Study on the effect of a triple cancer treatment of propolis, thermal cycling-hyperthermia, and low-intensity ultrasound on PANC-1 cells

To reduce side effects and enhance treatment efficacy, study on combination therapy for pancreatic cancer, a deadly cancer, has gained much attraction in recent years. In this study, we propose a novel triple treatment combining propolis and two physical stimuli-thermal cycling-hyperthermia (TC-HT) and low-intensity ultrasound (US). The study found that, after the triple treatment, the cell viability of a human cancer cell line PANC-1 decreased to a level 80% less than the control, without affecting the normal pancreatic cells. Another result was excessive accumulation of reactive oxygen species (ROS) after the triple treatment, leading to the amplification of apoptotic pathway through the MAPK family and mitochondrial dysfunction. This study, to the best of our knowledge, is the first attempt to combine TC-HT, US, and a natural compound in cancer treatment. The combination of TC-HT and US also promotes the anticancer effect of the heat-sensitive chemotherapy drug cisplatin on PANC-1 cells. It is expected that optimized parameters for different agents and different types of cancer will expand the methodology on oncological therapy in a safe manner.

Therapeutic efficacy of caffeic acid phenethyl ester in cancer therapy: An updated review

Nowadays, there is a lot of public and scientific interest in using phytochemicals to treat human ailments. Existing cancer medicines still run across obstacles, despite significant advancements in the field. For instance, chemotherapy may result in severe adverse effects, increased drug resistance, and treatment failure. Natural substances that are phytochemically derived provide innovative approaches as potent therapeutic molecules for the treatment of cancer. Bioactive natural compounds may enhance chemotherapy for cancer by increasing the sensitivity of cancer cells to medicines. Propolis has been found to interfere with the viability of cancer cells, among other phytochemicals. Of all the components that make up propolis, caffeic acid phenethyl ester (CAPE) (a flavonoid) has been the subject of the most research. It demonstrates a broad spectrum of therapeutic uses, including antitumor, antimicrobial, antiviral, anti-inflammatory, immunomodulatory, hepatoprotective, neuroprotective, and cardioprotective effects. Studies conducted in vitro and in vivo have demonstrated that CAPE specifically targets genes involved in cell death, cell cycle regulation, angiogenesis, and metastasis. By altering specific signaling cascades, such as the NF-κB signaling pathway, CAPE can limit the proliferation of human cancer cells. This review highlights the research findings demonstrating the anticancer potential of CAPE with a focus on multitargeted molecular and biological implications in various cancer models.

Effects of propolis-loaded nanoliposomes fortification in extender on buffalo semen cryopreservation

Buffalo sperm is sensitive to cryoinjuries, thus improving sperm cryoresistance is a critical approach for wide spreading the assisted reproductive technologies in buffalo. The intention of this work was to assess the effect of propolis-loaded in nanoliposomes (PRNL) supplementation of semen extender on semen quality, antioxidant status and some apoptotic genes of cryopreserved buffalo semen. PRNL were prepared using cholesterol (Chol) as well as soybean lecithin and their physicochemical properties were characterized. Egyptian buffalo bulls (4-6 years) were involved, and the semen samples were collected using the artificial vagina method. Buffalo semen was pooled (n = 25 ejaculates) and cryopreserved in tris extender containing PRNL at 0 (PRNL0), 2 (PRNL2), 4 (PRNL4) and 6 µg/mL (PRNL6), respectively. The PRNL had a size of 113.13 nm and a negative zeta potential (- 56.83 mV). Sperm progressive motility, viability, membrane integrity, abnormalities, chromatin damage, redox status, apoptosis status, and apoptotic genes were investigated after post-thawed buffalo semen. Using 2 or 4 µg/mL PRNL significantly increased sperm progressive motility, viability, and membrane integrity, while sperm abnormalities and the percentage of chromatin damages were the lowest in PRNL2 group. Moreover, the PRNL2 group exhibited the best results for all antioxidative activities (TAC, SOD, GPx and CAT) with significantly higher levels than the other groups (P < 0.05). The levels of ROS and MDA were significantly lower in the PRLN2 compared with other groups. The sperm caspase 3 enzyme activities showed the lowest values in PRNL2 groups followed by PRNL4 and PRNL6 groups with significant differences compared with the control. Adding 2 µg/mL PRNL to freezing media significantly reduced apoptotic genes such as Bax and Caspase 3 in sperm, while significantly increase in Bcl2 expression compared with the control (P < 0.001). The expression of Bcl2, Caspase 3 and Bax genes in sperm were not affected by the 6 µg/mL PRNL addition (P > 0.05). The electron micrography descriptions exemplified that the fortification of 2 or 4 µg/mL PRNL maintained the acrosomal and plasma membrane integrities as well as sustained the ultrastructure integrity of the cryopreserved buffalo spermatozoa when compared with control group, whereas the 6 µg/mL of PRNL demonstrated highest injury to the acrosome and plasma membranes. Results show supplementation of the buffalo freezing extender with 2 or 4 µg/mL of PRNL enhanced post-thawed sperm quality via boosting the antioxidant indices, diminishing the oxidative stress and apoptosis as well as maintained the ultrastructure integrity of frozen-thawed buffalo sperm.

