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.

Biosynthesis and characterization of gold nanoparticles using Brazilian red propolis and evaluation of its antimicrobial and anticancer activities

Gold nanoparticles (AuNPs) are highlighted due to their low toxicity, compatibility with the human body, high surface area to volume ratio, and surfaces that can be easily modified with ligands. Biosynthesis of AuNPs using plant extract is considered a simple, low-cost, and eco-friendly approach. Brazilian Red Propolis (BRP), a product of bees, exhibits anti-inflammatory, anti-tumor, antioxidant, and antimicrobial activities. Here, we described the biosynthesis of AuNPs using BRP extract (AuNPextract) and its fractions (AuNPhexane, AuNPdichloromethane, AuNPethyl acetate) and evaluated their structural properties and their potential against microorganisms and cancer cells. AuNPs showed a surface plasmon resonance (SPR) band at 535 nm. The sizes and morphologies were influenced by the BRP sample used in the reaction. FTIR and TGA revealed the involvement of bioactive compounds from BRP extract or its fractions in the synthesis and stabilization of AuNPs. AuNPdichloromethane and AuNPhexane exhibited antimicrobial activities against all strains tested, showing their efficacy as antimicrobial agents to treat infectious diseases. AuNPs showed dose-dependent cytotoxic activity both in T24 and PC-3 cells. AuNPdichloromethane and AuNPextract exhibited the highest in vitro cytotoxic effect. Also, the cytotoxicity of biogenic nanoparticles was induced by mechanisms associated with apoptosis. The results highlight a potential low-cost green method using Brazilian red propolis to synthesize AuNPs, which demonstrated significant biological properties.

Cytotoxic and apoptotic effects of ethanolic propolis extract on C6 glioma cells

Propolis is a natural resinous substance obtained from beehives, and emerging evidence supports that it has antitumor, antiinflammatory, antioxidant, and antimicrobial activities. The aim of the study is to examine the cytotoxic, antioxidant, and apoptotic features of ethanolic propolis extract (PE) on C6 glioma cells. The cells were treated with ethanolic PE at various concentrations for 24 hours, after which the total antioxidant status (TAS) and total oxidant status; malondialdehyde, protein carbonyl, 8-hydroxy-2'-deoxyguanosine, and glutathione (GSH) levels; Cu/Zn-superoxide dismutase (Cu/Zn-SOD) activity; and apoptotic markers were measured. Ethanolic PE at 100, 250, and 500 μg/mL concentrations showed optimal activity on C6 glioma cells. TAS and GSH levels were significantly increased in C6 glioma cells treated with 100 and 500 μg/mL PE compared to control cells (P < .05). Similarly, the activity of Cu/Zn-SOD was higher in C6 glioma cells treated with 250 or 500 μg/mL ethanolic PE compared to control cells (P < .05), as was the caspase-3 mRNA expression level. The highest levels of caspase-8 and -9 expression were in C6 glioma cells treated with 500 μg/mL PE. Collectively, our results indicate that ethanolic PE has cytotoxic and apoptotic effects on C6 glioma cells. Furthermore, it may provide a protective role in the antioxidant defense system. PE shows potential for development as a natural antioxidant and apoptotic agent for the treatment of brain tumors.

Cytotoxic Activity of Six Samples of Brazilian Propolis on Sea Urchin (Lytechinus variegatus) Eggs

The cytotoxic activities of extracts of four samples of propolis from the state of Minas Gerais (Southeast Brazil) and two from the state of Paraná (South Brazil) were evaluated using sea urchin (Lytechinus variegatus) eggs. Cytotoxic activity was observed, characterized mainly by the inhibition of the first cleavage of newly fertilized eggs. Methanol extracts at 32 µg mL⁻¹ of all samples were highly active (97–100%). Extracts were also prepared by successive treatments of the samples with hexane, chloroform, ethyl acetate, and methanol. High activity was observed using the ethyl acetate fractions of all samples, but hexane and chloroform fractions of some samples also had high activity. Based on the chemical composition of the extracts and fractions (published previously), it is hypothesized that the cytotoxic activities observed are due mainly to artepillin C, p-coumaric acid, and kaempferide. The results suggest that caffeoylquinic acids have no cytotoxic activity in sea urchin eggs.

