Propolis from the Stingless Bee Trigona incisa from East Kalimantan, Indonesia, Induces In Vitro Cytotoxicity and Apoptosis in Cancer Cell lines

Uncovering the anti-breast cancer activity potential of east Kalimantan propolis by In vitro and bioinformatics analysis

Numerous side effects of breast cancer drugs have prompted researchers to explore more into new therapeutic approaches derived from natural substances. In this context, our study focused on uncovering the potential of East Kalimantan propolis from Trigona apicalis for breast cancer treatment including the underlying mechanisms through bioinformatics approached. We conducted integrated in vitro and bioinformatics analysis of network pharmacology, molecular docking, molecular dynamics and MM-GBSA analysis. Initially, in vitro cytotoxic assay demonstrated the anti-breast cancer activity potential of ethanol extract of East Kalimantan propolis, particularly its ethyl acetate fraction, which exhibited similar activity to doxorubicin, as indicated by their IC50 value. This study revealed eight propolis compounds, consisting of flavonoids and phenolic acids, in East Kalimantan propolis. By integrating microarray datasets (GSE29431, GSE36295, and GSE42568) analysis with potential targets derived from propolis compounds, 39 shared target genes were identified. Subsequently, GO and KEGG pathway, protein-protein interaction (PPI) network, core hub genes and gene expression analysis revealed three major targets, namely, PTGS2, CXCL2, and MMP9. Among them, only MMP9 was highly expressed in breast cancer than normal. Moreover, molecular docking revealed the six of propolis compounds which exhibited pronounced binding affinity towards MMP-9, better than marimastat as control drug. Dynamic simulation confirmed the stability of chrysin and quercetin as best compounds. Additionally, MM-GBSA analysis revealed a relative binding energy for chrysin (-25.6403 kcal/mol) that was comparable to marimastat (-27.3827 kcal/mol). In conclusion, this study reveals how East Kalimantan Propolis affect breast cancer and emphasizes MMP9 as a key target for future therapeutics.

Exploring the Functional Properties of Propolis, Geopropolis, and Cerumen, with a Special Emphasis on Their Antimicrobial Effects

Bee propolis has been touted as a natural antimicrobial agent with the potential to replace antibiotics. Numerous reports and reviews have highlighted the functionalities and applications of the natural compound. Despite much clamor for the downstream application of propolis, there remain many grounds to cover, especially in the upstream production, and factors affecting the quality of the propolis. Moreover, geopropolis and cerumen, akin to propolis, hold promise for diverse human applications, yet their benefits and intricate manufacturing processes remain subjects of intensive research. Specialized cement bees are pivotal in gathering and transporting plant resins from suitable sources to their nests. Contrary to common belief, these resins are directly applied within the hive, smoothed out by cement bees, and blended with beeswax and trace components to create raw propolis. Beekeepers subsequently harvest and perform the extraction of the raw propolis to form the final propolis extract that is sold on the market. As a result of the production process, intrinsic and extrinsic factors, such as botanical origins, bee species, and the extraction process, have a direct impact on the quality of the final propolis extract. Towards the end of this paper, a section is dedicated to highlighting the antimicrobial potency of propolis extract.

The Role of Propolis as a Natural Product with Potential Gastric Cancer Treatment Properties: A Systematic Review

Gastric cancer is one of the most common, aggressive, and invasive types of malignant neoplasia. It ranks fifth for incidence and fourth for prevalence worldwide. Products of natural origin, such as propolis, have been assessed for use as new complementary therapies to combat cancer. Propolis is a bee product with antiproliferative and anticancer properties. The concentrations and types of secondary metabolites contained in propolis mainly vary according to the geographical region, the season of the year, and the species of bees that make it. The present study is a systematic review of the main articles related to the effects of propolis against gastric cancer published between 2011 and 2021 in the PubMed and Science Direct databases. Of 1305 articles published, only eight studies were selected; among their principal characteristics was the use of in vitro analysis with cell lines from gastric adenocarcinoma and in vivo murine models of the application of propolis treatments. These studies suggest that propolis arrests the cell cycle and inhibits proliferation, prevents the release of oxidizing agents, and promotes apoptosis. In vivo assays showed that propolis decreased the number of tumors by regulating the cell cycle and the expression of proteins related to apoptosis.

