Identification and Characterization of Polyphenols from Carissa spinarum Fruit and Evaluation of Their Antioxidant and Anti-quorum Sensing Activity

Polyphenols and CRISPR as Quorum Quenching Agents in Antibiotic-Resistant Foodborne Human Pathogens (Salmonella Typhimurium, Campylobacter jejuni and Escherichia coli 0157:H7)

Antibiotic resistance in foodborne pathogens is an increasing threat to global human health. Among the most prevalent antibiotic-resistant bacteria are Salmonella enterica serovar Typhimurium, Campylobacter jejuni and E. coli 0157:H7. Control of these and other pathogens requires innovative approaches, i.e., discovering new molecules that will inactivate them, or render them less virulent without inducing resistance. Recently, several polyphenol molecules have been shown to possess such characteristics. Also, the use of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) approaches has recently been proposed for such purpose. This review summarizes the main findings regarding the application of both approaches to control the above-mentioned foodborne pathogens by relying on Quorum Sensing interference (Quorum Quenching) mechanisms and highlights the avenues needed for further research.

Polyphenols and CRISPR as Quorum Quenching Agents in Antibiotic-Resistant Foodborne Human Pathogens (Salmonella Typhimurium, Campylobacter jejuni and Escherichia coli 0157:H7)

Antibiotic resistance in foodborne pathogens is an increasing threat to global human health. Among the most prevalent antibiotic-resistant bacteria are Salmonella enterica serovar Typhimurium, Campylobacter jejuni and E. coli 0157:H7. Control of these and other pathogens requires innovative approaches, i.e., discovering new molecules that will inactivate them, or render them less virulent without inducing resistance. Recently, several polyphenol molecules have been shown to possess such characteristics. Also, the use of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) approaches has recently been proposed for such purpose. This review summarizes the main findings regarding the application of both approaches to control the above-mentioned foodborne pathogens by relying on Quorum Sensing interference (Quorum Quenching) mechanisms and highlights the avenues needed for further research.

Emerging trends in the inhibition of bacterial molecular communication: An overview

Quorum sensing (QS) is a molecular cell-cell communication utilized by several bacteria and some fungi. It involves cell density dependent gene expression that includes extra polymeric substance production, sporulation, antibiotic production, motility, competence, symbiosis and conjugation. These expressions were carried out by different signaling molecules like acyl homo-serine lactone (AHL) and auto-inducing peptides (AIPs) which was effluxed by gram negative and gram positive bacteria. Pathogenic bacteria and biofilms often exhibit high resistance to antibiotics, attributed to the presence of antibiotic efflux pumps, reduced membrane permeability, and enzymes that deactivate quorum sensing (QS) inhibitors. To counteract virulence and multi-drug resistance (MDR), novel strategies such as employing quorum sensing (QS) inhibitors and quorum quenchers are employed. It targets signaling molecules with synthesis and prevents the signal from binding to receptors. In this present review, the mechanisms of QS along with inhibitors from different sources are described. These strategies potentially interfere with QS and it can be applied in different fields, mainly in hospitals and marine environments where the pathogenic infections and biofilm formation are highly involved.

Evolving biofilm inhibition and eradication in clinical settings through plant-based antibiofilm agents

BACKGROUND

After almost 100 years since evidence of biofilm mode of growth and decades of intensive investigation about their formation, regulatory pathways and mechanisms of antimicrobial tolerance, nowadays there are still no therapeutic solutions to eradicate bacterial biofilms and their biomedical related issues.

PURPOSE

This review intends to provide a comprehensive summary of the recent and most relevant published studies on plant-based products, or their isolated compounds with antibiofilm activity mechanisms of action or identified molecular targets against bacterial biofilms. The objective is to offer a new perspective of most recent data for clinical researchers aiming to prevent or eliminate biofilm-associated infections caused by bacterial pathogens.

METHODS

The search was performed considering original research articles published on PubMed, Web of Science and Scopus from 2015 to April 2023, using keywords such as "antibiofilm", "antivirulence", "phytochemicals" and "plant extracts".

RESULTS

Over 180 articles were considered for this review with a focus on the priority human pathogens listed by World Health Organization, including Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Inhibition and detachment or dismantling of biofilms formed by these pathogens were found using plant-based extract/products or derivative compounds. Although combination of plant-based products and antibiotics were recorded and discussed, this topic is currently poorly explored and only for a reduced number of bacterial species.

