Interactions of resveratrol with other phenolics and activity against food-borne pathogens

Dietary anti-inflammatory and anti-bacterial medicinal plants and its compounds in bovine mastitis associated impact on human life

Bovine mastitis (BM) is the most common bacterial mediated inflammatory disease in the dairy cattle that causes huge economic loss to the dairy industry due to decreased milk quality and quantity. Milk is the essential food in the human diet, and rich in crucial nutrients that helps in lowering the risk of diseases like hypertension, cardiovascular diseases and type 2 diabetes. The main causative agents of the disease include various gram negative, and positive bacteria, along with other risk factors such as udder shape, age, genetic, and environmental factors also contributes much for the disease. Currently, antibiotics, immunotherapy, probiotics, dry cow, and lactation therapy are commonly recommended for BM. However, these treatments can only decrease the rise of new cases but can't eliminate the causative agents, and they also exhibit several limitations. Hence, there is an urgent need of a potential source that can generate a typical and ideal treatment to overcome the limitations and eliminate the pathogens. Among the various sources, medicinal plants and its derived products always play a significant role in drug discovery against several diseases. In addition, they are also known for its low toxicity and minimum resistance features. Therefore, plants and its compounds that possess anti-inflammatory and anti-bacterial properties can serve better in bovine mastitis. In addition, the plants that are serving as a food source and possessing pharmacological properties can act even better in bovine mastitis. Hence, in this evidence-based study, we particularly review the dietary medicinal plants and derived products that are proven for anti-inflammatory and anti-bacterial effects. Moreover, the role of each dietary plant and its compounds along with possible role in the management of bovine mastitis are delineated. In this way, this article serves as a standalone source for the researchers working in this area to help in the management of BM.

Unraveling the therapeutic efficacy of resveratrol in Alzheimer's disease: an umbrella review of systematic evidence

CONTEXT

Resveratrol (RV), a natural compound found in grapes, berries, and peanuts, has been extensively studied for its potential in treating Alzheimer's disease (AD). RV has shown promise in inhibiting the formation of beta-amyloid plaques (Aβ) and neurofibrillary tangles (NFTs), protecting against neuronal damage and oxidative stress, reducing inflammation, promoting neuroprotection, and improving the function of the blood-brain barrier (BBB). However, conflicting results have been reported, necessitating a comprehensive umbrella review of systematic reviews to provide an unbiased conclusion on the therapeutic effectiveness of RV in AD.

OBJECTIVE

The objective of this study was to systematically synthesize and evaluate systematic and meta-analysis reviews investigating the role of RV in AD using data from both human and animal studies.

DATA SOURCES AND EXTRACTION

Of the 34 systematic and meta-analysis reviews examining the association between RV and AD that were collected, six were included in this study based on specific selection criteria. To identify pertinent studies, a comprehensive search was conducted in English-language peer-reviewed journals without any restrictions on the publication date until October 15, 2023. The search was carried out across multiple databases, including Embase, MEDLINE (PubMed), Cochrane Library, Web of Science, and Google Scholar, utilizing appropriate terms relevant to the specific research field. The AMSTAR-2 and ROBIS tools were also used to evaluate the quality and risk of bias of the included systematic reviews, respectively. Two researchers independently extracted and analyzed the data, resolving any discrepancies through consensus. Of note, the study adhered to the PRIOR checklist.

DATA ANALYSIS

This umbrella review presented robust evidence supporting the positive impacts of RV in AD, irrespective of the specific mechanisms involved. It indeed indicated that all six systematic and meta-analysis reviews unanimously concluded that the consumption of RV can be effective in the treatment of AD.

CONCLUSION

RV exhibits promising potential for benefiting individuals with AD through various mechanisms. It has been observed to enhance cognitive function, reduce Aβ accumulation, provide neuroprotection, protect the BBB, support mitochondrial function, facilitate synaptic plasticity, stabilize tau proteins, mitigate oxidative stress, and reduce neuroinflammation commonly associated with AD.

Caffeic acid and ferulic acid can improve toxicological damage caused by iron overload mediated by carbonic anhydrase inhibition

The iron ion is an essential element for most forms of life, however, it can damage biological systems when found in free form. Chelation therapy is very important, but it is precarious. Caffeic and ferulic acid are antioxidant compounds with many properties described in research such as anti-inflammatory, antiobesogenic, antithrombotic, vasodilator, and anti-tumor. The aim of the study was to evaluate presenting an in silico approach on the toxicity and bioavailability of caffeic and ferulic acid, subsequently, evaluating them in an iron overload model in vivo and providing a pharmacophoric model through molecular docking. The predictive in silico test did not show relevant toxicity of the compounds, therefore, the in vivo test was performed. The rats received dextran iron and the test groups received caffeic and ferulic acid orally for six weeks. Biochemical, hematological parameters, and tissue oxidative stress marker were analyzed. The experimental model showed increased serum iron levels and changes in several serum parameters such as glucose (215.8 ± 20.3 mg/dL), ALT (512.2 ± 128.7 U/L), creatine kinase (186.8 ± 30.1 U/L), and creatine kinase isoform MB (373.3 ± 69.7 U/L). Caffeic acid and, to a lessed degree, ferullic acid, attenuated the effects of iron overload on the rat serum biochemical parameters. Docking showed a pharmacophoric model where carbonic anhydrase interacted with the test molecules and caffeic acid showed less energy expenditure in this interaction. The results illustrate a new therapeutic action of phenolic compounds on iron overload. The possible interference of carbonic anhydrase in iron metabolism needs to be elucidated.

