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.

Chemical composition and antimicrobial activity of two extract of propolis against isolates of Staphylococcus spp. and multiresistant bacterials / Composição química e atividade antimicrobiana de dois extratos de própolis contra isolados de Staphylococcus spp. e bactérias multirresistentes

There is a growing need to discover and develop alternative therapies for the treatment of mastitis caused by Staphylococcus spp. and multidrug-resistant bacterial infections. This study examined the chemical composition and antimicrobial potential of two propolis extracts (EPA and EPB) against seventy-seven isolates of Staphylococcus spp. obtained from subclinical bovine mastitis; three clinical strains of MRSA and two from clinical strains of S. aureus ATCC, identified as S. aureus ATCC 6538 and S. aureus ATCC 25923. The total phenolic content was determined by the Folin-Ciocalteau method, the total flavonoid content by the Dowd method and the phenolic profile was quantified by HPLC-DAD. The MBC values of the extracts were evaluated by broth microdilution method. The amount of total phenolic and flavonoid compounds was higher in EPA than EPB. Both extracts revealed the presence of caffeic, coumaric, cinnamic, ferulic and 3,4-dihydroxybenzoic acids, with higher concentrations of coumaric and cinnamic acids. Staphylococcus spp. isolates were susceptible to EPA (90.9%), EPB (83.1%) and oxacillin (80.5%). The oxacillin susceptible isolates were also susceptible to EPA (70.1%) and EPB (80.6%), whereas those oxacillin-resistant strains were also susceptible to EPA (40.0%) and to EPB (26.7%). MBC ranged from 34.3 to 68.7µm/mL for EPA and from 68.7 to 137.5µg/mL for EPB. Both extracts inhibited significantly (100%) the clinical strains of MRSA, S. aureus ATCC 6538 and S. aureus ATCC 25923 at the concentration of 68.7µg/mL. It is concluded that both extracts of propolis, whose main constituents are coumaric and cinnamic acids, have high antimicrobial activity against the microorganisms studied, and EPA also against oxacillin-resistant strains. These findings reinforce its potential use for the treatment of bovine mastitis.(AU)

É cada vez mais oportuna a necessidade de descobrir e desenvolver terapias alternativas para tratamento da mastite causada por Staphylococcus spp. e de infecções bacterianas multirresistentes. Este estudo examinou a composição química e o potencial antimicrobiano de dois extratos etanólicos de própolis (EPA e EPB) contra setenta e sete isolados de Staphylococcus spp. obtidos a partir de mastite bovina subclínica; três estirpes clínicas de MRSA e duas de linhagens clínicas de S. aureus ATCC, identificadas como, S. aureus ATCC 6538 e S. aureus ATCC 25923, ambas metacilina resistentes. O teor total de fenólicos foi determinado pelo método de Folin-Ciocalteau, o teor de flavonoides totais pelo método Dowd e o perfil fenólico foi quantificado por HPLC-DAD. CBM dos extratos foi avaliada pelo método de microdiluição em caldo. A quantidade total de compostos fenólicos e flavonoides foi maior no EPA do que no EPB. Ambos os extratos revelaram a presença dos ácidos cafeico, cumárico, cinâmico, ferúlico e 3,4-di-hidroxibenzóico, com maiores concentrações de ácidos cumárico e cinâmico. Os isolados de Staphylococcus spp. foram sensíveis a EPA (90,9%), EPB (83,1%) e oxacilina (80,5%). Os isolados suscetíveis à oxacilina também foram suscetíveis ao EPA (70,1%) e ao EPB (80,6%), enquanto os do resistente à oxacilina foram suscetíveis ao EPA (40,0%) e ao EPB (26,7%). MBC variou de 34,3 a 68,7µm/mL para EPA e de 68,7 a 137,5µg/mL para EPB. Ambos os extratos inibiram significativamente (100%) as linhagens clínicas de MRSA, S. aureus ATCC 6538 e S. aureus ATCC 25923 na concentração de 68,7µg/mL. Conclui-se que os extratos etanólicos da própolis, cujos principais constituintes são os ácidos cumário e cinâmico, possuem atividade antimicrobiana contra os micro-organismos estudados, e o EPA também contra as cepas resistentes à oxacilina. Estes achados reforçam seu potencial uso para o tratamento da mastite bovina.(AU)

