Plant Sources Responsible for the Chemical Composition and Main Bioactive Properties of Poplar-Type Propolis

Effects of propolis intake on endurance exercise and molecular signaling related to inflammation and oxidative stress

Honey bees extract sticky material from the exudates of different plants which transform afterwards to propolis. Propolis from several global locations has been shown to contain a wide variety of polyphenolic chemicals. Recent studies have revealed that propolis possesses antioxidant, anti-inflammatory, and immunomodulatory abilities. In laboratory animal studies, it has been demonstrated that propolis can enhance the functioning of the antioxidant defense system and decrease the activity of nuclear factor-kappa B. As a result, they can effectively alleviate the damage caused by exercise. One of the main flavonoids found in propolis, quercetin, has been demonstrated to enhance muscle mitochondrial biogenesis and exercise capacity. Propolis may aid athletes in preventing oxidative and inflammatory damage to their muscles during exercise and enhance their athletic performance. The goal of the current review was to evaluate how propolis consumption affected the molecular signaling associated with antioxidant/oxidant state, pro/anti-inflammatory cytokines, and anaerobic/aerobic endurance.

Polyphenolic Composition, Antioxidant Activity, and Cytotoxic Effect of Male Floral Buds from Three Populus Species Growing in the South of Romania

Three poplar species widely distributed in southern Romania were investigated for their chemical composition and bioactivity. Male buds from black poplar (Populus nigra L.), white poplar (Populus alba L.), and Euroamerican hybrid poplar (Populus × euramericana (Dode) Guinier.) were analyzed using HPTLC, HPLC, GC-MS, and spectrophotometric assays. The analysis revealed predominantly polyphenolic compounds, including phenolic acids and flavonoids, secondary metabolites recognized for their antioxidant properties, particularly valuable in alleviating oxidative stress disorders. Heavy metal content was measured using atomic absorption spectroscopy, and antioxidant capacity was assessed through DPPH and FRAP assays alongside a cytotoxicity evaluation. Polyphenolic content ranged from 19.26 to 33.37 mg GAE/g DW and flavonoid content from 2.15 to 4.45 mg RE/g DW. All three species demonstrated notable antioxidant capacity and cytotoxic activity. Hydroethanolic extracts of P. nigra and P. euramericana showed higher antioxidant activity than aqueous extracts, with P. nigra achieving the lowest IC50 value overall, highlighting the influence of solvent choice on antioxidant efficacy. Furthermore, poplar hydroethanolic extracts exhibited concentration-dependent cytotoxicity against fibroblast-like human osteosarcoma MG63 cell lines, with IC50 values of 42.55 µg/mL for P. nigra, 40.87 µg/mL for P. × euramericana, and 132.49 µg/mL for P. alba, underscoring significant interspecies variability in cytotoxic potency. These findings suggest that male floral buds from Romanian poplar species may serve as valuable sources of bioactive compounds with therapeutic potential.

Inhibitory Effects and Composition Analysis of Romanian Propolis: Applications in Organic and Sustainable Agriculture

Propolis is a sustainable and environmentally friendly agrochemical of natural origin, a resinous mixture produced by honeybees. It is used as a natural remedy in multiple pathologies., but it is also a natural defense enhancer, a phytostimulator that helps to bind, bloom, and pollinate plants. Propolis is used in organic farming as a phytoprotector and phytostimulator. The present study investigates the main physical-chemical parameters of Romanian propolis, its antifungal activity against five fungal strains (Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum, Fusarium oxysporum, and Rhizopus stolonifer) and its phyto-inhibitory activity when it is applied on the layer and under the layer for different grain crops (wheat, maize, oats, and barley). Different doses were used-1, 5, and 10 g of propolis powder-and the growth of the plume was monitored for 13 days. The physical-chemical parameters investigated are volatile oils, wax, oxidation index, melting point, dry matter, ash, and resin, and maximum values were obtained for phenols (189.4 mgGAE/g), flavonoids (84.31 mgQE/g), and IC50 (0.086 µg/mL). Propolis demonstrates high antifungal activity against all fungal strains. The results showed that propolis has the best phyto-inhibition potential among the studied grain crops when it is applied on the layer, with the lowest plume growth for maize (14 mm), followed by oats, barley, and lastly wheat (24 mm). Propolis can find increasing application in sustainable and environmentally friendly agriculture and the obtaining of organic food.

Engineering an Escherichia coli strain for enhanced production of flavonoids derived from pinocembrin

BACKGROUND

Flavonoids are a structurally diverse group of secondary metabolites, predominantly produced by plants, which include a range of compounds with pharmacological importance. Pinocembrin is a key branch point intermediate in the biosynthesis of a wide range of flavonoid subclasses. However, replicating the biosynthesis of these structurally diverse molecules in heterologous microbial cell factories has encountered challenges, in particular the modest pinocembrin titres achieved to date. In this study, we combined genome engineering and enzyme candidate screening to significantly enhance the production of pinocembrin and its derivatives, including chrysin, pinostrobin, pinobanksin, and galangin, in Escherichia coli.

RESULTS

By implementing a combination of established strain engineering strategies aimed at enhancing the supply of the building blocks phenylalanine and malonyl-CoA, we constructed an E. coli chassis capable of accumulating 353 ± 19 mg/L pinocembrin from glycerol, without the need for precursor supplementation or the fatty acid biosynthesis inhibitor cerulenin. This chassis was subsequently employed for the production of chrysin, pinostrobin, pinobanksin, and galangin. Through an enzyme candidate screening process involving eight type-1 and five type-2 flavone synthases (FNS), we identified Petroselinum crispum FNSI as the top candidate, producing 82 ± 5 mg/L chrysin. Similarly, from a panel of five flavonoid 7-O-methyltransferases (7-OMT), we found pinocembrin 7-OMT from Eucalyptus nitida to yield 153 ± 10 mg/L pinostrobin. To produce pinobanksin, we screened seven enzyme candidates exhibiting flavanone 3-hydroxylase (F3H) or F3H/flavonol synthase (FLS) activity, with the bifunctional F3H/FLS enzyme from Glycine max being the top performer, achieving a pinobanksin titre of 12.6 ± 1.8 mg/L. Lastly, by utilising a combinatorial library of plasmids encoding G. max F3H and Citrus unshiu FLS, we obtained a maximum galangin titre of 18.2 ± 5.3 mg/L.

