Evaluation of Acute and Sub-Acute Toxicity, Oxidative Stress and Molecular Docking of Two Nitrofuranyl Amides as Promising Anti-Tuberculosis Agents.

Tuberculosis (TB) remains a widespread infectious disease and one of the top 10 causes of death worldwide. Nevertheless, despite significant advances in the development of new drugs against tuberculosis, many therapies and preventive measures do not lead to the expected favorable health results for various reasons. The aim of this study was to evaluate the acute and sub-acute toxicity and oxidative stress of two selected nitrofuranyl amides with high in vitro antimycobacterial activity. In addition, molecular docking studies were performed on both compounds to elucidate the possibilities for further development of new anti-tuberculosis candidates with improved efficacy, selectivity, and pharmacological parameters. Acute toxicity tests showed that no changes were observed in the skin, coat, eyes, mucous membranes, secretions, and vegetative activity in mice. The histological findings include features consistent with normal histological architecture without being associated with concomitant pathological conditions. The observed oxidative stress markers indicated that the studied compounds disturbed the oxidative balance in the mouse liver. Based on the molecular docking, compound DO-190 showed preferable binding energies compared to DO-209 in three out of four targets, while both compounds showed promising protein-ligand interactions. Thus, both studied compounds displayed promising activity with low toxicity and can be considered for further evaluation and/or lead optimization.

Insight into pathogenomics and phylogeography of hypervirulent and highly-lethal Mycobacterium tuberculosis strain cluster.

BACKGROUND: . The Mycobacterium tuberculosis Beijing genotype is globally spread lineage with important medical properties that however vary among its subtypes. M. tuberculosis Beijing 14717-15-cluster was recently discovered as both multidrug-resistant, hypervirulent, and highly-lethal strain circulating in the Far Eastern region of Russia. Here, we aimed to analyze its pathogenomic features and phylogeographic pattern. RESULTS: . The study collection included M. tuberculosis DNA collected between 1996 and 2020 in different world regions. The bacterial DNA was subjected to genotyping and whole genome sequencing followed by bioinformatics and phylogenetic analysis. The PCR-based assay to detect specific SNPs of the Beijing 14717-15-cluster was developed and used for its screening in the global collections. Phylogenomic and phylogeographic analysis confirmed endemic prevalence of the Beijing 14717-15-cluster in the Asian part of Russia, and distant common ancestor with isolates from Korea (> 115 SNPs). The Beijing 14717-15-cluster isolates had two common resistance mutations RpsL Lys88Arg and KatG Ser315Thr and belonged to spoligotype SIT269. The Russian isolates of this cluster were from the Asian Russia while 4 isolates were from the Netherlands and Spain. The cluster-specific SNPs that significantly affect the protein function were identified in silico in genes within different categories (lipid metabolism, regulatory proteins, intermediary metabolism and respiration, PE/PPE, cell wall and cell processes). CONCLUSIONS: . We developed a simple method based on real-time PCR to detect clinically significant MDR and hypervirulent Beijing 14717-15-cluster. Most of the identified cluster-specific mutations were previously unreported and could potentially be associated with increased pathogenic properties of this hypervirulent M. tuberculosis strain. Further experimental study to assess the pathobiological role of these mutations is warranted.

Recent Advances in Anti-Tuberculosis Drug Discovery Based on Hydrazide-Hydrazone and Thiadiazole Derivatives Targeting InhA.

Tuberculosis is an extremely serious problem of global public health. Its incidence is worsened by the presence of multidrug-resistant (MDR) strains of Mycobacterium tuberculosis. More serious forms of drug resistance have been observed in recent years. Therefore, the discovery and/or synthesis of new potent and less toxic anti-tubercular compounds is very critical, especially having in mind the consequences and the delays in treatment caused by the COVID-19 pandemic. Enoyl-acyl carrier protein reductase (InhA) is an important enzyme involved in the biosynthesis of mycolic acid, a major component of the M. tuberculosis cell wall. At the same time, it is a key enzyme in the development of drug resistance, making it an important target for the discovery of new antimycobacterial agents. Many different chemical scaffolds, including hydrazide hydrazones and thiadiazoles, have been evaluated for their InhA inhibitory activity. The aim of this review is to evaluate recently described hydrazide-hydrazone- and thiadiazole-containing derivatives that inhibit InhA activity, resulting in antimycobacterial effects. In addition, a brief review of the mechanisms of action of currently available anti-tuberculosis drugs is provided, including recently approved agents and molecules in clinical trials.

