Antitumor Activity of Chinese Propolis in Human Breast Cancer MCF-7 and MDA-MB-231 Cells

Propolis Stands out as a Multifaceted Natural Product: Meta-Analysis on Its Sources, Bioactivities, Applications, and Future Perspectives

Honeybee (Apis spp.) products have been used for centuries due to their nutritional value and diverse healing properties. Propolis, produced by honeybees, is a unique resin collected from tree buds, sap flows, and other plant exudates, which is then mixed with bee enzymes, beewax, and secretions. This comprehensive review starts with a meta-analysis following the PRISMA approach to explore recent advances in the chemical composition of propolis, its biological activities and pharmacological properties, its applications and products, and future perspectives. The composition of propolis varies depending on plant source, season of harvest, geography, type of bee flora, climate, and honeybee species at the site of collection, and some of these are related. Flavonoids, aromatic acids, phenolic acids, and their esters are key bioactive compounds in propolis, contributing to their diverse pharmacological properties, such as antioxidant, antibacterial, antiparasitic, antiviral, antileishmanial, antidiabetic, anti-inflammatory, immunomodulatory, and anticancer effects. In summary, propolis stands out as a multifaceted natural product with a broad spectrum of biological activities. This review aims to provide valuable insights for researchers, practitioners, and decision-makers involved in studying the sources, composition, and biological activities of propolis. The highlighted hotspots and emerging frontiers presented herein are poised to unlock the full potential of propolis, paving the way for innovative applications in health and wellness.

Propolis mouthwashes efficacy in managing gingivitis and periodontitis: a systematic review of the latest findings

BACKGROUND AND OBJECTIVES

Gingivitis and periodontitis are common periodontal diseases that can significantly harm overall oral health, affecting the teeth and their supporting tissues, along with the surrounding anatomical structures, and if left untreated, leading to the total destruction of the alveolar bone and the connective tissues, tooth loss, and other more serious systemic health issues. Numerous studies have shown that propolis can help reduce gum inflammation, inhibit the growth of pathogenic bacteria, and promote tissue regeneration, but with varying degrees of success reported. For this reason, this comprehensive systematic review aims at finding out the truth concerning the efficacy of propolis mouthwashes in treating gingivitis and periodontitis, as its main objective.

DATA SOURCES

Research findings from 6 different databases: China National Knowledge Infrastructure (CNKI), PubMed®, Europe PMC, Cochrane Central Register of Controlled Trials (CENTRAL), BioMed Central, and Google Scholar, were retrieved and examined in addition to a manual search in the references lists.

STUDY SELECTION AND SYNTHESIS

The PICOS framework was used to select and exclude studies. The focus was on clinical randomized controlled trials (RCTs) that examined the effectiveness of propolis-containing mouthwashes in comparison with propolis-free ones for the treatment of gingivitis and periodontitis, employing related periodontal indices. Animal studies, microbiological studies, in-vitro studies, retrospective studies, case-control studies, cohorts, case reports, case series, reviews, letters, editorials, meta-analyses, and non-clinical randomized controlled trials (non-RCTs), all were excluded. A meta-analysis was not performed and data were only studied qualitatively due to the obvious heterogeneity amongst the studies. Data from the selected studies were extracted, and then the revised Cochrane's risk of bias tool (RoB 2.0) was utilised by two of the authors, independently, to evaluate the risk of bias in each study.

RESULTS

At first, 151 results were reached, but then after removing duplicates, 99 records remained, and were later screened, assessed, and studied in full details based on the set PICOS criteria. Out of these 99 articles, ten studies were included in this systematic review, encompassing a total of 453 patients with an age range of (13-70) years old. Propolis mouthwashes with different protocols of application were the intervention whereas placebo or the rest of the tested mouthwashes such as, chlorhexidine, sodium fluoride with cetylpyridinium chloride, sterile distilled water, hydrogen peroxide, were the ones to which propolis mouthwashes were compared. Treatment duration extended from 14 days to 3 months and the follow-up period differed from 14 days to 3 months. In general, propolis mouthwashes decreased plaque accumulations and gingival inflammation in gingivitis patients based on the employed indices. On the other hand, the aforementioned tested mouthwashes other than propolis were deemed equally effective or even superior to propolis in some studies. As an overall assessment for the risk of bias, four studies were assigned as having a low risk of bias. Two studies were deemed to have some concerns, while four studies were identified as having a high risk of bias.

CONCLUSIONS

Despite the fact that propolis has shown positive effects in terms of controlling gingival and periodontal inflammation especially when used with mechanical methods, studies lack certainty and their power of evidence is low with no agreed gold standards. These conclusions come, for sure, within the limitations of this review, like having substantial variability amongst the included studies and the presence of studies with a high risk of bias. The findings demonstrate that propolis-based mouthwashes showed promising clinical outcomes in reducing plaque and gingival inflammation. However, it is highly recommended to conduct more rigorous trials with patient-reported outcome measures, extended follow-up periods, larger samples sizes, better-designed methodologies, typified propolis use, and with the implementation of similar indices in order to obtain more reliable, conclusive, and generalisable results.

PROSPERO REGISTRATION NUMBER

CRD42024524523.

Wolfberry Honey and Its Extract Alleviate Dextran Sodium Sulfate-Induced Ulcerative Colitis by Improving Intestinal Barrier Function and Reducing Oxidative Stress and Inflammation

Inflammatory bowel disease (IBD) is a chronic condition characterized by gut inflammation causing persistent diarrhea and abdominal pain. Despite the nutritional benefits of wolfberry honey (from Lycium barbarum L.), its potential to alleviate IBD remains underexplored. This study evaluated the protective effects of wolfberry honey and its extract (wolfberry honey extract [WHE]) against dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) using in vivo and in vitro models. Mice pretreated with wolfberry honey showed significant symptom improvement in DSS-induced UC, linked to reduced expression of proinflammatory markers (Il-1β, Il-6, Tnf-α, and Mcp-1) and increased antioxidant genes (Nrf2, Sod2). Increased Occludin levels indicated improved intestinal barrier function. In vitro, WHE protected DSS-treated Caco-2 cells by lowering reactive oxygen species (ROS), stabilizing mitochondrial membrane potential, and inhibiting TLR4/NF-κB signaling. It enhanced the expression of antioxidant genes and tight junction proteins (ZO-1, Occludin, and Claudin-1). Metabolomic analysis revealed that WHE modulated glycerophospholipid metabolism, increasing phosphatidylcholine and choline levels and decreasing lysophosphatidylcholine levels. These results highlight the potential of wolfberry honey and its extract as nutraceuticals for managing UC through their effects on inflammation, oxidative stress, and intestinal barrier function. Further research is warranted to elucidate their mechanisms of action and assess their long-term therapeutic benefits in IBD management.

The impact of propolis supplementation on inflammatory biomarkers: A meta-analysis and systematic review of randomized controlled clinical trials

Recent interventional investigations suggest the beneficial impact of propolis supplementation on inflammatory biomarkers; however, the results have not been summarized in a comprehensive meta-analysis. We conducted this meta-analysis to summarize all available data and provide clear evidence for whether propolis supplementation affects inflammatory biomarkers. This systematic review with meta-analysis was performed by searching databases (PubMed/Medline, Web of Science, Scopus, and Embase) until February 2024. It included randomized clinical trials (RCTs) assessing the effects of propolis supplementation on inflammatory biomarkers in adults. This review included 20 RCTs with a total of 1139 participants. The propolis supplementation significantly reduced IL-6 (WMD = -2.48; 95 % CI: -4.62, -0.34; P = 0.023) and TNF-α (WMD = -0.86; 95 % CI: -1.45, -0.26; P = 0.005) compared with control groups. Although the CRP concentration was not reduced (WMD = 0.01; 95 % CI: -0.03, 0.05, P = 0.646), a significant reduction in CRP levels was revealed in supplementation durations ≥ 10 weeks. These results suggest that propolis has a beneficial effect on TNF-α and IL-6 levels and may be an effective adjunctive therapy for diseases where inflammation is a key factor in the etiology. Due to the limited number of studies, clinical diversity, and other limitations, it is necessary to conduct more high-quality studies to provide more precise and comprehensive recommendations.

Bee products: An overview of sources, biological activities and advanced approaches used in apitherapy application

Background

Bee therapy (Apitherapy, Api-treatment, Bee treatment) is a type of biotherapy that uses bees and their products as medicinal or preventative measures to control progression of diseases. In many countries today, apitherapy is a section of complementary and integrative medicine. The aim of this review is to explore the different bee products and their therapeutic potentials.