CONCLUSION

Through the integration of microbial chassis engineering and screening of enzyme candidates, we considerably increased the production levels of microbially synthesised pinocembrin, chrysin, pinostrobin, pinobanksin, and galangin. With the introduction of additional chassis modifications geared towards improving cofactor supply and regeneration, as well as alleviating potential toxic effects of intermediates and end products, we anticipate further enhancements in the yields of these pinocembrin derivatives, potentially enabling greater diversification in microbial hosts.

Phytochemical Characterization and Assessment of the Wound Healing Properties of Three Eurasian Propolis

OBJECTIVES

The objective of this study is to evaluate the wound healing potential of Eurasian propolis by analyzing the phytochemical profile and the biological effects of three representative propolis samples.

METHODS

Specific colorimetric assays were used to estimate the total phenolic and flavonoid contents and the triterpenoids content. Some of the main components of Eurasian propolis (pinocembrin, pinobanksin, CAPE, chrysin and galangin) were analyzed using HPLC-DAD. Scavenging activity and total antioxidant capacity were assessed through DPPH and ORAC assays, respectively. Human keratinocyte, fibroblast, and monocytic cell lines were used for the biological in vitro analyses. The direct wound healing properties were tested through scratching assays and ELISA kits for the assessment of the production of growth factors (FGF-7, Latency Associated Peptide-LAP), while the indirect effects were evaluated through the estimation of the levels of MMP9, IL-1β, IL-8, and TNF-α using ELISA kits together with a cell-free test on the inhibition capacity on collagenases. Network Pharmacology analysis was employed to further explore possible mechanisms of the action of propolis on the healing process.

RESULTS

The analyses confirmed the high phenolic content of Eurasian propolis (142.50-211.30 mg GAE/g), dominated by flavonoids (95.50-196.80 mg Galangin Equivalents/g), and terpenes (431.50-650.00 mg β-sitosterol Equivalents/g), while also verifying the significant antioxidant (4.9-8.9 mM/g Trolox Equivalents) and antiradical (DPPH IC50 26.1-54.4 μg/mL) activities. The samples showed indirect wound healing properties by mitigating inflammation and remodeling (reduced IL-1β and MMP9) and potentially modulating the immune response (upregulated IL-8). In vitro studies confirmed these effects, demonstrating decreased MMP9 production and collagenase inhibition when cells were co-treated with propolis and a stressor. Propolis also suppressed IL-1β release in fibroblasts, although its impact on TNF-α was inconclusive. Notably, co-treatment upregulated IL-8 in monocytes, suggesting a potential immunomodulatory role.

CONCLUSIONS

Eurasian propolis may not directly stimulate cell proliferation during wound healing. Its anti-inflammatory and immunomodulatory properties could indicate an indirect contribution in helping the process.

Hydrogel Containing Propolis: Physical Characterization and Evaluation of Biological Activities for Potential Use in the Treatment of Skin Lesions

BACKGROUND

Skin injury affects the integrity of the skin structure and induces the wound healing process, which is defined by a well-coordinated series of cellular and molecular reactions that aim to recover or replace the injured tissue. Hydrogels are a group of promising biomaterials that are able to incorporate active ingredients for use as dressings. This study aimed to synthesize hydrogels with and without propolis extract and evaluate their physical characteristics and biological activities in vitro for potential use as active dressings in the treatment of skin lesions.

METHODS

The antifungal [Candida albicans (C. albicans) and Candida tropicalis (C. tropicalis)] and antibacterial [Staphylococcus aureus (S. aureus), Pseudomonas aeruginosas (P. aeruginosas) and Escherichia coli (E. coli)] activity was assessed by the microdilution method in plates and antioxidant potential by the reduction of the phosphomolybdate complex.

RESULTS

The hydrogels showed good water absorption capacity, high solubility, and high gel fraction, as well as good porosity, water retention, and vapor transmission rates. They revealed a totally amorphous structure. The extract and the hydrogels containing the propolis extract (1.0% and 2.5%) did not inhibit fungal growth. However, they showed antibacterial activity against strains of S. aureus and P. aeruginosas. Regarding the E. coli strain, only the extract inhibited its growth. It showed good antioxidant activity by the evaluation method used.

CONCLUSIONS

Therefore, the hydrogels containing propolis extract can be a promising alternative with antibacterial and antioxidant action for use as dressings for the treatment of skin lesions.

Chemical profiling, bioactive compounds, antioxidant, and anti-inflammatory activities of Indonesian propolis extract produced by Tetragonula laeviceps

Propolis produced by stingless bees contains various chemical compounds that contribute to its bioactivity. The availability of certain plants at the growth site and the propolis's geographic origin have a significant impact on its chemical composition. The objective of this study was to examine the chemical profile, yield, total flavonoid and phenolic content, and in vitro antioxidant and anti-inflammatory effects of propolis extract from 10 distinct locations in Indonesia. The yield of propolis extract investigated in this study lies in the range of 26.25 ± 1.76 to 43.25 ± 3.60 %. The total phenolic content of the propolis extract varies from 50.03 ± 3.40-98.03 ± 13.94 mg GAE/g whereas the total flavonoid content of the propolis extract varies from and 0.70 ± 0.08-57.76 ± 0.67 mg QE/g. The antioxidant activity of the propolis extract in terms of IC50 values lies in the range of 332.07 ± 6.12 to 831.48 ± 29.48 ppm whereas the anti-inflammatory activity of the propolis extract in terms of IC50 values lies in the range of 28.69 ± 4.95 to 44.12 ± 19.22 ppm. Both the total flavonoid and phenolic content of the propolis extract from various locations were correlated with the antioxidant activities and anti-inflammatory activities. The results indicate that there was a significant negative correlation between the total flavonoid and phenolic content of the propolis extract with the antioxidant activity. However, the anti-inflammatory activity was not strongly correlated with the total flavonoid and phenolic content of the propolis extract. There were 36 volatile compounds in the propolis extract as identified by the Gas Chromatography-Mass Spectrometry with triterpenoid as the major substances (28.66-44.86 %). The presence of anti-inflammatory compounds particularly α, β-Amyrin (2.2-6.52 %) and lupeol (2-4.72 %) in the propolis extract highlights the potential of propolis in health and medicine application.

