Cerumen of Australian stingless bees (Tetragonula carbonaria): gas chromatography-mass spectrometry fingerprints and potential anti-inflammatory properties

Rosin: A comprehensive review on traditional uses, phytochemistry, and pharmacology

Rosin, a natural resin obtained from conifer trees, has a long history of use in traditional folk medicine for treating abscesses, wounds, carbuncles, and burns, etc. It has been employed in ancient Egypt, China, Nordic countries, and Turkey as a therapeutic remedy. This comprehensive review examines the traditional uses, phytochemistry, and pharmacology of rosin, and it provides a critical update on current knowledge of rosin and identifies potential therapeutic opportunities. The chemical composition of rosin is known to vary depending on factors such as botanical sources, geographical locations, and processing methods. Rosin acids, which account for over 90% of its primary chemical constituents, have been identified as the predominant compounds in rosin. Researchers have isolated approximately 50 compounds from rosin, with terpenoid rosin acids being the most prevalent. Furthermore, the review highlights the potential pharmacological activities of rosin and its constituents. Crude extracts and isolated rosin acids have demonstrated promising properties, including antimicrobial, anti-inflammatory, anti-tumor, insecticidal, wound healing, and anti-obesity effects. However, the review emphasizes that further research is needed, as existing studies are predominantly preliminary. Many of the reported bioactivities require further verification, and the underlying mechanisms of action remain largely unexplored. In conclusion, rosin has been extensively used in traditional medicine across different cultures, and its chemical composition has been confirmed to a significant extent. The pharmacological activities observed in crude extracts and isolated rosin acids support its traditional uses. Nevertheless, additional research is necessary to deepen our understanding of the pharmacological mechanisms underlying its effects.

Differences in the biochemical content and radical scavenging activity of propolis from different parts of a Meliponula ferruginea hive

Research on stingless bee products has increased in recent years, and of particular interest is propolis because of its biological activities such as antioxidant and antimicrobial. However, there is paucity of information regarding intra-hive variations in the biochemical composition and biofunctional properties of this propolis. In this study, we investigated the phytochemicals and radical scavenging activity (RSA) of Meliponula ferruginea propolis from 10 wooden hives (n = 49). The samples were collected from five different locations comprising the entrance, involucrum, pillars, pots and sealant. Principal component analysis showed that there is an intra-hive variation in phytochemical content and RSA. Phenolic content constituted the highest phytochemical content in all the locations. The sealant and entrance had the highest amounts of phytochemicals compared to the involucrum, pillars and pots. Further analysis of propolis extracts by gas chromatography-mass spectrometry revealed occurrence of different compounds such as monoterpenoids, hydrocarbons, triterpenoids and alkaloids. Hydrocarbons were common in all parts while monoterpenes and triterpenes were present in the entrance. The findings of our study indicates that there is an intra-hive variation in propolis of M. ferruginea and hence this information will provide further insight into better understanding of stingless bee propolis.

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.

Terpene-Containing Analogues of Glitazars as Potential Therapeutic Agents for Metabolic Syndrome

Metabolic syndrome is a complex of abnormalities involving impaired glucose and lipid metabolism, which needs effective pharmacotherapy. One way to reduce lipid and glucose levels associated with this pathology is the simultaneous activation of nuclear PPAR-alpha and gamma. For this purpose, we synthesized a number of potential agonists based on the pharmacophore fragment of glitazars with the inclusion of mono- or diterpenic moiety in the molecular structure. The study of their pharmacological activity in mice with obesity and type 2 diabetes mellitus (C57Bl/6^Ay) revealed one substance that was capable of reducing the triglyceride levels in the liver and adipose tissue of mice by enhancing their catabolism and expressing a hypoglycemic effect connected with the sensitization of mice tissue to insulin. It has also been shown to have no toxic effects on the liver.

A review of stingless bees' bioactivity in different parts of the world

Stingless bees, also known as meliponines, live in beehives. However, reports on the distribution of stingless bees are scattered, resulting in a lack of precision. Honey and propolis are the main components that can be harvested from their beehive, with a great commercial value of up to 610 million USD. Despite the enormous potential profits, discrepancies in their bioactivities have been observed worldwide, leading to a lack of confidence. Therefore, this review provided oversight on the potential of stingless bee products and highlighted the differences between stingless bees in Asia, Australia, Africa, and America. The bioactivity of stingless bee products is diverse and exhibits great potential as an antimicrobial agent or in various diseases such as diabetes, cardiovascular disease, cancers, and oral problems.

