Chemical and botanical characterization of Chilean propolis and biological activity on cariogenic bacteria Streptococcus mutans and Streptococcus sobrinus

Targeting glucosyltransferases to combat dental caries: Current perspectives and future prospects

The emergence of antimicrobial resistance within bacterial communities poses formidable challenges to existing therapeutic strategies aimed at mitigating biofilm-mediated infections. Recent advancements in this domain have spurred the development of targeted antimicrobial agents, designed to selectively eradicate the primary etiological agents while preserving the beneficial microbial diversity of the oral cavity. Targeting glucosyltransferases (GTFs), which play crucial roles in dental biofilm formation, offers a precise strategy to inhibit extracellular polysaccharide synthesis without compromising oral microbiota. This review article delves into the intricate mechanisms underlying dental caries, with a specific focus on the role of GTFs, enzymes produced by S. mutans. It further provides an overview of current research on GTF inhibitors, exploring their mechanisms of action, efficacy, and potential applications in clinical practice. Furthermore, it discusses the challenges and opportunities in the development of novel GTF inhibitors, emphasizing the need for innovative approaches to combat biofilm-mediated oral diseases effectively.

Algerian Propolis from Distinct Geographical Locations: Chemical Profiles, Antioxidant Capacity, Cytotoxicity and Inhibition of 5-Lipoxygenase Product Biosynthesis

Propolis was collected from honeybee hives in three geographically distinct Algerian climates and extracts were characterized for composition and bioactivity. Bees were identified as native subspecies using an in-silico DraI mtDNA COI-COII test. Over 20 compounds were identified in extracts by LC-MS. Extracts from the Medea region were more enriched in phenolic content (302±28 mg GAE/g of dry extract) than those from Annaba and Ghardaia regions. Annaba extracts had the highest flavonoid content (1870±385 mg QCE/g of dry extract). Medea extracts presented the highest free-radical scavenging activity (IC50=13.5 μg/mL) using the DPPH radical assay while Ghardaia extracts from the desert region were weak (IC50>100 μg/mL). Antioxidant activities measured using AAPH oxidation of linoleic acid were similar in all extracts with IC50 values ranging from 2.9 to 4.9 μg/mL. All extracts were cytotoxic (MTT assay) and proapoptotic (Annexin-V) against human leukemia cell lines in the low μg/mL range, although the Annaba extract was less active against the Reh cell line. Extracts inhibited cellular 5-lipoxygenase product biosynthesis with IC50 values ranging from 0.6 to 3.2 μg/mL. Overall, examined propolis extracts exhibited significant biological activity that warrant further characterization in cellular and in vivo models.

Influence of the Encapsulating Agent on the Bioaccessibility of Phenolic Compounds from Microencapsulated Propolis Extract during In Vitro Gastrointestinal Digestion

The aim of this work is to develop different encapsulated propolis ingredients by spray-drying and to evaluate their bioaccessibility using simulated in vitro digestion. To achieve these goals, first, microparticles of a propolis extract with inulin as the coating polymer were prepared under the optimal conditions previously determined. Then, a fraction of inulin was replaced with other encapsulating agents, namely sodium alginate, pectin, and chitosan, to obtain different ingredients with controlled release properties in the gastrointestinal tract. The analysis of the phenolic profile in the propolis extract and microparticles showed 58 compounds tentatively identified, belonging mainly to phenolic acid derivatives and flavonoids. Then, the behavior of the free extract and the formulated microparticles under gastrointestinal conditions was studied through an in vitro gastrointestinal digestion process using the INFOGEST protocol. Digestion of the free extract resulted in the degradation of most compounds, which was minimized in the encapsulated formulations. Thus, all developed microparticles could be promising strategies for improving the stability of this bioactive extract under gastrointestinal conditions, thereby enhancing its beneficial effect.

Propolis as a Cariostatic Agent in Lozenges and Impact of Storage Conditions on the Stability of Propolis

Propolis is known as a source of compounds with strong antibacterial activity. Due to the antibacterial effect against streptococci of the oral cavity, it seems to be a useful agent in decreasing the accumulation of dental plaque. It is rich in polyphenols which are responsible for a beneficial impact on the oral microbiota and antibacterial effect. The aim of the study was to evaluate the antibacterial effect of Polish propolis against cariogenic bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined on cariogenic streptococci related to the occurrence of dental caries. Lozenges based on xylitol, glycerin, gelatin, water, and ethanol extract of propolis (EEP) were prepared. The effect of prepared lozenges on cariogenic bacteria was assessed. Propolis was compared to chlorhexidine which is used in dentistry as the gold standard. In addition, the prepared propolis formulation was stored under stress conditions to assess the influence of physical conditions (i.e., temperature, relative humidity, and UV radiation). In the experiment, thermal analyses were also performed to evaluate the compatibility of propolis with the substrate used to create the base of lozenges. The observed antibacterial effect of propolis and prepared lozenges with EEP may suggest directing subsequent research on prophylactic and therapeutic properties decreasing the accumulation of dental plaque. Therefore, it is worth highlighting that propolis may play an important role in the management of dental health and bring advantages in preventing periodontal diseases and caries as well as dental plaque. The colorimetric analyses carried out in the CIE L*a*b* system, microscopic examinations, and TGA/DTG/c-DTA measurements indicate the unfavorable effect of the tested storage conditions on the lozenges with propolis. This fact is particularly evident for lozenges stored under stress conditions, i.e., 40 °C/75% RH/14 days, and lozenges exposed to UVA radiation for 60 min. In addition, the obtained thermograms of the tested samples indicate the thermal compatibility of the ingredients used to create the formulation of lozenges.

