Propolis is a natural substance produced by honeybees upon collection and transformation of resins and exudates from plants. Comparative studies on propolis collected from a wide range of countries are crucial for linking its provenance to antibacterial activity and thus ensuring that the beneficial properties of propolis are used more efficiently by the general public. This study reports the in vitro screening of ethanol extracts of propolis (n = 40), collected from a wide range of countries within the tropical, subtropical and temperate zones, and on the comparison of their activity against a range of Gram-positive and Gram-negative bacteria using a broth microdilution assay. The results obtained revealed that propolis extracts were mostly active against Gram-positive bacteria. The samples were subjected to principal component analysis (PCA) in order to model their activity against Gram-positive microorganisms. Three distinct clusters were distinguished in the PCA mapping based on MIC values, categorizing samples with strong (MIC range 3.9-31.25 mg/L), moderate (MIC range 31.25-> or =500 mg/L) and weak antibacterial activity or inactivity (MIC > or = 500 mg/L only). It is hypothesized that for samples of tropical provenance differences in the activity profiles may depend on the climatic characteristics of the collection sites. High antibacterial activity was observed for samples from locations characterized by a wet-tropical rainforest-type climate.

Propolis is a complex phytocompound made from resinous and balsamic material harvested by bees from flowers, branches, pollen, and tree exudates.Humans have used propolis therapeutically for centuries. The aim of this article is to provide comprehensive review of the antiviral, antibacterial, antifungal, and antiparasitic properties of propolis. The mechanisms of action of propolis are discussed. There are two distinct impacts with regards to antimicrobial and anti-parasitic properties of propolis, on the pathogens and on the host. With regards to the pathogens, propolis acts by disrupting the ability of the pathogens to invade the host cells by forming a physical barrier and inhibiting enzymes and proteins needed for invasion into the host cells. Propolis also inhibits the replication process of the pathogens. Moreover, propolis inhibits the metabolic processes of the pathogens by disrupting cellular organelles and components responsible for energy production. With regard to the host, propolis functions as an immunomodulator. It upregulates the innate immunity and modulates the inflammatory signaling pathways. Propolis also helps maintain the host’s cellular antioxidant status. More importantly, a small number of human clinical trials have demonstrated the efficacy and the safety of propolis as an adjuvant therapy for pathogenic infections.

No abstract

Introduction A previous study showed the unique character of Nigerian red propolis from Rivers State, Nigeria (RSN), with regards to chemical composition and activity against Trypanosoma brucei in comparison with other African propolis. Objective To carry out fractionation and biological testing of Nigerian propolis in order to isolate compounds with anti‐trypanosomal activity. To compare the composition of the RSN propolis with the composition of Brazilian red propolis. Methodology Profiling was carried out using HPLC‐UV‐ELSD and HPLC‐Orbitrap‐FTMS on extracts of two samples collected from RSN with data extraction using MZmine software. Isolation was carried out by normal phase and reversed phase MPLC. Elucidation of the compounds with a purity > 95% was performed by 1D/2D NMR HRMS and HRLC‐MSn. Results Ten phenolic compounds were isolated or in the case of liquiritigenin partially purified. Data for nine of these correlated with literature reports of known compounds i.e. one isoflavanone, calycosin (1); two flavanones, liquiritigenin (2) and pinocembrin (5); an isoflavan, vestitol (3); a pterocarpan, medicarpin (4); two prenylflavanones, 8‐prenylnaringenin (7) and 6‐prenylnaringenin (8); and two geranyl flavonoids, propolin D (9) and macarangin (10). The tenth was elucidated as a previously undescribed dihydrobenzofuran (6). The isolated compounds were tested against Trypanosoma brucei and displayed moderate to high activity. Some of the compounds tested had similar activity against wild type T. brucei and two strains displaying pentamidine resistance. Conclusion Nigerian propolis from RSN has some similarities with Brazilian red propolis. The propolis displayed anti‐trypanosomal activity at a potentially useful level. Copyright © 2015 John Wiley & Sons, Ltd.

