Antiviral effects of Brazilian green and red propolis extracts on Enterovirus surrogates

In vivo anti-inflammatory activity of BACCHARIN from BRAZILIAN green PROPOLIS

Baccharin is one of the major compounds found in Brazilian green propolis and its botanical source, Baccharis dracunculifolia. Considering the biological effects of propolis and B. dracunculifolia, this study aims to evaluate the analgesic and anti-inflammatory potential of baccharin. The neurodepressor potential was performed by the open field test, analgesia by mechanical stimulation with Dynamic Plantar Aesthesiometer, and by thermal stimulation with Hargreaves apparatus. In addition, the anti-inflammatory potential was achieved by the paw edema assay, histopathological evaluation, and NF-kB expression. Doses of 2.5, 5, and 10 mg/kg of baccharin were evaluated. After euthanasia, plantar tissue was collected and prepared for histology. As a result, analgesic activity was observed at a dose of 10 mg/kg of baccharin in thermal stimulation under an inflammatory process and anti-inflammatory potential at a dose of 5 mg/kg of baccharin from the second hour in the paw edema test. A decrease in cellular infiltrate and down-modulation of NF-kB, besides the reduction of edema in the histopathology was observed. There was no evidence of kidney and liver toxicity and neurodepressive potential at the doses tested. Thus, baccharin has a promising anti-inflammatory effect possibly associated with antiedematogenic activity by inhibiting mediators such as prostaglandins, inhibiting the migration of polymorphonuclear cells, and modulating NF-kB expression.

The influence of propolis plus Hyoscyamus niger L. against COVID-19: A phase II, multicenter, placebo-controlled, randomized trial

The incubation period of COVID-19 symptoms, along with the proliferation and high transmission rate of the SARS-CoV-2 virus, is the cause of an uncontrolled epidemic worldwide. Vaccination is the front line of prevention, and antiinflammatory and antiviral drugs are the treatment of this disease. In addition, some herbal therapy approaches can be a good way to deal with this disease. The aim of this study was to evaluate the effect of propolis syrup with Hyoscyamus niger L. extract in hospitalized patients with COVID-19 with acute disease conditions in a double-blinded approach. The study was performed on 140 patients with COVID-19 in a double-blind, randomized, and multicentral approach. The main inclusion criterion was the presence of a severe type of COVID-19 disease. The duration of treatment with syrup was 6 days and 30 CC per day in the form of three meals. On Days 0, 2, 4, and 6, arterial blood oxygen levels, C-reactive protein (CRP), erythrocyte sedimentation rate, and white blood cell, as well as the patient's clinical symptoms such as fever and chills, cough and shortness of breath, chest pain, and other symptoms, were recorded and analyzed. Propolis syrup with H. niger L. significantly reduces cough from the second day, relieving shortness of breath on the fourth day, and significantly reduces CRP, weakness, and lethargy, as well as significantly increased arterial blood oxygen pressure on the sixth day compared to the placebo group (p < 0.05). The results in patients are such that in the most severe conditions of the disease 80% < SpO2 (oxygen saturation), the healing process of the syrup on reducing CRP and increasing arterial blood oxygen pressure from the fourth day is significantly different compared with the placebo group (p < 0.05). The use of syrup is associated with a reduction of 3.6 days in the hospitalization period compared with the placebo group. Propolis syrup with H. niger L. has effectiveness in the viral and inflammatory phases on clinical symptoms and blood parameters and arterial blood oxygen levels of patients with COVID-19. Also, it reduces referrals to the intensive care unit and mortality in hospitalized patients with COVID-19. So, this syrup promises to be an effective treatment in the great challenge of COVID-19.

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.

Antiviral Potential of Specially Selected Bulgarian Propolis Extracts: In Vitro Activity against Structurally Different Viruses

Propolis is a natural mixture of resins, wax, and pollen from plant buds and flowers, enriched with enzymes and bee saliva. It also contains various essential oils, vitamins, mineral salts, trace elements, hormones, and ferments. It has been found that propolis possesses antimicrobial, antiviral, and anti-inflammatory properties. We have studied the antiviral activity of six extracts of Bulgarian propolis collected from six districts of Bulgaria. The study was conducted against structurally different viruses: human coronavirus strain OC-43 (HCoV OC-43) and human respiratory syncytial virus type 2 (HRSV-2) (enveloped RNA viruses), human herpes simplex virus type 1 (HSV-1) (enveloped DNA virus), human rhinovirus type 14 (HRV-14) (non-enveloped RNA virus) and human adenovirus type 5 (HadV-5) (non-enveloped DNA virus). The influence of the extracts on the internal replicative cycle of viruses was determined using the cytopathic effect (CPE) inhibition test. The virucidal activity, its impact on the stage of viral adsorption to the host cell, and its protective effect on healthy cells were evaluated using the final dilution method, making them the focal points of interest. The change in viral infectivity under the action of propolis extracts was compared with untreated controls, and Δlgs were determined. Most propolis samples administered during the viral replicative cycle demonstrated the strongest activity against HCoV OC-43 replication. The influence of propolis extracts on the viability of extracellular virions was expressed to a different degree in the various viruses studied, and the effect was significantly stronger in those with an envelope. Almost all extracts significantly inhibited the adsorption step of the herpes virus and, to a less extent, of the coronavirus to the host cell, and some of them applied before viral infection demonstrated a protective effect on healthy cells. Our results enlarge the knowledge about the action of propolis and could open new perspectives for its application in viral infection treatment.