Ethanol extract of propolis regulates type 2 diabetes in mice via metabolism and gut microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis is a traditional natural medicine with various activities such as antioxidant and anti-inflammatory, immunomodulatory, anti-tumour, gastroenteritis treatment and prevention, anti-microbial and parasitic, as well as glucose regulation and anti-diabetes, and is expected to be an anti-diabetic candidate with few side effects, but the mechanism of action of propolis on type 2 diabetes mellitus (T2DM) has not been fully elucidated.

AIM OF THE STUDY

The purpose of this study was to investigate the mechanism of the effect of ethanol extract of propolis (EEP) on the regulation of blood glucose in T2DM mice.

MATERIALS AND METHODS

We studied the possible mechanism of EEP on T2DM using an animal model of T2DM induced by a combination of a high-fat diet and intraperitoneal injection of streptozotocin (STZ). The experiment was divided into four groups, namely, the normal group (HC), model group (T2DM), EEP and metformin group (MET). Biochemical indexes and cytokines were measured, and the differences of metabolites in the serum were compared by ¹H-NMR. In addition, the diversity of intestinal flora in feces was studied by 16S rDNA amplicon sequencing.

RESULTS

The results showed that following treatment with EEP and MET, the weight-loss trend of mice was alleviated, and the fasting blood glucose, insulin secretion level, insulin resistance index, C peptide level and oral glucose tolerance level decreased, whereas the insulin sensitivity index increased, thereby EEP effectively alleviated the occurrence of T2DM and insulin resistance. Compared with the T2DM group, the concentrations of pro-inflammatory cytokines interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) decreased significantly in EEP and MET groups, whereas the concentrations of anti-inflammatory cytokine interleukin-10 (IL-10) increased significantly. Metabolomics results revealed that EEP and MET regulate carbohydrate metabolism and restore amino acid and lipid metabolism. Correlation analysis of intestinal flora in mouse feces showed that compared with the HC group, harmful bacteria such as Bilophila, Eubacterium_ventriosum_group, Mucispirillum and Desulfovibrio were found in the T2DM group, whereas the abundance of beneficial bacteria such as Lactobacillus was significantly reduced. Parabacteroides, Akkermansia, Leuconostoc, and Alloprevotella were abundantly present in the EEP group; however, the MET group showed an increase in the genus Parasutterella, which could regulate energy metabolism and insulin sensitivity.

CONCLUSIONS

The results showed that EEP and MET reduce fasting blood glucose in T2DM mice, followed by alleviating insulin resistance, improving the inflammatory reaction of mice, regulating the metabolism of mice, and affecting the steady state of gut microbiota. However, the overall therapeutic effect of EEP is better than that of MET.

Anti-Bacterial Activity of Four Distinct Propolis Extracts against P. larvae and M. plutonius; Etiological Agent of American and European Foulbrood Disease of Honeybees

Four different propolis samples obtained from different regions of Iran were evaluated for their antibacterial effects against the bacterial agents responsible for two important honeybee diseases. Paenibacillus larvae (P. larvae) and Melissococcus plutonius (M. plutonius), as the etiological agents of American foulbrood (AFB) and European foulbrood (EFB) diseases, were subjected to propolis ethanolic extracts in the agar well diffusion assay. The minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC) of the antibacterial effects of the samples against the two indicator organisms were determined by the microdilution technique using different concentrations of the propolis extracts. Finally, the synergistic antibacterial actions of the mixed propolis samples were determined, and their MIC and MBC values were recorded. A two-way analysis of variance was used to evaluate correlations among the diameters of the inhibition zones, the bacterial agents, and the propolis extracts. Based on our results, three of the propolis samples showed significant antibacterial effects against P. larvae and M. plutonius during the agar well diffusion assay. Furthermore, the antibacterial capacity of the propolis samples, when mixed in equal proportions, was significantly enhanced, as indicated by the obtained MIC and MBC values. Approximately, 0.02 mg/mL of mixed propolis samples was required for inhibiting the growth of both pathogens. A direct correlation was observed between propolis concentrations and their antibacterial activity. The results of the study are conclusive of the significant antibacterial actions of Iranian propolis samples against the etiological agents of the mentioned honeybee diseases, suggesting their probable use as a safe biological agent to control AFB and EFB diseases.