The Comparative Study of the Antioxidant and Antibacterial Effects of Propolis Extracts in Veterinary Medicine

Antimicrobial resistance (AMR) is one of the biggest threats to human and animal health. Efforts to combat AMR include the introduction of antimicrobial drugs as alternative treatment options. To contribute to an effective plan for the treatment of infectious diseases caused by bacteria, the development of new antimicrobial agents is increasingly being explored. Propolis has garnered significant attention from both scientists and industry due to its extensive spectrum of biological activity. The growing interest in polyphenols of natural origin and their plant sources further encourages the investigation of their chemical composition and biological effects. Propolis serves as a rich source of phenolic compounds. Baltic region propolis, classified as poplar-type propolis, was selected for this study, and extracts were prepared using raw propolis materials from various Baltic countries. The production of liquid extracts utilized a combination of 70 percent ethanol, a mixture of water and poloxamer P407, and DES (deep eutectic solvent). The research aims to produce liquid propolis extracts using different solvents and to assess their chemical composition, antioxidant, and antimicrobial activity against different veterinary pathogens. Antioxidant activity was evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl), revealing antioxidant activity in all extracts, with results correlating with the total phenolic compound content. It was found that p-coumaric acid predominated in the studied propolis extracts (in ethanol extracts 1155.90-1506.65 mg/g, in DES extracts 321.13-954.76 mg/g, and in polymeric extracts 5.34-30.80 mg/g), with smaller amounts of ferulic acid and vanillin detected. Clinical and reference bacterial strains were collected from the Lithuanian University of Health Sciences, the Academy of Veterinary Medicine, and the Institute of Microbiology and Virology. To effectively treat bacterial infections, the antimicrobial activity of propolis extracts was tested against six pathogenic bacterial species and one pathogenic fungus (S. aureus, S. agalactiae, B. cereus, E. faecalis, E. coli, P. aeruginosa, and C. albicans). Antimicrobial activity studies demonstrated that DES propolis extracts exhibited stronger antimicrobial activity compared to ethanolic propolis extracts. The minimum inhibitory concentration (MIC) values of DES propolis extracts against the tested strains ranged between 50 and 1000 μg/mL. Considering the study results, it can be concluded that propolis from the Baltic region is abundant in phenolic compounds exhibiting antioxidant and antibacterial activities.

Exudate and Propolis from Escallonia pulverulenta: Phytochemical Characterization and Antibacterial Activity

Propolis is a complex mixture formed from exudates that bees collect from plants and then mix with beeswax and their own salivary enzymes. Chilean propolis is characterized by the presence of phenolic compounds, which are considered responsible for the biological activities. The endemic species Escallonia pulverulenta (Ruiz and Pav.) Pers. [Escalloniaceae] is a recognized source of exudate to produce propolis. This study reports for the first time the chemical profile and antibacterial activity of E. pulverulenta exudate and leaves, as well as two samples of Chilean propolis. Palynological and morphological analysis showed the presence of E. pulverulenta as one of the main species in the propolis samples. UPLC-MS/MS analyses enabled the identification of phenolic acids in the leaves and in the propolis. Conversely, flavonoids are mainly present in exudates and propolis. Quercetin is the most abundant flavonol in the exudate, with similar concentrations in the propolis samples. Nevertheless, the main compound present in both samples of propolis was the flavanone pinocembrin. The antibacterial results obtained for exudate and propolis have shown a similar behavior, especially in the inhibition of Streptococcus pyogenes. These results show the importance of the exudates collected by the bees in the chemical composition and antibacterial capacity of propolis.

Poplar Bud (Populus) Extraction and Chinese Propolis Counteract Oxidative Stress in Caenorhabditis elegans via Insulin/IGF-1 Signaling Pathway

Poplar buds are characterized by a high content of phenolic compounds, which exhibit a broad spectrum of biological activities. However, the relationship between Chinese propolis and poplar buds based on their antioxidant capacities and underlying mechanisms remains unclear. This study aimed to investigate the antioxidant properties of poplar bud (Populus) extract (PBE) and Chinese propolis (CP) and to elucidate the mechanisms behind their activity. High-performance liquid chromatography (HPLC) analysis revealed that both PBE and CP contain a significant amount of phenolic acids and flavonoids. 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric-reducing antioxidant power (FRAP) assays demonstrated that PBE and CP possess excellent antioxidant activity. Furthermore, administration of PBE and CP improved the survival rate of C. elegans under oxidative stress. They also decreased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), while enhancing the activity of antioxidant enzymes (SOD, CAT). PBE and CP intervention upregulated the expression of key genes daf-16, sod-3, hsp-16.2, and skn-1 in nematodes. This suggests that the antioxidant activity of PBE and CP is dependent on daf-16 and skn-1 signaling pathways. In conclusion, poplar bud extracts ha have the potential to become a substitute for propolis and a potential therapeutic agent for treating diseases associated with oxidative damage.

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.

Advances in the phytochemical screening and biological potential of propolis

Propolis is a natural resinous product collected from different parts of plants by bees and mixed with their salivary secretions. The occurrence of more than 180 different chemotypes has flavonoids, phenolic acids, esters, and phenolic aldehydes, as well as balsamic resins, beeswax, pollen, and essential and aromatic oils, among others. Its biological potential documented throughout the world justifies the need, from time to time, to organize reviews on the subject, with the intention of gathering and informing about the update on propolis. In this review (CRD42020212971), phytochemical advances, in vitro, in vivo, and clinical biological assays of pharmacological interest are showcased. The focus of this work is to present propolis clinical safety assays, antitumor, analgesic, antioxidant, anti-inflammatory, and antimicrobial activities. This literature review highlights propolis' promising biological activity, as it also suggests that studies associating propolis with nanotechnology should be further explored for enhanced bioprocessing applications.

