3,3'-Diselenodipropionic acid (DSePA) induces reductive stress in A549 cells triggering p53-independent apoptosis: A novel mechanism for diselenides.

The aim of present study was to investigate the anticancer mechanisms of 3,3'-diselenodipropionic acid (DSePA), a redox-active organodiselenide in human lung cancer cells. DSePA elicited a significant concentration and time-dependent cytotoxicity in human lung cancer cell line A549 than in normal WI38 cells. The cytotoxic effect of DSePA was preceded by an acute decrease in the level of basal reactive oxygen species (ROS) and a concurrent increase in levels of reducing equivalents (like GSH/GSSG and NADH/NAD) within cells. Further, a series of experiments were performed to measure the markers of intrinsic (Bax, cytochrome c and caspase-9), extrinsic (TNFR, FADR and caspase-8) and endoplasmic reticulum (ER) stress (protein ubiquitylation, calcium flux, Bip, CHOP and caspase-12) pathways in DSePA treated cells. DSePA treatment significantly increased the levels of all the above markers. Moreover, DSePA did not alter the expression and phosphorylation (Ser15) of p53 but caused a significant damage to mitochondria. Pharmacological modulation of GSH level by BSO and NAC in DSePA treated cells led to partial abrogation and augmentation of cell kill respectively. This established the role of reductive stress as a trigger for the apoptosis induced by DSePA treatment. Finally, in vitro anticancer activity of DSePA was also corroborated by its in vivo efficacy of suppressing the growth of A549 derived xenograft tumor in SCID mice. In conclusion, above results suggest that DSePA induces apoptosis in a p53 independent manner by involving extrinsic and intrinsic pathways together with ER stress which can an interesting strategy for lung cancer therapy.

Development of surface functionalized hydroxyapatite nanoparticles for enhanced specificity towards tumor cells.

Nanoparticles coupled with targeting moieties have attracted a great deal of attention for cancer therapy since they can facilitate site-specific delivery of drug and significantly limit the side effects of systemic chemotherapy. In this study, our aim is to develop surface functionalized hydroxyapatite nanoparticles, which could provide binding sites for a cancer cell targeting ligand, folic acid (FA) as well as an anticancer drug, doxorubicin hydrochloride (DOX). In order to attain dual functionalities, hydroxyapatite nanoparticles were functionalized with gelatin molecules. Gelatin, being a protein has both carboxyl and amine moieties, which makes it suitable for binding of DOX and FA. FA was chemically conjugated to the nanoparticles through an EDCNHS coupling reaction. The formation of single-phase hydroxyapatite nanostructure was ascertained by X-ray diffraction studies and the presence of organic moieties on the surface of nanoparticles was evident from Fourier transform infrared spectroscopy, thermogravimetric analysis and U.V.-visible spectroscopy. The FA-conjugated nanoparticles (FA-Gel-HANPs) showed high affinity towards DOX and pH-responsive sustained release of drug with higher release rate under acidic pH conditions, desired for cancer therapy. The FA-Gel-HANPs showed negligible cytotoxicity towards different cell lines (HepG2, WEHI-164, KB, WI-26 VA4 and WRL-68). However, DOX loaded nanoparticles (DOX-FA-Gel-HANPs) exhibited significant toxicity towards these cells, which was however highest in folate receptor (FR)-overexpressing, KB cells. These results were correlated with enhanced cellular uptake of DOX-FA-Gel-HANPs in KB cells in comparison to FR-deficient, WRL-68 cells studied by confocal laser scanning microscopy and flow cytometry. Moreover, cell cycle analysis in KB cells, showed higher sub-G1 population, indicating apoptosis as one of the cell death mechanisms. Overall, this study suggests that DOX-FA-Gel-HANPs could serve as a promising tumor-targeted drug delivery system.

Oral administration of 3,3'-diselenodipropionic acid prevents thoracic radiation induced pneumonitis in mice by suppressing NF-kB/IL-17/G-CSF/neutrophil axis.

