Bromelain and Nisin: The Natural Antimicrobials with High Potential in Biomedicine

Infectious diseases along with various cancer types are among the most significant public health problems and the leading cause of death worldwide. The situation has become even more complex with the rapid development of multidrug-resistant microorganisms. New drugs are urgently needed to curb the increasing spread of diseases in humans and livestock. Promising candidates are natural antimicrobial peptides produced by bacteria, and therapeutic enzymes, extracted from medicinal plants. This review highlights the structure and properties of plant origin bromelain and antimicrobial peptide nisin, along with their mechanism of action, the immobilization strategies, and recent applications in the field of biomedicine. Future perspectives towards the commercialization of new biomedical products, including these important bioactive compounds, have been highlighted.

Effect of Trachyspermum ammi essential oil, fractions and its derivatives on resistant fungal Strains

Persistentantimicrobial drugs treatmenthas resulted in antimicrobial resistance in fungi. There is always a gap for newer antifungal agent. As fungi are associated with multiple health risks in humans and many diseases in crops as well.Objective: To find alternate natural antimicrobial agent as compared to the synthetic one. Method:Essential oil of Trachyspermumammi was isolated, fractionated, and subjected to GC-MS analysis. Components from fractions were derivatized to check their antimicrobial potential against fungal resistant strains. Results:Analysis showed γ -terpinene (39%), α-phellandrene (1.3%), α-pinene (0.5%), Sabinene (0.15%), β-pinene (4.40%), β-myrcene (1.14%), O-cymene (15.78%), p-cymefne (38.78%), and other components were less than 1%. Fractional components were derivatised and their antifungal action was studied. Conclusion: Ajwain oil components found to be good against resistant fungal strains. While some derivatives showed more and some less antimicrobial action.

Lactic Acid Bacteria as Antimicrobial Agents: Food Safety and Microbial Food Spoilage Prevention

In the wake of continual foodborne disease outbreaks in recent years, it is critical to focus on strategies that protect public health and reduce the incidence of foodborne pathogens and spoilage microorganisms. Currently, there are limitations associated with conventional microbial control methods, such as the use of chemical preservatives and heat treatments. For example, such conventional treatments adversely impact the sensorial properties of food, resulting in undesirable organoleptic characteristics. Moreover, the growing consumer advocacy for safe and healthy food products, and the resultant paradigm shift toward clean labels, have caused an increased interest in natural and effective antimicrobial alternatives. For instance, natural antimicrobial elements synthesized by lactic acid bacteria (LAB) are generally inhibitory to pathogens and significantly impede the action of food spoilage organisms. Bacteriocins and other LAB metabolites have been commercially exploited for their antimicrobial properties and used in many applications in the dairy industry to prevent the growth of undesirable microorganisms. In this review, we summarized the natural antimicrobial compounds produced by LAB, with a specific focus on the mechanisms of action and applications for microbial food spoilage prevention and disease control. In addition, we provide support in the review for our recommendation for the application of LAB as a potential alternative antimicrobial strategy for addressing the challenges posed by antibiotic resistance among pathogens.

A study of The use of Manuka Honey and Methylglyoxal to Impart Antimicrobial Activity to Wool Textiles and Polymers

