Beyond the Biological Effect of a Chemically Characterized Poplar Propolis: Antibacterial and Antiviral Activity and Comparison with Flurbiprofen in Cytokines Release by LPS-Stimulated Human Mononuclear Cells

Chemical Markers in Italian Propolis: Chrysin, Galangin and CAPE as Indicators of Geographic Origin

Knowledge of the chemical composition of propolis is crucial for understanding the characteristics of products of different origins, but also for quality control and regulatory purposes. To date, official monographs or official analyses that allow researchers to evaluate propolis in a proper way have not yet been released. This study focuses on the characterization of twenty-seven Italian propolis samples and the identification of chemical markers that define its geographical provenance. Total polyphenol (TP) and total flavonoid (TF) content, alongside the quantification of pinocembrin, chrysin, galangin, and caffeic acid phenethyl ester (CAPE), were identified as potential markers. Additionally, DPPH assays were conducted to evaluate the antiradical activity of propolis samples. Our findings demonstrated that TPs, TFs and pinocembrin differed in propolis of different origins, especially in samples from the islands. However, the quantification of the sum of chrysin and galangin and CAPE provided a clearer distinction of the geographical origin of the propolis samples. In contrast, the DPPH assay did not prove useful for this purpose, as most results were similar and, therefore, not significant. This study lays the groundwork for future research on propolis. These findings could contribute to the development of more refined methods for distinguishing propolis origins, enhancing the understanding, valuation and quality control of this natural product in various applications.

Hive Products: Composition, Pharmacological Properties, and Therapeutic Applications

Beekeeping provides products with nutraceutical and pharmaceutical characteristics. These products are characterized by abundance of bioactive compounds. For different reasons, honey, royal jelly, propolis, venom, and pollen are beneficial to humans and animals and could be used as therapeutics. The pharmacological action of these products is related to many of their constituents. The main bioactive components of honey include oligosaccharides, methylglyoxal, royal jelly proteins (MRJPs), and phenolics compounds. Royal jelly contains jelleins, royalisin peptides, MRJPs, and derivatives of hydroxy-decenoic acid, particularly 10-hydroxy-2-decenoic acid (10-HDA), which possess antibacterial, anti-inflammatory, immunomodulatory, neuromodulatory, metabolic syndrome-preventing, and anti-aging properties. Propolis has a plethora of activities that are referable to compounds such as caffeic acid phenethyl ester. Peptides found in bee venom include phospholipase A2, apamin, and melittin. In addition to being vitamin-rich, bee pollen also includes unsaturated fatty acids, sterols, and phenolics compounds that express antiatherosclerotic, antidiabetic, and anti-inflammatory properties. Therefore, the constituents of hive products are particular and different. All of these constituents have been investigated for their properties in numerous research studies. This review aims to provide a thorough screening of the bioactive chemicals found in honeybee products and their beneficial biological effects. The manuscript may provide impetus to the branch of unconventional medicine that goes by the name of apitherapy.

Ethanolic Extract of Propolis and CAPE as Cardioprotective Agents against LPS and IFN-α Stressed Cardiovascular Injury

The inflammatory process is triggered by several factors such as toxins, pathogens, and damaged cells, promoting inflammation in various systems, including the cardiovascular system, leading to heart failure. The link between periodontitis as a chronic inflammatory disease and cardiovascular disease is confirmed. Propolis and its major component, caffeic acid phenethyl ester (CAPE), exhibit protective mechanisms and anti-inflammatory effects on the cardiovascular system. The objective of the conducted study was to assess the anti-inflammatory effects of the Polish ethanolic extract of propolis (EEP) and its major component-CAPE-in interferon-alpha (IFN-α), lipopolysaccharide (LPS), LPS + IFN-α-induced human gingival fibroblasts (HGF-1). EEP and CAPE were used at 10-100 µg/mL. A multiplex assay was used for interleukin and adhesive molecule detection. Our results demonstrate that EEP, at a concentration of 25 µg/mL, decreases pro-inflammatory cytokine IL-6 in LPS-induced HGF-1. At the same concentration, EEP increases the level of anti-inflammatory cytokine IL-10 in LPS + IFN-α-induced HGF-1. In the case of CAPE, IL-6 in LPS and LPS + IFN-α induced HGF-1 was decreased in all concentrations. However, in the case of IL-10, CAPE causes the highest increase at 50 µg/mL in IFN-α induced HGF-1. Regarding the impact of EEP on adhesion molecules, there was a noticeable reduction of E-selectin by EEP at 25, 50, and100 µg/mL in IFN-α -induced HGF-1. In a range of 10-100 µg/mL, EEP decreased endothelin-1 (ET-1) during all stimulations. CAPE statistically significantly decreases the level of ET-1 at 25-100 µg/mL in IFN-α and LPS + IFN-α. In the case of intercellular adhesion molecule-1 (ICAM-1), EEP and CAPE downregulated its expression in a non-statistically significant manner. Based on the obtained results, EEP and CAPE may generate beneficial cardiovascular effects by influencing selected factors. EEP and CAPE exert an impact on cytokines in a dose-dependent manner.