The incidence of symptomatic radiation induced lung pneumonitis (RILP), a major dose limiting side effect of thoracic radiotherapy, is in the range of 15-40%. Therapeutic options for the prevention and treatment of RILP are limited. Hence there is a need for developing novel radioprotectors to prevent RILP which can be patient compliant. This study sought to evaluate the efficacy of oral 3,3'-diselenodipropionic acid (DSePA), a novel selenocystine derivative to prevent RILP. C3H/HeJ (pneumonitis responding) mice received a single dose of 18 Gy, whole thorax irradiation and a subset were treated with DSePA orally (2.5 mg/kg), three times per week beginning 2 h post irradiation and continued till 6 months. DSePA delayed onset of grade ≥ 2 RILP by 45 days compared to radiation control (~105 versus ~60 days). It also reversed the severity of pneumonitis in 3/10 radiation treated mice leading to significant improvement in asymptomatic survival compared to radiation control (~180 versus ~102 days). DSePA significantly (p < 0.05) reduced the radiation-mediated infiltration of polymorphonuclear neutrophils (PMN) and elevation in levels of cytokines such as IL1-ß, ICAM-1, E-selectin, IL-17 and TGF-ß in the bronchoalveolar lavage fluid. Moreover DSePA lowered PMN-induced oxidants, maintained glutathione peroxidase activity and suppressed NF-kB/IL-17/G-CSF/neutrophil axis in the lung of irradiated mice. Additionally, this compound did not protect A549 (lung cancer) derived xenograft tumor from radiation exposure in SCID mice. DSePA offers protection to normal lung against RILP without affecting radiation sensitivity of tumors. It has the potential to be developed as an oral agent for preventing RILP.

Interaction of a Model Hydrophobic Drug Dimethylcurcumin with Albumin Nanoparticles.

The aim of present study was to investigate the binding interactions of a model hydrophobic molecule, dimethylcurcumin (DMC) with nanoparticle form of bovine serum albumin (BSA) using fluorescence spectroscopy techniques. For this, BSA nanoparticles (size = 62.0 ± 3.5 nm, molecular weight = 11,243 ± 3445 kD) prepared by thermal denaturation method was mixed with DMC in solution and monitored for fluorescence emission of tryptophan (Trp) residue as well as DMC separately. The emission maximum of DMC in nanoparticles form exhibited more blue sift and quenched the excited state of tryptophan (Trp) by six fold higher than in the native form of BSA. By analyzing Trp fluorescence, the mean binding constant (K) estimated for the interaction of DMC with native and nanoparticles forms of BSA was 2.7 ± 0.4 × 104 M-1 and 1.5 ± 0.5 × 105 M-1 respectively. Together these results suggested that DMC experienced a more rigid environment in nanoparticles than in native form of BSA. Additionally the above determined K values were in agreement with those reported previously by absorption techniques. Further direct energy transfer was observed between Trp and DMC, using which the distance (r) calculated between them was 28.25 ± 0.27 Çº in BSA native. Similar analysis involving BSA nanoparticle and DMC revealed a distance of 24.25 ± 1.05 Çº between the hydrophobic core and the ligand. Finally interaction of DMC with BSA was validated through molecular docking studies, which indicated sub-domain IIA as the binding site of DMC. Thus it is concluded that intrinsic fluorescence of protein can be utilized to study the interaction of its different physical forms with any hydrophobic ligand.

pH sensitive surfactant-stabilized Fe3O4 magnetic nanocarriers for dual drug delivery.

Highly water-dispersible surfactant-stabilized Fe3O4 magnetic nanocarriers (SMNCs) were prepared by self-assembly of anionic surfactant, sodium dodecyl sulphate (SDS) on hydrophobic (oleic acid coated) nanoparticles and their biomedical applications were investigated. These nanocarriers have an average size of about 10nm and possess tunable surface charge properties. The formation of an organic coating of SDS was evident from infrared spectroscopy, dynamic light scattering, zeta-potential and thermogravimetric measurements. These nanocarriers were used for loading of both hydrophilic and hydrophobic anticancer agents such as doxorubicin hydrochloride (DOX) and curcumin (CUR), respectively. DOX was conjugated onto the surface of nanocarriers through electrostatic interaction, whereas CUR was encapsulated into the hydrophobic interlayer between oleic acid and SDS. The toxicity and cellular internalization of drug loaded nanocarriers were investigated against WEHI-164 cancer cell line. Specifically, the drug loading, pH sensitive drug release and cellular internalization studies suggested that these nanocarriers are suitable for dual drug delivery. Furthermore, they show good heating ability under AC magnetic field, thus can be used as effective heating source for hyperthermia treatment of cancer.

PEG coated vesicles from mixtures of Pluronic P123 and l-α-phosphatidylcholine: structure, rheology and curcumin encapsulation.