Method

We searched the literature and then explored and evaluated evidence for bee products' composition, therapeutic abilities and novel techniques used to enhance their effectiveness.

Results

Data revealed that there are continuous advances in research and clinical trials of bee therapy. A better understanding of the composition of bee products generated great interest in their use for medical treatments. Bee products either collected or synthesized promote healing through reducing inflammation, enhancing circulation, and inducing a healthy immunological response, Furthermore, researchers have developed innovative approaches such as nanoparticles, scaffold, nanofibers, and others to increase the bioavailability of bee products and overcome problems with the traditional use of these products.

Conclusion

Bee therapy is a simple, accessible, and easy-to-use pharmaceutical that is used in conventional medicine and has the potential to treat a variety of diseases. However, further studies are needed to prove its efficacy, and safety. Lack of practice regulations is still an issue.

Potential Strategies for Overcoming Drug Resistance Pathways Using Propolis and Its Polyphenolic/Flavonoid Compounds in Combination with Chemotherapy and Radiotherapy

Conventional cancer treatments include surgical resection, chemotherapy, hyperthermia, immunotherapy, hormone therapy, and locally targeted therapies such as radiation therapy. Standard cancer therapies often require the use of multiple agents, which can activate nuclear factor kappa B (NF-κB) in tumor cells, leading to reduced cell death and increased drug resistance. Moreover, the use of multiple agents also contributes to added toxicity, resulting in poor treatment outcomes. Cancer cells gradually develop resistance to almost all chemotherapeutics through various mechanisms, such as drug efflux, alterations in drug metabolism and transport, changes in signal transduction pathways, enhanced DNA repair capacity, evasion of apoptosis, increased mutations, reactivation of drug targets, interaction with the cancer microenvironment, cancer cell-stroma interactions, epithelial-mesenchymal transition (EMT)-mediated chemoresistance, epigenetic modifications, metabolic alterations, and the effect of cancer stem cells (CSCs). Developing new strategies to improve chemotherapy sensitivity while minimizing side effects is essential for achieving better therapeutic outcomes and enhancing patients' quality of life. One promising approach involves combining conventional cancer treatments with propolis and its flavonoids. These natural compounds may enhance tumor response to treatment while reducing toxicity. Propolis and its components can sensitize cancer cells to chemotherapeutic agents, likely by inhibiting NF-κB activation, reprogramming tumor-associated macrophages (TAMs; an M2-like phenotype), and thereby reducing the release of matrix metalloproteinase (MMP)-9, cytokines, chemokines, and the vascular endothelial growth factor (VEGF). By reducing TAMs, propolis and its components may also overcome EMT-mediated chemoresistance, disrupt the crosstalk between macrophages and CSCs, inhibit the maintenance of stemness, and reverse acquired immunosuppression, thus promoting an antitumor response mediated by cytotoxic T-cells. This review highlights the potential of flavonoids to modulate the responsiveness of cancer to conventional treatment modalities. The evidence suggests that novel therapeutic strategies incorporating flavonoids could be developed to improve treatment outcomes. The positive effects of combining propolis with chemotherapeutics include reduced cytotoxicity to peripheral blood leukocytes, liver, and kidney cells. Therefore, polyphenolic/flavonoid components may hold potential for use in combination with chemotherapeutic agents in the clinical treatment of various types of cancers.

Potential Antitumor Mechanism of Propolis Against Skin Squamous Cell Carcinoma A431 Cells Based on Untargeted Metabolomics

Propolis is a sticky substance produced by honeybees (Apis mellifera) through the collection of plant resins, which they mix with secretions from their palate and wax glands. Propolis can inhibit tumor invasion and metastasis, thereby reducing the proliferation of tumor cells and inducing cell apoptosis. Previous research has shown that propolis has an inhibitory effect on skin squamous cell carcinoma A431 cells. Nevertheless, its inhibitory mechanism is unclear because of many significantly different Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways between the ethanol extract of the propolis (EEP) group and the control group of cells. In this study, the main components of EEP and the antitumor mechanism at an IC50 of 29.04 μg/mL EEP were determined via untargeted metabolomics determined using ultra high-performance liquid chromatography tandem mass spectrometry (UHPLC‒MS/MS), respectively. The results revealed 43 polyphenolic components in the EEP and 1052 metabolites, with 160 significantly upregulated and 143 significantly downregulated metabolites between cells treated with EEP and solvent. The KEGG enrichment results revealed that EEP significantly inhibited A431 cell proliferation via the steroid hormone biosynthesis and linoleic acid metabolism pathways. These findings may provide valuable insights for the development of targeted therapies for the treatment of cutaneous squamous cell carcinoma.

UHRF1 knockdown induces cell cycle arrest and apoptosis in breast cancer cells through the ZBTB16/ANXA7/Cyclin B1 axis

Ubiquitin-like containing PHD and RING finger domains 1 (UHRF1) is involved in tumorigenicity through DNA methylation in various cancers, including breast cancer. This study aims to investigate the regulatory mechanisms of UHRF1 in breast cancer progression. Herein, we show that UHRF1 is upregulated in breast cancer tissues and cell lines as measured by western blot analysis and immunohistochemistry. Breast cancer cells are transfected with a UHRF1 overexpression plasmid (pcDNA-UHRF1) or short hairpin RNA targeting UHRF1 (sh-UHRF1), followed by detection of cell proliferation, invasion, apoptosis, and cell cycle. UHRF1 overexpression promotes proliferation and invasion and attenuates cell cycle arrest and apoptosis in breast cancer cells, while UHRF1 knockdown shows the opposite effect. Moreover, methylation-specific PCR and ChIP assays indicate that UHRF1 inhibits zinc finger and BTB domain containing 16 (ZBTB16) expression by promoting ZBTB16 promoter methylation via the recruitment of DNA methyltransferase 1 (DNMT1). Then, a co-IP assay is used to verify the interaction between ZBTB16 and the annexin A7 (ANXA7) protein. ZBTB16 promotes ANXA7 expression and subsequently inhibits Cyclin B1 expression. Rescue experiments reveal that ZBTB16 knockdown reverses the inhibitory effects of UHRF1 knockdown on breast cancer cell malignancies and that ANXA7 knockdown abolishes the inhibitory effects of ZBTB16 overexpression on breast cancer cell malignancies. Additionally, UHRF1 knockdown significantly inhibits xenograft tumor growth in vivo. In conclusion, UHRF1 knockdown inhibits proliferation and invasion, induces cell cycle arrest and apoptosis in breast cancer cells via the ZBTB16/ANXA7/Cyclin B1 axis, and reduces xenograft tumor growth in vivo.

Propolis supplementation can reduce serum level of interleukin-6, C-reactive protein, and tumor necrosis factor-α: an updated systematic review and dose-response meta-analysis on randomized clinical trials

BACKGROUND

New evidence suggested that propolis might reduce serum levels of inflammatory mediators; therefore, in this study we aimed to prove the potential effect of propolis on serum levels of interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-α) through conducting a systematic review and meta-analysis.

METHODS

Databases including PubMed, ClinicalTrials.gov, Scopus, Cochrane Library, and ISI Web of Science were searched until October 2023. In the present meta-analysis, we detected the overall effect sizes using extracted standard mean differences (SMD) and the standard deviations (SDs) from both study groups through DerSimonian and Laird method. Exploring the statistical heterogeneity was done through Cochran's Q test and I-squared statistic.

RESULTS

In total, seventeen and sixteen studies were included in the systematic review and meta-analysis, respectively. The overall estimate indicated that the propolis significantly reduced serum levels of IL-6 (SMD = -3.47, 95% confidence interval (95%CI): -5.1, -1.84; p < 0.001), CRP (SMD= -1.73, 95%CI: -2.82, -0.65; p = 0.002), and TNF-α (SMD= -1.42, 95%CI= -2.15, -0.68; p < 0.001). These results also revealed geographical region and propolis dose were the critical points to get the beneficial effects.

CONCLUSION

According to our result, propolis supplementation can decrease serum levels of IL-6, CRP, and TNF-α; therefore, it might be considered as complementary therapy for the treatment of certain chronic diseases.