Investigation on the Efficacy of Two Food Supplements Containing a Fixed Combination of Selected Probiotics and β-Glucans or Elderberry Extract for the Immune System: Modulation on Cytokines Expression in Human THP-1 and PBMC

Several herbal and other natural products are used as ingredients in food supplements to strengthen immunity even if, very often, marketed products are proposed without a clear rationale or experimental evidence. In this study, we aimed to investigate the effect on human monocytes (THP-1) and on ex vivo human peripheral blood mononuclear cells (PBMC) of two formulations, one containing Bifidobacterium animalis subsp. lactis Bl-04® with β-glucans (for adults) and one containing Lactobacillus rhamnosus CRL1505 with elderberry extract (for children). We compared formulations with single ingredients, with bacterial lipopolysaccharide (LPS) and the drug pidotimod; cytokines expression level was evaluated testing different concentrations of samples at two exposure times. As expected, LPS caused a non-specific huge upregulation of cytokines expression both in THP-1 and in PBMC, whereas pidotimod mainly upregulated IL-2 in PBMC and IL-8 in THP-1. The two formulations showed a difference between a pro-inflammatory stimulus such as LPS, and also from an immunostimulant drug, such as pidotimod, as they mainly upregulated the expression of IL-6 and IL-10 in PBMC but not in THP-1, in a concentration-dependent mode. Probiotics were shown to play a major role, but β-glucans and elderberry extract exerted a synergistic activity. This work demonstrated that combining selected probiotics with other natural products having immunomodulatory properties is an interesting strategy to develop innovative formulations in the sector of food supplements.

Effect of in vitro simulated digestion on the anti-Helicobacter Pylori activity of different Propolis extracts

Helicobacter pylori (HP) is among the most common pathogens causing infection in humans worldwide. Oxidative stress and gastric inflammation are involved in the progression of HP-related gastric diseases, and they can be targeted by integrating conventional antibiotic treatment with polyphenol-enriched natural products. In this work, we characterised three different propolis extracts and evaluated their stability under in vitro simulated gastric digestion, compared to their main constituents alone. The extract with the highest stability to digestion (namely, the dark propolis extract, DPE) showed a minimum bactericidal concentration (MBC) lower than 1 mg/mL on HP strains with different virulence factors. Finally, since urease is one of the virulence factors contributing to the establishment of a microenvironment that promotes HP infection, we evaluated the possible inhibition of this enzyme by using molecular docking simulations and in vitro colorimetric assay, showing that galangin and pinocembrin may be involved in this activity.

In vitro antiviral effect of Mexican and Brazilian propolis and phenolic compounds against human coronavirus 229E

Propolis is a resinous substance collected by bees (Apis mellifera). It is used for its biological properties. This natural product is available as a safe therapeutic option. Herein, we report the antiviral effects of brown propolis extract from Mexico and green and red propolis extracts from Brazil, as well as their phenolic compounds (quercetin, caffeic acid, and rutin) in preventing infection of MRC-5 cells by HCoV-229E. Normal human fibroblast lung cells (MRC-5) were used to determine the cytotoxicity of the compounds. All samples studied showed antiviral activity. Green and brown propolis extracts, and quercetin exhibited the best EC50 values with values of 19.080, 11.240, and 77.208 µg/mL against HCoV-229E, respectively, and with TC50 of 62.19, 29.192, and 298 µg/mL on MRC-5 cells, respectively. These results are the first in vitro study of the effects of propolis on HCoV-229E and provide the basis for the development of natural formulations against other coronavirus strains.

Advances in the phytochemical screening and biological potential of propolis

Propolis is a natural resinous product collected from different parts of plants by bees and mixed with their salivary secretions. The occurrence of more than 180 different chemotypes has flavonoids, phenolic acids, esters, and phenolic aldehydes, as well as balsamic resins, beeswax, pollen, and essential and aromatic oils, among others. Its biological potential documented throughout the world justifies the need, from time to time, to organize reviews on the subject, with the intention of gathering and informing about the update on propolis. In this review (CRD42020212971), phytochemical advances, in vitro, in vivo, and clinical biological assays of pharmacological interest are showcased. The focus of this work is to present propolis clinical safety assays, antitumor, analgesic, antioxidant, anti-inflammatory, and antimicrobial activities. This literature review highlights propolis' promising biological activity, as it also suggests that studies associating propolis with nanotechnology should be further explored for enhanced bioprocessing applications.

Comparative evaluation of mouthwashes containing propolis and chlorhexidine for controlling inflammation resulting from plaque accumulation in patients with chronic gingivitis

Background

Limited data are available on the effect of mouthwashes containing Iranian propolis on plaque index (PI) and gingival index (GI) in patients with chronic gingivitis. The present study compared the effects of propolis and chlorhexidine (CHX) mouthwashes in patients with chronic gingivitis due to plaque accumulation.