Therapeutic Potential of Flavonoids and Tannins in Management of Oral Infectious Diseases-A Review

Medicinal plants are rich sources of valuable molecules with various profitable biological effects, including antimicrobial activity. The advantages of herbal products are their effectiveness, relative safety based on research or extended traditional use, and accessibility without prescription. Extensive and irrational usage of antibiotics since their discovery in 1928 has led to the increasing expiration of their effectiveness due to antibacterial resistance. Now, medical research is facing a big and challenging mission to find effective and safe antimicrobial therapies to replace inactive drugs. Over the years, one of the research fields that remained the most available is the area of natural products: medicinal plants and their metabolites, which could serve as active substances to fight against microbes or be considered as models in drug design. This review presents selected flavonoids (such as apigenin, quercetin, kaempferol, kurarinone, and morin) and tannins (including oligomeric proanthocyanidins, gallotannins, ellagitannins, catechins, and epigallocatechin gallate), but also medicinal plants rich in these compounds as potential therapeutic agents in oral infectious diseases based on traditional usages such as Agrimonia eupatoria L., Hamamelis virginiana L., Matricaria chamomilla L., Vaccinium myrtillus L., Quercus robur L., Rosa gallica L., Rubus idaeus L., or Potentilla erecta (L.). Some of the presented compounds and extracts are already successfully used to maintain oral health, as the main or additive ingredient of toothpastes or mouthwashes. Others are promising for further research or future applications.

Antibacterial effects of natural compounds on biofilm formation of Streptococcus mutans

Streptococcus mutans is the main cariogenic pathogen in the oral cavity, considered to contribute toward oral diseases. S. mutans is predominantly entrapped in plaque biofilms.

OBJECTIVES

In this study, we surveyed the antibacterial activity of natural compounds in terms of the biofilm production of S. mutans.

MATERIAL AND METHODS

We extracted the studies related to natural compounds affected on S. mutans biofilm from different databases.

RESULTS

Disruption of S. mutans viability in biofilms by a potent new pharmacological factor could inhibit and remove cavities. Various antibacterial agents are needed to destroy biofilms that remove both pathogens and commensal bacteria, and also exert inhibitory effects on many bacterial species.

CONCLUSIONS

An effective therapeutic agent for dental caries has to be capable of removing pathogens and their biofilms. Specific virulence attributes of S. mutans exist; hence, natural compounds that have excellent properties to combat such pathogens need to be selected.

Therapeutic Potential of Honey and Propolis on Ocular Disease

Honey and propolis have recently become the key target of attention for treating certain diseases and promoting overall health and well-being. A high content of flavonoids and phenolic acids found in both honey and propolis contributes to the antioxidant properties to scavenge free radicals. Honey and propolis also exhibited antibacterial effects where they act in two ways, namely the production of hydrogen peroxide (H2O2) and gluconic acids following the enzymatic activities of glucose oxidase, which exerts oxidative damage on the bacteria. Additionally, the anti-inflammatory effects of honey and propolis are mainly by reducing proinflammatory factors such as interleukins and tumor necrosis factor alpha (TNF-α). Their effects on pain were discovered through modulation at a peripheral nociceptive neuron or binding to an opioid receptor in the higher center. The aforementioned properties of honey have been reported to possess potential therapeutic topical application on the exterior parts of the eyes, particularly in treating conjunctivitis, keratitis, blepharitis, and corneal injury. In contrast, most of the medicinal values of propolis are beneficial in the internal ocular area, such as the retina, optic nerve, and uvea. This review aims to update the current discoveries of honey and propolis in treating various ocular diseases, including their antioxidant, anti-inflammatory, antibacterial, and anti-nociceptive properties. In conclusion, research has shown that propolis and honey have considerable therapeutic promise for treating various eye illnesses, although the present study designs are primarily animal and in vitro studies. Therefore, there is an urgent need to translate this finding into a clinical setting.

Caffeic Acid Phenethyl Ester (CAPE) Inhibits Cross-Kingdom Biofilm Formation of Streptococcus mutans and Candida albicans