PEG coated vesicles are important vehicles for the passive targeting of anticancer drugs. With a view to prepare PEG decorated vesicles using co-assembly of block copolymers and lipids, here we investigated the microstructure of aggregates formed in mixtures comprising lipids (l-α-phosphatidylcholine) and block copolymers (Pluronic P123), in the polymer rich regime. DLS and SANS studies show that the structure of the aggregates can be tuned from micelles to rod-like micelles or vesicles by changing the lipid to polymer composition. Rheological studies on gels formed by mixtures of polymer and lipid suggest incorporation of the lipid into the polymer matrix. The encapsulation efficiencies of polymer incorporated liposomes for curcumin and doxorubicin hydrochloride (DOX) are evaluated at different drug to carrier ratios. The pH dependent sustained release of both the drugs from the PEGylated liposomes suggests their application in the development of cost effective formulations for anticancer drug delivery.

Tuning the binding, release and cytotoxicity of hydrophobic drug by Bovine Serum Albumin nanoparticles: Influence of particle size.

To elucidate the effect of particle size of albumin nanoparticles on cellular uptake of a hydrophobic drug, herein we report the release kinetics and cytotoxicity of nanoparticle bound dimethylcurcumin (DMC) in A549 tumor cells. The bovine serum albumin (BSA) nanoparticles were prepared by thermal denaturation and characterized by dynamic light scattering (DLS), zeta (ζ) -potential, circular dichroism (CD) and transmission electron microscope (TEM). The preparation conditions were optimized to obtain nanoparticles with mean hydrodynamic diameters 28.0nm (BSAnp1) and 52.0nm (BSAnp2) and corresponding ζ- potential value of∼-7.0 and -6.0mV, respectively. Interaction of DMC with BSA nanoparticles was investigated by UV-vis, fluorescence and CD spectroscopy. CD studies indicated significant changes in the secondary structure of BSA upon particle formation, as revealed by decrease in the helicity. The cellular uptake of DMC increased with increase in particle size and the toxicity of DMC loaded nanoparticles to A549 cells were found to be consistent with their cellular uptake. Between the two formulations studied, BSAnp2 provided enhanced cellular uptake and can be used as an effective delivery system for hydrophobic drugs like DMC.

Curcumin and Its Role in Chronic Diseases.

Curcumin, a yellow pigment from the spice turmeric, is used in Indian and Chinese medicine since ancient times for wide range of diseases. Extensive scientific research on this molecule performed over the last 3 to 4 decades has proved its potential as an important pharmacological agent. The antioxidant, anti-inflammatory, antimicrobial and chemopreventive activities of curcumin have been extended to explore this molecule against many chronic diseases with promising results. Further, its multitargeting ability and nontoxic nature to humans even up to 12 g/day have attracted scientists to explore this as an anticancer agent in the clinic, which is in different phases of trials. With much more scope to be investigated and understood, curcumin becomes one of the very few inexpensive botanical molecules with potent therapeutic abilities.

A selenocysteine derivative therapy affects radiation-induced pneumonitis in the mouse.

The mechanism leading to the radiation-induced lung response of pneumonitis is largely unknown. Here we investigated whether treatment with 3,3'-diselenodipropionic acid (DSePA), which reduces radiation-induced oxidative stress in acute response models, decreases the lung response to irradiation. Mice of the C3H/HeJ (alveolitis/pneumonitis-responding) strain received 18 Gy whole-thorax irradiation, and a subset of these mice was treated with DSePA (2 mg/kg) three times per week, beginning at 2 hours after radiation treatment, and continuing in the postirradiation period until death because of respiratory distress symptoms. DSePA treatment increased the postirradiation survival time of mice by an average of 32 days (P = 0.0002). Radiation-treated and DSePA-treated mice presented lower levels of lipid peroxidation and augmented glutathione peroxidase in the lungs, compared with those levels measured in mice receiving radiation only, when mice receiving radiation only were killed because of distress symptoms, whereas catalase and superoxide dismutase levels did not show consistent differences among treatment groups. DSePA treatment decreased pneumonitis and the numbers of mast cells, neutrophils, and lymphocytes in the lungs and bronchoalveolar lavage, respectively, of irradiated mice relative to mice exposed to radiation alone. DSePA treatment also decreased the radiation-induced increase in granulocyte colony-stimulating factor levels in the bronchoalveolar lavage and lung-tissue expression of intercellular adhesion molecule-1 and E-selectin, while increasing the expression of glutathione peroxidase-4. We conclude that DSePA treatment reduces radiation-induced pneumonitis in mice by delaying oxidative damage and the inflammatory cell influx.