Chemical Composition of Volatile and Extractive Components of Canary (Tenerife) Propolis

The vegetation of the Canary Islands is characterized by a large number of endemic species confined to different altitudinal levels. It can be assumed that these circumstances determine the characteristic features of the chemical composition of local beekeeping products, including propolis. We report, for the first time, the chemical composition of propolis from Tenerife (Canary Islands). The volatile emissions of three propolis samples collected from different apiaries are represented by 162 C1-C20 compounds, of which 144 were identified using the HS-SPME/GC-MS technique. The main group of volatiles, consisting of 72 compounds, is formed by terpenoids, which account for 42-68% of the total ion current (TIC) of the chromatograms. The next most numerous groups are formed by C6-C17 alkanes and alkenes (6-32% TIC) and aliphatic C3-C11 carbonyl compounds (7-20% TIC). The volatile emissions also contain C1-C6 aliphatic acids and C2-C8 alcohols, as well as their esters. Peaks of 138 organic C3-C34 compounds were recorded in the chromatograms of the ether extracts of the studied propolis. Terpene compounds form the most numerous group, but their number and content in different samples is within very wide limits (9-63% TIC), which is probably due to the origin of the samples from apiaries located at different altitudes. A peculiarity of the chemical composition of the extractive substances is the almost complete absence of phenylcarboxylic acids and flavonoids, characteristic of Apis mellifera propolis from different regions of Eurasia and North America. Aromatic compounds of propolis from Tenerife are represented by a group of nine isomeric furofuranoid lignans, as well as alkyl- and alkenyl-substituted derivatives of salicylic acid and resorcinol.

Antioxidant, antidiabetic effects and polyphenolic contents of propolis from Siirt, Turkey

Propolis, a natural product collected by honeybees from various plant sources, has gained significant attention due to its diverse bioactive compounds and potential therapeutic properties. To further explore its contents and biological activities, this study aimed to analyze the phenolic compounds in Siirt propolis extracts obtained using different solvents, namely ethanol, water, and ethanol-water mixtures. The primary objective of this research was to investigate the phenolic profile, as well as the antidiabetic and antioxidant activities of the propolis extracts. Chemical profiling of extracts was performed using LC-MS/MS. The antioxidant potential of the propolis extracts was evaluated through free radical scavenging methods, including DPPH and ABTS assays. As a result of these analyses, propolis extracts showed moderate radical scavenging potential with 13.86%-35.72% for DPPH and 33.62%-62.50% for ABTS at a concentration of 30 μg mL-1, respectively. This radical scavenging potential of the extracts sheds light on its ability to combat oxidative stress, which is implicated in the development of diabetes, and its potential effects on cellular health. Additionally, the study assessed the antidiabetic properties of the propolis extracts by examining their inhibition effects on α-amylase and α-glycosidase enzymes. Extracts with high phenolic content showed a high inhibitory effect against α-glucosidase with an IC50 of 5.72 ± 0.83 μg mL-1. This research provided significant findings regarding the potential use of propolis in the treatment of diabetes and related metabolic disorders.

Revealing Propolis Potential Activity on Inhibiting Estrogen Receptor and Heat Shock Protein 90 Overexpressed in Breast Cancer by Bioinformatics Approaches

Breast cancer is the most commonly diagnosed cancer globally, with the highest incidence of breast cancer occurring in Asian countries including Indonesia. Among the types of breast cancer, the estrogen receptor (ER)-positive subtype which is prominent with estrogen receptor alpha (ERα) and heat shock protein 90 (HSP90) overexpression genes becomes the most prevalent than the others, approximately 75% of all breast cancer cases. ERα and HSP90 play a role in breast cancer activities including breast tumor growth, invasion, and metastasis mechanism. Propolis, a natural bee product, has been explored for its anticancer activity. However, there is lack of studies that evaluated the potential inhibitor from propolis compounds to the ERα and HSP90 proteins. Therefore, this article focuses on examining the correlation between ERα and HSP90's role in breast cancer and investigating the potential of 93 unique propolis compositions in inhibiting these genes in breast cancer using in silico approaches. This study revealed the positive correlation between ERα and HSP90 genes in breast cancer disease development. Furthermore, we also found novel potential bioactive compounds of propolis against breast cancer through binding with ERα and HSP90; they were 3',4',7-trihydroxyisoflavone and baicalein-7-O-β-D glucopyranoside, respectively. Further research on these compounds is needed to elucidate deeper mechanisms and activity in the real biological system to develop new breast cancer drug treatments.

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.

Chemodiversity of propolis samples collected in various areas of Benin and Congo: Chromatographic profiling and chemical characterization guided by 13 C NMR dereplication

INTRODUCTION

Propolis is a resinous natural substance collected by honeybees from buds and exudates of various trees and plants; it is widely accepted that the composition of propolis depends on the phytogeographic characteristics of the site of collection.

OBJECTIVES

The aim of this study was to determine the phytochemical composition of ethanolic extracts from eight propolis batches collected in different regions of Benin (north, center, and south) and Congo, Africa.

MATERIAL AND METHODS

Characterization of propolis samples was performed by using different hyphenated chromatographic methods combined with carbon-13 nuclear magnetic resonance (¹³ C NMR) dereplication with MixONat software. Their antioxidant or anti-advanced glycation end-product (anti-AGE) activity was then evaluated by using diphenylpicrylhydrazyl and bovine serum albumin assays, respectively.

RESULTS

Chromatographic analyses combined with ¹³ C NMR dereplication showed that two samples from the center of Benin exhibited, in addition to a huge amount of pentacyclic triterpenes, methoxylated stilbenoids or phenanthrenoids, responsible for the antioxidant activity of the extract for the first one. Among them, combretastatins might be cytotoxic. For the second one, the prenylated flavanones known in Macaranga-type propolis were responsible for its significant anti-AGE activity. The sample from Congo was composed of many triterpene derivatives belonging to Mangifera indica species.

CONCLUSION

Therefore, propolis from the center of Benin seems to be of particular interest, due to its antioxidant and anti-AGE properties. Nevertheless, as standardization of propolis is difficult in tropical zones due to its great chemodiversity, a systematic phytochemical analysis is required before promoting the use of propolis in food and health products in Africa.

Propolis: A Detailed Insight of Its Anticancer Molecular Mechanisms

Cancer is the second most life-threatening disease and has become a global health and economic problem worldwide. Due to the multifactorial nature of cancer, its pathophysiology is not completely understood so far, which makes it hard to treat. The current therapeutic strategies for cancer lack the efficacy due to the emergence of drug resistance and the toxic side effects associated with the treatment. Therefore, the search for more efficient and less toxic cancer treatment strategies is still at the forefront of current research. Propolis is a mixture of resinous compounds containing beeswax and partially digested exudates from plants leaves and buds. Its chemical composition varies widely depending on the bee species, geographic location, plant species, and weather conditions. Since ancient times, propolis has been used in many conditions and aliments for its healing properties. Propolis has well-known therapeutic actions including antioxidative, antimicrobial, anti-inflammatory, and anticancer properties. In recent years, extensive in vitro and in vivo studies have suggested that propolis possesses properties against several types of cancers. The present review highlights the recent progress made on the molecular targets and signaling pathways involved in the anticancer activities of propolis. Propolis exerts anticancer effects primarily by inhibiting cancer cell proliferation, inducing apoptosis through regulating various signaling pathways and arresting the tumor cell cycle, inducing autophagy, epigenetic modulations, and further inhibiting the invasion and metastasis of tumors. Propolis targets numerous signaling pathways associated with cancer therapy, including pathways mediated by p53, β-catenin, ERK1/2, MAPK, and NF-κB. Possible synergistic actions of a combination therapy of propolis with existing chemotherapies are also discussed in this review. Overall, propolis, by acting on diverse mechanisms simultaneously, can be considered to be a promising, multi-targeting, multi-pathways anticancer agent for the treatment of various types of cancers.

Propolis and Their Active Constituents for Chronic Diseases

Propolis is a mass of chemically diverse phytoconstituents with gummy textures that are naturally produced by honeybees upon collection of plant resins for utilization in various life processes in beehives. Since ancient times, propolis has been a unique traditional remedy globally utilized for several purposes, and it has secured value in pharmaceutical and nutraceutical areas in recent years. The chemical composition of propolis comprises diverse constituents and deviations in the precise composition of the honeybee species, plant source used for propolis production by bees, climate conditions and harvesting season. Over 300 molecular structures have been discovered from propolis, and important classes include phenolic acids, flavonoids, terpenoids, benzofurans, benzopyrene and chalcones. Propolis has also been reported to have diverse pharmacological activities, such as antidiabetic, anti-inflammatory, antioxidant, anticancer, immunomodulatory, antibacterial, antiviral, antifungal, and anticaries. As chronic diseases have risen as a global health threat, abundant research has been conducted to track propolis and its constituents as alternative therapies for chronic diseases. Several clinical trials have also revealed the potency of propolis and its constituents for preventing and curing some chronic diseases. This review explores the beneficial effect of propolis and its active constituents with credible mechanisms and computational studies on chronic diseases.