Streptococcus mutans and Candida albicans exhibit strong cariogenicity through cross-kingdom biofilm formation during the pathogenesis of dental caries. Caffeic acid phenethyl ester (CAPE), a natural compound, has potential antimicrobial effects on each species individually, but there are no reports of its effect on this dual-species biofilm. This study aimed to explore the effects of CAPE on cariogenic biofilm formation by S. mutans and C. albicans and the related mechanisms. The effect of CAPE on planktonic cell growth was investigated, and crystal violet staining, the anthrone-sulfuric acid assay and confocal laser scanning microscopy were used to evaluate biofilm formation. The structures of the formed biofilms were observed using scanning electron microscopy. To explain the antimicrobial effect of CAPE, quantitative real-time PCR (qRT-PCR) was applied to monitor the relative expression levels of cariogenic genes. Finally, the biocompatibility of CAPE in human oral keratinocytes (HOKs) was evaluated using the CCK-8 assay. The results showed that CAPE suppressed the growth, biofilm formation and extracellular polysaccharides (EPS) synthesis of C. albicans and S. mutans in the coculture system of the two species. The expression of the gtf gene was also suppressed by CAPE. The efficacy of CAPE was concentration dependent, and the compound exhibited acceptable biocompatibility. Our research lays the foundation for further study of the application of the natural compound CAPE as a potential antimicrobial agent to control dental caries-associated cross-kingdom biofilms. IMPORTANCE Severe dental caries is a multimicrobial infectious disease that is strongly induced by the cross-kingdom biofilm formed by S. mutans and C. albicans. This study aimed to investigate the potential of caffeic acid phenethyl ester (CAPE) as a natural product in the prevention of severe caries. This study clarified the inhibitory effect of CAPE on cariogenic biofilm formation and the control of cariogenic genes. It deepens our understanding of the synergistic cariogenic effect of S. mutans and C. albicans and provides a new perspective for the prevention and control of dental caries with CAPE. These findings may contribute to the development of CAPE as a promising antimicrobial agent targeting this caries-related cross-kingdom biofilm.

An Insight into Anticancer Effect of Propolis and Its Constituents: A Review of Molecular Mechanisms

Propolis is a natural compound collected by honeybees from different parts of plants. Honeybees produce a sticky component besides honey by mixing the tree resin and other botanical sources with saliva called propolis or bee glue. Propolis was traditionally used as a wound healing substance, cosmetic, medicine, and many other conditions. Till now, there is no definite curable treatment for most cancers and chemotherapeutic drugs and drugs used for targeted therapies have serious side effects. According to a recent research, natural products are becoming increasingly essential in cancer prevention. Natural products are a great source of potential therapeutic agents, especially in the treatment of cancer. Previous studies have reported that the presence of caffeic acid phenethyl ester (CAPE), artepillin C, and chrysin is responsible for the anticancer potential of propolis. Most of the previous studies suggested that propolis and its active compounds inhibit cancer progression by targeting multiple signaling pathways including phosphoinositide 3-kinases (PI3K)/Akt and mitogen-activated protein kinase (MAPK) signaling molecules, and induce cell cycle arrest. Induction of apoptosis by propolis is mediated through extrinsic and intrinsic apoptotic pathways. The aim of this review is to highlight and summarize the molecular targets and anticancer potential of propolis and its active compounds on cell survival, proliferation, metastasis, and apoptosis in cancer cells.

Influence of Propolis Extract (Caffeic Acid Phenethyl Ester) Addition on the Candida albicans Adhesion and Surface Properties of Autopolymerized Acrylic Resin

Background. Denture stomatitis has been linked to the adhesion and proliferation of Candida albicans (C. albicans) on denture bases, which is a common and recurrent problem in denture wearers. The current study aimed to evaluate the effect of incorporating caffeic acid phenethyl ester (CAPE) into autopolymerized polymethyl methacrylate (PMMA) acrylic resin on C. albicans adhesion, surface roughness, and hardness as well as the correlation between tested properties. Methods. Autopolymerized acrylic resin discs (N = 100, 50/C. albicans adhesion; 50/C. albicans surface roughness and hardness test) were fabricated in dimensions 15 × 2.5 mm, samples were categorized into 5 groups (n = 10) based on CAPE concentrations; unmodified (control), 2.5, 5, 10 and 15% wt of acrylic powder. Specimens were stored in distilled water for 48 h at 37°C. C. albicans adhesion was evaluated via direct culture method. Profilometer and Vickers hardness tester were used for surface roughness and hardness measurement. Post hoc Tukey’s HSD with ANOVA test was performed to compare the difference of means amongst groups. $P$ values were statistically significant at ≤0.05. Results. The addition of 2.5% of CAPE to PMMA has significantly reduced C. albicans counts in comparison to higher CAPE concentrations ( $p<0.001$ ). As for surface roughness, it was noticed that it increased with increased CAPE concentrations ( $p<0.0001$ ). While surface hardness decreased as CAPE concentrations increased ( $p<0.0001$ ). All tested properties showed a significant difference amongst groups for C. albicans colony count and surface parameters. Conclusion. The addition of 2.5% of CAPE to PMMA acrylic resin significantly decreased C. albicans count compared to higher CAPE concentrations. CAPE can be used as an adjunct in the prevention of DS by incorporating in the PMMA acrylic resin.

Propolis: Properties and composition, health benefits and applications in fish nutrition

Propolis is a viscous, waxy, resinous substance that is produced from the exudates of flowers and buds by the action of salivary enzymes of honey bees. Propolis may differ in color (brown, red or green), with color being influenced by the chemical composition and age of the product. Propolis has a special distinctive odor owing to the high concentration of volatile essential oils. It is composed of 5% pollen grains, 10% essential and aromatic oils, 30% wax, 50% resin and balsams, and other minor trace substances. Natural propolis products may be useful for a range of applications in aquaculture systems instead of relying on the application of synthetic compounds to manage many ailments that affect business profitability. It has been reported in several studies that propolis enhances performance, economics, immunity response and disease resistance in different fish species. This present review discusses the functional actions of propolis and the prospects of its use as an antimicrobial, antioxidant, immune-modulatory, antiseptic, antiparasitic, anti-inflammatory and food additive in aquaculture production. In summary, propolis could be a natural supplement that has the potential to improve fish health status and immunity thereby enhancing growth and productivity of the fish industry as well as economic efficiency.