Methods

In the present interventional study, 28 patients 18‒50 years of age with generalized chronic gingivitis were assigned to two groups (n=14). Periodontal parameters, including PI and GI, were determined in all the subjects at baseline. Groups A and B received CHX and propolis mouthwashes, respectively. All the subjects used the mouthwashes for two weeks. Then all the parameters were evaluated gain. Independent t-test was used to compare the periodontal parameters between the two groups. Paired t-test was used for intra-group comparisons. Statistical significance was defined at P<0.05.

Results

Two weeks after using the mouthwashes, the mean PI in the CHX group (21.71±1.63) was significantly lower than that in the propolis group (33.91±5.96). However, the mean PI and GI in the propolis group decreased significantly compared to the baseline (P=0.00).

Conclusion

Propolis significantly decreased the mean plaque and gingival inflammation in patients with chronic gingivitis. Although the reduction in PI in the propolis group was a little less than in the CHX group, the efficacy of propolis in reducing GI was comparable to CHX.

The Effects of Propolis on Viral Respiratory Diseases

Propolis remains an interesting source of natural chemical compounds that show, among others, antibacterial, antifungal, antiviral, antioxidative and anti-inflammatory activities. Due to the growing incidence of respiratory tract infections caused by various pathogenic viruses, complementary methods of prevention and therapy supporting pharmacotherapy are constantly being sought out. The properties of propolis may be important in the prevention and treatment of respiratory tract diseases caused by viruses such as severe acute respiratory syndrome coronavirus 2, influenza viruses, the parainfluenza virus and rhinoviruses. One of the main challenges in recent years has been severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing COVID-19. Recently, an increasing number of studies are focusing on the activity of various propolis preparations against SARS-CoV-2 as an adjuvant treatment for this infection. Propolis has shown a few key mechanisms of anti-SARS-CoV-2 action such as: the inhibition of the interaction of the S1 spike protein and ACE-2 protein; decreasing the replication of viruses by diminishing the synthesis of RNA transcripts in cells; decreasing the particles of coronaviruses. The anti-viral effect is observed not only with extracts but also with the single biologically active compounds found in propolis (e.g., apigenin, caffeic acid, chrysin, kaempferol, quercetin). Moreover, propolis is effective in the treatment of hyperglycemia, which increases the risk of SARS-CoV-2 infections. The aim of the literature review was to summarize recent studies from the PubMed database evaluating the antiviral activity of propolis extracts in terms of prevention and the therapy of respiratory tract diseases (in vitro, in vivo, clinical trials). Based upon this review, it was found that in recent years studies have focused mainly on the assessment of the effectiveness of propolis and its chemical components against COVID-19. Propolis exerts wide-spectrum antimicrobial activities; thus, propolis extracts can be an effective option in the prevention and treatment of co-infections associated with diseases of the respiratory tract.

Evaluation of Chemical Composition, Sun Protection Factor and Antioxidant Activity of Lithuanian Propolis and Its Plant Precursors

The growing interest in polyphenols of natural origin and their plant sources encourages the study of their chemical composition and biological activity. Propolis is widely used as a source of phenolic compounds. The aim of this study is to evaluate and compare the chemical composition, antioxidant activity and sun protection factor (SPF) of the ethanolic extracts of the poplar buds, birch buds and pine buds of propolis plant precursors collected in Lithuania. The IC50 concentration of the extracts was evaluated using DPPH and ABTS methods. Extracts of poplar buds, birch buds and propolis showed a lower IC50 concentration by ABTS and DPPH methods compared with pine buds extracts. Poplar buds and propolis extracts showed the highest SPF value, while birch and pine buds extracts showed a lower SPF value. High-performance liquid chromatography (HPLC) analysis results showed that phenolic acids, such as p-coumaric acid and cinnamic acid, and flavonoids, such as pinobanksin and pinocembrin, were identified in all the tested extracts. Salicin has been identified only in poplar buds extracts. The results of antioxidant activity showed that propolis poplar and birch buds are a promising source of biologically active polyphenols.

Recent Update on the Anti-Inflammatory Activities of Propolis

In recent years, research has demonstrated the efficacy propolis as a potential raw material for pharmaceuticals and nutraceuticals. There is limited report detailing the mechanisms of action of propolis and its bioactive compounds in relation to their anti-inflammatory properties. Thus, the aim of the present review is to examine the latest experimental evidence (2017-2022) regarding the anti-inflammatory properties of propolis. A systematic scoping review methodology was implemented. After applying the exclusion criteria, a total of 166 research publications were identified and retrieved from Scopus, Web of Science, and Pubmed. Several key themes related to the anti-inflammatory properties of propolis were subsequently identified, namely in relation to cancers, oral health, metabolic syndrome, organ toxicity and inflammation, immune system, wound healing, and pathogenic infections. Based on the latest experimental evidence, propolis is demonstrated to possess various mechanisms of action in modulating inflammation towards the regulatory balance and anti-inflammatory environment. In general, we summarize that propolis acts as an anti-inflammatory substance by inhibiting and downregulating TLR4, MyD88, IRAK4, TRIF, NLRP inflammasomes, NF-κB, and their associated pro-inflammatory cytokines such as IL-1β, IL-6, IFN-γ, and TNF-α. Propolis also reduces the migration of immune cells such as macrophages and neutrophils, possibly by downregulating the chemokines CXCL9 and CXCL10.

