Composition and functional properties of propolis (bee glue): A review

Prenylated Trans-Cinnamic Esters and Ethers against Clinical Fusarium spp.: Repositioning of Natural Compounds in Antimicrobial Discovery

Onychomycosis is a common nail infection mainly caused by species belonging to the F. oxysporum, F. solani, and F. fujikuroi species complexes. The aim of this study was to evaluate the in vitro susceptibility of six representative strains of clinically relevant Fusarium spp. toward a set of natural-occurring hydroxycinnamic acids and their derivatives with the purpose to develop naturally occurring products in order to cope with emerging resistance phenomena. By introducing a prenylated chain at one of the hydroxy groups of trans-cinnamic acids 1–3, ten prenylated derivatives (coded 4–13) were preliminarily investigated in solid Fusarium minimal medium (FMM). Minimal inhibitory concentration (MIC) and lethal dose 50 (LD₅₀) values were then determined in liquid FMM for the most active selected antifungal p-coumaric acid 3,3′-dimethyl allyl ester 13, in comparison with the conventional fungicides terbinafine (TRB) and amphotericin B (AmB), through the quantification of the fungal growth. Significant growth inhibition was observed for prenylated derivatives 4–13, evidencing ester 13 as the most active. This compound presented MIC and LD₅₀ values (62–250 µM and 7.8–125 µM, respectively) comparable to those determined for TRB and AmB in the majority of the tested pathogenic strains. The position and size of the prenylated chain and the presence of a free phenol OH group appear crucial for the antifungal activity. This work represents the first report on the activity of prenylated cinnamic esters and ethers against clinical Fusarium spp. and opens new avenues in the development of alternative antifungal compounds based on a drug repositioning strategy.

The Potential of Honeybee Products for Biomaterial Applications

The development of biomaterials required continuous improvements in their properties for new tissue engineering applications. Implants based on biocompatible materials and biomaterial-based dressings are susceptible to infection threat; moreover, target tissues can suffer injuring inflammation. The inclusion of nature-derived bioactive compounds usually offers a suitable strategy to expand or increase the functional properties of biomaterial scaffolds and can even promote tissue healing. Honey is traditionally known for its healing property and is a mixture of phytochemicals that have a proven reputation as antimicrobial, anti-inflammatory, and antioxidant agents. This review discusses on the potential of honey and other honeybee products for biomaterial improvements. Our study illustrates the available and most recent literature reporting the use of these natural products combined with different polymeric scaffolds, to provide original insights in wound healing and other tissue regenerative approaches.

The Cardiovascular Therapeutic Potential of Propolis-A Comprehensive Review

Simple Summary

Propolis, also described as bee glue, is a natural component made up of a resinous mixture of honeybee compounds from multiple botanical sources. The literature has demonstrated a variety of medicinal properties attributed to propolis due to its chemical complexity. However, the positive effects of propolis on cardiovascular health have gained little coverage. Therefore, we aimed to provide an accurate and up-to-date review of the main cardiovascular health benefits of propolis. In particular, we intend to establish the key varieties of propolis and pharmacological compounds with the therapeutic effects that are most encouraging, as well as the physiological processes by which those advantages are accomplished. The Brazilian green and red varieties reveal the greatest number of beneficial activities among the varieties of propolis studied. While much of the cardiovascular beneficial effects appear to derive from the cumulative actions of several compounds working via multiple signaling mechanisms, some individual compounds that may enhance the existing therapeutic arsenal have also shown significant results. It is also worth exploring the prospect of using propolis as food supplements.

Abstract

Owing to its chemical richness, propolis has a myriad of therapeutic properties. To the authors’ knowledge, this is the first comprehensive review paper on propolis to focus exclusively on its major effects for cardiovascular health. The propolis compound varieties with the most promising therapeutic benefits and their respective physiological mechanisms will be discussed. Propolis displays an anti-atherosclerotic activity, attained through modulation of the plasma lipid profile and through stabilization of the fatty plaque by inhibiting macrophage apoptosis, vascular smooth muscle proliferation and metalloproteinase activity. The antihypertensive effects of propolis probably arise through the combination of several mechanisms, including the suppression of catecholamine synthesis, stimulation of endothelium-dependent vasorelaxation and vascular anti-inflammatory activity. The anti-hemostatic activity of propolis is attributed to the inhibition of platelet plug formation and antifibrinolytic activity. By inhibiting the secretion of proangiogenic factors, propolis suppresses endothelial cell migration and tubulogenesis, exerting antiangiogenic activity. The antioxidant and anti-inflammatory activities are responsible for protection against vascular endothelial and cardiomyocyte dysfunction, mostly by the prevention of oxidative stress. Among the reviewed propolis varieties, the Brazilian green and red varieties show the largest number of beneficial activities. Further research, especially preclinical, should be conducted to assess the cardiovascular benefits of the given varieties with different compositions.

Exogenous Application of Foliar Salicylic Acid and Propolis Enhances Antioxidant Defenses and Growth Parameters in Tomato Plants

Salicylic acid (SA) and propolis (PR) are known to regulate the physiological process and to have a relevant role in bioactive compounds content. Our experiment was designed to evaluate the effect of SA and PR application on the growth, yield, and quality parameters of tomato grown for the fresh market in field conditions in Egypt. We studied the effect of twelve treatments where SA (0.50, 1.00, 1.50, 2.00, and 2.50 mM) and PR (1, 2, 10, 20, and 100 mg propolis mL^-1) were applied at increasing doses as a sole agent or combined each other (1.50 mM + 10 mg mL^-1 for SA and PR, respectively). An untreated control was also considered. Tomato plants treated with SA (0.50, 1.00, and 1.50 mM) showed a significant effect in all traits especially SA1 (0.50 mM) in growth parameters and SA2 (1.00 mM) in pigment and antioxidant content. Propolis foliar application was more effective than SA as it revealed that raising the concentration of aqueous extract enhanced the growth parameters and pigment in tomato. The best result was obtained by the 10 mg mL^-1 treatment. The effect of propolis on antioxidant enzymes varied as the 10 mg mL^-1 treatment was effective on peroxidases and superoxide dismutase, while 100 mg mL^-1 was more effective on catalase. Salicylic acid and propolis have a positive effect on both preserving tomato plants and on nutrient supply, so the mixed intermediate concentration (1.50 mM + 10 mg mL^-1) is considered very effective and results in an improvement of all plant traits.

