scholarly journals Broad Spectrum Anti-Quorum Sensing Activity of Tannin-Rich Crude Extracts of Indian Medicinal Plants

Scientifica ◽  
2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Varsha Shukla ◽  
Zarine Bhathena
Keyword(s):  
Quorum Sensing ◽  
Medicinal Plants ◽  
Broad Spectrum ◽  
Gram Negative Bacteria ◽  
High Concentration ◽  
Gram Positive ◽  
Gram Negative ◽  
Medicinal Plant Extracts ◽  
Wide Range ◽  
Autoinducing Peptides

Quorum sensing (QS) mechanisms have been demonstrated to have significance in expression of pathogenicity in infectious bacteria. In Gram negative bacteria the autoinducer molecules that mediate QS are acyl homoserine lactones (AHL) and in Gram positive bacteria they are peptides called autoinducing peptides (AIP). A screening of tannin-rich medicinal plants was attempted to identify extracts that could interrupt the QS mechanisms in both Gram positive and Gram negative bacteria over a wide range of concentrations and therefore potentially be potent agents that could act as broad spectrum QS inhibitors. Six out of the twelve Indian medicinal plant extracts that were analyzed exhibited anti-QS activity inChromobacterium violaceum12472 and inS.aureusstrain withagr:blaZfusion over a broad range of subinhibitory concentrations, indicating that the extracts contain high concentration of molecules that can interfere with the QS mechanisms mediated by AHL as well as AIP.

scholarly journals Autoinducer 2 Signaling via the Phosphotransferase FruA Drives Galactose Utilization by Streptococcus pneumoniae , Resulting in Hypervirulence

mBio ◽  
2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Claudia Trappetti ◽  
Lauren J. McAllister ◽  
Austen Chen ◽  
Hui Wang ◽  
Adrienne W. Paton ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Quorum Sensing ◽  
Capsular Polysaccharide ◽  
The Body ◽  
Gram Negative Bacteria ◽  
Phosphotransferase System ◽  
Gram Positive ◽  
Gram Negative ◽  
Autoinducer 2 ◽  
Leloir Pathway

ABSTRACT Communication between bacterial cells is crucial for the coordination of diverse cellular processes that facilitate environmental adaptation and, in the case of pathogenic species, virulence. This is achieved by the secretion and detection of small signaling molecules called autoinducers, a process termed quorum sensing. To date, the only signaling molecule recognized by both Gram-positive and Gram-negative bacteria is autoinducer 2 (AI-2), synthesized by the metabolic enzyme LuxS ( S -ribosylhomocysteine lyase) as a by-product of the activated methyl cycle. Homologues of LuxS are ubiquitous in bacteria, suggesting a key role in interspecies, as well as intraspecies, communication. Gram-negative bacteria sense and respond to AI-2 via the Lsr ABC transporter system or by the LuxP/LuxQ phosphorelay system. However, homologues of these systems are absent from Gram-positive bacteria and the AI-2 receptor is unknown. Here we show that in the major human pathogen Streptococcus pneumoniae , sensing of exogenous AI-2 is dependent on FruA, a fructose-specific phosphoenolpyruvate-phosphotransferase system that is highly conserved in Gram-positive pathogens. Importantly, AI-2 signaling via FruA enables the bacterium to utilize galactose as a carbon source and upregulates the Leloir pathway, thereby leading to increased production of capsular polysaccharide and a hypervirulent phenotype. IMPORTANCE S. pneumoniae is a Gram-positive bacterium frequently carried asymptomatically in the human nasopharynx. However, in a proportion of cases, it can spread to other sites of the body, causing life-threatening diseases that translate into massive global morbidity and mortality. Our data show that AI-2 signaling via FruA promotes the transition of the pneumococcus from colonization to invasion by facilitating the utilization of galactose, the principal sugar available in the upper respiratory tract. AI-2-mediated upregulation of Leloir pathway enzymes results in increased production of capsular polysaccharide and hypervirulence in a murine intranasal challenge model. This identifies the highly conserved FruA phosphotransferase system as a target for new antimicrobials based on the disruption of this generic quorum-sensing system.

Novel volatiles of skin-borne bacteria inhibit the growth of Gram-positive bacteria and affect quorum-sensing controlled phenotypes of Gram-negative bacteria

2016 ◽  
Vol 39 (8) ◽  
pp. 503-515 ◽  
Author(s):  
Marie Chantal Lemfack ◽  
Srinivasa Rao Ravella ◽  
Nicola Lorenz ◽  
Marco Kai ◽  
Kirsten Jung ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

scholarly journals Potential Assessment of Rumex spp. as a Source of Bioactive Compounds and Biological Activity

2021 ◽  
Vol 12 (2) ◽  
pp. 1824-1834
Keyword(s):  
Antioxidant Activity ◽  
Broad Spectrum ◽  
Pathogenic Bacteria ◽  
Gram Negative Bacteria ◽  
Meoh Extract ◽  
Gram Positive ◽  
Filter Paper Disc ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Antibacterial Performance