Antitumor Effects of Poplar Propolis on DLBCL SU-DHL-2 Cells

Propolis is resinous natural product produced by Western honeybees using beeswax and plant and bud exudates, which has a wide range of biological activities, including antioxidation, antibacterial, anti-inflammation, immune regulation, antitumor, and so on. Diffuse large B-cell lymphoma (DLBCL) is an aggressive cancer, and accounts for about 30% of all lymphomas. The effect of poplar propolis on DLBCL has not been reported. The IC₅₀ of propolis on the proliferation of DLBCL SU-DHL-2 cell line and its proteins and gene expressions were detected by CCK-8 kit, label-free proteomic, and RT-PCR. The results showed that the IC₅₀ of propolis at the 5 × l05/mL cell for 24 h was 5.729 μg/mL. Label-free-based proteomics analysis showed that there were 115 differentially expressed proteins (61 up-regulated and 54 down-regulated proteins) between IC₅₀ dose-treated and solvent control groups. There were 32.47% differential proteins located in the nucleus, 20.78% in the cytoplasm, and 14.29% in mitochondria. The most significant different pathway (p = 0.0016) of protein enrichment was ferroptosis (including glutamate-cysteine ligase regulatory subunit, ferritin, and heme oxygenase). The relative expression trend of 17 of the total 22 genes selected according to proteomics results was in line with their encoded protein. The highest protein-protein interaction was serine/threonine-protein kinase PLK, which interacted with 16 differential proteins. In conclusion, poplar propolis inhibited SU-DHL-2 cells via ferroptosis pathway, accelerating cell death and down-regulated serine/threonine-protein kinase PLK1, affecting apoptosis of cell. This result provides a theoretical basis for the treatment of DLBCL using propolis.

Antineoplastic and Antitrypanosomal Properties of Propolis from Tetragonula biroi Friese

Propolis, popularly known as bee glue, is a resinous, sticky substance produced by different bee species across the globe. Studies on the biological properties of propolis from the Philippines are rare. Hence, the current study aims at the chemical characterization of propolis produced by the stingless bees Tetragonula biroi Friese from the Philippines and to investigate its antitrypanosomal and anticancer properties. The determination of the chemical composition and characterization of propolis samples was achieved using liquid chromatography-mass spectrometry (LC-MS), -high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD), and nuclear magnetic resonance (NMR) spectroscopy. Three major triterpenes were isolated and identified using HRESI-MS and 1H/13C NMR techniques. The spectral studies confirmed the presence of compounds such as isomangiferolic acid, 27-hydoxymangiferonic acid, and 27-hydroxyisomangiferolic acid. All crude propolis samples, isolated fractions, and pure compounds demonstrated moderate antitrypanosomal and anticancer properties compared to control drugs. Amongst the tested compounds, 27-hydoxymangiferonic acid exhibited the highest antitrypanosomal activity at a concentration of 11.6 µg/mL. The highest anticancer effect was demonstrated by the Ph-2 fraction, followed by 27-hydroxyisomangiferolic acid, with IC50 values of 129.6 and 153.3 µg/mL. Thus, it can be concluded that the observed biological activity of Philippine propolis is due to the combinatorial effect or synergistic action of the active compounds 27-hydoxymangiferonic acid and 27-hydroxyisomangiferolic acid.

Cytotoxicity of Propolis Extracts obtained using Dichloromethane and Hexane Solvent on Human Salivary Gland Tumor Cell Line

AIM

This in vitro study aimed to investigate the effect of propolis extracts from two different solvents on human submandibular salivary gland (HSG) tumor cell line.

MATERIALS AND METHODS

Propolis was extracted by dichloromethane (DCM) and hexane (HEX). Crude extracts were prepared from 6.25 to 200 µg/mL in Dulbecco's modified eagle medium without serum. Flavonoid and total phenolic contents of crude extracts were measured using a modified colorimetric method. The cytotoxicity was evaluated by 3-[4, 5-dimethylthiazol-2-yl]-2,5 diphenyl-tetrazolium (MTT) assay and lactate dehydrogenase (LDH) release assay. The statistics were analyzed by independent sample t-test.

RESULTS

Propolis extracts obtained using DCM and HEX exhibited comparable % yield (38.58 and 38.25) and physical characteristics and different amounts of flavonoid (0.439 ± 0.02 and 0.250 ± 0.01 mg catechin/g sample) and total phenolic compounds (3.759 ± 0.03 and 1.618 ± 0.03 mg gallic acid equivalents/g sample). The DCM group at 25, 50, 100, and 200 µg/mL as well as the HEX group at 50, 100, and 200 µg/mL significantly displayed a decrease in % cell viability and an increase in % cytotoxicity, compared with the untreated control group (P < 0.05). The DCM group showed the half-maximal inhibitory concentration (IC50) of MTT (42.93 ± 2.70) and LDH (34.94 ± 0.22). The HEX group showed the IC50 of MTT (61.30 ± 5.39) and LDH (42.32 ± 1.00). Propolis extracts obtained using both DCM and HEX are effective to inhibit HSG viability.

CONCLUSION

Regarding to the cell morphological observation, MTT and LDH assays, propolis extracts obtained using DCM and HEX exhibited the cytotoxic effect on HSG tumor cell line. Based on our knowledge, this research demonstrates the first preliminary result suggesting propolis as a natural product of choice for salivary gland cancer prevention and therapy.

Propolis: Its Role and Efficacy in Human Health and Diseases

With technological advancements in the medicinal and pharmaceutical industries, numerous research studies have focused on the propolis produced by stingless bees (Meliponini tribe) and Apis mellifera honeybees as alternative complementary medicines for the potential treatment of various acute and chronic diseases. Propolis can be found in tropical and subtropical forests throughout the world. The composition of phytochemical constituents in propolis varies depending on the bee species, geographical location, botanical source, and environmental conditions. Typically, propolis contains lipid, beeswax, essential oils, pollen, and organic components. The latter include flavonoids, phenolic compounds, polyphenols, terpenes, terpenoids, coumarins, steroids, amino acids, and aromatic acids. The biologically active constituents of propolis, which include countless organic compounds such as artepillin C, caffeic acid, caffeic acid phenethyl ester, apigenin, chrysin, galangin, kaempferol, luteolin, genistein, naringin, pinocembrin, coumaric acid, and quercetin, have a broad spectrum of biological and therapeutic properties such as antidiabetic, anti-inflammatory, antioxidant, anticancer, rheumatoid arthritis, chronic obstruct pulmonary disorders, cardiovascular diseases, respiratory tract-related diseases, gastrointestinal disorders, as well as neuroprotective, immunomodulatory, and immuno-inflammatory agents. Therefore, this review aims to provide a summary of recent studies on the role of propolis, its constituents, its biologically active compounds, and their efficacy in the medicinal and pharmaceutical treatment of chronic diseases.

Propolis: An update on its chemistry and pharmacological applications

Propolis, a resinous substance produced by honeybees from various plant sources, has been used for thousands of years in traditional medicine for several purposes all over the world. The precise composition of propolis varies according to plant source, seasons harvesting, geography, type of bee flora, climate changes, and honeybee species at the site of collection. This apiary product has broad clinical applications such as antioxidant, anti-inflammatory, antimicrobial, anticancer, analgesic, antidepressant, and anxiolytic as well asimmunomodulatory effects. It is also well known from traditional uses in treating purulent disorders, improving the wound healing, and alleviating many of the related discomforts. Even if its use was already widespread since ancient times, after the First and Second World War, it has grown even more as well as the studies to identify its chemical and pharmacological features, allowing to discriminate the qualities of propolis in terms of the chemical profile and relative biological activity based on the geographic place of origin. Recently, several in vitro and in vivo studies have been carried out and new insights into the pharmaceutical prospects of this bee product in the management of different disorders, have been highlighted. Specifically, the available literature confirms the efficacy of propolis and its bioactive compounds in the reduction of cancer progression, inhibition of bacterial and viral infections as well as mitigation of parasitic-related symptoms, paving the way to the use of propolis as an alternative approach to improve the human health. However, a more conscious use of propolis in terms of standardized extracts as well as new clinical studies are needed to substantiate these health claims.