Plant Sources Responsible for the Chemical Composition and Main Bioactive Properties of Poplar-Type Propolis

Propolis is a resinous mixture, made by the honeybees from substances collected from tree or other plant buds, plant exudates, or resins found in the stem, branches, or leaves of different plants. The geographical origin of propolis is given by plant sources from respective areas. Different studies have classified this bee product according to the vegetal material from the same areas. Poplar-type propolis has the widest spread in the world, in the temperate zones from Europe, Asia, or North America. The name is given by the main plant source from where the bees are collecting the resins, although other vegetal sources are present in the mentioned areas. Different Pinus spp., Prunus spp., Acacia spp. and also Betula pendula, Aesculus hippocastanum, and Salix alba are important sources of resins for "poplar-type" propolis. The aim of this review is to identify the vegetal material's chemical composition and activities of plant resins and balms used by the bees to produce poplar-type propolis and to compare it with the final product from similar geographical regions. The relevance of this review is to find the similarities between the chemical composition and properties of plant sources and propolis. The latest determination methods of bioactive compounds from plants and propolis are also reviewed.

The Role of Mitochondria in Brain Cell Protection from Ischaemia by Differently Prepared Propolis Extracts

Mitochondria are both the primary targets and mediators of ischaemic damage in brain cells. Insufficient oxygen causes reactive oxygen species that damage the mitochondria, leading to the loss of functionality and viability of highly energy-demanding neurons. We have recently found that aqueous (AqEP), polyethylene glycol-aqueous (Pg-AqEP) and ethanolic propolis extracts (EEP) can modulate mitochondria and ROS production in C6 cells of astrocytic origin. The aim of this study was to investigate the effect of the extracts on viability, mitochondrial efficiency and superoxide generation, and inflammatory cytokine release in primary rat cerebellar neuronal-glial cell cultures affected by ischaemia (mimicked by hypoxia +/- deoxyglucose). AqEP and Pg-AqEP (15-60 µg/mL of phenolic compounds, or PC) significantly increased neuronal viability in ischaemia-treated cultures, and this was accompanied by a reduction in mitochondrial superoxide levels. Less extended protection against ischaemia-induced superoxide production and death was exhibited by 2 to 4 µg/mL of PC EEP. Both Pg-AqEP and Ag-EP (but not EEP) significantly protected the cultures from hypoxia-induced elevation of TNF-α, IL-1β and IL-6. Only Pg-AqEP (but not AqEP or EEP) prevented hypoxia-induced loss of the mitochondrial basal and ATP-coupled respiration rate, and significantly increased the mitochondrial respiratory capacity. Summarising, the study revealed that hydrophilic propolis extracts might protect brain cells against ischaemic injury by decreasing the level of mitochondrial superoxide and preventing inflammatory cytokines, and, in the case of Pg-AqEP, by protecting mitochondrial function.

Determination of Neonicotinoid Pesticides in Propolis with Liquid Chromatography Coupled to Tandem Mass Spectrometry

In this study, a method was developed for the determination of five neonicotinoid pesticides (acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam) in propolis. Two sample preparation methods were tested: solid-phase extraction and the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. The identities of analytes were confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the selected reaction monitoring mode. Solid-phase extraction resulted in cleaner extracts; therefore, the SPE-LC-MS/MS method was validated according to the SANTE protocol in triplicate at two spiking levels (10 ng/g and 50 ng/g). The average recoveries of analytes ranged from 61% to 101%, except for clothianidin (10-20%). The LOD ranged from 0.2 ng/g to 4.4 ng/g, whereas the LOQ was in the range of 0.8 ng/g-14.7 ng/g. In order to compensate for the matrix effect, matrix-matched calibration was used. Good accuracy (relative error: 1.9-10.4%) and good linearity (R² > 0.991) were obtained for all compounds. The optimised method was applied to 30 samples: 18 raw propolis and 12 ethanol tinctures. Acetamiprid, imidacloprid, and thiacloprid were detectable in seven samples but were still below the LOQ. This study is the first to report the determination of several neonicotinoid residues in propolis.

Mollicute Anti-Adhesive and Growth Inhibition Properties of the Methanolic Extract of Propolis from the Brazilian Native Bee Melipona quadrifasciata

Hydroalcoholic propolis extracts from the bee species Melipona quadrifasciata have been shown to possess antimicrobial activity against different mollicute strains, but a methanolic extract (ME) could contain an increased diversity of nonpolar bioactive components with a potentially higher antimicrobial activity. The ME obtained by maceration of the propolis sample was fractionated with solvents of different polarities and then, purified by silica gel column chromatography through biomonitoring of its antimicrobial activity against mollicute strains. Analysis by gas chromatography-mass spectrometry (GC/MS) enabled the identification of compounds using the NIST library. Minimum inhibitory concentrations (MICs) of the samples were determined by broth microdilution. Anti-adhesive assays were performed with Mycoplasma pneumoniae cells. The hexane (MIC=62.5 mg/L) and dichloromethane (MIC=125 mg/L) fractions presented the most promising results against M. pneumoniae. They were fractionated into 74 subfractions, and even the best ones did not show better results (MIC>250 mg/L) than their original fractions, likely due to the loss of terpene compounds that seem to act in synergy. The dichloromethane subfraction FD4 was highlighted in the anti-adhesive assay with an inhibitory activity of 21.6 %. A synergistic effect of the nonpolar compounds in M. quadrifasciata propolis may be responsible for its antibacterial activity, but several purified components can improve its anti-adhesive properties.