Resveratrol-based biorefinery models for favoring its inclusion along the market value-added chains: A critical review

Resveratrol, a natural organic polyhydroxyphenolic compound, has gained significant attention in the last years given its potential health benefits, including antioxidant, anti-cancer, and anti-inflammatory properties. It can be directly extracted from plants, vegetables, and related products and waste resources, but also chemically/enzymatically/microbially synthesized. However, certain process strategies have some limitations, such as high costs, reduced yield or high energy demand, thus implying significant environmental loads. In this context, the search for more sustainable and circular process schemes is key to the integration of resveratrol into the market value chain of the food, cosmetic and pharmaceutical sectors. The extraction of resveratrol has traditionally been based on conventional methods such as solvent extraction, but advanced green extraction techniques offer more efficient and environmentally friendly alternatives. This review analyses both conventional and green alternative extraction technologies, as well as its bioproduction through microbial fermentation, in terms of production capacity, yield, purity and sustainability. It also presents alternative biorefinery models based on resveratrol bioproduction using by-products and waste streams as resources, specifically considering wine residues, peanut shells and wood bark as input resources, and also following a circular approach. This critical review provides some insight into the opportunities that resveratrol offers for promoting sustainable development and circularity in the related market value chains, and thus provides some criteria for decision making for biorefinery models in which resveratrol is one of the targeted high value-added products. It also identifies the future challenges to promote the inclusion of resveratrol in value chains, with the scale-up of green technologies and its demonstrated economic feasibility being the most prominent.

Antibacterial Activity of Essential Oils Combinations based on Thymus broussonnetii, and Their Synergism with some Antibiotics

The present study aimed to evaluate the antibacterial activity of the essential oil (EO) of Moroccan endemic Thymus broussonnetii alone, and in combination with EOs obtained from selected medicinal plants, namely Myrtus communis, Artemisia herba alba, Thymus pallidus, Thymus satureioides, Teucrium polium, and Rosmarinus officinalis. The synergistic interactions between the most effective combinations based on T. broussonnetii EO with two conventional antibiotics (streptomycin and ciprofloxacin) were also investigated. T. broussonnetii EO possessed a higher inhibitory activity against tested pathogenic bacteria with inhibition zone diameter (IZ) ranging from 21.61 ± 0.03 to 40.09 ± 0.02 mm, and MIC values between 0.140 mg/mL and 0.280 mg/mL. M. communis, A. herba alba, T. pallidus, T. satureioides, T. polium, and R. officinalis EOs showed moderate to weak antibacterial activity. Among tested EO mixtures, the highest synergistic antibacterial effect was recorded with the EO combination of T. broussonnetii and T. pallidus against S. aureus, E. coli, and S. enterica (FICI = 0.258). This EO combination was also the most effective mixture to synergistically enhance the antibacterial activity of the two antibiotics with up to a 128-fold increase, particularly against the gram-negative E. coli. These findings suggest that T. broussonnetii EO may be an interesting source of natural antimicrobials, for use in combination therapies with other plant EOs, and with conventional antimicrobial drugs to tackle the emergence of multidrug-resistant bacteria.

Antibiofilm potential of luteolin against multidrug-resistant Staphylococcus aureus isolated from dairy goats and farm environments

Staphylococcus aureus (S. aureus) is a prominent pathogen responsible for mastitis in dairy goats, and capable of contaminating farm environments. Luteolin is a naturally derived flavonoid found in many plant types. To our best of knowledge, this study involved the initial investigation into the prevalence of S. aureus and screened the multidrug-resistant (MDR) S. aureus from raw milk samples and farm environments. Furthermore, we explored the antimicrobial and antibiofilm activities of luteolin against MDR S. aureus. Antibiofilm activity was evaluated via crystal violet staining and confocal laser scanning microscopy (CLSM). Bacterial morphology and biofilm microstructure were observed via scanning electron microscopy (SEM), and the antibiofilm mechanisms were further explored based on extracellular polymeric substance (EPS) production, extracellular DNA (eDNA) content, and quantitative reverse transcription PCR (qRT-PCR). In total, 28 and 43 S. aureus isolates were isolated from raw milk and environmental samples, respectively. Raw milk samples had the highest prevalence of S. aureus (58.33%), followed by sewage sludge (35.42%), soil (27.78%), excrement (19.44%), bulk tank (12.50%), milking parlor (11.11%), and feed (7.50%). Among the isolated strains, 40 isolates (56.34%) expressed the MDR phenotype. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of luteolin against MDR S. aureus were 8-32 μg/mL and 16-64 μg/mL, respectively. Compared to that in the untreated control isolate, the number of dead cells increased, while the auto-aggregation and cell surface hydrophobicity decreased. Moreover, the cell membrane dissolved with the increase in luteolin concentration. Luteolin down-regulated the transcription of seven biofilm related genes: icaA, icaD, icab, hld, hla, agrA and RNAIII. These results indicated that S. aureus coexisted in raw milk and goat farm environments, and also suggested the potential of luteolin as a promising antibiofilm agent against MDR S. aureus.