Development of propolis and essential oils containing oral/throat spray formulation against SARS-CoV-2 infection

A broad range of evidence has confirmed that natural products and essential oils might have the potential to suppress COVID-19 infection. Therefore, this study aimed to develop an oral/throat spray formulation for prophylactic use in the oral cavity or help treatment modalities. Based on a reference survey, several essential oils, a cold-pressed oil, and propolis were selected, and cytotoxicity and antiviral activity of each component and the developed spray formulation were examined against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection using Vero E6 cells. Anti-inflammatory, antimicrobial, and analgesic activities as well as mutagenicity and anti-mutagenicity of the formulation were analysed. Forty-three phenolics were identified in both propolis extract and oral/throat spray. The spray with 1:640-fold dilution provided the highest efficacy and the cytopathic effect was delayed for 54 h at this dilution, and the antiviral activity rate was 85.3%. A combination of natural products with essential oils at the right concentrations can be used as a supplement for the prevention of SARS-CoV-2 infection.

Perspectives for Uses of Propolis in Therapy against Infectious Diseases

Propolis has gained wide popularity over the last decades in several parts of the world. In parallel, the literature about propolis composition and biological properties increased markedly. A great number of papers have demonstrated that propolis from different parts of the world is composed mainly of phenolic substances, frequently flavonoids, derived from plant resins. Propolis has a relevant role in increasing the social immunity of bee hives. Experimental evidence indicates that propolis and its components have activity against bacteria, fungi, and viruses. Mechanisms of action on bacteria, fungi, and viruses are known for several propolis components. Experiments have shown that propolis may act synergistically with antibiotics, antifungals, and antivirus drugs, permitting the administration of lower doses of drugs and higher antimicrobial effects. The current trend of growing resistance of microbial pathogens to the available drugs has encouraged the introduction of propolis in therapy against infectious diseases. Because propolis composition is widely variable, standardized propolis extracts have been produced. Successful clinical trials have included propolis extracts as medicine in dentistry and as an adjuvant in the treatment of patients against COVID-19. Present world health conditions encourage initiatives toward the spread of the niche of propolis, not only as traditional and alternative medicine but also as a relevant protagonist in anti-infectious therapy. Production of propolis and other apiary products is environmentally friendly and may contribute to alleviating the current crisis of the decline of bee populations. Propolis production has had social-economic relevance in Brazil, providing benefits to underprivileged people.

Cytotoxicity of Peruvian propolis and Psidium guajava on human gingival fibroblasts, PBMCs and HeLa cells

It is indisputable that every day it is demonstrated that natural products present diverse therapeutic benefits, which has boosted their incorporation within various products for clinical use. However, this must be accompanied by knowledge of their effect on cell lines to ensure their use is safe. The objective of this study was to evaluate the cytotoxic effect of two ethanolic extracts based on Peruvian natural products, on three human cell lines. Cervical cancer cell lines (HeLa), human gingival fibroblasts (HGF-1 - ATCC CRL-2014) (HGF-1) and peripheral blood mononuclear cells (PBMCs) were cultured and subsequently treated with preparations of ethanolic extracts of propolis (EEP) and Psidium guajava (EEG) from a concentration of 50 mg/mL to 0.024 mg/mL, by the 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazole bromide reduction assay. At a concentration of 0.24 mg/mL EEG, viability of 99.7±1.24%, 99.8±2.2% and 99.7±2.7% was observed in HeLa, HGF-1 and PBMCs, respectively; >90% cell viability values were observed with EPP at 0.024 mg/mL, with HGF-1 showing the highest viability (96.9±1.15%). A dose-dependent effect was observed for both extracts with a decrease in cell viability as concentrations increased (up to 50 mg/mL). EEP and EEG extracts at low concentrations do not show cytotoxicity in human cell lines, these findings are an advance in the preclinical evaluation on their safety and open a continuity to further studies for their potential applications in dentistry and medicine.