To bee or not to bee? The bee extract propolis as a bioactive compound in the burden of lifestyle diseases

Propolis is a polyphenolic plant resin collected by bees to protect hives against pathogens and temperature drop. It exhibits antibacterial, antioxidant, and antiinflammatory properties. Propolis has been reported to possess antidiabetic properties and display beneficial effects against cardiovascular disease, gut dysbiosis, and chronic kidney disease. It has an excellent clinical safety profile, with no known toxic effects described so far. In this review, we discuss the salutogenic effects of propolis, with particular reference to modulating notable features of chronic kidney disease, notably those involving cardiovascular risks.

Historical and modern research on propolis and its application in wound healing and other fields of medicine and contributions by Polish studies

ETHNOPHARMACOLOGICAL RELEVANCE

The history of medical application of propolis (also known as bee glue) dates back to the times of ancient Greeks, Romans, Persians and Egyptians. Honey and other bee products, including propolis, occupy an important place in Polish folk medicine. Scientific research on propolis in Poland began in the early 1960s in Zabrze and continues until now.

AIM OF THE REVIEW

The aim of this review is to provide an overview of information on Polish research on propolis and its medical application with particular emphasis on studies concerning wound healing. Consequently, our goal is also to shed a new light on therapeutic potential of Polish propolis in order to support future research in the field.

MATERIALS AND METHODS

A systematic review of scientific literature on propolis and its medical application was performed by using the literature databases (PubMed, Web of Science, Google Scholar). We paid special attention to papers describing the effect of propolis on skin wound healing as well as to Polish contribution to research on propolis.

RESULTS

Professor Stan Scheller was the first Polish scientist dealing with propolis and its medical potential. His legacy was continued by several research teams that studied the topic in various aspects. They analyzed propolis composition, its antioxidant, anti-inflammatory, antimicrobial, antiapoptotic and anticancer properties as well as its application in dentistry and wound treatment. Burn wound healing physiology after propolis administration was thoroughly studied on pig model, whereas research on patients proved the efficacy of propolis in chronic venous leg ulcer treatment.

CONCLUSION

Polish scientists have made a significant contribution to the research on propolis, its biological properties and influence on wound healing. Propolis ointments can effectively accelerate the healing process and improve healing physiology, so they can be recommended as a promising topical medication for wound treatment in the future clinical and preclinical trials.

The Strong Anti-Kinetoplastid Properties of Bee Propolis: Composition and Identification of the Active Agents and Their Biochemical Targets

The kinetoplastids are protozoa characterized by the presence of a distinctive organelle, called the kinetoplast, which contains a large amount of DNA (kinetoplast DNA (kDNA)) inside their single mitochondrion. Kinetoplastids of medical and veterinary importance include Trypanosoma spp. (the causative agents of human and animal African Trypanosomiasis and of Chagas disease) and Leishmania spp. (the causative agents of the various forms of leishmaniasis). These neglected diseases affect millions of people across the globe, but drug treatment is hampered by the challenges of toxicity and drug resistance, among others. Propolis (a natural product made by bees) and compounds isolated from it are now being investigated as novel treatments of kinetoplastid infections. The anti-kinetoplastid efficacy of propolis is probably a consequence of its reported activity against kinetoplastid parasites of bees. This article presents a review of the reported anti-kinetoplastid potential of propolis, highlighting its anti-kinetoplastid activity in vitro and in vivo regardless of geographical origin. The mode of action of propolis depends on the organism it is acting on and includes growth inhibition, immunomodulation, macrophage activation, perturbation of the cell membrane architecture, phospholipid disturbances, and mitochondrial targets. This gives ample scope for further investigations toward the rational development of sustainable anti-kinetoplastid drugs.

Efficacy and safety of propolis mouthwash in management of radiotherapy induced oral mucositis; A randomized, double blind clinical trial

AIM AND BACKGROUND

Propolis has been used for the management of oral mucositis in a number of studies. Due to lack of sufficient evidence especially in radiotherapy induced oral mucositis, the present study was designed to evaluate the efficacy and safety of propolis mouthwash in oral mucositis and dysphagia in patients undergoing head and neck radiotherapy.

MATERIALS AND METHODS

This study was a prospective, randomised, double-blind, placebo-controlled trial. The patients randomly divided into two groups receiving either the propolis or the placebo mouthwash. Patients were advised to rinse their mouth with 15 mL three times daily for four weeks. Severity of mucositis and dysphagia were evaluated by the National Cancer Institute Common Toxicity Criteria (NCI-CTC) and Common Terminology Criteria for Adverse Events (CTCAE), respectively.

RESULTS

Thirty patients completed the study. Each group consisted of 15 patients. Although, there is not any significant difference between two groups in the first week of radiotherapy, a significant difference was seen in the second, the third and the fourth week (p = 0.03, 0.02, 0.02, respectively). Dysphagia reported as a mild score in the propolis group only in the fourth week which is significant compared with the placebo group (p = 0.01). There is not any serious adverse effect related to propolis or placebo during the study.

CONCLUSION

It seems that propolis mouthwash is an effective and safe medication for alleviation of oral mucositis and dysphagia in patients under head and neck radiotherapy.

