Brazilian Green Propolis Prevents Cognitive Decline into Mild Cognitive Impairment in Elderly People Living at High Altitude

Effects of Propolis Consumption on Liver Enzymes and Obesity Indices in Adults: A Systematic Review and Dose-Response Meta-Analysis

Background

Propolis, a natural resin produced by bees, has been studied for its potential effects on liver enzymes and obesity indices. However, a meta-analysis is necessary to comprehensively understand the impact of propolis on obesity and liver function.

Objectives

This meta-analysis of randomized controlled trials (RCTs) sought to evaluate the effects of propolis consumption on liver enzymes and obesity indices in adults.

Methods

A systematic literature search up to December 2023 was completed in PubMed/Medline, Scopus, and Web of Science, to identify eligible RCTs. Heterogeneity tests of the selected trials were performed using the I 2 statistic. Random-effects models were assessed on the basis of the heterogeneity tests, and pooled data were determined as weighted mean differences (WMDs) with a 95% confidence interval (CI).

Results

A pooled analysis of 24 trials showed that propolis consumption led to a significant reduction in alanine aminotransferase (ALT) (WMD: -2.58; 95% CI: -4.64, -0.52; P = 0.01), aspartate aminotransferase (AST) (WMD: -1.84; 95% CI: -3.01, -0.67; P = 0.002), and alkaline phosphatase (ALP) (WMD: -24.90; 95% CI: -42.13, -7.67; P = 0.005) in comparison with the control group. However, there were no significant effects on gamma-glutamyl transferase (GGT), body weight, BMI (in kg/m2), fat mass, body fat percentage, fat-free mass, adiponectin, waist circumference, hip circumference, and waist-hip ratio in comparison with the control group.

Conclusions

We discovered that consuming propolis can lead to a significant decrease in ALT, AST, and ALP levels, without causing significant changes in GGT, anthropometric indices, and adiponectin levels. However, future well-designed RCTs with large numbers of participants and extended durations, focusing on precise propolis dosage and ingredients, are necessary.

Effects of Propolis Consumption on Glycemic Indices and Liver Enzymes in Adults: A Grading of Recommendations Assessment, Development, and Valuation-assessed Systematic Review and Dose-Response Meta-analysis

PURPOSE

Even though various randomized controlled trials (RCTs) have assessed the effect of propolis on glycemic indices and liver enzyme concentrations in adults, results have been inconsistent, without conclusive evidence. This systematic review and meta-analysis of RCTs sought to evaluate the effects of propolis consumption on glycemic indices and liver enzymes, fasting blood glucose, insulin, homeostatic model assessment of insulin resistance, glycosylated hemoglobin, alanine transaminase, aspartate aminotransferase, and gamma-glutamyl transferase in adults.

METHODS

Two independent researchers systematically searched PubMed, EMBASE, Scopus, Web of Science, and the Cochrane Library for English-language RCTs published up to April 2024. The results were generated through a random-effects model and presented as the weighted mean difference (WMD) with a 95% CI. The Cochrane Risk of Bias Tool for RCTs and Grading of Recommendations Assessment, Development, and Evaluation assessment were used to evaluate quality assessment and certainty of evidence.

FINDINGS

A total of 21 RCTs were included. A pooled analysis of 24 trials reported that propolis consumption led to a significant reduction in fasting blood glucose (WMD, -9.75 mg/dL; 95% CI, -16.14 to -3.35), insulin (WMD, -1.64 µU/mL; 95% CI, -2.61 to -0.68), glycosylated hemoglobin (WMD, -0.46%; 95% CI, -0.71 to -0.21), homeostatic model assessment of insulin resistance (WMD, -0.54; 95% CI, -0.98 to -0.09), alanine transaminase (WMD, -2.60 IU/L; 95% CI, -4.58 to -0.61), and aspartate aminotransferase (WMD, -2.07 IU/L; 95% CI, -3.05 to -1.09). However, there were no significant effects on gamma-glutamyl transferase in comparison with the control group.

IMPLICATIONS

This meta-analysis has shown that propolis supplementation may have beneficial effects on glycemic indices and liver enzymes. Future high-quality, long-term RCTs are needed to confirm our results.

CLINICALTRIALS

gov identifiers: CRD42024524763. (Clin Ther. 2024;46:XXX-XXX) © 2024 Elsevier HS Journals, Inc.

Propolis supplementation can reduce serum level of interleukin-6, C-reactive protein, and tumor necrosis factor-α: an updated systematic review and dose-response meta-analysis on randomized clinical trials

BACKGROUND

New evidence suggested that propolis might reduce serum levels of inflammatory mediators; therefore, in this study we aimed to prove the potential effect of propolis on serum levels of interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-α) through conducting a systematic review and meta-analysis.

METHODS

Databases including PubMed, ClinicalTrials.gov, Scopus, Cochrane Library, and ISI Web of Science were searched until October 2023. In the present meta-analysis, we detected the overall effect sizes using extracted standard mean differences (SMD) and the standard deviations (SDs) from both study groups through DerSimonian and Laird method. Exploring the statistical heterogeneity was done through Cochran's Q test and I-squared statistic.