In the Beginning Was the Bud: Phytochemicals from Olive (Olea europaea L.) Vegetative Buds and Their Biological Properties

Even though Olea europaea L. is one of the most important and well-studied crops in the world, embryonic parts of the plants remain largely understudied. In this study, comprehensive phytochemical profiling of olive vegetative buds of two Croatian cultivars, Lastovka and Oblica, was performed with an analysis of essential oils and methanol extracts as well as biological activities (antioxidant, antimicrobial, and cytotoxic activities). A total of 113 different volatiles were identified in essential oils with hydrocarbons accounting for up to 60.30% and (Z)-3-heptadecene being the most abundant compound. Oleacein, oleuropein, and 3-hydroxytyrosol had the highest concentrations of all phenolics in the bud extracts. Other major compounds belong to the chemical classes of sugars, fatty acids, and triterpenoid acids. Antioxidant, antimicrobial, and cytotoxic activities were determined for both cultivars. Apart from antioxidant activity, essential oils had a weak overall biological effect. The extract from cultivar Lastovka showed much better antioxidant activity than both isolates with both methods (with an oxygen radical absorbance capacity value of 1835.42 μM TE/g and DPPH IC₅₀ of 0.274 mg/mL), as well as antimicrobial activity with the best results against Listeria monocytogenes. The human breast adenocarcinoma MDA-MB-231 cell line showed the best response for cultivar Lastovka bud extract (IC₅₀ = 150 μg/mL) among three human cancer cell lines tested. These results demonstrate great chemical and biological potential that is hidden in olive buds and the need to increase research in the area of embryonic parts of plants.

Synthesis of active packaging films from Lepidium sativum gum/polyvinyl alcohol composites and their application in preserving cheddar cheese

The interest in active packaging for extending food shelf life has increased lately. Moreover, the negative impact of synthetic plastic wastes on the environmental motivated the researchers to seek for bio-based alternatives. In this context, active packaging film made of a composite composed of Lepidium sativum extract (LSE), polyvinyl alcohol (PVA), and a fixed amount of hyperbranched polyamide amine (PAMAM) were prepared. The chemical, thermal, and mechanical properties of the film were investigated. Moreover, we examined the extract's constituents and antioxidant properties. Cheddar cheese samples were coated with films of different compositions. The samples coated with active packaging films showed a longer preservation time of up to 4 weeks compared to other samples, which noticeably deteriorated. The films showed potent antimicrobial activity against five food-borne bacteria: three gram-negative bacteria including Escherichia coli O157.H7, Pseudomonas aeruginosa, and Salmonella Typhimurium, and two gram-positive bacteria, Listeria monocytogenes, and Staphylococcus aureus. Applying PVA films containing LSE improved the microbiological quality and delayed the visible decay of cheddar cheese. The oxidizability of the fat extracted from different cheese samples was 0.40-0.98, confirming oxidation resistance. Finally, cheese samples coated with treated films were protected from forming trans fats compared to other samples, demonstrating the effectiveness of modified films as antioxidant, antimicrobial, and food-preserving packaging.

Effects of Rubus fruticosus and Juniperus oxycedrus derivatives on culturability and viability of Listeria monocytogenes

The consumers' demand for safe foods without chemical additives increased the research for green solutions, based on natural antimicrobials. Plants can be an important source of bioactive compounds able to prevent the development of foodborne pathogens and spoilage microflora. This paper aimed to characterize phenolic extracts (PEs) and essential oils (EOs) obtained from Mediterranean Rubus fruticosus leaves and Juniperus oxycedrus needles and to evaluate their antimicrobial effects against Listeria monocytogenes Scott A. The growth dynamics with sub-lethal concentrations of plant derivatives were modeled and flow cytometry was used to better evidence the effect on cell viability and culturability. The results showed that these plant derivatives affected the growth of L. monocytogenes, increasing lag phase (about 40 h in the presence of PEs vs. 8 h in the control) and decreasing the final cell load of at least 1 log cycle with respect to the control. R. fruticosus EO was the most effective, determining an initial decrease of cell counts of about 6 log cycles, followed by a restart of growth after 10 h, with rate similar to the control (0.08 with R. fruticosus EO vs. 0.09 ((log CFU/ml)/h in the control) but significantly lower final cell load (7.33 vs. 8.92 log CFU/ml). According to flow cytometry, only R. fruticosus EO induced a relevant increase of dead cells, while the other plant derivatives determined different extent of sub-lethal cell injury. The discrepancy observed in some cases between viability and culturability could indicate the presence of cells not able to grow in culture media, whose fate needs to be further investigated to assess their potential recovery, thus bringing to an overestimation of the antimicrobial effect of these substances. This research contributed to increase the knowledge of these underused raw materials such as blackberry leaves and juniper needles that can be exploited in food and other industries.