Evaluation of antibacterial effects of different intracanal medicaments on Enterococcus faecalis in primary teeth: An in vitro study

OBJECTIVES

Successful endodontic therapy is based on the reduction of infecting bacteria by cleaning, shaping, and disinfecting of the root canal system, thus the use of intracanal dressing is necessary for optimal success of root canal treatment. This study was designed to evaluate the effect of chitosan and propolis as intracanal medicaments against Enterococcus faecalis compared to calcium hydroxide in primary root canals.

MATERIAL AND METHODS

Ninety-six extracted primary second molars were collected. Teeth preparation was completed to size 30 K-file. They were randomly divided into four groups; (A): chitosan, (B): propolis, (C): calcium hydroxide, and (D): control group (saline). The tooth specimens were inoculated with E. faecalis. Then, tested materials were applied for all groups in accordance to the groups each tooth belonged to. Following this, the bacterial colonies were counted after 24 h, 72 h, and 1 week of applying dressing materials and incubation. Finally, one-way analysis of variance and Fisher's least significant difference tests were used for statistical comparisons between the groups at a significance level of .05.

RESULTS

No statistically significant difference was found between groups A, B, and C for both 24 h and a week (p ≥ .05). Yet, a statistical difference between groups A, B, C, and D after 72 h and 1 week were seen (p ≤ .05).

CONCLUSIONS

Chitosan and propolis medicaments were as effective as calcium hydroxide against E. faecalis in primary root canal treatment and might be considered as an alternative dressing material between treatment sessions.

Phenolic Compounds Contribution to Portuguese Propolis Anti-Melanoma Activity

Melanoma is the deadliest type of skin cancer, with about 61,000 deaths annually worldwide. Late diagnosis increases mortality rates due to melanoma’s capacity to metastasise rapidly and patients’ resistance to the available conventional therapies. Consequently, the interest in natural products as a strategy for drug discovery has been emerging. Propolis, a natural product produced by bees, has several biological properties, including anticancer effects. Propolis from Gerês is one of the most studied Portuguese propolis. Our group has previously demonstrated that an ethanol extract of Gerês propolis collected in 2018 (G18.EE) and its fractions (n-hexane, ethyl acetate, and n-butanol) decrease melanoma cell viability. Out of all the fractions, G18.EE-n-BuOH showed the highest potential as a melanoma pharmacological therapy. Thus, in this work, G18.EE-n-BuOH was fractioned into 17 subfractions whose effect was evaluated in A375 BRAF-mutated melanoma cells. The subfractions with the highest cytotoxic activity were analysed by UPLC-DAD-ESI/MSn in an attempt to understand which phenolic compounds could account for the anti-melanoma activity. The compounds identified are typical of the Gerês propolis, and some of them have already been linked with antitumor effectiveness. These results reaffirm that propolis compounds can be a source of new drugs and the isolation of compounds could allow its use in traditional medicine.

Propolis Ethanolic Extract Attenuates D-gal-induced C2C12 Cell Injury by Modulating Nrf2/HO-1 and p38/p53 Signaling Pathways

Previous study has shown that propolis ethanolic extract (PEE) has a protective effect on aging skeletal muscle atrophy. However, the exact molecular mechanism remains unclear. This study aimed to investigate the effect of PEE on D-galactose (D-gal)-induced damage in mouse C2C12 cells. The results revealed that PEE increased the viability of senescent C2C12 cells, decreased the number of senescence-associated β-galactosidase (SA-β-Gal)-positive cells and promoted the differentiation of C2C12 cells. PEE resisted oxidative stress caused by D-gal by activating the Nrf2/HO-1 signaling pathway and maintained the differentiation ability of C2C12 cells. PEE inhibited apoptosis by suppressing p38 phosphorylation and reducing p53 expression. In summary, our findings reveal the molecular mechanism by which PEE protects D-gal-induced C2C12 cells, providing a theoretical basis for the development of PEE for the alleviation of muscle atrophy.

