Determination of antioxidant activity and phenolic compounds for basic standardization of Turkish propolis

The Influence of Geographical Origin on Poplar Propolis Composition and the Impact of Human Microbiota

Ethanol extracts obtained from 13 poplar propolis samples originating from various European countries by traditional maceration were tested for total polyphenols, flavonoid content, and antioxidant activity. Moreover, the content of 18 polyphenolic compounds (from the group of phenolic acids and flavonoids) was determined using the HPLC method. The inhibitory effect of six selected extracts with the highest activity was assessed by well-diffusion method against five strains (Bifidobacterium spp., L. rhamnosus, L. acidophilus, E. coli, and Bacteroides spp.) of intestinal bacteria self-isolated from the faeces of obese probands with the use of selective media. It was found that the antioxidant activity of propolis varied depending on geographical origin and even among samples from the same region, which indicates that some other factors also influence propolis quality. The samples of different geographical origin varied mainly in the share of individual phenolic compounds, and it was not possible to find a characteristic marker of origin, excluding the galangin present in the Polish samples only. Assessing the inhibitory activity of propolis (in the range of 70 mg to 10 µg per mL) indicated that the concentration of 100 µg/mL was found as being safe for tested fecal bacteria (Bifidobacterium spp., L. rhamnosus, L. acidophilus, E. coli, and Bacteroides spp.). As no negative effect of low doses of propolis on the intestinal microflora was found, it can be suggested that its use in recommended doses brings only beneficial effects to the body.

Phenolic Composition, Antiradical, Antimicrobial, and Anti-Inflammatory Activities of Propolis Extracts from North East Spain

Antioxidant-related parameters and anti-inflammatory and antimicrobial activities against Listeria monocytogenes were assessed in eight North East Spain poplar propolis samples. Propolis extracts (PEs) were obtained using 70% ethanol (PEE) and methanol (PME). Yield and total phenol compounds were higher in PEE. Phenolic acids were analyzed by a high-performance liquid chromatograph-diode array detector. Caffeic and ferulic acids were quantified in all PEE and PME. All samples contained p-coumaric acid (quantified in 6 PEE and in 3 PME). Ascorbic acid was detected in all propolis, but mainly quantified in PME (≤0.37 mg/g PE). Biological properties were tested on PEE. As for antiradical activities, trolox equivalent antioxidant capacity (TEAC) [against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)•+], ranged between 578 and 4620 µmol trolox/g, 2,2-diphenyl-1-picrylhydrazyl (DPPH) (against DPPH free radical), between 0.049 and 0.094 mg/mL, antioxidant activity against hydroxyl (•OH) radical (AOA), between 0.04 and 11.01 mmol uric acid/g, and oxygen radical absorbance capacity (ORAC) against peroxyl (ROO•) radical between 122 and 3282 µmol trolox/g. Results of TEAC, AOA, and ORAC were significantly correlated. IC50 anti-inflammatory activity ranged from 1.08 to 6.19 mg/mL. Propolis showed higher inhibitory activity against L. monocytogenes CECT934 and L. monocytogenes CP101 by agar well diffusion (P < .05) (10.5 and 10.2 mm, respectively) than against L. monocytogenes CP102 (7.0 mm). Data of this research show that North East Spain propolis may be of interest for pharmaceutical and food industry use.

Interaction of olive oil-based propolis and caffeic acid phenethyl ester with methylprednisolone used in the treatment of human acute myeloid leukemia

BACKGROUND

Methylprednisolone (MP) is a pharmaceutical agent employed in the management of Leukemia, which is a systemic malignancy that arises from abnormalities in the hematological system. Numerous investigations in the field of cancer research have directed their attention towards propolis, a natural substance with significant potential as a treatment-supportive agent. Its utilization aims to mitigate the potential adverse effects associated with chemotherapy medications. The objective of this study was to examine the impact of olive oil-based propolis (OEP) and caffeic acid phenethyl ester (CAPE) on the treatment of acute myeloid leukemia, as well as to determine if they exhibit a synergistic effect when combined with the therapeutic support product methylprednisolone.

