Pooja Patel

Bioactive Natural Products: An Overview, with Particular Emphasis on Those Possessing Potential to Inhibit Microbial Quorum Sensing

Bioactive natural products have formed the core of most ancient systems of healthcare and medicine. Crude natural preparations have been used for relief in a variety of infections and disease conditions. This review starts with a general description of the bioactive natural products, followed by the information on natural products being used for dealing with infectious microorganisms. In the latter section, much emphasis has been on the natural products capable of disrupting microbial communication, i.e., quorum sensing. Quorum sensing inhibitors are being expected to emerge as an important class of novel therapeutic agents in the future. Few other issues, important while performing lab experiments with natural products, are also touched upon.

Quorum sensing modulatory effect of sound stimulation on Serratia marcescens and Pseudomonas aeruginosa

Effect of nine different mono-frequency sound stimuli on two gram-negative bacteria (Pseudomonas aeruginosa and Serratia marcescens) was investigated. Frequency of the test sound ranged from 100 Hz to 2,000 Hz. Both the test bacteria responded differently to sonic stimulation. Sound corresponding to 600 HZ caused a notable reduction in quorum sensing (QS) regulated production of the pigment pyoverdine by P. aeruginosa. 400 Hz sound affected prodigiosin production by S. marcescens the most. 500 Hz sound could enhance prodigiosin production without affecting growth of the producing bacterium, suggesting the effect purely to be QS modulatory. This study has demonstrated the capacity of the sound waves of affecting bacterial growth and quorum sensing regulated metabolite production.

Sonic stimulation, and low power microwave radiation can modulate bacterial virulence towards Caenorhabditis elegans

Caenorhabditis elegans worms infected with different pathogenic bacteria were subjected to sonic treatment to investigate whether such sound treatment can exert any therapeutic effect on the infected worms. Sonic therapy corresponding to 400 Hz, and the divine sound ‘om’ were found to confer protective effect on this nematode worm in face of bacterial infection, particularly that caused by Serratia marcescens or Staphylococcus aureus. The observed effect seemed to occur due to influence of sound on bacteria, and not on the worm. In addition to this, effect of microwave exposure on bacterial virulence was also investigated, wherein microwave exposure was found to reduce virulence of S. aureus towards C. elegans.

Nanotechnological approaches to colon-specific drug delivery for modulating the quorum sensing of gut-associated pathogens

Abstract The human microbiome is increasingly being showed to have a direct and intimate relationship to human health and various disease conditions. Most of this microbiome is resident in the human gut, of which the colon is an important part. Microbial members of this gut community actively communicate among themselves through the process of quorum sensing (QS), and also with their human host. The level and nature of these communication processes play a crucial role in determining the overall health status, and susceptibility to various diseases, of the human system. Controlled modulation of QS-based and other communication processes within the human gut can prove to be a very effective tool in safeguarding human health. However, to achieve the full potential of any such approach, targeted delivery of QS-modulators specifically to the parts of human body, like the colon, which are characterized by high microbial density, is desired. Nanotechnological approaches can be of considerable use in such colon-specific delivery of potent QS-modulators, with lesser scope for degradation of any such therapeutic agents in their pre-colon journey.

Modulation of microbial quorum sensing: Nanotechnological approaches

Abstract Omnipresent microorganisms, though being mostly unicellular, can practice a collective behavior by executing a social activity called quorum sensing (QS). They communicate among themselves, and cross-kingdom communication is also widespread. The cross-talk between microbial members and their animal/plant host is important from a clinical and agricultural perspective. If we can learn to modulate these communication processes, downregulating them can be effective against pathogens; upregulating them can help increase the productivity of industrial fermentations, as many of the clinically and industrially relevant traits of microbes are QS-regulated. Nanotechnology seems to have the promise of target-specific delivery of QS modulators to the microbial population(s) in a diseased host, or inside a fermentor. Nanotechnology can help in achieving the desired QS-modulatory effects on target populations, using minimum concentrations of such formulations.

How Do Early Psychosis Services Define and Operationalize the Duration of Untreated Psychosis

Reducing the duration of untreated psychosis (DUP) is a key aim of early psychosis (EP) care. However, substantial variability in how the start and end points of DUP are defined impact its utility in clinical decision-making, and as an outcome measure. In this study, qualitative interviews were conducted with providers to assess how EP services and providers define, operationalize, and measure DUP. Twenty-five providers across 14 clinics were interviewed. Participants emphasized symptom frequency, conviction, distress caused, and impact when determining psychosis onset. DUP endpoint was typically identified as the first assessment in an episode of care that included an accurate diagnosis, leading to specialty EP treatment. Participants proposed a more structured operationalization of DUP, relative to those historically adopted in the literature. Integrating front-line provider perspectives could improve the accuracy of DUP measurement and address the heterogeneity in how the construct is operationalized across research and practice.