First Insight into Diversity of Minisatellite Loci in Mycobacterium bovis/M. caprae in Bulgaria.

The aim of this study was to assess the diversity of minisatellite VNTR loci in Mycobacterium bovis/M. caprae isolates in Bulgaria and view their position within global M. bovis diversity. Forty-three M. bovis/M. caprae isolates from cattle in different farms in Bulgaria were collected in 2015-2021 and typed in 13 VNTR loci. The M. bovis and M. caprae branches were clearly separated on the VNTR phylogenetic tree. The larger and more geographically dispersed M. caprae group was more diverse than M. bovis group was (HGI 0.67 vs. 0.60). Overall, six clusters were identified (from 2 to 19 isolates) and nine orphans (all loci-based HGI 0.79). Locus QUB3232 was the most discriminatory one (HGI 0.64). MIRU4 and MIRU40 were monomorphic, and MIRU26 was almost monomorphic. Four loci (ETRA, ETRB, Mtub21, and MIRU16) discriminated only between M. bovis and M. caprae. The comparison with published VNTR datasets from 11 countries showed both overall heterogeneity between the settings and predominantly local evolution of the clonal complexes. To conclude, six loci may be recommended for primary genotyping of M. bovis/M. caprae isolates in Bulgaria: ETRC, QUB11b, QUB11a, QUB26, QUB3232, and MIRU10 (HGI 0.77). VNTR typing based on a limited number of loci appears to be useful for primary bTB surveillance.

Molecular Insight into Mycobacterium tuberculosis Resistance to Nitrofuranyl Amides Gained through Metagenomics-like Analysis of Spontaneous Mutants.

We performed synthesis of new nitrofuranyl amides and investigated their anti-TB activity and primary genetic response of mycobacteria through whole-genome sequencing (WGS) of spontaneous resistant mutants. The in vitro activity was assessed on reference strain Mycobacterium tuberculosis H37Rv. The most active compound 11 was used for in vitro selection of spontaneous resistant mutants. The same mutations in six genes were detected in bacterial cultures grown under increased concentrations of 11 (2×, 4×, 8× MIC). The mutant positions were presented as mixed wild type and mutant alleles while increasing the concentration of the compound led to the semi-proportional and significant increase in mutant alleles. The identified genes belong to different categories and pathways. Some of them were previously reported as mediating drug resistance or drug tolerance, and counteracting oxidative and nitrosative stress, in particular: Rv0224c, fbiC, iniA, and Rv1592c. Gene-set interaction analysis revealed a certain weak interaction for gene pairs Rv1592-Rv1639c and Rv1592-Rv0224c. To conclude, this study experimentally demonstrated a multifaceted primary genetic response of M. tuberculosis to the action of nitrofurans. All three 11-treated subcultures independently presented the same six SNPs, which suggests their non-random occurrence and likely causative relationship between compound action and possible resistance mechanism.

Development of New Antimycobacterial Sulfonyl Hydrazones and 4-Methyl-1,2,3-thiadiazole-Based Hydrazone Derivatives.