An Insight into Anticancer Effect of Propolis and Its Constituents: A Review of Molecular Mechanisms

Propolis is a natural compound collected by honeybees from different parts of plants. Honeybees produce a sticky component besides honey by mixing the tree resin and other botanical sources with saliva called propolis or bee glue. Propolis was traditionally used as a wound healing substance, cosmetic, medicine, and many other conditions. Till now, there is no definite curable treatment for most cancers and chemotherapeutic drugs and drugs used for targeted therapies have serious side effects. According to a recent research, natural products are becoming increasingly essential in cancer prevention. Natural products are a great source of potential therapeutic agents, especially in the treatment of cancer. Previous studies have reported that the presence of caffeic acid phenethyl ester (CAPE), artepillin C, and chrysin is responsible for the anticancer potential of propolis. Most of the previous studies suggested that propolis and its active compounds inhibit cancer progression by targeting multiple signaling pathways including phosphoinositide 3-kinases (PI3K)/Akt and mitogen-activated protein kinase (MAPK) signaling molecules, and induce cell cycle arrest. Induction of apoptosis by propolis is mediated through extrinsic and intrinsic apoptotic pathways. The aim of this review is to highlight and summarize the molecular targets and anticancer potential of propolis and its active compounds on cell survival, proliferation, metastasis, and apoptosis in cancer cells.

Antimicrobial Activity of Propolis Extract and Their Application as a Natural Preservative in Livestock Products: A Meta-Analysis

This study aimed to evaluate the effectiveness of propolis extract as a natural preservative for livestock products in term of chemical and microbiological characteristics by meta-analysis. The stages carried out in this study were identification, selection, checking suitability, and the resulting selected articles were used in the meta-analysis. The selection results obtained a total of 22 selected journal articles consisting of 9 articles for analysis of the antimicrobial activity of propolis extract and 13 articles for analysis of the chemical and mirobiological characteristics of livestock products. The articles were obtained from electronic databases, namely Science Direct and Google Scholar. The model used in this study is the random-effect model involving two groups, control and experimental. Heterogeneity and effect size values were carried out in this study using Hedge's obtained through openMEE software. Forest plot tests and data validation on publication bias was obtained using Kendall's test throught JASP 0.14.1 software. The results showed that there is a significant relationship between propolis extract with the results of the antimicrobial activity (p<0.05). In addition, the results of the application of propolis extract on the livestock products for the test microbes and the value of thiobarbituric acid reactive substances (TBARs) showed significant results (p<0.05). Conclusion based on the random-effect model on the effectiveness of antimicrobial activity of propolis extract and their apllication as a natural preservative of the chemical and microbiological characteristics of livestock products is valid by Kendall's test (p>0.05). Propolis in this case effectively used as natural preservatives in livestock products.

The Potential Use of Propolis as an Adjunctive Therapy in Breast Cancers

Propolis is a resinous beehive product that has a wide range of biological activities, namely antimicrobial, antioxidant, and anti-inflammatory properties. Propolis is collected by the bees from plant resin and exudates to protect hives and maintain hive homeostasis. The aim of the present systematic scoping review is to explore the potential and suitability of propolis as an adjunctive treatment in breast cancers, based on the latest available experimental evidence (2012-2021). After applying the exclusion criteria, a total of 83 research publications were identified and retrieved from Scopus, Web of Science, and Pubmed. Several relevant key themes identified from the included studies were cytotoxicity, synergistic/combination treatment, improvement in bioavailability, human clinical trials, and others. A majority of the studies identified were still in the in vitro and in vivo stages. Nonetheless, we managed to identify 4 human clinical trials that demonstrated the successful use of propolis in alleviating side effects of chemotherapy and radiotherapy while increasing the quality of life of breast cancer patients, with minimal adverse effects. In conclusion, propolis, as an adjunctive treatment, may have therapeutic benefits in alleviating symptoms related to breast cancers. However, further clinical trials, preferably with higher number of participants/subjects/patients, are urgently needed.

Brazilian green propolis: A novel tool to improve the cytotoxic and immunomodulatory action of docetaxel on MCF-7 breast cancer cells and on women monocyte

Docetaxel (DTX) is used against breast cancer despite its side effects such as toxicity and immunosuppression. Here we investigated the cytotoxic and immunomodulatory effects of the ethanol solution extract of propolis (EEP) in combination with DTX on MCF-7 breast cancer cells and on women's monocyte. The cytotoxic potential of EEP + DTX was assessed by MTT assay and the type of tumor cell death was evaluated by flow cytometry. The effects of EEP + DTX on the migration and invasion of MCF-7 cells were analyzed. Cytokine production by monocytes was assessed by ELISA and the expression of cell surface markers was evaluated by flow cytometry. We also assessed the fungicidal activity of monocytes against Candida albicans and the generation of reactive oxygen species (ROS). Finally, the impact of the supernatants of treated monocytes in the viability, migration, and invasiveness of tumor cells was assessed. EEP enhanced the cytotoxicity of DTX alone against MCF-7 cells by inducing necrosis and inhibiting their migratory ability. EEP + DTX exerted no cytotoxic effects on monocytes and stimulated HLA-DR expression, TNF-α, and IL-6 production, exerted an immunorestorative action in the fungicidal activity, and reduced the oxidative stress. Our findings have practical implications and reveal new insights for complementary medicine.

Activity of antifungal drugs and Brazilian red and green propolis extracted with different methodologies against oral isolates of Candida spp

Background

Oral candidiasis is an opportunistic disease caused by fungi of the Candida genus. The occurrence of Candida spp. resistance to the commercial antifungal drugs points to the search for alternative treatments. Propolis has been successfully used in the treatment of infectious diseases for centuries. It has been proposed that an ultrasound pretreatment in the propolis extraction protocol can enhance the concentrations of molecules with antimicrobial activities in the final extract. Thus, this study aimed to compare the antifungal activity against oral Candida spp. isolates of green and red propolis extracts submitted or not to an ultrasound pretreatment before the extraction procedure.

Methods

Candida spp. were isolated from denture stomatitis lesions and identified by sequencing. Oral Candida spp. isolates and reference strains were submitted to broth microdilution assays using commercial antifungals and Brazilian green and red propolis extracts submitted or not to an ultrasound pretreatment. Minimal Inhibitory Concentrations (MIC) and Minimal Fungicide Concentrations (MFC) were determined and biofilm formation interference was evaluated for resistant isolates.

Results

C. albicans, Candida tropicalis and Candida dubliniensis were isolated from denture stomatitis lesions. Growth inhibition was observed in all Candida isolates incubated with all green and red propolis extracts. At lower doses, red propolis extracts presented significant antifungal activity. The ultrasound pretreatment did not promote an increase in the antifungal activity of green or red propolis. Three isolates, which were highly resistant to fluconazole and itraconazole, were susceptible to low doses of red propolis extracts. These same three specimens had their biofilm formation inhibted by red propolis ethanolic extract.

Conclusions

Thus, red propolis can be faced as a promising natural product to be used in the auxiliary antifungal therapy of denture stomatitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03445-5.

Bioactive components and mechanisms of poplar propolis in inhibiting proliferation of human hepatocellular carcinoma HepG2 cells

BACKGROUND

The aim of this study was to elucidate the bioactive components and anti-tumor mechanism of poplar propolis extract obtained from North China (CP) in human hepatocellular carcinoma HepG2 cells in vitro.

METHODS

Cell viability and proliferation were measured by SRB assay and EdU proliferation test kit, respectively. Cell migration was evaluated by scratching test. Reactive oxygen species (ROS) production and mitochondrial membrane potential were investigated with the fluorescent probes, DCHF and JC-1, respectively. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were inspected by measurement kits. Apoptosis was assessed by acridine orange (AO) and Hoechst 33258 staining. Levels of Bax, Bcl-2, caspase 9, caspase 3, PARP, MMP-2, MMP-9, PI3K/p-PI3K, AKT/p-AKT, p38MAPK/p-p38 MAPK, ERK/p-ERK, LATS2, YAP, TAZ and TEAD1 were assessed by western blotting, respectively.

RESULTS

The bioactive components of CP inhibiting HepG2 cells were mainly flavonoids, and esters. CP induced HepG2 apoptosis through a mitochondrial-dependent intrinsic pathway with elevated the levels of cleaved PARP, cleaved caspase 3, and Bax and decreased the expressions of Bcl-2 and procaspase 9. It seemed that CP triggered apoptosis by activation of the p38 MAPK and inactivation of p-ERK. More importantly, we found that CP suppressed the Hippo pathway, leading to inactivation of YAP/TAZ and TEAD1 and inhibition of PI3K/AKT signaling molecules.