METHODS AND RESULTS

The proliferation of HL-60 cells was quantified using the WST-8 kit. The PI Staining technique was employed to do cell cycle analysis of DNA in cells subjected to OEP, CAPE, and MP, with subsequent measurement by flow cytometry. The apoptotic status of cells was determined by analyzing them using flow cytometry after staining with the Annexin V-APC kit. The quantification of apoptotic gene expression levels was conducted in HL-60 cells. In HL-60 cells, the IC50 dosages of CAPE and MP were determined to be 1 × 10- 6 M and 5 × 10- 4 M, respectively. The HL-60 cells were subjected to apoptosis and halted in the G0/G1 and G2/M phases of the cell cycle after being treated with MP, CAPE, and OEP.

CONCLUSIONS

Propolis and its constituents have the potential to serve as effective adjunctive therapies in chemotherapy.

Biological Activity and Chemical Composition of Propolis Extracts with Potential Use in Vulvovaginal Candidiasis Management

Environmental sustainability is an increasing challenge in the pharmaceutical field, leading to the search for eco-friendly active ingredients. Among natural ingredients, propolis arises as an excellent alternative, being a complex substance with pharmacological properties. This work aims to explore the potential of propolis as a new pharmaceutical ingredient for the replacement of conventional vulvovaginal antifungals. Propolis extracts were obtained by Ultrasound-Assisted Extraction using different solvents (water, water/ethanol (50:50, v/v), and ethanol). Afterwards, the extracts were characterized regarding total phenolic content (TPC), antioxidant/antiradical activities, radical scavenging capacity, antifungal activity against strains of Candida species, and viability effect on two female genital cell lines. The aqueous extract achieved the best TPC result as well as the highest antioxidant/antiradical activities and ability to capture reactive oxygen species. A total of 38 phenolic compounds were identified and quantified by HPLC, among which ferulic acid, phloridzin and myricetin predominated. Regarding the anti-Candida spp. activity, the aqueous and the hydroalcoholic extracts achieved the best outcomes (with MIC values ranging between 128 and 512 μg/mL). The cell viability assays confirmed that the aqueous extract presented mild selectivity, while the hydroalcoholic and alcoholic extracts showed higher toxicities. These results attest that propolis has a deep potential for vulvovaginal candidiasis management, supporting its economic valorization.

Propolis Protects GC-1spg Spermatogonial Cells against Tert-Butyl Hydroperoxide-Induced Oxidative Damage

Propolis is a natural resin produced by honeybees with plenty of pharmacologic properties, including antioxidant activity. Oxidative stress disrupts germ cell development and sperm function, with demonstrated harmful effects on male reproduction. Several natural antioxidants have been shown to reduce oxidative damage and increase sperm fertility potential; however, little is known about the effects of propolis. This work evaluated the role of propolis in protecting spermatogonial cells from oxidative damage. Propolis' phytochemical composition and antioxidant potential were determined, and mouse GC-1spg spermatogonial cells were treated with 0.1-500 µg/mL propolis (12-48 h) in the presence or absence of an oxidant stimulus (tert-butyl hydroperoxide, TBHP, 0.005-3.6 µg/mL, 12 h). Cytotoxicity was assessed by MTT assays and proliferation by Ki-67 immunocytochemistry. Apoptosis, reactive oxygen species (ROS), and antioxidant defenses were evaluated colorimetrically. Propolis presented high phenolic and flavonoid content and moderate antioxidant activity, increasing the viability of GC-1spg cells and counteracting TBHP's effects on viability and proliferation. Additionally, propolis reduced ROS levels in GC-1spg, regardless of the presence of TBHP. Propolis decreased caspase-3 and increased glutathione peroxidase activity in TBHP-treated GC-1spg cells. The present study shows the protective action of propolis against oxidative damage in spermatogonia, opening the possibility of exploiting its benefits to male fertility.

