Antioxidant activities and molecular mechanisms of the ethanol extracts of Baccharis propolis and Eucalyptus propolis in RAW64.7 cells

Chemical Analysis and in Vitro Antiviral Effects of Northeast Türkiye Propolis Samples against HSV-1

Propolis is one of the mixtures with the widest biological activity among natural products used in complementary medicine. HSV-1 is a highly contagious and endemic virus. Available drugs are insufficient for recurrent HSV-1 infections. Therefore, new approaches to treat HSV-1 infections are still being developed. In this study, it was aimed to investigate the inhibition effect of ethanolic Anatolian propolis extracts obtained from the Eastern Black Sea Region (Pazar, Ardahan, and Uzungöl) on HSV-1. In addition to the total phenolic (TPC) and the total flavonoid content (TFC), the phenolic profiles of the extracts were analyzed by HPLC-UV. The antiviral activity of the extracts were tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), quantitative Real Time Polymerase Chain Reaction (qRT-PCR), and plaque reduction tests, and the results were evaluated statistically. It was determined that the total amount of phenolic substances varied between 44.12 and 166.91 mg GAE/g, and the total flavonoid content of the samples varied between 12.50 and 41.58 (mg QUE/g). It was shown that all propolis samples used in the current study were effective against HSV-1, but the higher phenolic compounds contained in the samples showed the higher activity. The results show that ethanolic propolis extracts are promising candidates for HSV-1 treatment.

Ethanol extract of propolis regulates type 2 diabetes in mice via metabolism and gut microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis is a traditional natural medicine with various activities such as antioxidant and anti-inflammatory, immunomodulatory, anti-tumour, gastroenteritis treatment and prevention, anti-microbial and parasitic, as well as glucose regulation and anti-diabetes, and is expected to be an anti-diabetic candidate with few side effects, but the mechanism of action of propolis on type 2 diabetes mellitus (T2DM) has not been fully elucidated.

AIM OF THE STUDY

The purpose of this study was to investigate the mechanism of the effect of ethanol extract of propolis (EEP) on the regulation of blood glucose in T2DM mice.

MATERIALS AND METHODS

We studied the possible mechanism of EEP on T2DM using an animal model of T2DM induced by a combination of a high-fat diet and intraperitoneal injection of streptozotocin (STZ). The experiment was divided into four groups, namely, the normal group (HC), model group (T2DM), EEP and metformin group (MET). Biochemical indexes and cytokines were measured, and the differences of metabolites in the serum were compared by ¹H-NMR. In addition, the diversity of intestinal flora in feces was studied by 16S rDNA amplicon sequencing.

RESULTS

The results showed that following treatment with EEP and MET, the weight-loss trend of mice was alleviated, and the fasting blood glucose, insulin secretion level, insulin resistance index, C peptide level and oral glucose tolerance level decreased, whereas the insulin sensitivity index increased, thereby EEP effectively alleviated the occurrence of T2DM and insulin resistance. Compared with the T2DM group, the concentrations of pro-inflammatory cytokines interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) decreased significantly in EEP and MET groups, whereas the concentrations of anti-inflammatory cytokine interleukin-10 (IL-10) increased significantly. Metabolomics results revealed that EEP and MET regulate carbohydrate metabolism and restore amino acid and lipid metabolism. Correlation analysis of intestinal flora in mouse feces showed that compared with the HC group, harmful bacteria such as Bilophila, Eubacterium_ventriosum_group, Mucispirillum and Desulfovibrio were found in the T2DM group, whereas the abundance of beneficial bacteria such as Lactobacillus was significantly reduced. Parabacteroides, Akkermansia, Leuconostoc, and Alloprevotella were abundantly present in the EEP group; however, the MET group showed an increase in the genus Parasutterella, which could regulate energy metabolism and insulin sensitivity.

CONCLUSIONS

The results showed that EEP and MET reduce fasting blood glucose in T2DM mice, followed by alleviating insulin resistance, improving the inflammatory reaction of mice, regulating the metabolism of mice, and affecting the steady state of gut microbiota. However, the overall therapeutic effect of EEP is better than that of MET.