Cytotoxicity of Peruvian propolis and Psidium guajava on human gingival fibroblasts, PBMCs and HeLa cells

It is indisputable that every day it is demonstrated that natural products present diverse therapeutic benefits, which has boosted their incorporation within various products for clinical use. However, this must be accompanied by knowledge of their effect on cell lines to ensure their use is safe. The objective of this study was to evaluate the cytotoxic effect of two ethanolic extracts based on Peruvian natural products, on three human cell lines. Cervical cancer cell lines (HeLa), human gingival fibroblasts (HGF-1 - ATCC CRL-2014) (HGF-1) and peripheral blood mononuclear cells (PBMCs) were cultured and subsequently treated with preparations of ethanolic extracts of propolis (EEP) and Psidium guajava (EEG) from a concentration of 50 mg/mL to 0.024 mg/mL, by the 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazole bromide reduction assay. At a concentration of 0.24 mg/mL EEG, viability of 99.7±1.24%, 99.8±2.2% and 99.7±2.7% was observed in HeLa, HGF-1 and PBMCs, respectively; >90% cell viability values were observed with EPP at 0.024 mg/mL, with HGF-1 showing the highest viability (96.9±1.15%). A dose-dependent effect was observed for both extracts with a decrease in cell viability as concentrations increased (up to 50 mg/mL). EEP and EEG extracts at low concentrations do not show cytotoxicity in human cell lines, these findings are an advance in the preclinical evaluation on their safety and open a continuity to further studies for their potential applications in dentistry and medicine.

Non-psychotropic Cannabis sativa L. phytocomplex modulates microglial inflammatory response through CB2 receptors-, endocannabinoids-, and NF-κB-mediated signaling

Cannabis sativa L. is increasingly emerging for its protective role in modulating neuroinflammation, a complex process orchestrated among others by microglia, the resident immune cells of the central nervous system. Phytocannabinoids, especially cannabidiol (CBD), terpenes, and other constituents trigger several upstream and downstream microglial intracellular pathways. Here, we investigated the molecular mechanisms of a CBD- and terpenes-enriched C. sativa extract (CSE) in an in vitro model of neuroinflammation. We evaluated the effect of CSE on the inflammatory response induced by exposure to lipopolysaccharide (LPS) in BV-2 microglial cells, compared with CBD and β-caryophyllene (CAR), CB2 receptors (CB2r) inverse and full agonist, respectively. The LPS-induced upregulation of the pro-inflammatory cytokines IL-1β, IL-6, and TNF-α was significantly attenuated by CSE and only partially by CBD, whereas CAR was ineffective. In BV-2 cells, these anti-inflammatory effects exerted by CSE phytocomplex were only partially dependent on CB2r modulation and they were mediated by the regulation of enzymes responsible for the endocannabinoids metabolism, by the inhibition of reactive oxygen species release and the modulation of JNK/p38 cascade with consequent NF-κB p65 nuclear translocation suppression. Our data suggest that C. sativa phytocomplex and its multitarget mechanism could represent a novel therapeutic strategy for neuroinflammatory-related diseases.

In vitro Evaluation of Antiviral Efficacy of a Standardized Hydroalcoholic Extract of Poplar Type Propolis Against SARS-CoV-2

Except for specific vaccines and monoclonal antibodies, effective prophylactic or post-exposure therapeutic treatments are currently limited for COVID-19. Propolis, a honeybee’s product, has been suggested as a potential candidate for treatment of COVID-19 for its immunomodulatory properties and for its powerful activity against various types of viruses, including common coronaviruses. However, direct evidence regarding the antiviral activities of this product still remains poorly documented. VERO E6 and CALU3 cell lines were infected with SARS-CoV-2 and cultured in the presence of 12.5 or 25 μg/ml of a standardized Hydroalcoholic Extract acronym (sHEP) of Eurasian poplar type propolis and analyzed for viral RNA transcription, for cell damage by optical and electron microscopy, and for virus infectivity by viral titration at 2, 24, 48, and 72 h post-infection. The three main components of sHEP, caffeic acid phenethyl ester, galangin, and pinocembrin, were tested for the antiviral power, either alone or in combination. On both cell lines, sHEP showed significant effects mainly on CALU3 up to 48 h, i.e., some protection from cytopathic effects and consistent reduction of infected cell number, fewer viral particles inside cellular vesicles, reduction of viral titration in supernatants, dramatic drop of N gene negative sense RNA synthesis, and lower concentration of E gene RNA in cell extracts. Interestingly, pre-treatment of cells with sHEP before virus inoculation induced these same effects described previously and was not able to block virus entry. When used in combination, the three main constituents of sHEP showed antiviral activity at the same levels of sHEP. sHEP has a remarkable ability to hinder the replication of SARS-CoV-2, to limit new cycles of infection, and to protect host cells against the cytopathic effect, albeit with rather variable results. However, sHEP do not block the virus entry into the cells. The antiviral activity observed with the three main components of sHEP used in combination highlights that the mechanism underlying the antiviral activity of sHEP is probably the result of a synergistic effect. These data add further emphasis on the possible therapeutic role of this special honeybee’s product as an adjuvant to official treatments of COVID-19 patients for its direct antiviral activity.

