The synthesis, structure and activity evaluation of pyrogallol and catechol derivatives as Helicobacter pylori urease inhibitors

Antibacterial activity of a plant natural poly-phenol against zoonotic Streptococcus suis

The increasing emergence and dissemination of multi-drugs resistant bacterial pathogens accelerate the desires for novel antimicrobials. Natural products are great resources for the discovery of antimicrobial compound. In this study, pyrogallol was screened from 25 poly-phenols for its antibacterial activity against multi-drugs resistant Streptococcus suis (S. suis), particularly, pyrogallol had synergistic antimicrobial effect with doxycycline, sulfafurazole and clindamycin, respectively. Pyrogallol showed significant inhibitory effects on bacterial biofilm formation, and caused cell wall and cell membrane injury to S. suis. Furthermore, mechanistic studies demonstrated that pyrogallol might interact with peptidoglycan and decreased the expression of virulence and growth-related genes, such as ftsZ, stK, sly, fbps and luxS. In cell model, pyrogallol protected Nptr cells from S. suis-mediated cell damage. Finally, in mouse model, the pyrogallol and antibiotics combination groups with dosage given in the half could be as effective as antibiotics groups. In summary, these results demonstrated the capacity of pyrogallol serving as a candidate for novel antibiotic alternative and antibiotic adjuvant to circumvent the antibiotics resistance and reduced antibiotic consumption.

Urease inhibitors for the treatment of H. pylori

INTRODUCTION

Helicobacter pylori infects almost half of the World population. Although many infected people are symptom free, the microorganism can still cause a variety of gastrointestinal disorders and gastric adenocarcinoma. It is considered a priority pathogen for the development of new antibiotics by the World Health Organisation (WHO). Many virulence factors of H. pylori have been described. This paper will on H. pylori Urease (HPU).

AREA COVERED

This paper will discuss the (patho)physiology and structure of HPU. In addition, urease inhibitors with known activity against the HPU or inhibitors that show H. pylori growth inhibition will be discussed.

EXPERT OPINION

Increase in selectivity, affinity and potency of HPU inhibitors can be achieved by the design of compounds that interact with distinct regions within the enzyme active site. Especially, covalent interactions seem promising as they clearly effect the dose requirement of the drug candidate.

Unrivalled Insight into Possible Biopharmaceutical Application of Justicia vahlii Roth. (Acanthaceae): Chemodiversity, In Vitro Bioactivities, and Computational Analysis

Justicia vahliiRoth. is an important wild medicinal food plant traditionally used for treating inflammation and various common ailments. This study investigated the chemical composition, antioxidant, enzyme inhibition and toxicity profiles of n-hexane (nHEJv) and chloroform (CEJv) extracts of J. vahlii. Moreover, the effect of the extracts was evaluated on CCl4 induced liver injury. The total phenolic and flavonoid contents were present in both extracts in significant amount. The UPLC-Q-TOF-MS and GC-MS profiling of CEJv tentatively identified several important phytocompounds. The CEJv extract was comparatively more active for antioxidant activity and α-amylase inhibition, whereas the nHEJv extract presented higher inhibition potential against urease, tyrosinase, and α-glucosidase enzymes. Similarly, the in-silicostudy of four major compounds, i. e., 1-acetoxypinoresinol, 3-hydroxysebacic acid, nortrachelogenin, and viscidulin-III have shown a good docking score against the clinically significant enzymes. The acute oral toxicity and brine shrimp lethality assaysrevealed the extracts as non-toxic. The CCl4 treated animals showed a geared depletion of various antioxidant enzymes which were significantly reversed with the treatment of the extracts. Overall, the study's findings revealed J. vahliiwith antioxidant mediated hepatoprotective and enzyme inhibition potential and warrant further research on isolation of the bioactive compounds.

