Supercritical fluid extraction of four aromatic herbs and assessment of the volatile compositions, bioactive compounds, antibacterial, and anti-biofilm activity

Plant-derived bioactive compounds for the inhibition of biofilm formation: a comprehensive review

Biofilm formation is a widespread phenomenon that impacts different fields, including the food industry, agriculture, health care and the environment. Accordingly, there is a serious need for new methods of managing the problem of biofilm formation. Natural products have historically been a rich source of varied compounds with a wide variety of biological functions, including antibiofilm agents. In this review, we critically highlight and discuss the recent progress in understanding the antibiofilm effects of several bioactive compounds isolated from different plants, and in elucidating the underlying mechanisms of action and the factors influencing their adhesion. The literature shows that bioactive compounds have promising antibiofilm potential against both Gram-negative and Gram-positive bacterial and fungal strains, via several mechanisms of action, such as suppressing the formation of the polymer matrix, limiting O2 consumption, inhibiting microbial DNA replication, decreasing hydrophobicity of cell surfaces and blocking the quorum sensing network. This antibiofilm activity is influenced by several environmental factors, such as nutritional cues, pH values, O2 availability and temperature. This review demonstrates that several bioactive compounds could mitigate the problem of biofilm production. However, toxicological assessment and pharmacokinetic investigations of these molecules are strongly required to validate their safety.

Green extraction of Quercus infectoria gall with supercritical CO2 and methanol co-solvent

Green extraction of supercritical liquid CO2 (SCFE-CO2) using co-solvent methanol can produce a more complete phenolic acid composition and a higher quantity when compared to those without using co-solvent. The extract was devoid of toxicity. SCFE-CO2 is carried out by putting 100 g of Quercus infectoria gall of size 0.3 mm into extraction tube at temperature of 60 °C and the pressure of 20 MPa with a CO2 flow rate of 25 ml/min using co-solvent methanol with variation of flow speed 0.05, 0.5, 1.5, 3, and 6 for 60 min. The extract is analyzed using LC-MS/MS, the total phenolic content is determined using the Folin-Ceocateu method, and the toxicity value is determined using the Vero cell. According to the results, the green method of extracting SCFE-CO2 with methanol co-solvent can produce a peak and identify about 27 phenolic compounds, and increasing the rate of flow of methane co-solvent will greatly affect the outcome of the extraction to a flow rate of 0.5 ml/min, while adding a co-solvent with a flow speed above 0.5 does not affect the result. Repeated extraction of some of the largest phenolic peaks provide phenol content with minimal extract variability (div. sd. 0.1%), and the addition of soluble methanol will also increase the TPC concentration but does not increase the IC50 toxicity value above 1000.

Biomass-based micronutrient fertilizers and biofortification of raspberries fruits

The increasing amount of bio-waste creates the need to develop a method for efficient management based on processes that are more environmentally friendly than incineration and composting. This research aimed to utilize the waste of raspberry seeds after supercritical CO2 extraction. The biomass was enriched with micronutrients by the biosorption process to prepare micronutrient fertilizers for organic farming and biofortification of raspberries fruits. It was observed that at 100% dose of micronutrients, raspberry crop yield increased by 3%, and transfer of micronutrients to fruit biomass increased by 4.7%, 6.4%, and 8.8% (Cu, Mn, Zn, respectively) compared to commercial fertilizer. The supply of micronutrients at a dose of 150% led to a significant increase in micronutrient content of 3%, 41%, and 8% (Cu, Mn, and Zn, respectively) compared to commercial fertilizer. Research shows that the application of higher doses of micronutrients leads to the enrichment of edible parts of fruits, and fertilizers ensure environmental safety. The fruits contained on average 11.5% more microelements compared to the groups fertilized with the commercial product. The fruit yield (9.09-10.4 Mg per hectare) and the sugar content (9.82-10.2%) were also the highest. The micronutrients released from fertilizers and available to plants throughout the vegetation period affect the increase in yield, especially in the case of plants fruiting several times a year.