The effect of Brazilian Green Propolis extract on inflammation in patients with chronic kidney disease on peritoneal dialysis: A randomised double-blind controlled clinical trial

BACKGROUND

Chronic kidney disease (CKD) patients on dialysis display a low-grade systemic inflammatory burden. Nutritional interventions designed to activate the cytoprotective nuclear factor erythroid-2-related factor 2 (Nrf2) and inhibit nuclear factor-kB (NF-κB) have been proposed to mitigate this burden. Several bioactive compounds have been investigated to achieve this, including propolis, a resin produced by Apis mellifera bees. Considering the safety and efficacy of propolis, it could be a strategy to benefit these patients. Still, there are no studies using propolis in patients with CKD on peritoneal dialysis (DP), and clinical studies to support this application are lacking.

HYPOTHESIS/PURPOSE

The objective and novelty of the present study are to evaluate the effects of propolis supplementation on inflammatory markers in patients with CKD on PD.

STUDY DESIGN

A longitudinal, double-blind, placebo-controlled trial with CKD patients on PD.

METHODS

The patients were randomised into two groups: propolis that received four capsules of 100 mg (400 mg/day), containing concentrated and standardised dry EPP-AF® Brazilian green propolis extract) or placebo, four capsules of 100 mg (400 mg/day), of magnesium stearate, silicon dioxide, and microcrystalline cellulose, for two months. Plasma levels of inflammatory cytokines, including tumour necrosis factor (TNF-α) and interleukin-6 (IL-6), were evaluated by ELISA. Quantitative real-time PCR analyses were performed to evaluate the transcriptional expression levels of Nrf2 and NF-κB in peripheral blood mononuclear cells (PBMCs). Plasma malondialdehyde (MDA) levels, a lipid peroxidation marker, was measured as thiobarbituric acid reactive substances (TBARS). Routine biochemical markers, including C-reactive protein (CRP), were analysed using commercial kits. Carotid Intima-Media Thickness (CIMT) was measured with a doppler ultrasonography device. The study was registered on ClinicalTrials.gov under the number NCT04411758.

RESULTS

A total of 19 patients completed the study, ten patients in the propolis group (54 ± 1.0 years, five men, 7.2  (5.1) months on PD) and 9 in the placebo group (47.5 ± 15.2 years, three men, 10.8  (24.3) months on PD). The plasma levels of TNF-α reduced significantly (p = 0.02), and expression of Nrf2 showed a trend to increase (p = 0.07) after propolis supplementation.

CONCLUSION

EPP-AF® Green Propolis extract (400 mg/day) supplementation for two months appears as a potential strategy to mitigate inflammation, reducing TNF-α plasma levels in CKD patients on PD.

Development and Characterization of Films with Propolis to Inhibit Mold Contamination in the Dairy Industry

Due to the number of polyphenols with multiple biological activities, propolis has high potential to be used as an active agent in food protective films. Therefore, this study aimed to develop and characterize a sodium alginate film with ethanolic extract of propolis (EEP) for its potential use as protective active packaging against filamentous fungi in ripened cheese. Three different concentrations of EEP were analyzed: 0, 5 and 10% w/v. The films obtained were characterized, assessing thermal and physicochemical properties, as well as the concentration of polyphenols in the EEP and antifungal activity of the active films. The incorporation of EEP in the films generated thermal stability with respect to the loss of mass. Total color values (ΔE) of the films were affected by the incorporation of the different concentrations of EEP, showing a decrease in luminosity (L*) of the films, while the chromatic parameters a* and b* increased in direct proportion to the EEP concentration. Antifungal activity was observed with a fungistatic mode of action, stopping the growth of the fungus in cheeses without development of filamentous molds, thus increasing the shelf life of the ripened cheese under the analytical conditions, over 30 days at room temperature. Overall, EEP can be used to prevent growth and proliferation of spoilage microorganisms in cheese.