Pyrogallol experimentally and theoretically suppressed advanced glycation end products (AGEs) formation, as one of the mechanisms involved in the chronic complications of the diabetes

This study aimed to explore the inhibitory effect of pyrogallol on AGE formation in the bovine serum albumin (BSA)/glucose system for 21 days at 37 °C. The AGEs formation was measured in terms of Amadori products, total AGEs, argpyrimidine, and pentosidine. Molecular docking was used to investigate the interaction between pyrogallol and BSA. According to the results, in the presence of pyrogallol, the formation of pentosidine and argpyrimidine AGEs decreased. The molecular interaction studies demonstrated that pyrogallol has a high affinity towards arginine residues of albumin. Finally, results proved pyrogallol is a vigorous antiglycation compound and fruitful for AGE inhibition.

Unveiling Novel Urease Inhibitors for Helicobacter pylori: A Multi-Methodological Approach from Virtual Screening and ADME to Molecular Dynamics Simulations

Helicobacter pylori (Hp) infections pose a global health challenge demanding innovative therapeutic strategies by which to eradicate them. Urease, a key Hp virulence factor hydrolyzes urea, facilitating bacterial survival in the acidic gastric environment. In this study, a multi-methodological approach combining pharmacophore- and structure-based virtual screening, molecular dynamics simulations, and MM-GBSA calculations was employed to identify novel inhibitors for Hp urease (HpU). A refined dataset of 8,271,505 small molecules from the ZINC15 database underwent pharmacokinetic and physicochemical filtering, resulting in 16% of compounds for pharmacophore-based virtual screening. Molecular docking simulations were performed in successive stages, utilizing HTVS, SP, and XP algorithms. Subsequent energetic re-scoring with MM-GBSA identified promising candidates interacting with distinct urease variants. Lys219, a residue critical for urea catalysis at the urease binding site, can manifest in two forms, neutral (LYN) or carbamylated (KCX). Notably, the evaluated molecules demonstrated different interaction and energetic patterns in both protein variants. Further evaluation through ADMET predictions highlighted compounds with favorable pharmacological profiles, leading to the identification of 15 candidates. Molecular dynamics simulations revealed comparable structural stability to the control DJM, with candidates 5, 8 and 12 (CA5, CA8, and CA12, respectively) exhibiting the lowest binding free energies. These inhibitors suggest a chelating capacity that is crucial for urease inhibition. The analysis underscores the potential of CA5, CA8, and CA12 as novel HpU inhibitors. Finally, we compare our candidates with the chemical space of urease inhibitors finding physicochemical similarities with potent agents such as thiourea.

Phytochemicals as Antimicrobials: Prospecting Himalayan Medicinal Plants as Source of Alternate Medicine to Combat Antimicrobial Resistance

Among all available antimicrobials, antibiotics hold a prime position in the treatment of infectious diseases. However, the emergence of antimicrobial resistance (AMR) has posed a serious threat to the effectiveness of antibiotics, resulting in increased morbidity, mortality, and escalation in healthcare costs causing a global health crisis. The overuse and misuse of antibiotics in global healthcare setups have accelerated the development and spread of AMR, leading to the emergence of multidrug-resistant (MDR) pathogens, which further limits treatment options. This creates a critical need to explore alternative approaches to combat bacterial infections. Phytochemicals have gained attention as a potential source of alternative medicine to address the challenge of AMR. Phytochemicals are structurally and functionally diverse and have multitarget antimicrobial effects, disrupting essential cellular activities. Given the promising results of plant-based antimicrobials, coupled with the slow discovery of novel antibiotics, it has become highly imperative to explore the vast repository of phytocompounds to overcome the looming catastrophe of AMR. This review summarizes the emergence of AMR towards existing antibiotics and potent phytochemicals having antimicrobial activities, along with a comprehensive overview of 123 Himalayan medicinal plants reported to possess antimicrobial phytocompounds, thus compiling the existing information that will help researchers in the exploration of phytochemicals to combat AMR.