RESULTS

In total, seventeen and sixteen studies were included in the systematic review and meta-analysis, respectively. The overall estimate indicated that the propolis significantly reduced serum levels of IL-6 (SMD = -3.47, 95% confidence interval (95%CI): -5.1, -1.84; p < 0.001), CRP (SMD= -1.73, 95%CI: -2.82, -0.65; p = 0.002), and TNF-α (SMD= -1.42, 95%CI= -2.15, -0.68; p < 0.001). These results also revealed geographical region and propolis dose were the critical points to get the beneficial effects.

CONCLUSION

According to our result, propolis supplementation can decrease serum levels of IL-6, CRP, and TNF-α; therefore, it might be considered as complementary therapy for the treatment of certain chronic diseases.

Preventive effect of propolis on cognitive decline in Alzheimer's disease model mice

Brazilian green propolis (propolis) is a chemically complex resinous substance that is a potentially viable therapeutic agent for Alzheimer's disease. Herein, propolis induced a transient increase in intracellular Ca2+ concentration ([Ca2+]i) in Neuro-2A cells; moreover, propolis-induced [Ca2+]i elevations were suppressed prior to 24-h pretreatment with amyloid-β. To reveal the effect of [Ca2+]i elevation on impaired cognition, we performed memory-related behavioral tasks in APP-KI mice relative to WT mice at 4 and 12 months of age. Propolis, at 300-1000 mg/kg/d for 8 wk, significantly ameliorated cognitive deficits in APP-KI mice at 4 months, but not at 12 months of age. Consistent with behavioral observations, injured hippocampal long-term potentiation was markedly ameliorated in APP-KI mice at 4 months of age following repeated propolis administration. In addition, repeated administration of propolis significantly activated intracellular calcium signaling pathway in the CA1 region of APP-KI mice. These results suggest a preventive effect of propolis on cognitive decline through the activation of intracellular calcium signaling pathways in CA1 region of AD mice model.

Chemical Composition and Neuroprotective Properties of Indonesian Stingless Bee (Geniotrigona thoracica) Propolis Extract in an In-Vivo Model of Intracerebral Hemorrhage (ICH)

Stroke is the world's second-leading cause of death. Current treatments for cerebral edema following intracerebral hemorrhage (ICH) mainly involve hyperosmolar fluids, but this approach is often inadequate. Propolis, known for its various beneficial properties, especially antioxidant and anti-inflammatory properties, could potentially act as an adjunctive therapy and help alleviate stroke-associated injuries. The chemical composition of Geniotrigona thoracica propolis extract was analyzed by GC-MS after derivatization for its total phenolic and total flavonoid content. The total phenolic content and total flavonoid content of the propolis extract were 1037.31 ± 24.10 μg GAE/mL and 374.02 ± 3.36 μg QE/mL, respectively. By GC-MS analysis, its major constituents were found to be triterpenoids (22.4% of TIC). Minor compounds, such as phenolic lipids (6.7% of TIC, GC-MS) and diterpenic acids (2.3% of TIC, GC-MS), were also found. Ninety-six Sprague Dawley rats were divided into six groups; namely, the control group, the ICH group, and four ICH groups that received the following therapies: mannitol, propolis extract (daily oral propolis administration after the ICH induction), propolis-M (propolis and mannitol), and propolis-B+A (daily oral propolis administration 7 days prior to and 72 h after the ICH induction). Neurocognitive functions of the rats were analyzed using the rotarod challenge and Morris water maze. In addition, the expression of NF-κB, SUR1-TRPM4, MMP-9, and Aquaporin-4 was analyzed using immunohistochemical methods. A TUNEL assay was used to assess the percentage of apoptotic cells. Mannitol significantly improved cognitive-motor functions in the ICH group, evidenced by improved rotarod and Morris water maze completion times, and lowered SUR-1 and Aquaporin-4 levels. It also significantly decreased cerebral edema by day 3. Similarly, propolis treatments (propolis-A and propolis-B+A) showed comparable improvements in these tests and reduced edema. Moreover, combining propolis with mannitol (propolis-M) further enhanced these effects, particularly in reducing edema and the Virchow-Robin space. These findings highlight the potential of propolis from the Indonesian stingless bee, Geniotrigona thoracica, from the Central Tapanuli region as a neuroprotective, adjunctive therapy.

Exploring the Prospective Role of Propolis in Modifying Aging Hallmarks

Aging populations worldwide are placing age-related diseases at the forefront of the research agenda. The therapeutic potential of natural substances, especially propolis and its components, has led to these products being promising agents for alleviating several cellular and molecular-level changes associated with age-related diseases. With this in mind, scientists have introduced a contextual framework to guide future aging research, called the hallmarks of aging. This framework encompasses various mechanisms including genomic instability, epigenetic changes, mitochondrial dysfunction, inflammation, impaired nutrient sensing, and altered intercellular communication. Propolis, with its rich array of bioactive compounds, functions as a potent functional food, modulating metabolism, gut microbiota, inflammation, and immune response, offering significant health benefits. Studies emphasize propolis' properties, such as antitumor, cardioprotective, and neuroprotective effects, as well as its ability to mitigate inflammation, oxidative stress, DNA damage, and pathogenic gut bacteria growth. This article underscores current scientific evidence supporting propolis' role in controlling molecular and cellular characteristics linked to aging and its hallmarks, hypothesizing its potential in geroscience research. The aim is to discover novel therapeutic strategies to improve health and quality of life in older individuals, addressing existing deficits and perspectives in this research area.