Chemical Characterization, Bioactivity and Toxicity of European Flora Plant Extracts in Search for Potential Natural Origin Preservatives

Consumer demand for natural and healthier products has led to an increasing interest in the bioactive and therapeutic properties of plant extracts. In this study, we evaluated the phenolic compounds profile, bioactivities, and toxicities of plant extracts from eight European flora species, including Calendula officinalis L., Calluna vulgaris (L.) Hull, Hippophae rhamnoides L., Juglans regia L., Mentha cervina L., Rubus idaeus L., Sambucus nigra L., and Vitis vinifera L. The aim was to identify potential preservatives of natural origin. Phenolic compounds were identified by HPLC-DAD-ESI-MS. Caffeic acid derivatives, ellagitannins, flavonols, and flavones were the major phenolic compounds identified. The total phenolic content varied from 16.0 ± 0.2 (V. vinifera) to 123 ± 2 mg/g (H. rhamnoides) of dry extract. All extracts showed antioxidant potential and exhibited activity against some of the microorganisms tested. S. nigra showed the highest activity in the inhibition of oxidative hemolysis (OxHLIA) assay and H. rhamnoides, notably, had the lowest IC50 values in TBARS and DPPH assays, as well as the lowest minimum inhibitory concentration (MIC) values. Regarding in vitro cytotoxicity, in tumor and non-tumor cell lines, although some extracts revealed toxicity against normal cells, it was found that the samples C. vulgaris, V. vinifera and R. idaeus might be used against tumor cells since the active concentration is much lower than the one causing toxicity. In vivo acute toxicity tests using Artemia franciscana suggest low toxicity for most extracts, with LC50 > 400 mg/L. These results showed the potential of the studied extracts as natural preservatives, given their richness in compounds with bioactive properties, highlight their potential value to the production chain.

Exploring the Potential of Bee-Derived Antioxidants for Maintaining Oral Hygiene and Dental Health: A Comprehensive Review

Honey bee products comprise various compounds, including honey, propolis, royal jelly, bee pollen, bee wax and bee venom, which have long been recognized for their pharmacological and health-promoting benefits. Scientists have discovered that periodontal disorders stem from dental biofilm, an inflammatory response to bacterial overgrowth produced by dysbiosis in the oral microbiome. The bee products have been investigated for their role in prevention of oral diseases, which are attributed to a myriad of biologically active compounds including flavonoids (pinocembrin, catechin, caffeic acid phenethyl ester (CAPE) and galangin), phenolic acids (hydroxybenzoic acid, hydroxycinnamic acid, p-coumaric, ellagic, caffeic and ferulic acids) and terpenoids. This review aims to update the current understanding of role of selected bee products, namely, honey, propolis and royal jelly, in preventing oral diseases as well as their potential biological activities and mechanism of action in relation to oral health have been discussed. Furthermore, the safety of incorporation of bee products is also critically discussed. To summarize, bee products could potentially serve as a therapy option for people suffering from a variety of oral disorders.

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.

Biological Activity and Chemical Composition of Propolis from Various Regions of Poland

Propolis is one of the bee products, with multiple biological properties used in numerous applications. The research objective was to determine the chemical composition and biological properties (antibacterial, antifungal, antiviral, antioxidant, and cytoprotective activity) of propolis extracts collected from various regions of Poland. The results indicated that the total content of phenols (116.16-219.41 mg GAE/g EEP) and flavonoids (29.63-106.07 mg QE/g EEP) in propolis extracts depended on their geographic origin. The high content of epicatechin, catechin, pinobanksin, myricetin, and acids: vanillic and syringic in propolis samples was confirmed by chromatographic analysis. Moreover, the presence of caffeic acid phenethyl ester was confirmed in all samples. The origin of propolis also influenced the biological properties of its extracts. The propolis extracts were characterized by moderate DPPH free radical scavenging activity (29.22-35.14%), and relatively low ferrous iron chelating activity (9.33-32.32%). The results indicated also that the propolis extracts showed high activity in the protection of human red blood cells against free radicals generated from 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). The extracts exhibited diversified activity against the tested pathogenic bacteria and limited activity against fungal strains. The research of selected propolis extracts showed that only 2 of 5 examined samples showed moderate activity against HPV (human papillomaviruses) and the activity depended on its geographical distribution.

Developing Strategies to Help Bee Colony Resilience in Changing Environments

Climate change, loss of plant biodiversity, burdens caused by new pathogens, predators, and toxins due to human disturbance and activity are significant causes of the loss of bee colonies and wild bees. The aim of this review is to highlight some possible strategies that could help develop bee resilience in facing their changing environments. Scientists underline the importance of the links between nutrition, microbiota, and immune and neuroendocrine stress resistance of bees. Nutrition with special care for plant-derived molecules may play a major role in bee colony health. Studies have highlighted the importance of pollen, essential oils, plant resins, and leaves or fungi as sources of fundamental nutrients for the development and longevity of a honeybee colony. The microbiota is also considered as a key factor in bee physiology and a cornerstone between nutrition, metabolism, growth, health, and pathogen resistance. Another stressor is the varroa mite parasite. This parasite is a major concern for beekeepers and needs specific strategies to reduce its severe impact on honeybees. Here we discuss how helping bees to thrive, especially through changing environments, is of great concern for beekeepers and scientists.

Chemical Profile and Antioxidant Capacity of Propolis from Tetragonula, Lepidotrigona, Lisotrigona and Homotrigona Stingless Bee Species in Vietnam

The present study aimed to analyze and compare the chemical profile and antioxidant capacity of propolis from different bee species and different regions. The chemical profiles of propolis from six stingless bee species (Tetragonula iridipennis, T. laeviceps, Lepidotrigona terminata, L. ventralis, Lisotrigona carpenteri and Homotrigona apicalis) collected from a total of eight locations in Vietnam were investigated by gas chromatography-mass spectrometry (GC-MS). More than 70 compounds were identified, amongst which phenolic lipids (cardanols, resorcinols and anacardic acids), aromatic acids, triterpenes and xanthones. Taxonomic markers for Mangifera indica (phenolic lipids and cycloartane triterpenes) were detected in propolis from bees of the genera Tetragonula and Lepidotrigona, although in different amounts, whereas propolis from H. apicalis was characterized by triterpenes of the amyrine type, typical of dipterocarp trees. A clear discrimination between both groups was observed by principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). Propolis from Tetragonula and Lepidotrigona spp. and from Lisotrigona carpenteri, which is rich in xanthones, possesses higher radical scavenging and ferric-reducing capacity than that from H. apicalis. Propolis produced by all six stingless bee species in Vietnam was analyzed for the first time. In addition, this is the first report on L. carpenteri propolis.