Inhibitory activity of catecholic phosphonic and phosphinic acids against Helicobacter pylori ureolysis

Catechols have been reported to be potent covalent inhibitors of ureases, and they exhibit activity by modifying cysteine residues at the entrance to enzymatic active sites. Following these principles, we designed and synthesized novel catecholic derivatives that contained carboxylate and phosphonic/phosphinic functionalities and assumed expanded specific interactions. When studying the chemical stability of the molecules, we found that their intrinsic acidity catalyzes spontaneous esterification/hydrolysis reactions in methanol or water solutions, respectively. Regarding biological activity, the most promising compound, 2-(3,4-dihydroxyphenyl)-3-phosphonopropionic acid (15), exhibited significant anti-urease potential (K_i = 2.36 μM, Sporosarcinia pasteurii urease), which was reflected in the antiureolytic effect in live Helicobacter pylori cells at a submicromolar concentration (IC₅₀ = 0.75 μM). As illustrated by molecular modeling, this compound was bound in the active site of urease through a set of concerted electrostatic and hydrogen bond interactions. The antiureolytic activity of catecholic phosphonic acids could be specific because these compounds were chemically inert and not cytotoxic to eukaryotic cells.

A high-throughput visual screening method for p-hydroxybenzoate hydroxylase to increase phenolic compounds biosynthesis

Background

Gallic acid (GA) and pyrogallol are phenolic hydroxyl compounds and have diverse biological activities. Microbial-based biosynthesis, as an ecofriendly method, has been used for GA and pyrogallol production. In GA and pyrogallol biosynthetic pathways, the low hydroxylation activity of p-hydroxybenzoate hydroxylase (PobA) towards 3,4-dihydroxybenzoic acid (3,4-DHBA) limited the high-level biosynthesis of GA and pyrogallol.

Results

This work reported a high activity PobA mutant (Y385F/T294A/V349A PobA) towards 3,4-DHBA. This mutant was screened out from a PobA random mutagenesis library through a novel naked eye visual screening method. In vitro enzyme assay showed this mutant has a k_cat/K_m of 0.059 μM⁻¹ s⁻¹ towards 3,4-DHBA, which was 4.92-fold higher than the reported mutant (Y385F/T294A PobA). Molecular docking simulation provided the possible catalytic mechanism explanation of the high activity mutant. Expression of this mutant in E. coli BW25113 (Fʹ) can generate 840 ± 23 mg/L GA from 1000 mg/L 3,4-DHBA. After that, this mutant was assembled into a de novo GA biosynthetic pathway. Subsequently, this pathway was introduced into a 3,4-DHBA-producing strain (E. coli BW25113 (Fʹ)ΔaroE) to achieve 301 ± 15 mg/L GA production from simple carbon sources. Similarly, assembling this mutant into a de novo pyrogallol biosynthetic pathway enabled 129 ± 15 mg/L pyrogallol production.

Conclusions

This work established an efficient screening method and generated a high activity PobA mutant. Assembling this mutant into de novo GA and pyrogallol biosynthetic pathways achieved the production of these two compounds from glucose. Besides, this mutant has great potential for the production of GA or pyrogallol derivatives. The screening method could be used for other GA biosynthesis-related enzymes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13068-022-02142-w.

Metabolic Profiling by GC-MS, In Vitro Biological Potential, and In Silico Molecular Docking Studies of Verbena officinalis