CONCLUSION

CP exerted excellent anti-proliferation and pro-apoptosis actions in HepG2 cells by inactivation of the loop between the Hippo/YAP and PI3K/AKT pathways, and may be a promising therapy for HCC.

Polyphenolics profile effects upon the antioxidant and antimicrobial activity of propolis extracts

Propolis, a complex bee product, is a source of numerous bioactive principles, beneficial for human health, therefore it is intensively studied. In the present work, extracts of propolis from Bihor Romanian County were studied to identify the relationship between the polyphenolic derivatives profile and their antioxidant and antimicrobial activity. Extracts were obtained using water and 25%, 50%, and 70% ethanolic solutions (w/w), at 2:1, 4:1, and 6:1 liquid: solid ratios (w/w). 21 polyphenolic derivatives were quantified by UHPLC-MS, proving that the extracts composition strongly depends on the solvent. The sum of quantified polyphenolics extracted varied between 1.5 and 91.2 mg/g propolis. The antioxidant capacity was evaluated using the free radicals 2,2’-azino-bis (3-ethylbenzothiazoline-6 sulfonic acid) diammonium salt (ABTS) and 1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging methods. Antimicrobial efficiency was tested against Gram-positive (B. subtilis), Gram-negative bacteria (E. coli), and fungi (C. albicans) by disc-diffusion method. All extracts, even the aqueous ones, demonstrated antibacterial and antifungal activity. Chemometric methods (partial least squares) and a saturation-type model were used to evaluate the contribution of various bioactive principles in building the antioxidant capacity of extracts. Both experimental and modelling results show that 50% ethanolic extracts provide a rich polyphenolics profile and ensure a good antioxidant capacity.

Bee Products: A Representation of Biodiversity, Sustainability, and Health

Biodiversity strengthens the productivity of any ecosystem (agricultural land, forest, lake, etc.). The loss of biodiversity contributes to food and energy insecurity; increases vulnerability to natural disasters, such as floods or tropical storms; and decreases the quality of both life and health. Wild and managed bees play a key role in maintaining the biodiversity and in the recovery and restoration of degraded habitats. The novelty character of this perspective is to give an updated representation of bee products’ biodiversity, sustainability, and health relationship. The role of bees as bioindicators, their importance in the conservation of biodiversity, their ecosystem services, and the variety of the bee products are described herein. An overview of the main components of bee products, their biological potentials, and health is highlighted and detailed as follows: (i) nutritional value of bee products, (ii) bioactive profile of bee products and the related beneficial properties; (iii) focus on honey and health through a literature quantitative analysis, and (iv) bee products explored through databases. Moreover, as an example of the interconnection between health, biodiversity, and sustainability, a case study, namely the “Cellulose Park”, realized in Rome (Italy), is presented here. This case study highlights how bee activities can be used to assess and track changes in the quality of agricultural ecosystems—hive products could be valid indicators of the quality and health of the surrounding environment, as well as the changes induced by the biotic and abiotic factors that impact the sustainability of agricultural production and biodiversity conservation in peri-urban areas.

Metabolomic Identification of Anticancer Metabolites of Australian Propolis and Proteomic Elucidation of Its Synergistic Mechanisms with Doxorubicin in the MCF7 Cells

The combination of natural products with standard chemotherapeutic agents offers a promising strategy to enhance the efficacy or reduce the side effects of standard chemotherapy. Doxorubicin (DOX), a standard drug for breast cancer, has several disadvantages, including severe side effects and the development of drug resistance. Recently, we reported the potential bioactive markers of Australian propolis extract (AP-1) and their broad spectrum of pharmacological activities. In the present study, we explored the synergistic interactions between AP-1 and DOX in the MCF7 breast adenocarcinoma cells using different synergy quantitation models. Biochemometric and metabolomics-driven analysis was performed to identify the potential anticancer metabolites in AP-1. The molecular mechanisms of synergy were studied by analysing the apoptotic profile via flow cytometry, apoptotic proteome array and measuring the oxidative status of the MCF7 cells treated with the most synergistic combination. Furthermore, label-free quantification proteomics analysis was performed to decipher the underlying synergistic mechanisms. Five prenylated stilbenes were identified as the key metabolites in the most active AP-1 fraction. Strong synergy was observed when AP-1 was combined with DOX in the ratio of 100:0.29 (w/w) as validated by different synergy quantitation models implemented. AP-1 significantly enhanced the inhibitory effect of DOX against MCF7 cell proliferation in a dose-dependent manner with significant inhibition of the reactive oxygen species (p < 0.0001) compared to DOX alone. AP-1 enabled the reversal of DOX-mediated necrosis to programmed cell death, which may be advantageous to decline DOX-related side effects. AP-1 also significantly enhanced the apoptotic effect of DOX after 24 h of treatment with significant upregulation of catalase, HTRA2/Omi, FADD together with DR5 and DR4 TRAIL-mediated apoptosis (p < 0.05), contributing to the antiproliferative activity of AP-1. Significant upregulation of pro-apoptotic p27, PON2 and catalase with downregulated anti-apoptotic XIAP, HSP60 and HIF-1α, and increased antioxidant proteins (catalase and PON2) may be associated with the improved apoptosis and oxidative status of the synergistic combination-treated MCF7 cells compared to the mono treatments. Shotgun proteomics identified 21 significantly dysregulated proteins in the synergistic combination-treated cells versus the mono treatments. These proteins were involved in the TP53/ATM-regulated non-homologous end-joining pathway and double-strand breaks repairs, recruiting the overexpressed BRCA1 and suppressed RIF1 encoded proteins. The overexpression of UPF2 was noticed in the synergistic combination treatment, which could assist in overcoming doxorubicin resistance-associated long non-coding RNA and metastasis of the MCF7 cells. In conclusion, we identified the significant synergy and highlighted the key molecular pathways in the interaction between AP-1 and DOX in the MCF7 cells together with the AP-1 anticancer metabolites. Further in vivo and clinical studies are warranted on this synergistic combination.

Chinese Propolis Suppressed Pancreatic Cancer Panc-1 Cells Proliferation and Migration via Hippo-YAP Pathway

Pancreatic cancer is one of the most malignant cancers with high mortality. Therefore, it is of great urgency to develop new agents that could improve the prognosis of Pancreatic cancer patients. Chinese propolis (CP), a flavonoid-rich beehive product, has been reported to have an anticancer effect. In this study, we applied CP to the human Pancreatic cancer cell line Panc-1 to verify its impact on tumor development. CP induced apoptosis in Panc-1 cells from 12.5 µg/mL in a time- and dose-dependent manner with an IC₅₀ value of approximately 50 µg/mL. Apoptosis rate induced by CP was examined by Annexing FITC/PI assay. We found that 48 h treatment with 50 µg/mL CP resulted in 34.25 ± 3.81% apoptotic cells, as compared to 9.13 ± 1.76% in the control group. We further discovered that the Panc-1 cells tended to be arrested at G2/M phase after CP treatment, which is considered to contribute to the anti-proliferation effect of CP. Furthermore, our results demonstrated that CP suppressed Panc-1 cell migration by regulating epithelial-mesenchymal transition (EMT). Interestingly, the Hippo pathway was activated in Panc-1 cells after CP treatment, serving as a mechanism for the anti-pancreatic cancer effect of CP. These findings provide a possibility of beehive products as an alternative treatment for pancreatic cancer.

Co-administration of Aluminum Sulfate and Propolis Regulates Matrix Metalloproteinases-2/9 Expression and Improves the Uterine Leiomyoma in Adult Rat Model

The aim of this study was to evaluate the effects of aluminum sulfate (alum) with propolis (PR) on uterine leiomyoma (UL) in rat model. One hundred and four female Wistar rats (180-200 g) were allocated into two main groups of control (Co, n = 8) and experiment (UL model [estradiol benzoate 200 μg/kg/IM twice/week/8 weeks] with/without treatment) defined in 13 subgroups with/without treatment with coil oil (UL + COi), PR (100 or 200 mg/kg) as UL + PR100 or 200, alum (35, 75 or 150 mg/Kg) as UL + AL 35, 75, or 150, and PR (100 mg/kg or 200) with alum (35, 75, or 150 mg/Kg) as UL + PR100 or 200 + AL35, 75, or 150. Subgroups received doses of therapeutics for 14 days (IP). In the end, rats were sacrificed, and the uteri were isolated for molecular and histopathological investigations. The myometrium thickness, collagen contents, and gene expression of MMP-2 and 9 increased significantly in experimental groups with/without treatment (P ˂ 0.05). PR administration (100 and 200 mg/kg) alone or with alum (35 and 75 mg/kg) significantly decreased myometrium collagen contents and the gene expression and protein concentration of MMP-2 and 9 compared with UL and UL + Coi subgroups (P ˂ 0.05). Alum (75 mg/kg) with PR (200 mg/kg) could improve UL features and reduce MMP-2 and 9 gene expression.

