Resveratrol, pterostilbene, and baicalein: plant-derived anti-biofilm agents

Vitis vinifera L. Leaf Extract, a Microbiota Green Ally against Infectious and Inflammatory Skin and Scalp Diseases: An In-Depth Update

The skin microbiota, with its millions of bacteria, fungi, and viruses, plays a key role in balancing the health of the skin and scalp. Its continuous exposure to potentially harmful stressors can lead to abnormalities such as local dysbiosis, altered barrier function, pathobiont overabundance, and infections often sustained by multidrug-resistant bacteria. These factors contribute to skin impairment, deregulation of immune response, and chronic inflammation, with local and systemic consequences. In this scenario, according to the needs of the bio-circular-green economy model, novel harmless strategies, both for regulating the diverse epidermal infectious and inflammatory processes and for preserving or restoring the host skin eubiosis and barrier selectivity, are requested. Vitis vinifera L. leaves and their derived extracts are rich in plant secondary metabolites, such as polyphenols, with antioxidant, anti-inflammatory, antimicrobial, and immunomodulatory properties that can be further exploited through microbe-driven fermentation processes. On this premise, this literature review aims to provide an informative summary of the most updated evidence on their interactions with skin commensals and pathogens and on their ability to manage inflammatory conditions and restore microbial biodiversity. The emerging research showcases the potential novel beneficial ingredients for addressing various skincare concerns and advancing the cosmeceutics field as well.

Baicalein glycymicelle ophthalmic solution: Preparation, in vitro antimicrobial activities, and antimicrobial mechanism evaluations

The purpose of this study was to develop a novel baicalein (BAI) loaded glycymicelle ophthalmic solution with small molecule phytochemical glycyrrhizin as nanocarriers and to explore this solution's potential as an antimicrobial agent against ocular infections. The optimized BAI glycymicelles had a high encapsulation efficiency (98.76 ± 1.25 %), a small particle size (54.38 ± 2.41 nm), a uniform size distribution (polydispersity index = 0.293 ± 0.083), and a zeta potential of -28.3 ± 1.17 mV. The BAI glycymicelle ophthalmic solution exhibited an excellent short-term storage stability. BAI glycymicelles significantly increased the apparent solubility and in vitro release capability of BAI. The BAI glycymicelle ophthalmic solution exhibited no hen's egg-chorioallantoic membrane' irritation and strong in vivo ocular tolerance in rabbits. The BAI glycymicelles noticeably enhanced the in vivo corneal permeation. The BAI glycymicelles also precipitated increased in vitro antioxidant activity and significantly improved in vitro antipathogen activities. Various antimicrobial mechanisms, including the destruction of the bacterial cell wall, damage to the bacterial cell membranes, interruptions to the biofilm structure, and the apoptosis of bacteria, were inflicted on BAI glycymicelles. These findings provided useful knowledge regarding the development of a novel ophthalmic solution and formulation of BAI.

Revealing active constituents within traditional Chinese Medicine used for treating bacterial pneumonia, with emphasis on the mechanism of baicalein against multi-drug resistant Klebsiella pneumoniae

ETHNOPHARMACOLOGICAL RELEVANCE

The emergence of antibiotic-resistant bacteria has rendered it more challenging to treat bacterial pneumonia. Traditional Chinese medicine (TCM) has superior efficacy in the treatment of pneumonia, and it has the unique advantage of antibacterial resistance against multi-drug resistant (MDR) bacteria, but the medication rule and pharmacological mechanism of its antibacterial activity are not clear.

AIM OF THE STUDY

This study aims to reveal Chinese medication patterns in treating bacterial pneumonia to select bioactive constituents in core herbs, predict their pharmacological mechanisms and further explore their antibacterial ability against clinically isolated MDR Klebsiella pneumoniae (KP) and their antibacterial mechanisms.

MATERIALS AND METHODS

The high-frequency medicinal herbs to treat lung diseases were first screened from Pharmacopoeia of the People's Republic of China (ChP.), and then bioactive compounds in core herbs and targets for compounds and disease were collected. Potential targets, signaling pathways, and drugs' core components were determined by constructing protein-protein interaction network, enrichment analysis and "component-target-pathway-disease" network were mapped by Cytoscape 3.8.2, and the potential therapeutic value of selected core components was verified by comparing the disease targets in the GEO database with the herbal component targets in the ITCM database. The clinically isolated KP were screened by drug sensitivity tests with meropenem (MEM), polymyxin E (PE), and tigecycline and biofilm-forming assay; broth microdilution, chessboard methods and biofilm morphology and permeability experiments were employed to determine the antibacterial, bactericidal and biofilm inhibition ability of selected bioactive constituents alone and in combination with antibiotics; The mechanism of bioactive components on quorum sensing (QS) genes LuxS and LuxR was predicted by molecular docking and tested by RT-PCR.