Beneficial Effects of Poplar Buds on Hyperglycemia, Dyslipidemia, Oxidative Stress, and Inflammation in Streptozotocin-Induced Type-2 Diabetes.

The effects of propolis on blood glucose regulation and the alleviation of various complications caused by diabetes have been widely studied. The main source of propolis in the northern temperate zone is poplar buds. However, there is limited research on the antidiabetic activity of poplar buds. In order to evaluate the effect of poplar buds on type-2 diabetes, crude extract and 50% fraction of poplar buds were used to feed streptozotocin-induced type-2 diabetic mice. The results showed that 50% fraction could increase insulin sensitivity and reduce insulin resistance, as well as decrease the levels of fasting blood glucose, glycated hemoglobin, and glycosylated serum proteins in diabetic mice. Compared with the model control group, the 50% fraction-treated group showed significant decreases of malondialdehyde (MDA) and increases of superoxide dismutase (SOD) in serum and liver homogenate. Moreover, 50% fraction could significantly decrease total cholesterol (TC), alleviate abnormal lipid metabolism, and enhance antioxidant capacity in the serum. For inflammatory factors, feeding of 50% fraction could also reduce the levels of interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), monocyte chemotactic protein 1 (MCP-1), and cyclooxygenase-2 (COX-2) in liver homogenate. Taken together, our results suggest that crude extract and 50% fraction of poplar buds, particularly the latter, can decrease blood glucose levels and insulin resistance, and 50% fraction can significantly relieve dyslipidemia, oxidative stress, and inflammation caused by type-2 diabetes.

Anti-inflammatory activity of flavonoids in Nepalese propolis is attributed to inhibition of the IL-33 signaling pathway.

Propolis has been used in folk medicine to improve health and prevent inflammatory diseases; however, the components that exhibit its anti-inflammatory activity remain unknown. We herein investigated the effects of flavonoids isolated from Nepalese propolis on the IL-33 signaling pathway to clarify the anti-inflammatory mechanism involved. Of the 8 types of flavonoids isolated from Nepalese propolis, 4 types of compounds, such as 3',4'-dihydroxy-4-methoxydalbergione, 4-methoxydalbergion, cearoin, and chrysin, markedly inhibited the IL-33-induced mRNA expression of inflammatory genes including IL-6, TNFα and IL-13 in bone marrow-derived mast cells (BMMC). These four flavonoids also inhibited the IL-33-induced activation of nuclear factor κB (NF-κB), which was consistent with their inhibitory effects on cytokine expression. The effects of these flavonoids are attributed to inhibition of IL-33-induced activation of IKK, which leads to the degradation of IκBα and nuclear localization of NF-κB. On the other hand, other flavonoids isolated from Nepalese propolis, such as isoliquiritigenin, plathymenin, 7-hydroxyflavanone, and (+)-medicarpin, had no effect on the IL-33 signaling pathway or cytokine expression. Therefore, these results indicate that 3',4'-dihydroxy-4-methoxydalbergione, 4-methoxydalbergion, cearoin, and chrysin are the substances responsible for the anti-inflammatory activity of Nepalese propolis.

Immunomodulatory properties of green propolis.

