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Because of its multifaceted anti-inflammatory and immunomodulatory effects, delivering type-I interferon to Kupffer cells has the potential to function as a novel type of therapy for the treatment of various types of hepatitis. We report herein on the preparation of a Kupffer cell targeting type-I interferon, an albumin-IFNa2b fusion protein that contains highly mannosylated N-linked oligosaccharide chains, Man-HSA(D494N)-IFNa2b, attached by combining albumin fusion technology and site-directed mutagenesis. The presence of this unique oligosaccharide permits the protein to be efficiently, rapidly and preferentially distributed to Kupffer cells. Likewise IFNa2b, Man-HSA(D494N)-IFNa2b caused a significant induction in the mRNA levels of IL-10, IL-1Ra, PD-L1 in RAW264.7 cells and mouse isolated Kupffer cells, and these inductions were largely inhibited by blocking the interferon receptor. These data indicate that Man-HSA(D494N)-IFNa2b retained the biological activities of type-I interferon. Man-HSA(D494N)-IFNa2b significantly inhibited liver injury in Concanavalin A (Con-A)-induced hepatitis model mice, and consequently improved their survival rate. Moreover, the post-administration of Man-HSA(D494N)-IFNa2b at 2?h after the Con-A challenge also exerted hepato-protective effects. In conclusion, this proof-of-concept study demonstrates the therapeutic effectiveness and utility of Kupffer cell targeting type-I interferon against hepatitis via its anti-inflammatory and immunomodulatory actions.

Products of ultraviolet (UV) irradiation such as reactive oxygen species (ROS) and nitric oxide (NO) stimulate melanin synthesis. Reactive sulfur species (RSS) have been shown to have strong ROS and NO scavenging effects. However, the instability and low retention of RSS limit their use as inhibitors of melanin synthesis. The free thiol at Cys34 on human serum albumin (HSA) is highly stable, has a long retention and possess a high reactivity for RSS. We report herein on the developm ent of an HSA based RSS delivery system. Sulfane sulfur derivatives released from sodium polysulfides (Na 2 S n ) react readily with HSA. An assay for estimating the elimination of sulfide from polysulfide showed that almost all of the sulfur released from Na 2 S n bound to HSA. The Na 2 S n -treated HSA was found to efficiently scavenge ROS and NO produced from chemical reagents. The Na 2 S n -treated HSA was also found to inhibit melanin synthesis in B16 melanoma cells and this inhibition was independent of the number of added sulfur atoms. In B16 melanoma cells, the Na 2 S n -treated HSA also inhibited the levels of ROS and NO induced by UV radiation. Finally, the Na 2 S n -treated HSA inhibited melanin synthesis from L-DOPA and mushroom tyrosinase and suppressed the extent of aggregation of melanin pigments. These data suggest that Na 2 S n -treated HSA inhibits tyrosinase activity for melanin synthesis via two pathways; by directly inhibiting ROS signaling and by scavenging NO. These findings indicate that Na 2 S n -treated HSA has potential to be an attractive and effective candidate for use as a skin whitening agent.

© 2018 Human serum albumin (HSA) is a superior carrier for delivering extracellular drugs. However, the development of a cell-penetrating HSA remains a great challenge due to its low membrane permeability. We report herein on the design of a series of palmitoyl-poly-arginine peptides (CPPs) and an evaluation of their cell-penetrating effects after forming a complex with HSA for use in intracellular drug delivery. The palmitoyl CPPs forms a stable complex with HSA by anchoring itself to the high affinity palmitate binding sites of HSA. Among the CPPs evaluated, a cyclic polypeptide composed of D-dodecaarginines, palmitoyl-cyclic-(D-Arg) 12 was the most effective for facilitating the cellular uptake of HSA by HeLa cells. Such a superior cell-penetrating capability is primarily mediated by macropinocytosis. The effect of the CPP on pharmacological activity was examined using three drugs loaded in HSA via three different methods: a) an HSA-paclitaxel complex, b) an HSA-doxorubicin covalent conjugate and c) an HSA-thioredoxin fusion protein. The results showed that cell-penetrating efficiency was increased with a corresponding and significant enhancement in pharmacological activity. In conclusion, palmitoyl-cyclic-(D-Arg) 12 /HSA is a versatile cell-penetrating drug delivery system with great potential for use as a nano-carrier for a wide diversity of pharmaceutical applications.