Comparing the Effects of Encapsulated and Non-Encapsulated Propolis Extracts on Model Lipid Membranes and Lactic Bacteria, with Emphasis on the Synergistic Effects of Its Various Compounds

Propolis is a resinous compound made by bees with well-known biological activity. However, comparisons between encapsulated and non-encapsulated propolis are lacking. Therefore, the antibacterial activity, effect on the phase transition of lipids, and inhibition of UV-induced lipid oxidation of the two forms of propolis were compared. The results showed that non-encapsulated propolis produces quicker effects, thus being better suited when more immediate effects are required (e.g., antibacterial activity). In order to gain an in-depth introspective on these effects, we further studied the synergistic effect of propolis compounds on the integrity of lipid membranes. The knowledge of component synergism is important for the understanding of effective propolis pathways and for the perspective of modes of action of synergism between different polyphenols in various extracts. Thus, five representative molecules, all previously isolated from propolis (chrysin, quercetin, trans-ferulic acid, caffeic acid, (-)-epigallocatechin-3-gallate) were mixed, and their synergistic effects on lipid bilayers were investigated, mainly using DSC. The results showed that some compounds (quercetin, chrysin) exhibit synergism, whereas others (caffeic acid, t-ferulic acid) do not show any such effects. The results also showed that the synergistic effects of mixtures composed from several different compounds are extremely complex to study, and that their prediction requires further modeling approaches.

Allergic Inflammation: Effect of Propolis and Its Flavonoids

The incidence of allergic diseases and their complications are increasing worldwide. Today, people increasingly use natural products, which has been termed a "return to nature". Natural products with healing properties, especially those obtained from plants and bees, have been used in the prevention and treatment of numerous chronic diseases, including allergy and/or inflammation. Propolis is a multi-component resin rich in flavonoids, collected and transformed by honeybees from buds and plant wounds for the construction and adaptation of their nests. This article describes the current views regarding the possible mechanisms and multiple benefits of flavonoids in combating allergy and allergy-related complications. These benefits arise from flavonoid anti-allergic, anti-inflammatory, antioxidative, and wound healing activities and their effects on microbe-immune system interactions in developing host responses to different allergens. Finally, this article presents various aspects of allergy pathobiology and possible molecular approaches in their treatment. Possible mechanisms regarding the antiallergic action of propolis on the microbiota of the digestive and respiratory tracts and skin diseases as a method to selectively remove allergenic molecules by the process of bacterial biotransformation are also reported.

Computational Study of Asian Propolis Compounds as Potential Anti-Type 2 Diabetes Mellitus Agents by Using Inverse Virtual Screening with the DIA-DB Web Server, Tanimoto Similarity Analysis, and Molecular Dynamic Simulation

Propolis contains a wide range of pharmacological activities because of their various bioactive compounds. The beneficial effect of propolis is interesting for treating type-2 diabetes mellitus (T2DM) owing to dysregulation of multiple metabolic processes. In this study, 275 of 658 Asian propolis compounds were evaluated as potential anti-T2DM agents using the DIA-DB web server towards 18 known anti-diabetes protein targets. More than 20% of all compounds could bind to more than five diabetes targets with high binding affinity (<−9.0 kcal/mol). Filtering with physicochemical and pharmacokinetic properties, including ADMET parameters, 12 compounds were identified as potential anti-T2DM with favorable ADMET properties. Six of those compounds, (2R)-7,4′-dihydroxy-5-methoxy-8-methylflavone; (RR)-(+)-3′-senecioylkhellactone; 2′,4′,6′-trihydroxy chalcone; alpinetin; pinobanksin-3-O-butyrate; and pinocembrin-5-methyl ether were first reported as anti-T2DM agents. We identified the significant T2DM targets of Asian propolis, namely retinol-binding protein-4 (RBP4) and aldose reductase (AKR1B1) that have important roles in insulin sensitivity and diabetes complication, respectively. Molecular dynamic simulations showed stable interaction of selected propolis compounds in the active site of RBP4 and AKR1B1. These findings suggest that Asian propolis compound may be effective for treatment of T2DM by targeting RBP4 and AKR1B1.

Neutralizing the free radicals could alleviate the disease severity following an infection by positive strand RNA viruses

Free radical release due to oxidative stress is gaining importance in the field of viral pathogenesis. Recent studies suggest the involvement of oxidative stress and ROS levels in regulating disease virulence during RNA virus infection. Most of the RNA virus infections lead to vascular dysfunction and disease severity. However, the biology of free radicals in maintaining vascular endothelium integrity is not completely understood. In the present review, we discuss some of the common features in positive-strand RNA virus infections such as dengue and SARS-CoV-2 and suggest that anti-oxidant therapy could pave the way to develop therapeutic strategies in combating emerging and re-emerging RNA viruses.