<p><b>Methylglyoxal (MGO), which is an ingredient in New Zealand Manuka honey (MH) possesses unique antimicrobial properties against a broad range of bacteria. MGO has been determined to have a low minimum inhibitory concentration against bacteria. This provides a new opportunity to develop the use of this compound as a natural antimicrobial agent to impart such antimicrobial properties to wool textiles. This is the focus and detailed research work of this thesis. Also, its application to paper and polymer surfaces has been investigated briefly.</b></p> <p>Due to their protein-based structure and porosity, woollen textiles provide a hospitable host for the growth of microorganisms. This microbial growth on such textiles can pose an undesirable health risk to humans and can negatively affect textile sales. the textile market. Similarly, microbial growth on other substrates such as walls, floors and various equipment can also pose health risks. There are a number of antimicrobial treatments on the market, but with the move to more natural-based antimicrobial agents, there is an opportunity to capture the natural antimicrobial properties of MH and particularly the active ingredient MGO, as a natural antimicrobial agent in wool textiles and paper and polymer substrates.</p> <p>This research developed a novel approach and methodology to incorporate MH and also MGO itself as an isolated component and antimicrobial agent of MH, into the wool fibres and chemically bonding it to the fibre proteins. This approach commenced with determining the extent of uptake of MH, based on its MGO concentration, and MGO itself into wool fibres. The extent of MH and MGO uptake has been determined with High-Performance Liquid Chromatography (HPLC). This uptake was studied over a range of MH and MGO concentrations and temperatures using loose top wool, yarn and finished wool fabric. An increase in temperature from room temperature up to 80 °C resulted in significantly higher amounts of MGO and MH being absorbed by the wool. Also, higher concentrations of the initial MGO and MH solutions accelerated the uptake rates and resulted in higher uptake amounts. The relatively slow diffusion rate of MGO into the wool necessarily required a long period of time, up to 14 days, for the particular uptake to generally reach the saturation level. The maximum amounts of MH and MGO that were incorporated into wool fibres in this study were 21.2 mg g-1 and 299 mg g-1 wool, respectively.</p> <p>The chemical interactions between MGO and MGO in MH with the wool fibres have been characterised by Fourier-Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). FTIR spectra showed that the MGO absorption by the wool changed the intensity of particular peaks between 2,000 and 700 cm-1 characteristic of the wool proteins, and the NH stretching peaks of the wool at 3,270 cm-1. The TGA and DSC analyses showed a thermal stability of the wool after MGO absorption and the likely formation of new bonds, probably H-bonds, between the MGO and the wool. Confirming these findings, the MGOWool and MH-Wool showed a resistance against MGO leaching on washing with water, where less than 1% (relative) of MGO leached out. These results suggest the MGO is likely chemically bound to the wool fibres through hydrogen bonding.</p> <p>The MGO-Wool and also MGO-paper composites produced in a similar way with MGO-Wool, exhibited antimicrobial activities against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). The MGO-Wool showed bacteriostatic properties for all composites even after three months of being synthesised. This opens up potential applications for the use of MH and MGO in antimicrobial woollen apparel, medical textiles and bandages.</p> <p>In addition, MGO was incorporated into samples of an acrylic polymer NeoCryl® XK-98 and a polyurethane, Kamthane K-5000, polymer resin, respectively. The interaction of MGO with the respective polymer chains resulted in similar hydrogen bonding between MGO and the polymers. At high MGO concentrations this bonding was confirmed by the presence of a new endothermic peak in the DSC pattern. The addition of MGO also modified the polymer surface and resulted in a more hydrophobic surface with an increased water droplet contact angle of 87.5°. The new polymer compositeswere successfully tested against S. aureus and E. coli microbes and were shown to exhibit antimicrobial properties.</p>

A study of The use of Manuka Honey and Methylglyoxal to Impart Antimicrobial Activity to Wool Textiles and Polymers

<p><b>Methylglyoxal (MGO), which is an ingredient in New Zealand Manuka honey (MH) possesses unique antimicrobial properties against a broad range of bacteria. MGO has been determined to have a low minimum inhibitory concentration against bacteria. This provides a new opportunity to develop the use of this compound as a natural antimicrobial agent to impart such antimicrobial properties to wool textiles. This is the focus and detailed research work of this thesis. Also, its application to paper and polymer surfaces has been investigated briefly.</b></p> <p>Due to their protein-based structure and porosity, woollen textiles provide a hospitable host for the growth of microorganisms. This microbial growth on such textiles can pose an undesirable health risk to humans and can negatively affect textile sales. the textile market. Similarly, microbial growth on other substrates such as walls, floors and various equipment can also pose health risks. There are a number of antimicrobial treatments on the market, but with the move to more natural-based antimicrobial agents, there is an opportunity to capture the natural antimicrobial properties of MH and particularly the active ingredient MGO, as a natural antimicrobial agent in wool textiles and paper and polymer substrates.</p> <p>This research developed a novel approach and methodology to incorporate MH and also MGO itself as an isolated component and antimicrobial agent of MH, into the wool fibres and chemically bonding it to the fibre proteins. This approach commenced with determining the extent of uptake of MH, based on its MGO concentration, and MGO itself into wool fibres. The extent of MH and MGO uptake has been determined with High-Performance Liquid Chromatography (HPLC). This uptake was studied over a range of MH and MGO concentrations and temperatures using loose top wool, yarn and finished wool fabric. An increase in temperature from room temperature up to 80 °C resulted in significantly higher amounts of MGO and MH being absorbed by the wool. Also, higher concentrations of the initial MGO and MH solutions accelerated the uptake rates and resulted in higher uptake amounts. The relatively slow diffusion rate of MGO into the wool necessarily required a long period of time, up to 14 days, for the particular uptake to generally reach the saturation level. The maximum amounts of MH and MGO that were incorporated into wool fibres in this study were 21.2 mg g-1 and 299 mg g-1 wool, respectively.</p> <p>The chemical interactions between MGO and MGO in MH with the wool fibres have been characterised by Fourier-Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). FTIR spectra showed that the MGO absorption by the wool changed the intensity of particular peaks between 2,000 and 700 cm-1 characteristic of the wool proteins, and the NH stretching peaks of the wool at 3,270 cm-1. The TGA and DSC analyses showed a thermal stability of the wool after MGO absorption and the likely formation of new bonds, probably H-bonds, between the MGO and the wool. Confirming these findings, the MGOWool and MH-Wool showed a resistance against MGO leaching on washing with water, where less than 1% (relative) of MGO leached out. These results suggest the MGO is likely chemically bound to the wool fibres through hydrogen bonding.</p> <p>The MGO-Wool and also MGO-paper composites produced in a similar way with MGO-Wool, exhibited antimicrobial activities against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). The MGO-Wool showed bacteriostatic properties for all composites even after three months of being synthesised. This opens up potential applications for the use of MH and MGO in antimicrobial woollen apparel, medical textiles and bandages.</p> <p>In addition, MGO was incorporated into samples of an acrylic polymer NeoCryl® XK-98 and a polyurethane, Kamthane K-5000, polymer resin, respectively. The interaction of MGO with the respective polymer chains resulted in similar hydrogen bonding between MGO and the polymers. At high MGO concentrations this bonding was confirmed by the presence of a new endothermic peak in the DSC pattern. The addition of MGO also modified the polymer surface and resulted in a more hydrophobic surface with an increased water droplet contact angle of 87.5°. The new polymer compositeswere successfully tested against S. aureus and E. coli microbes and were shown to exhibit antimicrobial properties.</p>