Synergic Effect of Honey with Other Natural Agents in Developing Efficient Wound Dressings

Honey has been used for therapeutic and nutritional purposes since ancient times. It was considered one of the essential medical assets in wound healing. According to research, honeybees have significant antibacterial, antioxidant, anti-inflammatory, antitumor, and wound-healing properties. Lately, scientific researchers have focused on apitherapy, using bee products to protect and strengthen the immune system. Since honey is the most important natural product rich in minerals, proteins, and vitamins, it has been intensively used in such therapies. Honey has gained significant consideration because of the beneficial role of its antioxidant compounds, such as enzymes, proteins, amino and organic acids, polyphenols, and carotenoids, but mainly due to flavonoids and phenolic acids. It has been proven that phenolic compounds are responsible for honey's biological activity and that its physicochemical properties, antioxidants, and antimicrobial potential are significant for human health. The review also presents some mechanisms of action and the medical applications of honey, such as wound healing dressings, skin grafts, honey-based nanofibers, and cochlear implants, as the most promising wound healing tools. This extensive review has been written to highlight honey's applications in medicine; its composition with the most important bioactive compounds also illustrates its synergistic effect with other natural products having remarkable therapeutic properties in wound healing.

Pollen preferences of stingless bees in the Amazon region and southern highlands of Ecuador by scanning electron microscopy and morphometry

Stingless bees are effective pollinators of native tropical flora. Their environmental service maintains flow of pollen through pollination, increase reproductive success and influence genetic structure in plants. The management of stingless bees “meliponiculture”, is an activity limited to the countryside in Ecuador. The lack of knowledge of their managers about pollen resources can affect the correct maintenance/production of nests. The objective is to identify botanical families and genera of pollen grains collected by stingless bees by morphological features and differentiate potential species using geometric morphometry. Thirty-six pot pollen samples were collected from three Ecuadorian provinces located in two climatically different zones. Pollen type identification was based on the Number, Position, Character system. Using morphological features, the families and genera were established. Morphometry landmarks were used to show variation for species differentiation. Abundance, diversity, similarity and dominance indices were established by counting pollen grains, as well as spatial distribution relationships by means of Poisson regression. Forty-six pollen types were determined in two study areas, classified into 27 families and 18 genera. In addition, it was possible to identify more than one species, classified within the same family and genus, thanks to morphometric analysis. 1148 ± 799 (max 4211; min 29) pollen grains were counting in average. The diversity showed a high richness, low dominance and similarity between pollen resources. Families Melastomataceae and Asteraceae, genera Miconia and Bidens, were found as the main pollen resources. The stingless bee of this study are mostly generalist as shown the interaction network. The results of the present survey showed that stingless bees do not collect pollen from a single species, although there is evidence of a predilection for certain plant families. The diversity indexes showed high richness but low uniformity in the abundance of each family identified. The results of the study are also meaningful to the meliponiculture sector as there is a need to improve management practices to preserve the biodiversity and the environment.

Anti-Fibrotic Potential of Tomentosenol A, a Constituent of Cerumen from the Australian Native Stingless Bee, Tetragonula carbonaria

Bioactivity-guided fractionation was used to isolate two compounds, tomentosenol A (1) and torellianone A (2), from a cerumen extract from Tetragonula carbonaria. The anti-fibrotic activity of these compounds was examined using human cultured neonatal foreskin fibroblasts (NFF) and immortalised keratinocytes (HaCaTs). Tomentosenol A (1), inhibited NFF and HaCaT cell proliferation and prevented NFF and HaCaT scratch wound repopulation at 12.5-25 µM concentrations. These inhibitory effects were associated with reduced cell viability, determined by tetrazolium dye (MTT) and sulforhodamine B (SRB) assays. Compound 1 further inhibited transforming growth factor-β₁ (TGF-β₁)-stimulated, NFF-myofibroblast differentiation and soluble collagen production; and was an effective scavenger of the model oxidant, 2,2-diphenyl-1-picrylhydrazyl (DPPH·), with an EC₅₀ value of 44.7 ± 3.1 µM. These findings reveal significant anti-fibrotic potential for cerumen-derived tomentosenol A (1).

Effect of Honey on Pediatric Radio/Chemotherapy-Induced Oral Mucositis (R/CIOM): A Systematic Review and Meta-Analysis

Background

As a common side effect of radio/chemotherapy, oral mucositis severely affects patients' quality of life. Honey has been recommended for adults with radio/chemotherapy-induced oral mucositis (R/CIOM), but its effect for pediatric patients has not been systematically evaluated. Therefore, the aim of this systematic review and meta-analysis was to illuminate whether honey is effective in treating pediatric R/CIOM.

Methods

Two authors searched electronic databases including PubMed, Embase, the Cochrane Library, Web of Science, and Scopus to identify relevant studies, published in English. Then, the outcomes data was extracted from eligible studies and pooled in the meta-analysis.