Apitherapy for Parkinson's Disease: A Focus on the Effects of Propolis and Royal Jelly

The vast increase of world's aging populations is associated with increased risk of age-related neurodegenerative diseases such as Parkinson's disease (PD). PD is a widespread disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra, which encompasses a wide range of debilitating motor, emotional, cognitive, and physical symptoms. PD threatens the quality of life of millions of patients and their families. Additionally, public welfare and healthcare systems are burdened with its high cost of care. Available treatments provide only a symptomatic relief and produce a trail of noxious side effects, which increase noncompliance. Hence, researchers have recently focused on the use of nutraceuticals as safe adjunctive treatments of PD to limit its progress and associated damages in affected groups. Propolis is a common product of the beehive, which possesses a large number of therapeutic properties. Royal jelly (RJ) is a bee product that is fed to bee queens during their entire life, and it contributes to their high physical fitness, fertility, and long lifespan. Evidence suggests that propolis and RJ can promote health by preventing the occurrence of age-related debilitating diseases. Therefore, they have been used to treat various serious disorders such as diabetes mellitus, cardiovascular diseases, and cancer. Some evolving studies used these bee products to treat PD in animal models. However, a clear understanding of the collective effect of propolis and RJ as well as their mechanism of action in PD is lacking. This review evaluates the available literature for the effects of propolis and RJ on PD. Whenever possible, it elaborates on the underlying mechanisms through which they function in this disorder and offers insights for fruitful use of bee products in future clinical trials.

Souto E, Cardoso JC. Red Propolis and Its Dyslipidemic Regulator Formononetin: Evaluation of Antioxidant Activity and Gastroprotective Effects in Rat Model of Gastric Ulcer

Propolis has various pharmacological properties of clinical interest, and is also considered a functional food. In particular, hydroalcoholic extracts of red propolis (HERP), together with its isoflavonoid formononetin, have recognized antioxidant and anti-inflammatory properties, with known added value against dyslipidemia. In this study, we report the gastroprotective effects of HERP (50–500 mg/kg, p.o.) and formononetin (10 mg/kg, p.o.) in ethanol and non-steroidal anti-inflammatory drug-induced models of rat ulcer. The volume, pH, and total acidity were the evaluated gastric secretion parameters using the pylorus ligature model, together with the assessment of gastric mucus contents. The anti-Helicobacter pylori activities of HERP were evaluated using the agar-well diffusion method. In our experiments, HERP (250 and 500 mg/kg) and formononetin (10 mg/kg) reduced (p < 0.001) total lesion areas in the ethanol-induced rat ulcer model, and reduced (p < 0.05) ulcer indices in the indomethacin-induced rat ulcer model. Administration of HERP and formononetin to pylorus ligature models significantly decreased (p < 0.01) gastric secretion volumes and increased (p < 0.05) mucus production. We have also shown the antioxidant and anti-Helicobacter pylori activities of HERP. The obtained results indicate that HERP and formononetin are gastroprotective in acute ulcer models, suggesting a prominent role of formononetin in the effects of HERP.

Apitherapy for Age-Related Skeletal Muscle Dysfunction (Sarcopenia): A Review on the Effects of Royal Jelly, Propolis, and Bee Pollen

The global pandemic of sarcopenia, skeletal muscle loss and weakness, which prevails in up to 50% of older adults is increasing worldwide due to the expansion of aging populations. It is now striking young and midlife adults as well because of sedentary lifestyle and increased intake of unhealthy food (e.g., western diet). The lockdown measures and economic turndown associated with the current outbreak of Coronavirus Disease 2019 (COVID-19) are likely to increase the prevalence of sarcopenia by promoting sedentarism and unhealthy patterns of eating. Sarcopenia has multiple detrimental effects including falls, hospitalization, disability, and institutionalization. Although a few pharmacological agents (e.g., bimagrumab, sarconeos, and exercise mimetics) are being explored in different stages of trials, not a single drug has been approved for sarcopenia treatment. Hence, research has focused on testing the effect of nutraceuticals, such as bee products, as safe treatments to prevent and/or treat sarcopenia. Royal jelly, propolis, and bee pollen are common bee products that are rich in highly potent antioxidants such as flavonoids, phenols, and amino acids. These products, in order, stimulate larval development into queen bees, promote defenses of the bee hive against microbial and environmental threats, and increase royal jelly production by nurse bees. Thanks to their versatile pharmacological activities (e.g., anti-aging, anti-inflammatory, anticarcinogenic, antimicrobial, etc.), these products have been used to treat multiple chronic conditions that predispose to muscle wasting such as hypertension, diabetes mellitus, cardiovascular disorder, and cancer, to name a few. They were also used in some evolving studies to treat sarcopenia in laboratory animals and, to a limited degree, in humans. However, a collective understanding of the effect and mechanism of action of these products in skeletal muscle is not well-developed. Therefore, this review examines the literature for possible effects of royal jelly, bee pollen, and propolis on skeletal muscle in aged experimental models, muscle cell cultures, and humans. Collectively, data from reviewed studies denote varying levels of positive effects of bee products on muscle mass, strength, and function. The likely underlying mechanisms include amelioration of inflammation and oxidative damages, promotion of metabolic regulation, enhancement of satellite stem cell responsiveness, improvement of muscular blood supply, inhibition of catabolic genes, and promotion of peripheral neuronal regeneration. This review offers suggestions for other mechanisms to be explored and provides guidance for future trials investigating the effects of bee products among people with sarcopenia.