Secondary metabolites from the shoots and roots of three Rumex species collected from three different habitats were investigated (Rumex dentatus collected from cultivated land, R. pictus collected from the coastal desert and R. vesicarius collected from the inland desert) and tested for antioxidant activity as well as for anti-microbial activity against some human pathogenic bacteria. The present study indicated that the quantitative analysis of shoot and root extracts of three Rumex spp. were found to be rich in tannins and phenolics composition. The aerial parts of the three plants exhibited the highest significant values compared to the root parts. The MeOH extracts of Rumex species showed adequate antioxidant activity, wherein the IC50 values of the MeOH from the cultivated sample was 41.61 and 31.31 mg mL-1, coastal samples were 34.99 and 23.99 mg mL-1, while the sample of inland showed IC50 value of 41.59 and 31.67 mg mL-1, for root and shoot, respectively. Furthermore, using a filter paper disc assay, the MeOH extracts of the three Rumex species showed a substantial anti-microbial inhibitory effect on the growth of 10 pathogenic bacteria. According to sensitivity, the tested organisms could be sequenced as following: E. coli < K. pneumoniae ˂ S. typhi < P. aeruginosa for Gram-negative bacteria and B. subtilis < S. pneumoniae ˂ L. monocytoyenes < S. epidermis < S. aureus < B. cereus for Gram-positive bacteria. In addition, the antibacterial performance of R. dentatus root and R. vesicarius shoot MeOH extract is 100% broad spectrum against Gram-negative bacteria. A shoot of R. dentatus and R. pictus MeOH extract against Gram-positive bacteria is 83.3% broad spectrum. A further study is recommended for more characterization of the major compounds and assesses their efficiency and biosafety.

scholarly journals Antibacterial activity in the leaves of seven bitter medicinal plants of Bangladesh

1970 ◽  
Vol 18 ◽  
pp. 128-133 ◽  
Author(s):  
MTH Molla ◽  
MS Ahsan ◽  
MT Alam ◽  
ME Haque
Keyword(s):  
Antibacterial Activity ◽  
Bacillus Subtilis ◽  
Medicinal Plants ◽  
Plant Extracts ◽  
Salmonella Typhi ◽  
Antimicrobial Activities ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Ethanolic Extracts

Context: Development of resistance in human pathogens against conventional antibiotic necessitates searching indigenous medicinal plants having antibacterial property. Seven medicinal plants used actively in folklore, ayurvedic and traditional system of medicine were selected for the evaluation of their antimicrobial activity for this study.   Objectives: Evaluation of the effectiveness of some medicinal plant extracts against four Gram-positive and five Gram-negative bacteria.  Materials and Methods: The antibacterial activity of the crude ethanolic extracts obtained from the leaves of seven medicinal plants; viz., Andrographis paniculata, Catharanthus roseus, Adhatoda vasica, Vitex vegundo, Aloe vera, Flacortia ramontchi and Nyctanthes arbortristis were tested against nine bacteria at concentrations of 300-, 400- and 500 μg/ml. Standard antibiotic disc kanamycin (30μg/ml) was used for comparison. The minimum inhibitory concentration (MIC) of ethanolic extracts of the leaves of these medicinal plants were determined by testing the extracts on four Gram-positive and five Gram-negative bacteria by serial tube dilution method.   Results: All the extracts have notable antimicrobial activities against the test organisms. The ethanolic extracts of the leaves showed the highest antimicrobial activities against Bacillus megaterium and Shigella dysenteriae for An. paniculata, Ad. vasica and Al. vera; Bacillus subtilis and Salmonella typhi for C. roseus and N. arbortristis; Staphylociccus aureus and Salmonella typhi for V. vegundo; and Bacillus subtilis and Shigella sonnei for F. ramontchi respectively. The extract of the plants had MIC values ranging from 32 to 128 mg/ml. All plant extracts showed no MIC against Shigella shiga and against Sarcina lutea only C. roseus showed MIC 128 mg/ml.   Conclusion: The results revealed that the ethanolic extracts of the plants under present investigation have notable antimicrobial activities.   Keywords: medicinal plants; antimicrobial screening; MIC; bacteria. DOI: http://dx.doi.org/10.3329/jbs.v18i0.8788 JBS 2010; 18(0): 128-133

Lactate production by aerobic bacteria grown in cerebrospinal fluid.

