Total monoamine oxidase (MAO) inhibition by chestnut honey, pollen and propolis

Bee products: An overview of sources, biological activities and advanced approaches used in apitherapy application

Background

Bee therapy (Apitherapy, Api-treatment, Bee treatment) is a type of biotherapy that uses bees and their products as medicinal or preventative measures to control progression of diseases. In many countries today, apitherapy is a section of complementary and integrative medicine. The aim of this review is to explore the different bee products and their therapeutic potentials.

Method

We searched the literature and then explored and evaluated evidence for bee products' composition, therapeutic abilities and novel techniques used to enhance their effectiveness.

Results

Data revealed that there are continuous advances in research and clinical trials of bee therapy. A better understanding of the composition of bee products generated great interest in their use for medical treatments. Bee products either collected or synthesized promote healing through reducing inflammation, enhancing circulation, and inducing a healthy immunological response, Furthermore, researchers have developed innovative approaches such as nanoparticles, scaffold, nanofibers, and others to increase the bioavailability of bee products and overcome problems with the traditional use of these products.

Conclusion

Bee therapy is a simple, accessible, and easy-to-use pharmaceutical that is used in conventional medicine and has the potential to treat a variety of diseases. However, further studies are needed to prove its efficacy, and safety. Lack of practice regulations is still an issue.

Chemometric classification of chestnut honeys from different regions in Turkey based on their phenolic compositions and biological activities

The objective of this study was to investigate the phenolic composition and biological properties of chestnut honeys of 41 stations in Turkey's the Black Sea and Marmara regions. A total of sixteen phenolic compounds and organic acids were detected using HPLC-DAD and levulinic, gallic, protocatechuic, vanilic, trans-cinnamic acids and (4-hydroxyphenyl) ethanol were identified in all studied chestnut honeys. Antioxidant activities were measured by ABTS^•+, β-carotene-linoleic acid, CUPRAC, DPPH^•, and metal chelating assays. Antimicrobial activities were carried out against gram positive, gram negative bacteria and Candida species using well diffusion test. Anti-inflammatory activities were evaluated against COX-1 and COX-2 whereas enzyme inhibitory activities were assessed on AChE, BChE, urease, and tyrosinase. The chemometric classification of chestnut honeys were carried out using PCA and HCA and it was seen that some phenolic compounds contributed significantly to the classification of chestnut honeys from various geographical origin.

Honey on brain health: A promising brain booster

Since ancient times, honey has been employed in many aspects of everyday life, the most popular of which is as a natural sweetener. Honey is used not only as a nutritional product but also in health as a supplement and in various applications, especially related to brain booster health. Brain health is the capacity to carry out all mental functions necessary for cognition, such as learning and judging, utilizing language, and recalling. This review presents the current trend of research on honey, particularly the interest in underlying mechanisms related to brain booster health. A total of 34 original articles addressing brain health from the consumption of honey were analyzed. We identified four main brain health benefits, which are memory booster, neuroprotective effect, anti-stress, and anti-nociceptive potentials with the proposed underlying mechanism. A lot of attention has been paid to the role that honey plays in brain health research, with the goal of examining the link between honey and brain health as well as the mechanism underlying it, the findings from this review may be potentially beneficial to develop new therapeutic roles for honey to help determine the best and most promising to benefit and boost overall brain health.

A Review of the Health Benefits of Food Enriched with Kynurenic Acid

Kynurenic acid (KYNA), a metabolite of tryptophan, is an endogenous substance produced intracellularly by various human cells. In addition, KYNA can be synthesized by the gut microbiome and delivered in food. However, its content in food is very low and the total alimentary supply with food accounts for only 1-3% of daily KYNA excretion. The only known exception is chestnut honey, which has a higher KYNA content than other foods by at least two orders of magnitude. KYNA is readily absorbed from the gastrointestinal tract; it is not metabolized and is excreted mainly in urine. It possesses well-defined molecular targets, which allows the study and elucidation of KYNA's role in various pathological conditions. Following a period of fascination with KYNA's importance for the central nervous system, research into its role in the peripheral system has been expanding rapidly in recent years, bringing some exciting discoveries. KYNA does not penetrate from the peripheral circulation into the brain; hence, the following review summarizes knowledge on the peripheral consequences of KYNA administration, presents data on KYNA content in food products, in the context of its daily supply in diets, and systematizes the available pharmacokinetic data. Finally, it provides an analysis of the rationale behind enriching foods with KYNA for health-promoting effects.

