Enhancing radioprotection: A chitosan-based chelating polymer is a versatile radioprotective agent for prophylactic and therapeutic interventions against radionuclide contamination

To mitigate the risk of radioactive isotope dissemination, the development of preventative and curative measures is of particular interest. For mass treatment, the developed solution must be easily administered, preferably orally, with effective, nontoxic decorporating properties against a wide range of radioactive isotopes. Currently, most orally administered chelation therapy products are quickly absorbed into the blood circulation, where chelation of the radioactive isotope is a race against time due to the short circulation half-life of the therapeutic. This report presents an alternative therapeutic approach by using a functionalized chitosan (chitosan@DOTAGA) with chelating properties that remains within the gastrointestinal tract and is eliminated in feces, that can protect against ingested radioactive isotopes. The polymer shows important in vitro chelation properties towards different metallic cations of importance, including (Cs(I), Ir(III), Th(IV), Tl(I), Sr(II), U(VI) and Co(II)), at different pH (from 1 to 7) representing the different environments in the gastrointestinal tract. An in vivo proof of concept is presented on a rodent model of uranium contamination following an oral administration of Chitosan@DOTAGA. The polymer partially prevents the accumulation of uranium within the kidneys (providing a protective effect) and completely prevents its uptake by the spleen.

In vitro and in vivo toxicity of carbon dots with different chemical compositions

Carbon dots (CDs) are easy-obtained nanoparticles with wide range of biological activity; however, their toxicity after prolonged exposure is poorly investigated. So, in vitro and in vivo toxicity of CDs with the surfaces enriched with hydroxylated hydrocarbon chains and methylene groups (CD_GE), carboxyl and phenol groups accompanied with nitrogen (CD_3011), trifluoromethyl (CDF19) or toluidine and aniline groups (CDN19) were aimed to be discovered. CDs' in vitro toxicity was assessed on A549 cells (real-time cell analysis of impedance, fluorescence microscopy) after 24 h of incubation, and we observed no changes in cell viability and morphology. CDs' in vivo toxicity was assessed on C57Bl6 mice after multiple dosages (5 mg/kg subcutaneously) for 14 days. Lethality (up to 50%) was observed in CDN19 and CD_3011 groups on different days of dosing, accompanied by toxicity signs in case of CD_3011. There were no changes in serum biochemical parameters except Urea (increased in CDF19 and CD_3011 groups), nor substantial kidney, liver, and spleen injuries. The most impactful for all organs were also CD_3011 and CDF19, causing renal tubule injury and liver blood supply violation. Thus, CDs with a surface enriched with oxygen- and nitrogen-containing functional groups might be toxic after multiple everyday dosing, without, however, significant damages of internal organs in survived animals.

A comparative multi-level toxicity assessment of carbon-based Gd-free dots and Gd-doped nanohybrids from coffee waste: hematology, biochemistry, histopathology and neurobiology study

Here, a comparative toxicity assessment of precursor carbon dots from coffee waste (cofCDs) obtained using green chemistry principles and Gd-doped nanohybrids (cofNHs) was performed using hematological, biochemical, histopathological assays in vivo (CD1 mice, intraperitoneal administration, 14 days), and neurochemical approach in vitro (rat cortex nerve terminals, synaptosomes). Serum biochemistry data revealed similar changes in cofCDs and cofNHs-treated groups, i.e. no changes in liver enzymes' activities and creatinine, but decreased urea and total protein values. Hematology data demonstrated increased lymphocytes and concomitantly decreased granulocytes in both groups, which could evidence inflammatory processes in the organism and was confirmed by liver histopathology; decreased red blood cell-associated parameters and platelet count, and increased mean platelet volume, which might indicate concerns with platelet maturation and was confirmed by spleen histopathology. So, relative safety of both cofCDs and cofNHs for kidney, liver and spleen was shown, whereas there were concerns about platelet maturation and erythropoiesis. In acute neurotoxicity study, cofCDs and cofNHs (0.01 mg/ml) did not affect the extracellular level of L-[14C]glutamate and [3H]GABA in nerve terminal preparations. Therefore, cofNHs demonstrated minimal changes in serum biochemistry and hematology assays, had no acute neurotoxicity signs, and can be considered as perspective biocompatible non-toxic theragnostic agent.