Verbena officinalis L. is a traditionally important medicinal herb that has a rich source of bioactive phytoconstituents with biological benefits. The objective of this study was to assess the metabolic profile and in vitro biological potential of V. officinalis. The bioactive phytoconstituents were evaluated by preliminary phytochemical studies, estimation of polyphenolic contents, and gas chromatography-mass spectrometry (GC-MS) analysis of all fractions (crude methanolic, n-hexane, ethyl acetate, and n-butanol) of V. officinalis. The biological investigation was performed by different assays including antioxidant assays (DPPH, ABTS, CUPRAC, and FRAP), enzyme inhibition assays (urease and α-glucosidase), and hemolytic activity. The ethyl acetate extract had the maximum concentration of total phenolic and total flavonoid contents (394.30 ± 1.09 mg GAE·g^-1 DE and 137.35 ± 0.94 mg QE·g^-1 DE, respectively). Significant antioxidant potential was observed in all fractions by all four antioxidant methods. Maximum urease inhibitory activity in terms of IC₅₀ value was shown by ethyl acetate fraction (10 ± 1.60 µg mL^-1) in comparison to standard hydroxy urea (9.8 ± 1.20 µg·mL^-1). The n-hexane extract showed good α-glucosidase inhibitory efficacy (420 ± 20 µg·mL^-1) as compared to other extract/fractions. Minimum hemolytic activity was found in crude methanolic fraction (6.5 ± 0.94%) in comparison to positive standard Triton X-100 (93.5 ± 0.48%). The GC-MS analysis of all extract/fractions of V. officinalis including crude methanolic, n-hexane, ethyl acetate, and n-butanol fractions, resulted in the identification of 24, 56, 25, and 9 bioactive compounds, respectively, with 80% quality index. Furthermore, the bioactive compounds identified by GC-MS were analyzed using in silico molecular docking studies to determine the binding affinity between ligands and enzymes (urease and α-glucosidase). In conclusion, V. officinalis possesses multiple therapeutical potentials, and further research is needed to explore its use in the treatment of chronic diseases.

A review on the structures and biological activities of anti-Helicobacter pylori agents

Helicobacter pylori is one of the main causal risk factor in the generation of chronic gastritis, gastroduodenal ulcers and gastric carcinoma. Thus, the eradication of H. pylori infection is an important way for preventing and managing the gastric diseases. Multiple-therapy with several antibacterial agents is used for the eradication of H. pylori infections; however the increase of resistance to H. pylori strains has resulted in unsatisfactory eradication and unsuccessful treatment. Furthermore, the combination therapy with high dosing leads to the disruption of intestinal microbial flora and undesired side effects. Therefore, the search for new therapeutic agents with high selectivity against H. pylori is a field of current interest. In recent years, diverse compounds originating from natural sources or synthetic drug design programs were evaluated and tried to optimize for applying against H. pylori. In this review, we have described various classes of anti-H. pylori compounds, their structure-activity relationship studies, and mechanism of actions, which could be useful for the development of new drugs for the treatment of H. pylori infections.

Targeting Salmonella Typhimurium Invasion and Intracellular Survival Using Pyrogallol

Salmonella enterica serovar Typhimurium, an intracellular pathogen, evades the host immune response mechanisms to cause gastroenteritis in animals and humans. After invading the host cells, the bacteria proliferate in Salmonella-containing vacuole (SCV) and escapes from antimicrobial therapy. Moreover, Salmonella Typhimurium develops resistance to various antimicrobials including, fluoroquinolones. Treating intracellular bacteria and combating drug resistance is essential to limit the infection rate. One way of overcoming these challenges is through combination therapy. In this study, Pyrogallol (PG), a polyphenol, is combined with marbofloxacin (MAR) to investigate its effect on Salmonella Typhimurium invasion and intracellular survival inhibition. The Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PG against Salmonella Typhimurium were 128 and 256 μg/mL, respectively. The lowest fractional inhibitory concentration (FIC) index for a combination of PG and MAR was 0.5. The gentamycin protection assay revealed that PG (30 μg/mL) alone and in combination with sub-MIC of MAR inhibited 72.75 and 76.18% of the invading bacteria in Caco-2 cells, respectively. Besides, the intracellular survival of Salmonella Typhimurium was reduced by 7.69 and 74.36% in treatment with PG alone and combined with sub-MIC of MAR, respectively, which was visualized by the confocal microscopy. PG has also shown to increase the intracellular accumulation of fluoroquinolone by 15.2 and 34.9% at 30 and 100 μg/mL concentration, respectively. Quantitative real-time PCR demonstrated PG suppressed the genetic expression of hilA, invF, sipB, and acrA by 14.6, 15.4, 13.6, and 36%, respectively. However, the downregulation of hilA, invF, sipB, and acrA increased to 80, 74.6, 78, and 70.1%, in combination with sub-MIC of MAR, respectively. Similarly, PG combined with MAR inhibited the expression of sdiA, srgE, and rck genes by 78.6, 62.8, and 61.8%, respectively. In conclusion, PG has shown antimicrobial activity against Salmonella Typhimurium alone and in combination with MAR. It also inhibited invasion and intracellular survival of the bacteria through downregulation of quorum sensing, invading virulence, and efflux pump genes. Hence, PG could be a potential antimicrobial candidate which could limit the intracellular survival and replication of Salmonella Typhimurium.

