scholarly journals Role for dithiolopyrrolones in disrupting bacterial metal homeostasis

2017 ◽  
Vol 114 (10) ◽  
pp. 2717-2722 ◽  
Author(s):  
Andrew N. Chan ◽  
Anthony L. Shiver ◽  
Walter J. Wever ◽  
Sayyeda Zeenat A. Razvi ◽  
Matthew F. Traxler ◽  
...  
Keyword(s):  
Natural Products ◽  
Rna Polymerase ◽  
Metal Binding ◽  
Antimicrobial Activities ◽  
Metal Homeostasis ◽  
Chemical Genomics ◽  
Chemical Structures ◽  
High Affinity ◽  
Metal Chelating

Natural products harbor unique and complex structures that provide valuable antibiotic scaffolds. With an increase in antibiotic resistance, natural products once again hold promise for new antimicrobial therapies, especially those with unique scaffolds that have been overlooked due to a lack of understanding of how they function. Dithiolopyrrolones (DTPs) are an underexplored class of disulfide-containing natural products, which exhibit potent antimicrobial activities against multidrug-resistant pathogens. DTPs were thought to target RNA polymerase, but conflicting observations leave the mechanisms elusive. Using a chemical genomics screen inEscherichia coli, we uncover a mode of action for DTPs—the disruption of metal homeostasis. We show that holomycin, a prototypical DTP, is reductively activated, and reduced holomycin chelates zinc with high affinity. Examination of reduced holomycin against zinc-dependent metalloenzymes revealed that it inhibitsE. coliclass II fructose bisphosphate aldolase, but not RNA polymerase. Reduced holomycin also strongly inhibits metallo–β-lactamases in vitro, major contributors to clinical carbapenem resistance, by removing active site zinc. These results indicate that holomycin is an intracellular metal-chelating antibiotic that inhibits a subset of metalloenzymes and that RNA polymerase is unlikely to be the primary target. Our work establishes a link between the chemical structures of DTPs and their antimicrobial action; the ene-dithiol group of DTPs enables high-affinity metal binding as a central mechanism to inhibit metabolic processes. Our study also validates the use of chemical genomics in characterizing modes of actions of antibiotics and emphasizes the potential of metal-chelating natural products in antimicrobial therapy.

Novel Phytochemical Constituents and their Potential to Manage Diabetes

2020 ◽  
Vol 26 ◽  
Author(s):  
Shaik Ibrahim Khalivulla ◽  
Arifullah Mohammed ◽  
Kokkanti Mallikarjuna
Keyword(s):  
Natural Products ◽  
Large Population ◽  
World Health ◽  
In Vivo Studies ◽  
Antidiabetic Activity ◽  
Therapeutic Drug ◽  
Pharmacological Activities ◽  
Chemical Structures

Background: Diabetes is a chronic disease affecting a large population worldwide and stands as one of the major global health challenges to be tackled. According to World Health Organization, about 400 million are having diabetes worldwide and it is the seventh leading cause of deaths in 2016. Plant based natural products had been in use from ancient time as ethnomedicine for the treatment of several diseases including diabetes. As a result of that, there are several reports on plant based natural products displaying antidiabetic activity. In the current review, such antidiabetic potential compounds reported from all plant sources along with their chemical structures are collected, presented and discussed. This kind of reports are essential to pool the available information to one source followed by statistical analysis and screening to check the efficacy of all known compounds in a comparative sense. This kind of analysis can give rise to few numbers of potential compounds from hundreds, whom can further be screened through in vitro and in vivo studies, and human trails leading to the drug development. Methods: Phytochemicals along with their potential antidiabetic property were classified according to their basic chemical skeleton. The chemical structures of all the compounds with antidiabetic activities were elucidated in the present review. In addition to this, the distribution and their other remarkable pharmacological activities of each species is also included. Results: The scrutiny of literature led to identification of 44 plants with antidiabetic compounds (70) and other pharmacological activities. For the sake of information, the distribution of each species in the world is given. Many plant derivatives may exert antidiabetic properties by improving or mimicking the insulin production or action. Different classes of compounds including sulfur compounds (1-4), alkaloids (5-11), phenolic compounds (12-17), tannins (18-23), phenylpropanoids (24-27), xanthanoids (28-31), amino acid (32), stilbenoid (33), benzofuran (34), coumarin (35), flavonoids (36-49) and terpenoids (50-70) were found to be active potential compounds for antidiabetic activity. Of the 70 listed compounds, majorly 17 compounds are from triterpenoids, 13 flavonoids and 7 are from alkaloids. Among all the 44 plant species, maximum number (7) of compounds are reported from Lagerstroemia speciosa followed by Momordica charantia (6) and S. oblonga with 5 compounds. Conclusion: This is the first paper to summarize the established chemical structures of phytochemicals that have been successfully screened for antidiabetic potential and their mechanisms of inhibition. The reported compounds could be considered as potential lead molecules for the treatment of type-2 diabetes. Further, molecular and clinical trials are required to select and establish the therapeutic drug candidates.