Melanin, a promising radioprotector: mechanisms of actions in a mice model.

The radioprotective effect of extracellular melanin, a naturally occurring pigment, isolated from the fungus Gliocephalotrichum simplex was examined in BALB/C mice, and the probable mechanism of action was established. At an effective dose of 50mg/kg body weight, melanin exhibited both prophylactic and mitigative activities, increasing the 30-day survival of mice by 100% and 60%, respectively, after exposure to radiation (7Gy, whole body irradiation (WBI)). The protective activity of melanin was primarily due to inhibition of radiation-induced hematopoietic damages as evidenced by improvement in spleen parameters such as index, total cellularity, endogenous colony forming units, and maintenance of circulatory white blood cells and platelet counts. Melanin also reversed the radiation-induced decrease in ERK phosphorylation in splenic tissue, which may be the key feature in its radioprotective action. Additionally, our results indicated that the sustained activation of AKT, JNK and P38 proteins in splenic tissue of melanin pre-treated group may also play a secondary role. This was also supported by the fact that melanin could prevent apoptosis in splenic tissue by decreasing BAX/Bcl-XL ratio, and increasing the expressions of the proliferation markers (PCNA and Cyclin D1), compared to the radiation control group. Melanin also reduced the oxidative stress in hepatic tissue and abrogated immune imbalance by reducing the production of pro-inflammatory cytokines (IL6 and TNFα). In conclusion, our results confirmed that fungal melanin is a very effective radioprotector against WBI and the probable mechanisms of radioprotection are due to modulation in pro-survival (ERK) signaling, prevention of oxidative stress and immunomodulation.

Dimethoxycurcumin-induced cell death in human breast carcinoma MCF7 cells: evidence for pro-oxidant activity, mitochondrial dysfunction, and apoptosis.

The factors responsible for the induction of cell death by dimethoxycurcumin (Dimc), a synthetic analog of curcumin, were assessed in human breast carcinoma MCF7 cells. Initial cytotoxic studies with both curcumin and Dimc using MTT assay indicated their comparable effects. Further, the mechanism of action was explored in terms of oxidative stress, mitochondrial dysfunction, and modulation in the expression of proteins involved in cell cycle regulation and apoptosis. Dimc (5-50 µM) caused generation of reactive oxygen species, reduction in glutathione level, and induction of DNA damage. The mitochondrial dysfunction induced by Dimc was evidenced by the reduction in mitochondrial membrane potential and decrease in cellular energy status (ATP/ADP) monitored by HPLC analysis. The observed decrease in ATP was also supported by the significant suppression of different (α, ß, γ, and ε) subunits of ATP synthase. The cytotoxic effect of Dimc was further characterized in terms of induction of S-phase cell cycle arrest and apoptosis, and their relative contribution was found to vary with the treatment concentration of Dimc. The S-phase arrest and apoptosis could also be correlated with the changes in the expressions of cell cycle proteins like p53, p21, CDK4, and cyclin-D1 and apoptotic markers like Bax and Bcl-2. Overall, the results demonstrated that Dimc induced cell death in MCF7 cells through S-phase arrest and apoptosis.

Polyphenolic fraction of Pilea microphylla (L.) protects Chinese hamster lung fibroblasts against γ-radiation-induced cytotoxicity and genotoxicity.

Present study was designed to compare cytoprotective and antigenotoxic activity of the polyphenolic fraction of Pilea microphylla (PM1) with that of its active polyphenolic constituents against γ-radiation in V79 cells. PM1 was standardized with respect to the polyphenols present by RP-HPLC. It was evaluated for its free radical scavenging potential using Fenton reaction-induced DNA damage and lipid peroxidation. Further, PM1 was subjected against γ-radiation-induced cytotoxicity and genotoxicity in V79 cells. PM1 significantly reduced free radical-mediated calf thymus DNA damage and lipid peroxidation. Among the concentrations tested (12.5, 25 and 50 µg/ml) for radioprotection, PM1 at 25 µg/ml exhibited maximum protection. Further, when compared with constituent polyphenols viz., rutin, quercetin and chlorogenic acid (concentrations equivalent to that present in PM1-25 µg/ml), a combination of polyphenols was found most effective in preventing γ-radiation-induced cytotoxicity and genotoxicity. To conclude, radioprotection is possibly a synergistic effect of the phytochemicals present in the herbal extract, rather than any single component.