In-vitro antioxidant, in-vivo anti-inflammatory, and acute toxicity study of Indonesian propolis capsule from Tetragonula sapiens

Propolis is widely used as traditional medicine since ancient times. It was necessary to conduct the pre-clinical study because of its relevant curative properties. This study aimed to investigate in-vitro antioxidant, standardize quality parameters, study acute toxicity, and determine in-vivo anti-inflammatory. Three spectrophotometric methods were used to determine antioxidant activity. The standardization includes physical, chemical, and microbiological evaluation. Furthermore, an acute toxicity test was conducted using 20 female Sprague Dawley (SD) strain rats divided into 4 groups with different dose of propolis. The in vivo anti-inflammatory test was carried out using the carrageenan induction method on rats' soles. A total of 36 female SD rats were classified into 6 groups as follows, Group normal, negative control, diclofenac sodium, and three propolis groups (72; 144; and 288 mg/kg BW). The results demonstrated the IC₅₀ values of the DPPH and ABTS scavenging activity 9.694 ppm and 2.213 ppm, respectively. The FRAP reducing power was 189.05 mg AaE/g. The physical appearance of propolis capsule was vegicaps as white – white, size 0, with light brown granule. Moreover, the content weight was 418.88 mg with a disintegration time of 7 min 53 s, while the water, flavonoid, and polyphenol contents were 9.07%, 1.59%, and 98.0821 mg GAE/g respectively. The content of heavy metal and microbial contamination were not detected. The acute toxicity results showed LD₅₀ ≥ 5 g/kg BW, no toxicity symptoms, and no abnormalities in all rats. The anti-inflammatory inhibition percentage for groups III, IV, V, and VI was 11.86%, 6.53%, 7.81%, and 6.63% respectively, while the anti-inflammatory drugs effectiveness percentage compared to positive controls were 55.00%, 65.83%, and 55.83% respectively. Based on these results, it can be concluded that propolis capsules fulfilled the standardization requirements, and it is likely to be non-toxic, and effective as antioxidant and anti-inflammatory.

Propolis supplementation in obese patients with non-alcoholic fatty liver disease: effects on glucose homeostasis, lipid profile, liver function, anthropometric indices and meta-inflammation

Possible mechanisms of action of propolis in the management of NAFLD.

Effects of Bee Propolis on FBG, HbA1c, and Insulin Resistance in Healthy Volunteers

Objectives

Bee propolis is a natural substance that is used in traditional medicine due to its versatile pharmacological actions. This study evaluates whether short term use of bee propolis supplementation could have an impact on glycemic control in healthy individuals.

Materials and Methods

A single daily dose of 1000 mg of bee propolis was administered orally to a total of 34 healthy individuals for 60 days. Body weight, body mass index (BMI), fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), and insulin resistance were measured in all participants before and after the use of bee propolis.

Results

The results of this study showed that bee propolis was associated with a significant increase in body weight and BMI of healthy volunteers. Bee propolis supplementation decreased FBG and HbA1c, but did not affect insulin resistance.

Conclusion

Based on these results, bee propolis supplementation has a potential effect on glycemic control in healthy individuals and this should be considered when using this supplement in medical conditions.

Nonaqueous Polyethylene Glycol as a Safer Alternative to Ethanolic Propolis Extracts with Comparable Antioxidant and Antimicrobial Activity