Flavonoid analogues as urease inhibitors: Synthesis, biological evaluation, molecular docking studies and in-silico ADME evaluation

A series of novel flavonoid analogues were designed and synthesized. The aimed compounds for urease inhibitory activities were clearly superior to the control drug thiourea (more than 10 times). Among these compounds, L2 (IC₅₀ = 1.343 µM) and L12 (IC₅₀ = 1.207 µM) exhibited the most excellent urease inhibitory activity in vitro. The molecular dockings of L2, L12 and L22 into urease were performed to explore the binding modes and their structure-activity relationship. Furthermore, these aimed compounds showed good druggable properties.

Lead Molecules for Targeted Urease Inhibition: An Updated Review from 2010 -2018

The field of enzyme inhibition is a tremendous and quickly growing territory of research. Urease a nickel containing metalloenzyme found in bacteria, algae, fungi, and plants brings hydrolysis of urea and plays important role in environmental nitrogen cycle. Apart from this it was found to be responsible for many pathological conditions due to its presence in many microorganisms such as H. Pylori, a ureolytic bacteria having urease which elevates pH of gastric medium by hydrolyzing urea present in alimentary canal and help the bacteria to colonize and spread infection. Due to the infections caused by the various bacterial ureases such as Bacillus pasteurii, Brucella abortus, H. pylori, H. mustelae, Klebsiella aerogenes, Klebsiella tuberculosis, Mycobacterium tuberculosis, Pseudomonas putida, Sporosarcina pasteurii and Yersinia enterocolitica, it has been the current topic of today's research. About a wide range of compounds from the exhaustive literature survey has been discussed in this review which is enveloped into two expansive classes, as Inhibitors from synthetic origin and Inhibitors from natural origin. Moreover active site details of enzyme, mechanism of catalysis of substrate by enzyme, uses of plant urease and its pathogenic behavior has been included in the current review. So, overall, this review article diagrams the current landscape of the developments in the improvements in the thriving field of urease inhibitory movement in medicinal chemistry from year 2010 to 2018, with an emphasis on mechanism of action of inhibitors that may be used for more development of recent and strong urease inhibitors and open up new doors for assist examinations in a standout amongst the most lively and promising regions of research.

N-monoarylacetothioureas as potent urease inhibitors: synthesis, SAR, and biological evaluation

A urease inhibitor with good in vivo profile is considered as an alternative agent for treating infections caused by urease-producing bacteria such as Helicobacter pylori. Here, we report a series of N-monosubstituted thioureas, which act as effective urease inhibitors with very low cytotoxicity. One compound (b19) was evaluated in detail and shows promising features for further development as an agent to treat H. pylori caused diseases. Excellent values for the inhibition of b19 against both extracted urease and urease in intact cell were observed, which shows IC₅₀ values of 0.16 ± 0.05 and 3.86 ± 0.10 µM, being 170- and 44-fold more potent than the clinically used drug AHA, respectively. Docking simulations suggested that the monosubstituted thiourea moiety penetrates urea binding site. In addition, b19 is a rapid and reversible urease inhibitor, and displays nM affinity to urease with very slow dissociation (k_off=1.60 × 10⁻³ s⁻¹) from the catalytic domain.