Bee products as a source of promising therapeutic and chemoprophylaxis strategies against COVID-19 (SARS-CoV-2)

The emergence of novel coronavirus (SARS‐CoV‐2) in 2019 in China marked the third outbreak of a highly pathogenic coronavirus infecting humans. The novel coronavirus disease (COVID‐19) spread worldwide, becoming an emergency of major international concern. However, even after a decade of coronavirus research, there are still no licensed vaccines or therapeutic agents to treat the coronavirus infection. In this context, apitherapy presents as a promising source of pharmacological and nutraceutical agents for the treatment and/or prophylaxis of COVID‐19. For instance, several honeybee products, such as honey, pollen, propolis, royal jelly, beeswax, and bee venom, have shown potent antiviral activity against pathogens that cause severe respiratory syndromes, including those caused by human coronaviruses. In addition, the benefits of these natural products to the immune system are remarkable, and many of them are involved in the induction of antibody production, maturation of immune cells, and stimulation of the innate and adaptive immune responses. Thus, in the absence of specific antivirals against SARS‐CoV‐2, apitherapy could offer one hope toward mitigating some of the risks associated with COVID‐19.

Effect of the Solvent on Propolis Phenolic Profile and its Antifungal, Antioxidant, and In Vitro Cytoprotective Activity in Human Erythrocytes Under Oxidative Stress

Propolis is a natural bee product with various beneficial biological effects. The health-promoting properties of propolis depend on its chemical composition, particularly the presence of phenolic compounds. The aim of this study was to evaluate the relationship between extraction solvent (acetone 100%, ethanol 70% and 96%) and the antifungal, antioxidant, and cytoprotective activity of the extracts obtained from propolis. Concentrations of flavonoids and phenolic acids in the propolis extracts were determined using ultrahigh-performance liquid chromatography. The antioxidant potential of different extracts was assessed on the basis of 2,2-diphenyl-1-picrylhydrazyl (DPPH·) free-radical-scavenging activity, Fe³⁺-reducing power, and ferrous ion (Fe²⁺)-chelating activity assays. The ability of the extracts to protect human red blood cell membranes against free-radical-induced damage and their antifungal activity was also determined. The results showed that the concentration of flavonoids in the propolis extracts was dependent on the solvent used in the extraction process and pinocembrin, chrysin, galangin, and coumaric acid were the most abundant phenols. All extracts exhibited high antioxidant potential and significantly protected human erythrocytes against oxidative damage. On the other hand, the antifungal activity of the propolis extracts depended on the solvent used in extraction and the fungal strains tested. It needs to be stressed that, to the best of our knowledge, there is no study relating the effect of solvent used for extraction of Polish propolis to its phenolic profile, and its antifungal, antioxidant, and cytoprotective activity.

Antifibrotic effect of curcumin, N-acetyl cysteine and propolis extract against bisphenol A-induced hepatotoxicity in rats: Prophylaxis versus co-treatment

AIMS

Bisphenol A (BPA) has been shown to induce liver fibrosis in rodents. Therefore, this study examined the protective effect of a triple combination of curcumin (Cur), N-acetyl cysteine (NAC) and propolis (Prp) extract against BPA-induced hepatic fibrosis.

METHODS

100 Wistar male rats were equally assigned into 10 groups; one group was designated as control. 10 rats were gavaged with BPA (50 mg/kg/day) for 8 wk and left un-treated (BPA group). The remaining 80 rats were divided into 8 groups, distributed in 2 models. Protective model: rats were daily co-treated with BPA and Cur (100 mg/kg, p.o) or NAC (150 mg/kg, p.o) or Prp (200 mg/kg, p.o) or their combination for 8 wk. Preventive model: rats were daily treated with Cur or NAC or Prp or their combination for 4 wk before BPA administration and then in the same manner as protective model.

KEY FINDINGS

Current treatment interventions significantly alleviated BPA-induced hepatic damage and fibrosis. They also restored pro-oxidant/antioxidant balance, shifted cytokine balance towards the anti-inflammatory side, decreasing interleukin-1β/interleukin-10 ratio. Moreover, these compounds seem to exert anti-apoptotic effects by increasing the immunoexpression of B-cell lymphoma 2 in hepatocytes and decreasing hepatic caspase-3 content. Finally, they ameliorated extracellular matrix turn over through down-regulation of matrix metalloproteinase-9 and up-regulation of tissue inhibitor of matrix metalloproteinase-2 genetic expression.

SIGNIFICANCE

Current treatments guarded against BPA-induced hepatic fibrosis due to their antioxidant, anti-inflammatory and anti-apoptotic properties, decreasing extracellular matrix turnover. Interestingly, the triple therapy provided hepatoprotection superior to monotherapy. Besides, prophylactic and concurrent treatments seem to be more effective than concurrent treatments.

Biochemical Composition of Propolis and Its Efficacy in Maintaining Postharvest Storability of Fresh Fruits and Vegetables

Propolis, also called “bee-glue,” is a natural resinous substance produced by honeybees from plant exudates, beeswax, and bee secretions in order to defend the hives. It has numerous phenolic compounds with more than 250 identified chemical compounds in its composition, which are also known to significantly vary according to the plant sources and season. Moreover, it has a long history in the traditional and scientific medicine as having antibacterial, anticancer, anti-inflammatory, anti-infective, and wound healing effects since 300 BC. In addition to its nutritional and health-promoting effects, it has been reported to improve the postharvest storability of fresh fruits, vegetables, and processed food products. Herein, the biochemical composition and the efficacy of propolis in maintaining the postharvest storability of fresh food products were discussed to provide comprehensive guide to farmers and food processing and storage sectors and to scientists. This review paper also highlights the important points to which special attention should be given in further studies in order to be able to use propolis to develop biopreservatives industrially and for quality preservation during storage.

