Iron metabolism in the cell as a target in the development of potential antimicrobial and antiviral agents

The search and creation of innovative antimicrobial drugs, acting against resistant and multiresistant strains of bacteria and fungi, are one of the most important tasks of modern bioorganic chemistry and pharmaceuticals. Since iron is essential for the vital activity of almost all organisms, including mammals and bacteria, the proteins involved in its metabolism can serve as potential targets in the development of new promising antimicrobial agents. Such targets include endogenous mammalian biomolecules, heme oxygenases, siderophores, protein 24p3, as well as bacterial heme oxygenases and siderophores. Other proteins that are responsible for the delivery of iron to cells and its balance between bacteria and the host organism also attract certain particular interest. The review summarizes data on the development of inhibitors and inducers (activators) of heme oxygenases, selective for mammals and bacteria, and considers the characteristic features of their mechanisms of action and structure. Based on the reviewed literature data, it was concluded that the use of hemin, the most powerful hemooxygenase inducer, and its derivatives as potential antimicrobial and antiviral agents, in particular against COVID-19 and other dangerous infections, would be a promising approach. In this case, an important role is attributed to the products of hemin degradation formed by heme oxygenases in vitro and in vivo. Certain attention has been paid to the data on the antimicrobial action of iron-free protoporphyrinates, namely complexes with Co, Ga, Zn, Mn, their advantages and disadvantages compared to hemin. Modification of the well-known antibiotic ceftazidime with a siderophore molecule increased its effectiveness against resistant bacteria.

Curtailing virus-induced inflammation in respiratory infections: emerging strategies for therapeutic interventions

Acute respiratory viral infections (ARVI) are the most common illnesses worldwide. In some instances, mild cases of ARVI progress to hyperinflammatory responses, which are damaging to pulmonary tissue and requiring intensive care. Here we summarize available information on preclinical and clinical effects of XC221GI (1-[2-(1-methyl imidazole-4-yl)-ethyl]perhydroazin-2,6-dione), an oral drug with a favorable safety profile that has been tested in animal models of influenza, respiratory syncytial virus, highly pathogenic coronavirus strains and other acute viral upper respiratory infections. XC221GI is capable of controlling IFN-gamma-driven inflammation as it is evident from the suppression of the production of soluble cytokines and chemokines, including IL-6, IL-8, CXCL10, CXCL9 and CXCL11 as well as a decrease in migration of neutrophils into the pulmonary tissue. An excellent safety profile of XC221GI, which is not metabolized by the liver, and its significant anti-inflammatory effects indicate utility of this compound in abating conversion of ambulatory cases of respiratory infections into the cases with aggravated presentation that require hospitalization. This drug is especially useful when rapid molecular assays determining viral species are impractical, or when direct antiviral drugs are not available. Moreover, XC221GI may be combined with direct antiviral drugs to enhance their therapeutic effects.

Improving the synthesis of hemin derivatives and their effect on bacterial biofilms

The emergence of antibiotic-resistant bacterial strains has recently resulted in a large focus on designing new antimicrobial agents, including those based on natural compounds. We have previously synthesized two disubstituted arginine-containing derivatives of hemin (HD) (4) and (5) that demonstrated pronounced antimicrobial activity against planktonic cells in vitro [1, 2]. These HDs are leading and promising for the creation of antibacterial agents on their basis. This research is aimed at improving the synthesis of HDs (4) and (5) to increase their yield, simplify the process and minimize the side reactions, as well as to establish their antimicrobial and destructive effect on biofilms, including those consisting of antibiotic-resistant bacteria. As a result, we were able to increase the yields of the protected dipeptide of ZArg(Z[Formula: see text]SerNH2 (3) and the corresponding HD (4) up to 97 and 93%, respectively, and also to minimize the side reaction of the formation of ornithine-containing HD. For the arginine amide modified HD (5), we have also proposed an improved synthesis scheme. The ability of HD to cause the bacteria death in the composition of formed biofilms, including those consisting of resistant bacteria, was shown. After the effect of HDs on the biofilm at concentrations of 80 and 100 [Formula: see text]g/ml, the CFU decrease was 3–5/ml. The fluorescent microscopy confirmed the bacteria mortality in the biofilm. Electron microscopy showed structural damage (fragmentation) of the formed bacterial biofilm under the effect of HDs.