1984 ◽  
Vol 30 (11) ◽  
pp. 1875-1876 ◽  
Author(s):  
F L Kiechle ◽  
M A Kamela ◽  
R W Starnes
Keyword(s):  
Cerebrospinal Fluid ◽  
Bacterial Meningitis ◽  
Lactate Concentration ◽  
Lactate Production ◽  
Aerobic Bacteria ◽  
Gram Negative Bacteria ◽  
High Concentration ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Abstract The source of the abnormally high concentration of lactate in the cerebrospinal fluid in patients with bacterial meningitis is not known. It may represent a bacterial metabolite. To determine whether cerebrospinal fluid possesses appropriate substrates to support the growth of pathogenic aerobic bacteria, three Gram-positive and nine Gram-negative bacteria were separately inoculated in pooled normal cerebrospinal fluid. After incubation for 24 h, all Gram-positive bacteria increased lactate, eight Gram-negative bacteria decreased lactate, and one Gram-negative bacteria failed to significantly change the lactate concentration. We conclude that lactate produced in cerebrospinal fluid in patients with aerobic bacterial meningitis is not necessarily a bacterial metabolite.

Characterization and identification of antimicrobial peptides with different functional activities

2019 ◽  
Vol 21 (3) ◽  
pp. 1098-1114 ◽  
Author(s):  
Chia-Ru Chung ◽  
Ting-Rung Kuo ◽  
Li-Ching Wu ◽  
Tzong-Yi Lee ◽  
Jorng-Tzong Horng
Keyword(s):  
Antimicrobial Peptides ◽  
Hot Spot ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Van Der Waals Volume ◽  
Gram Negative ◽  
Functional Activities ◽  
Wide Range ◽  
Anti Cancer ◽  
Anti Fungal

Abstract In recent years, antimicrobial peptides (AMPs) have become an emerging area of focus when developing therapeutics hot spot residues of proteins are dominant against infections. Importantly, AMPs are produced by virtually all known living organisms and are able to target a wide range of pathogenic microorganisms, including viruses, parasites, bacteria and fungi. Although several studies have proposed different machine learning methods to predict peptides as being AMPs, most do not consider the diversity of AMP activities. On this basis, we specifically investigated the sequence features of AMPs with a range of functional activities, including anti-parasitic, anti-viral, anti-cancer and anti-fungal activities and those that target mammals, Gram-positive and Gram-negative bacteria. A new scheme is proposed to systematically characterize and identify AMPs and their functional activities. The 1st stage of the proposed approach is to identify the AMPs, while the 2nd involves further characterization of their functional activities. Sequential forward selection was employed to extract potentially informative features that are possibly associated with the functional activities of the AMPs. These features include hydrophobicity, the normalized van der Waals volume, polarity, charge and solvent accessibility—all of which are essential attributes in classifying between AMPs and non-AMPs. The results revealed the 1st stage AMP classifier was able to achieve an area under the receiver operating characteristic curve (AUC) value of 0.9894. During the 2nd stage, we found pseudo amino acid composition to be an informative attribute when differentiating between AMPs in terms of their functional activities. The independent testing results demonstrated that the AUCs of the multi-class models were 0.7773, 0.9404, 0.8231, 0.8578, 0.8648, 0.8745 and 0.8672 for anti-parasitic, anti-viral, anti-cancer, anti-fungal AMPs and those that target mammals, Gram-positive and Gram-negative bacteria, respectively. The proposed scheme helps facilitate biological experiments related to the functional analysis of AMPs. Additionally, it was implemented as a user-friendly web server (AMPfun, http://fdblab.csie.ncu.edu.tw/AMPfun/index.html) that allows individuals to explore the antimicrobial functions of peptides of interest.

scholarly journals DETERMINATION OF ANTIBACTERIAL ACTIVITY OF SOME IMPORTANT SPICES

2015 ◽  
Vol 3 (10) ◽  
pp. 57-64
Author(s):  
Ranganathan Kapilan
Keyword(s):  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Pathogenic Bacteria ◽  
Maximum Activity ◽  
Gram Negative Bacteria ◽  
Alcoholic Extract ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Wide Range

Wide range of plant extracts are used for medicinal purposes as they are very cheap, efficient, harmless and do not cause any side effects. Spices are parts of different plants and they add special aroma and taste to the food preparations. The aim of the study was to determine the antimicrobial activity of some important naturally grown spices against gram positive and gram negative pathogenic bacteria. Antibacterial activity of the spices was tested against gram positive bacteria Bacillus pumilus, Bacillus cereus and Staphylococcus aureus and gram negative bacteria Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa using aqueous, ethanolic, methanolic and liquid nutrient extracts. Among all the extracts tested alcoholic extracts of Cardamom (Elettaria cardamom), clove (Eugenia caryophyllus) and lemongrass (Cymbopogoncitratus) showed maximum antimicrobial activity against gram negative bacteria while alcoholic extract of Cardamom (Elettaria cardamom) and lemongrass (Cymbopogoncitratus) showed maximum activity against gram positive bacteria. All the spices tested in this study proved that they have antibacterial activity and the maximum activity index (1.39) was exhibited by the ethanol extract of cardamom against E.coli.

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