Results

Totally, five studies containing 316 patients were included in our systematic review and meta-analysis. The result indicated that honey intervention significantly reduced the recovery time (MD = −5.10, 95% CI [−9.60, −0.61], P < 0.001, I² = 98%, random-effect model) in pediatric patients. Honey also reduced the occurrence of all grades of R/CIOM (RR = 0.19, 95% CI [0.12, 0.30], P < 0.001, I² = 0%, fixed-effect model) and the occurrence of grade III and grade IV R/CIOM (RR = 0.18, 95% CI [0.08, 0.41], P < 0.001, I² = 7%, fixed-effect model), and the sensitivity analysis showed the results were stable and robust.

Conclusion

Therefore, honey could be a competent candidate for the complementary treatment of pediatric R/CIOM.

Deacetylated cellulose acetate nanofibrous dressing loaded with chitosan/propolis nanoparticles for the effective treatment of burn wounds

Every year, about 1 out of 9 get burnt in Egypt, with a mortality rate of 37%, and they suffer from physical disfigurement and trauma. For the treatment of second-degree burns, we aim at making a smart bandage provided with control of drug release (using chitosan nanoparticles) to enhance the healing process. This bandage is composed of natural materials; namely, cellulose acetate (CA), chitosan, and propolis (bee resin) as the loaded drug. Cellulose acetate nanofibers were deacetylated by NaOH after optimizing the reaction time and the concentration of NaOH solution, and the product was confirmed with FTIR analysis. Chitosan/propolis nanoparticles were prepared by ion gelation method with size ranging from 100 to 200 nm and a polydispersity index of 0.3. Chitosan/propolis nanoparticles were preloaded in the CA solution to ensure homogeneity. Loaded deacetylated cellulose nanofibers have shown the highest hydrophobicity measured by contact angle. Cytotoxicity of propolis and chitosan/propolis nanoparticles were tested and the experimental IC₅₀ value was about 137.5 and 116.0 μg/mL, respectively, with p-value ≤0.001. In addition, chitosan/propolis nanoparticles loaded into cellulose nanofibers showed a cell viability of 89.46% in the cell viability test. In-vivo experiments showed that after 21 days of treatment with the loaded nanofibers repairing of epithelial cells, hair follicles and sebaceous glands in the skin of the burn wound were found in albino-mice model.

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.

Resin Use by Stingless Bees: A Review

Stingless bees (Meliponini) are highly social bees that are native to tropical and sub-tropical ecosystems. Resin use is vital to many aspects of stingless bee colony function. Stingless bees use resin to build essential nest structures, repel predators, and kill would-be invaders. Furthermore, resin-derived compounds have been found to enrich the cuticular chemical profiles of many stingless bee species, and resin may play an important role in shaping the microbial communities associated with stingless bees and their nests. Despite its importance for colony function, previous reviews of resin use by stingless bees are lacking. This topic grows increasingly urgent as changes in beekeeping and land use practices occur, potentially diminishing stingless bees' ability to incorporate resin into the nest environment. In this article, we review existing literature on resin use by stingless bees and discuss potential areas of future research.

Antiviral, Antibacterial, Antifungal, and Antiparasitic Properties of Propolis: A Review

Propolis is a complex phytocompound made from resinous and balsamic material harvested by bees from flowers, branches, pollen, and tree exudates. Humans have used propolis therapeutically for centuries. The aim of this article is to provide comprehensive review of the antiviral, antibacterial, antifungal, and antiparasitic properties of propolis. The mechanisms of action of propolis are discussed. There are two distinct impacts with regards to antimicrobial and anti-parasitic properties of propolis, on the pathogens and on the host. With regards to the pathogens, propolis acts by disrupting the ability of the pathogens to invade the host cells by forming a physical barrier and inhibiting enzymes and proteins needed for invasion into the host cells. Propolis also inhibits the replication process of the pathogens. Moreover, propolis inhibits the metabolic processes of the pathogens by disrupting cellular organelles and components responsible for energy production. With regard to the host, propolis functions as an immunomodulator. It upregulates the innate immunity and modulates the inflammatory signaling pathways. Propolis also helps maintain the host's cellular antioxidant status. More importantly, a small number of human clinical trials have demonstrated the efficacy and the safety of propolis as an adjuvant therapy for pathogenic infections.

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.

Broad-spectrum pharmacological activity of Australian propolis and metabolomic-driven identification of marker metabolites of propolis samples from three continents

