have demonstrated partial response (PR) rates of less than 10% with cisplatin alone. WR-2721 is an organic thiophosphate compound, which in the animal model, selectively protects normal tissues against the toxicity of cisplatin chemotherapy. During the course of a phase I trial of WR-2721 and cisplatin, objective PRs were noted in patients with far advanced metastatic melanoma. These observations led us to perform a phase II trial of WR-2721 and cisplatin. Thirty-six patients received 128 courses of WR-2721 before cisplatin (60 to 150 mg/m2). All patients had progressive disease before treatment. Objective PRs were observed in 19 of 36 evaluable patients (53%). Three additional patients had minor responses (MRs). PRs occurred in 53% of patients with prior chemotherapy (ten of 19). Sites of responding metastases were subcutaneous disease (15 of 19 patients), lymph nodes (16 of 21 patients), lung (four of ten patients), and liver (eight of 17 patients). The median duration of response was 4 months, with a mean of 4.5 months (range, 1 to 8 months). Transient nephrotoxicity was observed in less than 5% of courses. In all cases, renal function returned to normal within 1 to 2 weeks. Hematologic toxicity was mild and infrequent. Nine patients developed peripheral neuropathy following a median cisplatin dose of 670 mg/m2. Twenty patients experienced mild clinical hearing loss. These data suggest that WR-2721 may potentiate the antitumor activity of cisplatin in metastatic melanoma.

Intracolonic WR 2721 protection of the rat colon from acute radiation injury

The radioprotective thiophosphate compound WR 2721, when given intraperitoneally, has been shown to effectively protect normal murine tissues, but not tumors, from radiation injury. Intravenous administration in humans has produced limiting nausea and vomiting at protective doses. The accessibility of the colon, coupled with the frequency of acute radiation injury to the rectum during pelvic irradiation, stimulated us to determine if WR 2721 was radioprotective when administered intracolonically. Double-blind histologic evaluation of colons from irradiated rats treated with intracolonic WR 2721 demonstrated a radioprotective effect with a dose modifying factor of 1.8 when compared with controls. A contact time of 30–60 min was optimal as was a WR 2721 dose of at least 15 mg. No systemic absorption was found. These data demonstrate that WR 2721 exerts its radioprotective effect without the coincident development of secondary tissue hypoxia and provide rationale for a clinical trial in humans.

Phase I Controlled trials of WR-2721 and cyclophosphamide

WR-2721 is an organic thiophosphate compound which in the animal model selectively protects against the hematologic toxicity of cyclophosphamide by factors of 1.5 to 2.0. Controlled Phase I trials of WR-2721 and cyclophosphamide were initiated to determine if WR-2721 protected against cyclophosphamide's hematologic toxicity. Fifteen patients received WR-2721 (450–1100 mg/m 2) prior to cyclophosphamide (1200–1800 mg/m 2) and were subsequently retreated 4 weeks later with the same cyclophosphamide dose alone. With WR-2721 pretreatment, 11 15 (73%) patients had improved WBC counts. The mean WBC increased from 1800/mm 3 on cyclophosphamide alone to 2700/mm 3 with WR-2721 + cyclophosphamide ( p = 0.008). In 11 patients who had nadir differential counts performed, 7 64% demonstrated improved nadir granulocyte counts with WR-2721. The mean granulocyte count increased from 765/mm 3 on cyclophosphamide to 1274/mm 3 with WR-2721 + cyclophosphamide ( p = 0.05). In the second trial, 25 patients received the reverse sequence: an initial dose of cyclophosphamide (1200–1800 mg/m 2) alone, followed 4 weeks later by WR-2721 (450–1100 mg/m2) prior to the same dose of cyclophosphamide. With WR-2721 pretreatment, 12 25 (48%) patients had improved nadir WBC counts. The mean WBC increased from 1550/mm 3 on cyclophosphamide alone to 1850/mm 3 with WR-2721 + cyclophosphamide ( p = 0.02), while the nadir granulocyte count increased from 449/mm 3 to 844/mm 3 ( p = 0.001). No patient developed microscopic or gross hematuria or inappropriate antidiuretic hormone secretion. One patient developed mild thrombocytopenia. These data suggest that WR-2721 provides significant protection against cyclophosphamide-induced granulocytopenia, but the dose modification factors and degree of clinical benefit remain to be established. The current recommended WR-2721 dose for Phase II trials is 740 mg/m 2 administered over 15 minutes.

Rapid Screening of Radioprotective Drugs in Vivo

The traditional test for radioprotection, a measurement of the ${\rm LD}_{50/30}$ , requires a 1-mo wait between treatment and result. An alternative method is proposed which requires only a 3-day wait. It requires fewer mice but more man-hours than ${\rm LD}_{50/30}$ measurement. The frequency of micronuclei which result from chromosomal aberrations is the criterion of damage. It is shown that a thiophosphate compound S-2-(3-aminopropylamino) ethylphosphorothioic acid (WR 2721) produced a similar protection measured in this way as had been found by the traditional method.

Differential radioprotection of euoxic and hypoxic mouse mammary tumors by a thiophosphate compound.

The radioprotective drug S-2-(3-aminopropylamino) ethyl phosphorothioate (WR2721) was evaluated in the EMT-6 mouse mammary tumor. Under euoxic conditions (DMF approximately 2), the drug protected the oxygenated portion of the tumor but not chronically hypoxic cells. Acutely hypoxic cells were protected to a slight degree. Since WR2721 has been shown to protect normal tissues with a DMF of 2–3, it is likely that decreased protection of anoxic tumor cells will be clinically useful.