Chemically Tuning Resveratrol for the Effective Killing of Gram-Positive Pathogens

In the era of antimicrobial resistance, the identification of new compounds with strong antimicrobial activity and the development of alternative therapies to fight drug-resistant bacteria are urgently needed. Here, we have used resveratrol, a safe and well-known plant-derived stilbene with poor antimicrobial properties, as a scaffold to design several new families of antimicrobials by adding different chemical entities at specific positions. We have characterized the mode of action of the most active compounds prepared and have examined their synergistic antibacterial activity in combination with traditional antibiotics. Some alkyl- and silyl-resveratrol derivatives show bactericidal activity against Gram-positive bacteria in the same low micromolar range of traditional antibiotics, with an original mechanism of action that combines membrane permeability activity with ionophore-related activities. No cross-resistance or antagonistic effect was observed with traditional antibiotics. Synergism was observed for some specific general-use antibiotics, such as aminoglycosides and cationic antimicrobial peptide antibiotics. No hemolytic activity was observed at the active concentrations or above, although some low toxicity against an MRC-5 cell line was noted.

Variations in the Composition, Antioxidant and Antimicrobial Activities of Cystoseira compressa during Seasonal Growth

The underexplored biodiversity of seaweeds has recently drawn great attention from researchers to find the bioactive compounds that might contribute to the growth of the blue economy. In this study, we aimed to explore the effect of seasonal growth (from May to September) on the in vitro antioxidant (FRAP, DPPH, and ORAC) and antimicrobial effects (MIC and MBC) of Cystoseira compressa collected in the Central Adriatic Sea. Algal compounds were analyzed by UPLC-PDA-ESI-QTOF, and TPC and TTC were determined. Fatty acids, among which oleic acid, palmitoleic acid, and palmitic acid were the dominant compounds in samples. The highest TPC, TTC and FRAP were obtained for June extract, 83.4 ± 4.0 mg GAE/g, 8.8 ± 0.8 mg CE/g and 2.7 ± 0.1 mM TE, respectively. The highest ORAC value of 72.1 ± 1.2 µM TE was obtained for the August samples, and all samples showed extremely high free radical scavenging activity and DPPH inhibition (>80%). The MIC and MBC results showed the best antibacterial activity for the June, July and August samples, when sea temperature was the highest, against Listeria monocytogenes, Staphylococcus aureus, and Salmonella enteritidis. The results show C. compressa as a potential species for the industrial production of nutraceuticals or functional food ingredients.

Phenolic-Rich Plant Extracts With Antimicrobial Activity: An Alternative to Food Preservatives and Biocides?

In recent years, the search for natural plant-based antimicrobial compounds as alternatives to some synthetic food preservatives or biocides has been stimulated by sanitary, environmental, regulatory, and marketing concerns. In this context, besides their established antioxidant activity, the antimicrobial activity of many plant phenolics deserved increased attention. Indeed, industries processing agricultural plants generate considerable quantities of phenolic-rich products and by-products, which could be valuable natural sources of natural antimicrobial molecules. Plant extracts containing volatile (e.g., essential oils) and non-volatile antimicrobial molecules can be distinguished. Plant essential oils are outside the scope of this review. This review will thus provide an overview of current knowledge regarding the promises and the limits of phenolic-rich plant extracts for food preservation and biofilm control on food-contacting surfaces. After a presentation of the major groups of antimicrobial plant phenolics, of their antimicrobial activity spectrum, and of the diversity of their mechanisms of action, their most promising sources will be reviewed. Since antimicrobial activity reduction often observed when comparing in vitro and in situ activities of plant phenolics has often been reported as a limit for their application, the effects of the composition and the microstructure of the matrices in which unwanted microorganisms are present (e.g., food and/or microbial biofilms) on their activity will be discussed. Then, the different strategies of delivery of antimicrobial phenolics to promote their activity in such matrices, such as their encapsulation or their association with edible coatings or food packaging materials are presented. The possibilities offered by encapsulation or association with polymers of packaging materials or coatings to increase the stability and ease of use of plant phenolics before their application, as well as to get systems for their controlled release are presented and discussed. Finally, the necessity to consider phenolic-rich antimicrobial plant extracts in combination with other factors consistently with hurdle technology principles will be discussed. For instance, several authors recently suggested that natural phenolic-rich extracts could not only extend the shelf-life of foods by controlling bacterial contamination, but could also coexist with probiotic lactic acid bacteria in food systems to provide enhanced health benefits to human.