Balsam Poplar Buds: Extraction of Potential Phenolic Compounds with Polyethylene Glycol Aqueous Solution, Thermal Sterilization of Extracts and Challenges to Their Application in Topical Ocular Formulations

Phenolic compounds of natural origin have been valued for their beneficial effects on health since ancient times. During our study, we performed the extraction of phenolic compounds from balsam poplar buds using different concentrations of aqueous polyethylene glycol 400 solvents (10-30% PEG400). The aqueous 30% PEG400 extract showed the best phenolic yield. The stability of the extract during autoclave sterilization was evaluated. The extract remained stable under heat sterilization. Ophthalmic formulations are formed using different concentrations (8-15%) of poloxamer 407 (P407) together with hydroxypropyl methylcellulose (0.3%), sodium carboxymethyl cellulose (0.3%) or hyaluronic acid (0.1%). Physicochemical parameters of the formulations remained significantly unchanged after sterilization. Formulations based on 12% P407 exhibited properties characteristic of in situ gels, the gelation point of the formulations was close to the temperature of the cornea. After evaluating the amount of released compounds, it was found that, as the concentration of polymers increases, the amount of released compounds decreases. Formulations based on 15% P407 released the least biologically active compounds. Sterilized formulations remained stable for 30 days.

Plants: Sources of Diversity in Propolis Properties

Propolis or “bee glue” is a resinous waxy substance that is produced by honeybees (Apis mellifera) by mixing the exudates collected from plants, namely tree buds, sap flows, leaves, branches and barks with their saliva and beeswax. Propolis composition is very complex. Its main constituents are resins and volatiles originating from plants and wax added by the bee. The biological activity of propolis is assigned to these plant-derived substances. The main three types of propolis are European propolis, called poplar type propolis; Green Brazilian propolis (derived mainly from the leaf resin of Baccharis dracunculifolia) and Red Cuban propolis (from the floral resin of Clusia rosea). The plant’s source gives it a specific composition and properties for the propolis types that are coming from different regions of the world. For this reason, studies on the chemical composition of propolis as well as its botanical sources resulting in its geographically conditioned diversity, were a very good theme for the present Special Issue (SI) of Plants journal. The present SI contains nine original contributions addressing propolis plant sources, their chemical composition and different bioactive properties derived from this origin. The chemical composition of propolis that is made by the bees was also discussed, as well as the different medical activities of propolis extract. The papers cover a wide range of subjects, including (i) the plant species used by the bees as raw material for propolis production, (ii) the biological activities of plant extracts related to propolis, (iii) the chemical composition of different types of propolis, (iv) the biological activity of propolis, (v) propolis and human health, and (vi) synergism between plants and propolis in human health. The studies have been carried out in both in vitro and in vivo surveys and a wide range of geographic regions are covered in the sample collection.

Calluna vulgaris as a Valuable Source of Bioactive Compounds: Exploring Its Phytochemical Profile, Biological Activities and Apitherapeutic Potential

Calluna vulgaris, belonging to the Ericaceae family, is an invasive plant that has widely spread from Europe all across Asia, North America, Australia and New Zealand. Being able to survive in rigid soil and environmental conditions, it is nowadays considered to be of high nature-conservation value. Known for its nutritional and medicinal properties, C. vulgaris stands out for its varied physiochemical composition, spotlighting a wide range of biological activity. Among the most important bioactive compounds identified in C. vulgaris, the phenolic components found in different parts of this herbaceous plant are the main source of its diverse pro-health properties (antioxidant, anti-inflammatory, antimicrobial, chemoprotective, etc.). Nonetheless, this plant exhibits an excellent nectariferous potential for social insects such as honeybees; therefore, comparing the bioactive compounds observed in the plant and in the final product of the beehive, namely honey, will help us understand and find new insights into the health benefits provided by the consumption of C. vulgaris-related products. Thus, the main interest of this work is to review the nutritional profile, chemical composition and biological activities of the C. vulgaris plant and its related honey in order to encourage the future exploration and use of this health-promoting plant in novel foods, pharmacological products and apitherapy.

Selective Cytotoxicity of Portuguese Propolis Ethyl Acetate Fraction towards Renal Cancer Cells

Renal cell carcinoma is the most lethal cancer of the urological system due to late diagnosis and treatment resistance. Propolis, a beehive product, is a valuable natural source of compounds with bioactivities and may be a beneficial addition to current anticancer treatments. A Portuguese propolis sample, its fractions (n-hexane, ethyl acetate, n-butanol and water) and three subfractions (P1–P3), were tested for their toxicity on A498, 786-O and Caki-2 renal cell carcinoma cell lines and the non-neoplastic HK2 kidney cells. The ethyl acetate fraction showed the strongest toxicity against A498 (IC₅₀ = 0.162 µg mL⁻¹) and 786-O (IC₅₀ = 0.271 µg mL⁻¹) cells. With similar toxicity against 786-O, P1 (IC₅₀ = 3.8 µg mL⁻¹) and P3 (IC₅₀ = 3.1 µg mL⁻¹) exhibited greater effect when combined (IC₅₀ = 2.5 µg mL⁻¹). Results support the potential of propolis and its constituents as promising coadjuvants in renal cell carcinoma treatment.

Antibacterial Activity of Romanian Propolis against Staphylococcus aureus Isolated from Dogs with Superficial Pyoderma: In Vitro Test

Staphylococcal infection treatment in dogs is frequently associated with adverse side effects, high costs, prolonged treatment, and resistant strain selection. Staphylococcus aureus is the most frequently isolated staphylococci in cases of canine superficial pyoderma. The number of Staphylococcus strains to exhibit primary resistance to various drugs in vitro is increasing. Propolis has a diverse chemical composition and well-known therapeutic properties against bacterial infections. The current investigation evaluated in vitro the antimicrobial activity of the commercial allopathic antimicrobials, Romanian propolis ethanolic extracts, against clinical Staphylococcus aureus strains isolated from superficial dermatitis clinical samples in dogs and two reference strains: Staphylococcus aureus ATCC 25923 and Staphylococcus aureus ATCC 43300, as the MSSA and MRSA positive controls, respectively, in western Romania. We used the microdilution broth technique to evaluate the susceptibility profile of the bacteria. The minimum inhibitory concentration (MIC) of the Romanian propolis ethanolic extract ranged from 6 to 10 μg/mL for all isolates, determined by the broth microdilution method. The MICs of ethanolic Romanian propolis extracts had a pronounced antibacterial activity. These results indicate that propolis can potentially be used and recommended for in vivo experiments as a promising therapeutic agent against Staphylococcus aureus infections in superficial dermatitis of dogs.

