Objective: To investigate the effect of (i) seed extracts of Pongamia pinnata, Pyrus pyrifolia, and Manilkara hexandra, (ii) bacterial pigment prodigiosin, and (iii) three organic solvents (ethanol, methanol, and DMSO), on quorum sensing (QS) in Chromobacterium violaceum.
Methods: C. violaceum was challenged with plant extracts prepared by microwave assisted extraction (MAE) method, prodigiosin, and organic solvents. Effect of these test substances on C. violaceum growth, and quorum sensing regulated pigment (violacein) production was studied by broth dilution assay. High performance liquid chromatography (HPLC) was also applied to generate chromatographic fingerprint of the active extracts. Effect of sub-MIC level of the antibiotic streptomycin on quorum sensing regulated pigment production was also studied.
Results: P. pinnata seed extracts and prodigiosin were found to possess anti-QS, and M. hexandra and P. pyrifolia seed extracts to possess QS-enhancing effect in C. violaceum. DMSO was found to enhance violacein production, whereas ethanol and methanol reduced violacein production in C. violaceum. Streptomycin at sub-MIC level was able to significantly arrest QS-regulated pigment production in C. violaceum and S. marcescens.
Conclusion: Prodigiosin and the seed extracts used in this study could affect quorum sensing in C. violaceum to a notable extent. Results of this study also emphasizes the importance of inclusion of appropriate solvent controls (negative controls) in bioassays designed for screening of antimicrobial and/or anti-QS compounds. Antipathogenic potential of low concentrations of streptomycin was also demonstrated.
Table of Contents
1. INTRODUCTION
2. MATERIALS AND METHODS
2.1 Plant material
2.2 Test organisms
2.3 Microwave Assisted Extraction (MAE)
2.4 Inoculum standardization
2.5 Antimicrobial susceptibility testing (AST) with planktonic cells (Macrobroth Dilution method)
2.6 Quantification of Violacein
3. Results
3.1 The extraction efficiency and reconstitution efficiency of various extracts of all the seeds are shown in Table1.
3.2 Anti-quorum sensing activities in P. Pinnata plant using Antimicrobial susceptibility testing of organism
3.3 Anti-quorum sensing activities of prodigiosin
3.4 Quorum sensing enhancing activities in M. hexandra and P. pyrifolia plants using Antimicrobial susceptibility testing of organism
4. Discussion
Research Objective and Topics
This study aims to investigate the potential of medicinal plants as sources of quorum-sensing inhibitors (QSIs) and quorum-sensing enhancers. By testing extracts from selected plants against the bacterium Chromobacterium violaceum, the research seeks to validate the traditional medicinal use of these plants and explore their pharmacological applications in combating bacterial infections and managing virulence factors.
- Screening of medicinal plant species for anti-quorum sensing and quorum-sensing enhancing activities.
- Evaluation of microwave-assisted extraction (MAE) efficiency using different polar and non-polar solvents.
- Assessment of bacterial growth and violacein production as indicators of quorum sensing modulation.
- HPLC analysis of plant extracts to identify active compounds responsible for quorum sensing effects.
- Examination of dose-dependent responses of bacterial virulence factors to varying concentrations of plant extracts.
Excerpt from the Book
1. INTRODUCTION
Nature has been a source of medicinal agents for thousands of years since it comprises of compounds that are highly diverse and often provide highly specific biological activities. This follows from the proposition that essentially all natural products have some receptor binding capacity (Verdine GL., 1996).To promote the proper use of herbal medicine and to determine their potential as sources for new drugs, it is essential to study medicinal plants, which have folklore reputation in a more intensified way( Awadh NA et al., 2001).
Some natural products have been approved as new antimicrobial drugs, but there is a continuous and urgent need to screen more and more plant species and discover new antimicrobial compounds with diverse chemical structures and novel mechanisms of action to combat new and re‐emerging infectious diseases of today’s era( Rojas R et al.,2003). Plant based natural constituents can be derived from any part of the plant like bark, leaves, lowers, roots, fruits, seeds, etc( Gordon MC et al., 2001).i.e. any part of the plant may contain active components. World Health Organization has also approved the study of medicinal plants for the development of new drug lead (WHO, 2000).