Hemoglobin F (HbF) inducers; History, Structure and Efficacies

2021 ◽  
Vol 21 ◽  
Author(s):  
Zahra Hashemi ◽  
Mohammad Ali Ebrahimzadeh
Keyword(s):  
Clinical Trials ◽  
Natural Products ◽  
Biological Activities ◽  
Globin Gene ◽  
Beta Thalassemia ◽  
Gene Promoters ◽  
Hemoglobin F ◽  
Chemical Structures

Abstract: Inherited beta-thalassemia is a major disease caused by irregular production of hemoglobin through reducing beta-globin chains. It has been observed that increasing fetal hemoglobin (HbF) production improves symptoms in the patients. Therefore, an increase in the level of HbF has been an operative approach for treating patients with beta-thalassemia. This review represents compounds with biological activities and pharmacological properties that can promote the HBF level and therefore used in the β-thalassemia patients' therapy. Various natural products with different mechanisms of action can be helpful in this medication cure. Clinical trials were efficient in improving the signs of patients. Association of in vivo, and in vitro studies of HbF induction and γ-globin mRNA growth displays that in vitro experiments could be an indicator of the in vivo response. The current study shows that; (a) HbF inducers can be grouped in several classes based on their chemical structures and mechanism of actions; b) According to several clinical trials, well-known drugs such as hydroxyurea and decitabine are useful HbF inducers; (c) The cellular biosensor K562 carrying genes under the control of the human γ-globin and β-globin gene promoters were applied during the researches; d) New natural products and lead compounds were found based on various studies as HbF inducers.

scholarly journals Secondary Metabolites from Gorgonian Corals of the Genus Eunicella: Structural Characterizations, Biological Activities, and Synthetic Approaches

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 129
Author(s):  
Dario Matulja ◽  
Maria Kolympadi Markovic ◽  
Gabriela Ambrožić ◽  
Sylvain Laclef ◽  
Sandra Kraljević Pavelić ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Biological Activities ◽  
Structural Characteristics ◽  
Antimicrobial Activities ◽  
Chemical Structures ◽  
Gorgonian Corals ◽  
Synthetic Approaches ◽  
Further Development

Gorgonian corals, which belong to the genus Eunicella, are known as natural sources of diverse compounds with unique structural characteristics and interesting bioactivities both in vitro and in vivo. This review is focused primarily on the secondary metabolites isolated from various Eunicella species. The chemical structures of 64 compounds were divided into three main groups and comprehensively presented: a) terpenoids, b) sterols, and c) alkaloids and nucleosides. The observed biological activities of depicted metabolites with an impact on cytotoxic, anti-inflammatory, and antimicrobial activities were reviewed. The most promising biological activities of certain metabolites point to potential candidates for further development in pharmaceutical, cosmetic, and other industries, and are highlighted. Total synthesis or the synthetic approaches towards the desired skeletons or natural products are also summarized.

scholarly journals Regulation of Antimycin Biosynthesis Is Controlled by the ClpXP Protease

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Bohdan Bilyk ◽  
Sora Kim ◽  
Asif Fazal ◽  
Tania A. Baker ◽  
Ryan F. Seipke
Keyword(s):  
Natural Products ◽  
Rna Polymerase ◽  
Natural Product ◽  
Morphological Differentiation ◽  
Dynamic Responses ◽  
Biosynthetic Pathways ◽  
Recognition Sequence ◽  
Σ Factor