Propolis is a by-product of honeybee farming known for its broad therapeutic benefits around the world and is extensively used in the health food and beverage industry. Despite Australia being one of the world's megadiverse countries with rich flora and fauna, Australian propolis samples have not been explored adequately with most in vitro and in vivo studies centred on their Brazilian and Chinese counterparts. In view of this, our study was designed to investigate the chemical composition and anti-proliferative, antibacterial, antifungal, anti-inflammatory and antioxidant properties of Australian propolis (AP-1) extract to draw a comparison with Brazilian (BP-1) and Chinese propolis (CP-1) extracts. The AP-1 extract displayed significantly greater anti-proliferative activity against the MCF7 and the MDA-MB-231 metastatic breast adenocarcinoma cell lines compared to BP-1 and CP-1 (p < 0.05). Similar trends were also observed in the antibacterial (Escherichia coli and Staphylococcus aureus), anti-inflammatory (lipopolysaccharide-induced RAW264.7 macrophages) and antioxidant assays (ABTS, DPPH and CUPRAC) with AP-1 exhibiting more potent activity than BP-1 and CP-1. The ultra-high performance liquid chromatography (UPLC) coupled with quadrupole high-resolution time of flight mass spectrometry (qTOF-MS) and chemometrics implementing unsupervised PCA and supervised OPLS-DA analyses of the propolis samples from Australia, China and Brazil revealed 67 key discriminatory metabolites belonging to seven main chemical classes including flavonoids, triterpenes, acid derivatives, stilbenes, steroid derivatives, diterpenes and miscellaneous compounds. Additionally, seven common phenolic compounds were quantified in the samples. Further mechanistic studies are necessary to elucidate the modes of action of Australian propolis for its prospective use in the food, nutraceutical and pharmaceutical industries.

Phytochemicals, mineral contents, antioxidants, and antimicrobial activities of propolis produced by Brunei stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami

The present study focused on the evaluation of phytochemical properties, essential mineral elements, and heavy metals contained in raw propolis produced by stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami found in the same ecological conditions and environment in Brunei Darussalam. The results indicated that propolis of the three stingless bee species mainly consisted of lipids (45.60–47.86%) and very low carbohydrate (0.17–0.48%) and protein contents (0.18–1.18%). The propolis was rich in mineral elements, thus good sources of minerals, while they contained low concentrations of all heavy metals. Propolis of the different bee species could be distinguished based on their mineral compositions. The vibrational and absorption spectra suggested that propolis contains π-conjugated aliphatic and aromatic compounds as well as aromatic acids having amine, ester, carbonyl, alkyl, and hydroxyl functional groups which might be attributed to the presence of phenolic and flavonoid compounds. The antioxidant capacity of the propolis, based on radical scavenging activity of their ethanol extract, was in line with their total phenolic content. The ethanol extract of the propolis also showed antimicrobial activities against four bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa). The propolis showed slightly higher antibacterial activity against Gram-positive (B. subtilis and S. aureus) bacteria, indicating that the antimicrobial active compounds could be associated with flavonoids, which were quantified to be approximately comparable in all the propolis.

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.

Antibacterial and antioxidant assessment of cellulose acetate/polycaprolactone nanofibrous mats impregnated with propolis

Cellulose acetate (CA) electrospun nanofibers are one of the most practical cellulosic material which normally applied as carriers for drug delivery and wound healing systems. In this study, CA and polycaprolactone (PCL) was applied to fabricate the electrospun nanofibrous for wound dressing application. Propolis is a resin-like macromolecule produced by honeybees from the buds and diverse plants. Among many applications of this macromolecule, it has been occasionally employed directly to the skin for wound healing applications. Herein, owing to the significance of propolis, CA/PCL nanofibers were impregnated with a propolis-extracted solution to reach antibacterial and antioxidant mat. The scanning electron microscopy (SEM) images revealed that electrospinning of 10% (w/w) CA along with 14% (w/w) PCL produced excellent nanofibers compared to the resultant nanofibers. Hydrophobicity/hydrophilicity nature of CA/PCL mats was measured using water contact-angle method before and after treatment with NaOH. The nanofibrous mats exhibited a high water absorption capacity of about 400%. Antioxidant effect was measured by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay and propolis-CA/PCL presented a high antioxidant activity. Additionally, propolis-CA/PCL mats showed antibacterial activity against both the Gram-positive and Gram-negative bacteria. In conclusion, our results have confirmed that the propolis-impregnated CA/PCL mats have provided an appropriate surface for wound healing system.

Rapid Determination of Major Compounds in the Ethanol Extract of Geopropolis from Malaysian Stingless Bees, Heterotrigona itama, by UHPLC-Q-TOF/MS and NMR

A reliable, rapid analytical method was established for the characterization of constituents of the ethanol extract of geopropolis (EEGP) produced by Malaysian stingless bees—Heterotrigona itama—by combining ultra-high-performance liquid chromatography with quadruple time-of-flight mass spectrometry (UHPLC-Q-TOF/MS). Based on known standards, the online METLIN database, and published literature, 28 compounds were confirmed. Phenolic acids, flavones, triterpenes and phytosterol were identified or tentatively identified using characteristic diagnostic fragment ions. The results indicated that terpenoids were the main components of EEGP, accompanied by low levels of phenolic acids, flavonoids, and phytosterol. Two major components were further purified by preparative high-performance liquid chromatography (PHPLC) and identified by nuclear magnetic resonance (NMR) as 24(E)-cycloart-24-ene-26-ol-3-one and 20-hydroxy-24-dammaren-3-one. These two triterpenes, confirmed in this geopropolis for the first time, are potential chemical markers for the identification of geopropolis from Malaysian stingless bees, H. itama.