Chemical Profile and Antibacterial Activity of a Novel Spanish Propolis with New Polyphenols also Found in Olive Oil and High Amounts of Flavonoids

Propolis is a natural product obtained from hives. Its chemical composition varies depending on the flora of its surroundings, but nevertheless, common for all types of propolis, they all exhibit remarkable biological activities. The aim of this study was to investigate the chemical composition and antimicrobial activity of a novel Spanish Ethanolic Extract of Propolis (SEEP). It was found that this new SEEP contains high amounts of polyphenols (205 ± 34 mg GAE/g), with unusually more than half of this of the flavonoid class (127 ± 19 mg QE/g). Moreover, a detailed analysis of its chemical composition revealed the presence of olive oil compounds (Vanillic acid, 1-Acetoxypinoresinol, p-HPEA-EA and 3,4-DHPEA-EDA) never detected before in propolis samples. Additionally, relatively high amounts of ferulic acid and quercetin were distinguished, both known for their important therapeutic benefits. Regarding the antimicrobial properties of SEEP, the minimal inhibitory and bactericidal concentrations (MIC and MBC) against Staphylococcus epidermidis strains were found at the concentrations of 240 and 480 µg/mL, respectively. Importantly, subinhibitory concentrations were also found to significantly decrease bacterial growth. Therefore, the results presented here uncover a new type of propolis rich in flavonoids with promising potential uses in different areas of human health.

Back to the basics: Propolis and COVID-19

The epidemiological burden of COVID-19 is a healthcare challenge throughout the world, not only in terms of testing the limits of medical capacities, but also as an enigma considering preventive strategies and methods. The upper respiratory tract mucosa is the first line of defense, as a physical barrier, as well as through multiple innate and adaptive immune mechanisms which are crucial for efficient antiviral responses. Identifying methods able to reduce or prevent colonization, viral adhesion, and promote virus shedding on mucous membranes or have the ability to inactivate pathogens and thus reduce virus dose and/or increase immune response would be essential in the management of COVID-19 outbreak and help in flattening the curve. We review the effects of propolis, an old remedy with proven antiviral properties, as a possible low-cost inhibitor of SARS-CoV-2 in the oropharyngeal niche, prophylaxis, or adjuvant therapy.

Chemopreventive and Chemotherapeutic Effect of Propolis and Its Constituents: A Mini-review

Propolis is a bee wax rich in various phytocomponents and traditionally used to treat various ailments. Propolis is reported to possess an array of biological properties including anti-inflammatory, antioxidant, anti-cancer, and anti-diabetic as well as cardioprotective, hepatoprotective, renoprotective, and derma protective activities. A plethora of studies confirmed that propolis is effective against various types of cancer including head and neck, lung, liver, brain (glioma), pancreas, kidney, prostate, skin (melanoma), breast, oral, esophagus, gastric, colorectal, and bladder cancers. However, many researchers have demonstrated that propolis displays potent chemoprotective/chemopreventive or anti-cancer activity against only a few types of cancers like oral, gastrointestinal, dermal (melanoma), breast, and prostate cancers. Therefore, this mini-review only summarizes the chemopreventive/chemotherapeutic activities of propolis and its updated underlying mechanisms. Taken together, propolis displays potent chemoprotective or anti-cancer effect due to the presence of various phytocomponents which contribute to pro-apoptotic, cytotoxic, anti-proliferative (cell cycle arrest), anti-metastatic, anti-invasive, anti-angiogenic and anti-genotoxic or anti-mutagenic properties along with antioxidant, immunomodulatory, and anti-inflammatory functions. Hence, propolis could be used as an adjuvant for treating various cancers along with standard chemotherapeutic drugs. However, many large-scale clinical studies are needed to justify such applications.

Polish Propolis-Chemical Composition and Biological Effects in Tongue Cancer Cells and Macrophages

The purpose of this study was to compare the chemical composition and biological properties of Polish propolis. Ethanol, ethanol-hexane, hexane and hexane-ethanol extracts of propolis from three different regions of Poland were prepared. On the basis of the evaluation of their chemical composition as well as the extraction yield and free radical scavenging activity, the ethanol and hexane-ethanol extractions were proposed as the most effective methods. Subsequently, the biological properties of the extracts were evaluated to investigate the selectivity of an anticancer effect on tongue cancer cells in comparison to normal gingival fibroblasts. The obtained products demonstrated anticancer activity against tongue cancer cells. Additionally, when the lowest extract concentration (100 µg/mL) was applied, they were not cytotoxic to gingival fibroblasts. Finally, a possible anti-inflammatory potential of the prepared products was revealed, as reduced mitochondrial activity and proliferation of macrophages exposed to the extracts were observed. The results obtained indicate a potential of Polish propolis as a natural product with cancer-selective toxicity and anti-inflammatory effect. However, further studies are still needed to thoroughly explain the molecular mechanisms of its action and to obtain the promising health benefits of this versatile natural product.

Effects of Solvent and pH on Stingless Bee Propolis in Ultrasound-Assisted Extraction

Ultrasound-assisted extraction was used to extract propolis from a dark and resinous substance harvested from a beehive of Heterotrigona itama, which is commonly known as stingless bees. The propolis extracts were prepared using ethanol and water at different pH values of 3, 6, and 9. The yield of the ethanolic extract was significantly higher than the water extract, but there were no significant differences at different pH values. The ethanolic extract was found to have a lower 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than the water extract at pH values of 6 and 9. However, the acidic propolis extracts, particularly the ethanolic extract, were found to have the highest antioxidant capacity. The addition of 20% polyethylene glycol 400 in the solvent systems was unlikely to improve propolis extraction. This can be seen from the antioxidant capacity and metabolite profile of the propolis extracts. Gas chromatography–mass spectrometry (GC–MS)-based high throughput screening of the propolis extracts showed them to have small metabolites of hydrocarbons, esters, terpenes, and alkaloids, as well as high antioxidative 2,4-di-tert-butylphenol. The detection of mangostin, mangiferin, and a few flavanones in the acidic ethanolic extract by liquid chromatography tandem mass spectrometry LC–MS/MS proved its high antioxidant capacity compared to the water extract.