Comparison of the Antioxidant Activity of Propolis Samples from Different Geographical Regions

Propolis composition depends on several factors. The classification of propolis is based on its geographical location, color and agricultural characteristics. It is also classified according to the flora where the bees collect the resins, which represent the raw material for propolis production. Propolis possesses high antioxidant activity determined by its phenolic compounds. Due to diverse composition and possible impact on human health, eight samples of propolis were evaluated for their phenolic composition and antioxidant activity. Samples of Polish, Romanian, Turkish and Uruguayan origin propolis were used for phenolic spectrum determination using high performance liquid chromatography and photodiode array detection and in vitro DPPH and ABTS methods were used to determine the antioxidant activity of the extracts. PCA and HCA models were applied to evaluate the correlation between isolated polyphenols and antioxidant activity. The results confirmed variability in propolis composition depending on the geographical region of collection and the plant sources, and correlation between chemical composition and antioxidant activity. Results of PCA and HCA analyses confirm that Polish propolis is similar to that from different provinces of Romania, while Turkish and Uruguay are completely different. Polish and Romanian propolis belong to the poplar type. The assessed phenolic compounds of propolis samples used in the study are responsible for its antioxidant effect. The observed antioxidant activity of the analyzed samples may suggest directing subsequent research on prophylactic and therapeutic properties concerning cardiovascular, metabolic, neurodegenerative, and cancerous diseases, which are worth continuing.

Fungal Community Investigation from Propolis Natural Products: Diversity and Antibacterial Activities Evaluation

Discovering new species and interesting bioactive metabolites from customary sources is becoming progressively laborious. Propolis constitutes the largest diversified reserve of microbial constituents in the beehive. However, fungal communities associated with these environments remain insufficiently established. We present the first detailed investigation of the cultivable fungal community associated with Tunisian propolis, and we evaluate its antibacterial properties against pathogenic bacteria. A total of 80 fungal strains were isolated from propolis samples derived from seven different Tunisian locations. The majority of the isolated fungi were classified as Ascomycota (97.5%), and only 2.5% belonged to Basidiomycota. Our collection was clustered into 15 genera, among which Coniochaeta (36.25%), Aspergillus (15%), Penicillium (13.75%), Cladosporium (10%), Fusarium (7.5%), Didymella (5%), and Alternaria (3.75%) were the most common. Evaluation of the antibacterial activity revealed that 25.6% of the total community showed a broad range of antibacterial activity. Particularly, the Penicillium griseofulvum CC8 strain has manifested the strongest inhibitory effects against all the tested bacteria.

Propolis characterization and antimicrobial activities against Staphylococcus aureus and Candida albicans: A review

Propolis is a plant-based sticky substance that is produced by honeybees. It has been used traditionally by ancient civilizations as a folk medicine, and is known to have many pharmaceutical properties including antioxidant, antibacterial, antifungal, anti-inflammatory, antiviral, and antitumour effects. Worldwide, researchers are still studying the complex composition of propolis to unveil its biological potential, and especially its antimicrobial activity against a variety of multidrug-resistant microorganisms. This review explores scientific reports published during the last decade on the characterization of different types of propolis, and evaluates their antimicrobial activities against Staphylococcus aureus and Candida albicans. Propolis can be divided into different types depending on their chemical composition and physical properties associated with geographic origin and plant sources. Flavonoids, phenols, diterpenes, and aliphatic compounds are the main chemicals that characterize the different types of propolis (Poplar, Brazilian, and Mediterranean), and are responsible for their antimicrobial activity. The extracts of most types of propolis showed greater antibacterial activity against Gram-positive bacteria: particularly on S. aureus, as well as on C. albicans, as compared to Gram-negative pathogens. Propolis acts either by directly interacting with the microbial cells or by stimulating the immune system of the host cells. Some studies have suggested that structural damage to the microorganisms is a possible mechanism by which propolis exhibits its antimicrobial activity. However, the mechanism of action of propolis is still unclear, due to the synergistic interaction of the ingredients of propolis, and this natural substance has multi-target activity in the cell. The broad-spectrum biological potentials of propolis present it as an ideal candidate for the development of new, potent, and cost-effective antimicrobial agents.

Land Use Influences the Composition and Antimicrobial Effects of Propolis

Simple Summary

Honey bees collect a multitude of substances from plants, including nectar, pollen, and a lesser-known resin called propolis. Honey bees line their colonies with propolis to fill in cracks and potentially aid in their defense against pathogens such as fungi, bacteria, and viruses. Different plants contain different types of chemicals that are collected by bees to form propolis, and so one would expect the plants that bees visit to influence the quality of the propolis contained within honey bee colonies. This project explored the chemical composition and antibacterial effects of propolis collected from apiaries that were surrounded by different types of land use patterns in Iowa. Propolis samples collected from colonies that were surrounded by the highest levels of agriculture had the lowest abundance of chemical compounds and also the lowest antimicrobial activity detected for two of the bacteria species studied. These results add to a growing body of work that suggests that high intensity agricultural land use negatively impacts multiple aspects of honey bee colony health.

Abstract

Honey bee propolis is a complex, resinous mixture created by bees using plant sources such as leaves, flowers, and bud exudates. This study characterized how cropland surrounding apiaries affects the chemical composition and antimicrobial effects of propolis. The chemical composition and compound abundance of the propolis samples were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) and the antimicrobial effects were analyzed using the 50% minimum inhibitory concentration (MIC₅₀) assay against four relevant bee pathogens, Serratia marcescens, Paenibacillus larvae, Lysinibacillus sphaericus, and Klebsiella pneumoniae. Propolis composition varied significantly with apiary, and cropland coverage predicted mean sum abundance of compounds. The apiary with the highest cropland coverage exhibited significantly higher MIC₅₀ values for S. marcescens and K. pneumoniae compared to other apiaries. These results demonstrate that agricultural land use surrounding honey bee apiaries decreases the chemical quality and antimicrobial effects of propolis, which may have implications for the impacts of land use on hive immunity to potential pathogens.

Physicochemical characterization and in vitro evaluation of the antioxidant and anticandidal activities of Moroccan propolis

Background and Aim:

Human mycotic infections are one of the major health problems worldwide. Prolonged use of antimycotic drugs has contributed to the development of resistance in pathogenic fungi. This study was conducted to examine antioxidant and anticandidal activities of Moroccan propolis.