© 2017 Elsevier B.V. Zinc (Zn) is a co-factor for a vast number of enzymes, and functions as a regulator for immune mechanism and protein synthesis. However, excessive Zn release induced in pathological situations such as stroke or transient global ischemia is toxic. Previously, we demonstrated that the interaction of Zn and copper (Cu) is involved in the pathogenesis of Alzheimer's disease and vascular dementia. Furthermore, oxidative stress has been shown to play a significant role in the pathogenesis of various metal ions induced neuronal death. Thioredoxin-Albumin fusion (HSA-Trx) is a derivative of thioredoxin (Trx), an antioxidative protein, with improved plasma retention and stability of Trx. In this study, we examined the effect of HSA-Trx on Cu 2+ /Zn 2+ -induced neurotoxicity. Firstly, HSA-Trx was found to clearly suppress Cu 2+ /Zn 2+ -induced neuronal cell death in mouse hypothalamic neuronal cells (GT1-7 cells). Moreover, HSA-Trx markedly suppressed Cu 2+ /Zn 2+ -induced ROS production and the expression of oxidative stress related genes, such as heme oxygenase-1. In contrast, HSA-Trx did not affect the intracellular levels of both Cu 2+ and Zn 2+ after Cu 2+ /Zn 2+ treatment. Finally, HSA-Trx was found to significantly suppress endoplasmic reticulum (ER) stress response induced by Cu 2+ /Zn 2+ treatment in a dose dependent manner. These results suggest that HSA-Trx counteracted Cu 2+ /Zn 2+ -induced neurotoxicity by suppressing the production of ROS via interfering the related gene expressions, in addition to the highly possible radical scavenging activity of the fusion protein. Based on these findings, HSA-Trx has great potential as a promising therapeutic agent for the treatment of refractory neurological diseases.

A wide variety of drugs bind to human serum albumin (HSA) at its two principal sites, namely site I and site II. A number of reports indicate that drug binding to these two binding sites are not completely independent, and that interactions between ligands of these two discrete sites can play a role. In this study, the effect of the binding of long-chain fatty acids on the interactive binding between dansyl-L-asparagine (DNSA; site I ligand) and ibuprofen (site II ligand) at pH6.5 was examined. Binding experiments showed that the binding of sodium oleate (Ole) to HSA induces conformational changes in the molecule, which, in turn, changes the individual binding of DNSA and ibuprofen, as well as the mode of interaction between these two ligands from a 'competitive-like' allosteric interaction in the case of the defatted HSA conformer to a 'nearly independent' binding in the case of non-defatted HSA conformer. Circular dichroism measurements indicated that ibuprofen and Ole are likely to modify the spatial orientation of DNSA at its binding site. Docking simulations suggest that the long-distance electric repulsion between DNSA and ibuprofen on defatted HSA contributes to a 'competitive-like' allosteric interaction, whereas extending the distance between ligands and/or increasing the flexibility or size of the DNSA binding site in fatted HSA evokes a change in the interaction mode to 'nearly independent' binding. The present findings provide further insights into the structural dynamics of HSA upon the binding of fatty acids, and its effects on drug binding and drug-drug interactions that occur on HSA.

© 2017 Elsevier Ltd In the latest trend of anticancer chemotherapy research, there were many macromolecular anticancer drugs developed based on enhanced permeability and retention (EPR) effect, such as albumin bound paclitaxel nanoparticle (nab- PTX, also called Abraxane ® ). However, cancers with low vascular permeability posed a challenge for these EPR based therapeutic systems. Augmenting the intrinsic EPR effect with an intrinsic vascular modulator such as nitric oxide (NO) could be a promising strategy. S-nitrosated human serum albumin dimer (SNO-HSA Dimer) shown promising activity previously was evaluated for the synergistic effect when used as a pretreatment agent in nab-PTX therapy against various tumor models. In the high vascular permeability C26 murine colon cancer subcutaneous inoculation model, SNO-HSA Dimer enhanced tumor selectivity of nab-PTX, and attenuated myelosuppression. SNO-HSA Dimer also augmented the tumor growth inhibition of nab-PTX in low vascular permeability B16 murine melanoma subcutaneous inoculation model. Furthermore, nab-PTX therapy combined with SNO-HSA Dimer showed higher antitumor activity and improved survival rate of SUIT2 human pancreatic cancer orthotopic model. In conclusion, SNO-HSA Dimer could enhance the therapeutic effect of nab-PTX even in low vascular permeability or intractable pancreatic cancers. The possible underlying mechanisms of action of SNO-HSA Dimer were discussed.