Antidiabetic, antihyperlipidemic and antioxidant effects of the flavonoid rich fraction of Pilea microphylla (L.) in high fat diet/streptozotocin-induced diabetes in mice.

The present study describes the antidiabetic effect of the flavonoid rich fraction of Pilea microphylla (PM1). HPLC characterization of PM1 revealed the presence of polyphenols viz., chlorogenic acid, rutin, luteolin-7-O-glucoside, isorhoifolin, apigenin-7-O-glucoside, and quercetin. PM1 inhibited dipeptidyl peptidase IV (DPP-IV) in vitro with an IC(50) of 520.4±15.4 µg/ml. PM1, at doses of 300, 600 and 900 mg/kg i.p., also produced dose-dependent mean percent reductions of 9.9, 30.6 and 41.0 in glucose excursion (AUC(0-120 min)) respectively in lean mice. However, even the highest dose of PM1 did not alter normoglycemic condition. PM1 at dose of 100 mg/kg/day, i.p. for 28 days produced significant (p<0.05) reduction in body weight, plasma glucose (PG), triglycerides (TG) and total cholesterol (TC) content in high-fat streptozotocin-induced diabetic mice. PM1 also improved oral glucose tolerance significantly (p<0.05) with mean percentage reduction of 48.0% in glucose excursion (AUC(0-120 min)) and significantly (p<0.05) enhanced the endogenous antioxidant status in mice liver compared to diabetic control. PM1 preserved islet architecture and prevented hypertrophy of hepatocytes as evident from the histopathology of pancreas and liver. PM1 did not show any detectable hematological toxicity at therapeutic doses. In conclusion, PM1 exhibits antidiabetic effect possibly by inhibiting DPP-IV and improving antioxidant levels in high fat diet/streptozotocin (HFD/STZ) diabetic mice.

Dimethoxycurcumin, a metabolically stable analogue of curcumin, exhibits anti-inflammatory activities in murine and human lymphocytes.

The aim of this study was to investigate whether dimethoxycurcumin (DiMC), a synthetic curcumin analogue having higher metabolic stability over curcumin, could exhibit anti-inflammatory activity in murine and human lymphocytes. Both curcumin and DiMC suppressed mitogen as well as antigen driven proliferation of murine splenic lymphocytes. Further, mitogen and antigen-stimulated cytokine (IL-2, IL-4, IL-6 and IFN-γ) secretion by T cells was also abrogated by curcumin and DiMC. Interestingly, curcumin and DiMC suppressed B cell proliferation induced by lipopolysaccharide. Curcumin and DiMC also inhibited Con A-induced activation of early and late T cell activation markers. They scavenged basal reactive oxygen species and depleted GSH levels in lymphocytes. The suppression of mitogen-induced T cell proliferation and cytokine secretion by curcumin and DiMC was significantly abrogated by thiol containing antioxidants suggesting a role for redox in their anti-inflammatory activity. Further, the possibility of curcumin and DiMC directly interacting with thiol-containing antioxidant GSH was monitored by changes in absorbance. Both curcumin and DiMC inhibited Con A induced activation of NF-κB and MAPK. More importantly, curcumin and DiMC inhibited phytohaemagglutinin induced proliferation and cytokine secretion by human peripheral blood mononuclear cells. To explore their therapeutic efficacy, they were added to lymphocytes post-Con A stimulation and we observed a significant suppression of IL-2, IL-6 and IFN-γ. The present study for the first time demonstrates the potent anti-inflammatory activity of DiMC. Further, DiMC could find application as an alternative to curcumin, which is currently used in several clinical studies, due to its superior bioavailability and comparable efficacy.

Anti-apoptotic, anti-inflammatory, and immunomodulatory activities of 3,3'-diselenodipropionic acid in mice exposed to whole body γ-radiation.