Brazilian green propolis prevent Alzheimer's disease-like cognitive impairment induced by amyloid beta in mice

BACKGROUND

The increasing incidence of cognitive impairment has become a health problem in the aging society. Owing to its antioxidant and anti-inflammatory properties, Brazilian green propolis-derived from Baccharis dracunculifolia-is anticipated to possess anticognitive properties. However, the preventive effect of Brazilian green propolis on cognitive impairment remains unexplained. This study aimed to investigate the effect of Brazilian green propolis on cognitive impairment using a mouse model of Alzheimer's disease (AD) induced by intracerebroventricular injection of amyloid beta (Aβ)25‒35.

METHODS

Five-week-old male Slc:ddY mice were randomly divided into five groups (n = 8). The groups were pretreated with vehicle and propolis at a dose of 100, 300 and 900 mg/kg body weight for 8 days, then AD-like phenotypes were induced by intracerebroventricular (ICV) injection of Aβ25‒35. A sham operation group was set as the control. Memory and learning ability were measured at 7 to 8 days after ICV injection. Gene expression and histological studies were performed at the endpoint of the study.

RESULTS

In a passive avoidance test, the administration of Brazilian green propolis prevented the impairment of learning and memory function. Furthermore, comprehensive gene expression analysis in the hippocampus and forebrain cortex revealed that Brazilian green propolis suppressed Aβ25-35-induced inflammatory and immune responses. In particular, Brazilian green propolis prevented alterations in gene expressions of microglial and astrocytic markers such as Trem2 and Lcn2 induced by Aβ25‒35 injection, suggesting the suppression of excessive activation of glial cells in the brain. In addition, Brazilian green propolis suppressed the elevation of plasma interleukin (IL)-6 levels induced by Aβ25‒35 injection.

CONCLUSIONS

The results suggest that the prophylactic administration of Brazilian green propolis has a preventive effect against AD by suppressing excessive inflammation and immune response in glial cells. To our knowledge, this study is the first to demonstrate that Brazilian green propolis may inhibit the hyperactivation of microglia and astrocytes as a mechanism of action to prevent AD. Thus, it is a promising ingredient for preventing AD-type dementia.

Propolis as a Potential Therapeutic Agent to Counteract Age-Related Changes in Cartilage: An In Vivo Study

Aging is intricately linked to chronic low-grade systemic inflammation, which plays a significant role in various age-related conditions, including osteoarthritis (OA). The aging process significantly influences the development of OA due to alterations in cartilage composition, reduced proteoglycan content, dysregulation of growth factor signaling, and heightened oxidative stress. Propolis, a natural product renowned for its potent antioxidant and anti-inflammatory properties, has the potential to mitigate age-induced changes in cartilage. The primary objective of this study was to rigorously assess the impact of in vivo propolis treatment on the histopathological characteristics of knee articular cartilage in senescent rats. This study involved a cohort of twenty male Sprague-Dawley rats, randomly allocated into four distinct groups for comparative analysis: YR (control group consisting of young rats), SR (senescent rats), SR-EEP (senescent rats treated with an ethanolic extract of propolis, EEP), and SR-V (senescent rats administered with a control vehicle). This study employed comprehensive histological and stereological analyses of knee articular cartilage. Propolis treatment exhibited a significant capacity to alleviate the severity of osteoarthritis, enhance the structural integrity of cartilage, and augment chondrocyte density. These promising findings underscore the potential of propolis as a compelling therapeutic agent to counteract age-related alterations in cartilage and, importantly, to potentially forestall the onset of osteoarthritis.

Mechanism, prevention and treatment of cognitive impairment caused by high altitude exposure

Hypobaric hypoxia (HH) characteristics induce impaired cognitive function, reduced concentration, and memory. In recent years, an increasing number of people have migrated to high-altitude areas for work and study. Headache, sleep disturbance, and cognitive impairment from HH, severely challenges the physical and mental health and affects their quality of life and work efficiency. This review summarizes the manifestations, mechanisms, and preventive and therapeutic methods of HH environment affecting cognitive function and provides theoretical references for exploring and treating high altitude-induced cognitive impairment.