Molecular Docking Studies on Methanolic Propolis Extracts Collected from Different Regions in Saudi Arabia as a Potential Inhibitor of Topoisomerase IIβ

Propolis is a sticky substance made by honeybees from various plant parts that is rich in biologically active substances such as flavonoids, phenolic acids, and phenolics and has a wide range of applications in the food, cosmetics, and pharmaceutical industries. The current study focused on the isolation of honeybee propolis samples from three different locations in Saudi Arabia: Al Hada, Baljurashi, and Rawdat Khuraim, and the evaluation of their anti-cancer effect against human liver cancer cell lines (HeP-G2) and human breast cancer cell lines (MCF-7). Five chemical compounds present in the methanolic extract of propolis honeybee were detected by HPLC. Furthermore, molecular modeling studies were conducted to explain the mechanism of anti-cancer activity exerted by the active compounds. The propolis samples collected from the three isolation sites had anti-cancer activity against MCF-7 and HeP-G2. Samples collected from the Rawdat Khuraim site showed the highest inhibitory activity reaching 81.5% and 83.2% against MCF-7 and HeP-G2, respectively. HPLC detected four main active compounds from propolis samples: pinobanksin, pinocembrin, galangin, and xanthomicrol. The molecular docking technique showed that galangin and pinocembrin had higher anti-cancer activity than xanthomicrol and pinobanksin as the binding affinity of galangin and pinocembrin with the active sites of the topoisomerase IIβ enzyme was much greater.

The Potential Use of Propolis as a Primary or an Adjunctive Therapy in Respiratory Tract-Related Diseases and Disorders: A Systematic Scoping Review

Propolis is a resinous beehive product that is collected by the bees from plant resin and exudates, to protect and maintain hive homeostasis. Propolis has been used by humans therapeutically to treat many ailments including respiratory tract-related diseases and disorders. The aim of the present systematic scoping review is to evaluate the experimental evidence to support the use of propolis as a primary or an adjunctive therapy in respiratory tract-related diseases and disorders. After applying the exclusion criteria, 158 research publications were retrieved and identified from Scopus, Web of Science, Pubmed, and Google Scholar. The key themes of the included studies were pathogenic infection-related diseases and disorders, inflammation-related disorders, lung cancers, and adverse effects. Furthermore, the potential molecular and biochemical mechanisms of action of propolis in alleviating respiratory tract-related diseases and disorders are discussed. In conclusion, the therapeutic benefits of propolis have been demonstrated by various in vitro studies, in silico studies, animal models, and human clinical trials. Based on the weight and robustness of the available experimental and clinical evidence, propolis is effective, either as a primary or an adjunctive therapy, in treating respiratory tract-related diseases.

Cytotoxicity effect of honey, bee pollen, and propolis from seven stingless bees in some cancer cell lines

Our effort to find new material for anti cancer from natural resources leads us to focus on stingless bee products such as honey, bee pollen, and propolis. The products were from seven stingless bees named Homotrigona fimbriata, Heterotrigona itama, Heterotrigona bakeri, Tetragonula sarawakensis, Tetragonula testaceitarsis, Tetragonula fuscobalteata, Tetragonula laeviceps. The stingless bee products were evaluated for their cytotoxicity effect on MCF-7, HeLa and Caco-2 cancer cell lines. This is the first time to be reported that the honey, ethanol extracts of bee pollen and propolis of H. fimbriata displayed more potent cytotoxicity than other stingless bee products. By chromatography and biological activity-guided fractionation, ethanol extract of propolis from H. fimbriata was fractionated and isolated its active compound named mangiferonic acid. Mangiferonic acid showed a cytotoxicity effect with IC₅₀ values 96.76 µM in MCF-7, >110.04 µM in HeLa, and > 110.04 µM in Caco-2, respectively. These results exhibited the potential of ethanol extracts from propolis of H. fimbriata to be further developed for drug and experiments to verify the function are essential.