Geographic Area of Collection Determines the Chemical Composition and Antimicrobial Potential of Three Extracts of Chilean Propolis

The biological properties of chilean propolis have been described and include antibacterial, antifungal and antibiofilm activities. Propolis has a strong antimicrobial potential. Clinical experiences with synthetic antibiotics indicated the need to discover new sources of bioactive compounds associated with ethnopharmacological knowledge or natural sources such as propolis. The microscopic analysis of pollen grains from plants allows us to determine the botanical origin of the propolis samples. In Angol, sample pollen grains were obtained from fodder plants (Sorghum bicolor; Lotus sp.) and trees, such as Acacia sp., Pinus radiata, Eucalyptus sp. and Salix babylonica. Propolis from the Maule region contains pollen grains from endemic plants such as Quillaja saponaria. Finally, the sample obtained from Melipilla presented a wider variety of pollen extracted from vegetable species.Colorimetric assays performed to quantify the total polyphenols present in Chilean propolis samples established that PCP2 (Angol sample) showed high amounts of phenolics compounds, with significant statistical differences in comparison with the other samples. The main compounds identified were pinocembrin, quercetin and caffeic acid phenethyl ester (CAPE). The Angol sample showed a high content of polyphenols.Studies that determine the influence of geographical and floral variables on the chemical composition of propolis are a valuable source of information for the study of its biological properties.

Experimental Evidence for Therapeutic Potentials of Propolis

Propolis is produced by honeybees from materials collected from plants they visit. It is a resinous material having mixtures of wax and bee enzymes. Propolis is also known as bee glue and used by bees as a building material in their hives, for blocking holes and cracks, repairing the combs and strengthening their thin borders. It has been extensively used since ancient times for different purposes in traditional human healthcare practices. The quality and composition of propolis depend on its geographic location, climatic zone and local flora. The New Zealand and Brazilian green propolis are the two main kinds that have been extensively studied in recent years. Their bioactive components have been found to possess a variety of therapeutic potentials. It was found that Brazilian green propolis improves the cognitive functions of mild cognitive impairments in patients living at high altitude and protects them from neurodegenerative damage through its antioxidant properties. It possesses artepillin C (ARC) as the key component, also known to possess anticancer potential. The New Zealand propolis contains caffeic acid phenethyl ester (CAPE) as the main bioactive with multiple therapeutic potentials. Our lab performed in vitro and in vivo assays on the extracts prepared from New Zealand and Brazilian propolis and their active ingredients. We provided experimental evidence that these extracts possess anticancer, antistress and hypoxia-modulating activities. Furthermore, their conjugation with γCD proved to be more effective. In the present review, we portray the experimental evidence showing that propolis has the potential to be a candidate drug for different ailments and improve the quality of life.

Are propolis extracts potential pharmacological agents in human oral health? - A scoping review and technology prospecting

ETHNOPHARMACOLOGICAL RELEVANCE

The antimicrobial potential of propolis - a honey bee product - was correlated with its traditional use as a natural medicine, mainly known for antimicrobial and antioxidant properties. Moreover, research on natural products in dentistry has increased in recent years in the search for products with greater therapeutic activity, lower toxicity, better biocompatibility, and more affordable cost to the population.

OBJECTIVE

Considering that the beneficial effect of propolis is acknowledged for several oral conditions, this study aimed to synthesize the research and technological forecasts of existing evidence on the use of propolis extract as a potential antimicrobial agent in dentistry.

METHODS

Studies were identified through an investigation in the PubMed, Web of Science, Scopus, and Scielo electronic databases. Additionally, the following patent databases were screened: Google Patents, WIPO, INPI, Espacenet, and Questel Orbit. The data were tabulated and analyzed using Microsoft Office Excel 2013 and Questel Orbit.

RESULTS

A total of 174 scientific articles and 276 patents fulfilled all the criteria and were included in the investigation. The highest number of patents (n = 144) was produced by China. Additionally, the most prevalent studies were performed on an experimental basis (72%), followed by clinical studies (n = 27) and review articles (n = 21). The effect of using propolis has been extensively observed in oral care products, periodontics, pathology, and cariology, among other dental specialties.

CONCLUSION

It was possible to identify the current scientific and technological scenario of the application of propolis in dentistry, with the number of patents increasing in recent years. However, all studies related to the use of propolis in dentistry have shown a potentially safe antimicrobial agent in an extensive field of application.

Caffeic Acid and Its Derivatives: Antimicrobial Drugs toward Microbial Pathogens

Caffeic acid is a plant-derived compound that is classified as hydroxycinnamic acid which contains both phenolic and acrylic functional groups. Caffeic acid has been greatly employed as an alternative strategy to combat microbial pathogenesis and chronic infection induced by microbes such as bacteria, fungi, and viruses. Similarly, several derivatives of caffeic acid such as sugar esters, organic esters, glycosides, and amides have been chemically synthesized or naturally isolated as potential antimicrobial agents. To overcome the issue of water insolubility and poor stability, caffeic acid and its derivative have been utilized either in conjugation with other bioactive molecules or in nanoformulation. Besides, caffeic acid and its derivatives have also been applied in combination with antibiotics or photoirradiation to achieve a synergistic mode of action. The present review describes the antimicrobial roles of caffeic acid and its derivatives exploited either in free form or in combination or in nanoformulation to kill a diverse range of microbial pathogens along with their mode of action. The chemistry employed for the synthesis of the caffeic acid derivatives has been discussed in detail as well.