Poplar Propolis Improves Insulin Homeostasis in Non-Diabetic Insulin-Resistant Volunteers with Obesity: A Crossover Randomized Controlled Trial

Propolis, a natural resinous mixture rich in polyphenols, produced by bees from a variety of plant sources, has shown significant therapeutic effects and may prevent the development of certain chronic diseases like type 2 diabetes mellitus (T2DM). The objective of this study was to evaluate the effect of supplementation with standardized poplar propolis extract powder (PPEP) on insulin homeostasis in non-diabetic insulin-resistant volunteers with obesity. In this randomized, controlled, crossover trial, nine non-diabetic insulin-resistant volunteers with obesity, aged 49 ± 7 years, were subjected to two periods of supplementation (placebo and PPEP) for 3 months. Blood samples and anthropomorphic data were collected at baseline and at the end of each phase of the intervention. PPEP supplementation improved insulin sensitivity by significantly decreasing the percentage of insulin-resistant subjects and the insulin sensitivity Matsuda index (ISI-M). According to this study, supplementation with standardized PPEP for 3 months in non-diabetic insulin-resistant volunteers with obesity led to an improvement in insulin homeostasis by its effect on insulin resistance and secretion. This study suggests that poplar propolis has a preventive effect on the physiopathological mechanisms of T2DM and, therefore, that it can help to prevent the development of the disease.

Brazilian Propolis Intake Decreases Body Fat Mass and Oxidative Stress in Community-Dwelling Elderly Females: A Randomized Placebo-Controlled Trial

This study aimed to investigate the effects of Brazilian propolis on body fat mass and levels of adiponectin and reactive oxygen species among community-dwelling elderly females. This was a double-blind randomized placebo-controlled trial. Altogether, 78 females aged 66-84 years were randomly assigned to the propolis (PRO; n = 39) or placebo (PLA; n = 39) group. For 12 weeks, the PRO group were given three capsules containing 227 mg of propolis twice a day. Meanwhile, the PLA group were given daily placebo capsules. Of 78 participants, 53 (PLA group: n = 28, PRO group: n = 25) completed the study. Although no changes were observed in absolute or relative fat mass in the PLA group, they showed a significant decline in the PRO group. The level of serum adiponectin in the PLA group did not change, although that of the PRO group significantly increased. The level of d-ROMs in the PLA group significantly increased, whereas that of the PRO group significantly decreased. The serum SOD activity in the PLA group significantly decreased, whereas that of the PRO group tended to increase. These results suggest that propolis supplementation may decrease body fat mass and oxidative stress among community-dwelling elderly females.

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

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

Recent Update on the Anti-Inflammatory Activities of Propolis

In recent years, research has demonstrated the efficacy propolis as a potential raw material for pharmaceuticals and nutraceuticals. There is limited report detailing the mechanisms of action of propolis and its bioactive compounds in relation to their anti-inflammatory properties. Thus, the aim of the present review is to examine the latest experimental evidence (2017-2022) regarding the anti-inflammatory properties of propolis. A systematic scoping review methodology was implemented. After applying the exclusion criteria, a total of 166 research publications were identified and retrieved from Scopus, Web of Science, and Pubmed. Several key themes related to the anti-inflammatory properties of propolis were subsequently identified, namely in relation to cancers, oral health, metabolic syndrome, organ toxicity and inflammation, immune system, wound healing, and pathogenic infections. Based on the latest experimental evidence, propolis is demonstrated to possess various mechanisms of action in modulating inflammation towards the regulatory balance and anti-inflammatory environment. In general, we summarize that propolis acts as an anti-inflammatory substance by inhibiting and downregulating TLR4, MyD88, IRAK4, TRIF, NLRP inflammasomes, NF-κB, and their associated pro-inflammatory cytokines such as IL-1β, IL-6, IFN-γ, and TNF-α. Propolis also reduces the migration of immune cells such as macrophages and neutrophils, possibly by downregulating the chemokines CXCL9 and CXCL10.

The gut microbiota in neurodegenerative diseases: revisiting possible therapeutic targets for cannabidiol

Understanding the pathophysiology of Alzheimer's disease (AD) is essential to improve the efficacy of treatments and, consequently, patients' lives. Unfortunately, traditional therapeutic strategies have not been effective. There is therefore an urgent need to discover or develop alternative treatment strategies. Recently, some pieces of the puzzle appear to emerge: on a hand, the gut microbiota (GM) has gained attention since intestinal dysbiosis aggravates and generates some of the pathological processes of AD; on the other hand, cannabidiol (CBD), a phytocannabinoid, attenuates intestinal inflammation and possesses neuroprotective properties. Intestinal dysbiosis (increased population of proinflammatory bacteria) in AD increases plasma lipopolysaccharide and Aβ peptide levels, both responsible for increasing the permeability of the blood-brain barrier (BBB). A leaky BBB may facilitate the entry of peripheral inflammatory mediators into the central nervous system and ultimately aggravate neuroinflammation and neuronal death due to chronic activation of glial cells. Studies investigating the GM reported a strong relationship between intestinal dysbiosis and AD. In this review we conjecture that the GM is a promising therapeutic target for CBD in the context of AD.