Molecular basis of COVID-19 pathogenesis

The review summarizes the publications, available at the time it was written, addressing the chemical and biological processes that occur in the human body upon exposure to coronaviruses, in particular SARS-CoV-2. The mechanisms of viral particle entry into the cell, viral replication and impact on the immune system and on oxygen transport system are considered. The causes behind complications of the viral infection, such as vasculitis, thrombosis, cytokine storm and lung fibrosis, are discussed. The latest research in the field of small molecule medications to counteract the virus is surveyed. Molecular targets and possible vectors to exploit them are considered. The review is primarily written for specialists who want to understand the chains of activation, replication, action and inhibition of SARS-CoV-2. Due to the short period of such studies, the data on complexes of small molecule compounds with possible protein targets are not numerous, but they will be useful in the search and synthesis of new potentially effective drugs.

The bibliography includes 144 references.

A Novel Oral Glutarimide Derivative XC8 Suppresses Sephadex-Induced Lung Inflammation in Rats and Ovalbumin-induced Acute and Chronic Asthma in Guinea Pigs

BACKGROUND

Corticosteroids are the preferred option to treat asthma, however, they possess serious side effects and are inefficient in 10% of patients. Thus, new therapeutic approaches for asthma treatment are required.

OBJECTIVE

To study the efficacy of a novel glutarimide derivative XC8 in a Sephadex-induced lung inflammation in rats as well as in acute and chronic ovalbumin-induced allergic asthma in guinea pigs.

METHOD

Rats were treated with 0.18-18 mg/kg of XC8 intragastrically 4 times (24 h and 1 h prior to and 24 h and 45 h after endotracheal administration of Sephadex). The number of inflammatory cells in bronchoalveaolar lavages (BAL) was determined. Guinea pigs were treated with 0.045 -1.4 mg/kg (acute asthma) or with 1.4 and 7.0 mg/kg of XC8 (chronic asthma) intragastrically following the sensitization with ovalbumin and during aerosol challenge. Lung inflammation, numbers of eosinophils (BAL and lung tissue), goblet cells, degranulating mast cells and specific airway resistance (sRAW) were determined. The comparator steroid drug budesonide (0.5 mg/kg for rats and 0.16 mg/kg for guinea pigs) was administered by inhalation.

RESULTS

XC8 reduced influx of eosinophils into BAL in Sephadex-induced lung inflammation model in rats (by 2.6-6.4 times). Treatment of acute asthma in guinea pigs significantly reduced eosinophils in guinea pigs in BAL (from 55% to 30%-39% of the total cell count) and goblet cells in lung tissue. In a model of acute and chronic asthma, XC8 reduced significantly the number of eosinophils and degranulating mast cells in the lung tissue. Treatment with XC8 but not with budesonide decreased the specific airway resistance in acute and chronic asthma model up to the level of naive animals.

CONCLUSION

XC8 induced a profound anti-inflammatory effect by reducing eosinophils in BAL and eosinophils and degranulating mast cell numbers in the airway tissue. The anti-asthmatic effect of XC8 is comparable to that of budesonide. Moreover, in contrast to budesonide, XC8 was capable to reduce goblet cells and airway resistance.