Bee-Derived Products: Chemical Composition and Applications in Skin Tissue Engineering

Skin tissue regeneration is one of the population's most common problems, and the complications that may appear in the healing process can have detrimental consequences. An alternative to conventional treatments could be represented by sustainable materials based on natural products, such as honey and its derivates (propolis, royal jelly, bee pollen, beeswax, and bee venom). They exhibit significant inhibitory activities against bacteria and have great potential in dermal tissue regeneration. Research in the pharmaceutical field demonstrates that conventional medication combined with bee products can deliver better results. The advantages include minimizing side effects and maintaining the same effectiveness by using low concentrations of antibiotic, anti-inflammatory, or chemotherapy drugs. Several studies suggested that bee products can replace the antimicrobial activity and efficiency of antibiotics, but further investigation is needed to establish a topical mixture's potential, including honey, royal jelly, and propolis. Bee products seem to complete each other's deficiencies, and their mixture may have a better impact on the wound healing process. The topic addressed in this paper highlights the usefulness of honey, propolis, royal jelly, bee pollen, beeswax, and bee venom in the re-epithelization process and against most common bacterial infections.

The antiviral and immunomodulatory activities of propolis: An update and future perspectives for respiratory diseases

Propolis is a complex natural product that possesses antioxidant, anti-inflammatory, immunomodulatory, antibacterial, and antiviral properties mainly attributed to the high content in flavonoids, phenolic acids, and their derivatives. The chemical composition of propolis is multifarious, as it depends on the botanical sources from which honeybees collect resins and exudates. Nevertheless, despite this variability propolis may have a general pharmacological value, and this review systematically compiles, for the first time, the existing preclinical and clinical evidence of propolis activities as an antiviral and immunomodulatory agent, focusing on the possible application in respiratory diseases. In vitro and in vivo assays have demonstrated propolis broad-spectrum effects on viral infectivity and replication, as well as the modulatory actions on cytokine production and immune cell activation as part of both innate and adaptive immune responses. Clinical trials confirmed propolis undeniable potential as an effective therapeutic agent; however, the lack of rigorous randomized clinical trials in the context of respiratory diseases is tangible. Since propolis is available as a dietary supplement, possible use for the prevention of respiratory diseases and their deleterious inflammatory drawbacks on the respiratory tract in humans is considered and discussed. This review opens up new perspectives on the clinical investigation of neglected propolis biological properties which, now more than ever, are particularly relevant with respect to the recent outbreaks of pandemic respiratory infections.

New Insights into Potential Beneficial Effects of Bioactive Compounds of Bee Products in Boosting Immunity to Fight COVID-19 Pandemic: Focus on Zinc and Polyphenols

The coronavirus disease 2019 (COVID-19) is an epidemic caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). Populations at risk as well as those who can develop serious complications are people with chronic diseases such as diabetes, hypertension, and the elderly. Severe symptoms of SARS-CoV-2 infection are associated with immune failure and dysfunction. The approach of strengthening immunity may be the right choice in order to save lives. This review aimed to provide an overview of current information revealing the importance of bee products in strengthening the immune system against COVID-19. We highlighted the immunomodulatory and the antiviral effects of zinc and polyphenols, which may actively contribute to improving symptoms and preventing complications caused by COVID-19 and can counteract viral infections. Thus, this review will pave the way for conducting advanced experimental research to evaluate zinc and polyphenols-rich bee products to prevent and reduce the severity of COVID-19 symptoms.

The Potential Use of Propolis as a Primary or an Adjunctive Therapy in Respiratory Tract-Related Diseases and Disorders: A Systematic Scoping Review

Propolis is a resinous beehive product that is collected by the bees from plant resin and exudates, to protect and maintain hive homeostasis. Propolis has been used by humans therapeutically to treat many ailments including respiratory tract-related diseases and disorders. The aim of the present systematic scoping review is to evaluate the experimental evidence to support the use of propolis as a primary or an adjunctive therapy in respiratory tract-related diseases and disorders. After applying the exclusion criteria, 158 research publications were retrieved and identified from Scopus, Web of Science, Pubmed, and Google Scholar. The key themes of the included studies were pathogenic infection-related diseases and disorders, inflammation-related disorders, lung cancers, and adverse effects. Furthermore, the potential molecular and biochemical mechanisms of action of propolis in alleviating respiratory tract-related diseases and disorders are discussed. In conclusion, the therapeutic benefits of propolis have been demonstrated by various in vitro studies, in silico studies, animal models, and human clinical trials. Based on the weight and robustness of the available experimental and clinical evidence, propolis is effective, either as a primary or an adjunctive therapy, in treating respiratory tract-related diseases.

Optimization of Soybean Meal Fermentation for Aqua-Feed with Bacillus subtilis natto Using the Response Surface Methodology