Effect of propolis on mood, quality of life, and metabolic profiles in subjects with metabolic syndrome: a randomized clinical trial

Metabolic syndrome (MeS) is a common multifaceted disorder. Plants contain antioxidant bioactive compounds, which are beneficial to improve the health condition of patients with MeS. Propolis is a hive natural product that is composed of various constituent. We aimed to assess the effects of Iranian propolis as a natural and safe agent on indicators of MeS, quality of life and mood status in individuals with MeS. In total, 66 interested eligible patients recruited to the present study. Participants were randomly assigned to consume a tablet at dose of 250 mg of propolis extract, twice daily for 12 weeks or placebo. Propolis supplementation could lead to a significant reduction in waist circumference (WC), increase in physical functioning, general health and the overall score of SF-36 compared with placebo group (P-value < 0.05). However, no significant differences were observed regarding other anthropometric indices and biochemical parameters between two groups (P-value > 0.05). The current study indicated that propolis can be effective in decreasing WC and improving physical health and quality of life, while had no significant effects on other components of MeS among subjects with this syndrome. Clinical trials registration Iran Registry of Clinical Trials.ir IRCT20121216011763N49, registration date 23/12/2020.

Anti-Inflammatory, Antimicrobial, Antioxidant and Photoprotective Investigation of Red Propolis Extract as Sunscreen Formulation in Polawax Cream

Many activities have been described for propolis, including, antiviral, antibacterial, antifungal, anti-inflammatory, immunoregulatory, antioxidant and wound healing properties. Recently, propolis has been highlighted due to its potential application in the pharmaceutical and cosmetic industries, motivating a better understanding of its antioxidant and anti-inflammatory activities. Propolis and its main polyphenolic compounds presented high antioxidant activity, and effectiveness as broad spectrum UVB and UVA photoprotection sunscreens. Through a qualitative phytochemical screening, the ethanolic red propolis extracts (EEPV) (70% at room temperature and 70% at a hot temperature) presented a positive result for flavonoids and terpenoids. It presented an antioxidant activity for reducing 50% of DPPH of 17 and 12 μg/mL for extraction at room temperature and at a hot temperature, respectively. The UPLC-QTOF-MS/MS analysis allowed the annotation of 40 substances for EEPV-Heated and 42 substances for EEPV-Room Temperature. The IC50 results of the ABTS scavenging activity was 4.7 μg/mL for both extractions, at room temperature and at a hot temperature. Additionally, we also evaluated the cytotoxic profile of propolis extracts against macrophage (RAW 264.7 cells) and keratinocytes (HaCaT cells), which showed non-cytotoxic doses in cell viability assays even after a long period of exposure. In addition, propolis extracts showed antibacterial activity for Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), demonstrating potential biological activity for the creation of formulations aimed at disease control and prevention.

The benefits of propolis in periodontal therapy. A scoping review of preclinical and clinical studies

ETHNOPHARMACOLOGICAL RELEVANCE

The treatment of periodontal disease (PD) is aimed at adequate control of bacterial plaque. In many patients mechanical methods are unable to eliminate this plaque leading to the need for adjuvant chemical products. Propolis is a natural product that has demonstrated therapeutic properties and has shown to be effective as an anti-inflammatory and antibacterial agent in dentistry.

AIM OF THE STUDY

Considering the beneficial effects of propolis on various oral conditions, this study aimed to review, update and summarize the available evidence on the benefits of propolis in in vitro studies, animal models, and human clinical trials on non-surgical periodontal therapy.

MATERIALS AND METHODS

An electronic search in three databases was performed up to December 2021. The search strategy included the terms "propolis" and "periodontal disease" to identify relevant studies on the potential advantages of propolis in periodontal therapy in in vitro studies, animal models, and human clinical trials.

RESULTS

The search yielded 538 results, discarding 459 studies that did not clearly meet the inclusion criteria. A total of 42 studies were included: 18 in vitro, one animal, and 23 randomized clinical trials. In vitro studies have demonstrated that propolis has antimicrobial activity against periodontal pathogens and clinical studies have reported its use as an adjunct to non-surgical periodontal therapy. The clinical effects of propolis have been reported in conjunction with prophylaxis, polishing, and scaling and root planing (SRP). It has shown to have anti-plaque activity and improve gingival health. Propolis was found to be more effective in improving clinical parameters than conventional treatment (SRP alone) and demonstrated similar efficacy in treating chronic periodontitis compared to positive controls. Only one study reported an allergic reaction.