Anti-infective potential of a quorum modulatory polyherbal extract (panchvalkal) against certain pathogenic bacteria

Background In view of the gravity of the problem of antimicrobial resistance among pathogenic bacteria against conventional bactericidal agents, investigation on alternative approaches to combat bacterial infections is warranted. Objective Current study aimed at investigating anti-infective potential of a polyherbal ayurvedic formulation namely panchvalkal against three different pathogenic bacteria. Materials and methods The panchvalkal formulation available as Pentaphyte P5® was tested for its possible in vitro quorum-modulatory potential against Chromobacterium violaceum, Serratia marcescens, and Staphylococcus aureus through broth dilution assay. Invivo efficacy was demonstrated employing Caenorhabditis elegans as the model host for test pathogens. Results This formulation was found to exert quorum-modulatory effect on C. violaceum, S. marcescens, and S. aureus at 250–750 μg/ml. Besides altering production of the quorum sensing-regulated pigments in these bacteria, the test formulation also had in vitro effect on antibiotic susceptibility, catalase activity and haemolytic potential of the pathogens. Invivo assay confirmed the protective effect of this panchvalkal formulation on C. elegans, when challenged with the pathogenic bacteria. Repeated exposure of S. aureus to panchvalkal did not induce resistance in this bacterium. Conclusion To the best of our awareness, this the first report on quorum-modulatory potential of panchvalkal formulation, validating the anti-infective potential and moderate prebiotic property of this polyherbal preparation.

Anti-pathogenic efficacy of a polyherbal wound-care formulation (Herboheal) against Staphylococcus aureus, and identifying its molecular targets

BACKGROUND A polyherbal formulation (Herboheal) traditionally indicated for woundcare was investigated for its anti-virulence potential against the notorious pathogen Staphylococcus aureus. OBJECTIVE This study aimed at evaluating anti-virulence potential of Herboheal formulation against S. aureus in vitro as well as in vivo, followed by studying its effect on target bacteriums gene expression at the whole transcriptome level. METHODS In vitro efficacy of the test formulation was evaluated using broth dilution assay, whereas in vivo efficacy was assayed employing the nematode Caenorhabditis elegans as the model host. Molecular targets of the test formulation in S. aureus were elucidated through whole transcriptome analysis. RESULTS This formulation could exert inhibitory effect on bacterial growth and quorum sensingregulated pigment (staphyloxanthin) production at ≥ 0.025% v/v. It not only could inhibit S. aureus biofilm formation, but also eradicated pre-formed biofilm effectively. This formulation could modulate antibiotic susceptibility of S. aureus, enhanced its susceptibility to human serum heavily, while compromising its haemolytic potential. Herboheal-treated bacteria expressed notably lesser virulence towards the nematode worm Caenorhabditis elegans. Even repeated exposure of S. aureus to this polyherbal formulation did not give rise to resistant phenotype. Whole transcriptome analysis revealed genes associated with hemolysis, virulence, enzyme activity, transport, basic cellular processes, quorum sensing, and transcriptional regulators as the major targets of Herboheal in S. aureus. CONCLUSION This study validates the traditional use of Herboheal formulation in wound-care by demonstrating its efficacy against one of the pathogenic bacteria most commonly involved in wound infections.

Prophylactic potential of a Panchgavya formulation against certain pathogenic bacteria

A Panchgavya preparation was evaluated for its prophylactic efficacy against bacterial infection, employing the nematode worm Caenorhabditis elegans as a model host. Worms fed with the Panchgavya preparation prior to being challenged with pathogenic bacteria had a better survival rate against four out of five test bacterial pathogens, as compared to the control worms. Panchgavya feeding prior to bacterial challenge was found to be most effective against Staphylococcus aureus, resulting in 27% (p=0.0001) better worm survival. To the best of our awareness, this is the first report demonstrating in vivo prophylactic efficacy of Panchgavya mixture against pathogenic bacteria.

IMPORTANCE OF SELECTING APPROPRIATE WAVELENGTH, WHILE QUANTIFYING GROWTH AND PRODUCTION OF QUORUM SENSING REGULATED PIGMENTS IN BACTERIA.

BACKGROUND Pigment production is regulated by quorum-sensing (QS) in certain bacteria which are being widely used as model organisms in different QS labs. This paper emphasizes importance of selecting an appropriate wavelength for quantification of bacterial growth and pigmentation. While screening different natural/synthetic preparations for their possible QSmodulating potential, it becomes very much necessary to establish that the observed effect is truly QS-associated, and not falsely inflated owing to inaccurate quantification of bacterial cell density/ pigment intensity. METHODS Pigments were extracted in suitable organic solvents, whereas quantification of bacterial growth and extracted pigments was done photometrically. RESULTS Findings reported in this paper, suggest that while quantifying cell density in a pigmented bacterial suspension, such a wavelength (e.g. 764 nm) should be selected at which pigment interference is either absent or minimum. Additionally, importance of appropriate dilution of the bacterial cell suspensions, prior to photometric measurement has been highlighted. CONCLUSION This work indicates that while working with pigmented bacteria, it is important to pay attention to the absorption spectrum of the pigment(s) involved, and also to dilute the dense bacterial suspensions appropriately prior to measuring optical density, so as to avoid any major deviation of OD from the proportionality to the cell density. Besides presenting the experimental data in this paper, patents regarding measurement of cell growth, as well as those indicating the potential of commercialization of various aspects of QS research have been mentioned.