Phytochemical content, especially spermidine derivatives, presenting antioxidant and antilipoxygenase activities in Thai bee pollens

Background

Bee pollen (BP) is full of useful nutrients and phytochemicals.Its chemical components and bioactivities depend mainly on the type of floral pollen.

Methods

Monofloral BP from Camellia sinensis L., Mimosa diplotricha, Helianthus annuus L., Nelumbo nucifera, Xyris complanata, and Ageratum conyzoides were harvested. Crude extraction and partition were performed to yield solvent-partitioned extracts of each BP. Total phenolic content (TPC) was assayed by the Folin-Ciocalteu method, while the flavonoid content (FC) was measured by the aluminium chloride colorimetric method. Antioxidant capacity was measured by the (i) 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, (ii) 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) scavenging activity and its Trolox equivalent antioxidant capacity (TEAC), and (iii) ferric reducing antioxidant power (FRAP). All samples were tested for lipoxygenase inhibitory (LOXI) activity. The most active sample was enriched by silica gel 60 column chromatography (SiG60-CC) and high performance liquid chromatography (HPLC), observing the chemical pattern of each fraction using thin layer chromatography. Chemical structure of the most active compound was analyzed by proton nuclear magnetic resonance and mass spectrometry.

Results

Dichloromethane (DCM)-partitioned BP extracts of H. annuus L. and M. diplotricha (DCMMBP) showed a very high TPC, while DCMMBP had the highest FC. In addition, DCMMBP had the strongest DPPH and ABTS radical scavenging activities (as a TEAC value), as well as FRAP value. Also, DCMMBP (60 µg/mL) gave the highest LOXI activity (78.60 ± 2.81%). Hence, DCMMBP was chosen for further enrichment by SiG60-CC and HPLC. Following this, the most active fraction showed higher antioxidant andLOXI activities with an EC₅₀ for DPPH and ABTS of 54.66 ± 3.45 µg/mL and 24.56 ± 2.99 µg/mL (with a TEAC value of 2,529.69 ± 142.16 µmole TE/g), respectively, and a FRAP value of 3,466.17 ± 81.30 µmole Fe²⁺/g and an IC₅₀ for LOXI activity of 12.11 ± 0.36 µg/mL. Triferuloyl spermidines were revealed to be the likely main active components.

Conclusions

TPC, FC, and spermidine derivatives played an important role in the antioxidant and antilipoxygenase activities in M. diplotricha bee pollen.

Potential Therapeutic Benefits of Honey in Neurological Disorders: The Role of Polyphenols

Honey is the principal premier product of beekeeping familiar to Homo for centuries. In every geological era and culture, evidence can be traced to the potential usefulness of honey in several ailments. With the advent of recent scientific approaches, honey has been proclaimed as a potent complementary and alternative medicine for the management and treatment of several maladies including various neurological disorders such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and multiple sclerosis, etc. In the literature archive, oxidative stress and the deprivation of antioxidants are believed to be the paramount cause of many of these neuropathies. Since different types of honey are abundant with certain antioxidants, primarily in the form of diverse polyphenols, honey is undoubtedly a strong pharmaceutic candidate against multiple neurological diseases. In this review, we have indexed and comprehended the involved mechanisms of various constituent polyphenols including different phenolic acids, flavonoids, and other phytochemicals that manifest multiple antioxidant effects in various neurological disorders. All these mechanistic interpretations of the nutritious components of honey explain and justify the potential recommendation of sweet nectar in ameliorating the burden of neurological disorders that have significantly increased across the world in the last few decades.

Optimisation of Bee Pollen Extraction to Maximise Extractable Antioxidant Constituents

This paper presents the findings of a comprehensive review on common bee pollen processing methods which can impact extraction efficiency and lead to differences in measured total phenolic content (TPC) and radical scavenging activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) data. This hampers the comparative analysis of bee pollen from different floral sources and geographical locations. Based on the review, an in-depth investigation was carried out to identify the most efficient process to maximise the extraction of components for measurement of TPC, DPPH and FRAP antioxidant activity for two bee pollen samples from western Australia (Jarrah and Marri pollen). Optimisation by Design of Experiment with Multilevel Factorial Analysis (Categorical) modelling was performed. The independent variables included pollen pulverisation, the extraction solvent (70% aqueous ethanol, ethanol, methanol and water) and the extraction process (agitation, maceration, reflux and sonication). The data demonstrate that non-pulverised bee pollen extracted with 70% aqueous ethanol using the agitation extraction method constitute the optimal conditions to maximise the extraction of phenolics and antioxidant principles in these bee pollen samples.