CONCLUSIONS

This review clearly demonstrates that plant-based products or derivative compounds may be a promising therapeutic strategy to eliminate bacterial biofilms and their associated infections. After thoroughly reviewing the vast amount of research carried out over years, it was concluded that plant-based products are mostly able to prevent biofilm formation through inhibition of quorum sensing signals, but also to disrupt mature biofilms developed by multidrug resistant bacteria targeting the biofilm extracellular polymeric substance. Flavonoids and phenolic compounds seemed the most effective against bacterial biofilms.

Phytonutritional and Sensorial Assessment of a Novel Functional Beverage Formulated from an Underutilized Fruit of Carissa spinarum L

Carissa spinarum L. belongs to the family Apocynaceae. It is a native shrub of Asia, locally known as Karonda or Karanda, and is an underutilized crop throughout the Asian region. The Karonda fruit is a rich source of vitamin C, minerals, phenolics, antioxidants, flavonoids, and other biofunctional compounds. The lack of awareness and knowledge among the community results in the wastage of fruits. Therefore, the present research was designed to formulate an easy-to-prepare beverage drink using C. spinarum fruit to evaluate the nutritional potential of the undervalued Karonda fruit. A beverage drink was formulated with three pulp concentrations: 20, 30, and 40%, each having 12, 14, and 16 °Brix, respectively. A total of nine treatments were prepared and stored for up to 10 weeks in refrigerated storage. The physicochemical parameters, such as pH, titratable acidity, vitamin C, total sugars, anthocyanin, total phenolics, flavonoids, and antioxidants, were measured at two-week intervals from 0 to 10 weeks. Additionally, a sensory assessment of the beverage was conducted. A decreasing trend in titratable acidity was exhibited among all the treatments (from treatment 1 to treatment 9), with the values decreasing from 0.815 to 0.556 as the fruit concentration increased. On the other hand, an increasing trend was observed for pH (from 3.04 to 3.37), vitamin C (from 22.2 to 31.48), reducing and non-reducing sugars, anthocyanin (from 31.95 to 110), total phenolics (from 19.86 to 32.16), flavonoids (from 0.64 to 0.77), and antioxidants (from 48.8 to 67.6) from treatment 1 to treatment 9, respectively. The sensory studies of the beverage formulations revealed that treatment 9, which consisted of a 40% fruit base and 16 °Brix, was the most acceptable for further development of the beverage at a commercial scale. This study represents a novel scientific contribution toward the utilization of the undervalued fruit of C. spinarum L. for the development of a beverage product. Ultimately, it has the potential to address food insecurity issues worldwide while offering its associated health benefits.

Traditional Importance, Phytochemistry, Pharmacology, and Toxicological Attributes of the Promising Medicinal Herb Carissa spinarum L

Carissa spinarum L. (Apocynaceae), commonly known as Garna or Jungli Karonda, has a rich history of use in indigenous traditional medicinal systems owing to its tremendous medicinal and nutritional benefits. The present review aims to discuss the traditional uses, ethnopharmacology, bioactive composition, toxicity analysis, and biotechnological applications of Carissa spinarum L. (CS) to identify the gap between current applications and research conducted on this plant. We collected the literature published before December 2022 on the phytochemical composition, pharmacological properties, and biotechnological applications of CS. Literature in English from scientific databases such as Google Scholar, PubMed, ScienceDirect, Springer, and Wiley, along with books on CS, was analyzed and summarized to prepare this review. The plant taxonomy was verified using the “World Flora Online” database (http://www.worldfloraonline.org/). The in vitro and in vivo pharmacological studies on CS revealed its anthelmintic, anticonvulsant, anti-arthritic, anti-inflammatory, antimicrobial, antioxidant, antidiabetic, hepatoprotective, vasorelaxant, antihypertensive, antitumor, wound-healing, anti-venom, and antipyretic effects. Toxicological studies on CS also indicated the absence of any adverse effects even at high doses after oral administration. Although CS showed remarkable therapeutic activities against several diseases—such as diabetes, cancer, inflammation, and hepatitis B virus—there are several drawbacks in previous reports, including the lack of information on the drug dose, standards, controls, and mechanism of action of the extract or the phytocompounds responsible for its activity. Extensive research with proper in vivo or in vitro model systems is required to validate its reported activities.