Phytochemicals, mineral contents, antioxidants, and antimicrobial activities of propolis produced by Brunei stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami

The present study focused on the evaluation of phytochemical properties, essential mineral elements, and heavy metals contained in raw propolis produced by stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami found in the same ecological conditions and environment in Brunei Darussalam. The results indicated that propolis of the three stingless bee species mainly consisted of lipids (45.60–47.86%) and very low carbohydrate (0.17–0.48%) and protein contents (0.18–1.18%). The propolis was rich in mineral elements, thus good sources of minerals, while they contained low concentrations of all heavy metals. Propolis of the different bee species could be distinguished based on their mineral compositions. The vibrational and absorption spectra suggested that propolis contains π-conjugated aliphatic and aromatic compounds as well as aromatic acids having amine, ester, carbonyl, alkyl, and hydroxyl functional groups which might be attributed to the presence of phenolic and flavonoid compounds. The antioxidant capacity of the propolis, based on radical scavenging activity of their ethanol extract, was in line with their total phenolic content. The ethanol extract of the propolis also showed antimicrobial activities against four bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa). The propolis showed slightly higher antibacterial activity against Gram-positive (B. subtilis and S. aureus) bacteria, indicating that the antimicrobial active compounds could be associated with flavonoids, which were quantified to be approximately comparable in all the propolis.

Antibacterial Effect of Caffeic Acid Phenethyl Ester on Cariogenic Bacteria and Streptococcus mutans Biofilms

Dental caries is the most common disease in the human mouth. Streptococcus mutans is the primary cariogenic bacterium. Propolis is a nontoxic natural product with a strong inhibitory effect on oral cariogenic bacteria. The polyphenol-rich extract from propolis inhibits S. mutans growth and biofilm formation, as well as the genes involved in virulence and adherence, through the inhibition of glucosyltransferases (GTF). However, because the chemical composition of propolis is highly variable and complex, the mechanism of its antimicrobial action and the active compound are controversial and not completely understood. Caffeic acid phenethyl ester (CAPE) is abundant in the polyphenolic compounds from propolis, and it has many pharmacological effects. In this study, we investigated the antibacterial effects of CAPE on common oral cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus, Actinomyces viscosus, and Lactobacillus acidophilus) and its effects on the biofilm-forming and cariogenic abilities of S. mutans CAPE shows remarkable antimicrobial activity against cariogenic bacteria. Moreover, CAPE also inhibits the formation of S. mutans biofilms and their metabolic activity in mature biofilms. Furthermore, CAPE can inhibit the key virulence factors of S. mutans associated with cariogenicity, including acid production, acid tolerance, and the bacterium's ability to produce extracellular polysaccharides (EPS), without affecting bacterial viability at subinhibitory levels. In conclusion, CAPE appears to be a new agent with anticariogenic potential, not only via inhibition of the growth of cariogenic bacteria.

Evaluation of Alternative Methods to Assess the Biological Properties of Propolis on Metabolic Activity and Biofilm Formation in Streptococcus mutans

Several biological activities have been reported for the Chilean propolis, among their antimicrobial and antibiofilm properties, due to its high polyphenol content. In this study, we evaluate alternative methods to assess the effect of Chilean propolis on biofilm formation and metabolic activity of Streptococcus mutans (S. mutans), a major cariogenic agent in oral cavity. Biofilm formation was studied by using crystal violet and by confocal microscopy. The metabolic activity of biofilm was evaluated by MTT and by flow cytometry analysis. The results show that propolis reduces biofilm formation and biofilm metabolic activity in S. mutans. When the variability of the methods to measure biofilm formation was compared, the coefficient of variation (CV) fluctuated between 12.8 and 23.1% when using crystal violet methodology. On the other hand, the CV ranged between 2.2 and 3.3% with confocal microscopy analysis. The CV for biofilm's metabolic activity measured by MTT methodology ranged between 5.0 and 11.6%, in comparison with 1.9 to 3.2% when flow cytometry analysis was used. Besides, it is possible to conclude that the methods based on colored compounds presented lower precision to study the effect of propolis on biofilm properties. Therefore, we recommend the use of flow cytometry and confocal microscopy in S. mutans biofilm analysis.

Physicochemical analyses, antioxidant, antibacterial, and toxicity of propolis particles produced by stingless bee Heterotrigona itama found in Brunei Darussalam

In this study, the physicochemical, antioxidant, antibacterial properties, and the toxicity of propolis particles produced by stingless bee Heterotrigona itama found in Brunei Darussalam were investigated. Propolis particles of different sizes were extracted from raw propolis using various volume fractions of ethanol in water. Spectroscopic analyses were utilized to characterize the chemical structures, functional groups, as well as absorbance and fluorescence properties. The total antioxidant capacity of propolis particles, which was assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, was found to increase with volume fraction of ethanol. The maximum antioxidant capacity was as high as 317.65 mg ascorbic acid equivalent per gram of propolis particles. All of the propolis particles showed antibacterial activity against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The diameters of the inhibition zone were either significantly higher or equivalent to those of two standard antibiotics (rifampicin and streptomycin), suggesting strong antibacterial activity. The toxicity studies of propolis particles against Caenorhabditis elegans revealed that they are non-toxic after 24 h exposure. Overall findings suggest that H. itama propolis particles are not only an important source of natural antioxidants that could be beneficial for human health, but they have potentials as antimicrobial against bacteria.