CONCLUSION

The evidence available on the benefits of propolis in in vitro studies, animal models, and clinical trials suggests that propolis could be a promising adjunct to conventional therapy of gingivitis and periodontitis. However, further studies are needed to determine its superiority to other therapies in the treatment of PD.

A Systematic Review of the Potential Effects of Propolis Extracts on Experimentally-induced Diabetes

Oxidative stress (OS) is involved in the development of diabetes mellitus (DM) and its complications. Thus, OS reduction may be an important strategy for DM therapy. Propolis is bee resins with high antioxidant activity and is used in the treatment of different diseases, including DM. Therefore, in this systematic review, we evaluated the impact of propolis administration in diabetic animals. We used the PRISMA strategy to collect preclinical studies published in English up to November 2021 in three databases (PubMed/Medline, Scopus, and Web of Science). We used the SYRCLE tool to analyze the risk of methodological bias. Our primary search returned 198 studies, of which 14 were considered eligible to be included in this review. The administration of propolis induced a hypoglycemic effect in the treated animals, which is probably due to the reduction of OS. The animals showed restoration of endogenous antioxidant defenses and reduced levels of markers for OS. The administration of propolis resulted in improvement in the lipid profile of treated animals. Our risk of bias assessment showed a methodological quality score of less than 30% due to a lack of randomization, blinding, and proper allocation of animals. Heterogeneity in treatments, lack of results, and use of non-standard extracts are limitations in our data analysis. Despite these limitations, propolis induced a significant hypoglycemic effect in diabetic animals when compared to untreated controls. This effect was associated with a reduction in OS, a process mediated by ROS neutralization and restoration of endogenous antioxidant defenses.

Chemical Characterization and Antimicrobial Properties of the Hydroalcoholic Solution of Echinacea purpurea (L.) Moench. and Propolis from Northern Italy

In this study, for the first time, the chemical composition of Echinacea purpurea (L.) Moench. and propolis (EAP) hydroalcoholic solution from the Trentino Alto Adige region of northern Italy was investigated by using SPME-GC-MS to describe the volatile content and GC-MS after silylation to detect the non-volatile compounds in the extractable organic matter. The antimicrobial activity of EAP hydroalcoholic solution was evaluated by Minimum Inhibitory Concentration (MIC) determination on 13 type strains, food and clinical isolates. Time Kill Kinetics (TKK) assays and the determination on swimming and swarming motility for 48 h gave more details on the mode of action of EAP solution. The results highlighted the presence of some terpenes and a large number of compounds belonging to different chemical classes. Among these, sugars and organic acids excelled. The EAP hydroalcoholic solution exhibited a strong antimicrobial activity in terms of MIC, with a clear decrease in the cellular load after 48 h. However, the bacterial motility may not be affected by the EAP treatment, displaying a dynamic swarming and swimming motility capacity over time. Given the complexity of chemical profile and the strong antimicrobial effectiveness, the EAP hydroalcoholic solution can be considered a source of bioactive molecules, deserving further investigation for the versatility of application.

Effects of propolis on inflammation markers in patients undergoing hemodialysis: A randomized, double-blind controlled clinical trial

BACKGROUND AND AIMS

Several studies have been performed in vitro and in animals showing that propolis (a resin made by bees) has excellent anti-inflammatory properties, but no study has been performed in patients with chronic kidney disease (CKD) on hemodialysis (HD). The present study aimed to evaluate the effects of propolis supplementation on inflammatory markers in patients with CKD on HD.

METHODS

This is a longitudinal, double-blind, placebo-controlled trial with patients randomized into two groups: propolis (4 capsules of 100 mg/day containing concentrated and standardized dry EPP-AF® green propolis extract) or placebo (4 capsules of 100 mg/day containing microcrystalline cellulose, magnesium stearate and colloidal silicon dioxide) for two months. Routine parameters were analyzed using commercial kits. The plasma levels of inflammatory cytokines were evaluated by flow luminometry.

RESULTS

Forty-one patients completed the follow-up, 21 patients in the propolis group (45 ± 12 years, 13 women, BMI, 22.8 ± 3.7 kg/m²) and 20 in the placebo group (45.5 ± 14 years, 13 women, BMI, 24.8 ± 6.8 kg/m²). The obtained data revealed that the intervention with propolis significantly reduced the serum levels of tumour necrosis factor α (TNFα) (p = 0.009) as well as had the tendency to reduce the levels of macrophage inflammatory protein-1β (MIP-1β) (p = 0.07). There were no significant differences in the placebo group.