Potential Anti-Cancer Activities of Furanodiene, A Sesquiterpene from Curcuma wenyujin

Furanodiene is a sesquiterpene extracted from the essential oil of the rhizome of Curcuma wenyujin Y.H. Chen et C. Ling (Wen Ezhu). Furanodiene is the primary component in Wen Ezhu's essential oil, accounting for more than 20% by weight. In vitro, MTT assay was used to compare the inhibitory effects of furanodiene and Wen Ezhu's essential oil on 11 human cancer cell lines. Compared to the essential oil, furanodiene showed stronger growth inhibitions on Hela, Hep-2, HL-60, PC3, SGC-7901 and HT-1080 cells with IC50 between 0.6–4.8 μg/ml. In vivo, furanodiene was also found to exhibit inhibitory effects on the growth of uterine cervical (U14) and sarcoma 180 (Sl80) tumors in mice. Our data suggests that furanodiene, an active component from the essential oil of Wen Ezhu, possesses efficacy against uterine cervical cancer.

Assessing the anti-tumour properties of Iraqi propolis in vitro and in vivo

The study was designed to evaluate anti-tumour properties of Iraqi propolis collected from Mosul region (M) on HL-60 and HCT-116 cell lines and on HCT-116 in vivo. M induced an inhibitory effect against the proliferation of HL-60 and colony potential of HCT-116 cells. The apoptosis in HL-60 cells was associated with down-regulation of Bcl-2 and activation of Bax, while in HCT-116 cells, necrotic features were observed; size of cells was dramatically increased by swelling of cytoplasm and loss of membrane integrity, cell rupture and release of cellular contents. Analysis of BrdU/DNA cell cycle in both cell lines showed that M induced cell cycle perturbations in both BrdU positive and BrdU negative cells. The exposure of HL-60 to M caused γ-H2AX in a dose dependent manner and was associated with induction of apoptosis. The experiments in HCT-116 tumor-bearing mice showed that oral administration of propolis at doses that caused no detectable toxicity was associated with a decrease in mitotic cells and an increase in endoreduplications, increased p53 and decreased Ki-67 expression of cells in tumor sections. This study provides the rationale to investigate the potential beneficial effect of propolis in the diet of patients receiving anti-cancer therapies.

Cytotoxic constituents of propolis inducing anticancer effects: a review

Objectives

Propolis is a honeybee product used extensively in traditional medicine for its antioxidant, anti-inflammatory, immunomodulatory and anticancer effects. Propolis exhibits a broad spectrum of biological activities because it is a complex mixture of natural substances. In this review, the antitumour effects of propolis extracts and its constituents (e.g. flavonoids, terpenes and caffeic acid phenethyl ester) are discussed.

Key findings

The effect of propolis on experimental carcinogenesis is discussed, as well as its possible mechanisms of action against tumours, involving apoptosis, cell cycle arrest and interference on metabolic pathways. Propolis seems to be efficient against different tumour cells both in vitro and in vivo, which suggests its potential in the development of new anticancer drugs.

Summary

Propolis extracts may be important economically and would allow a relatively inexpensive cancer treatment. Preclinical investigations are needed to further elucidate the benefits of propolis and its antitumour properties.

Simultaneous Quantification of Eight Major Bioactive Phenolic Compounds in Chinese Propolis by High-Performance Liquid Chromatography

A simple, sensitive and specific high-performance liquid chromatography-UV (HPLC-UV) method has been developed to simultaneously quantify the eight major bioactive phenolic compounds in Chinese propolis, namely caffeic acid, isoferulic acid, 3,4-dimethoxycinnamic acid, pinobanksin 5-methyl ether, pinocembrin, benzyl caffeate, chrysin and galangin. This HPLC assay was performed on an Agilent Zorbax Extend-C18 (250 × 4.6 mm, 5 μm) column with a gradient of methanol and 0.2% aqueous acetic acid (v/v) in 50 min, at a flow rate of 1.0 mL/min, and detected at 290 nm. All calibration curves showed good linearity (r2 >0.999) within the test ranges. The intra- and inter-day assay precision (RSD) of eight phenolic compounds were in the range of 0.07-4.92%. The recoveries were between 98.3% and 104.8%. This assay was applied to the evaluation of nineteen samples from different origins in China. The results indicated that the developed assay could be readily utilized for the quality control of propolis.