Investigation of potential inhibitor properties of ethanolic propolis extracts against ACE-II receptors for COVID-19 treatment by molecular docking study

The angiotensin-converting enzyme (ACE)-related carboxypeptidase, ACE-II, is a type I integral membrane protein of 805 amino acids that contains 1 HEXXH-E zinc binding consensus sequence. ACE-II has been implicated in the regulation of heart function and also as a functional receptor for the coronavirus that causes the severe acute respiratory syndrome (SARS). In this study, the potential of some flavonoids presents in propolis to bind to ACE-II receptors was calculated with in silico. Binding constants of ten flavonoids, caffeic acid, caffeic acid phenethyl ester, chrysin, galangin, myricetin, rutin, hesperetin, pinocembrin, luteolin and quercetin were measured using the AutoDock 4.2 molecular docking program. And also, these binding constants were compared to reference ligand of MLN-4760. The results are shown that rutin has the best inhibition potentials among the studied molecules with high binding energy − 8.04 kcal/mol, and it is followed by myricetin, quercetin, caffeic acid phenethyl ester and hesperetin. However, the reference molecule has binding energy of – 7.24 kcal/mol. In conclusion, the high potential of flavonoids in ethanolic propolis extracts to bind to ACE-II receptors indicates that this natural bee product has high potential for COVID-19 treatment, but this needs to be supported by experimental studies.

The Quality Specialities in Turkiye's Honies for Apitherapy

Objectives

In this study, the content of the honey produced by the flora of Turkey', physical, chemical and biological research aimed at active properties.

Methods

Searched the database EMBASE/Pubmed and Turkish Medicine Index research article about Turkiye honeys' specialities.

Results

Different botanical sources were caused, different kinds of chemical compositions of the honeys. The amount of HMF, pH, moisture, and acidity are the chemical qulity criteria of the honey. Carbohydrates are seem the most important components of honey. The glycemic index of the consumed honey is important. Turkiye's honey quality seems apropiate for using apitherapy.

Conclusion

Honey is the most important product of beekeeping all over the world in terms of economy and health. Manufacturers of honey should be careful while producing honey. They should be avoided unhealty situations and they should be obey the rules. These rules are the basis for protecting our health by consuming bee products.

Determination of natural radioactivity levels and gamma radiation attenuation coefficients in propolis samples and the study of its antioxidant properties

Thanks to its rich content, propolis has been used to protect the hive from all kinds of external influences and for disinfection by bees. Furthermore, it is an important marker for monitoring environmental pollution because the main sources of propolis are plant and secretions. So, the present study aimed to research radiation attenuation capability and the natural radioactivity level of propolis samples. For this reason, both natural radioactivity concentrations (226Ra, 232Th and 40K) and attenuation coefficients (Linear and Mass) in the propolis samples collected from 10 different points in Turkey were measured using high purity germanium detector (HPGe). The average natural radioactivity concentrations in samples were found to be 0.56 ± 0.19, 2.65 ± 0.31 and 70.08 ± 2.42 Bq/kg for 226Ra, 232Th and 40K, respectively. These values were much lower than the average world values (35 Bq/kg for 226Ra, 30 Bq/kg for 232Th and 400 Bq/kg for 40K) reported by United Nations Scientific Committee on Effects of Atomic Radiation (UNSCEAR) in foodstuff. The average linear attenuation coefficient, mass attenuation coefficients and half value layer values for gamma rays with 59.54 keV energy were determined as 0.1970 cm−1, 0.1831 cm2 g−1 and 3.56 cm, respectively. In addition, antioxidant properties of the samples were measured using total phenolic content and ferric reducing antioxidant power. Their correlations with radioactivity were investigated.