CONCLUSION

Short-term EPP-AF® propolis dry extract 400 mg/day supplementation seems to mitigate inflammation, reducing the plasma levels of TNFα and MIP-1β in patients with CKD on HD. This study was registered at clinicaltrials.gov (NCT04411758).

Brazilian Propolis Intake Decreases Body Fat Mass and Oxidative Stress in Community-Dwelling Elderly Females: A Randomized Placebo-Controlled Trial

This study aimed to investigate the effects of Brazilian propolis on body fat mass and levels of adiponectin and reactive oxygen species among community-dwelling elderly females. This was a double-blind randomized placebo-controlled trial. Altogether, 78 females aged 66-84 years were randomly assigned to the propolis (PRO; n = 39) or placebo (PLA; n = 39) group. For 12 weeks, the PRO group were given three capsules containing 227 mg of propolis twice a day. Meanwhile, the PLA group were given daily placebo capsules. Of 78 participants, 53 (PLA group: n = 28, PRO group: n = 25) completed the study. Although no changes were observed in absolute or relative fat mass in the PLA group, they showed a significant decline in the PRO group. The level of serum adiponectin in the PLA group did not change, although that of the PRO group significantly increased. The level of d-ROMs in the PLA group significantly increased, whereas that of the PRO group significantly decreased. The serum SOD activity in the PLA group significantly decreased, whereas that of the PRO group tended to increase. These results suggest that propolis supplementation may decrease body fat mass and oxidative stress among community-dwelling elderly females.

Ameliorative Effects of Propolis and Royal Jelly against CCl4 -Induced Hepatotoxicity and Nephrotoxicity in Wistar Rats

Carbon tetrachloride (CCl₄ ) is known to have hepatotoxic and nephrotoxic effects. During the two-month CCl₄ exposure of Wistar rats, propolis extract (PE) and royal jelly (RJ) were added in order to test the potential protective effect against hepato-renal injury. Ketonuria, proteinuria, high creatinine and urea levels are the result of CCl₄ -induced nephrotoxicity. Severe disorders of hematological indicators indicate anemia; high values of leukocytes indicate inflammatory condition. Cytogenetic impairments in hepatocytes, aggregation of platelets, and hypoproteinemia indicate severe liver impairment. Results suggest a more significant protective role of RJ compared to PE. Both extracts regulated proteinuria, ketonuria, hypoproteinemia and reduced platelet aggregation in the hepatic circulation. The increase in the number of erythrocytes (RBC) suggest protective effects against anemia; the decrease in the number of leukocytes can be linked to anti-inflammatory effects. PE and RJ have a beneficial effect against hepato-renal injury, anemia and anti-inflammatory conditions caused by CCl₄ .

Propolis: Antineoplastic Activity, Constituents, and Mechanisms of Action

Propolis is a beehive product with great pharmacological potential, including antineoplastic activity.

OBJECTIVES

The aim of this study is to provide an actual understanding of the existent scientific information regarding the antiproliferative effect of propolis, proposed mechanisms of action, and challenges to meet.

METHODS

An assessment of the scientific literature was attained using the PubMed and SciFinder platforms. Research papers, clinical trials, and reviews published between the years 2000 - 2021, were considered. The words "anticancer", "antitumor", "antiproliferative" and "propolis" were used in the search criteria.

CONCLUSION

A summary of several antiproliferative activities of different types of propolis is exposed. The potential health benefits of propolis are discussed. The variable plant origin of propolis partially accounts for its anti-cancer activities. Even when some mechanisms of action of propolis have been proposed, much of the genesis of how this effect is produced is yet to be answered, including several molecular mechanisms in different biological systems.