Antimicrobial Properties of Chitosan and Chitosan Derivatives in the Treatment of Enteric Infections

Antibiotics played an important role in controlling the development of enteric infection. However, the emergence of antibiotic resistance and gut dysbiosis led to a growing interest in the use of natural antimicrobial agents as alternatives for therapy and disinfection. Chitosan is a nontoxic natural antimicrobial polymer and is approved by GRAS (Generally Recognized as Safe by the United States Food and Drug Administration). Chitosan and chitosan derivatives can kill microbes by neutralizing negative charges on the microbial surface. Besides, chemical modifications give chitosan derivatives better water solubility and antimicrobial property. This review gives an overview of the preparation of chitosan, its derivatives, and the conjugates with other polymers and nanoparticles with better antimicrobial properties, explains the direct and indirect mechanisms of action of chitosan, and summarizes current treatment for enteric infections as well as the role of chitosan and chitosan derivatives in the antimicrobial agents in enteric infections. Finally, we suggested future directions for further research to improve the treatment of enteric infections and to develop more useful chitosan derivatives and conjugates.

The Silkworm as a Source of Natural Antimicrobial Preparations: Efficacy on Various Bacterial Strains

The global spread of multi-resistant pathogens responsible for infections, which cannot be treated with existing drugs such as antibiotics, is of particular concern. Antibiotics are becoming increasingly ineffective and drug resistance is leading to more difficult-to-treat infections; therefore, new bioactive compounds with antimicrobial activity are needed and new alternative sources should be found. Antimicrobial peptides (AMPs) are synthesized by processes typical of the innate immune system and are present in almost all organisms. Insects are extremely resistant to bacterial infections as they can produce a wide range of AMPs, providing an effective first line of defense. The AMPs produced by insects therefore represent a possible source of natural antimicrobial molecules. In this paper, the possibility of using plasma preparations from silkworm (Bombyx mori) larvae as a source of antimicrobials was evaluated. After simple purification steps, insect plasma was analyzed and tested on different Gram-positive and Gram-negative bacterial strains. The results obtained are encouraging as the assays on Escherichia coli and Enterobacter cloacae showed significant decrease in the growth of these Gram-negative bacteria. Similar results were obtained on Gram-positive bacteria, such as Micrococcus luteus and Bacillus subtilis, which showed strong susceptibility to the silkworm AMPs pool. In contrast, Staphylococcus aureus displayed high resistance to Bombyx mori plasma. Finally, the tested plasma formulations were assessed for possible storage not only at 4 °C, but also above room temperature. In conclusion, partially purified plasma from silkworm could be a promising source of AMPs which could be used in formulations for topical applications, without additional and expensive purification steps.