Materials and Methods:

Two ethanolic extracts of Moroccan propolis from the Fez-Meknes region were evaluated regarding the following physicochemical parameters: Yield, pH, total carbohydrates, total proteins, total lipids, minerals, total phenolic content, total flavonoid content, and antioxidant activity using ferric reducing antioxidant power (FRAP) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. In addition, we assessed the in vitro anticandidal activity against vulvovaginal candidiasis strains, that is, Candida albicans, Candida glabrata, Candida parapsilosis, and Candida krusei, using the broth micromethod according to the CLSI/M27-A3 reference guidelines.

Results:

The propolis samples exhibited a mean yield of 16%, with an acidic pH ranging from 4.8 to 5.9; the sample from the Oued Amlil area (OAPEE) contained high levels of resin, balsam, moisture, total carbohydrates, and total lipids: 59.8%, 0.71%, 2%, 1.01 gGlcEq/g, and 120 mg/g, respectively. Moreover, the sample from the Sefrou area (SFPEE) was richer in total proteins and minerals, with values of 2.5 g/100 g and 1.84%, respectively. The total polyphenol and flavonoid content in the propolis extracts were 117.38 and 194.68 mg of gallic acid equivalent/g, and 17.45–27.79 mg of quercetin equivalent/g, respectively. Regarding the antioxidant activity, the most effective propolis extract was the sample from the Sefrou area, at 72.5 μg/mL and 118.78 μmoL Fe²⁺/g for ABTS-half-maximal inhibitory concentration and FRAP-half maximal effective concentration, respectively. The analysis of phenolic compounds using high-performance liquid chromatography with a diode-array detector revealed the presence of 13 polyphenols. The main compound in the OAPEE sample was epicatechin (310 mg/g), whereas in the SFPEE sample was apigenin (410 mg/g). Regarding the antifungal activity against Candida species, the minimum inhibitory concentration and minimum fungicidal concentration of the Moroccan propolis ethanolic extracts ranged between 31.2 and 62.5 μg/mL and 62.5 and 125 μg/mL, respectively, comparable with fluconazole (as a reference antimycotic).

Conclusion:

This study suggests that Moroccan propolis (31.2 and 125 μg/mL) may be an important source of bioactive molecules with anticandidal activity. Propolis may be a promising naturally-occurring candidate for the development of antimycotic drugs.

Antifungal Properties of Chemically Defined Propolis from Various Geographical Regions

Long-term fungal infections that are difficult to treat require new substances for their prevention, treatment, or as adjuvants during antibiotic therapy. Propolis is a very promising source of natural substances that show a wide range of pharmacological properties, including antifungal activity against various fungal strains. The purpose of the literature review was to summarize recent studies (PubMed, Scopus) on progress in evaluating the antifungal activity of chemically defined propolis extracts. During the selection of studies, only those with results of antifungal activity expressed as minimal inhibitory concentration (MIC) and/or minimal fungicidal concentration (MFC) were analyzed. Moreover, plant, animal and environmental factors influencing the chemical composition of propolis are discussed. Mechanisms of antifungal activity of propolis extracts and research trends in the aspect of developing new therapies and the assessment of drug interactions are indicated. The review of the research results shows that there is great progress in the definition of propolis extracts. After comparing the MIC/MFC values, it was assessed that propolis extracts offer a wide range of activity not only against pathogenic Candida strains but also against risky molds; however, the strength of this activity is varied.

Propolis: chemical diversity and challenges in quality control

Propolis is a resinous natural product produced by honeybees using beeswax and plant exudates. The chemical composition of propolis is highly complex, and varies with region and season. This inherent chemical variability presents several challenges to its standardisation and quality control. The present review was aimed at highlighting marker compounds for different types of propolis, produced by the species Apis mellifera, from different geographical origins and that display different biological activities, and to discuss strategies for quality control. Over 800 compounds have been reported in the different propolises such as temperate, tropical, birch, Mediterranean, and Pacific propolis; these mainly include alcohols, acids and their esters, benzofuranes, benzopyranes, chalcones, flavonoids and their esters, glycosides (flavonoid and diterpene), glycerol and its esters, lignans, phenylpropanoids, steroids, terpenes and terpenoids. Among these, flavonoids (> 140), terpenes and terpenoids (> 160) were major components. A broad range of biological activities, such as anti-oxidant, antimicrobial, anti-inflammatory, immunomodulatory, and anticancer activities, have been ascribed to propolis constituents, as well as the potential of these compounds to be biomarkers. Several analytical techniques, including non-separation and separation methods have been described in the literature for the quality control assessment of propolis. Mass spectrometry coupled with separation methods, followed by chemometric analysis of the data, was found to be a valuable tool for the profiling and classification of propolis samples, including (bio)marker identification. Due to the rampant chemotypic variability, a multiple-marker assessment strategy considering geographical and biological activity marker(s) with chemometric analysis may be a promising approach for propolis quality assessment.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11101-022-09816-1.

Propolis: Chemical Constituents, Plant Origin, and Possible Role in the Prevention and Treatment of Obesity and Diabetes

Honeybee products are not only beneficial to human health but also important to the food industry. One such product is propolis, a resinous substance that honeybees collect from certain trees and plants and store inside their hives. Although various health benefits of propolis have been reported, the chemical composition of propolis varies greatly depending on the growing region and plant origin. These differences have led to many misconceptions and conflicting research results. In this paper, we review research findings on how the growing region and plant origin of propolis affects its composition. We also discuss trends in research on the antiobesity and antidiabetes effects of propolis as well as recent findings that a major component of Brazilian green propolis modulates adipocyte function. Finally, we discuss challenges to be tackled in future research on the health benefits of propolis and share our perspective on the future of this field.

An insight into the botanical origins of propolis from permanent preservation and reforestation areas of southern Brazil

Brown propolis from permanent preservation and reforestation areas of southern Brazil have attracted international commercial interest and have a unique composition, although little is known about their botanical origins, which are the plant resins used by bee foragers to produce propolis. Hence, the volatile profiles of organic and non-organic brown propolis and resins of suspected botanical origins—Araucaria angustifolia, Pinus elliott and Pinus taeda—were determined using static headspace gas chromatography coupled to mass spectrometry (SHS-GCMS) and compared. Nighty nine volatiles were tentatively identified, and monoterpenes and sesquiterpenes were the most abundant classes. Principal component analysis (PCA) showed similarity between organic propolis and A. angustifolia volatile profiles (p < 0.05). Hierarchical clustering analysis showed singularities among propolis, even between propolis produced 1 km away from each other. Heatmaps were used to identify peaks present in similar relative intensities in both propolis and conifer resins. Hence, the approach using volatile profiles shed light to propolis botanical origins, which is important for authentication and traceability purposes.

