Diphenylmethyl selenocyanate attenuates malachite green induced oxidative injury through antioxidation & inhibition of DNA damage in mice.

BACKGROUND & OBJECTIVES: Malachite green (MG), an environmentally hazardous material, is used as a non permitted food colouring agent, especially in India. Selenium (Se) is an essential nutritional trace element required for animals and humans to guard against oxidative stress induced by xenobiotic compounds of diverse nature. In the present study, the role of the selenium compound diphenylmethyl selenocyanate (DMSE) was assessed on the oxidative stress (OS) induced by a food colouring agent, malachite green (MG) in vivo in mice. METHODS: Swiss albino mice (Mus musculus) were intraperitoneally injected with MG at a standardized dose of 100 μg/ mouse for 30 days. DMSE was given orally at an optimum dose of 3 mg/kg b.w. in pre (15 days) and concomitant treatment schedule throughout the experimental period. The parameters viz. ALT, AST, LPO, GSH, GST, SOD, CAT, GPx, TrxR, CA, MN, MI and DNA damage have been evaluated. RESULTS: The DMSE showed its potential to protect against MG induced hepatotoxicity by controlling the serum alanine aminotransferase and aspartate amino transferase (ALT and AST) levels and also ameliorated oxidative stress by modulating hepatic lipid peroxidation and different detoxifying and antioxidative enzymes such as glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and also the selenoenzymes such as glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) and reduced glutathione level which in turn reduced DNA damage. INTERPRETATION & CONCLUSIONS: The organo-selenium compound DMSE showed significant protection against MG induced heptotoxicity and DNA damage in murine model. Better protection was observed in pretreatment group than in the concomitant group. Further studies need to be done to understand the mechanism of action

Design and synthesis of coumarin-based organoselenium as a new hit for myeloprotection and synergistic therapeutic efficacy in adjuvant therapy

Abstract A newly designed organoselenium compound, methyl substituted umbelliferone selenocyanate (MUS), was synthesized as a primary hit against the myelotoxic activity of carboplatin. MUS was administered at 6 mg/kg b.wt, p.o. in concomitant and pretreatment schedules with carboplatin (12 mg/kg b.wt, i.p. for 10 days) in female Swiss albino mouse. MUS treatment reduced (P < 0.001) the percentage of chromosomal aberrations, micronuclei formation, DNA damage and apoptosis in murine bone marrow cells and also enhanced (P < 0.001) the bone marrow cell proliferation of the carboplatin-treated mice. These activities cumulatively restored the viable bone marrow cell count towards normalcy. Myeloprotection by MUS was achieved, in part, due to a significant reduction in the ROS/RNS formation and restoration of glutathione redox pool. Additionally, MUS synergistically enhanced the cytotoxicity of carboplatin against two human cancer cell lines (MCF-7 and Colo-205). Furthermore, MUS can effectively potentiate the antitumour activity of carboplatin against two murine cancers (Dalton’s Lymphoma and Sarcoma-180) in vivo. These preclinical findings clearly indicate that MUS can improve the therapeutic index of carboplatin and ensures more effective therapeutic strategy against cancer for clinical development

Enhancing the Efficacy of Ara‑C through Conjugation with PAMAM Dendrimer and Linear PEG: A Comparative Study

1β-d-Arabinofuranosylcytosine (Cytarabine, Ara-C) is a key drug in the treatment of acute myeloid leukemia. Ara-C has a number of limitations such as a rapid deactivation by cytidine deaminase leading to the formation of a biologically inactive metabolite, Ara-U (1β-d-arabinofuranosyluracil), a low lipophilicity, and fast clearance from the body. To address these problems, we developed a conjugate in which hydroxyl-terminated PAMAM dendrimer, G4-OH [“D”] and PEG were used as carriers for the drug (Ara-C). The conjugates were synthesized using an efficient multistep protection/deprotection method resulting in the formation of a covalent bond between the primary hydroxyl group of Ara-C and dendrimer/PEG. The structure, physicochemical properties, and drug release kinetics were characterized extensively. ¹H NMR and MALDI-TOF mass spectrometry suggested covalent attachment of 10 Ara-C molecules to the dendrimer. The release profile of Ara-C in human plasma and in PBS buffer (pH 7.4) showed that the conjugates released the drug over 14 days in PBS, with the release sped up in plasma. In PBS, while most of the drug is released from PEG-Ara-C, the dendrimer continues to release the drug in a sustained fashion. The results also suggested that the formation of the inactive form of Ara-C (Ara-U) was delayed upon conjugation of Ara-C to the polymers. The inhibition of cancer growth by the dendrimer-Ara-C and PEG-Ara-C conjugates was evaluated in A549 human adenocarcinoma epithelial cells. Both dendrimer- and PEG-Ara-C conjugates were 4-fold more effective in inhibition of A549 cells compared to free Ara-C after 72 h of treatment

Rational incorporation of selenium into temozolomide elicits superior antitumor activity associated with both apoptotic and autophagic cell death.