Use of Stingless Bee Propolis and Geopropolis against Cancer-A Literature Review of Preclinical Studies

Cancer is one of the major maladies affecting humankind and remains one of the leading causes of death worldwide. The investigation of the biological activities of stingless bee products, especially propolis and geopropolis, has revealed promising therapeutic properties, especially in the research on new antineoplastic agents. This literature review of preclinical trials, involving biological assays of antitumor activity and identification of the chemical composition of propolis and geopropolis of stingless bee species, describes the cytotoxicity in tumor lineages (breast, lung, ovarian, liver, mouth, pharynx, larynx, colon, stomach, colorectal, cervix, kidney, prostate, melanoma, human glioblastoma, canine osteosarcoma, erythroleukemia, human chronic myelocytic leukemia, and human promyelocytic leukemia) of propolis and geopropolis of 33 species of stingless bees. The chemical composition of propolis and geopropolis was identified, indicating that these belong to the chemical classes of phenolic acids, flavonoids, coumarins, benzophenones, anthraquinones, alkaloids, terpenes, steroids, saponins, fatty acids, and carbohydrates and are possibly responsible for the cytotoxicity in tumor cells. Apoptosis was one of the main mechanisms of cytotoxicity of extracts and substances isolated from stingless bee products. Although the results found are encouraging, other preclinical studies and clinical trials are essential for the discovery of new anticancer agents.

Stingless Bee Propolis: New Insights for Anticancer Drugs

Natural products are important sources of biomolecules possessing antitumor activity and can be used as anticancer drug prototypes. The rich biodiversity of tropical and subtropical regions of the world provides considerable bioprospecting potential, including the potential of propolis produced by stingless bee species. Investigations of the potential of these products are extremely important, not only for providing a scientific basis for their use as adjuvants for existing drug therapies but also as a source of new and potent anticancer drugs. In this context, this article organizes the main studies describing the anticancer potential of propolis from different species of stingless bees with an emphasis on the chemical compounds, mechanisms of action, and cell death profiles. These mechanisms include apoptotic events; modulation of BAX, BAD, BCL2-L1 (BCL-2 like 1), and BCL-2; depolarization of the mitochondrial membrane; increased caspase-3 activity; poly (ADP-ribose) polymerase (PARP) cleavage; and cell death induction by necroptosis via receptor interacting protein kinase 1 (RIPK1) activation. Additionally, the correlation between compounds with antioxidant and anti-inflammatory potential is demonstrated that help in the prevention of cancer development. In summary, we highlight the important antitumor potential of propolis from stingless bees, but further preclinical and clinical trials are needed to explore the selectivity, efficacy, and safety of propolis.

Plant metabolite 5-pentadecyl resorcinol is produced by the Amazonian fungus Penicillium sclerotiorum LM 5679

Since the classic studies of Alexander Flemming, Penicillium strains have been known as a rich source of antimicrobial substances. Recent studies have identified novel metabolites produced by Penicillium sclerotiorum that have antibacterial, antifouling and pharmaceutical activities. Here, we report the isolation of a P. sclerotiorum (LM 5679) from Amazonian soil and carry out a culture-based study to determine whether it can produce any novel secondary metabolite(s) that are not thus-far reported for this genus. Using a submerged culture system, secondary metabolites were recovered by solvent extract followed by thin-layer chromatography, nuclear magnetic resonance, and mass spectroscopy. One novel secondary metabolite was isolated from P. sclerotiorum (LM 5679); the phenolic compound 5-pentadecyl resorcinol widely known as an antifungal, that is produced by diverse plant species. This metabolite was not reported previously in any Penicillium species and was only found once before in fungi (that time, in a Fusarium). Here, we discuss the known activities of 5-pentadecyl resorcinol in the context of its mode-of-action as a hydrophobic (chaotropicity-mediated) stressor.

Propolis of stingless bees: A phytochemist's guide through the jungle of tropical biodiversity

BACKGROUND

Stingless bees (Meliponini), like honeybees Apis mellifera, collect plant resins in order to produce propolis (cerumen, geopropolis). This type of propolis has long been used in traditional medicine in Mexico, Brazil, Argentina, India, and Vietnam, as a remedy for improving health and treating various diseases. The scientific and commercial interest in stingless bee propolis has been steadily increasing over the last few years. The new and growing knowledge in this field requires systematising, as a basis for further work. Recent reviews of Meliponini propolis deal only with the South American and Mesoamerican species, while reviews of the Asian, Australian and African species are missing. Furthermore, the chemical composition has not been thoroughly reviewed since 2007.