Starch nanoparticles containing phenolic compounds from green propolis: Characterization and evaluation of antioxidant, antimicrobial and digestibility properties

This study investigated the production of nanoparticles through nanoprecipitation using cassava and potato starches as carriers to stabilize phenolic compounds (PC) from green propolis extract (PE). Additionally, the antioxidant and antimicrobial activities of PC stabilized with starch nanoparticles (SNPs), as well as their release under gastrointestinal conditions were investigated. PE exhibited antioxidant and antibacterial properties, especially PE3 (PE produced using sonication by 20 min and stirring at 30 °C for 24 h) had the highest concentrations of p-coumaric acid, rutin, kaempferol and quercetin. SNPs displayed bimodal distribution with particle size lower than 340 nm. The stabilization of PC increased surface charge and hydrophobicity in SNPs. Moreover, SNPs containing PC from PE exhibited antibacterial activity against Listeria monocytogenes, at a concentration of 750 mg/mL. Low release of PC was observed from the nanoparticles when exposed under simulated gastrointestinal conditions. These nanomaterials could be used as natural ingredients with antioxidant and antimicrobial properties.

Combination of UHPLC-MS/MS with context-specific network and cheminformatic approaches for identifying bioactivities and active components of propolis

Discovering new bioactivities and identifying active compounds of food materials are major fields of study in food science. However, the process commonly requires extensive experiments and can be technically challenging. In the current study, we employed network biology and cheminformatic approaches to predict new target diseases, active components, and related molecular mechanisms of propolis. Applying UHPLC-MS/MS analysis results of propolis to Context-Oriented Directed Associations (CODA) and Combination-Oriented Natural Product Database with Unified Terminology (COCONUT) systems indicated atopic dermatitis as a novel target disease. Experimental validation using cell- and human tissue-based models confirmed the therapeutic potential of propolis against atopic dermatitis. Moreover, we were able to find the major contributing compounds as well as their combinatorial effects responsible for the bioactivity of propolis. The CODA/COCONUT system also provided compound-associated genes explaining the underlying molecular mechanism of propolis. These results highlight the potential use of big data-driven network biological approaches to aid in analyzing the impact of food constituents at a systematic level.

Chemical and Functional Characterization of Propolis Collected from Different Areas of South Italy

This study investigated the chemical and functional characterization of propolis collected in southern Italy, in particular in Basilicata, a region rich in ecological and vegetative biodiversity. Sixteen samples of propolis, collected within a radius of 40 km from each other in the Basilicata region, showed significant differences between the chemical and functional parameters investigated: color index (L*, a*, b*; p < 0.05) and variation in chemical composition and antioxidant activities by ABTS and FRAP assays. In general, Lucanian propolis had a low content of waxes (p < 0.05) and a high content of resin (p < 0.05) and balsams (p < 0.05). The content of the total phenolic compounds and flavonoids was highly variable, as was the biological capacity. In conclusion, Lucanian propolis showed remarkable variability, highlighting significant diversification according to the geographical position and the diversity of the flora surrounding the apiary that the bees use as a source of resin. This study, therefore, contributes to the enhancement of the quality of propolis, laying the foundations for the production and marketing of propolis not only in the food industry but also in the pharmaceutical and cosmetic industries.

Characteristics of Phenolic Compounds in Peucedanum japonicum According to Various Stem and Seed Colors

Total polyphenol and total flavonoid assays were performed to characterize the relationships between the color of Peucedanum japonicum (PJ) seed coat and stem and the content of phytochemical compounds. The samples were divided into two groups based on their stem and seed coat color, with each group containing 23 samples. The stem color group was subdivided into green, light red, and red, whereas the seed coat color group was divided into light brown, brown, and dark brown. In the stem color group, the light red stems exhibited the highest content of phytochemical compounds, with levels over 10% higher than those of the stems of the other colors. Moreover, among the top ten samples with the highest total polyphenol content, eight samples were light red, and the light red group also exhibited the highest total flavonoid content among the examined color groups. In terms of the seed coat color, the plants grown from dark brown seeds exhibited the highest contents of both total polyphenols and total flavonoids. In conclusion, PJ plants with dark brown seeds and light red stems contained the highest levels of phytochemical compounds. Collectively, our findings provide a valuable basis for future seed selection of PJ for pharmaceutical purposes.