During pasteurization and storage of albumin products, Sodium octanoate (Oct) and N-acethyl-l-tryptophan (N-AcTrp) are used as the thermal stabilizer and the antioxidant for human serum albumin (HSA), respectively. We recently reported that N-acethyl-l-methionine (N-AcMet) is an antioxidant for HSA, which is superior to N-AcTrp when it is especially exposed to light during storage. The objective of the present study is to clarify the molecular mechanism responsible for the HSA protective effect of Oct and N-AcMet based on their ternary complex structure. Crystal structure of the HSA-Oct-N-AcMet complex showed that one N-AcMet molecule is bound to the entrance of drug site 1 of HSA, and its side chain, which is susceptible to the oxidation, is exposed to the solvent. At the same time, two Oct binding sites are observed in drug sites 1 and 2 of HSA, respectively, and each Oct molecule occupies the hydrophobic cavity in them. These results indicate the molecular mechanism responsible for the HSA stabilization by these small molecules as follows. N-AcMet seals the entrance of drug site 1 while it acts as an antioxidant for HSA. Oct is chiefly bound to drug site 2 of HSA and it increases the thermal stability of HSA because of the occupying the largest intra-cavity of sub-domain IIIA in HSA. These findings suggest that N-AcMet acts positively as useful stabilizer for albumin formulated products such as functionalized HSA and HSA fusion proteins.

Hydrogen sulfide (H2S) signaling involves polysulfide (RSSnSR') formation on various proteins. However, the current lack of sensitive polysulfide detection assays poses methodological challenges for understanding sulfane sulfur homeostasis and signaling. We developed a novel combined assay by modifying Sulfide Antioxidant Buffer (SAOB) to produce an “Elimination Method of Sulfide from Polysulfide” (EMSP) treatment solution that liberates sulfide, followed with methylene blue (MB) sulfide detection assay. The combined EMSP-MB sulfide detection assay performed on low molecular weight sulfur species showed that sulfide was produced from trisulfide compounds such as glutathione trisulfide and diallyl trisulfide, but not from the thiol compounds such as cysteine, cystine and glutathione. In the case of plasma proteins, this novel combined detection assay revealed that approximately 14.7, 1.7, 3.9, 3.7 sulfide mol/mol released from human serum albumin, a1-anti-trypsin, a1-acid glycoprotein and ovalbumin, respectively, suggesting that serum albumin is a major pool of polysulfide in human blood circulation. Taken together with the results of albumins of different species, the liberated sulfide has a good correlation with cysteine instead of methionine, indicating the site of incorporation of polysulfide is cysteine. With this novel sulfide detention assay, approximately 8,000, 120 and 1100 µM of polysulfide concentrations was quantitated in human healthy plasma, saliva and tear, respectively. Our promising polysulfide specific detection assay can be a very important tool because quantitative determination of polysulfide sheds light on the functional consequence of protein-bound cysteine polysulfide and expands the research area of reactive oxygen to reactive polysulfide species.