Studies on Isoniazid Derivatives through a Medicinal Chemistry Approach for the Identification of New Inhibitors of Urease and Inflammatory Markers

A library of thiosemicarbazide derivatives of isoniazid 3-27, was synthesized and evaluated for their anti-inflammatory and urease inhibition activities, by using in vitro bioassays. Among these compounds 9, 10, 12, 21, and 26 were identified as new derivatives. Prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs) and infections caused by Helicobacter pylori (ureolytic bacteria), are the two most significant causes of gastric and peptic ulcers. We focused on the identification of the dual inhibitors of inflammation and urease enzyme. Compound 23 was identified as the best dual inhibitor of inflammation (ROS; IC50 = 12.3 µg/mL), and urease enzyme inhibition activity (IC50 = 22.4 µM). Many of these compounds showed comparable activities to the standard anti-inflammatory drug (ibuprofen, IC50 = 11.2 µg/mL) and urease inhibitor (thiourea/acetohydraoxamic acid, IC50 = 21.1/20.3 µM). Compound 12 was found to be the most potent urease inhibitor (IC50 = 12.3 µM) and good inhibitor of inflammation (IC50 = 27.7 µg/mL). Compounds 19, 11, 13, 9, 17, 10, and 16, were also found to be potent inhibitors of urease. Cytotoxicity was also evaluated and all the compounds were found to be non-cytotoxic, except compound 18 and the parent drug isoniazid (IC50 = 29.5 and 28.5 µM, respectively).

Synthesis of β-Ketosulfone Derivatives As New Non-Cytotoxic Urease Inhibitors In Vitro

BACKGROUND

Peptic ulcer and urolithiasis are largely due to infection caused by ureaseproducing bacteria. Therefore, the discovery of urease inhibitors is an important area of medicinal chemistry research.

OBJECTIVE

The main aim of the work was to identify novel urease inhibitors with no cytotoxicity.

METHODS

During the current study, a series of β-ketosulfones 1-26 was synthesized in two steps and evaluated for their in vitro urease inhibition potential.

RESULTS

Out of twenty-six compounds, seventeen have shown good to significant urease inhibitory activity with IC50 values ranging between 49.93-351.46 µM, in comparison to standard thiourea (IC50 = 21 ± 0.11 µM). Moreover, all compounds found to be non-cytotoxic against normal 3T3 cell line.

CONCLUSION

This study has identified β-ketosulfones as novel and non-cytotoxic urease inhibitors.

F. A review on the development of urease inhibitors as antimicrobial agents against pathogenic bacteria

Ureases are enzymes that hydrolyze urea into ammonium and carbon dioxide. They have received considerable attention due to their impacts on living organism health, since the urease activity in microorganisms, particularly in bacteria, are potential causes and/or factors contributing to the persistence of some pathogen infections. This review compiles examples of the most potent antiurease organic substances. Emphasis was given to systematic screening studies on the inhibitory activity of rationally designed series of compounds with the corresponding SAR considerations. Ureases of Canavalia ensiformis, the usual model in antiureolytic studies, are emphasized. Although the active site of this class of hydrolases is conserved among bacteria and vegetal ureases, the same is not observerd for allosteric site. Therefore, inhibitors acting by participating in interactions with the allosteric site are more susceptible to a potential lack of association among their inhibitory profile for different ureases. The information about the inhibitory activity of different classes of compounds can be usefull to guide the development of new urease inhibitors that may be used in future in small molecular therapy against pathogenic bacteria.

Developing potential Helicobacter pylori urease inhibitors from novel oxoindoline derivatives: Synthesis, biological evaluation and in silico study

By recruiting the important moiety from Shikonin, a series of novel oxoindoline derivatives S1-S20 have been synthesized for inhibiting H. pylori urease. The most potent compound S18 displayed better activity (IC₅₀ = 0.71 μM; MIC = 0.48 μM) than the positive controls AHA (IC₅₀ = 17.2 μM) and Metronidazole (MIC = 31.3 μM). With low cytotoxicity, it showed considerable potential for further development. Docking simulation revealed the possible binding pattern of this series. 3D QSAR model was built to discuss SAR and give useful hints for future modification.

