Synthetic Ellagic Acid Glycosides Inhibit Early Stage Adhesion of Streptococcus agalactiae Biofilms as Observed by Scanning Electron Microscopy

Valorization of polyphenolic compounds from food industry by-products for application in polysaccharide-based nanoparticles

In the last decades, evidence has indicated the beneficial properties of dietary polyphenols. In vitro and in vivo studies support that the regular intake of these compounds may be a strategy to reduce the risks of some chronic non-communicable diseases. Despite their beneficial properties, they are poorly bioavailable compounds. Thus, the main objective of this review is to explore how nanotechnology improves human health while reducing environmental impacts with the sustainable use of vegetable residues, from extraction to the development of functional foods and supplements. This extensive literature review discusses different studies based on the application of nanotechnology to stabilize polyphenolic compounds and maintain their physical-chemical stability. Food industries commonly generate a significant amount of solid waste. Exploring the bioactive compounds of solid waste has been considered a sustainable strategy in line with emerging global sustainability needs. Nanotechnology can be an efficient tool to overcome the challenge of molecular instability, especially using polysaccharides such as pectin as assembling material. Complex polysaccharides are biomaterials that can be extracted from citrus and apple peels (from the juice industries) and constitute promising wall material stabilizing chemically sensitive compounds. Pectin is an excellent biomaterial to form nanostructures, as it has low toxicity, is biocompatible, and is resistant to human enzymes. The potential extraction of polyphenols and polysaccharides from residues and their inclusion in food supplements may be a possible application to reduce environmental impacts and constitutes an approach for effectively including bioactive compounds in the human diet. Extracting polyphenolics from industrial waste and using nanotechnology may be feasible to add value to food by-products, reduce impacts on nature and preserve the properties of these compounds.

Evaluation of Polyphenolic Composition and Antimicrobial Properties of Sanguisorba officinalis L. and Sanguisorba minor Scop

The most widespread Sanguisorba species are Sanguisorba officinalis L. and Sanguisorba minor Scop. which are also found in the Romanian flora and classified as medicinal plants because of hemostatic, antibacterial, antitumor, antioxidant and antiviral activities. This study aimed to characterize and compare Sanguisorba species in order to highlight which species is more valuable according to phenolic profile and antimicrobial activity. Based on high-performance liquid chromatography equipped with photodiode array detection and mass spectrometry (electrospray ionization) (HPLC-DAD-MS (ESI⁺)) analysis, it was evident that the ethanol extract obtained from the leaves of S. minor Scop. contains the highest content of phenolic compounds at 160.96 mg/g p.s., followed by the flower and root extract (131.56 mg/g dw and 121.36 mg/g dw, respectively). While in S. officinalis, the highest amount of phenols was recorded in the root extract (127.06 mg/g), followed by the flower and leaves extract (102.31 mg/g and 81.09 mg/g dw, respectively). Our results show that among the two species, S. minor Scop. is richer in phenolic compounds compared with the S. officinalis L. sample. In addition, the antimicrobial potential of each plant organ of Sanguisorba species was investigated. The ethanol extract of S. minor Scop. leaves exhibited better antibacterial activity against all of the bacteria tested, especially on Staphylococcus aureus, with an inhibition zone of 15.33 ± 0.83 mm. Due to the chemical composition and antimicrobial effect, the Sanguisorba species can be used as food supplements with beneficial effects on human health.

Recent advances on human milk oligosaccharide antimicrobial activity

Over the past century, human health has been enhanced by antimicrobial development. Following the deployment of the first antibiotics in the 1940s, bacterial resistance evolved and has increasingly outmaneuvered even the most promising antimicrobial agents. Accordingly, increased interest has been placed on alternative methods to circumvent antimicrobial resistance evolution. In the enclosed short review, we discuss the antimicrobial properties of human breast milk with a special emphasis on human milk oligosaccharides (HMOs). We recount studies across gram-negative and gram-positive pathogens, highlighting the usage of HMOs in promoting human health and wellness.