ABSTRACT The survival of any microbe relies on its ability to respond to environmental change. Use of extracytoplasmic function (ECF) RNA polymerase sigma (σ) factors is a major strategy enabling dynamic responses to extracellular signals. Streptomyces species harbor a large number of ECF σ factors, nearly all of which are uncharacterized, but those that have been characterized generally regulate genes required for morphological differentiation and/or response to environmental stress, except for σAntA, which regulates starter-unit biosynthesis in the production of antimycin, an anticancer compound. Unlike a canonical ECF σ factor, whose activity is regulated by a cognate anti-σ factor, σAntA is an orphan, raising intriguing questions about how its activity may be controlled. Here, we reconstituted in vitro ClpXP proteolysis of σAntA but not of a variant lacking a C-terminal di-alanine motif. Furthermore, we show that the abundance of σAntA in vivo was enhanced by removal of the ClpXP recognition sequence and that levels of the protein rose when cellular ClpXP protease activity was abolished. These data establish direct proteolysis as an alternative and, thus far, unique control strategy for an ECF RNA polymerase σ factor and expands the paradigmatic understanding of microbial signal transduction regulation. IMPORTANCE Natural products produced by Streptomyces species underpin many industrially and medically important compounds. However, the majority of the ∼30 biosynthetic pathways harbored by an average species are not expressed in the laboratory. This unrevealed biochemical diversity is believed to comprise an untapped resource for natural product drug discovery. Major roadblocks preventing the exploitation of unexpressed biosynthetic pathways are a lack of insight into their regulation and limited technology for activating their expression. Our findings reveal that the abundance of σAntA, which is the cluster-situated regulator of antimycin biosynthesis, is controlled by the ClpXP protease. These data link proteolysis to the regulation of natural product biosynthesis for the first time to our knowledge, and we anticipate that this will emerge as a major strategy by which actinobacteria regulate production of their natural products. Further study of this process will advance understanding of how expression of secondary metabolism is controlled and will aid pursuit of activating unexpressed biosynthetic pathways.

Two highly acetylated sterols from the marine sponge Dysidea sp.

2017 ◽  
Vol 72 (1) ◽  
pp. 49-52 ◽  
Author(s):  
Yu Lu ◽  
Ming Zhao
Keyword(s):  
High Resolution ◽  
Mass Spectroscopy ◽  
2D Nmr ◽  
Antimicrobial Activities ◽  
Marine Sponges ◽  
Bacterial Strains ◽  
Chemical Structures ◽  
Spectroscopic Analyses ◽  
Impact Mass

AbstractTwo new highly acetylated steroids, named dysiroid A (1) and dysiroid B (2), together with a known compound (3) were isolated from the marine sponges Dysidea sp. The chemical structures of 1 and 2 were elucidated by spectroscopic analyses including 1D and 2D NMR experiments and high-resolution electrospray impact mass spectroscopy. Their in vitro antimicrobial activities against a panel of bacterial strains were evaluated. Compounds 1 and 2 showed potent activity against some of the strains with minimum inhibitory concentrations ranging from 4 to 8 μg mL−1.

scholarly journals Antidiabetic, Antimicrobial, and Molecular Profiling of Selected Medicinal Plants

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Babita Aryal ◽  
Purushottam Niraula ◽  
Karan Khadayat ◽  
Bikash Adhikari ◽  
Dadhiram Khatri Chhetri ◽  
...  
Keyword(s):  
Natural Products ◽  
Medicinal Plants ◽  
Ethyl Acetate ◽  
High Resolution Mass Spectrometry ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Ethyl Acetate Fraction ◽  
Antimicrobial Activities ◽  
Water Fraction

Natural products have been the center of attraction ever since they were discovered. Among them, plant-based natural products were popular as analgesics, anti-inflammatory, antidiabetic, and cosmetics and possess widespread biotechnological applications. The use of plant products as cosmetics and therapeutics is deep-rooted in Nepalese society. Although there are few ethnobotanical studies conducted, extensive research of these valuable medicinal plants has not been a priority due to the limitation of technology and infrastructure. Here, we selected 4 traditionally used medicinal plants to examine their bioactive properties and their enzyme inhibition potential. α-Glucosidase and α-amylase inhibitory activities were investigated using an in vitro model followed up by antioxidant and antimicrobial activities. The present study shows that ethyl acetate fraction of Melastoma melabathrium (IC50 9.1 ± 0.3 µg/mL) and water fraction Acacia catechu (IC50 9.0 ± 0.6 µg/mL) exhibit strong α-glucosidase inhibition. Likewise, the highest α-amylase inhibition was shown by crude extracts of Ficus religiosa (IC50 29.2 ± 1.2 µg/mL) and ethyl acetate fractions of Shorea robusta (IC50 69.3 ± 1.1 µg/mL), and the highest radical scavenging activity was shown by F. religiosa with an IC50 67.4 ± 0.6 µg/mL. Furthermore, to identify the metabolites within the fractions, we employed high-resolution mass spectrometry (LC-HRMS) and annotated 17 known metabolites which justify our assumption on activity. Of 4 medicinal plants examined, ethyl acetate fraction of S. robusta, ethyl acetate fraction of M. melabathrium, and water or ethyl acetate fraction of A. catechu extracts illustrated the best activities. With our study, we set up a foundation that provides authentic evidence to the community for use of these traditional plants. The annotated metabolites in this study support earlier experimental evidence towards the inhibition of enzymes. Further study is necessary to explore the clinical efficacy of these secondary molecules, which might be alternatives for the treatment of diabetes and pathogens.