PURPOSE

This review summarises and discusses the available data about the chemical composition of propolis from the stingless bee species (Meliponinae) of the Americas, Asia and Australia, published after 2007. The published information on the biological action of chemically characterised Meliponini propolis, and of individual constituents, is addressed. The plant sources of this propolis are also considered.

CONCLUSION AND PERSPECTIVES

Chemical studies of Meliponini propolis has resulted in the discovery of new natural molecules, some of them with valuable bioactivity. Moreover, finding known molecules in propolis stimulates the study of their pharmacological properties. The enormous chemical variability of stingless bee propolis is a challenge to chemists, entomologists and pharmacologists. It is essential to perform pharmacological studies with only chemically characterised propolis of stingless bees. Further studies are required to chemically characterise and scientifically support the medicinal properties of stingless bee propolis and to clarify the potential for its commercial use. This could lead to increased prices for Meliponinae propolis and provide an additional source of income for farmers in rural communities with most serious social needs.

The Isorhamnetin-Containing Fraction of Philippine Honey Produced by the Stingless Bee Tetragonula biroi Is an Antibiotic against Multidrug-Resistant Staphylococcus aureus

Honey exhibits antibacterial and antioxidant activities that are ascribed to its diverse secondary metabolites. In the Philippines, the antibacterial and antioxidant activities, as well as the bioactive metabolite contents of the honey, have not been thoroughly described. In this report, we investigated the in vitro antibacterial and antioxidant activities of honey from Apis mellifera and Tetragonula biroi, identified the compound responsible for the antibacterial activity, and compared the observed bioactivities and metabolite profiles to that of Manuka honey, which is recognized for its antibacterial and antioxidant properties. The secondary metabolite contents of honey were extracted using a nonionic polymeric resin followed by antibacterial and antioxidant assays, and then spectroscopic analyses of the phenolic and flavonoid contents. Results showed that honey extracts produced by T. biroi exhibits antibiotic activity against Staphylococcal pathogens as well as high antioxidant activity, which are correlated to its high flavonoid and phenolic content as compared to honey produced by A. mellifera. The bioassay-guided fractionation paired with Liquid Chromatography Mass Spectrometry (LCMS) and tandem MS analyses found the presence of the flavonoid isorhamnetin (3-methylquercetin) in T. biroi honey extract, which was demonstrated as one of the compounds with inhibitory activity against multidrug-resistant Staphylococcus aureus ATCC BAA-44. Our findings suggest that Philippine honey produced by T. biroi is a potential nutraceutical that possesses antibiotic and antioxidant activities.

Lessons from Exploring Chemical Space and Chemical Diversity of Propolis Components

Propolis is a natural resinous material produced by bees and has been used in folk medicines since ancient times. Due to it possessing a broad spectrum of biological activities, it has gained significant scientific and commercial interest over the last two decades. As a result of searching 122 publications reported up to the end of 2019, we assembled a unique compound database consisting of 578 components isolated from both honey bee propolis and stingless bee propolis, and analyzed the chemical space and chemical diversity of these compounds. The results demonstrated that both honey bee propolis and stingless bee propolis are valuable sources for pharmaceutical and nutraceutical development.

Antioxidant-Based Medicinal Properties of Stingless Bee Products: Recent Progress and Future Directions

Stingless bees are a type of honey producers that commonly live in tropical countries. Their use for honey is being abandoned due to its limited production. However, the recent improvements in stingless bee honey production, particularly in South East Asia, have brought stingless bee products back into the picture. Although there are many stingless bee species that produce a wide spread of products, known since old eras in traditional medicine, the modern medical community is still missing more investigational studies on stingless bee products. Whereas comprehensive studies in the current era attest to the biological and medicinal properties of honeybee (Apis mellifera) products, the properties of stingless bee products are less known. This review highlights for the first time the medicinal benefits of stingless bee products (honey, propolis, pollen and cerumen), recent investigations and promising future directions. This review emphasizes the potential antioxidant properties of these products that in turn play a vital role in preventing and treating diseases associated with oxidative stress, microbial infections and inflammatory disorders. Summarizing all these data and insights in one manuscript may increase the commercial value of stingless bee products as a food ingredient. This review will also highlight the utility of stingless bee products in the context of medicinal and therapeutic properties, some of which are yet to be discovered.