Natural products isolated from Tetragonula carbonaria cerumen modulate free radical-scavenging and 5-lipoxygenase activities in vitro

Background

Propolis and cerumen are plant-derived products found in honeybees and stingless bees, respectively. Although propolis is an ancient folk medicine, the bioactivities of cerumen obtained from Australian native stingless bees (Tetragonula carbonaria) have not been widely studied. Therefore, we investigated selected anti-oxidant and anti-inflammatory properties of T. carbonaria cerumen.

Methods

A methanolic extract was prepared from the combined cerumen of 40 T. carbonaria hives, and HPLC was used to screen for chemical constituents that scavenged 2,2-azobis(2-methylpropionamidine) dihydrochloride (AAPH). The ability of cerumen extracts to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) and to interfere with leukotriene B₄ (LTB₄) production in ionomycin-stimulated human neutrophils was also examined.

Results

The extract dose-dependently scavenged DPPH (EC₅₀ = 27.0 ± 2.3 μg/mL); and inhibited the 5-lipoxygenase (5-LOX)-mediated oxidation of linoleic acid (IC₅₀ = 67.1 ± 9.6 μg/mL). Pre-treatment of isolated human neutrophils with the methanolic cerumen extract additionally inhibited the ionomycin-stimulated production of LTB₄ from these cells (IC₅₀ = 13.3 ± 5.3 μg/mL). Following multi-solvent extraction, the free radical-scavenging and 5-LOX-inhibiting activities of the initial cerumen extract were retained in a polar, methanol-water extract, which contained gallic acid and a range of flavonone and phenolic natural products.

Conclusions

The findings identify free radical scavenging activity, and interference by extracts of T. carbonaria cerumen in 5-LOX–LTB₄ signaling. Further investigation is needed to determine whether the extracts will provide therapeutic benefits for medical conditions in which oxidative stress and inflammation are implicated, including cardiovascular disease and impaired wound healing.

Cytotoxic Activity of Propolis Extracts from the Stingless Bee Trigona Sirindhornae Against Primary and Metastatic Head and Neck Cancer Cell Lines

Background:

Propolis, a resinous substance produced by the honeybee, has a wide spectrum of potent biological activities. However, anti-cancer activity of propolis obtained from Trigona sirindhornae, a new species of stingless bee, has not yet been reported. This study concerned cytotoxicity of propolis extracts from T. sirindhornae against two head and neck squamous cell carcinoma (HNSCC) cell lines.

Materials and Methods:

A dichloromethane extract of propolis (DMEP) was prepared generating 3 fractions: DMEP-A, DMEP-B, and DMEP-C. Genetically-matched HNSCC cell lines derived from primary (HN30) and metastatic sites (HN31) in the same patient were used to study cytotoxic effects of the DMEPs by MTT assays. The active compounds in the DMEPs were analyzed by reverse-phase high performance liquid chromatography.

Results:

DMEP-A exhibited cytotoxic activity on HN30 cells with significantly decreased viability at 200 µg/ml compared with the control (p<0.05). However, no significant cytotoxic effect was evident in HN31 cells. DMEP-B and DMEP-C significantly decreased the viability of both cell lines from 100–200 µg/ml and 50–200 µg/ml, respectively (p<0.05). Interestingly, HN31 cells were more toxically sensitive compared with the HN30 cells when treated with DMEP-B and DMEP-C. IC₅₀ values for DMEP-B with HN30 and HN31 cells were more than 200 µg/ml and 199.8±1.05 µg/ml, respectively. The IC₅₀ of DMEP-C to HN30 and HN31 cells was found to be 114.3±1.29 and 76.33±1.24 µg/ml, respectively. Notably, apigenin, pinocembrin, p-coumaric acid, and caffeic acid were not detected in our propolis extracts.

Conclusion:

T. sirindhornae produced propolis displays cytotoxic effects against HNSCC cells s. Moreover, DMEP-B and DMEP-C differentially inhibited the proliferation of a metastatic HNSCC cell line.