Characterization of effective phytochemicals in traditional Chinese medicine by mass spectrometry

Traditional Chinese medicines (TCMs) have been widely used in clinical and healthcare applications around the world. The characterization of the phytochemical components in TCMs is very important for studying the therapeutic mechanism of TCMs. In the analysis process, sample preparation and instrument analysis are key steps to improve analysis performance and accuracy. In recent years, chromatography combined with mass spectrometry (MS) has been widely used for the separation and detection of trace components in complex TCM samples. This article reviews various sample preparation techniques and chromatography-MS techniques, including the application of gas chromatography-MS and liquid chromatography-MS and other MS techniques in the characterization of phytochemicals in TCM materials and Chinese medicine products. This article also describes a new ambient ionization MS method for rapid and high-throughput analysis of TCM components.

Antiviral Characterization of Advanced Materials: Use of Bacteriophage Phi 6 as Surrogate of Enveloped Viruses Such as SARS-CoV-2

The bacteriophage phi 6 is a virus that belongs to a different Baltimore group than SARS-CoV-2 (group III instead of IV). However, it has a round-like shape and a lipid envelope like SARS-CoV-2, which render it very useful to be used as a surrogate of this infectious pathogen for biosafety reasons. Thus, recent antiviral studies have demonstrated that antiviral materials such as calcium alginate hydrogels, polyester-based fabrics coated with benzalkonium chloride (BAK), polyethylene terephthalate (PET) coated with BAK and polyester-based fabrics coated with cranberry extracts or solidified hand soap produce similar log reductions in viral titers of both types of enveloped viruses after similar viral contact times. Therefore, researchers with no access to biosafety level 3 facilities can perform antiviral tests of a broad range of biomaterials, composites, nanomaterials, nanocomposites, coatings and compounds against the bacteriophage phi 6 as a biosafe viral model of SARS-CoV-2. In fact, this bacteriophage has been used as a surrogate of SARS-CoV-2 to test a broad range of antiviral materials and compounds of different chemical natures (polymers, metals, alloys, ceramics, composites, etc.) and forms (films, coatings, nanomaterials, extracts, porous supports produced by additive manufacturing, etc.) during the current pandemic. Furthermore, this biosafe viral model has also been used as a surrogate of SARS-CoV-2 and other highly pathogenic enveloped viruses such as Ebola and influenza in a wide range of biotechnological applications.

Antioxidant, Antimicrobial and Antibiofilm Properties of Glechoma hederacea Extracts Obtained by Supercritical Fluid Extraction, Using Different Extraction Conditions

Glechoma hederacea var. longituba is a herbaceous plant from the Lamiaceae family, used in herbal medicine. In this work, we aimed to assess the total phenolic content, antioxidant, antimicrobial and antibiofilm activity of extracts obtained from G. hederacea via supercritical dioxide extraction with methanol as a co-solvent under different extraction conditions. The results showed that the activity of the obtained SC-CO2 extracts is strongly dependent on the extraction temperature. Significantly higher total polyphenol content, as well as antioxidant and antimicrobial activity towards bacteria and yeasts, was observed in the extract obtained at 40 °C, compared to extracts obtained at 50 °C and 60 °C; however, antifungal activity against filamentous fungi was not dependent on the extraction conditions. Antimicrobial activity also depended on the microorganism type. Higher sensitivity was exhibited by Gram-positive bacteria than by Gram-negative bacteria, with S. aureus and P. aeruginosa being the most sensitive species among each group. The most susceptible fungi were Candida albicans and Sclerotinia sclerotiorum. The antibiofilm activity was differentiated and depended on the extraction conditions, the microorganism and the method of biofilm treatment. All tested extracts inhibited biofilm formation, with the extract obtained at 40 °C showing the highest value, whereas only extract obtained at 60 °C efficiently removed mature biofilm.