The present study was designed to evaluate the possible protective effects of 3,3'-diselenodipropionic acid (DSePA), a potent radioprotector, against oxidative organ damage induced by whole body γ-irradiation and explore its mechanistic effects. The mice were subjected to whole body γ-irradiation at 5 Gy for the detection of oxidative stress, apoptosis, and proliferation in the intestinal (jejunum) tissue and at 7 Gy for the examination of intestinal inflammation and immune imbalance. Groups of mice received intraperitoneal injections of DSePA (2 mg/kg/day) or vehicle (phosphate-buffered saline) for 5 consecutive days prior to irradiation. The whole body γ-irradiation of mice led to the induction of oxidative stress and apoptosis in the intestinal tissue, and pretreatment with DSePA significantly reduced both these parameters. It was also found to abrogate the radiation-induced intestinal inflammatory response and augment the proliferation of intestinal cells. Additionally, irradiation-induced polarization of Th1/Th2 immune balance toward the Th2-dominant direction and pretreatment with DSePA ameliorated this shift, which may be beneficial for the recovery from radiation injury. In conclusion, pretreatment with DSePA prevented radiation-induced oxidative damage in small intestine and the underlying mechanisms responsible for this could be attributed to inhibition of oxidative stress, apoptosis, and inflammation.

Synthesis, characterization and structures of 2-(3,5-dimethylpyrazol-1-yl)ethylseleno derivatives and their probable glutathione peroxidase (GPx) like activity.

A series of 2-(3,5-dimethylpyrazol-1-yl)ethylseleno derivatives has been synthesized. The glutathione peroxidase like catalytic activity of these compounds has been studied in a model system, in which reduction of hydrogen peroxide with dithiothreitol (DTT(red)), in the presence of an organoselenium compound was investigated by (1)H NMR spectroscopy. All these compounds exhibit GPx like catalytic activities and the catalytic reaction proceeds through a selenoxide intermediate, identified by (77)Se{(1)H} NMR spectroscopy.

Protective effects of selenocystine against γ-radiation-induced genotoxicity in Swiss albino mice.

Selenocystine (CysSeSeCys), a diselenide aminoacid exhibiting glutathione peroxidase-like activity and selective antitumor effects, was examined for in vivo antigenotoxic and antioxidant activity in Swiss albino mice after exposure to a sublethal dose (5 Gy) of γ-radiation. For this, CysSeSeCys was administered intraperitoneally (i.p.) to mice at a dosage of 0.5 mg/kg body weight for 5 consecutive days prior to whole-body γ-irradiation. When examined in the hepatic tissue, CysSeSeCys administration reduced the DNA damage at 30 min after radiation exposure by increasing the rate of DNA repair. Since antigenotoxic agents could alter the expression of genes involved in cell cycle arrest and DNA repair, the transcriptional changes in p53, p21 and GADD45α were monitored in the hepatic tissue by real-time PCR. The results show that CysSeSeCys alone causes moderate induction of these three genes. However, CysSeSeCys pretreatment resulted in a suppression of radiation-induced enhancement of p21 and GADD45α expression, but did not affect p53 expression. Further analysis of radiation-induced oxidative stress markers in the same tissue indicated that CysSeSeCys significantly inhibits lipid peroxidation and prevents the depletion of antioxidant enzymes and glutathione (GSH) levels. Additionally, it also prevents radiation-induced DNA damage in other radiation sensitive cellular systems like peripheral leukocytes and bone marrow, which was evident by a decrease in comet parameters and micronucleated polychromatic erythrocytes (mn-PCEs) frequency, respectively. Based on these observations, it is concluded that CysSeSeCys exhibits antigenotoxic effects, reduces radiation-induced oxidative stress, and is a promising candidate for future exploration as a radioprotector.

Effect of functional groups on antioxidant properties of substituted selenoethers.

Selenoethers attached to functional groups through propyl chain viz., bis(3-carboxypropyl)selenide (SeBA), bis(3-hydroxypropyl)selenide (SePOH) and bis(3-aminopropyl)selenide dihydrochloride (SePAm), have been examined for their ability to inhibit peroxyl radical mediated DNA damage, peroxyl radical scavenging ability and glutathione peroxidase (GPx) like activity. The DNA damage was monitored by gel electrophoresis, bimolecular rate constants for scavenging of model peroxyl radical were determined by pulse radiolysis and the GPx activity was followed by their ability to reduce hydrogen peroxide in the presence of glutathione utilizing NADPH decay and HPLC analysis. Among these compounds, SeBA showed maximum DNA protecting activity and it was also the most efficient in scavenging peroxyl radicals with the highest GPx mimicking activity. Quantum chemical calculations confirmed that SeBA with the highest energy level of HOMO (highest occupied molecular orbital) is the easiest to undergo oxidation and therefore exhibits better radical scavenging, GPx mimicking and DNA protecting activity than SePOH or SePAm.