Propolis is a resinous material collected by honeybees from numerous plants and serves as a defense against intruders. Because of its relevant curative properties, it is now gaining popularity in health foods and in cosmetic products. Understanding the underlying molecular mechanisms of phytochemicals has become a good strategy in bioprospection for new anti-inflammatory compounds. The biological activity of propolis derives from its high levels of phenolic acids, while flavonoids are thought to account for the activity of propolis extracts. The comprehension of the relationship between propolis and the immune system has progressed in the last years, recent articles have provided important contributions to this investigation field. Studies have shown that propolis suppressed the "IL-6-induced phosphorylation of signal transducer and STAT3", an essential cytokine-activated transcription factor in Th17 development. Therefore, action mechanisms of "propolis on Th17 differentiation could be instrumental in controlling disturbed cytokine networks in inflammation, autoimmune diseases, and infections." The use of propolis has been proposed in some patents as: WO201363714; CN102885854, WO2013142936, US20130266521, and US20130129808, which are related to the treatment of dental diseases; adjuvant in anti-cancer treatment; in cosmetic products; as an anti-inflammatory agent and natural antibiotic. Although there are many publications regarding the propolis efficacy, its applicability to human health and mechanisms of action are not completely understood, creating opportunities for new studies.

Propóleos, inmunología y enfermedad de Peyronie / Propolis, Immunology and Peyronie's disease

Introducción: En varias investigaciones anteriores publicadas, hemos demostrado mejoría clínica de la enfermedad de Peyronie (EP) con propóleos. De las propiedades del propóleos, la inmunoestabilizadora es la que, hipotéticamente, produce dichos efectos. Objetivos: Analizar y conocer la correlación de la EP, el propóleos, la inmunología y la mejoría clínica. Material y métodos: Estudio prospectivo, pareado, ensayo clínico. Se estudian 30 pacientes. Dosis de 900 mg de propóleos diario durante 6 meses. Variables estudiadas: edad, raza, dirección de la curvatura, dolor, tamaño de la placa (pre y postratamiento) medida por exploración física, ecografía y ángulo de curvatura, dosificaciones de IgA, IgG, IGm, C3, C4, factor reumatoideo, proteína C reactiva, pruebas cutáneas. Resultados: La edad no presentó un predominio significativo. En cambio respecto a la raza, el 70% eran blancos. La curvatura, predominantemente, fue hacia arriba (40%). Con dolor consultó el 53,3%, siendo más manifiesto en los que tenían una curvatura hacia arriba (8 de los 12 casos). La modificación promedio en el grado de angulación (pre vs. postratamiento) fue de 38,1 g (pretratamiento) vs. 29,5 g (postratamiento) (p < 0,001). La variación en el tamaño de la placa, expresada en medición promedio de cada una de las 3 dimensiones, fue: medición física (cm) (1,9 × 1,3 × 1,3 pretratamiento) vs. (1,5 × 1,1 × 1,1 postratamiento) (p < 0,008, p < 0,0003, p < 0,0003); medición ecográfica (mm) (12,6 × 7,8 × 11,4 pretratamiento) vs. (11,7 × 7,5 × 5,1 postratamiento), p < 0,005). Pruebas humorales inmunológicas: C3 bajo en la mayoría de los pacientes. C4 rango normal. Aumento de C3 postratamiento a niveles normales y en las restantes que tenían niveles normales, pero en rangos limítrofes normales inferiores, aumentaron postratamiento (IGg, IGm, IGa y C4): en la inmunidad celular pretratamiento, pacientes inmunodeprimidos 18, moderadamente deprimidos 2 y normales 10 (33,3%). Postratamiento, sólo 1 paciente inmunodeprimido. Discusión: Al evaluar las variables principales de la investigación, observamos que la angulación del pene después del tratamiento durante 6 meses con propóleos se redujo notablemente, así como el tamaño de la placa medida físicamente por el investigador, y ecográficamente por el imagenólogo, se redujo al finalizar el tratamiento. Y, finalmente, analizando el sistema inmunológico de los pacientes tratados antes y después del tratamiento, los que lo tenían deprimido en mayor o menor grado se normalizaron, y otros pacientes cuyas cifras en los test eran normales, pero en el límite inferior de los valores referenciales, aumentaron al finalizar el tratamiento. Conclusiones: Existe una relación de inmunología deprimida en pacientes afectos de EP. La mejoría clínica de estos pacientes con EP, tratados con propóleos, se asocia a la mejoría inmunológica. Con un tratamiento de propóleos, se reduce el ángulo de curvatura del pene, la placa disminuye su tamaño y mejora su estado inmunológico deficiente (AU)