Phytochemistry and pharmacological potential of Cassia absus - a review

OBJECTIVES

Cassia absus is a plant of the family fabaceae with Ayurvedic ethnomedical records. It is used in traditional medicine for the treatment of bronchitis, asthma, cough, conjunctivitis, leucoderma, renal and hepatic diseases, constipation, tumors, venereal ulcer, headache, hemorrhoids and wound healing. Preliminary in vitro and in vivo studies have provided valuable scientific evidence for its use. This review aims to summarize reported pharmacognosy, traditional uses, phytochemistry and pharmacological potential of C. absus while identifying potential areas of further research of plant.

KEY FINDINGS

The review comprises literature pertaining to the evidence base therapeutic potential, pharmacognosy and phytochemistry of C. absus spanning from 1935 to 2016 using published articles in peer-reviewed journals, ethno botanical text books, and worldwide accepted scientific databases via electronic search (Elsevier, Google Scholar, PubMed, Scopus, Springer, Web of Science, Wiley online library). Kew Botanical Garden databases and the Plant List were used to authenticate the scientific names. Different pharmacological experiments in many in-vitro and in-vivo models have proved the potential of C. absus with antihypertensive, antifertility, antifungal, anti-inflammatory, anti-hyperglycemic, anti-glycation, antibacterial activity, α- amylase inhibitory activity, antioxidant and reducing activitity etc. chaksine, iso-chaksine, saturated and unsaturated fatty acids, chrysophanol, aloe-emodin and a wide range of chemical compounds have also been reported. Toxicity studies reveal the nontoxic nature of C. absus at a dose of 2000 mg/kg, however, plant possess reproductive toxicity and can be used as birth control or abortifacient.

SUMMARY

Reported activities suggest that there is sufficient pharmacological potential for developing C. absus as a drug for hypertension, infections, diabetes and its complications. However, heterogeneity in study protocol and conflicting results mask the ability to replicate these studies. So, future studies should be replicated in line with best practices. More toxicological studies would aid the progress to clinical trial studies. Various ethno medical uses of C. absus have not been evaluated yet.

Anti-Influenza Virus (H5N1) Activity Screening on the Phloroglucinols from Rhizomes of Dryopteris crassirhizoma

For screening the active phloroglucinols on influenza virus (H5N1) from Dryopteris crassirhizoma NaKai, a database was established including twenty-three phloroglucinols that had been isolated from Dryopteris crassirhizoma. Their inhibitory effect on the neuraminidase (NA) of influenza virus H5N1 was screened by molecular docking. As a result, three candidates were selected. The rhizomes of D. crassirhizoma were subjected to isolation and purification processes to obtain the inhibitor candidates. Thirteen phloroglucinols were obtained, including three selected candidates and two new phloroglucinols. The five phloroglucinols were investigated for their inhibitory activity on NA in vitro. The results showed that dryocrassin ABBA and filixic acid ABA exhibited inhibitory effects on NA with IC50 as 18.59 ± 4.53 and 29.57 ± 2.48 μM, respectively, and the other three phloroglucinols showed moderate inhibitory activity. Moreover, the anti-influenza virus (H5N1) activity and cytotoxicity of dryocrassin ABBA and filixic acid ABA were tested on Madin-Darby canine kidney (MDCK) cells with the cell counting kit-8 (CCK8) method. The results confirmed that dryocrassin ABBA exhibited an inhibitory activity with low cytotoxicity (TC50 > 400 μM) against influenza virus (H5N1) which will have to be investigated in further detail. In conclusion, phloroglucinols from D. crassirhizoma were shown to have anti-influenza virus activity, and especially dryocrassin ABBA, one of the phloroglucinols, may have the potential to control influenza virus (H5N1) infection.