Towards in vivo photomediated delivery of anticancer peptides: Insights from pharmacokinetic and -dynamic data

An in vivo study of a photoswitchable cytotoxic peptide LMB040 has been undertaken on a chemically induced hepatocellular carcinoma model in immunocompetent rats. We analysed the pharmacokinetic profile of the less toxic photoform ("ring-closed" dithienylethene) of the compound in tumors, plasma, and healthy liver. Accordingly, the peptide can reach a tumor concentration sufficiently high to exert a cytotoxic effect upon photoconversion into the more active ("ring-open") photoform. Tissue morphology, histology, redox state of the liver, and hepatic biochemical parameters in blood serum were analysed upon treatment with (i) the less active photoform, (ii) the in vivo light-activated alternative photoform, and (iii) compared with a reference chemotherapeutic 5-fluorouracil. We found that application of the less toxic form followed by a delayed in vivo photoconversion into the more toxic ring-open form of LMB040 led to a higher overall survival of the animals, and signs of enhanced immune response were observed compared to the untreated animals.

Phosphine Oxides (-POMe2) for Medicinal Chemistry: Synthesis, Properties, and Applications

A general practical approach to hetero(aromatic) and aliphatic P(O)Me₂-substituted derivatives is elaborated. The key synthetic step was a [Pd]-mediated C-P coupling of (hetero)aryl bromides/iodides with HP(O)Me₂. The P(O)Me₂ substituent was shown to dramatically increase solubility and decrease lipophilicity of organic compounds. This tactic was used to improve the solubility of the antihypertensive drug prazosin without affecting its biological profile.

Oxa-spirocycles: synthesis, properties and applications

A general approach to a new generation of spirocyclic molecules – oxa-spirocycles – was developed. The key synthetic step was iodocyclization. More than 150 oxa-spirocyclic compounds were prepared. Incorporation of an oxygen atom into the spirocyclic unit dramatically improved water solubility (by up to 40 times) and lowered lipophilicity. More potent oxa-spirocyclic analogues of antihypertensive drug terazosin were synthesized and studied in vivo.

A general practical approach to a new generation of spirocyclic molecules – oxa-spirocycles – is developed.

Suppression of systemic inflammation and signs of acute and chronic cholangitis by multi-kinase inhibitor 1-(4-Cl-benzyl)-3-chloro-4-(CF3-phenylamino)-1H-pyrrole-2,5-dione

An aberrant activity of growth factor receptors followed by excessive cell proliferation plays a significant role in pathogenesis of cholangitis. Therefore, inhibition of these processes could be a fruitful therapeutic strategy. The effects of multi-kinase inhibitor 1-(4-Cl-benzyl)-3-chloro-4-(CF3-phenylamino)-1H-pyrrole-2,5-dione (MI-1) on the hepatic and systemic manifestations of acute and chronic cholangitis in rats were addressed. MI-1 (2.7 mg/kg per day) was applied to male rats that experienced α-naphthylisothiocyanate-induced acute (3 days) or chronic (28 days) cholangitis. Liver autopsy samples, blood serum markers, and leukograms were studied. MI-1 localization in liver cells and its impact on viability of HepG2 (human hepatoma), HL60 (human leukemia), and NIH3T3 (normal murine fibroblasts) cell lines and lymphocytes of human peripheral blood (MTT, DNA fragmentation, DNA comet assays, Propidium Iodide staining) were assessed. Under both acute and chronic cholangitis, MI-1 substantially reduced liver injury, fibrosis, and inflammatory scores (by 46-86%) and normalized blood serum markers and leukograms. Moreover, these effects were preserved after a 28-day recovery period (without any treatment). MI-1 inhibited the HL60, HepG2 cells, and human lymphocytes viability (IC₅₀ 0.6, 9.5 and 8.3 µg/ml, respectively), while NIH3T3 cells were resistant to that. Additionally, HepG2 cells and lymphocytes being incubated with MI-1 demonstrated insignificant pro-apoptotic and pro-necrotic changes and DNA single-strand breaks, suggesting that MI-1 effects in liver might be partly caused by its cytotoxic action towards liver cells and lymphocytes. In conclusion, MI-1 attenuated the systemic inflammation and signs of acute and chronic cholangitis partly through cytotoxicity towards cells of hepatic and leukocytic origin.