Stingless Bee Honey, the Natural Wound Healer: A Review

<b><i>Background:</i></b> The stingless bee is a natural type of bee that exists in almost every continent. The honey produced by this bee has been widely used across time and space. The distinctive feature of this honey is that it is stored naturally in the pot (cerumen), thus contributing to its beneficial properties, especially in the wound healing process. <b><i>Methods:</i></b> In this article, several studies on stingless bee honey that pointed out the numerous therapeutic profiles of this honey in terms of its antioxidant, antimicrobial, anti-inflammatory, as well as moisturizing properties are reviewed. All of these therapeutic properties are related to wound healing properties. <b><i>Results:</i></b> Antioxidant in stingless bee honey could break the chain of free radicals that cause a detrimental effect to the wounded area. Furthermore, the antimicrobial properties of stingless bee honey could overcome the bacterial contamination and thus improve the healing rate. Moreover, the anti-inflammatory attribute in this honey could protect the tissue from highly toxic inflammatory mediators. The moisturizing properties of the honey could improve wound healing by promoting angiogenesis and oxygen circulation. <b><i>Conclusion:</i></b> The application of honey to the wound has been widely used since ancient times. As a result, it is essential to understand the pharmacological mechanism of the honey towards the physiology of the wounded skin in order to optimize the healing rate in the future.

Chemical composition and antimicrobial activity of honeybee (Apis mellifera ligustica) propolis from subtropical eastern Australia

Propolis is a material manufactured by bees and contains beeswax, bee salivary secretions and plant resins. Propolis preparations have been used for millennia by humans in food, cosmetics and medicines due to its antibacterial effects. Within the hive, propolis plays an important role in bees' health, with much of its bioactivity largely dependent on the plant resins the bees select for its production. Few chemical studies are available on the chemistry of propolis produced by Australian honeybees (Apis mellifera, Apidae). This study aimed to determine the chemical composition as well as in vitro antimicrobial effects of propolis harvested from honeybees in subtropical eastern Australia. Honeybee propolis was produced using plastic frames and multiple beehives in two subtropical sites in eastern Australia. Methanolic extracts of propolis were analysed by liquid chromatography with ultraviolet detection and high-resolution mass spectrometry (ultra-high-pressure liquid chromatography (UHPLC)-UV-high-resolution tandem mass spectrometry (HR-MS/MS)) and by gas chromatography mass spectrometry (GC-MS). The resulting chemical data were dereplicated for compound characterisation. The two crude extracts in abs. ethanol were tested in vitro by the agar diffusion and broth dilution methods, using a phenol standard solution as the positive control and abs. ethanol as the negative control. Chemical constituents were identified to be pentacyclic triterpenoids and C-prenylated flavonoids, including Abyssinoflavanone VII, Propolin C and Nymphaeol C. The two propolis crude extracts showed bactericidal effects at the minimal inhibitory concentrations of 0.37-2.04 mg mL(-1) against Staphylococcus aureus ATCC 25923. However, the extracts were inactive against Klebsiella pneumoniae ATCC 13883 and Candida albicans ATCC 10231. The antistaphylococcal potential of propolis was discussed, also in relation to honeybees' health, as it warrants further investigations on the social and individual immunities of Australian honeybees.

Do Hybrid Trees Inherit Invasive Characteristics? Fruits of Corymbia torelliana X C. citriodora Hybrids and Potential for Seed Dispersal by Bees

Tree invasions have substantial impacts on biodiversity and ecosystem functioning, and trees that are dispersed by animals are more likely to become invasive. In addition, hybridisation between plants is well documented as a source of new weeds, as hybrids gain new characteristics that allow them to become invasive. Corymbia torelliana is an invasive tree with an unusual animal dispersal mechanism: seed dispersal by stingless bees, that hybridizes readily with other species. We examined hybrids between C. torelliana and C. citriodora subsp. citriodora to determine whether hybrids have inherited the seed dispersal characteristics of C. torelliana that allow bee dispersal. Some hybrid fruits displayed the characteristic hollowness, resin production and resin chemistry associated with seed dispersal by bees. However, we did not observe bees foraging on any hybrid fruits until they had been damaged. We conclude that C. torelliana and C. citriodora subsp. citriodora hybrids can inherit some fruit characters that are associated with dispersal by bees, but we did not find a hybrid with the complete set of characters that would enable bee dispersal. However, around 20,000 hybrids have been planted in Australia, and ongoing monitoring is necessary to identify any hybrids that may become invasive.

In vitro and in vivo characterization of the anticancer activity of Thai stingless bee (Tetragonula laeviceps) cerumen