Fifteen 4-methyl-1,2,3-thiadiazole-based hydrazone derivatives 3a-d and sulfonyl hydrazones 5a-k were synthesized. They were characterized by 1H-NMR, 13C NMR, and HRMS. Mycobacterium tuberculosis strain H37Rv was used to assess their antimycobacterial activity. All compounds demonstrated significant minimum inhibitory concentrations (MIC) from 0.07 to 0.32 µM, comparable to those of isoniazid. The cytotoxicity was evaluated using the standard MTT-dye reduction test against human embryonic kidney cells HEK-293T and mouse fibroblast cell line CCL-1. 4-Hydroxy-3-methoxyphenyl substituted 1,2,3-thiadiazole-based hydrazone derivative 3d demonstrated the highest antimycobacterial activity (MIC = 0.0730 µM) and minimal associated cytotoxicity against two normal cell lines (selectivity index SI = 3516, HEK-293, and SI = 2979, CCL-1). The next in order were sulfonyl hydrazones 5g and 5k with MIC 0.0763 and 0.0716 µM, respectively, which demonstrated comparable minimal cytotoxicity. All compounds were subjected to ADME/Tox computational predictions, which showed that all compounds corresponded to Lipinski's Ro5, and none were at risk of toxicity. The suitable scores of molecular docking performed on two crystallographic structures of enoyl-ACP reductase (InhA) provide promising insight into possible interaction with the InhA receptor. The 4-methyl-1,2,3-thiadiazole-based hydrazone derivatives and sulfonyl hydrazones proved to be new classes of lead compounds having the potential of novel candidate antituberculosis drugs.

Mycobacterium bovis and M. caprae in Bulgaria: insight into transmission and phylogeography gained through whole-genome sequencing.

BACKGROUND: This study aimed to characterize recent Mycobacterium bovis/M. caprae isolates from Bulgaria by whole-genome sequencing (WGS) to gain a first insight into their molecular diversity, transmission, and position within the global phylogeography of this important zoonotic species. RESULTS: The isolates were obtained from cattle in diverse locations of Bulgaria in 2015-2020 and were identified by microbiological and PCR assays. WGS data were used for phylogenetic analysis that also included M. bovis global dataset. Thirty-seven M. bovis/caprae isolates from Bulgaria were studied and 34 of them were SNP genotyped. The isolates were subdivided into 3 major phylogenetic groups. Type Mbovis-13 (Eu2 complex [western Europe and northern Africa]) included one isolate. Mbovis-37 type included 5 isolates outside of known clonal complexes. The Bulgarian M. caprae isolates formed a sub-group within the Mcaprae-27B cluster which also included 22 M. caprae isolates from Poland, Spain, Germany, and the Republic of Congo. The Bulgarian M. caprae isolates share their latest common ancestors with Spanish isolates. The Mbovis-37 group shares a distant common ancestor (pairwise distance 22-29 SNPs) with an isolate from Poland but was very distant (> 200 SNPs) from the rest of the tree. The Mbovis-13 group shares a common ancestor with two human isolates from Germany. Phylogeographically, both M. bovis clades had limited circulation in northeastern Bulgaria while the majority of the studied isolates (M. caprae) were from central and western provinces. A phylogenetic network-based analysis demonstrated that 11 Bulgarian isolates were separated by 1 to 6 SNPs within four clusters, mostly forming pairs of isolates. CONCLUSION: The obtained WGS analysis positioned the Bulgarian isolates within the global phylogeography of M. bovis/M. caprae. Hypothetically, the observed phylogenetic diversity may not have resulted from livestock trade routes, but instead may reflect the deeply rooted M. bovis/M. caprae phylogeography of Europe. A high level of genetic divergence between the majority of the studied isolates suggests limited active transmission of bTB in Bulgaria during the survey period. At the same time, a possibility of the endemic presence of circulating bTB strains in the form of the latent persistent disease cannot be ruled out.

Antimicrobial Triterpenoids and Ingol Diterpenes from Propolis of Semi-Arid Region of Morocco.

The chemical composition and antimicrobial activity of propolis from a semi-arid region of Morocco were investigated. Fifteen compounds, including triterpenoids (1, 2, 7-12), macrocyclic diterpenes of ingol type (3-6) and aromatic derivatives (13-15), were isolated by various chromatographic methods. Their structures were elucidated by a combination of spectroscopic and chiroptical methods. Compounds 1 and 3 are new natural compounds, and 2, 4-6, and 9-11 are newly isolated from propolis. Moreover, the full nuclear magnetic resonance (NMR) assignments of three of the known compounds (2, 4 and 5) were reported for the first time. Most of the compounds tested, especially the diterpenes 3, 4, and 6, exhibited very good activity against different strains of bacteria and fungi. Compound 3 showed the strongest activity with minimum inhibitory concentrations (MICs) in the range of 4-64 µg/mL. The combination of isolated triterpenoids and ingol diterpenes was found to be characteristic for Euphorbia spp., and Euphorbia officinarum subsp. echinus could be suggested as a probable and new plant source of propolis.