In vivo and in vitro anti-diabetic activity of ethanolic propolis extract

The study investigated whether ethanolic propolis extract would exhibit an anti-diabetic effect in rats. The animals were divided into four groups of five rats each. Diabetic rats received 30% or 15% propolis extract at a dosage of 0.5 ml/100 g for 4 weeks. Data for the diabetic groups treated with 30% and 15% propolis showed a decrease in blood sugar levels from 393 ± 192.7 to 154 ± 28.0 mg/dl and from 386 ± 141.1 to 331.5 ± 123.74 mg/dl, respectively. Compared with the diabetic control group, an improvement was observed in both groups treated with propolis at the pancreatic, hepatic, and renal tissue levels. Antioxidant capacity, phenolic analysis, and the inhibition of α-amylase and α-glucosidase were also tested using the propolis samples to support in vivo data. Chrysin and caffeic acid phenyl ester were the dominant phenolics. The IC₅₀ results for α-amylase (0.62 ± 0.00 μg/ml) and α-glucosidase (40.40 ± 0.09 μg/ml) were also encouraging. PRACTICAL APPLICATIONS: Bee products, non-synthetic compounds including propolis, are of great interest due to their potential therapeutic effects in metabolic disorders. The current study was designed and is now reported in order to confirm this potential benefit. The results obtained indicate that the higher concentration (30%) of ethanolic propolis extract exhibited excellent potential anti-diabetic activity by reducing blood sugar levels in diabetic rats. In addition, compared to the diabetic rat group, this extract exhibited a promising effect on the pancreatic, hepatic, and renal tissues of the propolis-treated groups. The current results indicate that propolis is a remarkable natural product with clinical potential in the treatment of diabetic disease.

Promising selective MAO-B inhibition by sesamin, a lignan from Zanthoxylum flavum stems

Monoamine oxidase inhibition is an important therapeutic approach for various neurodegenerative disorders. Reversible MAO inhibitors selectively targeting only one isoform possess substantial merit in terms of safety, efficacy, and side effect profile. This study aimed to isolate the secondary metabolites of Zanthoxylum flavum stems and evaluate their recombinant human MAO inhibition, antimicrobial, and antiprotozoal activities. As a result, fourteen compounds were isolated and identified (nine of them were reported from Z. flavum for the first time). Compound 3 (sesamin) exhibited potent selective MAO-B inhibition (IC₅₀ value of 1.45 ± 0.05 µM) which reported herein for the first time. Compound 2 showed selective MAO-A inhibition activity, compound 5 exhibited good trypanocidal activity, and compound 7 displayed moderate antibacterial activity. The promising MAO-B inhibitory activity of sesamin provoked us to further explore the kinetic properties, the binding mode, and the underlying mechanism of MAO-B inhibition by this lignan. This detailed investigation substantiated a reversible binding and mixed MAO-B catalytic function inhibition via sesamin (K_i: 0.473 ± 0.076 μM). Selectivity and reversibility of sesamin on MAO-B provide exciting prerequisites for further in vivo investigation to confirm its therapeutic potentiality.

Identification of selective and reversible LSD1 inhibitors with anti-metastasis activity by high-throughput docking

The overexpression of lysine specific demethylase 1 (LSD1) has been reported in various human tumors. There is increasing interest in targeting LSD1 with small molecules for cancer treatment. A released structure of an LSD1 kinase domain in complex with FAD was used to set up a low-cost high-throughput docking protocol for quick identification of LSD1 inhibitors. The most promising hit L05 was confirmed to be a potent, selective and reversible LSD1 inhibitor and displayed marked inhibition of colorectal cells migration without significant cytotoxicity.

Honeydew Honeys: A Review on the Characterization and Authentication of Botanical and Geographical Origins

The commercial interest in honeydew honeys (from the secretions of plants or the excretions of plant-sucking insects found on plants) is increasing because of their higher therapeutic properties compared with those of most blossom honeys (from nectar). However, honeydew honeys have been less studied than blossom honeys. In this work, studies carried out to characterize and authenticate honeydew honeys by their botanical and geographical origins have been reviewed. The identification of honey origins has been approached by two ways: by the analysis of chemical markers and by the development of analytical methodologies combined with multivariate analyses. Some compounds have been suggested as specific botanical markers of several honeydew honeys, such as quercitol and trans-oak lactone for oak honey, 2-aminoacetophenone and propylanisol for holm oak honey, and 1-chloro-octane and tridecane for pine honey. The presence of 3-carene and an unidentified compound in samples was proposed as a way discriminate between Greek and Turkish pine honeys. Chemometric analyses have been applied on chemical compositions and on physicochemical, microscopic, and spectral parameters and have proved to be valuable methods for authenticating honeydew honeys. Analytical methods based on spectral information are suitable for the routine control of honeydew-honey origins because they are fast and require easy sample preparations.