Use of nPSi-βCD Composite Microparticles for the Controlled Release of Caffeic Acid and Pinocembrin, Two Main Polyphenolic Compounds Found in a Chilean Propolis

Propolis is widely recognized for its various therapeutic properties. These are attributed to its rich composition in polyphenols, which exhibit multiple biological properties (e.g., antioxidant, anti-inflammatory, anti-angiogenic). Despite its multiple benefits, oral administration of polyphenols results in low bioavailability at the action site. An alternative to face this problem is the use of biomaterials at nano-micro scale due to its high versatility as carriers and delivery systems of various drugs and biomolecules. The aim of this work is to determine if nPSi-βCD microparticles are a suitable material for the load and controlled release of caffeic acid (CA) and pinocembrin (Pin), two of the main components of a Chilean propolis with anti-atherogenic and anti-angiogenic activity. Polyphenols and nPSi-βCD microparticles cytocompatibility studies were carried out with human umbilical vein endothelial cells (HUVECs). Results from physicochemical characterization demonstrated nPSi-βCD microparticles successfully retained and controlled release CA and Pin. Furthermore, nPSi-βCD microparticles presented cytocompatibility with HUVECs culture at concentrations of 0.25 mg/mL. These results suggest that nPSi-βCD microparticles could safely be used as an alternate oral delivery system to improve controlled release and bioavailability of CA or Pin-and eventually other polyphenols-thus enhancing its therapeutic effect for the treatment of different diseases.

Antibacterial Properties of Propolis

Researchers are continuing to discover all the properties of propolis due to its complex composition and associated broad spectrum of activities. This review aims to characterize the latest scientific reports in the field of antibacterial activity of this substance. The results of studies on the influence of propolis on more than 600 bacterial strains were analyzed. The greater activity of propolis against Gram-positive bacteria than Gram-negative was confirmed. Moreover, the antimicrobial activity of propolis from different regions of the world was compared. As a result, high activity of propolis from the Middle East was found in relation to both, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) strains. Simultaneously, the lowest activity was demonstrated for propolis samples from Germany, Ireland and Korea.

Antimicrobial and Antibiofilm Activity against Streptococcus mutans of Individual and Mixtures of the Main Polyphenolic Compounds Found in Chilean Propolis

Dental caries is multifactorial disease and an important health problem worldwide. Streptococcus mutans is considered as a major cariogenic agent in oral cavity. This bacteria can synthetize soluble and insoluble glucans from sucrose by glucosyltransferases enzymes and generate stable biofilm on the tooth surface. Biological properties of Chilean propolis have been described and it includes antimicrobial, antifungal, and antibiofilm activities. The main goal of this study was to quantify the concentrations of main flavonoids presents in Chilean propolis and compare some biological properties such as antimicrobial and antibiofilm activity of individual compounds and the mixture of this compounds, against S. mutans cultures. Chilean propolis was studied and some polyphenols present in this extract were quantified by HPLC-DAD using commercial standards of apigenin, quercetin, pinocembrin, and caffeic acid phenethyl ester (CAPE). MIC for antimicrobial activity was determined by serial dilution method and biofilm thickness on S. mutans was quantified by confocal microscopy. Pinocembrin, apigenin, quercetin, and caffeic acid phenethyl ester (CAPE) are the most abundant compounds in Chilean propolis. These polyphenols have strong antimicrobial and antibiofilm potential at low concentrations. However, pinocembrin and apigenin have a greater contribution to this action. The effect of polyphenols on S. mutans is produced by a combination of mechanisms to decrease bacterial growth and affect biofilm proliferation due to changes in their architecture.

Inhibition of Oral Pathogens Adhesion to Human Gingival Fibroblasts by Wine Polyphenols Alone and in Combination with an Oral Probiotic

Several benefits have been described for red wine polyphenols and probiotic strains in the promotion of colonic metabolism and health. On the contrary, knowledge about their role in the management of oral health is still scarce. In this work, the antiadhesive capacity of selected red wine polyphenols and oenological extracts against the oral pathogens Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mutans in an in vitro model of human gingival fibroblasts has been explored as well as their complementary action with the candidate oral probiotic Streptococcus dentisani. Results highlighted the antiadhesive capacity of caffeic and p-coumaric acids as well as grape seed and red wine oenological extracts. Both, caffeic and p-coumaric acids increased their inhibition potential against S. mutans adhesion when combined with S. dentisani. Additionally, UHPLC-MS/MS analysis demonstrated the oral metabolism of wine phenolics due to both, cellular and bacterial activity.