Polyethylene Films Containing Plant Extracts in the Polymer Matrix as Antibacterial and Antiviral Materials

Low density polyethylene (LDPE) films covered with active coatings containing mixtures of rosemary, raspberry, and pomegranate CO₂ extracts were found to be active against selected bacterial strains that may extend the shelf life of food products. The coatings also offer antiviral activity, due to their influence on the activity of Φ6 bacteriophage, selected as a surrogate for SARS-CoV-2 particles. The mixture of these extracts could be incorporated into a polymer matrix to obtain a foil with antibacterial and antiviral properties. The initial goal of this work was to obtain active LDPE films containing a mixture of CO₂ extracts of the aforementioned plants, incorporated into an LDPE matrix via an extrusion process. The second aim of this study was to demonstrate the antibacterial properties of the active films against Gram-positive and Gram-negative bacteria, and to determine the antiviral effect of the modified material on Φ6 bacteriophage. In addition, an analysis was made on the influence of the active mixture on the polymer physicochemical features, e.g., mechanical and thermal properties, as well as its color and transparency. The results of this research indicated that the LDPE film containing a mixture of raspberry, rosemary, and pomegranate CO₂ extracts incorporated into an LDPE matrix inhibited the growth of Staphylococcus aureus. This film was also found to be active against Bacillus subtilis. This modified film did not inhibit the growth of Escherichia coli and Pseudomonas syringae cells; however, their number decreased significantly. The LDPE active film was also found to be active against Φ6 particles, meaning that the film had antiviral properties. The incorporation of the mixture of CO₂ extracts into the polymer matrix affected its mechanical properties. It was observed that parameters describing mechanical properties decreased, although did not affect the transition of LDPE significantly. Additionally, the modified film exhibited barrier properties towards UV radiation. Modified PE/CO₂ extracts films could be applied as a functional food packaging material with antibacterial and antiviral properties.

Polyethylene Films Coated with Antibacterial and Antiviral Layers Based on CO2 Extracts of Raspberry Seeds, of Pomegranate Seeds and of Rosemary

The main goal of the work was to create an internal coating based on super critical CO2 extracts of raspberry seeds, pomegranate seeds and rosemary that could be active against chosen bacterial strains. Additionally, the synergistic effect of these substances in the coating were then analysed. The next goal of the work was to demonstrate the antiviral activity of the coatings against phi6 bacteriophage particles (airborne viruses surrogate). The results of the study indicated that three coatings containing a mixture of extracts showed bacteriolytic activity against S. aureus cells and bacteriostatic activity against E. coli and B. subtilis strains. Two coatings showed bacteriolytic activity against a P. syringae strain. As a result of the experiments, a synergistic effect was noted in the active additives/compounds in the coatings. These coatings may be used as internal coatings for packaging films to extend the shelf life of selected food products. All seven coatings may also be used as external coatings with antiviral activity, as these coatings demonstrated significant effects on the phi6 phage, selected as a surrogate for airborne viruses, e.g., coronaviruses. It could be concluded that coatings I–VII will also show antiviral effects on SARS-CoV-2 particles.

Stabilization of water-in-oil emulsion of Pulicaria jaubertii extract by ultrasonication: Fabrication, characterization, and storage stability

This study investigated the effect of ultrasonic treatments on the properties and stability of the water-in-oil (W/O) emulsion of Pulicaria jaubertii (PJ) extract. The study used different ultrasound powers (0, 100, 200, 400, and 600 W) at two storage degrees (4 and 25 °C) for 28 days. The findings showed that the emulsifying properties were improved to different extents after ultrasonic treatments. The treatment at 600 W showed optimum particle size, polydispersity index, emulsifying property, viscosity properties, and release of total phenolic content than the other powers. However, the ultrasonic power of 400 W gave positive effects on creaming index and antioxidant release compared to 600 W. The emulsion stored at 4 °C presented higher stability than that stored at 25 °C during the 28 days of storage. Microscopically, the increase in sonication power up to 600 W reduced particle size and decreased flocculation, thus resulted in stable emulsions, which is desirable for its applications in food systems.