Inhibitory Effects of Polyphenol- and Flavonoid-Enriched Rice Seed Extract on Melanogenesis in Melan-a Cells via MAPK Signaling-Mediated MITF Downregulation

Melanin production is an important process that prevents the host skin from harmful ultraviolet radiation; however, an overproduction of melanin results in skin diseases. In the present study, we determined the antioxidative and anti-melanogenic activities of polyphenol- and flavonoid-enriched rice seed extracts in melan-a cells. The polyphenol and flavonoid content of Hopum (HP) and Sebok (SB) rice seed extracts was measured. The antioxidant capacity was determined using the ABTS radical scavenging method. SB contained high amounts of polyphenols and flavonoids, which significantly increased antioxidative activity compared with HP. Various concentrations of these extracts were evaluated in a cytotoxicity using melan-a cells. At 100 µg/mL, there was no significant difference for all treatments compared with untreated cells. Therefore, 100 µg/mL was selected as a concentration for the further experiments. SB significantly suppressed the phosphorylation/activation of p-38 MAPK, increased the expression of phosphorylated ERK 1/2 and Akt, and downregulated the microphthalmia-associated transcription factor (MITF). This resulted in decreased levels of tyrosinase and tyrosinase-related protein-1 and -2. These results indicate the potential of polyphenol- and flavonoid-enriched rice seed as a treatment for hyperpigmentation.

Phenolic Content and Bioactivity as Geographical Classifiers of Propolis from Stingless Bees in Southeastern Mexico

Propolis collected by stingless bees is a valuable biocultural resource and a source of bioactive compounds. Methodologies to establish both the geographic origin and the potential pharmacological activity of propolis of stingless bees are required to regulate their sustainable use. The aim of this study was to classify Melipona beecheii propolis according to its phenolic compound content and potential pharmacological activity, using in vitro assays and statistical methodologies of multivariate analysis, hierarchical cluster analysis, and principal component analysis. Propolis samples were collected from seven states in southeastern Mexico. Total phenolic content and flavonoids were determined spectrophotometrically, and antioxidant, anti-inflammatory, and antimicrobial activities were evaluated. Both total phenolic content and flavonoids, and in vitro bioactivity potential of propolis extracts showed significant variations. Multivariate analysis, hierarchical cluster analysis, and principal component analysis enabled us to distinguish and classify propolis produced by M. beecheii according to similarity in terms of total phenolic content, in vitro bioactivity potential, and geographical origin. This strategy could be used to establish regulations for sustainable use, marketing, and industrial applications.

Protective Effect of Thyme and Chestnut Honeys Enriched with Bee Products against Benzo(a)pyrene-Induced DNA Damage

The aim of the present study was to validate the cytotoxicity, genotoxicity, and preventive potential against benzo(a)pyrene (BaP)-induced DNA damage of nine samples of thyme and chestnut honeys enriched with bee products (royal jelly and propolis, 2-10%). Cell viability was determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay (0-250 mg/mL) to select nontoxic concentrations, and DNA damage (0.1-10 μg/mL) was evaluated by the alkaline single-cell gel electrophoresis or comet assay. Treatment with honey samples or royal jelly and propolis did not affect the viability of HepG2 cells up to 100 and 50 mg/mL, respectively. Treatment with 100 μM BaP significantly increased (p ≤ 0.001) the levels of the DNA strand breaks. None of the tested concentrations (0.1-10 μg/mL) of the honey samples (thyme and chestnut), royal jelly, and propolis caused DNA damage per se. All tested samples at all the concentrations used decreased the genotoxic effect of BaP. In addition, all mixtures of thyme or chestnut honeys with royal jelly or propolis showed a greater protective effect against BaP than the samples alone, being the thyme and chestnut honey samples enriched with 10% royal jelly and 10% propolis the most effective (70.4% and 69.4%, respectively). The observed protective effect may be associated with the phenolic content and antioxidant capacity of the studied samples. In conclusion, the thyme and chestnut honey samples enriched with bee products present potential as natural chemoprotective agents against the chemical carcinogen BaP.

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.

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.