Tetragonula laeviceps cerumen was sequentially extracted with 80% (v/v) methanol, dichloromethane, and hexane and also in the reverse order. By the MTT assay and the respective 50% inhibition concentration value, the most active fraction was further purified to apparent homogeneity by bioassay-guided silica gel column chromatography. α-Mangostin was identified by high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance analyses. It had a potent cytotoxicity against the BT474, Chago, Hep-G2, KATO-III, and SW620 cell lines (IC50 values of 1.22 ± 0.03, 2.25 ± 0.20, 0.94 ± 0.01, 0.88 ± 0.16, and 1.50 ± 0.39 µmol/L, respectively). The in vitro cytotoxicity of α-mangostin against the five human cancer cell lines and primary fibroblasts was further characterized by real-time impedance-based analysis. Interestingly, α-mangostin was more cytotoxic against the cancer-derived cell lines than against the primary fibroblasts. Later, the migration assay was performed by continuously measuring the attachment of cells to the plate electrodes at the bottom of the transwell membrane. The combined caspase-3 and -7 activities were assayed by the Caspase-Glo® 3/7 kit. It showed that the cytotoxic mechanism involved caspase-independent apoptosis, while at low (non-toxic) concentrations α-mangostin did not significantly alter cell migration. Furthermore, the in vivo cytotoxicity and angiogenesis were determined by alkaline phosphatase staining in zebrafish embryos along with monitoring changes in the transcript expression level of two genes involved in angiogenesis (vegfaa and vegfr2) by quantitative real-time reverse transcriptase- polymerase chain reaction. It was found that the in vivo cytotoxicity of α-mangostin against zebrafish embryos had a 50% lethal concentration of 9.4 µM, but no anti-angiogenic properties were observed in zebrafish embryos at 9 and 12 µM even though it downregulated the expression of vegfaa and vegfr2 transcripts. Thus, α-mangostin is a major active compound with a potential anticancer activity in T. laeviceps cerumen in Thailand.

Recent advances in the chemical composition of propolis

Propolis is a honeybee product with broad clinical applications. Current literature describes that propolis is collected from plant resins. From a systematic database search, 241 compounds were identified in propolis for the first time between 2000 and 2012; and they belong to such diverse chemical classes as flavonoids, phenylpropanoids, terpenenes, stilbenes, lignans, coumarins, and their prenylated derivatives, showing a pattern consistent with around 300 previously reported compounds. The chemical characteristics of propolis are linked to the diversity of geographical location, plant sources and bee species.

In vitro cytotoxicity of Indonesian stingless bee products against human cancer cell lines

OBJECTIVE

To screen crude extracts of propolis, bee pollen and honey from four stingless bee species [Trigona incisa (T. incisa)], Timia apicalis, Trigona fusco-balteata and Trigona fuscibasis) native to East Kalimantan, Indonesia for cytotoxic activity against five human cancer cell lines (HepG2, SW620, ChaGo-I, KATO-III and BT474).

METHODS

All samples were extracted with methanol, and then subpartitioned with n-hexane and ethyl acetate. Each crude extract was screened at 20 µg/mL for in vitro cytotoxicity against the cell lines using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In addition, four previously shown bioactive components from propolis (apigenin, caffeic acid phenyl ester, kaempferol and naringenin) and two chemotherapeutic drugs (doxorubicin and 5-fluorouracil) were used to evaluate the sensitivity of the cell lines.

RESULTS

Overall, crude extracts from propolis and honey had higher cytotoxic activities than bee pollen, but the activity was dependent upon the extraction solvent, bee species and cell line. Propolis extracts from T. incisa and Timia apicalis showed the highest and lowest cytotoxic activity, respectively. Only the HepG2 cell line was broadly sensitive to the honey extracts. For pure compounds, doxorubicin was the most cytotoxic, the four propolis compounds the least, but the ChaGo-I cell line was sensitive to kaempferol at 10 µg/mL and KATO-III was sensitive to kaempferol and apigenin at 10 µg/mL. All pure compounds were effective against the BT474 cell line.

CONCLUSIONS

Propolis from T. incisa and Trigona fusco-balteata contain an in vitro cytotoxic activity against human cancer cell lines. Further study is required, including the isolation and characterization of the active antiproliferative agent(s).

Anti-staphylococcal activity of C-methyl flavanones from propolis of Australian stingless bees (Tetragonula carbonaria) and fruit resins of Corymbia torelliana (Myrtaceae)

Propolis of Australian stingless bees (Tetragonula carbonaria, Meliponini) originating from Corymbia torelliana (Myrtaceae) fruit resins was tested for its antimicrobial activities as well as its flavonoid contents. This study aimed at the isolation, structural elucidation and antibacterial testing of flavanones of C. torelliana fruit resins that are incorporated into stingless bee propolis. Flavanones of this study were elucidated by spectroscopic and spectrometric methods including UV, 1D and 2D NMR, EI-MS, ESI-MS and HR-MS. The results indicated known C-methylated flavanones namely, 1 (2S)-cryptostrobin, its regioisomer 2 (2S)- stroboponin, 3 (2S)- cryptostrobin 7-methyl ether, and 6 (2S)- desmethoxymatteucinol, and known flavanones 4 (2S)- pinostrobin and 5 (2S)- pinocembrin as markers for C. torelliana fruit resins and one propolis type. Ethanolic preparations of propolis were shown to be active against Staphylococcus aureus (ATCC 25923) and to a lesser extent against Pseudomonas aeruginosa (ATCC 27853). C. torelliana flavanones inhibited the growth of S. aureus therefore contributing to the antibacterial effects observed for Australian stingless bee propolis extracts.