We compared the chemical composition, antioxidant and antimicrobial activity of two propolis extracts: one obtained with nonaqueous polyethylene glycol, PEG 400 (PgEP), and the other obtained with ethanol (EEP). We analyzed the total phenolic content (TPC) and the concentrations of ten markers of propolis antioxidant activity with HPLC-UV: caffeic acid, p-coumaric acid, trans-ferulic acid, trans-cinnamic acid, kaempferol, apigenin, pinocembrin, chrysin, CAPE, and galangin. Antioxidant activity was tested using DPPH and FRAP assay, and antimicrobial activity was assessed through minimum inhibitory concentrations (MICs) and minimum biofilm eradication concentration (MBEC) determination. Maceration gave the yield of propolis of 25.2 ± 0.08% in EEP, and 21.5 ± 0.24% in PgEP. All ten markers of antioxidant activity were found in both extracts, with all marker concentrations, except kaempferol, higher in EEP. There was no significant difference between the TPC and antioxidant activity of the PgEP and the EEP extract; TPC of PgEP was 16.78 ± 0.23 mg/mL, while EEP had TPC of 15.92 ± 0.78 mg/mL. Both extracts had antimicrobial activity against most investigated pathogens and Staphylococcus aureus, Acinetobacter baumannii, and Escherichia coli biofilms. EEP was more effective against all tested susceptible pathogens, except E. coli, possibly due to higher content of kaempferol in PgEP relative to other polyphenols. Nonaqueous PEG 400 could be used for propolis extraction. It gives extracts with comparable concentrations of antioxidants and has a good antioxidant and antimicrobial activity. It is a safe excipient, convenient for pediatric and veterinary formulations.

Propolis Extract and Its Bioactive Compounds-From Traditional to Modern Extraction Technologies

Propolis is a honeybee product known for its antioxidant, anti-inflammatory, anticancer, and antimicrobial effects. It is rich in bioactive molecules whose content varies depending on the botanical and geographical origin of propolis. These bioactive molecules have been studied individually and as a part of propolis extracts, as they can be used as representative markers for propolis standardization. Here, we compare the pharmacological effects of representative polyphenols and whole propolis extracts. Based on the literature data, polyphenols and extracts act by suppressing similar targets, from pro-inflammatory TNF/NF-κB to the pro-proliferative MAPK/ERK pathway. In addition, they activate similar antioxidant mechanisms of action, like Nrf2-ARE intracellular antioxidant pathway, and they all have antimicrobial activity. These similarities do not imply that we should attribute the action of propolis solely to the most representative compounds. Moreover, its pharmacological effects will depend on the efficacy of these compounds’ extraction. Thus, we also give an overview of different propolis extraction technologies, from traditional to modern ones, which are environmentally friendlier. These technologies belong to an open research area that needs further effective solutions in terms of well-standardized liquid and solid extracts, which would be reliable in their pharmacological effects, environmentally friendly, and sustainable for production.

Inhibitory potential on key enzymes relevant to type II diabetes mellitus and antioxidant properties of the various extracts and phytochemical constituents from Rumex acetosella L

Type II diabetes mellitus is a common and costly disease worldwide, characterized by hyperglycemia. Alpha (α)-amylase and α-glucosidase are important targets in diabetes therapy. Inhibition of these enzymes may lessen hyperglycemia, preventing diabetic complications. Oxidative stress is another factor involved in the disease's etiology. In the present study, we investigated antidiabetic profiles of the various extracts and phytochemicals of Rumex acetosella. Since the plant has been traditionally used for the antidiabetic purposes. α-amylase and α-glucosidase inhibitory studies in addition to DPPH•, ABTS•+, NO 2 - radical scavenging, and phosphomolybdate antioxidant assays were performed to evaluate the antidiabetic property. Specifically, the ethanol and ethanol-water extracts remarkably inhibited α-glucosidase than that of acarbose, unlike their slight/no inhibition on α-amylase. Convincing α-glucosidase inhibitory and antioxidant potential of alcohol-including extracts verified the ethnobotanical use of R. acetosella as an antidiabetic agent. PRACTICAL APPLICATIONS: The incidence of Type II DM is rising globally. Reducing hyperglycemia holds great importance to prevent devastating outcomes of diabetic complications. Ethnobotanical use of natural sources for medical purposes provides a basis for their potential activity against various diseases. The introduction of herbal agents may lead to the development of new drug candidates with convincing activity. Rumex acetosella L. has been traditionally used for the antidiabetic purposes. The research pointed out various extracts and phytochemical constituents from R. acetosella may act as antihyperglycemic agents. Particularly, alcohol-including extracts of R. acetosella may be considered as promising alternatives in the prevention or treatment of type II DM. The study puts emphasis on the therapeutic value of the plants for antidiabetic medication.

