Hydrophilic CO-Releasing Material of PEGlyated Ruthenium Carbonyl Complex

The poor water-solubility and instability of Ru(II) carbonyl complex hamper the therapeutic application as CO releasing materials (CO-RMs). To enhance the hydrophilicity and bio-utility of CO, a robust Ru(I) carbonyl sawhorse skeleton was grafted with water-soluble PEGylated sidearm. In this case, 12 PEGylated sawhorse Ru₂(CO)₄ complexes were prepared with satisfactory yields and characterized by IR and ¹H- and ¹³C- NMR. X-ray diffraction analysis of CO-RM 8, 13 and 14 revealed the featured diruthenium sawhorse skeleton and PEGylated axial ligands. The flask-shaking method measures the water-solubility of CO-RMs, indicating that both bridging carboxylate ligands and PEGlyated axial ligands regulate the hydrophilicity of these CO-RMs. Under photolysis conditions, CO-RM 4–13 sustainable released therapeutic amounts of CO in the myoglobin assay. The correlation of the CO release kinetics and hydrophilicity of CO-RMs demonstrated that the more hydrophilic CO-RM released CO faster. The biological test found that the low cytotoxic CO-RM 4 showed a specific anticancer activity toward HT-29 tumour cells.

Proteinase 3 contributes to endothelial dysfunction in an experimental model of sepsis

In sepsis-induced inflammation, polymorphonuclear neutrophils (PMNs) contribute to vascular dysfunction. The serine proteases proteinase 3 (PR3) and human leukocyte elastase (HLE) are abundant in PMNs and are released upon degranulation. While HLE's role in inflammation-induced endothelial dysfunction is well studied, PR3's role is largely uninvestigated. We hypothesized that PR3, similarly to HLE, contributes to vascular barrier dysfunction in sepsis. Plasma PR3 and HLE concentrations and their leukocyte mRNA levels were measured by ELISA and qPCR, respectively, in sepsis patients and controls. Exogenous PR3 or HLE was applied to human umbilical vein endothelial cells (HUVECs) and HUVEC dysfunction was assessed by FITC-dextran permeability and electrical resistance. Both PR3 and HLE protein and mRNA levels were significantly increased in sepsis patients (P < 0.0001 and P < 0.05, respectively). Additionally, each enzyme independently increased HUVEC monolayer FITC-dextran permeability (P < 0.01), and decreased electrical resistance in a time- and dose-dependent manner (P < 0.001), an effect that could be ameliorated by novel treatment with carbon monoxide-releasing molecule 3 (CORM-3). The serine protease PR3, in addition to HLE, lead to vascular dysfunction and increased endothelial permeability, a hallmark pathological consequence of sepsis-induced inflammation. CORMs may offer a new strategy to reduce serine protease-induced vascular dysfunction.

Modulation of Diverse Procoagulant Venom Activities by Combinations of Platinoid Compounds

Procoagulant snake venoms have been inhibited by the ruthenium containing compounds CORM-2 and RuCl₃ separately, presumably by interacting with critical histidine or other sulfur-containing amino acids on key venom enzymes. However, combinations of these and other platinoid containing compounds could potentially increase, decrease or not affect the procoagulant enzyme function of venom. Thus, the purpose of this investigation was to determine if formulations of platinoid compounds could inhibit venom procoagulant activity and if the formulated compounds interacted to enhance inhibition. Using a human plasma coagulation kinetic model to assess venom activity, six diverse venoms were exposed to various combinations and concentrations of CORM-2, CORM-3, RuCl₃ and carboplatin (a platinum containing compound), with changes in venom activity determined with thrombelastography. The combinations of CORM-2 or CORM-3 with RuCl₃ were found to enhance inhibition significantly, but not in all venoms nor to the same extent. In sharp contrast, carboplatin-antagonized CORM-2 mediated the inhibition of venom activity. These preliminary results support the concept that platinoid compounds may inhibit venom enzymatic activity at the same or different molecular sites and may antagonize inhibition at the same or different sites. Further investigation is warranted to determine if platinoid formulations may serve as potential antivenoms.

Photoactivatable Surface-Functionalized Diatom Microalgae for Colorectal Cancer Targeted Delivery and Enhanced Cytotoxicity of Anticancer Complexes

Systemic toxicity and severe side effects are commonly associated with anticancer chemotherapies. New strategies based on enhanced drug selectivity and targeted delivery to cancer cells while leaving healthy tissue undamaged can reduce the global patient burden. Herein, we report the design, synthesis and characterization of a bio-inspired hybrid multifunctional drug delivery system based on diatom microalgae. The microalgae's surface was chemically functionalized with hybrid vitamin B12-photoactivatable molecules and the materials further loaded with highly active rhenium(I) tricarbonyl anticancer complexes. The constructs showed enhanced adherence to colorectal cancer (CRC) cells and slow release of the chemotherapeutic drugs. The overall toxicity of the hybrid multifunctional drug delivery system was further enhanced by photoactivation of the microalgae surface. Depending on the construct and anticancer drug, a 2-fold increase in the cytotoxic efficacy of the drug was observed upon light irradiation. The use of this targeted drug delivery strategy, together with selective spatial-temporal light activation, may lead to lower effective concentration of anticancer drugs, thereby reducing medication doses, possible side effects and overall burden for the patient.