RESULTS

The 13 core Chinese medicines were obtained by mining ChP., and 615 potential targets of core herbal medicine were screened, and the PI3K-Akt signaling pathway might play crucial roles in the therapeutic process. In-vitro experiments revealed that the selected core compounds, including forsythoside B, baicalin, baicalein, and forsythin, all have antibacterial activity, in which baicalein had the strongest ability and a synergistic effect in combination with MEM or PE. Their synergy exhibited a stronger effect on biofilms of MDR KP, inhibiting biofilm formation, disrupting formed biofilms, and removing the residual structures of dead bacteria. Baicalein was predicted to have stable binding capacity to LuxS and LuxR genes by molecular docking, and RT-PCR results verified that the combination of baicalein with MEM or PE was effective in inhibiting the expression of QS genes (LuxS and LuxR) and consequently suppressing biofilm formation.

CONCLUSION

The core Chinese herbal medicine in the ChP. to treat lung diseases has a multi-component, multi-target, and multi-pathway synergy to improve bacterial pneumonia. Experimental studies have confirmed that the bioactive compound baicalein was able to combat MDR KP alone and synergistic with MEM or PE, inhibited and disrupted biofilms via regulating LuxS and LuxR genes, and further disturbed quorum sensing system to promote the therapeutic efficacy, which provides a new pathway and rationale for treating MDR KP-induced bacterial pneumonia.

The dynamics of touch-responsive gene expression in cereals

Wind, rain, herbivores, obstacles, neighbouring plants, etc. provide important mechanical cues to steer plant growth and survival. Mechanostimulation to stimulate yield and stress resistance of crops is of significant research interest, yet a molecular understanding of transcriptional responses to touch is largely absent in cereals. To address this, we performed whole-genome transcriptomics following mechanostimulation of wheat, barley, and the recent genome-sequenced oat. The largest transcriptome changes occurred ±25 min after touching, with most of the genes being upregulated. While most genes returned to basal expression level by 1-2 h in oat, many genes retained high expression even 4 h post-treatment in barley and wheat. Functional categories such as transcription factors, kinases, phytohormones, and Ca2+ regulation were affected. In addition, cell wall-related genes involved in (hemi)cellulose, lignin, suberin, and callose biosynthesis were touch-responsive, providing molecular insight into mechanically induced changes in cell wall composition. Furthermore, several cereal-specific transcriptomic footprints were identified that were not observed in Arabidopsis. In oat and barley, we found evidence for systemic spreading of touch-induced signalling. Finally, we provide evidence that both the jasmonic acid-dependent and the jasmonic acid-independent pathways underlie touch-signalling in cereals, providing a detailed framework and marker genes for further study of (a)biotic stress responses in cereals.

The potential role of plant secondary metabolites on antifungal and immunomodulatory effect

With the widespread use of antibiotic drugs worldwide and the global increase in the number of immunodeficient patients, fungal infections have become a serious threat to global public health security. Moreover, the evolution of fungal resistance to existing antifungal drugs is on the rise. To address these issues, the development of new antifungal drugs or fungal inhibitors needs to be targeted urgently. Plant secondary metabolites are characterized by a wide variety of chemical structures, low price, high availability, high antimicrobial activity, and few side effects. Therefore, plant secondary metabolites may be important resources for the identification and development of novel antifungal drugs. However, there are few studies to summarize those contents. In this review, the antifungal modes of action of plant secondary metabolites toward different types of fungi and fungal infections are covered, as well as highlighting immunomodulatory effects on the human body. This review of the literature should lay the foundation for research into new antifungal drugs and the discovery of new targets. KEY POINTS: • Immunocompromised patients who are infected the drug-resistant fungi are increasing. • Plant secondary metabolites toward various fungal targets are covered. • Plant secondary metabolites with immunomodulatory effect are verified in vivo.