Recently, hydropersulfide (RSSH) was found to exist in mammalian tissues and fluids. Cysteine hydropersulfide can be found in free cysteine residues as well as in proteins, and it has potent antioxidative activity. Human serum albumin (HSA) is the most abundant protein in mammalian serum. HSA possesses a free thiol group in Cys-34 that could be a site for hydropersulfide formation. HSA hydropersulfide of high purity as a positive control was prepared by treatment of HSA with Na2S. The presence of HSA hydropersulfide was confirmed by spectroscopy and ESI-TOFMS analysis where molecular weights of HSA hydropersulfide by increments of approximately 32 Da (Sulfur atom) were detected. The fluorescent probe results showed that Alexa Fluor 680 conjugated maleimide (Red-Mal) was a suitable assay and bromotrimethylammoniumbimane bromide appeared to be a selective reagent for hydropersulfide. The effect of oxidative stress related disease on the existence of albumin hydropersulfides was examined in rat 5/6 nephrectomy model of chronic kidney disease (CKD). Interestingly, the level of hydropersulfides in rat 5/6 nephrectomy model serum was decreased by a uremic toxin that increases oxidative stress in rat 5/6 nephrectomy model. Furthermore, we demonstrated that the levels of HSA hydropersulfide in human subjects were reduced in CKD but restored by hemodialysis using Red-Mal assay. We conclude that HSA hydropersulfide could potentially play an important role in biological anti-oxidative defense, and it is a promising diagnostic and therapeutic marker of oxidative diseases.

Low concentrations of exogenous carbon monoxide (CO) have been reported to be useful for the treatment of various disorders related to inflammation and oxidative stress. However, a number of obstacles make it difficult to use CO in vivo. Among these are, at high concentrations, it is toxic and the fact that it is difficult to control its delivery in the body. Hemoglobin-encapsulated liposomes, Hemoglobin-vesicles (HbV), have the potential for use as a new type of nano-sized CO donor, referred to as CO-bound HbV (CO-HbV). In this study, we investigated the potential of CO-HbV as a CO donor in terms of toxicity and therapeutic efficacy using an experimental colitis model. Toxicological assessments of CO-HbV showed no severe adverse effects including death, and clinical laboratory tests and histopathological changes remained normal for 28 days after the administration of doses up to 1400 mg Hb/kg. We then evaluated the therapeutic efficacies of CO-HbV on dextran sulfate sodium (DSS)-induced colitis model mice. A single administration of CO-HbV at 3 days from beginning of the DSS treatment dramatically improved colitis symptoms, colonic histopathological changes and the duration of survival compared to both saline and HbV administration. In addition, the therapeutic effects of CO-HbV on colitis can be attributed to a decreased level of neutrophil infiltration, the production of pro-inflammatory cytokines and oxidative injuries. Interestingly, it appears that an increase in anti-inflammatory cytokine production contributes, in part, to therapeutic effects of CO-HbV in the treatment of colitis. These safety and efficacy profiles of CO-HbV suggest that it has the potential for use as a drug for treating, not only colitis but also a variety of other disorders associated with inflammation and oxidative stress.

Poly-S-nitrosated human serum albumin (Poly-SNO-HSA) delivered and accumulated nitric oxide (NO) in tumors and induces apoptosis. Tumor hypoxia is strongly associated with malignant progression and tumor resistance to therapy. In this study, we examined the cytotoxic effect of Poly-SNO-HSA under hypoxia on the murine colon 26 adenocarcinoma (C26) cells in vitro and in vivo. Under hypoxia, at about 4 times LD50 dose of Poly-SNO-HSA in vitro, the reactive oxygen species production was hindered but apoptotic cells were induced via cGMP pathway as the effect was suppressed by a soluble guanylate cyclase inhibitor, NS2028. The apoptosis induction effect of low dose Poly-SNO-HSA on C26 cells in vitro under hypoxia can be restored by a phosphodiesterase 5 (PDE5) inhibitor, vardenafil. In C26-bearing mice, Poly-SNO-HSA/vardenafil combination treatment significantly suppressed the tumor volume compared with Poly-SNO-HSA or vardenafil treatment alone. Furthermore, the core tumor tissues showed increased expression of caspase-3 than the non-core tissue. The expression of caspase-3 appeared to overlap with the hypoxic zone of tumor tissues. Similar results were also obtained when the experiments were repeated using Epimedium extract, a natural herbal supplement with PDE5 inhibition activity. In conclusion, Poly-SNO-HSA/PDE5 inhibitors combination therapy is a promising approach for enhancing the anticancer therapeutic effects of Poly-SNO-HSA against not only anti-cancer drug resistance but also hypoxic stress related solid tumor resistance.