Chemical Composition and Biological Activities of Mono- and Heterofloral Bee Pollen of Different Geographical Origins

Recent research shows variations in pollen chemical constituents and, consequently, in their therapeutic properties. Mono and multifloral bee pollen extracts were investigated for antioxidant and enzyme inhibitory activity properties, phenolic compounds and fatty acid composition. Generally, Eucalyptus spp. and multifloral extracts exhibited potent inhibitory activity against α-amylase, acetylcholinesterase, tyrosinase, lipoxygenase, lipase and hyaluronidase. On the other hand, Miconia spp. demonstrated higher antihemolytic activity. Cocos nucifera and Miconia spp. extracts exhibited important antioxidant properties in the different assays (ABTS, DPPH, β-carotene/linoleic acid and reducing power). Moreover, these extracts had greater amounts of total phenols and flavonoids in comparison to others. The increase in antioxidant activity (decrease in EC₅₀ values) was accompanied by an increase in the amount of total phenols in the extracts. The pollen extracts contained linoleic acid and α-linolenic acid as major fatty acids, followed by palmitic acid, and oleic acid. In this study, differences were observed in both chemical constituents and biological activities of the samples related to the geographical and botanical origin of bee pollen.

Investigation of the inhibitory properties of some phenolic standards and bee products against human carbonic anhydrase I and II

Polyphenols are important secondary products of plants with the potential to inhibit carbonic anhydrases. The aim of this study was to investigate the inhibition effects of various phenolic standards, honey, propolis, and pollen species on human carbonic anhydrase I and II. The inhibition values (IC₅₀) of the phenolics (gallic acid, protocatechuic acid, quercetin, catechin, tannic acid, and chrysin) ranged from 0.009 to 0.32 μg/mL, tannic acid emerging as the best inhibitor. The inhibition values of three different types of honey, heather, rhododendron, and chestnut ranged between 2.32 and 25.10 μg/mL, the chestnut honeys exhibiting the best inhibition. The ethanolic extracts of pollen and propolis exhibited good inhibitory properties, with IC₅₀ values between 0.486 and 3.320 μg/mL. In order to evaluate the phenolic composition of bee products, phenolic profiles and total phenolic contents (TFC) were also measured. The inhibition ranking among the natural products studied was phenolic standards > propolis > pollen > honeys, and inhibition was related to TFC.

Analysis of volatile components from Melipona beecheii geopropolis from Southeast Mexico by headspace solid-phase microextraction

A head space solid-phase microextraction method combined with gas chromatography-mass spectrometry was developed and optimised to extract and analyse volatile compounds of Melipona beecheii geopropolis. Seventy-three constituents were identified using this technique in the sample of geopropolis collected. The main compounds detected include β-fenchene (14.53-15.45%), styrene (8.72-9.98%), benzaldehyde (7.44-7.82%) and the most relevant volatile components presents at high level in the geopropolis were terpenoids (58.17%).

Honey shows potent inhibitory activity against the bovine testes hyaluronidase

The purpose of this study was to investigate the anti-hyaluronidase activities of honeys from different botanical origins honeys in order to determine their anti-inflammatory properties. The total phenolic contents, total flavonoids and total tannin levels of six types of honey, chestnut, oak, heather, pine, buckwheat and mixed blossom, were determined. Concentration-related inhibition values were tested turbidimetrically on bovine testis hyaluronidase (BTHase) as IC50 (mg/mL). All honeys exhibited various concentration-dependent degrees of inhibition against BTHase. Inhibition values varied significantly depending on honeys' levels of phenolic contents, flavonoid and tannin. The honeys with the highest anti-hyaluronidase activity were oak, chestnut and heather. In conclusion, polyphenol-rich honeys have high anti-hyaluronidase activity, and these honeys have high protective and complementary potential against hyaluronidase-induced anti-inflammatory failures.