This study aimed to improve the nutritional value of soybean meal (SBM) by solid-state fermentation (SSF) using Bacillus subtilis natto (B. s. natto) to overcome the limitations of SBM usage in aquafeed. The response surface methodology (RSM) was employed to explore the relationships of fermentation conditions, such as temperature, time, water-substrate ratio, and layer thickness, on the degree of protein hydrolysis (DH) and the crude protein (CP) content. The optimum conditions for achieving the higher DH (15.96%) and CP (55.76%) were 43.82 °C, 62.32 h, 1.08 of water-substrate ratio, and a layer thickness of 2.02 cm. CP and DH in the fermented soybean meal (FSM) increased by 9.8% and 177.1%, respectively, and crude fiber decreased by 14.1% compared to SBM. The protein dispersibility index (PDI) decreased by 29.8%, while KOH protein solubility (KPS) was significantly increased by 17.4%. Flavonoids and total phenolic acid content in FSM were increased by 231.0% and 309.4%, respectively. Neutral protease activity (NPA) also reached a high level (1723.6 U g−1). Total essential amino acids (EAA) in FSM increased by 12.2%, higher than the 10.8% increase of total non-essential amino acids (NEAA), while the total free amino acids content was 12.76 times higher than that of SBM. Major anti-nutritional factors in SBM were significantly reduced during the process, and almost all SBM protein macromolecules were decomposed. Together with the cost-effectiveness of SSF, B. s. natto-fermented SBM products have great potential to improve the plant composition and replace high-cost ingredients in aquafeed, contributing to food security and environmental sustainability.

The effectiveness of propolis extract in reducing dentin hypersensitivity: A systematic review

OBJECTIVE

This systematic review was performed to evaluate the effectiveness of propolis on dentin hypersensitivity reduction.

DESIGN

The search was conducted in Pubmed, Scopus, Web of science, Latin American and Caribbean Health Sciences Literature data base (Lilacs), Brazilian Library in Dentistry (BBO), Embase, and Cochrane Library aiming to identify relevant randomized clinical trials that evaluated the effect of propolis on dentin hypersensitivity. The Cochrane Collaboration tool was used for assessing the risk of bias.

RESULTS

From the total of 63 articles found in the search, six clinical trials were selected. All studies reported that propolis was more effective in reducing hypersensitivity than the placebo. No side effects were observed.

CONCLUSIONS

Overall, propolis extract can be considered an effective, safe and low-cost alternative to reduce the dentin hypersensitivity.

Anti-Viral and Immunomodulatory Properties of Propolis: Chemical Diversity, Pharmacological Properties, Preclinical and Clinical Applications, and In Silico Potential against SARS-CoV-2

Propolis, a resin produced by honeybees, has long been used as a dietary supplement and folk remedy, and more recent preclinical investigations have demonstrated a large spectrum of potential therapeutic bioactivities, including antioxidant, antibacterial, anti-inflammatory, neuroprotective, immunomodulatory, anticancer, and antiviral properties. As an antiviral agent, propolis and various constituents have shown promising preclinical efficacy against adenoviruses, influenza viruses, respiratory tract viruses, herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), human immunodeficiency virus (HIV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Over 300 chemical components have been identified in propolis, including terpenes, flavonoids, and phenolic acids, with the specific constituent profile varying widely according to geographic origin and regional flora. Propolis and its constituents have demonstrated potential efficacy against SARS-CoV-2 by modulating multiple pathogenic and antiviral pathways. Molecular docking studies have demonstrated high binding affinities of propolis derivatives to multiple SARS-CoV-2 proteins, including 3C-like protease (3CLpro), papain-like protease (PLpro), RNA-dependent RNA polymerase (RdRp), the receptor-binding domain (RBD) of the spike protein (S-protein), and helicase (NSP13), as well as to the viral target angiotensin-converting enzyme 2 (ACE2). Among these compounds, retusapurpurin A has shown high affinity to 3CLpro (ΔG = -9.4 kcal/mol), RdRp (-7.5), RBD (-7.2), NSP13 (-9.4), and ACE2 (-10.4) and potent inhibition of viral entry by forming hydrogen bonds with amino acid residues within viral and human target proteins. In addition, propolis-derived baccharin demonstrated even higher binding affinity towards PLpro (-8.2 kcal/mol). Measures of drug-likeness parameters, including metabolism, distribution, absorption, excretion, and toxicity (ADMET) characteristics, also support the potential of propolis as an effective agent to combat COVID-19.

Pharmaceutical Prospects of Bee Products: Special Focus on Anticancer, Antibacterial, Antiviral, and Antiparasitic Properties

Bee products have long been used in traditional healing practices to treat many types of disorders, including cancer and microbial-related diseases. Indeed, several chemical compounds found in bee products have been demonstrated to display anticancer, antibacterial, antiviral, and antiparasitic properties. With the improvement of research tools and in view of recent advances related to bee products, this review aims to provide broad yet detailed insight into the pharmaceutical prospects of bee products such as honey, propolis, bee pollen, royal jelly, bee bread, beeswax, and bee venom, in the domain of cancer and infectious disease management. Available literature confirms the efficacy of these bee products in the alleviation of cancer progression, inhibition of bacterial and viral proliferation, and mitigation of parasitic-related symptoms. With such potentials, bioactive components isolated from the bee products can be used as an alternative approach in the long-run effort to improve humans’ health at a personal and community level.