Hepatoprotective, immunomodulatory, and anti-inflammatory activities of selenocystine in experimental liver injury of rats.

The study was evaluated to investigate the efficacy of selenocystine (CysSeSeCys), a well-known organoselenium compound, on the prevention of carbon tetrachloride (CCl(4))-induced acute hepatic injury in Wistar rats. Forty healthy male Wistar rats were utilized in this study. Acute hepatotoxicity was induced by CCl(4) intoxication in rats. Serum biological analysis, oxidative stress, immune parameters, and gene expression of COX-2 and CYP2E1 were carried out. Pretreatment of CysSeSeCys prior to CCl(4) administration significantly prevented an increase in serum hepatic enzymatic activities. In addition, pretreatment of CysSeSeCys significantly prevented the formation of ROS, MDA, depletion of glutathione, and alteration of antioxidant enzyme activities in the liver of CCl(4)-intoxicated rats. This study also revealed that pretreatment with CysSeSeCys normalized the levels of interleukin 6 and10, IgG, and CD4 cell count. Pretreatment of CysSeSeCys significantly reversed COX-2 inflammatory response and the upregulation of CYP2E1 expression as well. Histopathological changes induced by CCl(4) were also significantly attenuated by CysSeSeCys pretreatment. CysSeSeCys has a potent hepatoprotective effect on CCl(4)-induced liver injury in rats through its antioxidative, immunomodulatory and anti-inflammatory activity.

Radiation and quantum chemical studies of chalcone derivatives.

The reactions of oxidizing radicals ((*)OH, Br(2)(*-), and SO(4)(*-)) with -OH-, -CH(3)-, or -NH(2)-substituted indole chalcones and hydroxy benzenoid chalcones were studied by radiation and quantum chemical methods. The (*)OH radical was found to react by addition at diffusion-controlled rates (k = 1.1-1.7 x 10(10) dm(3) mol(-1) s(-1)), but Br(2)(*-) radical reacted by 2 orders of magnitude lower. Quantum chemical calculations at the B3LYP/6-31+G(d,p) level of theory have shown that the (C2-OH)(*), (C11-OH)(*), and (C10-OH)(*) adducts of the indole chalcones and the (C7-OH)(*) and (C8-OH)(*) adducts of the hydroxy benzenoid chalcones are more stable with DeltaH = -39 to -28 kcal mol(-1) and DeltaG = -32 to -19 kcal mol(-1). This suggests that (*)OH addition to the alpha,beta-unsaturated bond is a major reaction channel in both types of chalcones and is barrierless. The stability and lack of dehydration of the (*)OH adducts arise from two factors: strong frontier orbital interaction due to the low energy gap between interacting orbitals and the negligible Coulombic repulsion due to small absolute values of Mulliken charges. The transient absorption spectrum measured in the (*)OH radical reaction with all the indole chalcone derivatives exhibited a maximum at 390 nm, which is in excellent agreement with the computed value (394 nm). The formation of three phenolic products under steady-state radiolysis is in line with the three stable (*)OH adducts predicted by theory. Independent of the substituent, identical spectra (lambda(max) = 330-360 and approximately 580 nm) were obtained on one-electron oxidation of the three indole chalcones. MO calculations predict the deprotonation from the -NH group is more efficient than from the substituent due to the larger electron density on the N1 atom forming the chalcone indolyl radical. Its reduction potential was determined to be 0.56 V from the ABTS(*-)/ABTS(2-) couple. In benzenoid chalcones, the (*)OH adduct spectrum is characterized by a peak at 270 nm and a broad maximum centered in the range 430-450 nm with an intense bleaching at 340 nm. The spectrum formed by electron transfer in these derivatives with lambda(max) = 280 and 380 nm (epsilon(280) = 5000 dm(3) mol(-1) cm(-1) and epsilon(380) = 700 dm(3) mol(-1) cm(-1)) was assigned to its phenoxyl radical. Our pulse radiolysis experiments in combination with quantum chemical calculations demonstrate that chalcones are efficient scavengers of damaging oxyl radicals.