Iranian brown propolis possesses neuroprotective effect against ischemic neuronal damage in mice

Introduction: Stroke is one of the leading causes of death and disability worldwide. Propolis, a polyphenol-rich resinous product processed by honeybees from a variety of plant sources, has a set of biological activities. We investigated the neuroprotective effect of Iranian brown propolis (IBP) in a mouse model of permanent middle cerebral artery occlusion (MCAO). Methods: Experimentally, water extracts of propolis (WEPs) were obtained from Kerman (KeWEP) and Khorasan Razavi (KhWEP) provinces, Iran. The chemical characterization and total polyphenol content of WEPs were determined using the Folin–Ciocalteu assay and gas chromatography-mass spectrometry (GC-MS). Animals were divided into eight experimental groups including: sham, control, and three groups each of which KeWEP- and KhWEP-treated mice. The drugs were administered at doses of 30, 100 and 200 mg/kg, intraperitoneally (IP), during four different time points. Infarct volume and brain edema were measured at 48 h. Behavioral tests were evaluated at 4, 24 and 48-hour post stroke. Results: The total polyphenol content was 1100 and 1400 mg/L in KhWEP and KeWEP respectively. Compared to the control group, the doses of 100 and 200 mg/kg in both samples decreased infarct volume. Brain edema was also reduced in all treatment groups. The dose of 200 mg/kg in both samples and 100 mg/kg in the KeWEP-treated group significantly increased grasping ability. Sensory-motor function was improved in all groups, too. Conclusion: These results suggest that IBP may reduce ischemic brain injury by its neuroprotective effect on focal cerebral ischemia.

Neuroprotective effects of Brazilian green propolis on oxytosis/ferroptosis in mouse hippocampal HT22 cells

Propolis is a sticky dark-colored substance produced by honey bees and comprises resin, balsam, wax, essential and aromatic oils, pollen, and several other substances; it is used in food and beverages to improve health and prevent diseases. We studied the neuroprotective effects of extracts of Brazilian green propolis in the mouse hippocampal cell line HT22. Ethanol extracts of Brazilian green propolis had a more potent preventive effect on oxidative stress-induced cell death, oxytosis/ferroptosis, in HT22 cells than water extracts of Brazilian green propolis, whereas it did not protect against anticancer drug-induced apoptotic cell death. Among the primary constituents of ethanol extracts of Brazilian green propolis, only artepillin C, kaempferide, and kaempferol demonstrated neuroprotective effects against oxytosis/ferroptosis. The flavonoid derivatives kaempferide and kaempferol are antioxidants with radical-scavenging abilities that additionally induce antioxidant response element-mediated transcriptional activity, suggesting that upregulation of endogenous antioxidant defense protects against oxidative stress. In contrast, artepillin C attenuated reactive oxygen species production; however, it did not induce antioxidant response element activation. These findings indicate that the ethanol extracts of Brazilian green propolis help to prevent oxidative stress-related neuronal cell death that is involved in the pathogenesis of several neurodegenerative diseases.

Brazilian Green Propolis Inhibits Ox-LDL-Stimulated Oxidative Stress in Human Umbilical Vein Endothelial Cells Partly through PI3K/Akt/mTOR-Mediated Nrf2/HO-1 Pathway

Propolis has been widely used as a dietary supplement for its health benefits, including cardiovascular protective effects. The aim of this study was to investigate the cytoprotective effects of Brazilian green propolis (BP) against oxidized low-density lipoprotein (Ox-LDL) induced human umbilical vein endothelial cells (HUVECs) damage. Our results suggested that treatment with BP rescued Ox-LDL-stimulated HUVECs cell viability losses, which might be associated with its inhibitive effects on the cell apoptosis and autophagy. We also noticed that BP restored Ox-LDL-stimulated HUVECs oxidative stress, by induced antioxidant gene expressions, including Heme oxygenase-1 and its upstream mediator, Nrf2, which were mediated by the activation of the phosphorylation of PI3K/Akt/mTOR. Pretreatment with wortmannin, PI3K/AKT inhibitor, abolished BP induced Nrf2 nuclear translocation and HO-1 level. Our results demonstrated that BP protected HUVECs against oxidative damage partly via PI3K/Akt/mTOR-mediated Nrf/HO-1 pathway, which might be applied into preventing Ox-LDL mediated cardiovascular diseases.