Multicomponent Antibiofilm Lipid Nanoparticles as Novel Platform to Ameliorate Resveratrol Properties: Preliminary Outcomes on Fibroblast Proliferation and Migration

The well-being of skin and mucous membranes is fundamental for the homeostasis of the body and thus it is imperative to treat any lesion quickly and correctly. In this view, polyphenols might assist and enhance a successful wound healing process by reducing the inflammatory cascade and the production of free radicals. However, they suffer from disadvantageous physico-chemical properties, leading to restricted clinical use. In this work, a complex mixture of PEGylated lipid, Glyceryl monoester, 18-β-Glycyrrhetinic Acid and Menthol was designed to entrap Resveratrol (RSV) as the active ingredient and further produce lipid nanoparticles (LNPs) by homogenization followed by high-frequency sonication. The nanosystem was properly characterized in terms of particle size (DLS, SEM), zeta potential, drug loading, antioxidant power (DPPH), release behaviour, cytocompatibility, wound healing and antibiofilm properties. The optimized lipid mixture was homogeneous, melted at 57-61 °C and encapsulated amorphous RSV (4.56 ± 0.04% w/w). The RSV-loaded LNPs were almost monodispersed (PDI: 0.267 ± 0.010), with nanometric size (162.86 ± 3.12 nm), scavenger properties and suitable DR% and LE% values (96.82 ± 1.34% and 95.17 ± 0.25%, respectively). The release studies were performed to simulate the wound conditions: 1-octanol to mimic the lipophilic domains of biological tissues (where the First Order kinetic was observed) and citrate buffer pH 5.5 according to the inflammatory wound exudate (where the Korsmeyer-Peppas kinetic was followed). The biological and microbiological evaluations highlighted fibroblast proliferation and migration effects as well as antibiofilm properties at extremely low doses (LNPs: 22 μg/mL, corresponding to RSV 5 µM). Thus, the proposed multicomponent LNPs could represent a valuable RSV delivery platform for wound healing purposes.

In vitro antifungal activity of Shikonin against Candida albicans by inducing cellular apoptosis and necrosis

BACKGROUND

Our previous studies showed that Shikonin (SK) had a strong anti-Candida albican (C. albicans) activity, especially against some fluconazole-resistant strains, which is probably due to the oxidative damage of SK to C. albicans.

METHODS AND RESULTS

In this study, we expanded the antifungal spectrum and evaluate the toxicity of SK. The results indicated that SK also exhibited potent invitro antifungal activities against other pathogenic fungi such as other Candida, Aspergillus, Cryptococcus, and Dermatophytes, but did not display apparent toxicity to the mammalian cells, suggesting that SK is safe to be a potential antifungal drug. Furtherly, we analyze the exact mechanism of SK against C. albicans. We found that SK could induce a series of apoptosis characteristics, including phosphatidylserine externalization, chromatin condensation and fragmentation, decreased cytochrome c oxidase activity as well as caspase activation.

CONCLUSIONS

In summary, this study highlighted the antifungal activity and mechanism of SK against C. albicans, providing a potential therapeutic strategy for C. albicans infection.

Targeting Virulence Factors of Candida albicans with Natural Products

Natural products derived from natural resources, including nutritional functional food, play an important role in human health. In recent years, the study of anti-fungal and other properties of agri-foods and derived functional compounds has been a hot research topic. Candida albicans is a parasitic fungus that thrives on human mucosal surfaces, which are colonized through opportunistic infection. It is the most prevalent cause of invasive fungal infection in immunocompromised individuals, resulting in a wide variety of clinical symptoms. Moreover, the efficacy of classical therapeutic medications such as fluconazole is often limited by the development of resistance. There is an ongoing need for the development of novel and effective antifungal therapy and medications. Infection of C. albicans is influenced by a great quantity of virulence factors, like adhesion, invasion-promoting enzymes, mycelial growth, and phenotypic change, and among others. Furthermore, various natural products especially from food sources that target C. albicans virulence factors have been researched, providing promising prospects for C. albicans prevention and treatment. In this review, we discuss the virulence factors of C. albicans and how functional foods and derived functional compounds affect them. Our hope is that this review will stimulate additional thoughts and suggestions regarding nutritional functional food and therapeutic development for patients afflicted with C. albicans.