Introduction: In several previously published articles, we have shown clinical improvement in Peyronie's disease (PD) with propolis. Among the properties of propolis, immunostabilization is that which hypothetically corresponds to these effects. Objectives: To analyze and determine the associations among PD, propolis, immunology and clinical improvement. Material and methods: We performed a prospective, paired clinical trial of 30 patients. A dose of 900 mg propolis daily was administered for 6 months. The variables studied were age, race, direction of the curvature, pain, size of the plaque (pre- and post-treatment), as measured by physical examination, ultrasound and angle of curvature; levels of IgA, IgG, IGm, C3, C4, rheumatoid factor and C-reactive protein, and the results of skin tests. Results: There was no predominant age, while 70% of the patients were white. The curvature was predominantly upwards (40%).Pain was present in 53.3%, and was more frequent when the curvature was upwards (8 of the 12 patients). The mean change in the degree of angulation (pre- vs. post- treatment) was 38.1º(pre-treatment) vs. 29.5º(post-treatment) (p < 0.001). The variation in the size of the plaque, expressed as the mean of each of the three dimensions was as follows: physical measurement (cm) (1.9×1.3×1.3 pre-treatment) vs. (1.5×1.1×1.1 post-treatment) (p<0.008, p<0.0003, p<0.0003); ultrasound measurement (mm) (12.6x7.8×11.4(pre-treatment) vs. (11.7×7.5×5.1 post-treatment) (p < 0.005). The results of humoral immunological tests were as follows: C3 levels were low in the majority of the patients; C4 levels were within the normal range; C3 concentrations increased after treatment to within the normal range and levels increased after treatment in the remaining patients who had levels at the lower limit of normal before treatment. The results of cellular immunity tests (IGg, IGm, IGa and C4) showed that before treatment 18 patients were immunodepressed, two showed moderate immunodepression and 10 showed normal cellular immune function (33.3%). After treatment, only one patient was immunodepressed. Discussion: On evaluating the main variables, we found that the angle of the penis after 6 months of treatment with propolis was significantly reduced. The size of the plaque measured physically by the physician and sonographically by the sonographer was also reduced at the end of the treatment. In patients who were immunodepressed before treatment, immune function returned to normal to a greater or lesser extent. Patients with low values before treatment showed improved immune function after treatment. Conclusions: There is an association between immunodepression and PD. The clinical improvement in patients with PD treated with propolis was associated with improved immune function. Propolis reduces the angle of penile curvature and the size of the plaque and improves immune function (AU)

The effects of propolis and its isolated compounds on cytokine production by murine macrophages.

Since propolis and phenolic compounds, such as cinnamic and coumaric acids, have several biological properties, their immunomodulatory effect on cytokine production (IL-1ß, IL-6 and IL-10) was investigated. Peritoneal macrophages from BALB/c mice were incubated with propolis, coumaric and cinnamic acids in different concentrations and the concentrations that inhibited cytokine production were tested before or after macrophage challenge with LPS, to evaluate a possible immunomodulatory action. Propolis and the acids stimulated IL-1ß production, while IL-6 production was significantly inhibited after incubation with propolis (5, 50 and 100 µg/well), coumaric and cinnamic acids (50 and 100 µg/well). In LPS-challenge protocols, inhibitory concentrations of cinnamic and coumaric acids after LPS incubation prevented efficiently its effects on IL-6 production, whereas propolis inhibited LPS effects both before and after its addition. Propolis, coumaric and cinnamic acids (50 and 100 µg/well) inhibited IL-10 production as well. Both acids showed a similar inhibitory activity on IL-10 production when added after LPS challenge, while propolis counteracted LPS action when added before and after LPS incubation. Propolis modulated the immune/inflammatory response, depending on the concentration. Its efficiency may occur due to the synergistic effect of its compounds, and cinnamic and coumaric acids may be involved in the action of propolis on cytokine production.