Antioxidant, Cytotoxic, and Toxic Activities of Propolis from Two Native Bees in Brazil: Scaptotrigona depilis and Melipona quadrifasciata anthidioides

Propolis is a natural mixture of compounds produced by various bee species, including stingless bees. This compound has been shown to exhibit antioxidant, antiproliferative, and antitumor activities. The present study aimed to determine the chemical constituents as well as the antioxidant, cytotoxic, and toxic activities of ethanol extracts of propolis obtained from the stingless bees Scaptotrigona depilis and Melipona quadrifasciata anthidioides, which are found in Brazil. Phytosterols, terpenes, phenolic compounds, and tocopherol were identified in the ethanol extracts of propolis (EEPs) in different concentrations. The compounds stigmasterol, taraxasterol, vanilic acid, caffeic acid, quercetin, luteolin, and apigenin were found only in EEP-M. The EEPs were able to scavenge the free radicals 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and protected human erythrocytes against lipid peroxidation, with the latter effect being demonstrated by their antihemolytic activity and inhibition of malondialdehyde formation. The EEPs showed cytotoxic activity against erythroleukemic cells and necrosis was the main mechanism of death observed. In addition, the concentrations at which the EEPs were cytotoxic were not toxic against Caenorhabditis elegans. In this context, it is concluded that EEP-S and EEP-M show antioxidant and cytotoxic activities and are promising bioactive mixtures for the control of diseases associated with oxidative stress and tumor cell proliferation.

Polyphenols from Chilean Propolis and Pinocembrin Reduce MMP-9 Gene Expression and Activity in Activated Macrophages

Polyphenols from diverse sources have shown anti-inflammatory activity. In the context of atherosclerosis, macrophages play important roles including matrix metalloproteinases synthesis involved in degradation of matrix extracellular components affecting the atherosclerotic plaque stability. We prepared a propolis extract and pinocembrin in ethanol solution. Propolis extract was chemically characterized using LC-MS. The effect of treatments on gene expression and proteolytic activity was measured in vitro using murine macrophages activated with LPS. Cellular toxicity associated with both treatments and the vehicle was determined using MTT and apoptosis/necrosis detection assays. MMP-9 gene expression and proteolytic activity were measured using qPCR and zymography, respectively. Thirty-two compounds were identified in the propolis extract, including pinocembrin among its major components. Treatment with either ethanolic extract of propolis or pinocembrin inhibits MMP-9 gene expression in a dose-dependent manner. Similarly, an inhibitory effect was observed in proteolytic activity. However, the effect showed by ethanolic extract of propolis was higher than the effect of pinocembrin, suggesting that MMP-9 inhibition results from a joint contribution between the components of the extract. These data suggest a potential role of polyphenols from Chilean propolis in the control of extracellular matrix degradation in atherosclerotic plaques.

Polyphenol-Rich Extract from Propolis Reduces the Expression and Activity of Streptococcus mutans Glucosyltransferases at Subinhibitory Concentrations

Tooth decay is an infectious disease, whose main causative agent identified is Streptococcus mutans (S. mutans). Diverse treatments have been used to eradicate this microorganism, including propolis. To date, it has been shown that polyphenols from Chilean propolis inhibit S. mutans growth and biofilm formation. However, the molecular mechanisms underlying this process are unclear. In the present study, we assessed the effect of Chilean propolis on the expression and activity of the glycosyltransferases enzymes and their related genes. Polyphenol-rich extract from propolis inhibited gene expression of glycosyltransferases (GtfB, GtfC, and GtfD) and their related regulatory genes, for example, VicK, VicR, and CcpA. Moreover, the treatment inhibited glucosyltransferases activity measured by the formation of sucrose-derived glucans. Additionally, an inhibitory effect was observed in the expression of SpaP involved in sucrose-independent virulence of S. mutans. In summary, our results suggest that Chilean propolis has a dose-dependent effect on the inhibition of genes involved in S. mutans virulence and adherence through the inhibition of glucosyltransferases, showing an anticariogenic potential of polyphenols from propolis beyond S. mutans growth inhibition.

Fast Differential Analysis of Propolis Using Surface Desorption Atmospheric Pressure Chemical Ionization Mass Spectrometry

Mass spectral fingerprints of 24 raw propolis samples, including 23 from China and one from the United States, were directly obtained using surface desorption atmospheric pressure chemical ionization mass spectrometry (SDAPCI-MS) without sample pretreatment. Under the optimized experimental conditions, the most abundant signals were detected in the mass ranges of 70 to 500 m/z and 200 to 350 m/z, respectively. Principal component analyses (PCA) for the two mass ranges showed similarities in that the colors had a significant correlation with the first two PCs; in contrast there was no correlation with the climatic zones from which the samples originated. Analytes such as chrysin, pinocembrin, and quercetin were detected and identified using multiple stage mass spectrometry within 3 min. Therefore, SDAPCI-MS can be used for rapid and reliable high-throughput analysis of propolis.

Antibiofilm Activity of Chilean Propolis on Streptococcus mutans Is Influenced by the Year of Collection

The chemical composition of propolis varies according to factors that could have an influence on its biological properties. Polyphenols from propolis have demonstrated an inhibitory effect on Streptococcus mutans growth. However, it is not known if different years of propolis collection may affect its activity. We aimed to elucidate if the year of collection of propolis influences its activity on Streptococcus mutans. Polyphenol-rich extracts were prepared from propolis collected in three different years, characterized by LC-MS and quantified the content of total polyphenols and flavonoids groups. Finally, was evaluated the antibacterial effect on Streptococcus mutans and the biofilm formation. Qualitative differences were observed in total polyphenols, flavones, and flavonols and the chemical composition between the extracts, affecting the strength of inhibition of biofilm formation but not the antimicrobial assays. In conclusion, chemical composition of propolis depends on the year of collection and influences the strength of the inhibition of biofilm formation.