Polyphenols-Based Nanosheets of Propolis Modulate Cytotoxic Amyloid Fibril Assembly of α-Synuclein

Natural compounds with anti-aggregation capacity are increasingly recognized as viable candidates against neurodegenerative diseases. Recently, the polyphenolic fraction of propolis (PFP), a complex bee product, has been shown to inhibit amyloid aggregation of a model protein especially in the nanosheet form. Here, we examine the aggregation-modulating effects of the PFP nanosheets on α-synuclein (α-syn), an intrinsically disordered protein involved in the pathogenesis of Parkinson's disease. Based on a range of biophysical data including intrinsic and extrinsic fluorescence, circular dichroism (CD) data, and nuclear magnetic resonance spectroscopy, we propose a model for the interaction of α-syn with PFP nanosheets, where the positively charged N-terminal and the middle non-amyloid component regions of α-syn act as the main binding sites with the negatively charged PFP nanosheets. The Thioflavin T (ThT) fluorescence, Congo red absorbance, and CD data reveal a prominent dose-dependent inhibitory effect of PFP nanosheets on α-syn amyloid aggregation, and the microscopy images and MTT assay data suggest that the PFP nanosheets redirect α-syn aggregation toward nontoxic off-pathway oligomers. When preformed α-syn amyloid fibrils are present, fluorescence images show co-localization of PFP nanosheets and ThT, further confirming the binding of PFP nanosheets with α-syn amyloid fibrils. Taken together, our results demonstrate the binding and anti-aggregation activity of PFP nanosheets in a disease-related protein system and propose them as potential nature-based tools for probing and targeting pathological protein aggregates in neurodegenerative diseases.

Does propolis have any effect on rheumatoid arthritis? A review study

Rheumatoid arthritis (RA) is a chronic autoimmune disease in which inflammation and oxidative stress play a key role in its pathophysiology. Complementary therapies along with medications may be effective in the control of RA. Propolis is a natural substance extracted from beehives, which have confirmed anti-inflammatory and antioxidant effects. The present study aimed to review the possible effects of propolis on inflammation, oxidative stress, and lipid profile in patients with RA. English articles in online databases such as PubMed‑Medline, AMED, Google Scholar, EMBASE, Scopus, and Web of Science databases were searched. Pieces of evidence show that supplementation with propolis may have therapeutic effects on RA patients. Due to increased inflammation and oxidative stress in the affected joints of RA patients, propolis could inhibit the inflammatory cascades by inhibiting the nuclear factor kappa B pathway and reducing reactive oxygen species, malondialdehyde, and interleukin-17 by increasing some antioxidants. Therefore, inflammation and pain reduce, helping improve and control RA in patients. Further investigations are required with larger sample sizes and different doses of propolis to demonstrate the definite effects of propolis on various aspects of RA.

Unusual Bioactive Compounds with Antioxidant Properties in Adjuvant Therapy Supporting Cognition Impairment in Age-Related Neurodegenerative Disorders

Cognitive function decline is strictly related to age, resulting in the loss of the ability to perform daily behaviors and is a fundamental clinical neurodegeneration symptom. It has been proven that an adequate diet, comprehensive nutrition, and a healthy lifestyle may significantly inhibit neurodegenerative processes, improving cognitive functions. Therefore, intensive research has been conducted on cognitive-enhancing treatment for many years, especially with substances of natural origin. There are several intervention programs aimed at improving cognitive functions in elderly adults. Cognitive functions depend on body weight, food consumed daily, the quality of the intestinal microflora, and the supplements used. The effectiveness in the prevention of dementia is particularly high before the onset of the first symptoms. The impact of diet and nutrition on age-associated cognitive decline is becoming a growing field as a vital factor that may be easily modified, and the effects may be observed on an ongoing basis. The paper presents a review of the latest preclinical and clinical studies on the influence of natural antioxidants on cognitive functions, with particular emphasis on neurodegenerative diseases. Nevertheless, despite the promising research results in animal models, the clinical application of natural compounds will only be possible after solving a few challenges.

Brazilian green propolis promotes TNFR2 expression on regulatory T cells

FoxP3+ regulatory T cells (Tregs) are needed to suppress inflammatory diseases and maintain immune homeostasis. The suppressive function of Tregs can be used to control autoimmune or inflammatory diseases; therefore, it is well studied how Tregs can be artificially up- or downregulated in vitro and in vivo, by using antibodies, chemical compounds, foods, and natural resources. Propolis is a famous functional food that has an anti-inflammatory effect. However, the influences of propolis on Treg function have not been fully evaluated so far. Here, we demonstrated that Brazilian green propolis increases TNFR2 expression in Tregs via the IRF4/cMyc axis, and artepillin C was a major effective component of propolis on Tregs. These results indicate that propolis and artepillin C have the potential as Treg activators via TNFR2 expression and may be useful for the prevention and/or therapy of autoimmune or inflammatory diseases.