Structure and antioxidant activity of polyphenols derived from propolis

Propolis is a potential source of natural antioxidants such as phenolic acids and flavonoids. Its wide biological effects have been known and used since antiquity. In the modern world natural substances are sought which would be able to counteract the effects of antioxidative stress, which underlies many diseases, such as cancer, diabetes and atherosclerosis. This paper aims to present the antioxidative activity of phenolic acids and flavonoids present in Polish propolis and the relationship between their chemical structure and antioxidative activity influencing its medicinal properties. Data concerning the biological activity of propolis are summarized here, including its antibacterial, anti-inflammatory, anticarcinogenic, antiatherogenic, estrogenic effects, as well as AIDS- counteracting and reparative-regenerative function.

Effect of Australian propolis from stingless bees (Tetragonula carbonaria) on pre-contracted human and porcine isolated arteries

Bee propolis is a mixture of plant resins and bee secretions. While bioactivity of honeybee propolis has been reported previously, information is limited on propolis from Australian stingless bees (Tetragonula carbonaria). The aim of this study was to investigate possible vasomodulatory effects of propolis in KCl-precontracted porcine coronary arteries using an ex vivo tissue bath assay. Polar extracts of propolis produced a dose-dependent relaxant response (EC₅₀=44.7±7.0 μg/ml), which was unaffected by endothelial denudation, suggesting a direct effect on smooth muscle. Propolis markedly attenuated a contractile response to Ca²⁺ in vessels that were depolarised with 60 mM KCl, in Ca²⁺-free Krebs solution. Propolis (160 µg/ml) reduced vascular tone in KCl pre-contracted vessels to near-baseline levels over 90 min, and this effect was partially reversible with 6h washout. Some loss in membrane integrity, but no loss in mitochondrial function was detected after 90 min exposure of human cultured umbilical vein endothelial cells to 160 µg/ml propolis. We conclude that Australian stingless bee (T. carbonaria) propolis relaxes porcine coronary artery in an endothelial-independent manner that involves inhibition of voltage-gated Ca²⁺ channels. This effect is partially and slowly reversible upon washout. Further studies are required to determine the therapeutic potential of Australian stingless bee propolis for conditions in which vascular supply is compromised.

In vitro antiproliferative/cytotoxic activity on cancer cell lines of a cardanol and a cardol enriched from Thai Apis mellifera propolis

Background

Propolis is a complex resinous honeybee product. It is reported to display diverse bioactivities, such as antimicrobial, anti-inflammatory and anti-tumor properties, which are mainly due to phenolic compounds, and especially flavonoids. The diversity of bioactive compounds depends on the geography and climate, since these factors affect the floral diversity. Here, Apis mellifera propolis from Nan province, Thailand, was evaluated for potential anti-cancer activity.

Methods

Propolis was sequentially extracted with methanol, dichloromethane and hexane and the cytotoxic activity of each crude extract was assayed for antiproliferative/cytotoxic activity in vitro against five human cell lines derived from duet carcinoma (BT474), undifferentiated lung (Chaco), liver hepatoblastoma (Hep-G₂), gastric carcinoma (KATO-III) and colon adenocarcinoma (SW620) cancers. The human foreskin fibroblast cell line (Hs27) was used as a non-transformed control. Those crude extracts that displayed antiproliferative/cytotoxic activity were then further fractionated by column chromatography using TLC-pattern and MTT-cytotoxicity bioassay guided selection of the fractions. The chemical structure of each enriched bioactive compound was analyzed by nuclear magnetic resonance and mass spectroscopy.

Results

The crude hexane and dichloromethane extracts of propolis displayed antiproliferative/cytotoxic activities with IC₅₀ values across the five cancer cell lines ranging from 41.3 to 52.4 μg/ml and from 43.8 to 53.5 μg/ml, respectively. Two main bioactive components were isolated, one cardanol and one cardol, with broadly similar in vitro antiproliferation/cytotoxicity IC₅₀ values across the five cancer cell lines and the control Hs27 cell line, ranging from 10.8 to 29.3 μg/ml for the cardanol and < 3.13 to 5.97 μg/ml (6.82 - 13.0 μM) for the cardol. Moreover, both compounds induced cytotoxicity and cell death without DNA fragmentation in the cancer cells, but only an antiproliferation response in the control Hs27 cells However, these two compounds did not account for the net antiproliferation/cytotoxic activity of the crude extracts suggesting the existence of other potent compounds or synergistic interactions in the propolis extracts_.

Conclusion

This is the first report that Thai A. mellifera propolis contains at least two potentially new compounds (a cardanol and a cardol) with potential anti-cancer bioactivity. Both could be alternative antiproliferative agents for future development as anti-cancer drugs.