Honey as an apitherapic product: its inhibitory effect on urease and xanthine oxidase

The aim of this study was to evaluate new natural inhibitor sources for the enzymes urease and xanthine oxidase (XO). Chestnut, oak and polyfloral honey extracts were used to determine inhibition effects of both enzymes. In addition to investigate inhibition, the antioxidant capacities of these honeys were determined using total phenolic content (TPC), ferric reducing antioxidant power (FRAP), and DPPH radical scavenging activity assays. Due to their high phenolic content, chestnut and oak honeys are found to be a powerful source for inhibition of both enzymes. Especially, oak honeys were efficient for urease inhibition with 0.012-0.021 g/mL IC50 values, and also chestnut honeys were powerful for XO inhibition with 0.028-0.039 g/mL IC50 values. Regular daily consumption of these honeys can prevent gastric ulcers deriving from Helicobacter pylori and pathological disorders mediated by reactive oxygen species.

Alleviating exercise-induced muscular stress using neat and processed bee pollen: oxidative markers, mitochondrial enzymes, and myostatin expression in rats

BACKGROUND

The current study was designed to investigate the influence of monofloral Indian mustard bee pollen (MIMBP) and processed monofloral Indian mustard bee pollen (PMIMBP) supplementation on chronic swimming exercise-induced oxidative stress implications in the gastrocnemius muscle of Wistar rats.

METHODS

MIMBP was processed with an edible lipid-surfactant mixture (Captex 355:Tween 80) to increase the extraction of polyphenols and flavonoid aglycones as analyzed by UV spectroscopy and high performance liquid chromatography-photo diode array. Wistar rats in different groups were fed with MIMBP or PMIMBP supplements at a dose of 100 mg/kg, 200 mg/kg and 300 mg/kg individually, while being subjected to chronic swimming exercise for 4 weeks (5 d/wk). Various biochemical [superoxide dismutase (SOD), glutathione (GSH), malonaldehyde (MDA), nitric oxide (NO), and total protein content], mitochondrial (Complex I, II, III, and IV enzyme activity), and molecular (myostatin mRNA expression) parameters were monitored in the gastrocnemius muscle of each group.

RESULTS

Administration of both MIMBP (300 mg/kg) and PMIMBP (100 mg/kg, 200 mg/kg, and 300 mg/kg) wielded an antioxidant effect by significantly improving SOD, GSH, MDA, NO, and total protein levels. Further MIMBP (300 mg/kg) and PMIMBP (200 mg/kg and 300 mg/kg) significantly improved impaired mitochondrial Complex I, II, III, and IV enzyme activity. Significant down-regulation of myostatin mRNA expression by MIMBP (300 mg/kg) and PMIMBP (200 mg/kg and 300 mg/kg) indicates a muscle protectant role in oxidative stress conditions.

CONCLUSION

The study establishes the antioxidant, mitochondrial upregulatory, and myostatin inhibitory effects of both MIMBP and PMIMBP in exercise-induced oxidative stress conditions, suggesting their usefulness in effective management of exercise-induced muscular stress. Further, processing of MIMBP with an edible lipid-surfactant mixture was found to improve the therapeutic efficiency of pollen.

Monoamine oxidase inhibitory constituents of propolis: kinetics and mechanism of inhibition of recombinant human MAO-A and MAO-B

Propolis is the resinous material that bees gather from leaf buds, flowers and vegetables. Propolis extracts contain constituents with a broad spectra of pharmacological properties and are important ingredients of popular dietary supplements. Propolis extracts were evaluated in vitro for inhibition of recombinant human monoamine oxidase (MAO)-A and MAO-B. The dichloromethane extract of propolis showed potent inhibition of human MAO-A and MAO-B. Further fractionation identified the most active fractions as rich in flavonoids. Galangin and apigenin were identified as the principal MAO-inhibitory constituents. Inhibition of MAO-A by galangin was about 36 times more selective than MAO-B, while apigenin selectivity for MAO-A vs. MAO-B was about 1.7 fold. Apigenin inhibited MAO-B significantly more potently than galangin. Galangin and apigenin were further evaluated for kinetic characteristics and the mechanism for the enzymes’ inhibition. Binding of galangin and apigenin with MAO-A and -B was not time-dependent and was reversible, as suggested by enzyme-inhibitor binding and dissociation-dialysis assay. The inhibition kinetics studies suggested that galangin and apigenin inhibited MAO-A and -B by a competitive mechanism. Presence of prominent MAO inhibitory constituents in propolis products suggests their potential for eliciting pharmacological effects that might be useful in depression or other neurological disorders. The results may also have important implications in drug-dietary supplement interactions.