© 2015 Elsevier B.V. All rights reserved. The enhanced permeability and retention (EPR) effect is a unique phenomenon of solid tumors, and it can serve as a basis for the development of macromolecular anticancer therapy. We have previously found that recombinant human serum albumin dimer, and especially its S-nitrosated form (SNO-HSA-Dimer), is an enhancer of the EPR effect. In this study, we investigated the influence of SNO-HSA-Dimer on the anti-tumor effect of two types of macromolecular anti-tumor drugs, namely N-(2-hydroxypropyl)methacrylamide polymer conjugated with zinc protoporphyrin, which forms micelles and can be used for fluorescence studies. The other was PEGylated liposomal doxorubicin (Doxil), a typical example of a stealth liposome approved for medical usage. In mice having C26 tumors with highly permeable vasculature, SNO-HSA-Dimer increases tumor accumulation of the drugs by a factor 3-4 and thereby their anti-tumor effects. Experiments with Evans blue revealed increased EPR effect in all parts of the tumor. Furthermore, SNO-HSA-Dimer improves the anti-metastatic effects of Doxil and reduces its minor uptake in non-tumorous organs such as liver and kidney. Tumor accumulation of Doxil in B16 tumors, which are characterized by a low permeable vasculature, increased even more (6-fold) in the presence of SNO-HSA-Dimer, and the improved accumulation lead to decreased tumor volume and increased survival of the animals. The administration of SNO-HSA-Dimer itself is safe, because it has no effect on blood pressure, heart rate or on several biochemical parameters. The present findings indicate that SNO-HSA-Dimer is promising for enhancing the EPR effect and consequently the specific, therapeutic effects of macromolecular anticancer drugs.

Rhabdomyolysis-Associated acute kidney injury (AKI) is a serious life-Threatening condition. As such, more effective strategies are needed for its prevention. Thioredoxin-1 (Trx), a redox-Active and macrophage migration inhibitory factor (MIF) modulating protein, has a short retention time in the blood. We examined the renoprotective effect of long acting Trx that was genetically fused with human serum albumin (HSA-Trx) against glycerol-induced AKI. An intravenous HSA-Trx pre-Treatment attenuated the glycerol-induced decline in renal function, compared to a PBS, HSA or Trx alone. HSA-Trx caused a reduction in the tubular injuries and in the number of apoptosis-positive tubular cells. Renal superoxide, 8-hydroxy deoxyguanosine, nitrotyrosine and the plasma Cys34-cysteinylated albumin were clearly suppressed by the HSA-Trx treatment. Prior to decreasing TNF-a and IL-6, HSA-Trx suppressed an increase of plasma MIF level. In LLC-PK1 cells, HSA-Trx decreased the level of reactive oxygen species and lactate dehydrogenase release induced by myoglobin. HSA-Trx treatment resulted in a threefold increase in the survival of lethal glycerol-Treated mice. The post-Administration of HSA-Trx at 1 and 3â €‰hr after glycerol injection exerted a significant renoprotective effect. These results suggest HSA-Trx has potential for use in the treatment of rhabdomyolysis-Associated AKI via its extended effects of modulating oxidative stress and MIF.

Human serum albumin (HSA) is synthesized predominantly in the liver, and has an extraordinarily long circulatory half-life (~19 days). Since HSA is responsible for 80% of the colloidal osmotic pressure of plasma, the patients with hypoalbuminemia are typically given a plasma expander to increase the plasma volume. Clinically, using HSA as an extender is preferable to other options, such as dextran, hydroxylethyl starch, due to its long retention in plasma. However, the circulatory half-life of HSA is significantly- impacted by structural changes of HSA and pathological conditions. Recent scientific advances have revealed new information regarding the factors that influence the pharmacokinetic properties of HSA. In this chapter, we provide an overview of the impact of HSA structure and biotransformation upon the pharmacokinetic properties of HSA, and discuss new possibilities for the therapeutic potential of HSA based on its pharmacokinetic properties.