How to Tackle Bacteriophages: The Review of Approaches with Mechanistic Insight

Bacteriophage-based applications have a renaissance today, increasingly marking their use in industry, medicine, food processing, biotechnology, and more. However, phages are considered resistant to various harsh environmental conditions; besides, they are characterized by high intra-group variability. Phage-related contaminations may therefore pose new challenges in the future due to the wider use of phages in industry and health care. Therefore, in this review, we summarize the current knowledge of bacteriophage disinfection methods, as well as highlight new technologies and approaches. We discuss the need for systematic solutions to improve bacteriophage control, taking into account their structural and environmental diversity.

Potential in vitro anti-periodontopathogenic, anti-Chikungunya activities and in vivo toxicity of Brazilian red propolis

Bacterial and viral infections are serious public health issue. Therefore, this study aimed to evaluate the antibacterial, antibiofilm and antiviral potential of the Brazilian Red Propolis (BRP) crude hydroalcoholic extract, fractions, and isolated compounds, as well as their in vivo toxicity. The antibacterial activity was evaluated by determining the Minimum Inhibitory Concentration and the antibiofilm activity by determining the Minimum Inhibitory Concentration of Biofilm (MICB₅₀). The viable bacteria count (Log₁₀ UFC/mL) was also obtained. The antiviral assays were performed by infecting BHK-21 cells with Chikungunya (CHIKV) nanoluc. The toxicity of the BRP was evaluated in the Caenorhabditis elegans animal model. The MIC values for the crude hydroalcoholic extract sample ranged from 3.12 to 100 μg/mL, while fractions and isolated compounds the MIC values ranged from 1.56 to 400 μg/mL.The BRP crude hydroalcoholic extract, oblongifolin B, and gutiferone E presented MICB₅₀ values ranging from 1.56 to 100 μg/mL against monospecies and multispecies biofilms. Neovestitol and vestitol inhibited CHIKV infection by 93.5 and 96.7%, respectively. The tests to evaluate toxicity in C. elegans demonstrated that the BRP was not toxic below the concentrations 750 μg/mL. The results constitute an alternative approach for treating various infectious diseases.

Toxicological and chemoprevention studies of Dalbergia ecastaphyllum (L.) Taub. stem, the botanical source of Brazilian red propolis

OBJECTIVES

Dalbergia ecastaphyllum (L.) Taub. is a semi-prostrate species associated with estuaries, mangroves and dunes. This plant species has great ecological and economic importance, especially concerning apiculture pasture and Brazilian red propolis production. In this study, non-clinical toxicological evaluations of the hydroalcoholic extract of D. ecastaphyllum stems (DEHE), the resin production source, were conducted. In addition, the action of DEHE on genomic instability and colon carcinogenesis was investigated.

METHODS AND RESULTS

The extract's chemical profile was analysed by HPLC, and medicarpin, vestitol and neovestitol were found as major compounds. DEHE showed an IC50 equivalent to 373.2 µg/ml and LC50 equal 24.4 mg/L, when evaluated using the XTT colorimetric test and the zebrafish acute toxicity assay, respectively. DEHE was neither genotoxic nor cytotoxic at the highest dose, 2000 mg/kg, by peripheral blood micronucleus test. The treatments DEHE (6 and 24 mg/kg) led to the reduction of micronuclei induced by doxorubicin (DXR) in mice. Furthermore, significantly higher serum levels of reduced glutathione were observed in animals treated with DEHE plus DXR, revealing an antioxidant effect. Treatments with DEHE (48 mg/kg) led to a significant reduction in pre-neoplastic lesions induced by the 1,2-dimethylhydrazine (DMH) carcinogen in the rat colon. Immunohistochemical analysis revealed significantly lower levels of expression of COX-2 (86%) and PCNA (83%) in the colon of rats treated with DEHE plus DMH, concerning those treated with the carcinogen.

CONCLUSIONS

These results indicate the involvement of anti-inflammatory and antiproliferative pathways in the protective effect of DEHE.

Evaluation of the Skin-Sensitizing Potential of Brazilian Green Propolis

Propolis is a resinous mixture produced by bees from their secretions and plant material, so its composition varies depending on its botanical origin. Propolis has several beneficial bioactivities, but its skin sensitization properties have long been suspected. Nevertheless, the skin sensitization potency of Brazilian green propolis (BGP) has not been scientifically evaluated. Here, we used scientifically reliable tests to evaluate it. In vitro antigenicity test based on the human cell line activation test (OECD TG 442E) was performed by measuring the expression of CD54 and CD86, which are indicators of the antigenicity of test substances, on THP-1 and DC2.4 cells. BGP did not affect the expression of either marker on THP-1 cells, but upregulated the expression of CD86 on DC2.4 cells, suggesting that BGP may be a skin sensitizer. Then, we performed local lymph node assay (LLNA, OECD TG 429) as a definitive in vivo test. LLNA showed that 1.70% BGP primed skin sensitization and is a "moderate sensitizer". Our results indicate scientific proof of the validity of arbitrary concentrations (1-2%), which have been used empirically, and provide the first scientific information on the safe use of BGP.