Small Carbohydrate Derivatives as Potent Antibiofilm Agents

Biofilm formation by most pathogenic bacteria is considered as one of the key mechanisms associated with virulence and antibiotic resistance. Biofilm-forming bacteria adhere to the surfaces of biological or implant medical devices and create communities within their self-produced extracellular matrix that are difficult to treat by existing antibiotics. There is an urgent need to synthesize and screen structurally diverse molecules for their antibiofilm activity that can remove or minimize the bacterial biofilm. The development of carbohydrate-based small molecules as antibiofilm agents holds a great promise in addressing the problem of the eradication of biofilm-related infections. Owing to their structural diversity and specificity, the sugar scaffolds are valuable entities for developing antibiofilm agents. In this perspective, we discuss the literature pertaining to carbohydrate-based natural antibiofilm agents and provide an overview of the design, activity, and mode of action of potent synthetic carbohydrate-based molecules.

The applicability of pH-zone-refining counter-current chromatography for preparative separation of biosynthesis products: Glycosylation products as example

Biosynthesis is a research hot-spot in recent years, however, the purification of its final products is a tough work. Liquid stationary phase and large-scale separation ability of PZRCCC could easily avoid the commonly disadvantages occurred in traditional column chromatography. These characteristics makes PZRCCC particularly applicable for final products separation in biosynthesis. In this study, the glycosylation products of ellagic acid by one-pot glycosylation were successfully purified by PZRCCC to show the applicability of PZRCCC for preparative separation of biosynthesis products. An optimized ethyl acetate/n-buthanol/water (3:3:5, v/v/v) system was applied in this study, where 5 mM trifluoroacetic acid (TFA) as the retainer and 30 mM triethylamine (TEA) as the eluter were added. As a result, four ellagic acid glycosylation products, including 51 mg of ellagic acid-4, 3'-O-β-D-diglucoside (EG-1), 24 mg of ellagic acid-4, 4'-O-β-D-diglucoside (EG-2), 11 mg of ellagic acid-4-O-β-D-glucosyl (1→2)-β-D-glucoside (EG-3) and 64 mg of ellagic acid-4-O-β-D-glucoside (EG-4) were simultaneously separated from 500 mg of glycosylation crude products, with the purity of 93.3%, 91.2%, 89.4% and 95.5%, respectively. Their structures were identified by spectroscopic analysis.

Optimization of Streptococcus agalactiae Biofilm Culture in a Continuous Flow System for Photoinactivation Studies

Streptococcus agalactiae is a relevant cause of neonatal mortality. It can be transferred to infants via the vaginal tract and cause meningitis, pneumonia, arthritis, or sepsis, among other diseases. The cause of therapy ineffectiveness and infection recurrence is the growth of bacteria as biofilms. To date, several research teams have attempted to find a suitable medium for the cultivation of S. agalactiae biofilms. Among others, simulated vaginal fluid has been used; however, biofilm production in this medium has been found to be lower than that in tryptic soy broth. We have previously shown that S. agalactiae can be successfully eradicated by photoinactivation in planktonic culture, but there have been no studies on biofilms. The aim of this study was to optimize S. agalactiae biofilm culture conditions to be used in photoinactivation studies. We compared biofilm production by four strains representing the most common serotypes in four different broth media with crystal violet staining. Then, we evaluated stationary biofilm culture in microtiter plates and biofilm growth in a CDC Biofilm Reactor® (BioSurface Technologies, Bozeman, MT, USA) under continuous flow conditions. Subsequently, we applied Rose Bengal-mediated photoinactivation to both biofilm models. We have shown that photoinactivation is efficient in biofilm eradication and is not cyto/phototoxic to human keratinocytes. We found conditions allowing for stable and repetitive S. agalactiae biofilm growth in continuous flow conditions, which can be successfully utilized in photoinactivation assays and potentially in all other antibacterial studies.