Ruthenium, Not Carbon Monoxide, Inhibits the Procoagulant Activity of Atheris, Echis, and Pseudonaja Venoms

The demonstration that carbon monoxide releasing molecules (CORMs) affect experimental systems by the release of carbon monoxide, and not via the interaction of the inactivated CORM, has been an accepted paradigm for decades. However, it has recently been documented that a radical intermediate formed during carbon monoxide release from ruthenium (Ru)-based CORM (CORM-2) interacts with histidine and can inactivate bee phospholipase A₂ activity. Using a thrombelastographic based paradigm to assess procoagulant activity in human plasma, this study tested the hypothesis that a Ru-based radical and not carbon monoxide was responsible for CORM-2 mediated inhibition of Atheris,Echis, and Pseudonaja species snake venoms. Assessment of the inhibitory effects of ruthenium chloride (RuCl₃) on snake venom activity was also determined. CORM-2 mediated inhibition of the three venoms was found to be independent of carbon monoxide release, as the presence of histidine-rich albumin abrogated CORM-2 inhibition. Exposure to RuCl₃ had little effect on Atheris venom activity, but Echis and Pseudonaja venom had procoagulant activity significantly reduced. In conclusion, a Ru-based radical and ion inhibited procoagulant snake venoms, not carbon monoxide. These data continue to add to our mechanistic understanding of how Ru-based molecules can modulate hemotoxic venoms, and these results can serve as a rationale to focus on perhaps other, complementary compounds containing Ru as antivenom agents in vitro and, ultimately, in vivo.

Characterization of L-amino Acid Oxidase Derived from Crotalus adamanteus Venom: Procoagulant and Anticoagulant Activities

Snake venom enzymes of the L-amino acid oxidase (LAAO) class are responsible for tissue hemorrhage, edema, and derangement of platelet function. However, what role, if any, these flavoenzymes play in altering plasmatic coagulation have not been well defined. Using coagulation kinetomic analyses (thrombelastograph-based), it was determined that the LAAO derived from Crotalus adamanteus venom displayed a procoagulant activity associated with weak clot strength (no factor XIII activation) similar to thrombin-like enzymes. The procoagulant activity was not modified in the presence of reduced glutathione, demonstrating that the procoagulant activity was likely due to deamination, and not hydrogen peroxide generation by the LAAO. Further, unlike the raw venom of the same species, the purified LAAO was not inhibited by carbon monoxide releasing molecule-2 (CORM-2). Lastly, exposure of the enzyme to phenylmethylsulfonyl fluoride (PMSF) resulted in the LAAO expressing anticoagulant activity, preventing contact activation generated thrombin from forming a clot. In sum, this investigation for the first time characterized the LAAO of a snake venom as both a fibrinogen polymerizing and an anticoagulant enzyme acting via oxidative deamination and not proteolysis as is the case with thrombin-like enzymes (e.g., serine proteases). Using this thrombelastographic approach, future investigation of purified enzymes can define their biochemical nature.

[Effect of carbon monoxide releasing molecule on experimental periodontitis in rats]

OBJECTIVE

To evaluate the effects of carbon monoxide releasing molecule-2 (CORM-2) on experimental periodontitis in rats.

METHODS

Forty-two Wistar rats were divided into three groups. Rats in the normal group (NL group) did not undergo any procedure, whereas the other rats were ligatured and treated with saline solution (NaCl 0.9%) (LO group) or treated with CORM-2 (10 mg kg(-1) per day) (CO group). A 3-0 silk suture was placed around the mandibular first molars. Rats were sacrificed after 3, 7, and 10 d. Blood samples were collected from all animals for tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) analysis. Changes in alveolar bone levels were measured clinically, and periodontal tissues were histopathologically examined to assess the infiltration of inflammatory cells.

RESULTS

Ligature placement increased alveolar bone loss and inflammatory cell infiltration in periodontal tissue. Alveolar bone loss in CO group was significantly higher than that in NL group, but was lower than that in LO group (P<0.05). The ratio of inflammatory cell infiltration in LO group was significantly higher than that in CO and NL groups, and that in CO group was lower than in LO group (P<0.05). Serum levels of TNF-alpha and IL-1beta in the LO group were significantly higher than those in the CO and NL groups, and those in CO group were lower than in LO group (P<0.05).

CONCLUSION

Systemic administration of CORM-2 reduced periodontal inflammation and alveolar bone loss in experimental periodontitis in rats.