Comparison of the Biological Potential and Chemical Composition of Brazilian and Mexican Propolis

Propolis is a resinous substance collected by bees from plants and its natural product is available as a safe therapeutic option easily administered orally and readily available as a natural supplement and functional food. In this work, we review the most recent scientific evidence involving propolis from two countries (Brazil and Mexico) located in different hemispheres and with varied biomes. Brazil has a scientifically well documented classification of different types of propolis. Although propolis from Brazil and Mexico present varied compositions, they share compounds with recognized biological activities in different extraction processes. Gram-negative bacteria growth is inhibited with lower concentrations of different types of propolis extracts, regardless of origin. Prominent biological activities against cancer cells and fungi were verified in the different types of extracts evaluated. Antiprotozoal activity needs to be further evaluated for propolis of both origins. Regarding the contamination of propolis (e.g., pesticides, toxic metals), few studies have been carried out. However, there is evidence of chemical contamination in propolis by anthropological action. Studies demonstrate the versatility of using propolis in its different forms (extracts, products, etc.), but several potential applications that might improve the value of Brazilian and Mexican propolis should still be investigated.

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.

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.

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.

Dietary Modulation of Bacteriophages as an Additional Player in Inflammation and Cancer

Natural compounds such as essential oils and tea have been used successfully in naturopathy and folk medicine for hundreds of years. Current research is unveiling the molecular role of their antibacterial, anti-inflammatory, and anticancer properties. Nevertheless, the effect of these compounds on bacteriophages is still poorly understood. The application of bacteriophages against bacteria has gained a particular interest in recent years due to, e.g., the constant rise of antimicrobial resistance to antibiotics, or an increasing awareness of different types of microbiota and their potential contribution to gastrointestinal diseases, including inflammatory and malignant conditions. Thus, a better knowledge of how dietary products can affect bacteriophages and, in turn, the whole gut microbiome can help maintain healthy homeostasis, reducing the risk of developing diseases such as diverse types of gastroenteritis, inflammatory bowel disease, or even cancer. The present review summarizes the effect of dietary compounds on the physiology of bacteriophages. In a majority of works, the substance class of polyphenols showed a particular activity against bacteriophages, and the primary mechanism of action involved structural damage of the capsid, inhibiting bacteriophage activity and infectivity. Some further dietary compounds such as caffeine, salt or oregano have been shown to induce or suppress prophages, whereas others, such as the natural sweeter stevia, promoted species-specific phage responses. A better understanding of how dietary compounds could selectively, and specifically, modulate the activity of individual phages opens the possibility to reorganize the microbial network as an additional strategy to support in the combat, or in prevention, of gastrointestinal diseases, including inflammation and cancer.

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.

Preparation, statistical optimization, in vitro characterization, and in vivo pharmacological evaluation of solid lipid nanoparticles encapsulating propolis flavonoids: a novel treatment for skin edema

Propolis is a natural resinous product and exerts anti-inflammatory properties. The aim of this study is formulation and characterization of solid lipid nanoparticles (SLNs) encapsulating propolis flavonoids (PFs), intended for topical treatment of skin edema. The nanoparticles were prepared and statistically optimized using Box-Behnken response surface methodology. The in vitro release profile of the optimized nanoparticles was investigated. Cytotoxicity of nanoparticles on HSF-PI 18 cell line was determined. Permeation and penetration of nanoparticles across the incised skin were measured. Finally, the nanoparticles were incorporated into a pharmaceutical hydrogel formulation and the in vivo efficacy in reduction of skin edema was determined. The size, PdI, zeta potential, entrapment efficiency (EE%) and loading efficiency (LE %) of the optimized nanoparticles were 111.3 ± 19.35 nm, 0.34 ± 0.005, -24.17 ± 3.3 mV, 73.5 ± 0.86%, and 3.2 ± 0.27%, respectively. Data obtained through in vitro release study suggested a burst release followed by a prolonged release behavior up to 24 h post incubation time interval. The prepared SLNs exhibited no cytotoxicity on HSF-PI 18 cell line. Ex vivo permeation and penetration study of nanoparticles across the incised skin showed approximately a 2.5-fold and a 3-fold increase in cumulative amount of transport and cumulative amount of skin penetration, respectively. Finally, in vivo studies in rat models, showed a threefold reduction in volume of the edema in animals treated with SLNs. The obtained data revealed that the prepared SNs entrapping PFs, exert high skin targeting effects, prolonged anti-inflammatory properties and therefore high efficiency in treatment of skin edema.