Comparison of Ethanolic and Aqueous Populus balsamifera L. Bud Extracts by Different Extraction Methods: Chemical Composition, Antioxidant and Antibacterial Activities

The balsam poplar (Populus balsamifera L.) buds that grow in Lithuania are a polyphenol-rich plant material with a chemical composition close to that of propolis. In order to potentially adapt the extracts of this plant's raw material for therapeutic purposes, it is important to carry out detailed studies on the chemical composition and biological activity of balsam poplar buds. An important step is to evaluate the yield of polyphenols by different extraction methods and using different solvents. According to our research, extracts of balsam poplar buds collected in Lithuania are dominated by p-coumaric (496.9-13,291.2 µg/g), cinnamic acid (32.9-11,788.5 µg/g), pinobanksin (34.9-1775.5 µg/g) and salicin (215.3-1190.7 µg/g). The antioxidant activity of poplar buds was evaluated by the ABTS (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric-reducing antioxidant power) methods, all extracts showed antioxidant activity and the obtained results correlated with the obtained amounts of total phenolic compounds in the extracts (ABTS r = 0.974; DPPH r = 0.986; FRAP r = 0.955, p < 0.01). Studies of antimicrobial activity have shown that ethanolic extracts have an antimicrobal activity effect against Staphylococcus aureus, Enterococcus faecalis and Escherichia coli. The extracts showed a better antimicrobal activity against gram-positive bacteria.

Geographic Area of Collection Determines the Chemical Composition and Antimicrobial Potential of Three Extracts of Chilean Propolis

The biological properties of chilean propolis have been described and include antibacterial, antifungal and antibiofilm activities. Propolis has a strong antimicrobial potential. Clinical experiences with synthetic antibiotics indicated the need to discover new sources of bioactive compounds associated with ethnopharmacological knowledge or natural sources such as propolis. The microscopic analysis of pollen grains from plants allows us to determine the botanical origin of the propolis samples. In Angol, sample pollen grains were obtained from fodder plants (Sorghum bicolor; Lotus sp.) and trees, such as Acacia sp., Pinus radiata, Eucalyptus sp. and Salix babylonica. Propolis from the Maule region contains pollen grains from endemic plants such as Quillaja saponaria. Finally, the sample obtained from Melipilla presented a wider variety of pollen extracted from vegetable species.Colorimetric assays performed to quantify the total polyphenols present in Chilean propolis samples established that PCP2 (Angol sample) showed high amounts of phenolics compounds, with significant statistical differences in comparison with the other samples. The main compounds identified were pinocembrin, quercetin and caffeic acid phenethyl ester (CAPE). The Angol sample showed a high content of polyphenols.Studies that determine the influence of geographical and floral variables on the chemical composition of propolis are a valuable source of information for the study of its biological properties.

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.

Effects of Propolis on Infectious Diseases of Medical Relevance

Infectious diseases are a significant problem affecting the public health and economic stability of societies all over the world. Treatment is available for most of these diseases; however, many pathogens have developed resistance to drugs, necessitating the development of new therapies with chemical agents, which can have serious side effects and high toxicity. In addition, the severity and aggressiveness of emerging and re-emerging diseases, such as pandemics caused by viral agents, have led to the priority of investigating new therapies to complement the treatment of different infectious diseases. Alternative and complementary medicine is widely used throughout the world due to its low cost and easy access and has been shown to provide a wide repertoire of options for the treatment of various conditions. In this work, we address the relevance of the effects of propolis on the causal pathogens of the main infectious diseases with medical relevance; the existing compiled information shows that propolis has effects on Gram-positive and Gram-negative bacteria, fungi, protozoan parasites and helminths, and viruses; however, challenges remain, such as the assessment of their effects in clinical studies for adequate and safe use.

Extracts of Poplar Buds (Populus balsamifera L., Populus nigra L.) and Lithuanian Propolis: Comparison of Their Composition and Biological Activities

Balsam poplar and black poplar (Populus balsamifera L. and Populus nigra L.) buds that grow in Lithuania are the primary source of propolis, therefore it is proper to evaluate and compare the composition of these raw plant materials and propolis quantitatively and qualitatively. Propolis and balsamic poplar bud extract are dominated by p-coumaric acid and black poplar-caffeic acid. Antioxidant activity was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), FRAP (ferric-reducing antioxidant power) and CUPRAC (cupric reducing antioxidant capacity) methods and all extracts showed antioxidant activity, and obtained results correlated with the obtained amounts of phenolic compounds and flavonoids in the extracts. Studies of antimicrobial activity have shown that all extracts have a growth inhibitory effect against Staphylococcus aureus and Candida albicans, but the extract of balsam poplar buds showed the most significant effect of such kind. Considering the results of the research, it can be stated that balsam poplar buds cultured in Lithuania are the primary raw material of propolis, which is rich in phenolic compounds with antioxidant properties and is a promising raw material for pharmaceutical purposes.

Propolis in Metabolic Syndrome and Its Associated Chronic Diseases: A Narrative Review

Propolis is a resinous product collected by bees from plants to protect and maintain the homeostasis of their hives. Propolis has been used therapeutically by humans for centuries. This review article attempts to analyze the potential use of propolis in metabolic syndrome (MetS) and its associated chronic diseases. MetS and its chronic diseases were shown to be involved in at least seven out of the top 10 causes of death in 2019. Patients with MetS are also at a heightened risk of severe morbidity and mortality in the present COVID-19 pandemic. Propolis with its antioxidant and anti-inflammatory properties is potentially useful in ameliorating the symptoms of MetS and its associated chronic diseases. The aim of this article is to provide a comprehensive review on propolis and its therapeutic benefit in MetS and its chronic diseases, with an emphasis on in vitro and in vivo studies, as well as human clinical trials. Moreover, the molecular and biochemical mechanisms of action of propolis are also discussed. Propolis inhibits the development and manifestation of MetS and its chronic diseases by inhibiting of the expression and interaction of advanced glycation end products (AGEs) and their receptors (RAGEs), inhibiting pro-inflammatory signaling cascades, and promoting the cellular antioxidant systems.