Antifungal and Antibacterial Effect of Propolis: A Comparative Hit for Food-Borne Pseudomonas, Enterobacteriaceae and Fungi

Propolis is a natural brownish resinous substance collected by honeybees (Apis mellifera), with a documented bioactivity against many microorganisms. In this study, the activity of propolis was investigated using some strains of Pseudomonas spp., Enterobacteriaceae, Lactobacillus plantarum, yeasts (Saccharomyces cerevisiae and Debaryomyces hansenii) and Fusarium oxysporum. Two approaches were used (a modified microdilution protocol and viable count), and the microorganisms were inoculated at two levels (low or high inoculum). The antimicrobial effect of propolis relies upon several factors, like the kind of microorganisms (for example S. cerevisiae was more resistant than D. hansenii, while Lactobacillus plantarum was never affected), the cell concentration (at high inoculum higher amounts of propolis were required for an antimicrobial action), and the mode of action (a delay of growth rather than a complete inhibition). The results of this paper point out, for the first time, the antimicrobial activity of propolis against some spoilers, with a focus on the possible effect; thus, they could be the background to designing an effective tool to prolong the shelf life of foods.

Effects of Propolis and Phenolic Acids on Triple-Negative Breast Cancer Cell Lines: Potential Involvement of Epigenetic Mechanisms

Triple-negative breast cancer is an aggressive disease frequently associated with resistance to chemotherapy. Evidence supports that small molecules showing DNA methyltransferase inhibitory activity (DNMTi) are important to sensitize cancer cells to cytotoxic agents, in part, by reverting the acquired epigenetic changes associated with the resistance to therapy. The present study aimed to evaluate if chemical compounds derived from propolis could act as epigenetic drugs (epi-drugs). We selected three phenolic acids (caffeic, dihydrocinnamic, and p-coumaric) commonly detected in propolis and the (−)-epigallocatechin-3-gallate (EGCG) from green tea, which is a well-known DNA demethylating agent, for further analysis. The treatment with p-coumaric acid and EGCG significantly reduced the cell viability of four triple-negative breast cancer cell lines (BT-20, BT-549, MDA-MB-231, and MDA-MB-436). Computational predictions by molecular docking indicated that both chemicals could interact with the MTAse domain of the human DNMT1 and directly compete with its intrinsic inhibitor S-Adenosyl-l-homocysteine (SAH). Although the ethanolic extract of propolis (EEP) did not change the global DNA methylation content, by using MS-PCR (Methylation-Specific Polymerase Chain Reaction) we demonstrated that EEP and EGCG were able to partly demethylate the promoter region of RASSF1A in BT-549 cells. Also, in vitro treatment with EEP altered the RASSF1 protein expression levels. Our data indicated that some chemical compound present in the EEP has DNMTi activity and can revert the epigenetic silencing of the tumor suppressor RASSF1A. These findings suggest that propolis are a promising source for epi-drugs discovery.

Evaluation of the In Vitro Wound-Healing Activity and Phytochemical Characterization of Propolis and Honey

Honey and propolis are natural substances produced by Apis mellifera that contain flavonoids, phenolic acids, and several other phytochemicals. The aim of this study was to phytochemically characterize three different types of honey and propolis, both separately and mixed, and to evaluate their wound-healing activity. Total phenolic compounds and flavonoids were determined using the Folin–Ciocalteu’s and aluminum chloride colorimetric methods, respectively. The antioxidant activity was evaluated by both the DPPH free radical scavenging assay and β-carotene bleaching test, and the anti-inflammatory activity was determined by a protein denaturation method. To evaluate the wound-healing activity of the samples, NHDF cells were subjected to a wound scratch assay. The obtained results showed that dark-brown honey presents a higher concentration of phenolic compounds and flavonoids, as well as higher antioxidant and anti-inflammatory activities. Propolis samples had the highest concentrations in bioactive compounds. Examining the microscopic images, it was possible to verify that the samples promote cell migration, demonstrating the wound-healing potential of honey and propolis.

Natural Products and Their Bioactive Compounds: Neuroprotective Potentials against Neurodegenerative Diseases

In recent years, natural products, which originate from plants, animals, and fungi, together with their bioactive compounds have been intensively explored and studied for their therapeutic potentials for various diseases such as cardiovascular, diabetes, hypertension, reproductive, cancer, and neurodegenerative diseases. Neurodegenerative diseases, including Alzheimer's disease, Huntington's disease, Parkinson's disease, and amyotrophic lateral sclerosis are characterized by the progressive dysfunction and loss of neuronal structure and function that resulted in the neuronal cell death. Since the multifactorial pathological mechanisms are associated with neurodegeneration, targeting multiple mechanisms of actions and neuroprotection approach, which involves preventing cell death and restoring the function to damaged neurons, could be promising strategies for the prevention and therapeutic of neurodegenerative diseases. Natural products have emerged as potential neuroprotective agents for the treatment of neurodegenerative diseases. This review focused on the therapeutic potential of natural products and their bioactive compounds to exert a neuroprotective effect on the pathologies of neurodegenerative diseases.