Caffeic acid phenethyl ester suppresses intestinal FXR signaling and ameliorates nonalcoholic fatty liver disease by inhibiting bacterial bile salt hydrolase activity

Propolis is commonly used in traditional Chinese medicine. Studies have demonstrated the therapeutic effects of propolis extracts and its major bioactive compound caffeic acid phenethyl ester (CAPE) on obesity and diabetes. Herein, CAPE was found to have pharmacological activity against nonalcoholic fatty liver disease (NAFLD) in diet-induced obese mice. CAPE, previously reported as an inhibitor of bacterial bile salt hydrolase (BSH), inhibited BSH enzymatic activity in the gut microbiota when administered to mice. Upon BSH inhibition by CAPE, levels of tauro-β-muricholic acid were increased in the intestine and selectively suppressed intestinal farnesoid X receptor (FXR) signaling. This resulted in lowering of the ceramides in the intestine that resulted from increased diet-induced obesity. Elevated intestinal ceramides are transported to the liver where they promoted fat production. Lowering FXR signaling was also accompanied by increased GLP-1 secretion. In support of this pathway, the therapeutic effects of CAPE on NAFLD were absent in intestinal FXR-deficient mice, and supplementation of mice with C16-ceramide significantly exacerbated hepatic steatosis. Treatment of mice with an antibiotic cocktail to deplete BSH-producing bacteria also abrogated the therapeutic activity of CAPE against NAFLD. These findings demonstrate that CAPE ameliorates obesity-related steatosis at least partly through the gut microbiota-bile acid-FXR pathway via inhibiting bacterial BSH activity and suggests that propolis enriched with CAPE might serve as a promising therapeutic agent for the treatment of NAFLD.

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.

Protective Effect of Thyme and Chestnut Honeys Enriched with Bee Products against Benzo(a)pyrene-Induced DNA Damage

The aim of the present study was to validate the cytotoxicity, genotoxicity, and preventive potential against benzo(a)pyrene (BaP)-induced DNA damage of nine samples of thyme and chestnut honeys enriched with bee products (royal jelly and propolis, 2-10%). Cell viability was determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay (0-250 mg/mL) to select nontoxic concentrations, and DNA damage (0.1-10 μg/mL) was evaluated by the alkaline single-cell gel electrophoresis or comet assay. Treatment with honey samples or royal jelly and propolis did not affect the viability of HepG2 cells up to 100 and 50 mg/mL, respectively. Treatment with 100 μM BaP significantly increased (p ≤ 0.001) the levels of the DNA strand breaks. None of the tested concentrations (0.1-10 μg/mL) of the honey samples (thyme and chestnut), royal jelly, and propolis caused DNA damage per se. All tested samples at all the concentrations used decreased the genotoxic effect of BaP. In addition, all mixtures of thyme or chestnut honeys with royal jelly or propolis showed a greater protective effect against BaP than the samples alone, being the thyme and chestnut honey samples enriched with 10% royal jelly and 10% propolis the most effective (70.4% and 69.4%, respectively). The observed protective effect may be associated with the phenolic content and antioxidant capacity of the studied samples. In conclusion, the thyme and chestnut honey samples enriched with bee products present potential as natural chemoprotective agents against the chemical carcinogen BaP.

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.

Effect of Propolis on Precocious Puberty in Female Rats

Objective

Nutrition and exposure to various chemicals, including environmental pollution, insecticides, and plant phytoestrogens (having oestrogen-like effects), are environmental factors that affect puberty onset. The aim of this study was to identify the effects of propolis, which has been reported to have oestrogenic effects, on precocious puberty and the reproductive system in prepubertal female rats (ovary, endometrium, breast).

Methods

Thirty-four 25-day-old, prepubertal, female Sprague-Dawley rats were included. Rats were randomly divided into the propolis (n=17) and control groups (n=17). The primary endpoint was the number of rats that developed vaginal opening, a sign of puberty, at 12-day follow-up. In addition, the effect of propolis on ovary, uterus and breast tissue was evaluated histologically.

Results

Vaginal patency occurred earlier (about 7.5 days sooner) in the propolis group and all animals in the propolis group had vaginal patency by day 12. The number of ovarian follicles (in all follicles), endometrial thickness, and mammary gland secretory gland area were significantly higher in the propolis group than in the control group (all p<0.001). In addition, Ki-67 activity in the endometrium, breast tissue and ovary was more intense in the propolis group compared to the control group (all p<0.001).

Conclusion

Propolis triggers precocious puberty in female rats, possibly by interacting with the oestrogen receptor. The mechanism of action of propolis should be considered before prescribing it. In addition, further studies are needed to explore the mechanism of action of propolis and to determine the component of propolis that triggers puberty.