Electrochemical Control of Biofilm Formation and Approaches to Biofilm Removal

This review deals with microbial adhesion to metal-based surfaces and the subsequent biofilm formation, showing that both processes are a serious problem in the food industry, where pathogenic microorganisms released from the biofilm structure may pollute food and related material during their production. Biofilm exhibits an increased resistance toward sanitizers and disinfectants, which complicates the removal or inactivation of microorganisms in these products. In the existing traditional techniques and modern approaches for clean-in-place, electrochemical biofilm control offers promising technology, where surface properties or the reactions taking place on the surface are controlled to delay or prevent cell attachment or to remove microbial cells from the surface. In this overview, biofilm characterization, the classification of bacteria-forming biofilms, the influence of environmental conditions for bacterial attachment to material surfaces, and the evaluation of the role of biofilm morphology are described in detail. Health aspects, biofilm control methods in the food industry, and conventional approaches to biofilm removal are included as well, in order to consider the possibilities and limitations of various electrochemical approaches to biofilm control with respect to potential applications in the food industry.

Associations between Frequency of Culinary Herb Use and Gut Microbiota

While evidence suggests that culinary herbs have the potential to modulate gut microbiota, much of the current research investigating the interactions between diet and the human gut microbiome either largely excludes culinary herbs or does not assess use in standard culinary settings. As such, the primary objective of this study was to evaluate how the frequency of culinary herb use is related to microbiome diversity and the abundance of certain taxa, measured at the phylum level. In this secondary data analysis of the INCLD Health cohort, we examined survey responses assessing frequency of culinary herb use and microbiome analysis of collected stool samples. We did not observe any associations between frequency of culinary herb use and Shannon Index, a measure of alpha diversity. Regarding the abundance of certain taxa, the frequency of use of polyphenol-rich herbs and herbs with certain quantities of antibacterial compounds was positively associated with Firmicutes abundance, and negatively associated with Proteobacteria abundance. Additionally, the total number of herbs used with high frequency, defined as over three times per week, was also positively associated with Firmicutes abundance, independent of adjustments, and negatively associated with Proteobacteria abundance, after adjusting for dietary factors. Frequency of culinary herb use was not associated with Bacteroidota or Actinobacteria abundance.

Alantolactone modulates the production of quorum sensing mediated virulence factors and biofilm formation in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen in immunocompromised patients and accounts for mortality worldwide. Quorum sensing (QS) and QS mediated biofilm formation of P. aeruginosa increase the severity of infection in the host. New and effective therapeutics are in high demand to eliminate Pseudomonas infections. The current study investigated the quorum quenching and biofilm inhibition properties of alantolactone (ATL) against P. aeruginosa PAO1. The production of key virulence factors and biofilm components were affected in bacteria when treated with sub-MIC of ATL and further validated by qRT-PCR studies. The anti-infective potential of ATL was corroborated in an in vivo model with improved survival of infected Caenorhabditis elegans and reduced bacterial colonization. In silico studies suggested the molecular interactions of ATL to QS proteins as stable. Finally, ATL was explored in the present study to inhibit QS pathways and holds the potential to develop into an effective anti-infective agent against P. aeruginosa.

Physicochemical Composition and Characterization of Bioactive Compounds of Mulberry (Morus indica L.) Fruit During Ontogeny

Mulberry fruit is well recognized as one of the richest sources of bioactive compounds. We investigated the physicochemical composition and characterized the bioactive compounds during different ripening stages of mulberry (Morus indica) fruit and evaluated their anti-quorum sensing activity on Chromobacterium violaceum. The proximate components such as carbohydrates, proteins and lipids were found to be high in the ripe fruit compared to unripe and mid-ripe fruit. The ripe fruit contained higher content of total phenolics and flavonoids (336.05 and 282.55 mg/100 g fresh weight (FW), respectively). Epicatechin and resveratrol were the major polyphenols detected in the fruit with the range 5.13-19.46 and 4.07-14.45 mg/100 g FW, respectively. Chlorogenic acid and myricetin were predominant in the unripe and mid-ripe fruit (7.14 and 1.84 mg/100 g FW, respectively). The fruit was found to be an excellent source of anti-diabetic compound 1-deoxynojirimycin. The highest content of 1-deoxynojirimycin was present in the mid-ripe fruit, with a content of 2.91 mg/100 g FW. Furthermore, fruit extracts exhibited anti-quorum sensing activity against Chromobacterium violaceum by effectively inhibiting violacein production. Ripe fruit extracts showed the highest activity of 76.30% at 1 mg/mL and thus, could be used as a potent anti-quorum sensing agent. The results could be promising in the selection of appropriate developmental stages for M. indica fruit commercial exploitation in the food formulations rich in potential health components.