Effects of propolis supplementation on glycemic status, lipid profiles, inflammation and oxidative stress, liver enzymes, and body weight: a systematic review and meta-analysis of randomized controlled clinical trials

The aim of meta-analysis was to assess the effects of propolis on markers of oxidative stress, lipid profiles, inflammation and glycemic control, liver enzymes, and weight control. The heterogeneity between the included studies was indicated using the Cochrane's Q test and I-square (I2) statistic. 14 trials were included in this meta-analysis. Our meta-analysis indicated a significant reduction in fating glucose (WMD: -17.00; 95% CI: -30.88, -3.11), HbA1C (WMD: -0.42; 95% CI: -0.75, -0.10), and insulin (WMD: -1.75; 95% CI: -3.24, -0.26) and a marginally significant reduction in insulin resistance (WMD: -0.60; 95% CI: -1.20, 0.00) following propolis supplementation in 10, 8, 6, and 5 studies, respectively. Pooling 5 effect sizes, a significant reduction was seen in ALT (WMD: -5.63; 95% CI: -10.59, -0.67) and aspartate aminotransferase (AST) (WMD: -3.09; 95% CI: -5.15, -1.03) following propolis. A significant beneficial effect was observed for CRP (WMD: -1.11; 95% CI: -1.92, -0.29), TNF-α (WMD: -6.71; 95% CI: -9.44, -3.98) and interleukin-6 (IL-6) (WMD: -17.99; 95% CI: -35.56, -0.42) concentrations after propolis supplementation. This study demonstrated the beneficial effects of propolis on FPG, HbA1c, insulin, CRP, TNF-α and liver enzymes levels.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40200-020-00696-w.

Double-blinded randomized controlled trial to reveal the effects of Brazilian propolis intake on rheumatoid arthritis disease activity index; BeeDAI

Background and aims

Brazilian propolis reportedly contributed to suppressing disease activity in a mouse model of rheumatoid arthritis (RA), suggesting new treatment options using Brazilian propolis. However, only results from animal experiments have been available, and the suppressive effects of Brazilian propolis on disease activity in humans with RA remain unknown. The purpose of this study was to clinically validate how Brazilian propolis intake changes disease activity in RA patients.

Methods

This study was conducted as a multicenter, double-blinded, randomized, placebo-controlled, parallel-group study of 80 women with RA (median age, 61.5 years; interquartile range, 56.0 to 67.3 years) showing moderate disease activity on Disease Activity Score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR). Test tablets containing Brazilian propolis were used in Group P (40 patients), and Brazilian propolis-free placebo tablets were used as control in Group C (40 patients). Group P received 5 tablets of propolis (508.5 mg of propolis) daily, and Group C received 5 tablets of placebo daily. The intervention lasted 24 weeks, with change in DAS28-ESR set as the primary endpoint. As secondary endpoints, other disease activity assessment (DAS28 using C-reactive protein, simplified disease activity index, clinical disease activity index), ultrasonographic evaluation of synovitis, activities of daily living, quality of life, changes in cytokine levels, and adverse events over the course of the study were also assessed. Data were statistically analyzed by analysis of covariance.

Results

No significant differences in the primary endpoint were identified between groups (Group P vs Group C, effect: 0.14, 95% confidence interval: -0.21 to 0.49, p = 0.427). Likewise, no significant differences were seen between groups for any secondary endpoints. The adverse event rate during the study period was 28% in Group P and 33% in Group C.

Conclusions

Brazilian propolis exerted no effects on disease activity in patients with RA.

Pharmacokinetics and metabolism of cinnamic acid derivatives and flavonoids after oral administration of Brazilian green propolis in humans

Brazilian green propolis (BGP) has chemical compounds from botanical origin that are mainly cinnamic acid derivatives (artepillin C, baccharin, and drupanin) and flavonoids (kaempferide and 6-methoxykaempferide). These compounds are expected to play an important role in the pharmacological activities of BGP. However, there is little known about the pharmacokinetics and metabolism of these compounds after oral administration of BGP. The aim of this study is to investigate the pharmacokinetics and metabolism of BGP components in humans. Twelve volunteers received 3 capsules containing 360 mg of BGP ethanol extract powder. Plasma samples were collected before and up to 24 h after the intake of BGP capsules. The collected plasma samples with or without hydrolysis by the deconjugating enzyme were analyzed by LC/MS/MS. After enzymatic hydrolysis, the C_max values of artepillin C and drupanin, which were detected mainly in plasma after ingestion of BGP capsules, were 1255 ± 517 and 2893 ± 711 nM, respectively, of which 89.3% and 88.2% were found to be the phenolic glucuronide conjugate. This is the first time that the pharmacokinetics of the BGP components of human metabolites have been reported. Our results could provide useful information for the design and interpretation of studies to investigate the mechanisms and pharmacological effects of BGP.