Effects of propolis and its bioactive components on breast cancer cell pathways and the molecular mechanisms involved

BACKGROUND

Breast cancer is a female malignancy that is a significant cause of mortality worldwide. Currently, investigations on natural ingredients as new candidates for chemopreventive agents and breast cancer chemotherapies are increasing. Propolis is a natural resinous material produced by honeybees that exhibit anticancer potential. Several studies have mentioned the major bioactive compounds of propolis, but their mechanism of action is not clearly understood.

OBJECTIVES

The purpose of this review is to collect and summarize the evidence related to the effectiveness of propolis and its bioactive contents as candidates for breast cancer therapy and analyze the molecular mechanisms involved in their therapeutic pathways.

METHODS

We reviewed 94 articles from journals and databases, extracted the results, and produced summaries and conclusions.

RESULTS

Propolis and its bioactive ingredients show cytotoxic, anti-proliferative, pro-autophagic, anti-metastatic, and antioxidant activities, as well as synergistic effects with chemotherapy or radiotherapy in breast cancer. Its therapeutic activity involves various target molecules, including NF-κβ, Fas receptors, p53, TLR4, ANXA7, and voltage-gated Na+ channel (VGSC).

CONCLUSION

The bioactive components of propolis and the target molecules involved need to be explored further to develop new breast cancer therapies and overcome the problem of chemoradiation resistance.

Comparative Study of Lipophilic Statin Activity in 2D and 3D in vitro Models of Human Breast Cancer Cell Lines MDA-MB-231 and MCF-7

Introduction

Statins are a type of drugs that are used to lower cholesterol level in blood. Since the early 1990s, it has been known that statins could be beneficial in cancer therapy. However, data remain controversial, especially regarding estrogen receptors status. Despite many studies in breast cancer models in vitro, the correlations of effects of separate statins in various model systems remain unclear.

Aim

Our aim was to evaluate the anticancer activity of lovastatin, mevastatin, pitavastatin and simvastatin on different subtypes of human breast cancer (MDA-MB-231 and MCF-7 cell lines) in spatially different 2D and 3D cultures in vitro.

Materials and Methods

Cell viability was tested using MTT assay. Effect of statins on cell colony formation was evaluated by calculating breast cancer cell colony area and number. The effect on cell migration was estimated by “wound healing” assay. The activity of compounds in 3D cultures was evaluated by measuring the spheroid size changes during incubation.

Results

Among the tested statins, pitavastatin had the greatest effect on the viability of breast cancer MDA-MB-231 and MCF-7 cell lines. The mevastatin and pitavastatin mostly decreased the MDA-MB-231 and MCF-7 cell colony formation. All statins at 90% of their estimated effective concentration (EC₅₀) and simvastatin at 10% of its EC₅₀ concentration suppressed the MCF-7 cells migration in “wound healing” assay. Only higher concentrations of mevastatin and pitavastatin slowed down the MDA-MB-231 cell migration. Statins showed different activity on 3D cell cultures growth. Lovastatin and simvastatin delayed the growth of MDA-MB-231 cell spheroids, while mevastatin and pitavastatin reduced the growth of MCF-7 spheroids.

Conclusion

Statins possess different anticancer activity in human breast cancer MDA-MB-231 and MCF-7 cell cultures. Pitavastatin and simvastatin showed the highest activity in most tested assays, especially against MCF-7 cell line.

Preclinical approaches in vulvovaginal candidiasis treatment with mucoadhesive thermoresponsive systems containing propolis

Vulvovaginal candidiasis (VVC) is a common vaginitis that affects women, especially in childbearing age, caused by Candida albicans in almost 80% of cases. Considering the limited drug arsenal available and the increasing fungal resistance profile, the search for new therapeutic sources with low toxicity and easy administration should be supported. Propolis has been used as a traditional medicine for multiple diseases, considering its particular composition and pharmaceutical properties that permits its wide applicability; it has also emerged as a potential antifungal agent. Thus, this study performed an in vitro and in vivo investigation into the efficacy of a new mucoadhesive thermoresponsive platform for propolis delivery (MTS-PRPe) in a preclinical murine model of VVC treatment caused by C. albicans. The methodologies involved chemical analysis, an assessment of the rheological and mucoadhesive properties of propolis formulations, in vitro and in vivo antifungal evaluations, histological evaluations and electron microscopy of the vaginal mucosa. The results demonstrated the antifungal activity of propolis extract and MTS-PRP against the standard strain and a fluconazole-resistant clinical isolate of C. albicans, in both in vitro and in vivo assays. These results were similar and even better, depending on the propolis concentration, when compared to nystatin. Thus, the formulation containing propolis exhibited good performance against C. albicans in a vulvovaginal candidiasis experimental model, representing a promising opportunity for the treatment of this infection.

Molecular and cellular mechanisms of the effects of Propolis in inflammation, oxidative stress and glycemic control in chronic diseases

Propolis is a sticky, resinous material gather from plants and is blended with wax and other constituents. It is reported to have anti-inflammatory, anti-oxidative and blood glucose-lowering properties. This review aims to summarise evidences for the cellular and molecular mechanism of Propolis in inflammation, oxidative stress, and glycemic control. Propolis stimulate the production and secretion of anti-inflammatory cytokines and to inhibit the production of inflammatory cytokines and due to its various antioxidant and poly-phenolic compounds may has a role in control and treating some of the chronic diseases. Most studies have shown that Propolis may affect metabolic factors including plasma insulin levels, and it has proposed that it could be used in the prevention and treatment of T2D Mellitus. In general, to demonstrate the definite effects of Propolis on chronic diseases, more studies are required using larger sample sizes and various doses of Propolis, using better characterized and standardized agents.

Chinese Propolis Inhibits the Proliferation of Human Gastric Cancer Cells by Inducing Apoptosis and Cell Cycle Arrest

Special Chinese propolis sourced from the Changbai Mountains (CBMP) in Northeast China is rich in specific flavonoids and phenolic acids and its bioactivity has not been reported. This study aimed to investigate the antiproliferative effect of CBMP on cancer cells and its molecular mechanisms. Different cancer cell lines were treated with the ethanol extracts of CBMP for 24 hours before the cell viability and mechanism measurements. The results showed CBMP had weak activities against human pancreatic cancer cell PANC1, human lung cancer cell A549, human colon cancer cell HCT116, human liver cancer cell HepG2, human bladder cancer cell T24, and human breast cancer cell MDA-MB-231, but it significantly inhibited the growth of human gastric cancer SGC-7901 cells, caused cell apoptosis and cell cycle arrest in S phase, with increased production of reactive oxygen species (ROS) and reduced mitochondrial membrane potential (MMP). The results indicate that Chinese propolis sourced from the Changbai Mountains selectively inhibits the proliferation of human gastric cancer SGC-7901 cells by inducing both death receptor-induced apoptosis and mitochondria-mediated apoptosis, and cell cycle arrest in S phase. These activities and mechanisms help understand the anticancer action of propolis and its active compounds.

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

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

Chemopreventive Effects of Propolis in the MNU-Induced Rat Mammary Tumor Model

Currently, one of the central problems in cancer management is the relapse of disease following conventional treatments, yet few therapeutic agents targeting resistance and tolerance exist. Propolis is known as a healing agent since ancient times. Therefore, over time, its curative properties have kept the interest of scientists, thus leading permanently to investigations of its other possible undiscovered effects. In this context, current experiments were performed to establish the chemopreventive potential of propolis extract (PE) (1.05 mg/kg BW/day) in N-methyl-N-nitrosourea- (MNU-) induced rat mammary tumors. MNU-inoculated/PE-treated rats had tumors of different physical attributes compared with control rats MNU-inoculated. The number of developed tumors (mean 49% versus 100%), incidence (mean 49% versus 100%), multiplicity (1.8 versus 3.7 (p < 0.001)), tumor volume (mean 10 cm³ versus 16 cm³ (p < 0.001)), and weight of the tumor mass (mean 7.42 g versus 9.00 g (p < 0.05)) were noted. The numbers of grade I tumors recorded for MNU-inoculated rats were 24 (Group 1) and 7 (Group 2) for MNU-induced/PE-treated rats. In the serum of rats MNU-inoculated/PE-treated were found higher levels of antioxidative enzymes (SOD, CAT, and GPx) than in MNU-induced. Taken together, these data indicate that propolis could be a chemopreventive agent against MNU-induced mammary carcinogenesis.