The Application of Small Molecules to the Control of Typical Species Associated With Oral Infectious Diseases

Oral microbial dysbiosis is the major causative factor for common oral infectious diseases including dental caries and periodontal diseases. Interventions that can lessen the microbial virulence and reconstitute microbial ecology have drawn increasing attention in the development of novel therapeutics for oral diseases. Antimicrobial small molecules are a series of natural or synthetic bioactive compounds that have shown inhibitory effect on oral microbiota associated with oral infectious diseases. Novel small molecules, which can either selectively inhibit keystone microbes that drive dysbiosis of oral microbiota or inhibit the key virulence of the microbial community without necessarily killing the microbes, are promising for the ecological management of oral diseases. Here we discussed the research progress in the development of antimicrobial small molecules and delivery systems, with a particular focus on their antimicrobial activity against typical species associated with oral infectious diseases and the underlying mechanisms.

Pterostilbene Coupled with Physical Exercise Effectively Mitigates Collagen-Induced Articular Synovial by Correcting the PI3K/Akt/NF-κB Signal Pathway

Studies have revealed that a novel anti-inflammatory mediator─maresin-1 (MaR1)─can reduce the level of inflammatory factors. There is evidence that physical exercise (PE) promotes the biosynthesis of MaR1, leading to the prevention of rheumatoid arthritis (RA). Previously, we have proven that resveratrol can mitigate the formation of RA. Pterostilbene (Pte) is an analogue of resveratrol, but it is around four times more bioavailable. Hence, we hypothesize that Pte could be more effective in preventing RA, in particular, when accompanied by moderate PE. Based on this hypothesis, we explored the preventive effect of Pte combined with PE on a bovine type II collagen (BIIC)-stimulated rat RA model and its underlying molecular mechanism. Compared with the BIIC-stimulated group, the serum content of MaR1 with continuous intervention of Pte plus PE for 8 weeks was significantly increased to 46.3 pg/mL from 7.2 pg/mL in BIIC-treated alone. Besides, the variation in the relative expression levels of p-NF-κB and p-Akt was reversed with the administration of Pte plus PE. More importantly, the in vitro results confirmed that the treatment of Pte plus MaR1 inhibited proliferation and apoptosis and promoted the autophagy of the interleukin (IL)-1β-stimulated primary rat synovial cells through the PI3K/Akt/NF-κB signal pathway. Collectively, the oral administration of Pte plus moderate PE helped to ameliorate the pathological process of RA by correcting the PI3K/Akt/NF-κB signal pathway.

Assessment of the Antibacterial Mechanism of Pterostilbene against Bacillus cereus through Apoptosis-like Cell Death and Evaluation of Its Beneficial Effects on the Gut Microbiota

Foods contaminated by harmful substances such as bacteria and viruses have caused more than 200 kinds of diseases, ranging from diarrhea to cancer. Among them, Bacillus cereus (B. cereus) is a foodborne pathogen that commonly contaminates raw meat, fresh vegetables, rice, and uncooked food. The current chemical preservatives may have adverse effects on food and even human health. Therefore, natural antibacterial agents are sought after as alternative preservatives. Stilbene compounds, including pterostilbene (PT), pinostilbene (PS), and piceatannol (PIC), which have many health benefits and exhibit antibacterial activity, were tested against B. cereus. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of PT, PS, and PIC against B. cereus ranged from 25 to 100 μg/mL. From the time-kill curve assay, PT reduced B. cereus cell survival, increased intracellular reactive oxygen species (ROS), and induced apoptosis-like cell death (ALD) in a dose-dependent manner. The quantitative real-time polymerase chain reaction (qPCR) results confirmed that treatment with PT induced genetic changes related to ALD, such as an increase in RecA gene expression and a decrease in LexA gene expression. In addition, PT showed a beneficial effect on the gut microbiota that increased the abundance of Bacteroidetes and lowered the abundance of Firmicutes. Taken together, our results showed that PT has antibacterial effects against B. cereus via ALD and is beneficial for promoting healthy gut microbiota that is worthy for the development of antibacterial agents for the food industry.