Antigonococcal Activity of (+)-Medicarpin

Antibiotics are the primary drugs for combating Neisseria gonorrhoeae infections, but with evolving antibiotic resistance of this bacterium, new druggable molecules are needed to stem the tide of this impending public health crisis. Propolis has long been recognized for its antimicrobial properties, being composed of secondary metabolites with antibacterial potential. We herein describe the evaluation of a Jamaican multifloral propolis for antibacterial activity against N. gonorrhoeae. The bioassay-guided evaluation of the ethyl acetate extract yielded (+)-medicarpin (1), whose final structure was elucidated based on spectral analysis and comparison with the known metabolites. Compound (1) selectively inhibited N. gonorrhoeae with a minimum inhibitory concentration value of 0.25 mg/mL, showing an additive effect against N. gonorrhoeae when combined with vancomycin.

Propolis antiviral and immunomodulatory activity: a review and perspectives for COVID-19 treatment

OBJECTIVES

Viral outbreaks are a frequent concern for humans. A great variety of drugs has been used to treat viral diseases, which are not always safe and effective and may induce adverse effects, indicating the need for new antiviral drugs extracted from natural sources. Propolis is a bee-made product exhibiting many biological properties. An overview of viruses, antiviral immunity, propolis safety and its immunomodulatory and antiviral action is reported, as well as perspectives for coronavirus disease 2019 (COVID-19) treatment. PubMed platform was used for data collection, searching for the keywords "propolis", "virus", "antiviral", "antimicrobial" and "coronavirus".

KEY FINDINGS

Propolis is safe and exerts antiviral and immunomodulatory activity; however, clinical trials should investigate its effects on individuals with viral diseases, in combination or not with antiviral drugs or vaccines.

SUMMARY

Regarding COVID-19, the effects of propolis should be investigated directly on the virus in vitro or on infected individuals alone or in combination with antiviral drugs, due to its immunomodulatory and anti-inflammatory action. Propolis administration simultaneously with vaccines should be analyzed, due to its adjuvant properties, to enhance the individuals' immune response. The search for therapeutic targets may be useful to find out how propolis can help to control COVID-19.

Alkali complexes of non-steroidal anti-inflammatory drugs inhibit lung and oral cancers in vitro

Alkali metal complexes (Li, K, and Cs) displayed excellent activities against oral and lung cancer cells with the least toxicity toward normal cells.

Efficacy of propolis-based mouthwashes on dental plaque and gingival inflammation: a systematic review

Background

This systematic review of randomized clinical trials aimed to evaluate the available evidence regarding the efficacy of propolis-based mouthwash on dental plaque and gingival inflammation.

Methods

PubMed, Scopus, and Web of Science databases were searched up to November 2019. Clinical trials that evaluated the efficacy of propolis mouthwashes compared with chlorhexidine (CHX) were included. The primary outcomes comprised dental plaque and/or gingival inflammation. Two authors assessed the risk of bias using the Cochrane tool. Due to marked heterogeneity of the available data, studies were assessed qualitatively, and no metaanalysis was performed.

Results

Nine clinical trials, comprising 333 subjects, fulfilled the eligibility criteria. Most of the included studies showed high risk of bias. Overall, propolis mouthwashes showed good efficacy on plaque and gingivitis in all of the included studies. Out of the eight studies that reported on plaque index, 5 studies found equal efficacy of propolis and CHX in reducing plaque, two studies found superior efficacy in favor of CHX, while one study found superior efficacy in favor of propolis. Six studies assessed gingival inflammation outcome, four of which reported better results with propolis, while two studies reported comparable results.

Conclusions

The results suggest that propolis-based mouthwashes have potential benefits in reducing plaque and gingival inflammation. However, methodological limitations along with small sample sizes in some of the included studies weaken the strength of the evidence. Therefore, further well-designed clinical trials with large sample sizes and adequate follow-up period are recommended to discern the efficacy of propolis mouthwash on plaque and gingivitis.

Effect of Chinese Propolis as an Intracanal Medicament on Post-Operative Endodontic Pain: A Double-Blind Randomized Controlled Trial

Propolis is a potent anti-microbial and natural anti-inflammatory by-product obtained from the beehive. Studies have demonstrated the superior biocompatibility and anti-microbial properties of propolis as compared to calcium hydroxide. However, its effect on postoperative endodontic pain is unknown. Therefore, this study aimed to investigate the impact of Chinese propolis paste as an intracanal medicament on postoperative endodontic pain intensities compared with calcium hydroxide (control) at different time intervals in necrotic teeth with periapical radiolucency. Eighty patients with single-rooted necrotic teeth with visible periapical radiolucency were recruited and randomly allocated to either the calcium hydroxide or propolis groups. After chemo-mechanical preparation and intracanal medicament insertion, patients were given the VAS (visual analogue scale) to record pain scores. Inter-group data were compared and analyzed using two-way repeated measure ANOVA (Bonferroni test). A p-value of < 0.025 was considered significant. In total, >78% of the patients experienced no or only mild post-operative pain in both the groups at all time intervals, without any significant difference in pain scores between the two groups (p > 0.025). An overall flare-up rate of 14.8% was found. The results suggest that either of these medicaments can be used as an inter-appointment medication for the prevention of postoperative pain in necrotic cases.