The Effect of Iranian Propolis on Glucose Metabolism, Lipid Profile, Insulin Resistance, Renal Function and Inflammatory Biomarkers in Patients with Type 2 Diabetes Mellitus: A Randomized Double-Blind Clinical Trial

Propolis is a natural product with many biological properties including hypoglycemic activity and modulating lipid profile. The present study was designed to evaluate the effect of Iranian propolis extract on glucose metabolism, Lipid profile, Insulin resistance, renal and liver function as well as inflammatory biomarkers in patients with type 2 diabetes mellitus (T2DM). A double-blind, placebo-controlled clinical trial was conducted. The duration of the study lasted 90 days. Patients with T2DM were recruited and randomly divided into an Iranian propolis group (1000 mg/day) (n = 50) and a placebo group (n = 44). There was a significant decrease in the serum levels of glycosylated hemoglobin (HbA1c), 2-hour post prandial (2hpp), insulin, homeostasis model assessment-insulin resistance (HOMA-IR), homeostasis model assessment of β-cell function (HOMA-β), High sensitive C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α). However, there was a notable elevation in the serum HDL-C in the propolis group compared with the placebo group. In addition, a notable reduction in serum liver transaminase (ALT and AST) and blood urea nitrogen (BUN) concentrations in the propolis group was observed. Iranian propolis has beneficial effects on reducing post prandial blood glucose, serum insulin, insulin resistance, and inflammatory cytokines. It is also a useful treatment for preventing the liver and renal dysfunction, as well as, elevating HDL-C concentrations in patients with T2DM.

Propolis Extracts Inhibit UV-Induced Photodamage in Human Experimental In Vitro Skin Models

The aim of this study was to assess the antioxidant, photoprotective, and antiaging effects of Greek propolis. Propolis was subjected to n-heptane or methanol extraction. Total phenolic/flavonoid content and antioxidant potential were determined in the extracts. Promising extracts were evaluated for their cytoprotective properties using human immortalized keratinocyte (HaCaT) or reconstituted human skin tissue following exposure to UVB. Assessment of cytotoxicity, DNA damage, oxidative status, and gene/protein expression levels of various matrix metalloproteinases (MMPs) were performed. The propolis methanolic fractions exhibited higher total phenolic and flavonoid contents and significant in vitro antioxidant activity. Incubation of HaCaT cells with certain methanolic extracts significantly decreased the formation of DNA strand breaks following exposure to UVB and attenuated UVB-induced decrease in cell viability. The extracts had no remarkable effect on the total antioxidant status, but significantly lowered total protein carbonyl content used as a marker for protein oxidation in HaCaT cells. MMP-1, -3, -7, and -9, monitored as endpoints of antiaging efficacy, were significantly reduced by propolis following UVB exposure in a model of reconstituted skin tissue. In conclusion, propolis protects against the oxidative and photodamaging effects of UVB and could be further explored as a promising agent for developing natural antiaging strategies.

Potential Antinociceptive Effects of Chinese Propolis and Identification on Its Active Compounds

Propolis is an important bee product which has been applied to the treatment of several diseases. The aim of this study was to understand the material basis of Chinese propolis on pain relief; different Chinese propolis fractions (40W, 40E, 70E, and 95E raw propolis extracted followed by 40%, 70%, or 95% ethanol) were prepared, and their antinociceptive effects were evaluated. By analyzing using UPLC-Q-TOF-MS, we showed that 40W was rich in phenolic acids, like caffeic acid, while 40E, 70E, and 95E have relatively high levels in flavonoids, like galangin, pinocembrin, and chrysin. Notably, chrysin amounts in 70E and 95E are much higher than those in 40E fraction. Antinociceptive effects by these propolis fractions were evaluated in mice using acetic acid-induced writhing test, hot plate test, and tail immersion test, respectively. We noticed that only 40E fraction showed a significant reduction on acetic acid-induced writhing test. Importantly, in the hot plate test, all groups showed their effectiveness, except for the 70E group. We also noticed that 40W, 40E, and 95E administration caused an increase in the tail withdrawal latency of the mice. These data suggested that the different antinociceptive effects of different fractions from Chinese propolis extracts are directly link to their flavonoid composition.