scholarly journals Silica gel Supported Boric tri-Sulfuric Anhydride (SiO2-BTSA): an Efficient Catalytic System for the Synthesis of Phloroglucide analogs as Antimicrobial Agents

2019 ◽  
Author(s):  
Rahele Bargebid ◽  
Ali Khalafi-Nezhad ◽  
Kamiar Zomorodianc ◽  
Mahkameh Moradi ◽  
Soghra Khabnadideh
Keyword(s):  
Silica Gel ◽  
Antimicrobial Agents ◽  
Catalytic Amount ◽  
Antibacterial Activities ◽  
Antimicrobial Activities ◽  
Biological Properties ◽  
Dilution Method ◽  
Sulfuric Anhydride ◽  
Chemical Structures

An efficient procedure for the synthesis of polyhydroxyl aromatic compounds (phloroglucide analogs) is described. In this procedure a reaction was done between different 4-substituted phenols and 2,6-bis(hydroxymethy) phenols. The reactions proceed in the presence of catalytic amount of silica gel supported boric tri-sulfuric anhydride (SiO2-BTSA) in excellent yields. 16 compounds were synthesized (I1-I16). Chemical structures of all compounds were confirmed by spectroscopic methods. We optimized the chemical reactions in the presence of different acidic catalysts, different solvents and also different temperatures. Catalytic amounts of SiO2-BTSA in dichloroethane (DCE) was the best conditions. Some of the synthesized compounds were screened for their antimicrobial activities. Antifungal and antibacterial activities of the synthesized compounds were evaluated by broth micro dilution method as recommended by CLSI. Some of the tested compounds show good in vitro biological properties.

Synthesis, Biological Evaluation and Molecular Modeling Studies of Novel C (7) Modified Analogues of Chrysin

2020 ◽  
Vol 17 (7) ◽  
pp. 873-883
Author(s):  
Pulabala Ramesh ◽  
Vankadari Srinivasa Rao ◽  
Puchakayala Muralidhar Reddy ◽  
Katragadda Suresh Babu ◽  
Mutheneni Srinivasa Rao
Keyword(s):  
Natural Products ◽  
Biological Activity ◽  
Molecular Docking ◽  
Biological Activities ◽  
Antimicrobial Activities ◽  
Docking Studies ◽  
Biological Evaluation ◽  
Molecular Docking Studies ◽  
Fungal Strains

Background:: Most of the currently available pharmaceutical drugs are either natural products or analogues of natural products. Flavonoids are plant based natural polyphenolic compounds which exhibit a wide range of biological activities. Chrysin, a natural flavone, exhibits several biological activities like antiallergic, anti-inflammatory and anticancer. Many efforts were made to enhance the biological activity of chrysin. In continuation of our work on synthetic modifications of chrysin, amino-alcohol containing heterocyclic moiety is linked to chrysin at C (7) position to enhance its biological activity. Methods:: A series of new C (7) modified analogues of chrysin (3a-k) have been designed and synthesized in two steps. Chrysin, on reacting with epichlorohydrin in the presence of K2CO3 in DMF gave epoxide (2) which was made to react with cyclic secondary amines in the presence of LiBr to form the designed products (3a-k). All the synthesized compounds (3a-k) were well characterized by 1H NMR, 13C NMR and mass spectral data. The synthesized analogues (3a-k) were screened for their in vitro biological activities against a panel of bacterial and fungal strains. Molecular docking studies were also performed on these compounds with E. coli FabH (1HNJ) and S. cerevisiae (5EQB) enzymes, to support the observed biological activities. Results:: A series of new 2-hydroxy 3-amino chrysin derivatives (3a-k) were synthesized in two steps, starting with chrysin and their structures were characterized by spectral analysis. In vitro biological activities of these analogues against a panel of bacterial and fungal strains indicated that some of the derivatives manifested significant activities compared to standard drugs. Molecular docking and binding energy values were also correlated with experimental antimicrobial screening results. Lipinski’s “rule of five” is also obeyed by these analogues (3a-k) and exhibit drug-likeness. Conclusion:: In the present study, a series of new C (7) modified chrysin analogues (3a-k) were synthesized and tested for their in vitro antimicrobial activities. These biological studies indicated that some of the derivatives exhibited moderate to good antimicrobial activities compared to standard drugs. Molecular docking studies performed on these compounds correlated with the experimental antimicrobial activities. The results obtained in the study will be useful in establishing new drug entities to control the pathogenic epidemics.