Uric acid exerts an important antioxidant effect against external oxidative stress under physiological conditions. However, uric acid itself can increase oxidative stress via reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation in adipocytes and vascular cells. Uric acid transporter 1 is involved in the generation of this oxidative stress. Furthermore, uric acid locally activates the renin-angiotensin system, thus producing angiotensin II and subsequently increasing intracellular oxidative stress. Ben-zbromarone has been reported to suppress uric acid reabsorption via uric acid transporter 1 inhibition in renal tubular cells. In this study we evaluated the in vitro antioxidant effect of benzbromarone from several perspectives. First, the direct radical-trapping capacity of benzbromarone was measured by chemilumines-cence assay and electron paramagnetic resonance spectroscopy. Second, the intracellular antioxidant activity of benzbromarone in hyperuricemia was evaluated using endothelial cells. In light of these results, benz-bromarone is hypothesized directly to scavenge the superoxide anion radical. In addition, benzbromarone inhibited reactive oxygen species production that was induced by angiotensin II or uric acid in endothelial cells. These findings suggest that benzbromarone possesses the ability directly to scavenge radicals and may act as an antioxidant against uric acid and angiotensin II-induced oxidative stresses in endothelial cells at therapeutically achievable levels in blood.

Since reactive oxygen species (ROS) derived from Kupffer cells (KC), especially CD68+ KC, play a key role in the induction of hepatic oxidative stress and injuries, we newly developed a polythiolated- and mannosylated-human serum albumin (SH-Man-HSA), a novel nano-antioxidant for delivering thiol to CD68+ KC. In vitro electron paramagnetic resonance (EPR) coupled with an in vivo pharmacokinetic and immunohistochemical study showed that SH-Man-HSA possessed powerful radical scavenging activity and was rapidly and selectively delivered thiols to the liver via mannose receptor (CD206) presented on the CD68+ cells surface. SH-Man-HSA significantly improved the survival rate of concanavalin-A (Con-A) treated mice. Moreover, SH-Man-HSA exhibited excellent hepato-protective action, not by influencing TNF or IFN-? production that closely associated with Con-A induced hepatitis, but by suppressing ROS production. Interestingly, such protective effect of SH-Man-HSA was superior to N-acetylcysteine (NAC). This could be due to the difference in the inhibition of hepatic oxidative stress between two antioxidant depending upon their potential of thiol delivery to liver. Similar results were also observed for acetaminophen (APAP)-induced hepatopathy models. Flow cytometric data further confirmed that an increase of F4/80+/ROS+ cells was dramatically decreased by SH-Man-HSA. The administration of SH-Man-HSA at 4 hours following a Con-A or APAP injection also exhibited profound hepato-protective action against two experimental hepatitis models, while this was not observed in the case of NAC. Therefore, SH-Man-HSA has a great potential for use as a rescue therapy for hepatopathy as a nano-antioxidant because of its efficient and rapid delivery of thiols to CD68+/CD206+ KC.

Objectives The half-life of fatty acid-conjugated antidiabetic drugs are prolonged through binding to albumin, but this may not occur in diabetic patients with nephropathy complicated with hypoalbuminemia. We previously showed that human serum albumin (HSA) dimerized at the protein's Cys34 by 1,6-bis(maleimido)hexane has longer half-life than the monomer under high permeability conditions. The aim of this study was to investigate the superior ability of this HSA dimer as a plasma-retaining agent for fatty acid conjugated antidiabetic drugs. Methods The diabetic nephropathy rat model was prepared by administering a single injection of streptozotocin (STZ) intravenously, and the pharmacokinetic properties of HSA monomer and dimer were evaluated. Site-specific fluorescent probe displacement experiments were performed using warfarin and dansylsarcosine as site I and site II specific fluorescent probes, respectively. Key findings The half-life of the HSA dimer in STZ-induced diabetic nephropathy model rats was 1.5 times longer than the HSA monomer. The fluorescent probe displacement experiment results for HSA monomer and dimer were similar, where fatty acid-conjugated antidiabetic drugs displaced dansylsarcosine but not warfarin in a concentration-dependent manner. Conclusions The HSA dimer shows potential for use as a plasma-retaining agent for antidiabetic drugs due to its favourable pharmacokinetic properties.