Antimicrobial and Antibiofilm Effect of Brazilian Green Propolis Aqueous Extract against Dental Anaerobic Bacteria

Green propolis may represent a promising therapeutic alternative against dental anaerobic pathogens because of its antimicrobial action. This study aimed to evaluate the antimicrobial and antibiofilm actions of Brazilian green propolis aqueous extract (BGP-AqExt) against dental anaerobic bacteria. The minimum inhibitory concentration (MIC) and minimum microbicide concentration (MMC) of the extract were determined against the standard strains (ATCC) of Fusobacterium nucleatum, Parvimonas micra, Prevotella intermedia, Porphyromonas gingivalis and Porphyromonas endodontalis. BGP-AqExt was chemically characterized by high-performance liquid chromatography with diode-array detection (HPLC-DAD) analysis. Antibiofilm action was measured by MTT and crystal violet tests. The data were statistically analyzed by ANOVA and Tukey (5%) tests. The extract had antimicrobial action against all tested anaerobic bacteria, with an MIC value of 55 mg/mL for all bacteria, an MMC of 27.5 mg/mL for F. nucleatum and P. micra and 55 mg/mL for P. intermedia. Chemically, BGP-AqExt is composed of quercetin, gallic acid, caffeic and p-coumaric acid, drupani, kaempferol and Artepillin C. Significant reductions in biomass and metabolic action of biofilms were found after BGP-AqExt application. Therefore, BGP-AqExt has an antimicrobial and antibiofilm effect against dental anaerobic bacteria.

Propolis Efficacy: The Quest for Eco-Friendly Solvents

Propolis, a natural product made by bees with resins and balsams, is known for its complex chemical composition and remarkable bioactivities. In this study, propolis extraction was studied seeking extracts with strong bioactivities using less orthodox solvents, with some derived from apiary products. For that, a propolis sample collected from Gerês apiary in 2018 (G18) was extracted by maceration with six different solvents: absolute ethanol, ethanol/water (7:3), honey brandy, mead, propylene glycol and water. The solvent influence on the chemical composition and antioxidant and antimicrobial activities of the extracts was investigated. Antioxidant potential was assessed by the DPPH free-radical-scavenging assay and the antimicrobial activity by the agar dilution method. Chemical composition of the extracts was determined in vitro by three colorimetric assays: total ortho-diphenols, phenolics and flavonoids contents and the LC-MS technique. To our knowledge, this is the first time that solvents such as honey brandy and mead have been studied. Honey brandy showed considerable potential to extract propolis active compounds able to inhibit the growth of bacteria such as the methicillin-sensitive Staphylococcus aureus and Propionibacterium acnes (MIC values of 100 and 200 µg/mL, respectively) and the fungi Candida albicans and Saccharomyces cerevisiae (MIC = 500 µg/mL, for both). Mead extracts displayed high antioxidant capacity (EC50 = 1.63 ± 0.27 µg/mL) and great activity against resistant bacteria such as the methicillin-resistant Staphylococcus aureus and Escherichia coli (MIC = 750 µg/mL, for both). The production of such solvents made from beehive products further promotes a diversification of apiary products and the exploration of new applications using eco-friendly solutions.

Anti-Inflammatory Effect of Korean Propolis on Helicobacter pylori-Infected Gastric Mucosal Injury Mice Model

Propolis, a natural resinous substance obtained from a variety of buds and plants, has been reported to possess various biological functions. Several recent studies have demonstrated the inhibitory effects of propolis on the growth of Helicobacter pylori (H. pylori) in vitro; however, current research efforts on Korean propolis (KP) remain insufficient especially in vivo. Our study aims to investigate the anti-inflammatory effect and molecular mechanism of KP on mouse gastric mucosa during H. pylori infection. We examined an in vivo H. pylori-induced gastric mucosal injury mice model. We found that KP inhibited the growth of H. pylori and attenuated the expression of H. pylori virulence factors such as cytotoxin-associated gene A, encoding urease A subunit, surface antigen gene and neutrophil-activating protein A. Moreover, KP reduced both gross lesions and pathological scores in H. pylori-challenged mice. In addition, KP markedly restrained the production of pro-inflammatory cytokines and nitric oxide levels compared with an untreated H. pylori-infected group. In particular, we found that KP repressed the phosphorylation of IκBα and NF-κB p65 subunit, and subsequently suppressed their downstream target genes. Taken together, these findings demonstrate the beneficial effects of KP on inflammation through the inhibition of NF-κB signaling as well as inhibition of H. pylori growth in a mouse model infected with H. pylori. This suggests the potential application of KP as a natural supplement for patient’s suffering from gastric mucosal injury caused by H. pylori infection.