Iminothiazoline-Sulfonamide Hybrids as Jack Bean Urease Inhibitors; Synthesis, Kinetic Mechanism and Computational Molecular Modeling

The present work reports the synthesis of several 2-iminothiazoline derivatives of sulfanilamide (3a-j) as inhibitors of jack bean ureases. The title compounds were synthesized by the heterocyclization of sulfanilamide thioureas with propragyl bromide in dry ethanol in the presence of 1,8-Diazabicyclo[5.4.0]undec-7-ene as a base. All of the compounds showed higher urease inhibitory activity than the standard thiourea. The compounds (3h) and (3i) exhibited excellent enzyme inhibitory activity with IC50 0.064 and 0.058 μm, respectively, while IC50 of thiourea is 20.9 μm. The kinetic mechanism analyzed by Dixon plot showed that compound (3h) is a mixed-type inhibitor while (3i) is a competitive one. Docking studies suggested that Asp633, Ala636, His492, Ala440, Lue523, Asp494 and Arg439 are the major interacting residues in the binding site of the protein and may have an instrumental role in the inhibition of enzyme's function. 2-iminothiazoline analogues (3a-j) showed good docking score (-10.6466 to -8.7215 Kcal/mol) and binding energy (London dG ranging from -14.4825 to -10.4087 Kcal/mol) which is far better than the standard thiourea (binding score in S field -4.5790 Kcal/mol London dG -4.7726 Kcal/mol). Our results inferred compound (3i) may serve as a structural model for the design of most potent urease inhibitors.

Bis(aminomethyl)phosphinic Acid, a Highly Promising Scaffold for the Development of Bacterial Urease Inhibitors

Inhibitors of bacterial ureases are considered to be promising compounds in the treatment of infections caused by Helicobacter pylori in the gastric tract and/or by urealytic bacteria (e.g., Proteus species) in the urinary tract. A new, extended transition state scaffold, bis(aminomethyl)phosphinic acid, was successfully explored for the construction of effective enzyme inhibitors. A reliable methodology for the synthesis of phosphinate analogues in a three-component Mannich-type reaction was elaborated. The obtained molecules were assayed against ureases purified from Sporosarcina pasteurii and Proteus mirabilis, and aminomethyl(N-n-hexylaminomethyl)phosphinic acid was found to be the most potent inhibitor, with a K i = 108 nM against the S. pasteurii enzyme.

Urease Inhibitory Activity of Aerial Parts of Artemisia scoparia: Exploration in an In Vitro Study

Artimisia scoparia has been used in the treatment of different disorders including ulcers. The current study was therefore designed to investigate the aerial parts of  Artemisia scoparia (crude extract, total sterol and flavonoidal contents, and aqueous fraction) for its urease inhibitory potential. The crude of the plant evoked marked attenuation on urease activity, when tested in various concentrations with IC50 values of 4.06 mg/ml. The inhibitory potential was further augmented in the aqueous fraction (IC50: 2.30 mg/ml) of the plant. When the total sterol and flavonoidal contents were challenged against urease, both showed concentration dependent activity; the latter showed maximum potency with IC50 values of 8.04 and 2.10 mg/ml, respectively. In short, the aerial parts of the plant demonstrated marked antagonism on urease and thus our study validated the traditional use of Artemisia scoparia in the treatment of ulcer.

Antibacterial, antiurease, and antioxidant activities of some arylidene barbiturates

Some series of arylidene barbiturates and thiobarbiturates were evaluated for their antibacterial, antioxidant, and urease inhibition activities. The arylidene barbiturates and thiobarbiturates were tested for antimicrobial activity using the agar well diffusion technique against 13 bacteria. The synthesized compounds (1a-g) were screened for antiurease and antioxidant activities. The results showed that the synthesized compounds (1a-g) had effective antiurease, antioxidant, and antibacterial activities.

Some monohydroxy tetradecanoic acid isomers as novel urease and elastase inhibitors and as new antioxidants

A series of some 3-,6-,7-,9-,12- monohydroxy tetradecanoic acids were evaluated for their antiurease, antielastase and antioxidant activities for the first time in this study. All the test compounds exhibited antioxidant, antielastase and antiurease activities. The relationship between the position of the hydroxy group and the enzyme inhibition effect is studied in this work. The mentioned biological activities are depending on the position of hydroxy group of tetradecanoic acid isomers. The results obtained in this work are indicating that 3-,6-,7-,9-,12-monohydroxy tetradecanoic acid isomers can be used in agriculture, pharmacy and cosmetic industries due to their excellent antielastase, antiurease and antioxidant activities.