Low-molecular weight chitosan enhances antibacterial effect of antibiotics and permeabilizes cytoplasmic membrane of Staphylococcus epidermidis biofilm cells

This study evaluated the effect of low-molecular weight chitosan on Staphylococcus epidermidis, a common colonizer of joint implants and other prosthetic devices. We have also attempted to elucidate its mechanism of action. Chitosan was found to be effective against both the planktonic and biofilm cells (MIC₈₀ 35-40 mg/L; MBIC₈₀ 40-150 mg/L), in contrast to the antibiotics erythromycin and tetracycline with no antibiofilm activity (MBIC₈₀ not found). In combination, chitosan had an additive effect with antibiotics on suspension growth of S. epidermidis (FICi 0.7-1.0), and the combinatory action caused a complete inhibition of biofilm metabolic activity in some cases. In addition, chitosan caused rapid cellular damage and enhanced antihaemolytic activity of tetracycline in combination towards S. epidermidis biofilm cells. Chitosan efficiently inhibited S. epidermidis growth acting via cell membrane damage, yet the extent of antimicrobial and antibiofilm activities was quite strain-specific. It was proved to be a very efficient antimicrobial agent worth further examination as a potent candidate in pharmaceutical research. Apart from antimicrobial activity, it also acted as antivirulence enhancing agent which is a very promising strategy for alternative infectious diseases treatment.

In vitro antibiofilm activity of resveratrol against avian pathogenic Escherichia coli

BACKGROUND

Avian pathogenic Escherichia coli (APEC) strains cause infectious diseases in poultry. Resveratrol is extracted from Polygonum cuspidatum, Cassia tora Linn and Vitis vinifera, and displays good antimicrobial activity. The present study aimed to investigate the antibiofilm effect of resveratrol on APEC in vitro. The minimum inhibitory concentration (MIC) of resveratrol and the antibiotic florfenicol toward APEC were detected using the broth microdilution method. Then, the effect of resveratrol on swimming and swarming motility was investigated using a semisolid medium culture method. Subsequently, the minimum biofilm inhibitory concentration (MBIC) and the biofilm eradication rate were evaluated using crystal violet staining. Finally, the antibiofilm activity of resveratrol was observed using scanning electron microscopy (SEM). Meanwhile, the effects of florfenicol combined with resveratrol against biofilm formation by APEC were evaluated using optical microscopy (OM) and a confocal laser scanning microscopy (CLSM).

RESULTS

The MICs of resveratrol and florfenicol toward APEC were 128 μg/mL and 64 μg/mL, respectively. The swimming and swarming motility abilities of APEC were inhibited in a resveratrol dose-dependent manner. Furthermore, resveratrol showed a significant inhibitory activity against APEC biofilm formation at concentrations above 1 μg/mL (p < 0.01). Meanwhile, the inhibitory effect of resveratrol at 32 μg/mL on biofilm formation was observed using SEM. The APEC biofilm was eradicated at 32 μg/mL of resveratrol combined with 64 μg/mL of florfenicol, which was observed using CLSM and OM. Florfenicol had a slight eradication effect of biofilm formation, whereas resveratrol had a strong biofilm eradication effect toward APEC.

CONCLUSION

Resveratrol displayed good antibiofilm activity against APEC in vitro, including inhibition of swimming and swarming motility, biofilm formation, and could eradicate the biofilm.

Ciprofloxacin-Resistant Staphylococcus aureus Displays Enhanced Resistance and Virulence in Iron-Restricted Conditions

The unreasonable misuse of antibiotics has led to the emergence of large-scale drug-resistant bacteria, seriously threatening human health. Compared with drug-sensitive bacteria, resistant bacteria are difficult to clear by host immunity. To fully explore the adaptive mechanism of resistant bacteria to the iron-restricted environment, we performed data-independent acquisition-based quantitative proteomics on ciprofloxacin (CIP)-resistant (CIP-R) Staphylococcus aureus in the presence or absence of iron. On bioinformatics analysis, CIP-R bacteria showed stronger amino acid synthesis and energy storage ability. Notably, CIP-R bacteria increased virulence by upregulating the expression of many virulence-related proteins and enhancing the synthesis of virulence-related amino acids under iron-restricted stress. This study will help us to further explain the adaptive mechanisms that lead to bacterial resistance to antibiotics depending on the host environment and provide insights into the development of novel drugs for the treatment of drug-resistant bacterial infections.