Strategies and Approaches for Discovery of Small Molecule Disruptors of Biofilm Physiology

Biofilms, the predominant growth mode of microorganisms, pose a significant risk to human health. The protective biofilm matrix, typically composed of exopolysaccharides, proteins, nucleic acids, and lipids, combined with biofilm-grown bacteria’s heterogenous physiology, leads to enhanced fitness and tolerance to traditional methods for treatment. There is a need to identify biofilm inhibitors using diverse approaches and targeting different stages of biofilm formation. This review discusses discovery strategies that successfully identified a wide range of inhibitors and the processes used to characterize their inhibition mechanism and further improvement. Additionally, we examine the structure–activity relationship (SAR) for some of these inhibitors to optimize inhibitor activity.

Liposomal Ellagic Acid Alleviates Cyclophosphamide-Induced Toxicity and Eliminates the Systemic Cryptococcus neoformans Infection in Leukopenic Mice

Cryptococcus neoformans infections rose sharply due to rapid increase in the numbers of immunocompromised individuals in recent years. Treatment of Cryptococcosis in immunocompromised persons is largely very challenging and hopeless. Hence, this study aimed to determine the activity of ellagic acid (EA) in the treatment of C. neoformans in cyclophosphamide injected leukopenic mice. A liposomal formulation of ellagic acid (Lip-EA) was prepared and characterized, and its antifungal activity was assessed in comparison to fluconazole (FLZ). The efficacy of the drug treatment was tested by assessing survival rate, fungal burden, and histological analysis in lung tissues. The safety of the drug formulations was tested by investigating hepatic, renal function, and antioxidant levels. The results of the present work demonstrated that Lip-EA, not FLZ, effectively eliminated C. neoformans infection in the leukopenic mice. Mice treated with Lip-EA (40 mg/kg) showed 70% survival rate and highly reduced fungal burden in their lung tissues, whereas the mice treated with FLZ (40 mg/kg) had 20% survival rate and greater fungal load in their lungs. Noteworthy, Lip-EA treatment alleviated cyclophosphamide-induced toxicity and restored hepatic and renal function parameters. Moreover, Lip-EA treatment restored the levels of superoxide dismutase and reduced glutathione and catalase in the lung tissues. The effect of FLZ or EA or Lip-EA against C. neoformans infection was assessed by the histological analysis of lung tissues. Lip-EA effectively reduced influx of inflammatory cells, thickening of alveolar walls, congestion, and hemorrhage. The findings of the present study suggest that Lip-EA may prove to be a promising therapeutic formulation against C. neoformans in immunocompromised persons.

Leveraging Stereoelectronic Effects in Biofilm Eradication: Synthetic β-Amino Human Milk Oligosaccharides Impede Microbial Adhesion As Observed by Scanning Electron Microscopy

Alongside Edward, Lemieux was among the earliest researchers studying negative hyperconjugation (i.e., the anomeric effect) or the preference for gauche conformations about the C1-O5 bond in carbohydrates. Lemieux also studied an esoteric, if not controversial, theory known as the reverse anomeric effect (RAE). This theory is used to rationalize scenarios where predicted anomeric stabilization does not occur. One such example is the Kochetkov amination where reducing end amines exist solely as the β-anomer. Herein, we provide a brief account of Lemieux's contributions to the field of stereoelectronics and apply this knowledge toward the synthesis of β-amino human milk oligosaccharides (βΑ-HMOs). These molecules were evaluated for their ability to inhibit growth and biofilm production in Group B Streptococcus (GBS) and Staphylococcus aureus. While the parent HMOs lacked antimicrobial and antibiofilm activity, their β-amino derivatives significantly inhibited biofilm formation in both species. Field emission gun-scanning single electron microscopy (FEG-SEM) revealed that treatment with β-amino HMOs significantly inhibits bacterial adherence and eliminates the ability of both microbes to form biofilms.