Water-Soluble Pristine C60 Fullerene Inhibits Liver Alterations Associated with Hepatocellular Carcinoma in Rat

Excessive production of reactive oxygen species is the main cause of hepatocellular carcinoma (HCC) initiation and progression. Water-soluble pristine C₆₀ fullerene is a powerful and non-toxic antioxidant, therefore, its effect under rat HCC model and its possible mechanisms were aimed to be discovered. Studies on HepG2 cells (human HCC) demonstrated C₆₀ fullerene ability to inhibit cell growth (IC₅₀ = 108.2 μmol), to induce apoptosis, to downregulate glucose-6-phosphate dehydrogenase, to upregulate vimentin and p53 expression and to alter HepG2 redox state. If applied to animals experienced HCC in dose of 0.25 mg/kg per day starting at liver cirrhosis stage, C₆₀ fullerene improved post-treatment survival similar to reference 5-fluorouracil (31 and 30 compared to 17 weeks) and inhibited metastasis unlike the latter. Furthermore, C₆₀ fullerene substantially attenuated liver injury and fibrosis, decreased liver enzymes, and normalized bilirubin and redox markers (elevated by 1.7–7.7 times under HCC). Thus, C₆₀ fullerene ability to inhibit HepG2 cell growth and HCC development and metastasis and to improve animal survival was concluded. C₆₀ fullerene cytostatic action might be realized through apoptosis induction and glucose-6-phosphate dehydrogenase downregulation in addition to its antioxidant activity.

Pyrrole derivatives as potential anti-cancer therapeutics: synthesis, mechanisms of action, safety

Pyrrole derivatives (PDs) chloro-1-(4-chlorobenzyl)-4-((3-(trifluoromethyl)phenyl)amino)-1H-pyrrole-2,5-dione (MI-1) and 5-amino-4-(1,3-benzothyazol-2-yn)-1-(3-methoxyphenyl)-1,2-dihydro-3H-pyrrole-3-one (D1) were synthesised as inhibitors of several protein kinases including EGFR and VEGFR. The aim of the study was to reveal the exact mechanisms of PDs' action EGFR and VEGFR are involved in. We observed, that both PDs could bind with EGFR and VEGFR and form stable complexes. PDs entered into electrostatic interactions with polar groups of phospholipid heads in cell membrane, and the power of interaction depended on the nature of PD radical substituents (greater for MI-1 and smaller for D1). Partial intercalation of MI-1 into the membrane hydrophobic zone also occurred. PDs concentrations induced apoptosis in malignant cells but normal ones had different sensitivity to those. MI-1 and D1 acted like antioxidants in inflamed colonic tissue, as evidenced by reduce of lipid and protein peroxidation products (by 43-67%) and increase of superoxide dismutase activity (by 40 and 58%) with restoring these values to control ones. MI-1 restored reduced haemoglobin and normalised elevated platelets and monocytes in settings of colorectal cancer, whereas D1 normalised only platelets. Thus, MI-1 and D1 could be used as competitive inhibitors of EGFR and VEGFR and antioxidants, which might contribute to realisation of their anti-inflammatory, proapoptotic and antitumor activity.

Water-soluble pristine C60 fullerene attenuates acetaminophen-induced liver injury

Introduction: Oxidative stress has been suggested as the main trigger and pathological mechanism of toxic liver injury. Effects of powerful free radical scavenger С₆₀ fullerene on rat liver injury and liver cells (HepG2 line) were aimed to be discovered.

Methods: Acute liver injury (ALI) was simulated by single acetaminophen (APAP, 1000 mg/kg) administration, on a chronic CLI, by 4 weekly APAP administrations. Pristine C₆₀ fullerene aqueous colloid solution (C₆₀FAS; initial concentration 0.15 mg/mL) was administered per os or intraperitoneally at a dose of 0.5 mg/kg (ALI) or 0.25 mg/kg (CLI) daily for 2 or 28 days, respectively, after first APAP dose. Animals were sacrificed at 24th hour after the last dose. Biochemical markers of blood serum and liver autopsies were analyzed. EGFR expression in HepG2 cells after 48-hour incubation with C₆₀FAS was assessed.

Results: Increase of serum conjugated and unconjugated bilirubin (up to 1.4-3.7 times), ALT (by 31-37%), and AST (by 18%) in non-treated ALI and CLI rats were observed, suggesting the hepatitis (confirmed by histological analysis). Liver morphological state (ALI, CLI), ALT (ALI and CLI), bilirubin (CLI), α-amylase, and creatinine (ALI) were normalized with C₆₀FAS administration in both ways, which may indicate its protective impact on liver. However, unconjugated bilirubin sharply increased in ALI animals receiving C₆₀FAS (up to 12 times compared to control), suggesting the augmentation of bilirubin metabolism. Furthermore, C₆₀FAS inhibited EGFR expression in HepG2 cells in a dose-dependent manner.

Conclusion: C₆₀FAS could partially correct acute and chronic toxic liver injury, however, it could not normalize bilirubin metabolism after acute exposure.