In Vivo Toxicity, Redox-Modulating Capacity and Intestinal Permeability of Novel Aroylhydrazone Derivatives as Anti-Tuberculosis Agents.

The emergence and spread of Mycobacterium tuberculosis strains resistant to many or all anti-tuberculosis (TB) drugs require the development of new compounds both efficient and with minimal side effects. Structure-activity-toxicity relationships of such novel, structurally diverse compounds must be thoroughly elucidated before further development. Here, we present the aroylhydrazone compounds (3a and 3b) regarding their: (i) acute and subacute toxicity in mice; (ii) redox-modulating in vivo and in vitro capacity; (iii) pathomorphology in the liver, kidney, and small intestine tissue specimens; and (iv) intestinal permeability. The acute toxicity test showed that the two investigated compounds exhibited low toxicity by oral and intraperitoneal administration. Changes in behavior, food amount, and water intake were not observed during 14 days of the oral administration at two doses of 1/10 and 1/20 of the LD50. The histological examination of the different tissue specimens did not show toxic changes. The in vitro antioxidant assays confirmed the ex vivo results. High gastrointestinal tract permeability at all tested pH values were demonstrated for both compounds. To conclude, both compounds 3a and 3b are highly permeable with low toxicity and can be considered for further evaluation and/or lead optimization.

Rose Flowers-A Delicate Perfume or a Natural Healer?

Plants from the Rosacea family are rich in natural molecules with beneficial biological properties, and they are widely appreciated and used in the food industry, perfumery, and cosmetics. In this review, we are considering Rosa damascena Mill., Rosa alba L., Rosa centifolia L., and Rosa gallica L. as raw materials important for producing commercial products, analyzing and comparing the main biological activities of their essential oils, hydrolates, and extracts. A literature search was performed to find materials describing (i) botanical characteristics; (ii) the phytochemical profile; and (iii) biological properties of the essential oil sand extracts of these so called "old roses" that are cultivated in Bulgaria, Turkey, India, and the Middle East. The information used is from databases PubMed, Science Direct, and Google Scholar. Roses have beneficial healing properties due to their richness of beneficial components, the secondary metabolites as flavonoids (e.g., flavones, flavonols, anthocyanins), fragrant components (essential oils, e.g., monoterpenes, sesquiterpenes), and hydrolysable and condensed tannins. Rose essential oils and extracts with their therapeutic properties-as respiratory antiseptics, anti-inflammatories, mucolytics, expectorants, decongestants, and antioxidants-are able to act as symptomatic prophylactics and drugs, and in this way alleviate dramatic sufferings during severe diseases.

First insight into phylogeography of Mycobacterium bovis and M. caprae from cattle in Bulgaria.

Bovine tuberculosis (bTB) represents a significant economic burden to the agriculture. In spite of decades of the control program, Mycobacterium bovis infection levels in cattle in Bulgaria continued to rise over recent years. In order to gain a better understanding of the M. bovis diversity, we used spoligotyping for strain differentiation and the data were compared to the international databases Mbovis.org and SITVIT2 for shared type and clade assignment. Study sample included 30 M. tuberculosis complex isolates from cattle originating from different regions of Bulgaria. The isolates were subdivided by spoligotyping into 4 spoligotypes: 2 types shared by 20 and 8 isolates and 2 singletons. SITVIT2-defined types SIT645 and SIT647 belonged to the common and classical bovine ecotype M. bovis (9 isolates) while types SIT120 and SIT339 belonged to the M. caprae ecotype (21 isolates). A certain phylogeographic gradient of the spoligotypes and clades at the within-country level was observed: M. caprae was prevalent in the central/southwestern, while classical M. bovis in the northeastern Bulgaria. Whereas all four types have global or European circulation, neither was described in the neighboring Balkan countries. M. caprae isolates identified in this study mostly belong to the Central/Eastern European cluster. In summary, this study provided a first insight into phylogeography of M. bovis in Bulgaria and described, for the first time, M. caprae as an important infectious agent of bTB in this country.