Indicadores físico-químicos e atividade antibacteriana de própolis marrom frente à Escherichia coli / Physico-chemical indicators and antibacterial activity of brown propolis against Escherichia coli

The activity of 23 samples of ethanolic brown propolis, from the State of Mato Grosso, was investigated against Escherichia coli ATCC 25922. The values of physical and chemical parameters showed significant variation among samples. The percentage of dry extract ranged from 2.6 to 27.6 percent. The index of oxidation varied from 3 to 519 seconds. All samples showed the percentage of wax higher than the limit preconized by the legislation, with values varying from 3.4 to 74.6 percent. The quantification of phenolic and flavonoid compounds, responsible for antimicrobial activity, ranged from 0.1 to 5.0 (w/w) and 0.02 to 0.66 (w/w), respectively, being that the higher the index of phenolic compounds the larger the zones of inhibition. Antibacterial activity was observed in seven out of the 23 samples, demonstrating zones of inhibition ranging from 10 to 11.3mm. For these active samples, the minimum inhibitory concentration was determined, ranging from 125 to 1000mg/mL. The value of MIC in 42.9 percent of these samples was 250mg/mL. These results contribute to the establishment of physical and chemical parameters for the regulation of brown propolis and indicate possible therapeutic applicability in the development of formulations for the treatment of infections caused by E. coli.

Epimedium polysaccharide and propolis flavone can synergistically stimulate lymphocyte proliferation in vitro and enhance the immune responses to ND vaccine in chickens.

Four prescriptions, epimedium flavone plus propolis flavone (EF-PF), epimedium flavone plus propolis extracts (EF-PE), epimedium polysaccharide plus propolis flavone (EP-PF) and epimedium polysaccharide plus propolis extracts (EP-PE), were prepared and their immune-enhancing effects were compared. In test in vitro, the effects of them on chicken peripheral lymphocyte proliferation were determined by MTT method. The results showed that EP-PF group presented the highest stimulating index at most concentrations. In immune test, 300 14-day-old chickens were randomly divided into six groups and vaccinated with ND vaccine except for blank control (BC) group, re-challenged at 28 days of age. At the same time of the first vaccination, the chickens in four experimental groups were injected, respectively, with four prescriptions. The changes of the lymphocyte proliferation and antibody titer were determined. On day 28 after the first vaccination, the chickens except for BC group were challenged with NDV, the immune protective effect was observed. The results displayed that in EP-PF group, the antibody titers, lymphocyte proliferation and protective rate were the highest, the morbidity and mortality were the lowest. In dose test, 14-day-old chickens were randomly divided into five groups. The treatment and determinations were the same as the immune test except that the chickens in experimental groups were injected, respectively, with high, medium and low doses of EP-PF. The results revealed that in medium dose group, the antibody titers, lymphocyte proliferation and protective rate were the highest, the morbidity and mortality were the lowest. These results indicated that EP and PF possessed synergistically immune enhancement, EP-PF had the best efficacy, especially at medium dose, and would be expected to exploit into a new-type immunopotentiator.

Propolis immunomodulatory action in vivo on Toll-like receptors 2 and 4 expression and on pro-inflammatory cytokines production in mice.