Evaluation of the Impact of Imprinted Polymer Particles on Morphology and Motility of Breast Cancer Cells by Using Digital Holographic Cytometry

Breast cancer is the second most common cancer type worldwide and breast cancer metastasis accounts for the majority of breast cancer-related deaths. Tumour cells produce increased levels of sialic acid (SA) that terminates the monosaccharide on glycan chains of the glycosylated proteins. SA can contribute to cellular recognition, cancer invasiveness and increase the metastatic potential of cancer cells. SA-templated molecularly imprinted polymers (MIPs) have been proposed as promising reporters for specific targeting of cancer cells when deployed in nanoparticle format. The sialic acid-molecularly imprinted polymers (SA-MIPs), which use SA for the generation of binding sites through which the nanoparticles can target and stain breast cancer cells, opens new strategies for efficient diagnostic tools. This study aims at monitoring the effects of SA-MIPs on morphology and motility of the epithelial type MCF-7 and the highly metastatic MDAMB231 breast cancer cell lines, using digital holographic cytometry (DHC). DHC is a label-free technique that is used in cell morphology studies of e.g., cell volume, area and thickness as well as in motility studies. Here, we show that MCF-7 cells move slower than MDAMB231 cells. We also show that SA-MIPs have an effect on cell morphology, motility and viability of both cell lines. In conclusion, by using DH microscopy, we could detect SA-MIPs impact on different breast cancer cells regarding morphology and motility.

Tumor-suppressing potential of stingless bee propolis in in vitro and in vivo models of differentiated-type gastric adenocarcinoma

The protective property of propolis across a wide spectrum of diseases has long been realized, yet the anti-tumor efficacy of this bioactive substance from Philippine stingless bees has remained poorly understood. Here, we showed the tumor-suppressing potential of crude ethanolic extract of Philippine stingless bee propolis (EEP) in in vitro models of gastric cancer highlighting the first indication of remarkable subtype specificity towards differentiated-type human gastric cancer cell lines but not the diffuse-type. Mechanistically, this involved the profound modulation of several cell cycle related gene transcripts, which correlated with the prominent cell cycle arrest at the G0/G1 phase. To reinforce our data, a unique differentiated-type gastric cancer model, A4gnt KO mice, together with age-matched 60 week-old C57BL/6 J mice were randomly assigned to treatment groups receiving distilled water or EEP for 30 consecutive days. EEP treatment induced significant regression of gross and histological lesions of gastric pyloric tumors that consistently corresponded with specific transcriptional regulation of cell cycle components. Also, the considerable p21 protein expression coupled with a marked reduction in rapidly dividing BrdU-labeled S-phase cells unequivocally supported our observation. Altogether, these findings support the role of Philippine stingless bee propolis as a promising adjunct treatment option in differentiated-type gastric cancer.

The effect of propolis administration on fetal development

Propolis is one of the bee products that widely used in health therapy. However, there has no study evaluating the developmental toxicity of propolis. This study was aimed to analyze the effect of propolis administration during pregnancy on fetal development. The pregnant mice were divided into five groups including control group (Tween 80 1%), low-dose (380 mg/kg b.wt.) and high-dose (1400 mg/kg b.wt.) of water extract of propolis from Banten (WEB), and low-dose (380 mg/kg b.wt.) and high-dose (1400 mg/kg b.wt.) of ethanol extract of propolis from South Sulawesi (EES). Propolis was administered for 18 days of gestation and then sacrificed to analyze the fetal development by examining external and skeletal abnormalities. The histopathological examination of placenta was also conducted. The result showed both low-dose groups did not inhibit fetal development. However, the high-dose of EES significantly reduced the weight, crown-rump of fetuses and increased the number of resorption (p < 0.05). Fetal weight was the only significantly reduced parameter of fetal growth in the highdose group of WEB (p < 0.05). The histopathological examination of placenta showed a reduction of labyrinth development in both high-dose groups. Dose of 380 mg/kg dose of Indonesian propolis is relatively safe for consumption during pregnancy.

Ricinus communis L. fruit extract inhibits migration/invasion, induces apoptosis in breast cancer cells and arrests tumor progression in vivo

Medicinal plant-based therapies can be important for treatment of cancer owing to high efficiency, low cost and minimal side effects. Here, we report the anti-cancer efficacy of Ricinus communis L. fruit extract (RCFE) using estrogen positive MCF-7 and highly aggressive, triple negative MDA-MB-231 breast cancer cells. RCFE induced cytotoxicity in these cells in dose and time-dependent manner. It also demonstrated robust anti-metastatic activity as it significantly inhibited migration, adhesion, invasion and expression of matrix metalloproteinases (MMPs) 2 and 9 in both cell lines. Further, flow cytometry analysis suggested RCFE-mediated induction of apoptosis in these cells. This was supported by attenuation of anti-apoptotic Bcl-2, induction of pro-apoptotic Bax and caspase-7 expressions as well as PARP cleavage upon RCFE treatment. RCFE (0.5 mg/Kg body weight) treatment led to significant reduction in tumor volume in 4T1 syngeneic mouse model. HPLC and ESI-MS analysis of active ethyl acetate fraction of RCFE detected four compounds, Ricinine, p-Coumaric acid, Epigallocatechin and Ricinoleic acid. Individually these compounds showed cytotoxic and migration-inhibitory activities. Overall, this study for the first time demonstrates the anti-cancer efficacy of the fruit extract of common castor plant which can be proposed as a potent candidate for the treatment of breast cancer.

p-Coumaric Acid Has Protective Effects against Mutant Copper-Zinc Superoxide Dismutase 1 via the Activation of Autophagy in N2a Cells

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the selective death of motor neurons. In previous our study, an ethanol extract of Brazilian green propolis (EBGP) prevented mutant copper-zinc superoxide dismutase 1 (SOD1^mut)-induced neurotoxicity. This paper aims to reveal the effects of p-coumaric acid (p-CA), an active ingredient contained in EBGP, against SOD1^mut-induced neurotoxicity. We found that p-CA reduced the accumulation of SOD1^mut subcellular aggregation and prevented SOD1^mut-associated neurotoxicity. Moreover, p-CA attenuated SOD1^mut-induced oxidative stress and endoplasmic reticulum stress, which are significant features in ALS pathology. To examine the mechanism of neuroprotective effects, we focused on autophagy, and we found that p-CA induced autophagy. Additionally, the neuroprotective effects of p-CA were inhibited by chloroquine, an autophagy inhibiter. Therefore, these results obtained in this paper suggest that p-CA prevents SOD1^mut-induced neurotoxicity through the activation of autophagy and provides a potential therapeutic approach for ALS.

Neurotoxic Effect of Ethanolic Extract of Propolis in the Presence of Copper Ions is Mediated through Enhanced Production of ROS and Stimulation of caspase-3/7 Activity

Elevated amounts of copper are considered to be contributing factor in the progression of neurodegenerative diseases as they promote oxidative stress conditions. The aim of our study was to examine the effects of ethanolic extract of propolis (EEP) against copper-induced neuronal damage. In cultured P19 neuronal cells, EEP exacerbated copper-provoked neuronal cell death by increasing the generation of reactive oxygen species (ROS) and through the activation of caspase-3/7 activity. EEP augmented copper-induced up-regulation of p53 and Bax mRNA expressions. Neurotoxic effects of EEP were accompanied by a strong induction of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression and decrease in the expression of c-fos mRNA. SB203580, an inhibitor of p38 mitogen-activated protein kinase (MAPK) prevented detrimental effects of EEP, whereas SP600125, an inhibitor of c-Jun N-terminal kinase (JNK), exacerbated EEP-induced neuronal cell death. Quercetin, a polyphenolic nutraceutical, which is usually present in propolis, was also able to exacerbate copper-induced neuronal death. Our data indicates a pro-oxidative and apoptotic mode of EEP action in the presence of excess copper, wherein ROS/p53/p38 interactions play an important role in death cascades. Our study also pointed out that detailed pharmacological and toxicological studies must be carried out for propolis and other dietary supplements in order to fully recognize the potential adverse effects in specific conditions.