Hypepontine, a new quaternary alkaloid with antimicrobial properties.

New isoquinoline alkaloid hypepontine (1) together with a five known compounds, were identified in Hypecoum ponticum Velen, the partial synonym of Hypecoum procumbens L. The structure of the new substance was elucidated based on spectroscopic evidence. The tertiary and quaternary alkaloid mixtures as well as the isolated alkaloids were evaluated for their antibacterial and antifungal activity. The result revealed that the crude alkaloid mixture containing quaternary isoquinoline alkaloids showed potent antifungal and antibacterial activity.

New cycloartane triterpenes from bioactive extract of propolis from Pitcairn Island.

Dichloromethane extract of propolis (DCME) originating from Pitcairn Island demonstrated potent cytotoxicity against triple-negative MDA-MB-231 human breast carcinoma cells. The results from MTT assay showed that DCME inhibits the growth of the cancer cells in a dose- and time-dependent manner and upon the cell growth inhibition propolis extract provoked apoptotic changes in the cell nuclei. A detailed chemical investigation of DCME led to the isolation of four new cycloartane triterpenes (1-4), along with 17 known compounds (5-21). The structures of the new compounds were elucidated by means of extensive analysis of their spectroscopic data and comparison with those reported for their analogues. In vitro antimicrobial activity of new compounds (1-4) along with the DCME against four human pathogens was evaluated. All tested constituents except compound 2 were highly active against Escherichia coli with MIC 64 µg/ml. Compound 1 exhibited high antifungal activity against Candida albicans with potency close to that of the positive control (amphotericin B). The DCME showed very good antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans. This is the first study on propolis from Pitcairn Island.

Xanthates: Metabolism by Flavoprotein-Containing Monooxygenases and Antimycobacterial Activity.

Ethionamide (ETH) plays a central role in the treatment of tuberculosis in patients resistant to the first-line drugs. The ETH, thioamide, and thiourea class of antituberculosis agents are prodrugs that are oxidatively converted to their active S-oxides by the mycobacterial flavin-dependent monooxygenase (EtaA) of Mycobacterium tuberculosis, thus initiating the chain of reactions that result in inhibition of mycolic acid biosynthesis and cell lysis. As part of a search for new lead candidates, we report here that several xanthates are oxidized by purified EtaA to S-oxide metabolites (perxanthates), which are implicated in the antimycobacterial activity of these compounds. This process, which is analogous to that responsible for activation of ETH, is also catalyzed by human flavoprotein monooxygenase 3. EtaA was not inhibited in a time-dependent manner during the reaction. Xanthates with longer alkyl chains were oxidized more efficiently. EtaA oxidized octyl-xanthate (Km = 5 µM; Vmax = 1.023 nmolP/min; kcat = 5.2 molP/min/molE) more efficiently than ETH (194 µM; 1.46 nmolP/min; 7.73 nmolP/min/molE, respectively). Furthermore, the in vitro antimycobacterial activity of four xanthates against M. tuberculosis H37Hv was higher (minimum inhibitory concentration of around 1 µM) than that of ETH (12 µM).

Synthetic piperine amide analogs with antimycobacterial activity.

Piperine amide analogs are synthesized by replacement of the piperidine moiety with different types of cyclic amines, including adamantyl and monoterpene-derived fragments. The compounds are screened for activity against Mycobacterium tuberculosis H37Rv. The most potent compounds are the 1-adamantyl and the monoterpene-derived hybrids, which combine nanomolar antimycobacterial activity with low cytotoxicity against human cells. The presence of quaternary carbon atom as main structural requirement for anti-TB activity is pointed out by a QSAR study. The most promising compound is the (+)-isopinocampheylamine-derived amide which is characterized with selectivity index of 1387.8.

Synthesis, antimycobacterial activity and docking study of 2-aroyl-[1]benzopyrano[4,3-c]pyrazol-4(1H)-one derivatives and related hydrazide-hydrazones.