Clinical research on traditional Chinese medicine treatment for bacterial vaginosis

Bacterial vaginosis (BV) is a common disease among women of reproductive age, with a serious impact on their daily life and health. At present, the most common treatment for BV is to take antibiotics, which results in good short-term treatment effects, but poor long-term effects. Traditional Chinese medicine (TCM) has been used to treat BV for over a millennium, with little risk of triggering drug resistance and adverse effects. Based on syndrome differentiation, there are three oral TCM treatment strategies for BV, including invigorating spleen, clearing dampness and heat, and nourishing kidney. The oral TCM prescriptions, such as Yi Huang decoction, Longdan Xiegan decoction, Zhibai Dihaung decoction, and so on are commonly used. Topical TCM treatment is also popular in China. According to the research results of pharmacological effects of active TCM ingredients, the most potential mechanisms of TCM for BV treatment are immune-enhancement effects, antibacterial activity, and estrogen-liked effects. Nonetheless, the multi-constituent of herbs may result in possible disadvantages to BV treatment, and the pharmacological mechanisms of TCM need further study. Here, we provide an overview of TCM compounds and their preparations used for BV, based on the pathogenesis and the potential therapeutic mechanisms, therefore providing a reference for further studies.

Intestinal pharmacokinetics of resveratrol and regulatory effects of resveratrol metabolites on gut barrier and gut microbiota

Resveratrol, a dietary polyphenol, has a variety of intestinal bioactivities. However, its material basis remains unknown. This study examined the intestinal pharmacokinetics of resveratrol using HPLC-MS/MS. After oral ingestion in mice, resveratrol and its sulfation metabolites were identified in copious amount in the entire intestinal tract and feces. The glucuronidation metabolites were found in major quantity only in the small intestine. The amount of resveratrol and its metabolites in the total intestine peaked at 4 h, with a concentration of 200 ± 74.8 μM, which corresponded to 14.0% of the administrated dose. During in vitro fermentation, resveratrol-3-O-sulfate, but not resveratrol, significantly promoted the growth of Lactobacillus reuteri (10-fold higher). During the incubation with Caco-2 cells, resveratrol-3-O-sulfate significantly up-regulated the mRNA expressions of tight junction and mucin-related proteins. In conclusion, the intestinal concentration of resveratrol could partially support its intestinal bioactivities, which may be mediated through the actions of its metabolites.

Anti-biofilm activity of a semi-synthetic molecule obtained from resveratrol against Candida albicans biofilm

Candida albicans can form biofilm on tissues and medical devices, becoming, in that case, less susceptible to antifungal agents. Treatment of candidiasis associated with the formation of C. albicans biofilms is restricted to echinocandins and lipid forms of amphotericin B. This study investigated the activity of micafungin and resveratrol modified molecule (EB487) against C. albicans biofilms. The anti-biofilm growth (Bgrowth) and anti-preformed biofilm (Bpreformed) activities of micafungin (0 to 3.94 μM) and EB487 (0 to 20.32 mM) were comparatively studied separately and combined, using XTT, flow cytometry and cell counts approaches. Concentrations causing 50% inhibition of the studied steps (IC50) were evaluated. When tested separately, IC50 Bgrowth was obtained for 4.8 mM and 0.13 μM of EB487 and micafungin respectively, and IC50 Bpreformed for 3.6 mM and 0.06 μM of EB487 and micafungin respectively. Micafungin used alone was not able to totally eradicate fungi. Micafungin combined with EB487 displayed synergistic activity (both anti-growth- and anti-preformed biofilm-activities). Optimal combination concentrations were EB487 (≤9.12 mM -strain ATCC 28367™ or ≤8.12 mM -strain CAI4-p), micafungin (≤0.05 μM for both) and caused a total eradication of fungi. Dose reduction indexes obtained using these concentrations were at least 9 (micafungin) and 3.2 (EB487) for both anti-biofilm growth- and anti-preformed biofilm-activities. Combinations indexes were consistently below one, demonstrating a synergistic relationship between micafungin and EB487 in these conditions. This study demonstrated the strong anti-biofilm activity of EB487 and highlighted its synergistic potential when combined with micafungin. EB487 is a promising semi-synthetic molecule with prophylactic and curative interests in fighting C. albicans biofilms.