Cognitive Improvement and Safety Assessment of a Dietary Supplement Containing Propolis Extract in Elderly Japanese: A Placebo-Controlled, Randomized, Parallel-Group, Double-Blind Human Clinical Study

Objectives. This study aimed to evaluate the effect of propolis on cognitive function in elderly Japanese with a placebo-controlled design. Material and Methods. This study was performed on 79 elderly Japanese. Participants orally received either a placebo or dietary supplement containing propolis extract for 24 weeks. Cognitive function assessed by Cognitrax and various blood or urine markers were measured at pre- and postadministration. Results and Conclusion. Eligible data from 68 subjects (placebo: 33, propolis: 35) who completed the study were analyzed. Compared to the placebo group, the propolis group showed significant improvement in verbal memory in Cognitrax (P=0.028). Total cholesterol, LDL cholesterol, urea nitrogen, creatinine, and uric acid were significantly improved in the propolis group compared to the placebo group (P = 0.011, P = 0.004, P = 0.048, P = 0.045, and P = 0.005, respectively). However, urea nitrogen, creatinine, and uric acid fluctuated within the normal level. Furthermore, a subgroup analysis was performed on those with higher than 100 of the standardized score of the neurocognitive index indicated by the overall Cognitrax score. Significant improvements in the propolis group compared to placebo were confirmed in verbal memory (P = 0.007) and processing speed as indications for information processing ability, complex attention, and concentration (P = 0.029). No side effects were observed in any of the groups. This study demonstrates that propolis is effective in improving cognitive functions such as memory, information processing, complex attention, and concentration in elderly Japanese.

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.

Inflammation Spreading: Negative Spiral Linking Systemic Inflammatory Disorders and Alzheimer's Disease

As a physiological response to injury in the internal body organs, inflammation is responsible for removing dangerous stimuli and initiating healing. However, persistent and exaggerative chronic inflammation causes undesirable negative effects in the organs. Inflammation occurring in the brain and spinal cord is known as neuroinflammation, with microglia acting as the central cellular player. There is increasing evidence suggesting that chronic neuroinflammation is the most relevant pathological feature of Alzheimer’s disease (AD), regulating other pathological features, such as the accumulation of amyloid-β (Aβ) and hyperphosphorylation of Tau. Systemic inflammatory signals caused by systemic disorders are known to strongly influence neuroinflammation as a consequence of microglial activation, inflammatory mediator production, and the recruitment of peripheral immune cells to the brain, resulting in neuronal dysfunction. However, the neuroinflammation-accelerated neuronal dysfunction in AD also influences the functions of peripheral organs. In the present review, we highlight the link between systemic inflammatory disorders and AD, with inflammation serving as the common explosion. We discuss the molecular mechanisms that govern the crosstalk between systemic inflammation and neuroinflammation. In our view, inflammation spreading indicates a negative spiral between systemic diseases and AD. Therefore, “dampening inflammation” through the inhibition of cathepsin (Cat)B or CatS may be a novel therapeutic approach for delaying the onset of and enacting early intervention for AD.

Association of Peripheral Plasma Neurotransmitters with Cognitive Performance in Chronic High-altitude Exposure

Long-term living at high altitude causes significant impairment of cognitive function. Central neurotransmitters are potential mediators of cognitive performance. We aimed to determine whether there were significant associations between select peripheral plasma neurotransmitters and cognitive performance in humans with chronic high-altitude (HA) exposure and to determine the association between peripheral plasma neurotransmitters and brain neurotransmitters in rats after chronic hypobaric hypoxia (HH) exposure. We demonstrated that 3,4-dihydroxy-L-phenylalanine (DOPA), dopamine, serotonin, 5-hydroxyindole-3-acetic acid (5-HIAA) and GABA in the peripheral plasma were associated with cognitive performance in humans with HA exposure. Consistent with this result, peripheral plasma DOPA, dopamine, serotonin, 5-HIAA and glutamate were associated with brain neurotransmitter levels after chronic HH exposure in rats. These results provide experimental data indicating that neurotransmitter levels and cognitive performance are modified in chronic high-altitude exposure, with a possible causal effect.

Propolis and its potential against SARS-CoV-2 infection mechanisms and COVID-19 disease: Running title: Propolis against SARS-CoV-2 infection and COVID-19

Propolis, a resinous material produced by honey bees from plant exudates, has long been used in traditional herbal medicine and is widely consumed as a health aid and immune system booster. The COVID-19 pandemic has renewed interest in propolis products worldwide; fortunately, various aspects of the SARS-CoV-2 infection mechanism are potential targets for propolis compounds. SARS-CoV-2 entry into host cells is characterized by viral spike protein interaction with cellular angiotensin-converting enzyme 2 (ACE2) and serine protease TMPRSS2. This mechanism involves PAK1 overexpression, which is a kinase that mediates coronavirus-induced lung inflammation, fibrosis, and immune system suppression. Propolis components have inhibitory effects on the ACE2, TMPRSS2 and PAK1 signaling pathways; in addition, antiviral activity has been proven in vitro and in vivo. In pre-clinical studies, propolis promoted immunoregulation of pro-inflammatory cytokines, including reduction in IL-6, IL-1 beta and TNF-α. This immunoregulation involves monocytes and macrophages, as well as Jak2/STAT3, NF-kB, and inflammasome pathways, reducing the risk of cytokine storm syndrome, a major mortality factor in advanced COVID-19 disease. Propolis has also shown promise as an aid in the treatment of various of the comorbidities that are particularly dangerous in COVID-19 patients, including respiratory diseases, hypertension, diabetes, and cancer. Standardized propolis products with consistent bioactive properties are now available. Given the current emergency caused by the COVID-19 pandemic and limited therapeutic options, propolis is presented as a promising and relevant therapeutic option that is safe, easy to administrate orally and is readily available as a natural supplement and functional food.