Curcuminoids are a group of compounds with a similar chemical backbone structure but containing different numbers of methoxy groups that have therapeutic potential due to their anti-inflammatory and anti-oxidant properties. They mainly bind to albumin in plasma. These findings influence their body disposition and biological activities. Spectroscopic analysis using site specific probes on human serum albumin (HSA) clearly indicated that curcumin (Cur), demethylcurcumin (Dmc) and bisdemethoxycurcumin (Bdmc) bind to both Site I (sub-site Ia and Ib) and Site II on HSA. At pH 7.4, the binding constants for Site I were relatively comparable between curcuminoids, while the binding constants for Site II at pH 7.4 were increased in order Cur , Dmc , Bdmc. Binding experiments using HSA mutants showed that Trp214 and Arg218 at Site I, and Tyr411 and Arg410 at Site II are involved in the binding of curcuminoids. The molecular docking of all curcuminoids to the Site I pocket showed that curcuminoids stacked with Phe211 and Trp214, and interacted with hydrophobic and aromatic amino acid residues. In contrast, each curcuminoid interacted with Site II in a different manner depending whether a methoxy group was present or absent. A detailed analysis of curcuminoids-albumin interactions would provide valuable information in terms of understanding the pharmacokinetics and the biological activities of this class of compounds.

Overdoses of acetaminophen (APAP) are a major cause of acute liver failure. N-acetylcysteine (NAC) is the standard therapy for the patients with such an overdose because oxidative stress plays an important role in the pathogenesis of APAP-induced hepatitis. However, NAC is not sufficiently efficacious. We previously developed a recombinant human serum albumin (HSA)-thioredoxin 1 (Trx) fusion protein (HSA-Trx), designed to overcome the unfavorable pharmacokinetic and short pharmacological properties of Trx, an endogenous protein with anti-oxidative and anti-inflammatory properties. In this study, we investigated the therapeutic impact of HSA-Trx in mice with APAP-induced hepatitis. The systemic administration of HSA-Trx significantly improved the survival rate of mice treated with a lethal dose of APAP compared with saline. HSA-Trx strongly attenuated plasma transaminases in APAP-induced hepatitis mice compared with HSA or Trx, components of the fusion protein. HSA-Trx also markedly caused a diminution in the histopathological features of hepatic injuries and the number of apoptosis-positive hepatic cells. In addition, an evaluation of oxidative stress markers and plasma cytokine and chemokine levels clearly showed that HSA-Trx significantly improved the breakdown of hepatic redox conditions and inflammation caused by the APAP treatment. HSA-Trx also significantly decreased oxidative and nitrosative/nitrative stress induced by SIN-1 in vitro. Finally, HSA-Trx, but not the NAC treatment at 4 hours after APAP injection, significantly inhibited the elevation in plasma transaminases levels. In conclusion, the findings suggest that HSA-Trx has considerable potential for use as a novel therapeutic agent for APAP-induced hepatitis, due to its long-lasting anti-oxidative and anti-inflammatory effects.

The degree of oxidized cysteine (Cys) 34 in human serum albumin (HSA), as determined by high performance liquid chromatography (HPLC), is correlated with oxidative stress related pathological conditions. In order to further characterize the oxidation of Cys34-HSA at the molecular level and to develop a suitable analytical method for a rapid and sensitive clinical laboratory analysis, the use of electrospray ionization time-of-flight mass spectrometer (ESI-TOFMS) was evaluated. A marked increase in the cysteinylation of Cys34 occurs in chronic liver and kidney diseases and diabetes mellitus. A significant positive correlation was observed between the Cys-Cys34-HSA fraction of plasma samples obtained from 229 patients, as determined by ESI-TOFMS, and the degree of oxidized Cys34-HSA determined by HPLC. The Cys-Cys34-HSA fraction was significantly increased with the progression of liver cirrhosis, and was reduced by branched chain amino acids (BCAA) treatment. The changes in the Cys-Cys34-HSA fraction were significantly correlated with the alternations of the plasma levels of advanced oxidized protein products, an oxidative stress marker for proteins. The binding ability of endogenous substances (bilirubin and tryptophan) and drugs (warfarin and diazepam) to HSA purified from chronic liver disease patients were significantly suppressed but significantly improved by BCAA supplementation. Interestingly, the changes in this physiological function of HSA in chronic liver disease were correlated with the Cys-Cys34-HSA fraction. In conclusion, ESI-TOFMS is a suitable high throughput method for the rapid and sensitive quantification of Cys-Cys34-HSA in a large number of samples for evaluating oxidative stress related chronic disease progression or in response to a treatment.