A patent review of antibiofilm fungal drugs (2002-present)

Fungal biofilms, such as Candida albicans biofilms, are capable of surviving in hostile environments owing to their remarkable ability to adhere to surfaces and their tolerance to chemical interventions. Currently, therapeutic treatment options are few, making these biofilm-based infections problematic particularly due to their great tolerance to conventional antimicrobial drugs, thus causing serious health and economic problems. Therefore, the development of new drugs and antibiofilm specific therapies for the prevention and treatment of antifungal to eradicate biofilms are needed. This study was aimed at carrying out a patent review analysis to identify the innovation trends, and to explore the latest antifungal drugs and the specific therapeutic strategies available for the treatment of fungal biofilms. The present patent review was carried out using the Espacenet database, using the key words "biofilm and antifungal," from 2002 to December 2019. Through this review, it was possible to identify that most of the patent contents refer to new synthetic drugs derived from natural products and associations thereof with existing antifungal drugs. Methods and biomaterials for the treatment and prevention of fungal biofilms, mainly for C. albicans biofilms, which is the most isolated and studied fungal species, were also disclosed. The lack of scientific and technical information on the biofilm eradication subject is remarkable and further confirmed by the small number of patents identified in this survey.

Antibiofilm agent pterostilbene is able to enhance antibiotics action against Staphylococcus epidermidis

Pterostilbene (PTE) is a naturally occurring compound originally isolated from Pterocarpus spp. It has been widely used in traditional Indian medicine and later discovered to have various beneficial pharmacological effects such as antioxidant properties, hypoglycaemic or antitumor, and antimicrobial activity. This work is focused on demonstrating PTE synergistic effect with erythromycin and tetracycline to reduce their needed effective concentration for suppression of Staphylococcus epidermidis planktonic cells growth and biofilm formation. The secondary aim is to find these combinations effect on the production of its virulence factors. PTE was found to be effective in inhibition of its planktonic cells with MIC₈₀ values 25-37.5 mg l^-1. Simultaneously, it decreased the metabolic activity of biofilm cells and was especially effective on a clinical isolate (MBIC₈₀ = 35 mg l^-1) in contrast to the conventional antibiotics. In combination, PTE helped the antibiotics to overcome the tolerance of S. epidermidis biofilm cells (5 mg l^-1 of each antibiotic with 49 mg l^-1 PTE caused more than 85% inhibition of metabolic activity). It permeabilized cytoplasmic membrane of S. epidermidis cells and altered their surface hydrophobicity. Therefore, PTE has a great potential to enhance antibiotics action in the treatment of infections caused by this pathogen.

Antifungal Activity of Phenolic and Polyphenolic Compounds from Different Matrices of Vitis vinifera L. against Human Pathogens

Phenolic compounds, the most widely distributed class of natural products in the plants, show several biological properties including antifungal activity. Phenolics contained in grapes can be classified in two main groups, flavonoids and non-flavonoids compounds. Variability and yield extraction of phenolic and polyphenolic compounds from different matrices of Vitis vinifera depends of cultivar, climate, soil condition and process technology. Unripe grapes, berry skins and seeds, leaves, canes and stems and not-fermented and fermented pomaces represent large reusable and valuable wastes from agricultural and agro-industrial processes. This review summarizes studies that examine the extraction method, chemical characterization, and antifungal activity of phenolic and polyphenolic compounds from edible and non-edible V. vinifera matrices against human fungal pathogens. In the world, around one billion people have fungal diseases related to skin, nail or hair and around 150 million have systemic diseases caused by fungi. Few studies on antifungal activity of plant extracts have been performed. This review provides useful information for the application of V. vinifera phenolics in the field of antifungals for human use.

Stilbenoids: A Natural Arsenal against Bacterial Pathogens

The escalating emergence of resistant bacterial strains is one of the most important threats to human health. With the increasing incidence of multi-drugs infections, there is an urgent need to restock our antibiotic arsenal. Natural products are an invaluable source of inspiration in drug design and development. One of the most widely distributed groups of natural products in the plant kingdom is represented by stilbenoids. Stilbenoids are synthesised by plants as means of protection against pathogens, whereby the potential antimicrobial activity of this class of natural compounds has attracted great interest in the last years. The purpose of this review is to provide an overview of recent achievements in the study of stilbenoids as antimicrobial agents, with particular emphasis on the sources, chemical structures, and the mechanism of action of the most promising natural compounds. Attention has been paid to the main structure modifications on the stilbenoid core that have expanded the antimicrobial activity with respect to the parent natural compounds, opening the possibility of their further development. The collected results highlight the therapeutic versatility of natural and synthetic resveratrol derivatives and provide a prospective insight into their potential development as antimicrobial agents.