Antioxidant Effect of Standardized Extract of Propolis (EPP-AF®) in Healthy Volunteers: A "Before and After" Clinical Study

Background

Propolis is rich in polyphenols, especially flavonoids and phenolic acids, and has significant antioxidant activity, shown mainly in “in vitro” studies.

Objective

The aim of this study was to evaluate the antioxidant efficacy and safety of a standardized propolis extract in healthy volunteers.

Design

A two-phase sequential, open-label, nonrandomized, before and after clinical trial.

Methods

Healthy participants received two EPP-AF® doses (375 and 750 mg/d, P.O, tid) during 7 ± 2 days, starting with the lower doses. Immediately before starting EPP-AF® administration and at the end of each 7-day dosing schedule, blood and urine samples were collected for quantification of 8-OHDG (8-hydroxydeoxyguanosine) and 8-ISO (8-isoprostanes) in urine and GSH (reduced glutathione), GSSG (oxidized glutathione), SOD (superoxide dismutase), FRAP (Ferric Reducing Antioxidant Power), vitamin E, and MDA (malondialdehyde) in plasma.

Results

In our study, we had 34 healthy participants (67.7% women, 30 ± 8 years old, 97% white). The 8-ISO, a biomarker of lipid peroxidation, decreased with both doses of EPP-AF® compared to baseline (8-ISO, 1.1 (0.9–1.3) versus 0.85 (0.75–0.95) and 0.89 (0.74–1.0), ng/mg creatinine, P < 0.05, for 375 and 750 mg/d EPP-AF® doses versus baseline, mean and CI 95%, respectively). 8-OHDG, a biomarker of DNA oxidation, was also reduced compared to baseline with 750 mg/d doses (8-OHDG, 15.7 (13.2–18.1) versus 11.6 (10.2–13.0), baseline versus 750 mg/d, respectively, ng/mg creatinine, P < 0.05). Reduction of biomarkers of oxidative stress damage was accompanied by increased plasma SOD activity (68.8 (66.1–73.3) versus 78.2 (72.2–80.5) and 77.7 (74.1–82.6), %inhibition, P < 0.0001, 375 and 750 mg/d versus baseline, median and interquartile range 25–75%, respectively) and by increased GSH for 375 mg/d EPP-AF® doses (1.23 (1.06–1.34) versus 1.33 (1.06–1.47), μmol/L, P < 0.05).

Conclusion

EPP-AF® reduced biomarkers of oxidative stress cell damage in healthy humans, with increased antioxidant enzymatic capacity, especially of SOD. This trial is registered with the Brazilian Registry of Clinical Trials (ReBEC, RBR-9zmfs9).

Isolation, Identification, and Synthesis of a New Prenylated Cinnamic Acid Derivative from Brazilian Green Propolis and Simultaneous Quantification of Bioactive Components by LC-MS/MS

A new cinnamic acid derivative, (E)-3-[4-hydroxy-3-((E)-3-formyl-2-butenyl)phenyl]-2- propenoic acid (20) has been isolated from the ethanol extract of Brazilian green propolis along with three known cinnamic acid derivatives, 3,4-dihydroxy-5-prenyl-(E)-cinnamic acid (4), capillartemisin A (6), and 2,2-dimethylchromene-6-(E)-propenoic acid (8), and a flavonoid, dihydrokaempferide (16) by liquid-liquid participation, a series of column chromatography and preparative HPLC. Their structures have been determined by spectroscopic analyses and chemical synthesis of compound 20. The simultaneous quantification of 20 constituents, including 10 cinnamic acid derivatives, 7 flavonoids, and 3 caffeoylquinic acid derivatives, has also been developed and validated using LC-MS/MS. The new compound 20 was shown to activate PPAR α but not PPAR β or γ.

Evidence-Based Studies and Perspectives of the Use of Brazilian Green and Red Propolis in Dentistry

This review analyzes the evidence and perspectives of dental use of the green and red propolis produced in Brazil by Apis mellifera L. Multiple applications of propolis were found considering its antibacterial, antifungal, anti-inflammatory, immunomodulatory, antiviral, and healing properties. Its therapeutic effects are mainly due to the presence of alcohols, aldehydes, aliphatic acids, aliphatic esters, amino acids, aromatic acids, aromatic esters, flavonoids, hydrocarbyl esters, ethers, fatty acids, ketones, terpenes, steroids, and sugars. Propolis has been mainly used in dentistry in the composition of dentifrices and mouthwashes. Studies have also demonstrated promising use against dentin hypersensitivity, root canal treatment, Candida albicans, and other microorganisms. Overall review of the literature presented here demonstrated that both Brazilian green and red propolis are effective for the problems of multiple etiologies that affect the oral cavity in different dental specialties.