Anti-Allergic Properties of Propolis: Evidence From Preclinical and Clinical Studies

Allergic diseases are a global health burden with increasing prevalence. Side effects of available medications (antihistamines and steroids), lack of patients' perceived effectiveness and high cost of biologic therapies (omalizumab) are challenges to the clinical management of allergic diseases. As allergy symptoms persist for a long time, complementary and alternative medicine (CAM) such as propolis may be considered a potential prophylactic or therapeutic option to avoid long-term medication use. Propolis is a natural resinous substance produced by bees. Although propolis is well known to possess antioxidant, antimicrobial, and anticancer properties, its anti-allergic potential is not fully explored. Several preclinical studies demonstrated the therapeutic effects of propolis extracts against allergic inflammation, asthma, allergic rhinitis, atopic dermatitis, and food allergy, which may be partly attributed to their inhibitory effects on the activation of mast cells and basophils. Clinically, the consumption of propolis as a supplement or an adjunct therapy is safe and attenuates various pathological conditions in asthma. Such an approach may be adopted for atopic dermatitis and allergic rhinitis. Although flavonoids (chrysin, kaempferol, galangin, and pinocembrin) and cinnamic acid derivatives (artepillin C and caffeic acid phenethyl ester) can contribute to the anti-allergic activities, they may not be present in all propolis samples due to variations in the chemical composition. Future studies should relate the anti-allergic activity of propolis with its chemical contents. This mini-review summarizes and discusses existing preclinical and clinical studies reporting the anti-allergic activities of propolis to provide insights into its potential applications in allergic diseases.

Recent Advances in Biological Activity, New Formulations and Prodrugs of Ferulic Acid

Trans-ferulic acid (FA) is a derivative of 4-hydroxycinnamic acid, which is found in many food products, fruits and beverages. It has scientifically proven antioxidant, anti-inflammatory and antibacterial properties. However, its low ability to permeate through biological barriers (e.g., the blood-brain barrier, BBB), its low bioavailability and its fast elimination from the gastrointestinal tract after oral administration limit its clinical use, e.g., for the treatment of neurodegenerative diseases, such as Alzheimer's disease. Therefore, new nanotechnological approaches are developed in order to regulate intracellular transport of ferulic acid. The objective of this review is to summarize the last decade's research on biological properties of ferulic acid and innovative ways of its delivery, supporting pharmacological therapy.

Galangin alleviates vascular dysfunction and remodelling through modulation of the TNF-R1, p-NF-κB and VCAM-1 pathways in hypertensive rats

Galangin is a natural flavonoid isolated from ginger, honey and propolis.

AIMS

To investigate the effect of galangin on blood pressure, vascular changes, sympathoexcitation, oxidative stress and inflammation in rats treated with N^G-nitro-l-arginine methyl ester (l-NAME).

MATERIALS AND METHODS

Male Wistar rats (220-250 g) were given l-NAME (0.5 mg/mL in drinking water) to induce hypertension for 5 weeks. They were treated with vehicle, galangin (30 or 60 mg/kg), or amlodipine (10 mg/kg) for the final two weeks (n = 6/group).

KEY FINDINGS

Galangin significantly reduced blood pressure and improved the impairment of endothelium-dependent vasodilation in hypertensive rats. Sympathoexcitation, including enhancement of contractile responses to electrical field stimulation, increases in intensity of tyrosine hydroxylase and plasma norepinephrine concentration in hypertensive rats, was attenuated by galangin treatment. Galangin also reduced systemic and vascular oxidative damage and increased plasma nitric oxide levels in the hypertensive groups. Aortic remodelling accompanied by aortic wall hypertrophy and fibrosis observed in hypertensive rats were alleviated by galangin treatment. Furthermore, galangin exhibited an anti-inflammatory effect by suppressing the upregulation of tumour necrosis factor receptor 1 (TNF-R1), phospho-nuclear factor kappa B (p-NF-κB) and vascular cell adhesion protein 1 (VCAM-1) in aortic tissue and reducing plasma tumour necrosis factor alpha (TNF-α) in l-NAME rats. In conclusion, galangin had antihypertensive effects that were relevant to attenuating endothelial dysfunction, sympathoexcitation and vascular remodelling. These effects might be contributed by antioxidant and anti-inflammatory capacities and modulation of the TNF-R1, p-NF-κB and VCAM-1 pathways in hypertensive rats.