Brazilian green propolis suppresses acetaminophen-induced hepatocellular necrosis by modulating inflammation-related factors in rats

Propolis is a resin-like material produced by honey bees from bud exudates and sap of plants and their own secretions. An ethanol extract of Brazilian green propolis (EEBGP) contains prenylated phenylpropanoids and flavonoids and has antioxidative and anti-inflammatory effects. Acetaminophen (N-acetyl-p-aminophenol; APAP) is a typical hepatotoxic drug, and APAP-treated rats are widely used as a model of drug-induced liver injury. Oxidative stress and inflammatory reactions cause APAP-induced hepatocellular necrosis and are also related to expansion of the lesion. In the present study, we investigated the preventive effects of EEBGP on APAP-induced hepatocellular necrosis in rats and the protective mechanism including the expression of antioxidative enzyme genes and inflammation-related genes. A histological analysis revealed that administration 0.3% EEBGP in the diet for seven days reduced centrilobular hepatocellular necrosis with inflammatory cell infiltration induced by oral administration of APAP (800 mg/kg) and significantly reduced the area of necrosis. EEBGP administration did not significantly change the mRNA expression levels of antioxidant enzyme genes in the liver of APAP-treated rats but decreased the mRNA expression of cytokines including Il10 and Il1b, with a significant difference in Il10 expression. In addition, the decrease in the mRNA levels of the Il1b and Il10 genes significantly correlated with the decrease in the percentage of hepatocellular necrosis. These findings suggest that EEBGP could suppress APAP-induced hepatocellular necrosis by modulating cytokine expression.

Inhibitory effect of propolis on the development of AA amyloidosis

In the several types of amyloidoses, participation of oxidative stresses in the pathogenesis and the effect of antioxidants on amyloidosis have been reported. Meanwhile, the relationship between oxidative stresses and pathogenesis of amyloid A (AA) amyloidosis is still unclear. In this study, we used an antioxidant, Brazilian propolis, to investigate the inhibitory effects on AA amyloidosis. The results showed that AA deposition was inhibited by administration of propolis. Increased expression of antioxidant markers was detected in molecular biological examinations of mice treated with propolis. Although serum amyloid A (SAA) levels were strongly correlated with the immunoreactive area of AA deposits in the control group, the correlation was weaker in the propolis-treated groups. In addition, there were no changes in SAA levels between the control group and the propolis-treated groups. The results indicate that propolis, an antioxidant, may induce inhibitory effects against AA amyloidosis.

Effect of Green and Brown Propolis Extracts on the Expression Levels of microRNAs, mRNAs and Proteins, Related to Oxidative Stress and Inflammation

A large body of evidence highlights that propolis exerts many biological functions that can be ascribed to its antioxidant and anti-inflammatory components, including different polyphenol classes. Nevertheless, the molecular mechanisms are yet unknown. The aim of this study is to investigate the mechanisms at the basis of propolis anti-inflammatory and antioxidant activities. The effects of two brown and green propolis extracts-chemically characterized by RP-HPLC-PDA-ESI-MSn-on the expression levels of miRNAs associated with inflammatory responses (miR-19a-3p and miR-203a-3p) and oxidative stress (miR-27a-3p and miR-17-3p), were determined in human keratinocyte HaCat cell lines, treated with non-cytotoxic concentrations. The results showed that brown propolis, whose major polyphenolic components are flavonoids, induced changes in the expression levels of all miRNAs, and was more active than green propolis (whose main polyphenolic components are hydroxycinnamic acid derivatives) which caused changes only in the expression levels of miR-19a-3p and miR-27a-3p. In addition, only brown propolis was able to modify (1) the expression levels of mRNAs, the target of the reported miRNAs, which code for Tumor Necrosis Factor-α (TNF-α), Nuclear Factor, Erythroid 2 Like 2 (NFE2L2) and Glutathione Peroxidase 2 (GPX2), and (2) the protein levels of TNF-α and NFE2L2. In conclusion, brown and green propolis, which showed different metabolite profiles, exert their biological functions through different mechanisms of action.