Antimicrobial Activity of Polyphenols and Natural Polyphenolic Extracts on Clinical Isolates

Antibiotic resistance is a growing global problem that affects people, animals, the environment, and the economy. Many clinically relevant bacteria have become resistant to antibiotics, and this fact is emerging as one of the major threats to public health. The lack of new antibiotics, which is due to their time-consuming and costly development, exacerbates the problem. Therefore, it is necessary to identify new antimicrobial agents to treat bacterial and fungal infections. Plant extracts, which are valuable sources of bioactive compounds, mainly polyphenols, play an important role as a new strategy to combat pathogenic microorganisms. There is an extensive body of supporting evidence for the potent antibacterial and antifungal activities of polyphenols. Furthermore, some polyphenols show a synergistic effect when combined with antibiotics and antifungals, suggesting a promising alternative for therapeutic strategies against antibiotic resistance. However, only a few articles are found when searching the antibacterial or antifungal activities of polyphenols employing clinical isolates. Hence, this review focuses on the antimicrobial activity of polyphenols and extracts rich in polyphenols on clinical isolates, organized according to the World Health Organization priority pathogens classification.

Recent advances in industrial applications of seaweeds

Seaweeds have been generally utilized as food and alternative medicine in different countries. They are specifically used as a raw material for wine, cheese, soup, tea, noodles, etc. In addition, seaweeds are potentially good resources of protein, vitamins, minerals, carbohydrates, essential fatty acids and dietary fiber. The quality and quantity of biologically active compounds in seaweeds depend on season and harvesting period, seaweed geolocation as well as ecological factors. Seaweeds or their extracts have been studied as innovative sources for a variety of bioactive compounds such as polyunsaturated fatty acids, polyphenols, carrageenan, fucoidan, etc. These secondary metabolites have been shown to have antioxidant, antimicrobial, antiviral, anticancer, antidiabetic, anti-inflammatory, anti-aging, anti-obesity and anti-tumour properties. They have been used in pharmaceutical/medicine, and food industries since bioactive compounds from seaweeds are regarded as safe and natural. Therefore, this article provides up-to-date information on the applications of seaweed in different industries such as pharmaceutical, biomedical, cosmetics, dermatology and agriculture. Further studies on innovative extraction methods, safety issue and health-promoting properties should be reconsidered. Moreover, the details of the molecular mechanisms of seaweeds and their bioactive compounds for physiological activities are to be clearly elucidated.

Antibiofilm Efficacy of Luteolin Against Single and Dual Species of Candida albicans and Enterococcus faecalis

Candida albicans and Enterococcus faecalis biofilm-associated infections have been a huge challenge to the medical community. However, the efficacy of natural products against mixed biofilms of C. albicans and E. faecalis still remains largely unexploited. The aim of this study was to evaluate the efficacy of luteolin against planktonic cell growth, adhesion, and biofilm formation of C. albicans and E. faecalis in single and mixed cultures in vitro. The results showed that the minimum inhibitory concentrations of luteolin against planktonic cells of C. albicans, E. faecalis, and mixed cultures were 32 and 64 μg ml^–1, respectively. The results displayed that a remarkable variation in biofilm biomass, viability, structure, and composition of single and dual-species biofilms formed by mono- and dual-species biofilms of C. albicans and E. faecalis in the presence of luteolin was confirmed by mainly crystal violet staining assay (CVSA), optical microscope, field emission scanning electron microscope (FESEM), and confocal laser scanning microscope (CLSM). The tolerance of luteolin-treated single- and dual-species biofilms to antibiotics was found to obviously decrease, and the loss of biofilm matrix components (mainly polysaccharides and proteins) was revealed by CLSM. Moreover, luteolin was effective at inactivating biofilm cells, as well as destructing preformed biofilm structures by single and dual species by CVSA, FESEM, and CLSM. Collectively, these data indicate the potential of luteolin as a promising antibiofilm agent for the therapeutic management of biofilm-related infections induced by single and dual species of C. albicans and E. faecalis.

Polyphenolic Antibacterials for Food Preservation: Review, Challenges, and Current Applications

Natural alternatives replacing artificial additives have gained much attention in the consumer’s view because of the growing search for clean label products that are devoid of carcinogenic and toxic effects. Plant polyphenols are considered as suitable alternative natural preservatives with antioxidant and antimicrobial properties. However, their uses in the food industry are undermined by a series of limitations such as low solubility and stability during food processing and storage, lack of standardization, and undesirable organoleptic properties. Different approaches in the use of polyphenols have been proposed in order to overcome the current hurdles related to food preservation. This review article specifically focuses on the antibacterial activity of plant-derived polyphenols as well as their applications as food preservatives, main challenges, and other trends in the food industry.