Combination of non-thermal plasma and subsequent antibiotic treatment for biofilm re-development prevention

The influence of non-thermal plasma (NTP) treatment on the prevention of antibiotic resistance of microbial biofilms was studied. Staphylococcus epidermidis and Escherichia coli bacteria and a yeast Candida albicans, grown on the surface of Ti-6Al-4V alloy used in the manufacture of prosthetic implants, were employed. Their biofilms were exposed to NTP produced by DC cometary discharge and subsequently treated with antibiotics commonly used for the treatment of infections caused by them: erythromycin (ERY), polymyxin B (PMB), or amphotericin B (AMB), respectively. All biofilms displayed significant reduction of their metabolic activity after NTP exposure, the most sensitive was S. epidermidis. The subsequent action of antibiotics caused significant decrease in the metabolic activity of S. epidermidis and E. coli, but not C. albicans, although the area covered by biofilm decreased in all cases. The combined effect of NTP with antibiotics was thus proved to be a promising strategy in bacterial pathogen treatment.

Effects of resveratrol on cariogenic virulence properties of Streptococcus mutans

Background

Streptococcus mutans is the principal etiological agent of human dental caries. The major virulence factors of S. mutans are acid production, acid tolerance, extracellular polysaccharide (EPS) synthesis and biofilm formation. The aim of this study is to evaluate the effect of resveratrol, a natural compound, on virulence properties of S. mutans.

Results

Resveratrol at sub-MIC levels significantly decreased acid production and acid tolerance, inhibited synthesis of water-soluble polysaccharide and water-insoluble polysaccharide, compromised biofilm formation. Related virulence gene expression (ldh, relA, gtfC, comDE) was down-regulated with increasing concentrations of resveratrol.

Conclusions

Resveratrol has an inhibitory effect on S. mutans cariogenic virulence properties and it represents a promising anticariogenic agent.

Anti-Candida Biofilm Activity of Pterostilbene or Crude Extract from Non-Fermented Grape Pomace Entrapped in Biopolymeric Nanoparticles

Polymeric nanoparticle-based carriers are promising agents to deliver drugs to cells. Vitis vinifera phenolic compounds are known for their antifungal activity against Candida albicans. The aim of the present study was to investigate the antifungal activity of pterostilbene or crude extracts from non-fermented grape pomace, entrapped in poly(lactic-co-glycolic) acid nanoparticles (NPs), with diameters of 50 and 150 nm, on Candida biofilm. The fluorescent probe coumarin 6 was used to study the uptake of poly(lactic-co-glycolic)acid (PLGA) NPs in planktonic cells and biofilm. The green fluorescent signal of coumarin 6 was observed in Candida biofilm after 24 and 48 hours. Both pterostilbene and crude pomace extract entrapped in NPs exerted a significantly higher anti-biofilm activity compared to their free forms. The entrapment efficiency of both pterostilbene and crude pomace extract in PLGA NPs was ~90%. At 16 µg/mL, pterostilbene loaded in PLGA NPs reduced biofilm formation of 63% and reduced mature biofilm of 50%. Moreover, at 50 µg/mL, the pomace extract loaded in NPs reduced mature biofilm of 37%. These results strongly suggest that PLGA NPs are promising nanodevices for the delivery of antifungal drugs as the crude grape pomace extract, a by-product of white wine making.

Stilbene derivatives as new perspective in antifungal medicinal chemistry

The high incidence and mortality of invasive fungal infections and serious drug resistance have become a global public health issue. There is an urgent need for alternative antimicrobials to control fungal infections and targeting it by antifungal substances from the natural sources represents a promising new strategy for the development of novel antifungal agents. Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a phytoalexin produced by plant species in response to environmental stress or pathogenic attacks. It has many known and potential therapeutic applications in human general homeostasis; it mediates a great number of biological responses relevant for human health such as anticancer, cardio and neuroprotective, antioxidant, and antimicrobial activities. Resveratrol is a natural antifungal agent, therefore it can be considered as a scaffold for designing structural relatives potentially capable of mediating more intense responses in a more specific way. Also, stilbenes produced by several plants may be useful lead structure for the chemical synthesis of antifungal. Their antifungal potential represents a useful solution to the drug resistance and side effect complications that occur after pharmacological treatment of infectious diseases. The purpose of this review is to present an overview on resveratrol derivatives, both natural and synthetic, with antifungal activity and summarize the chemical structure and the therapeutic versatility of stilbene-containing compounds.