Profiling of extracts from twelve propolis samples collected from eight regions in Nigeria was carried out using high performance liquid chromatography (LC) coupled with evaporative light scattering (ELSD), ultraviolet detection (UV) and mass spectrometry (MS), gas chromatography mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR). Principal component analysis (PCA) of the processed LC-MS data demonstrated the varying chemical composition of the samples. Most of the samples were active against Trypanosoma b. brucei with the highest activity being in the samples from Southern Nigeria. The more active samples were fractionated in order to isolate the component(s) responsible for their activity using medium pressure liquid chromatography (MPLC). Three xanthones, 1,3,7-trihydroxy-2,8-di-(3-methylbut-2-enyl)xanthone, 1,3,7-trihydroxy-4,8-di-(3-methylbut-2-enyl)xanthone a previously undescribed xanthone and three triterpenes: ambonic acid, mangiferonic acid and a mixture of α-amyrin with mangiferonic acid (1:3) were isolated and characterised by NMR and LC-MS. These compounds all displayed strong inhibitory activity against T.b. brucei but none of them had higher activity than the crude extracts. Partial least squares (PLS) modelling of the anti-trypanosomal activity of the sample extracts using the LC-MS data indicated that high activity in the extracts, as judged from LCMS2 data, could be correlated to denticulatain isomers in the extracts.

Extracts from twelve samples of propolis collected from different regions of Libya were tested for their activity against Trypanosoma brucei, Leishmania donovani, Plasmodium falciparum, Crithidia fasciculata and Mycobacterium marinum and the cytotoxicity of the extracts was tested against mammalian cells. All the extracts were active to some degree against all of the protozoa and the mycobacterium, exhibiting a range of EC50 values between 1.65 and 53.6 μg/ml. The toxicity against mammalian cell lines was only moderate; the most active extract against the protozoan species, P2, displayed an IC50 value of 53.2 μg/ml. The extracts were profiled by using liquid chromatography coupled to high resolution mass spectrometry. The data sets were extracted using m/z Mine and the accurate masses of the features extracted were searched against the Dictionary of Natural Products (DNP). A principal component analysis (PCA) model was constructed which, in combination with hierarchical cluster analysis (HCA), divided the samples into five groups. The outlying groups had different sets of dominant compounds in the extracts, which could be characterised by their elemental composition. Orthogonal partial least squares (OPLS) analysis was used to link the activity of each extract against the different micro-organisms to particular components in the extracts.

Chemical investigation of a sample of propolis originating from North-Western Cameroon led to the isolation of thirteen alk(en)ylphenols (1-13) (inseparable mixture) along with α-amyrin (14), β-amyrin (15), lupeol (16), cycloartenol (17), mangiferonic acid (18), ambonic acid (19), mangiferolic acid (20), ambolic acid (21), isomangiferolic acid (22) and nine alk(en)ylresorcinols (23-31) (inseparable mixture). All compounds were identified following analysis of their spectroscopic data and comparison with previously published reports. Compounds (8), (12), (13) and (30) are new natural products. GC-MS analysis carried out on the alk(en)ylphenol and alk(en)ylresorcinol mixtures (dimethyl disulphide trimethylsilyl derivatives) revealed the presence of saturated and mono-unsaturated compounds with side chain lengths ranging from C11 to C19 and C15 to C19, respectively. The position of the double bond in mono-unsaturated derivatives was established from the characteristic fragments resulting from the cleavage of the bond between the two methylthio-substituted carbons. The most abundant compound in each mixture was 3-(12'Z-heptadecenyl)-phenol (10) and 5-(12'Z-heptadecenyl)-resorcinol (29). This study is the first to report the presence of triterpenes (except for lupeol) and phenolic lipids, including eighteen compounds previously unreported in bee glue, in an African sample.

The need to discover and develop alternative therapies to treat methicillin-resistant Staphylococcus aureus (MRSA) infections is timely. This study was undertaken to purify and identify some anti-MRSA constituents from propolis, a natural product from the beehive traditionally used in folk medicine for its antimicrobial properties. A crude extract of propolis originating from the Solomon Islands ('Pacific propolis') was screened, using an agar dilution assay, in vitro against 15 MRSA clinical isolates. Results revealed activity worthy of further investigation, and subsequent purification work on this crude extract afforded 23 fractions. Further purification of active fractions led to the isolation of compounds 1-4, characterized upon analysis of their spectroscopic data (1D- and 2D-NMR, MS) and by comparison with the literature, as the prenylflavanones propolin H (1), propolin G (2), propolin D (3), and propolin C (4). This study is the first to report the anti-MRSA activity of 'Pacific propolis' and the presence of prenylflavanones in the propolis sample selected. The anti-MRSA activity of propolin D (3) (MIC 8-16 mg/L) and propolin C (4) (MIC 8-32 mg/L) is reported for the first time.