Synergistic potential of nutraceuticals: mechanisms and prospects for futuristic medicine

Nutraceuticals are valued for their therapeutic effects and numerous health benefits. In recent years, several studies have demonstrated their superior performances when co-delivered; the concept of synergism has been established for various bioactives. Apart from improvements in the bioavailability of partnering compounds, this approach can protect the radical scavenging potential and biological effects of individual compounds. In this review, the intricate mechanisms that promote synergistic effects when bioactive compounds are co-delivered are detailed. Importantly, a range of potential medical applications that have been established through such synergistic effects is presented, emphasizing recent developments in this field. Also, a section has been devoted to highlighting perspectives on co-encapsulation at the nanoscale for improved synergistic benefits. While prospects for the treatment of chronic diseases are well-demonstrated, several challenges and safety concerns remain, and these have been discussed, providing recommendations for future research.

A combined approach based on matrix solid-phase dispersion extraction assisted by titanium dioxide nanoparticles and liquid chromatography to determine polyphenols from grape residues

A simple and efficient low-cost matrix solid phase dispersion (MSPD) extraction assisted by TiO₂ nanoparticles and diatomaceous earth has been developed for the extraction of phenolic compounds from grape and grape pomace wastes. Experimental conditions for MSPD extraction were optimized by a factorial design and a surface response methodology. The simultaneous identification and quantification of eight main natural polyphenols (caffeic, p-coumaric, dihydroxybenzoic and gallic acid, rutin, resveratrol, quercetin and catechin) was possible by combining MSPD and capillary liquid chromatography coupled to a diode array detection and a mass simple quadrupole analyzer (cLC-DAD-MS). Good linearity and acceptable LOD (0.05-62 µg·g^-1) and LOQ (0.2-207 µg·g^-1) were obtained. The quantities of extracted polyphenols were within 2.4 and 333 µg·g^-1, with catechin and rutin the most abundant compounds in grape pomace and grape wastes, respectively. Furthermore, considering the prospective uses of the winery bioresidues, the extracts have been characterised in terms of bioactive properties (several antioxidant activities and bacterial inhibition against Staphylococcus aureus, Escherichia coli and Pseudomona aeruginosa) and parameters such as total polyphenol and total flavonoid content. The high antioxidant activity (IC₅₀ 5.0 ± 0.4 µg ·g^-1 against DPPH radical) and antibacterial activity (2.2 ± 0.3 mg·mL^-1) suggests that the methodology developed is efficient, rapid and promising for the extraction of phenolic compounds with potential application as bioactive ingredients in food and cosmetic industries.

Sustainable sources for antioxidant and antimicrobial compounds used in meat and seafood products

The contribution of food in promotion of health has become of most importance. The challenges that lie before the global food supply chain, such as climate changes, food contamination, and antimicrobial resistance may compromise food safety at international scale. Compounds with strong antimicrobial and antioxidant activity can be extracted from different natural and sustainable sources and may contribute to extend the shelf life of meat and seafood products, enhance food safety and enrich foods with additional biologically active and functional ingredients. This chapter describes the use of bioprotective cultures, essential oils, plant extracts, seaweed extracts and grape pomace compounds in production of value-added meat and seafood products with improved shelf life and safety, following the requests from the market and consumers.

Natural Antimicrobials Suitable for Combating Desiccation-Resistant Salmonella enterica in Milk Powder

Some Salmonella enterica strains survive well in low-water activity (low-a_w) foods and cause frequent salmonellosis outbreaks in these products. Methods are needed to overcome such desiccation-resistant Salmonella and to improve the safety of low-a_w foods. Building on a recent finding, we hypothesized that natural antimicrobial food additives, which are active against cytoplasmic membrane, could overcome this desiccation resistance phenomenon, and thus, sensitize the pathogen to drying and mild processing. Food additives were screened for the ability to cause leakage of intracellular potassium ions; retention of these ions is vital for protecting Salmonella against desiccation. Two antimicrobial food additives, carvacrol and thymol, caused considerable potassium leakage from the desiccation-resistant S. enterica serovars, Tennessee and Livingstone. Thus, carvacrol and thymol were investigated for their ability to sensitize the desiccation-adapted S. enterica to heat treatment. The combined use of food additives, at their minimum inhibitory concentrations, with heat treatment at 55 °C for 15 min caused 3.1 ± 0.21 to more than 5.5 log colony forming unit (CFU)/mL reduction in desiccation-adapted S. enterica, compared to 2.4 ± 0.53–3.2 ± 0.11 log CFU/mL reduction by sole heat treatment. Carvacrol was the additive that caused the greatest potassium leakage and sensitization of Salmonella to heat; hence, the application of this compound was investigated in a food model against Salmonella Typhimurium ASD200. Addition of carvacrol at 200 or 500 ppm into liquid milk followed by spray-drying reduced the strain’s population by 0.9 ± 0.02 and 1.3 ± 0.1 log CFU/g, respectively, compared to 0.6 ± 0.02 log CFU/g reduction for non-treated spray-dried milk. Additionally, freeze-drying of milk treated with high levels of carvacrol (5000 ppm) reduced the population of Salmonella Typhimurium ASD200 by more than 4.5 log CFU/g, compared to 1.1 ± 0.4 log CFU/g reduction for the freeze-dried untreated milk. These findings suggest that carvacrol can combat desiccation-resistant S. enterica, and thus, potentially improve the safety of low-a_w foods.