Caffeic Acid phenethyl ester is a potential therapeutic agent for oral cancer

Head and neck cancers, which affect 650,000 people and cause 350,000 deaths per year, is the sixth leading cancer by cancer incidence and eighth by cancer-related death worldwide. Oral cancer is the most common type of head and neck cancer. More than 90% of oral cancers are oral and oropharyngeal squamous cell carcinoma (OSCC). The overall five-year survival rate of OSCC patients is approximately 63%, which is due to the low response rate to current therapeutic drugs. In this review we discuss the possibility of using caffeic acid phenethyl ester (CAPE) as an alternative treatment for oral cancer. CAPE is a strong antioxidant extracted from honeybee hive propolis. Recent studies indicate that CAPE treatment can effectively suppress the proliferation, survival, and metastasis of oral cancer cells. CAPE treatment inhibits Akt signaling, cell cycle regulatory proteins, NF-κB function, as well as activity of matrix metalloproteinase (MMPs), epidermal growth factor receptor (EGFR), and Cyclooxygenase-2 (COX-2). Therefore, CAPE treatment induces cell cycle arrest and apoptosis in oral cancer cells. According to the evidence that aberrations in the EGFR/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling, NF-κB function, COX-2 activity, and MMPs activity are frequently found in oral cancers, and that the phosphorylation of Akt, EGFR, and COX-2 correlates to oral cancer patient survival and clinical progression, we believe that CAPE treatment will be useful for treatment of advanced oral cancer patients.

International Regulations of Propolis Quality: Required Assays do not Necessarily Reflect their Polyphenolic-Related In Vitro Activities

Propolis has been proposed as a polyphenolic-rich natural product potentially able to be used for human consumption or even for medicinal proposes. To guarantee a minimum phenolic and flavonoid content and as consequence of their related-biological activities, international requirements of propolis quality are commonly applied. In this work we assessed phenolic and flavonoid contents of propolis; the antioxidant capacity (toward peroxyl radicals and hypochlorous acid); the ability to generate nitric oxide (NO); and, finally the antimicrobial activity of 6 propolis samples from the VI region of Chile. Our results show that the total phenolic and flavonoid content of propolis samples are not always in agreement with their polyphenolic-associated in vitro activities. For example, P03 and P06 samples showed the lowest (25 ± 4 GAE/g propolis) and the highest (105 ± 3 GAE/g propolis) total phenolic content, respectively. This was in agreement with flavonoid content and their Oxygen Radical Absorbance Capacity (ORAC) activity. However, this dependence was not observed toward HOCl, NO release and antimicrobial activity. Based on our results, we consider that, in order to guarantee the antioxidant or antimicrobial in vitro effects, the international regulations of propolis quality should contemplate the convenience of incorporating other simple analytical test such as ORAC or antimicrobial tests.

The Natural Flavonoid Pinocembrin: Molecular Targets and Potential Therapeutic Applications

Pinocembrin is a natural flavonoid compound extracted from honey, propolis, ginger roots, wild marjoram, and other plants. In preclinical studies, it has shown anti-inflammatory and neuroprotective effects as well as the ability to reduce reactive oxygen species, protect the blood-brain barrier, modulate mitochondrial function, and regulate apoptosis. Considering these pharmaceutical characteristics, pinocembrin has potential as a drug to treat ischemic stroke and other clinical conditions. In this review, we summarize its pharmacologic characteristics and discuss its mechanisms of action and potential therapeutic applications.

Possible molecular targets for therapeutic applications of caffeic acid phenethyl ester in inflammation and cancer

Of the various derivatives of caffeic acid, caffeic acid phenethyl ester (CAPE) is a hydrophobic, bioactive polyphenolic ester obtained from propolis extract. The objective in writing this review article was to summarize all published studies on therapeutics of CAPE in inflammation and cancer to extract direction for future research. The possible molecular targets for the action of CAPE, include various transcription factors such as nuclear factor-κB, tissue necrosis factor-α, interleukin-6, cyclooxygenase-2, Nrf2, inducible nitric oxide synthase, nuclear factor of activated T cells, hypoxia-inducible factor-1α, and signal transducers and activators of transcription. Based on the valuable data on its therapeutics in inflammation and cancer, clinical studies of CAPE should also be conducted to explore its toxicities, if any.

Propolis in dentistry and oral cancer management

Propolis, known as bee glue, is a wax-cum-resin substance, which is created out of a mix of buds from some trees with the substance secreted from the bee's glands. Its diverse chemical content is responsible for many valuable properties. Multiple applications of propolis have been studied and described in detail for centuries. However, currently available information on propolis is scarce. A literature search in the PubMed database was performed for English language articles, using the search terms propolis, oral health, dentistry, and oral cancer; no restrictions were used for publication dates. The aim of the article was to review propolis and its applications in dentistry including oral cancer.