The effect of elongation of a peptide substituent with ArgSer motif on the antimicrobial properties of hemin derivatives

The natural metalloporphyrin hemin possesses a number of properties that determine its attractiveness as a basis for creating potential medicines. The development of research in this area is restrained by hemin’s pronounced toxicity, mainly in relation to normal red blood cells, and also by its water insolubility. We previously synthesized amino acid and peptide hemin derivatives with sufficient water solubility and in some cases high antimicrobial (antibacterial and antifungal) potency [1, 2]. In order to establish the relationship between structure and function, this paper studies the peptide substituent in hemin derivatives (HD) elongated by multiplying the -ArgSer- motif and its effect on the biological and physicochemical properties of their aqueous solutions. A nonlinear nonmonotonic dependence of their physicochemical properties and biological potency on the HD concentration and the length of peptide substituent was revealed based on calculations of hydrophilic properties of substituents in HD and a study by electron and laser correlation spectroscopy of their properties in aqueous solutions.

Amino acid and peptide hemin derivatives as new promising virucidal agents

We synthesized a series of hemin derivatives (HDs) substituted by residues of amino acids and peptides at either one or two propionic-acid residues, and studied the virucidal activity of the compounds obtained against herpes simplex virus. Compounds 6,7-bis-(methyl ester N0L-seryl)-protohemin (IX) (2) and 6,7-bis-[methyl ester N0-L-arginyl)-protohemin (IX) (6) shown the highest virucidal activity. We also investigated the interaction between HDs and lipid-membrane components as a possible mechanism of virucidal action. A model system including Clark's electrode and a micellar solution of methyl linoleate was used to quantitatively assess the capability of HDs to catalyze the oxidation of polyunsaturated fatty acids as components of lipid membranes. Another model system including liposomes that consisted of dioleoylphosphatydylcholine and was loaded with the fluorescent dye carboxyfluorescein was employed to examine the effect of HDs on lipid-membrane permeability. The kinetics and efficacy of increasing liposome-membrane permeability on exposure to HDs appeared to depend on the nature of the substituents in the HDs. The findings are strongly suggestive of the presence of two different modes of interaction between an HD and the lipid membrane, i.e. oxidative and non-oxidative mechanisms possibly underlie the virucidal action of HDs.

Mechanisms of protective effect of Dicarbamin on the blood system in cytostatic treatment

The effect of Dicarbamin preparation on hemopoiesis suppressed with cyclophosphamide was studied in animal experiments. It was shown that Dicarbamin produced a protective effect on granulocytic hemopoietic steam. This property of the preparation is determined by both protection of immature granulocytic cells at early terms after cytostatic treatment and more active maturation of neutrophils in the bone marrow due to enhanced secretion of humoral factors by elements of hemopoietic environment at late terms of the experiment.

[Study of Ingavirin antiviral activity against Mexican pandemic influenza virus A/H1N1/2009 in vitro and in vivo]

High in vitro and in vivo efficacy of Ingavirin against the Mexican pandemic influenza virus A/H1N1/2009, strains A/California/04/2009 (H1N1) and A/California/07/2009 (H1N1) vs. the reference drug Arbidol was studied and verified when used therapeutically and prophylactically.

Efficacy of metmyoglobin and hemin as a catalyst of lipid peroxidation determined by using a new testing system

A new quantitative approach to investigate the capability of iron heme complexes (HEM), metmyoglobin and hemin, to catalyze lipid peroxidation was elaborated. The oxidation of methyl linoleate in micellar solutions was used as a testing model. The key point was the determination of the rate of free radical generation, RIN, calculated from the rate of oxygen consumption. The HEM catalytic activity was characterized by two independent parameters: by reactivity and by its resistance to degradation. Both parameters were found to be pH-dependent. The reactivity was expressed as the effective rate constant for the reaction of HEM with lipid hydroperoxide. The resistance to degradation was characterized by the rate of the decrease in RIN with time and also by the regeneration coefficient, which shows how many active free radicals can be generated by one molecule of HEM. Both Hemin and metMB were found to be very effective catalysts even at nanomolar concentrations. The effective regeneration of active forms of HEM was observed. The catalytic activity of HEM was rapidly reduced with time. The kinetic scheme of the process under consideration was suggested, and this was applied for kinetic computer simulations.