Chemical Composition, Antioxidant and Antimicrobial Activity of Raspberry, Blackberry and Raspberry-Blackberry Hybrid Leaf Buds

In our investigation, the chemical composition and bioactive potential of leaf buds of raspberry, blackberry, and a raspberry-blackberry hybrid were determined. Antioxidant and antimicrobial properties were tested in water (W), ethanol-water (EW), and glycerol-water (GW) extracts from the buds. These plant organs contain relatively large amounts of minerals, especially Fe. The total antioxidant capacity (TAC) measured by the ABTS and DPPH methods ranged from 2.86 to 12.19 and 6.75 to 24.26 mmol per 100 g fresh weight (FW) of buds, respectively. TAC values were generally higher in the raspberry than in the case of blackberry and raspberry-blackberry hybrid extracts. The antioxidant properties of the extracts were strongly positively correlated with their content of total phenolic (TP). No such relationship was noted for ascorbic acid (AA), whose concentration in all extracts was at a similarly low level. Antioxidant properties determined in vitro were confirmed for the GW extract from raspberry leaf buds in biological test based on the growth parameters of Δsod1 Saccharomyces cerevisiae mutant cells in hypertonic medium. The extracts also exhibited strong antibacterial properties against Staphylococcus aureus and Enterococcus faecalis and weaker against Enterobacter aerogenes. The studied leaf buds could be therefore an unconventional source of minerals, natural antioxidants and antibacterial compounds with potential applications in the food, pharmaceutical, and cosmetics industries.

Mechanisms of Action of Luteolin Against Single- and Dual-Species of Escherichia coli and Enterobacter cloacae and Its Antibiofilm Activities

Escherichia coli and Enterobacter cloacae are major foodborne pathogens and can form challenging single/mixed biofilms. A recent study demonstrated that luteolin (LUT) exhibits antibacterial activities against some pathogens; however, the mechanisms underlying the effects of LUT on planktonic and biofilm bacteria have never been fully elucidated. This study aimed to determine the antibacterial activity and its mechanism of action against E. coli and E. cloacae. Here, the antimicrobial mode of LUT was explored by evaluating alterations in both cell membrane integrity and cell morphology, and the antibiofilm activity of LUT was investigated using quantitative and qualitative assays. The results showed that minimal inhibitory concentration and minimum bactericidal concentration values of LUT against E. coli were 64 and 128 μg/mL and 128 and 256 μg/mL for E. cloacae mono- and dual-species, respectively. LUT impaired cell membrane integrity, as demonstrated by the remarkable increase in the number of membrane-damaged cells and definite variations in cell morphology. Moreover, LUT presented robust inhibitory effects on biofilm formation and the capacity to kill mono- and dual-species biofilm cells. Overall, these data show the potential benefit of using a natural antimicrobial and/or preservative in the food industry, LUT, to control mono- and mixed-species or biofilm-associated infections.

Antimicrobial Activity of Selected Red and White Wines against Escherichia coli: In Vitro Inhibition Using Fish as Food Matrix

Five different wines (standard Graševina, macerated Graševina with and without sulfur, rosé, and standard Plavac Mali), all typical Croatian wines, were tested to determine the antimicrobial activity against two Escherichia coli bacterial strains (ATCC^® 25922 and ATCC^® 8739) in vitro and using sea bass (Dicentrarchus labrax) fillets as food matrix. The chemical composition of wines (pH, acidity, alcohol, total phenolics, anthocyanins, tannins, and sulfur content) and antimicrobial activity (minimal inhibitory concentration (MIC), agar-well diffusion method) were determined. The total phenolic content of the wines ranged from 305-3210 mg gallic acid equivalents per liter (GAE/L), and did not correlate to antimicrobial activity. The two wines with the lowest phenolic content (standard Graševina and rosé) had the lowest MIC values (122 and 429 mg GAE/L). A specific relation between the winemaking process and a particular MIC value was not established. There was also no relation found between the pH value, ethanol content, sulfur, or phenolics in regards to the antimicrobial effect. In fish fillets marinated in wine + water mixture (v/v = 1:1) and inoculated with 7 log colony forming units (CFU)/25 g the growth of bacteria was reduced after three days of storage at 4 °C. Subsequent storage resulted in the growth of bacteria in all samples, with the lowest growth of E. coli ATCC^® 25922 in macerated Graševina and E. coli ATCC^® 8739 in standard Graševina. All wines showed the capacity to reduce the number and growth of heavily infected sea bass filets, but correlation with specific wine constituents was not found. Taking into account the numerous reactive mechanisms between food and wine, all in vitro studies in controlled laboratory conditions should be further verified in the relevant environment, and additional research is needed to clarify the role of individual wine components in the mechanism of antimicrobial activity.