There is an evolving group of chronic infectious diseases and condition in which bacteria is present and they are difficult to culture and demonstrate consistently hence resistant to current antimicrobial and tools and often require surgical removal to resolve. Despite adequate drainage antibiotics are not the “silver bullet” once envisaged for this chronic infectious condition (Hayes GW et at., 1993). The use of antimicrobials from natural sources could have been a great impact for preserving food storage from contamination, and in controlling plant and human diseases of microbial origin (Balandrin et al., 1985).The continued evolution of infectious disease and the resistance offered by the pathogens to the existing pharmaceuticals have led to an intensified search for the new availability of antimicrobials against fungal, bacterial and viral particles as plants constantly interact with the rapidly changing and damaging environmental conditions.
Summary of Chapters
1. INTRODUCTION: Provides the background on medicinal plants as sources for new drugs and defines the role of quorum sensing in bacterial pathogenicity and the need for anti-QS alternatives.
2. MATERIALS AND METHODS: Details the collection, authentication, and processing of plant materials, including the microwave-assisted extraction (MAE) process, and describes the microbiological protocols for testing anti-quorum sensing activity.
3. Results: Presents the findings regarding extraction efficiencies and the specific results from anti-quorum sensing and quorum-sensing enhancing assays for the tested plants and solvents.
4. Discussion: Synthesizes the experimental findings, proposing that the identified QS-modulating effects contribute to the medicinal efficacy of the studied plants and suggests further clinical potential.
Keywords
Quorum sensing, medicinal plants, antimicrobial, Pongamia pinnata, Manilkara hexandra, Pyrus pyrifolia, Chromobacterium violaceum, violacein, microwave-assisted extraction, virulence factors, bioactive agents, ethnopharmacology, secondary metabolites.
Frequently Asked Questions
What is the fundamental focus of this research?
The work focuses on identifying medicinal plants that contain bioactive compounds capable of modulating bacterial quorum sensing, either by inhibiting it or enhancing it, to address the challenge of antibiotic resistance.
What are the primary thematic areas covered?
The main themes include plant-based drug discovery, bacterial cell-to-cell communication (quorum sensing), microbiological assay development, and the chemical extraction of plant secondary metabolites.
What is the primary goal of the study?
The primary goal is to validate the traditional use of specific medicinal plants by demonstrating their ability to interfere with or regulate virulence pathways in pathogenic bacteria, specifically Chromobacterium violaceum.
Which scientific methods are utilized?
The study employs microwave-assisted extraction (MAE), spectrophotometric quantification of violacein, bacterial macrobroth dilution methods for antimicrobial susceptibility testing, and high-performance liquid chromatography (HPLC) for chemical profile analysis.
What does the main body of the work cover?
The main body details the preparation of plant extracts using different solvents, the experimental setup for testing quorum-sensing modulation in C. violaceum, and a comprehensive presentation and analysis of the resulting quantitative data.
Which keywords characterize this research?
Key terms include quorum sensing, medicinal plants, antimicrobial, Pongamia pinnata, Manilkara hexandra, Pyrus pyrifolia, Chromobacterium violaceum, and bioactive secondary metabolites.
How does Pongamia pinnata affect bacterial quorum sensing according to the study?
The study found that the ethanolic and methanolic extracts of Pongamia pinnata seeds exhibit the highest anti-quorum sensing activity, significantly inhibiting violacein production in a dose-dependent manner.
What did the researchers discover regarding solvent efficiency?
The research concluded that polar solvents, particularly ethanol, were generally more effective than non-polar solvents like acetone for the extraction of the bioactive components responsible for the observed quorum-sensing effects.
What unique effect was observed with M. hexandra and P. pyrifolia?
Unlike P. pinnata, extracts from M. hexandra and P. pyrifolia were found to have quorum-sensing enhancing properties, leading to an increase in violacein production in the test organism.
- Quote paper
- Assistant Professor Vijay Kothari (Author), Haren Gosai (Author), Shreya Raval (Author), Vimla Chaudhary (Author), 2014, Natural products as potential sources of inhibitors of bacterial quorum-sensing, Munich, GRIN Verlag, https://www.grin.com/document/286836