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.

Propolis extract protects against radiation-induced intestinal mucositis through anti-apoptotic mechanisms

Intestinal mucositis is a common side effect during radiotherapy that could be largely prevented by compounds possessing anti-inflammatory or anti-oxidant properties, including extracts of propolis containing a high proportion of flavonoids. A specially formulated aqueous extract of propolis (PWE) has been prepared in such a way to preclude the inclusion of flavonoids but contain mostly organic aromatic acids to study whether it would still protect against radiation-induced intestinal mucositis and to study the possible involvement of apoptotic pathways. Rats were exposed to a gamma radiation dose of 8 Gy from a Cesium-137 source in order to inflict intestinal mucositis. Three days before exposure, rats were given PWE orally and treatment continued for 2 more days. Twenty-four hours later, rats were sacrificed, the small intestine was excised, and sections were examined histologically. Different parameters for apoptosis, inflammation, and oxidative stress were determined in the serum and in intestinal homogenates. Radiation exposure led to histological and biochemical signs of intestinal damage. This was associated with an increase in apoptotic indicators and derangement in oxidative stress parameters. All deranged parameters were largely prevented by PWE. The findings provide evidence that the protective effect of PWE against intestinal radiation damage involves not only its anti-inflammatory and anti-oxidant effects but also its anti-apoptotic properties as well.

Cardol triene inhibits dengue infectivity by targeting kl loops and preventing envelope fusion

Dengue virus causes a global burden that specific chemotherapy has not been established. A previous report suggested that anacardic acid inhibited hepatitis C virus infection. Here, we explored structure activity relationship of anacardic acid, cardanol, and cardol homologues with anti-DENV cellular infectivities. Cardol triene showed the highest therapeutic index at 29.07 with the CC₅₀ and EC₅₀ of 207.30 ± 5.24 and 7.13 ± 0.72 µM, respectively. Moreover, we observed that the more unsaturated the hydrocarbon tail, the higher the CC₅₀s in all head groups. High CC₅₀s were also found in HepG-2, THP-1, and HEK-293 cell lines where cardol triene CC₅₀s were 140.27 ± 8.44, 129.77 ± 12.08, and 92.80 ± 3.93 µM, respectively. Cardol triene expressed pan-dengue inhibition with the EC₅₀s of 5.35 to 8.89 µM and kl loops of dengue envelope proteins were major targets. The strong binding energy at T48, E49, A50, P53, K128, V130, L135, M196, L198, Q200, W206, L207, I270, and L277 prevented cellular pH-dependent fusion. Zika virus kl loops were aligned in the closed position preventing cardol triene to bind and inhibit fusion and infectivity. This study showed for the first time that cardol triene had a potential for further development as anti-dengue inhibitors.

Molecular mechanism of cardol, isolated from Trigona incisa stingless bee propolis, induced apoptosis in the SW620 human colorectal cancer cell line

Background

Cardol is a major bioactive constituent in the Trigona incisa propolis from Indonesia, with a strong in vitro antiproliferative activity against the SW620 colorectal adenocarcinoma cell line (IC₅₀ of 4.51 ± 0.76 μg/mL). Cardol induced G₀/G₁ cell cycle arrest and apoptotic cell death. The present study was designed to reveal the mechanism of cardol’s antiproliferative effect and induction of apoptosis.

Methods

Changes in cell morphology were observed by light microscopy. To determine whether the mitochondrial apoptotic pathway was involved in cell death, caspase-3 and caspase-9 activities, western blot analysis, mitochondrial membrane potential, and intracellular reactive oxygen species (ROS) levels were assayed.

Results

Changes in the cell morphology and the significantly increased caspase-3 and caspase-9 activities, plus the cleavage of pro-caspase-3, pro-caspase-9 and PARP, supported that cardol caused apoptosis in SW620 cells within 2 h after treatment by cardol. In addition, cardol decreased the mitochondrial membrane potential while increasing the intracellular ROS levels in a time- and dose-dependent manner. Antioxidant treatment supported that the cardol-induced cell death was dependent on ROS production.

Conclusion

Cardol induced cell death in SW620 cells was mediated by oxidative stress elevation and the mitochondrial apoptotic pathway, and these could be the potential molecular mechanism for the antiproliferative effect of cardol.