Reactive oxygen species (ROS) are the primary pathogenic molecules produced in viral lung infections. We previously reported on the use of a recombinant human serum albumin (HSA)-thioredoxin 1 (Trx) fusion protein (HSA-Trx) for extending the half-life Trx, an endogenous protein with anti-oxidant properties. As a result, it was possible to overcome the unfavorable pharmacokinetic and short pharmacological properties of Trx. We hypothesized that HSA-Trx would attenuate the enhanced ROS production of species such as hydroxyl radicals by neutrophils during an influenza viral infection. The levels of 8-hydroxy-2'-deoxyguanosine and 3-nitrotyrosine were used as indices of the anti-oxidant activity of HSA-Trx. In addition, the cytoprotective effects of HSA-Trx were examined in PR8 (H1N1) influenza virus-induced lung injured mice. The findings show that HSA-Trx reduced the number of total cells, neutrophils, and total protein in BALF of influenza virus-induced lung injured mice. The HSA-Trx treatment significantly decreased the level of 8-hydroxy-2'-deoxyguanosine and 3-nitrotyrosine, but failed to inhibit inducible nitric oxide synthase expression, in the lungs of the virus-infected mice. On the other hand, Tamiflu® treatment also significantly suppressed the production of inflammatory cells and neutrophil infiltration, as well as the protein level in BALF and lung histopathological alterations caused by the influenza virus. The suppressive effect of Tamiflu® was slightly stronger than that of HSA-Trx. Interestingly, Tamiflu® significantly decreased virus proliferation, while HSA-Trx had no effect. These results indicate that HSA-Trx may be of therapeutic value for the treatment of various acute inflammatory disorders such as influenza-virus-induced pneumonia, by inhibiting inflammatory-cell responses and suppressing the overproduction of NO in the lung.

Background: A strategy for preventing cisplatin nephrotoxicity due to enhanced oxidative stress and inflammatory response is highly desirable. Thioredoxin-1 (Trx), an endogenous redox-active protein, has a short retention time in the blood. A long acting form of Trx, human serum albumin-Trx (HSA-Trx), was produced by recombinant HSA fusion and its effectiveness in preventing cisplatin nephrotoxicity was examined. Methods: HSA-Trx was prepared in Pichia expression system. Cisplatin-induced nephropathy mouse model was established by a single administration of cisplatin. Results: Compared to saline, Trx or N-acetylcysteine, an intravenous administration of HSA-Trx attenuated the cisplatin-induced elevation in serum creatinine, blood urea nitrogen and urinary N-acetyl-ß-d-glucosaminidase along with the decrease in creatinine clearance. HSA-Trx caused a substantial reduction in the histological features of renal tubular injuries and the apoptosis-positive tubular cells. Changes in superoxide, 8-OHdG, glutathione and nitrotyrosine levels indicated that HSA-Trx significantly suppressed renal oxidative stress. HSA-Trx also suppressed the elevation of TNF-a, IL-1ß and IL-6. Administered fluorescein isothiocyanate-labeled HSA-Trx was found partially localized in the proximal tubular cells whereas majority remained in the blood circulation. Specific cellular uptake and the scavenging of intracellular reactive oxygen species by HSA-Trx were observed in HK-2 cells. Conclusion: HSA-Trx could be a novel and effective approach for preventing cisplatin nephrotoxicity due to its prolonged anti-oxidative and anti-inflammatory action not only in extracellular compartment but also inside the proximal tubular cell. General significance: We report the renoprotective effect of HSA-Trx against cisplatin nephrotoxicity. This work would enhance developing therapeutics against acute kidney injuries including cisplatin nephrotoxicity.