Antibacterial Activity of Four Plant Extracts Extracted from Traditional Chinese Medicinal Plants against Listeria monocytogenes, Escherichia coli, and Salmonella enterica subsp. enterica serovar Enteritidis

The worldwide ethnobotanical use of four investigated plants indicates antibacterial properties. The aim of this study was to screen and determine significant antibacterial activity of four plant extracts in vitro and in a poultry digest model. Using broth microdilution, the concentrations at which four plant extracts inhibited Listeria monocytogenes, Salmonella enteritidis, and Escherichia coli over 24 h was determined. Agrimonia pilosa Ledeb, Iris domestica (L.) Goldblatt and Mabb, Anemone chinensis Bunge, and Smilax glabra Roxb all exhibited a minimum inhibitory concentration (MIC) of 62.5 mg/L and a minimum bactericidal concentration (MBC) of 500 mg/L against one pathogen. A. pilosa Ledeb was the most effective against L. monocytogenes and E. coli with the exception of S. enteritidis, for which A. chinensis Bunge was the most effective. Time–kills of A. pilosa Ledeb and A. chinensis Bunge against L. monocytogenes, E. coli and S. enteritidis incubated in poultry cecum were used to determine bactericidal activity of these plant extracts. A. chinensis Bunge, significantly reduced S. enteritidis by ≥ 99.99% within 6 h. A. pilosa Ledeb exhibited effective significant bactericidal activity within 4 h against L. monocytogenes and E. coli. This paper highlights the potential of these plant extracts to control pathogens commonly found in the poultry gastrointestinal tract.

Antimicrobial polyphenol-rich extracts: Applications and limitations in the food industry

One of the common ways to prevent food spoilage throughout product's shelf life is by using artificial/synthetic preservatives. However, the growing negative perception of consumers over synthetic preservatives has encouraged the food industry to consider their natural alternatives. Plant extracts, increasingly recognized as consumer-friendly, represent a valuable source of active compounds, mostly polyphenols, with potent antimicrobial and antibiofilm activities. Hence, this article focuses mainly on the antimicrobial activity of plant-based polyphenol-rich extracts as well as on their potential use and limitations in the food industry. Some new trends such as antimicrobial food packaging combined with plant extracts and photodynamic inactivation (PDI) combined with a natural photosensitiser, curcumin, are discussed as well.

Antimicrobial mechanism of luteolin against Staphylococcus aureus and Listeria monocytogenes and its antibiofilm properties

Luteolin (LUT) is a naturally occurring compound found in a various of plants. Few recent studies have reported LUT antimicrobial activities against bacterial pathogens, however, the fundamental LUT mediated antimicrobial mechanism has never been elucidated. This study aimed to investigate the antimicrobial activities of LUT and its mode of action against Staphylococcus aureus and Listeria monocytogenes, either as planktonic cells or as biofilms. Here, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of LUT against S. aureus and L. monocytogenes were determined using the broth microdilution method, and the antimicrobial mode of LUT was elucidated by evaluating the variations in both cell membrane integrity and cell morphology. Moreover, the biofilm inhibition was measured by crystal violet staining assay, while its qualitative imaging was achieved by confocal laser scanning microscope and field emission scanning electron microscope. MIC and MBC values of LUT against S. aureus were 16-32 and 32-64 μg/mL, and 32-64 and 64-128 μg/mL for L. monocytogenes. LUT destroyed the cell membrane integrity, as evidenced by a significant increase in the number of non-viable cells, and well-defined variations in cell morphology. Moreover, LUT presented robust inhibitory effects on the biofilm formation, enhanced antibiotics diffusion within biofilms and killed efficiently mono- and dual-species biofilm cells. Overall, LUT demonstrates potent antimicrobial properties on planktonic and biofilm cells, and the biofilm formation, and thus has the potential use as a natural food preservative in foods.

Antioxidant and Antimicrobial Potential of Phenolic Metabolites from Traditionally Used Mediterranean Herbs and Spices

The phenolic extracts of fifteen Mediterranean medicinal plants, as well as their antioxidant and antimicrobial activities were investigated to grade their potential as additives in the food industry. Phenolic profiles of plant extracts were determined spectrophotometrically (total phenolics and phenolic subgroups) while individual compounds were identified using chromatographic assays. The biological activity of samples was determined using five antioxidant assays, while the antibacterial potential was determined against six foodborne pathogens (Camplyobacter coli, Escherichia coli, Salmonela Infantis, Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus). The results showed significant variations in phenolic profile of plants and consequently their biological activity. Bearberry contained the highest concentration of phenolics, was extremely rich in non-flavonoids and also had the highest amount of catechins that resulted with good reducing and free radical scavenging properties and low chelating activity. All extracts were not effective against tested microorganisms with Gram-positive bacteria being more sensitive (especially S. aureus). The most effective extracts were St. Johns wort against S. aureus with minimal inhibitory concentration (MIC) of 1.00 mg/mL), bay laurel and nettle against B. cereus (MICs of 1.67 mg/mL), and woodland strawberry against L. monocytogenes (MIC of 3.33 mg/mL).