Biological control of yeast contamination of industrial foods by propolis

Bee glue (Propolis, PR), mixture of beeswax and resin is collected from honeybee (Apis mellifera) of different plant parts. The antimicrobial potential of PR against food borne yeast was reported. The experiment was designed to examine the way of antimicrobial impact of PR on food borne yeasts (Cryptococcus laurentii and Candida famata) and its usage use as biological strategy for the preservation of soft foods against microbial spoilage. The study also highlights, the ability of ethanol and water- PR extracts, discouraged growth of tested yeast. Antifungal properties were also determined using electron microscope while biochemical analysis was determined using free and proteinic amino acid technique and oxidative enzymes were determined using HPLC analysis. Antioxidant enzymes were determined using ELISA assay. The highest effect was recorded on C. laurentii however, the lowest effect shows on C. famata. The electron microscopic studies clearly disclosed the effect of water PR distillate on the external shape and internal organs of some tested yeast e.g. C. laurentii and C. famata. The result indicated some differences on concentrations of bio-chemical analyses for these tested yeasts treated with 70% water- PR extracts of different food materials. Moreover, biochemical analysis results also reported that the treated yeast indicated natural preservative to food products and considered as best alternative to the (chemical) preservatives currently employed.

Effect of Nanostructured Chitosan/Propolis Coatings on the Quality and Antioxidant Capacity of Strawberries During Storage

Strawberries have a thin epidermis and a high respiration rate. The use of edible coatings containing chitosan nanoparticles (CSNPs) and propolis (P) has been effective in preserving the shelf life and antioxidant capacity of various fruit and vegetable products. The present research evaluated the effect of coatings with CSNPs and P on the quality, antioxidant compounds, and antioxidant capacity of strawberries. The specific coatings that were evaluated were chitosan (CS), CS+CSNPs33%, CS + CSNPs + P10%, CS + CSNPs + P20%, CS + CSNPs + P30%, and a control with no coating. The variables were weight loss, firmness, total soluble solids (TSS), color, phenols, total flavonoids, antioxidant capacity, and sensory characteristics. An ANOVA and a Tukey test (p ≤ 0.05) were used to analyze the data. Strawberries covered with CS + CSNPs + P10% showed the lowest weight loss (9.77%), while those covered with CS + CSNPs + P20% had the greatest firmness (4.96 N). CS + CSNPs + P coatings at 10%, 20%, and 30% concentrations maintained the antioxidant compounds and antioxidant capacity in the evaluated fruit (28.49 mg GAE g−1, 554.61 μg quercetin g−1, and 92.48% DPPH, respectively). The application of nanostructured coatings did not modify the sensory characteristics of the fruit. Coatings with CSNPs and/or P could therefore be a viable alternative for preserving the quality and antioxidant capacity of strawberries.

A comparative study between Chinese propolis and Brazilian green propolis: metabolite profile and bioactivity

A comparative study between Chinese propolis and Brazilian green propolis showed that they have a distinct chemome but similar antioxidant and anti-inflammatory potential.

Methacrylate: An alternative fixing agent for identifying the botanical origin of propolis

PREMISE

A new technique was developed to identify the botanical origin of propolis, a resin-like material made by bees by mixing saliva and beeswax with plant buds and exudates, using methacrylate for permanent slide preparation.

METHODS AND RESULTS

Propolis samples were fixed in methacrylate to produce permanent slides. The anatomical structures of the plant fragments in the methacrylated propolis were compared with propolis slides prepared using conventional techniques that consist of propolis sediment obtained during a series of solvent reactions, filtration, and centrifugations, which cost a similar amount to produce. The techniques resulted in qualitative differences between the slides obtained. The methacrylated propolis sections allowed the detailed observation and identification of plant anatomical structures that were obscured in samples prepared using the conventional procedure. This clarity enabled the detailed evaluation of valuable taxon-diagnostic characters in a permanent slide, which can also be used for histochemical tests.

CONCLUSIONS

The methacrylated embedding of propolis is an affordable technique that could be implemented as a routine laboratory procedure. This new technique enables the efficient determination of the botanical origin of propolis.

Evidence on the Health Benefits of Supplemental Propolis

Propolis is a honey-related product with reported health benefits such as improved immunity, lowered blood pressure, treated allergies and skin conditions. A literature review and narrative synthesis were conducted to investigate the evidence on the reported health benefits and future direction of propolis products. Using a predefined search strategy we searched Medline (OvidSP), Embase and Central for quantitative and qualitative studies (1990-2018). Citation, reference, hand searches and expert consultation were also undertaken. Studies of randomised control trials and observational data on humans with health-related outcomes were included. Collected data were entered into NVivo software (Version 12, QRS International) and analysed using a thematic framework and a narrative synthesis of emergent themes. A total of 63 publications were discussed. The majority were cell-based and animal studies, with a few key human trials conducted. There is significant promise for propolis as an effective antioxidant and anti-inflammatory agent with particular promise in cardiometabolic health.

Biogenic synthesis of silver nanoparticles using Brazilian propolis

Biological methods have been used to synthesize silver nanoparticles through materials such as bacteria, fungi, plants, and propolis due to their reducing properties, stabilizer role and environmentally friendly characteristic. Considering the antimicrobial activity of propolis as well as the broad-spectrum antibacterial effects of silver nanoparticles, this study aim to describe the use of Brazilian propolis to synthesize silver nanoparticles (AgNP-P) and investigate its antimicrobial activity. The synthesis was optimized by factorial design, choosing the best conditions for smaller size particles. AgNP-P demonstrated a maximum absorbance at 412 nm in ultraviolet-visible spectra, which indicated a spherical format and its formation. Dynamic light scattering demonstrated a hydrodynamic size of 109 nm and polydispersity index less than 0.3, showing a good size distribution and stability. After its purification via centrifugation, microscopy analysis corroborates the format and showed the presence of propolis around silver nanoparticle. X-ray diffraction peaks were attributed to the main planes of the metallic silver crystalline structure; meanwhile infrared spectroscopy demonstrated the main groups responsible for silver reduction, represented by ∼22% of AgNP-P indicates by thermal analysis. Our product revealed an important antimicrobial activity indicating a synergism between propolis and silver nanoparticles as expected and promising to be an effective antimicrobial product to be used in infections.