A new convenient method for preparation of 2-aroyl-[1]benzopyrano[4,3-c]pyrazol-4(1H)-one derivatives 5b-g and coumarin containing hydrazide-hydrazone analogues 4a-e was presented. The antimycobacterial activity against reference strain Mycobacterium tuberculosis H37Rv and cytotoxicity against the human embryonic kidney cell line HEK-293 were tested in vitro. All compounds demonstrated significant minimum inhibitory concentrations (MIC) ranging 0.28-1.69µM, which were comparable to those of isoniazid. The cytotoxicity (IC50>200µM) to the "normal cell" model HEK-293T exhibited by 2-aroyl-[1]benzopyrano[4,3-c]pyrazol-4(1H)-one derivatives 5b-e, was noticeably milder compared to that of their hydrazone analogues 4a-e (IC50 33-403µM). Molecular docking studies on compounds 4a-e and 5b-g were also carried out to investigate their binding to the 2-trans-enoyl-ACP reductase (InhA) enzyme involved in M. tuberculosis cell wall biogenesis. The binding model suggested one or more hydrogen bonding and/or arene-H or arene-arene interactions between hydrazones or pyrazole-fused coumarin derivatives and InhA enzyme for all synthesized compounds.

Antimycobacterial activity of novel hydrazide-hydrazone derivatives with 2H-chromene and coumarin scaffold.

This study reports the synthesis of new 2H-chromene or coumarin based acylhydrazones, which were evaluated for their in vitro antimycobacterial activity against reference strain Mycobacterium tuberculosis H37Rv and compared to the first-line antituberculosis drugs, isoniazid (INH) and ethambutol (EMB). The most active compounds 7m (MIC 0.13µM), 7o (MIC 0.15µM) and 7k (MIC 0.17µM) demonstrated antimycobacterial activity at submicromolar concentration level and remarkably minimal associated cytotoxicity in the human embryonic kidney cell line HEK-293T. Structure-activity relationship for this class of compounds has been established.

Latin-American-Mediterranean lineage of Mycobacterium tuberculosis: Human traces across pathogen's phylogeography.

Currently, Mycobacterium tuberculosis isolates of Latin-American Mediterranean (LAM) family may be detected far beyond the geographic areas that coined its name 15years ago. Here, we established the framework phylogeny of this geographically intriguing and pathobiologically important mycobacterial lineage and hypothesized how human demographics and migration influenced its phylogeography. Phylogenetic analysis of LAM isolates from all continents based on 24 variable number of tandem repeats (VNTR) loci and other markers identified three global sublineages with certain geographic affinities and defined by large deletions RD115, RD174, and by spoligotype SIT33. One minor sublineage (spoligotype SIT388) appears endemic in Japan. One-locus VNTR signatures were established for sublineages and served for their search in published literature and geographic mapping. We suggest that the LAM family originated in the Western Mediterranean region. The most widespread RD115 sublineage seems the most ancient and encompasses genetically and geographically distant branches, including extremely drug resistant KZN in South Africa and LAM-RUS recently widespread across Northern Eurasia. The RD174 sublineage likely started its active spread in Brazil; its earlier branch is relatively dominated by isolates from South America and the derived one is dominated by Portuguese and South/Southeastern African isolates. The relatively most recent SIT33-sublineage is marked with enigmatic gaps and peaks across the Americas and includes South African clade F11/RD761, which likely emerged within the SIT33 subpopulation after its arrival to Africa. In addition to SIT388-sublineage, other deeply rooted, endemic LAM sublineages may exist that remain to be discovered. As a general conclusion, human mass migration appears to be the major factor that shaped the M. tuberculosis phylogeography over large time-spans.

Design, Synthesis, and Antimycobacterial Activity of Novel Theophylline-7-Acetic Acid Derivatives With Amino Acid Moieties.

The theophylline-7-acetic acid (7-TAA) scaffold is a promising novel lead compound for antimycobacterial activity. Here, we derive a model for antitubercular activity prediction based on 14 7-TAA derivatives with amino acid moieties and their methyl esters. The model is applied to a combinatorial library, consisting of 40 amino acid and methyl ester derivatives of 7-TAA. The best three predicted compounds are synthesized and tested against Mycobacterium tuberculosis H37Rv. All of them are stable, non-toxic against human cells and show antimycobacterial activity in the nanomolar range being 60 times more active than ethambutol.