BACKGROUND: The DNA alkylating agent temozolomide (TMZ) is widely used in the treatment of human malignancies such as glioma and melanoma. On the basis of previous structure-activity studies, we recently synthesized a new TMZ selenium analog by rationally introducing an N-ethylselenocyanate extension to the amide functionality in TMZ structure. PRINCIPAL FINDINGS: This TMZ-Se analog showed a superior cytotoxicity to TMZ in human glioma and melanoma cells and a more potent tumor-inhibiting activity than TMZ in mouse glioma and melanoma xenograft model. TMZ-Se was also effective against a TMZ-resistant glioma cell line. To explore the mechanism underlying the superior antitumor activity of TMZ-Se, we compared the effects of TMZ and TMZ-Se on apoptosis and autophagy. Apoptosis was significantly increased in tumor cells treated with TMZ-Se in comparison to those treated with TMZ. TMZ-Se also triggered greater autophagic response, as compared with TMZ, and suppressing autophagy partly rescued cell death induced by TMZ-Se, indicating that TMZ-Se-triggered autophagy contributed to cell death. Although mRNA level of the key autophagy gene, Beclin 1, was increased, Beclin 1 protein was down-regulated in the cells treated with TMZ-Se. The decrease in Beclin 1 following TMZ-Se treatment were rescued by the calpain inhibitors and the calpain-mediated degradation of Beclin1 had no effect on autophagy but promoted apoptosis in cells treated with TMZ-Se. CONCLUSIONS: Our study indicates that incorporation of Se into TMZ can render greater potency to this chemotherapeutic drug

TMZ-Se triggers a greater autophagic response than TMZ, and inhibition of autophagy decreases the efficacy of TMZ-Se against glioma cells.

<p>(<b>A</b>) <i>Left panels</i>: LN229 and T98G cells were treated with TMZ or TMZ-Se for 48 h, and the level of LC3 was measured by Western blot analysis. Tubulin was used as a loading control. <i>Right panels</i>: LN229 and T98G cells were treated with TMZ-Se for 48 h in the presence or absence of bafilomycinA1, and the level of LC3 was measured by Western blot analysis. Tubulin was used as a loading control. (<b>B</b>) LN229 and T98G cells were transfected with a GFP-LC3 plasmid, followed by treatment with TMZ-Se for 48h. At the end of treatment, the cells were observed under fluorescence microscope. (<b>C</b>) T98G cells treated with TMZ-Se or vehicle were harvested by trypsinization, fixed and embedded in spur resin. Ninety nm thin sections were cut and examined at 80 Kv with a JEOL 1200EX transmission electron microscope. (<b>D</b>) LN229 and T98G cells were treated with TMZ-Se for 48h in the absence or presence of 3-MA or bafilomycinA1, and cell viability was measured by MTT assay. (<b>E</b>) LN229 and T98G cells were transfected with an Atg5-targeted siRNA, and then treated with TMZ-Se for 48h. Cell viability was measured by MTT assay. *<i>p</i> < 0.05; **<i>p</i> < 0.01.</p

Effects of TMZ-Se and TMZ on tumor growth in mouse glioma and melanoma xenograft models.

<p>(<b>A and B</b>) The human glioma cells LN229 (1×10⁵ cells in 15 µl of DMEM medium) were injected into the brains of 6-week-old male BALB/c nude mice at 4 mm depth under anesthesia with chloralic hydras (4%, 2ml/kg, ip). Three days after tumor cell implantation, mice were randomly divided into three groups (15 mice/group). Treatments were begun on day 4. TMZ-SE (15 mg/kg), TMZ (15 mg/kg) or vehicle (10% DMSO in saline) was given p.o. daily for 2 weeks. (<b>A</b>) At day 7 and day 21 after tumor cell implantation, the mice were euthanized, and the brains were fixed in 10% buffered formalin, embedded in paraffin, and then stained with hematoxillin-eosin (H&E). The images shown are the representative of 5 mice from each group; (<b>B</b>) The kaplan-Meier survival curves, n = 10; (<b>C</b>) Nude mice (swiss^nu/nu) were inoculated s.c. with UACC903 human melanoma cells (1×10⁶ cells/100 µl/mouse). When the tumors reached 50∼100 mm³ in volume, TMZ or TMZ-Se (15 mg/kg) was administered i.p. on days 1, 3, 5, 7 and 9. Tumor sizes and body weight of the animals were measured every other day. The differences between treatments were analyzed using a two-sample <i>t</i>-test. The survival curves of the tumor - bearing mice subjected to different treatments were estimated using Kaplan-Meier method and compared by log-rank statistic analysis.</p

TMZ-Se is more apoptogenic than TMZ in tumor cells.

<p>(<b>A</b>) LN229 and T98G cells were treated with 100 µM or 200 µM of TMZ or TMZ-Se for 48 h, and apoptosis was examined by flow cytometric analysis of Annexin V and 7-AAD staining. (<b>B</b>) LN229 and T98G cells were treated with TMZ or TMZ-Se for 48h, and the levels of caspse-9, caspase-3, PARP and survivin were measured by Western blot analysis. Tubulin was used as a loading control. (<b>C</b>) LN229 and T98G cells were treated with TMZ-Se for 48h in the absence or presence of Z-VAD, and cell viability was measured by MTT assay. (<b>D</b>) 1205LU and UACC cells were treated with TMZ or TMZ-Se for 48h, and the levels of PARP and survivin were measured by Western blot. Tubulin was used as a loading control. *<i>p</i> < 0.05; **<i>p</i> < 0.01.</p

Chemical structures of TMZ-Se and TMZ.

<p>Chemical structures of TMZ-Se and TMZ.</p