scholarly journals Isolation and Antibacterial Activity of Indole Alkaloids from Pseudomonas aeruginosa UWI-1

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3744
Author(s):  
Antonio Ramkissoon ◽  
Mohindra Seepersaud ◽  
Anderson Maxwell ◽  
Jayaraj Jayaraman ◽  
Adesh Ramsubhag
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibacterial Activity ◽  
High Resolution Mass Spectrometry ◽  
Indole Alkaloid ◽  
Antimicrobial Activities ◽  
Mass Spectrometry Data ◽  
Gram Positive ◽  
Chemical Structures ◽  
Wide Range

In this study, we report the first isolation of three antibiotic indole alkaloid compounds from a Pseudomonad bacterium, Pseudomonas aeruginosa UWI-1. The bacterium was batch fermented in a modified Luria Broth medium and compounds were solvent extracted and isolated by bioassay-guided fractionation. The three compounds were identified as (1) tris(1H-indol-3-yl) methylium, (2) bis(indol-3-yl) phenylmethane, and (3) indolo (2, 1b) quinazoline-6, 12 dione. A combination of 1D and 2D NMR, high-resolution mass spectrometry data and comparison from related data from the literature was used to determine the chemical structures of the compounds. Compounds 1–3 were evaluated in vitro for their antimicrobial activities against a wide range of microorganisms using the broth microdilution technique. Compounds 1 and 2 displayed antibacterial activity against only Gram-positive pathogens, although 1 had significantly lower minimum inhibitory concentration (MIC) values than 2. Compound 3 displayed potent broad-spectrum antimicrobial activity against a range of Gram positive and negative bacteria. Several genes identified from the genome of P. aeruginosa UWI-1 were postulated to contribute to the biosynthesis of these compounds and we attempted to outline a possible route for bacterial synthesis. This study demonstrated the extended metabolic capability of Pseudomonas aeruginosa in synthesizing new chemotypes of bioactive compounds.

scholarly journals Exploring the Potential of Natural Products From Mangrove Rhizosphere Bacteria as Biopesticides Against Plant Diseases

Plant Disease ◽  
2019 ◽  
Vol 103 (11) ◽  
pp. 2925-2932 ◽  
Author(s):  
Lingyun Hao ◽  
Yu Wang ◽  
Xinqi Chen ◽  
Xiaoli Zheng ◽  
Si Chen ◽  
...  
Keyword(s):  
Natural Products ◽  
Antimicrobial Activities ◽  
Plant Diseases ◽  
Rhizosphere Bacteria ◽  
Vitro Assay ◽  
Bacterial Fermentation ◽  
Crude Extracts ◽  
Acanthus Ilicifolius ◽  
Plant Disease Management

With increasing concerns of the environmental problems associated with current fungicide application, investigation of alternative, environmentally compatible biopesticides for plant disease management is needed. A total of 113 strains associated with Acanthus ilicifolius Linn in the Maipo Reserve, Hong Kong, were isolated and identified. In vitro assay with crude extracts of bacterial fermentation cultures identified ∼26% of the isolates producing antimicrobial compounds against a variety of agriculturally important phytopathogens. Selected crude extracts with inhibition to Colletotrichum fructicola and Magnaporthe oryzae growth significantly suppressed anthracnose and rice blast development in pear fruits and rice plants, respectively, when applied at 50 μg ml−1. Furthermore, 10 of 14 selected crude extracts with good antimicrobial activities had no significant differences in toxicity to the genus Chlorella compared with the control when used at 25 μg ml−1, whereas Amistar Top and Mancozeb completely killed the alga under the same concentration. These data illustrate the potential of natural products from mangrove rhizosphere bacteria in future agricultural application.

Sign in / Sign up

Export Citation Format

Share Document