Propolis is a bee product and its immunomodulatory action has been the subject of intense investigation lately. The recent discovery and characterization of the family of Toll-like receptors (TLR) have triggered a great deal of interest in the field of innate immunity due to their crucial role in microbial recognition and development of the adaptive immune response. This work aimed to evaluate propolis's effect on TLR-2 and TLR-4 expression and on the production of pro-inflammatory cytokines (IL-1beta and IL-6). Male BALB/c mice were treated with propolis (200 mg/kg) for three consecutive days, and TLR-2 and TLR-4 expression as well as IL-1beta and IL-6 production were assessed in peritoneal macrophages and spleen cells. Basal IL-1beta production and TLR-2 and TLR-4 expression were increased in peritoneal macrophages of propolis-treated mice. TLR-2 and TLR-4 expression and IL-1beta and IL-6 production were also upregulated in the spleen cells of propolis-treated mice. One may conclude that propolis activated the initial steps of the immune response by upregulating TLRs expression and the production of pro-inflammatory cytokines in mice, modulating the mechanisms of the innate immunity.

Autosensitization dermatitis associated with propolis-induced allergic contact dermatitis.

Propolis is a beehive product known for its anti-inflammatory properties. With its growing use, propolis-induced contact dermatitis is increasing. While the dermatitis mostly occurs on areas directly exposed to propolis, our case presented an additional eczema at a site distant from the primary propolis-induced contact dermatitis twice in the same individual. We diagnosed it as an autosensitization dermatitis associated with propolis-induced allergic contact dermatitis.

Effect of propolis, some isolated compounds and its source plant on antibody production.

Propolis is a beehive product with a very complex chemical composition, widely used in folk medicine because of its several therapeutic activities. Its biological properties and chemical composition may vary according to the geographic location and to the different plant sources. The possible mechanism of action of propolis as well as of its active compounds has been the subject of researchers in recent years. In this work, first we reported the results of our study on the seasonal effect of the immunomodulatory action of propolis on antibody production in bovine serum albumin (BSA)-immunized rats. Then, we compared the effect of Brazilian and Bulgarian propolis, some isolated compounds and Baccharis extract on anti-BSA antibody levels. Based on the results, we conclude that propolis stimulates antibody production, independently of the season and geographic origin. Caffeic acid, quercetin and Baccharis extract had no effect on antibody production, although the importance of isolated compounds is well reported in other biological assays. Propolis action is a consequence of plant-derived products with synergic effects, while isolated compounds or extracts from its plant sources had no effect in this assay.

The effect of herbal remedies on the production of human inflammatory and anti-inflammatory cytokines.

BACKGROUND: Some herbal remedies are sold as food additives and are believed to have immune-enhancing properties. OBJECTIVES: To study the effect of five herbal remedies--Sambucol Black Elderberry Extract, Sambucol Active Defense Formula and Sambucol for Kids (with known antiviral properties), Protec and Chizukit N (containing propolis and Echinacea, claimed to be immune enhancers)--on the production of cytokines, one of the main components of the immune system. METHODS: The production of four inflammatory cytokines (interleukin-1 beta, tumor necrosis factor alpha, and IL-6 and IL-8) and one anti-inflammatory cytokine (IL-10) was tested using blood-derived monocytes from 12 healthy donors. RESULTS: The Sambucol preparations increased the production of five cytokines (1.3-6.2 fold) compared to the control. Protec induced only a moderate production of IL-8 (1.6 fold) and IL-10 (2.3 fold) while Chizukit N caused only a moderate increase in IL-10 production (1.4 fold). Both Protec and Chizukit N caused moderate decreases in IL-1 beta, TNF alpha and IL-6 production. Lipopolysaccharide, a known activator of monocytes, induced the highest levels of cytokine production (3.6-10.7 fold). CONCLUSIONS: The three Sambucol formulations activate the healthy immune system by increasing inflammatory and anti-inflammatory cytokines production, while the effect of Protec and Chizukit N is much less. Sambucol could therefore have immunostimulatory properties when administered to patients suffering from influenza (as shown before), or immunodepressed cancer or AIDS patients who are receiving chemotherapy or other treatments.