Boryana Trusheva

Bioactive Constituents of Brazilian Red Propolis

In a new propolis type, red Brazilian propolis, 14 compounds were identified (six of them new for propolis), among them simple phenolics, triterepenoids, isoflavonoids, prenylated benzophenones and a naphthoquinone epoxide (isolated for the first time from a natural source). Three of the major components demonstrated significant antimicrobial activity, and two (obtained as inseparable mixture) possessed radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH).

Different extraction methods of biologically active components from propolis: a preliminary study

BackgroundPropolis is widely used in apitherapy, preparations, and food and beverage additives. Various extraction techniques were applied in the extraction of the biologically active constituents of poplar type propolis in order to compare their efficiency. The methods employed were: traditional maceration extraction, ultrasound extraction (UE), and microwave assisted extraction (MAE).ResultsThe total amounts of extracted phenolics and flavonoids were determined, and the effectiveness of the methods compared. MAE was very rapid but led to the extraction of a large amount of non-phenolic and non-flavonoid material. UE gave the highest percentage of extracted phenolics.ConclusionCompared to the maceration extraction, MAE and UE methods provided high extraction yield, requiring short timeframes and less labour. UE was shown to be the most efficient method based on yield, extraction time and selectivity.

Chemical composition of propolis from Canada, its antiradical activity and plant origin.

The chemical composition of propolis from two regions in Canada was studied: Boreal forest and the Pacific coastal forest that lie outside the area of distribution of Aigeiros poplars, the usual propolis source plants. In the sample from Victoria, p-hydroxyacetophenone, benzyl hydroxybenzoate and cinnamic acid were the major components, accompanied by significant amounts of dihydrochalcones, which allowed the identification of its plant source: Populus trichocarpa of section Tacamahaca. Three dihydrochalcones were new for propolis. The sample from Richmond was characterized by large amounts of p-coumaric and cinnamic acid, typical for poplars of section Leuce, subsection Trepidae, its plant source was identified as P. tremuloides. Both samples showed a good radical scavenging activity against DPPH. Obviously, the Northern type propolis is a promising potential source of biologically active substances and deserves further investigation.

Propolis volatile compounds: chemical diversity and biological activity: a review

Propolis is a sticky material collected by bees from plants, and used in the hive as building material and defensive substance. It has been popular as a remedy in Europe since ancient times. Nowadays, propolis use in over-the-counter preparations, “bio”-cosmetics and functional foods, etc., increases. Volatile compounds are found in low concentrations in propolis, but their aroma and significant biological activity make them important for propolis characterisation. Propolis is a plant-derived product: its chemical composition depends on the local flora at the site of collection, thus it offers a significant chemical diversity. The role of propolis volatiles in identification of its plant origin is discussed. The available data about chemical composition of propolis volatiles from different geographic regions are reviewed, demonstrating significant chemical variability. The contribution of volatiles and their constituents to the biological activities of propolis is considered. Future perspectives in research on propolis volatiles are outlined, especially in studying activities other than antimicrobial.

Indonesian propolis: chemical composition, biological activity and botanical origin

From a biologically active extract of Indonesian propolis from East Java, 11 compounds were isolated and identified: four alk(en)ylresorcinols (obtained as an inseparable mixture) (1–4) were isolated for the first time from propolis, along with four prenylflavanones (6–9) and three cycloartane-type triterpenes (5, 10 and 11). The structures of the components were elucidated based on their spectral properties. All prenylflavanones demonstrated significant radical scavenging activity against diphenylpicrylhydrazyl radicals, and compound 6 showed significant antibacterial activity against Staphylococcus aureus. For the first time Macaranga tanarius L. and Mangifera indica L. are shown as plant sources of Indonesian propolis.

Antibacterial mono- and sesquiterpene esters of benzoic acids from Iranian propolis

BackgroundPropolis (bee glue) has been used as a remedy since ancient times. Propolis from unexplored regions attracts the attention of scientists in the search for new bioactive molecules.ResultsFrom Iranian propolis from the Isfahan province, five individual components were isolated: the prenylated coumarin suberosin 1, and four terpene esters: tschimgin (bornyl p-hydroxybenzoate) 2, tschimganin (bornyl vanillate) 3, ferutinin (ferutinol p-hydroxybenzoate) 4, and tefernin (ferutinol vanillate) 5. All of them were found for the first time in propolis. Compounds 2 - 5 demonstrated activity against Staphylococcus aureus.ConclusionsThe results of the present study are consistent with the idea that propolis from unexplored regions is a promising source of biologically active compounds.

New anti-Paenibacillus larvae substances purified from propolis

Propolis plays an important role in the exogenous defense of honeybee colony against pathogens. However, the studies dealing with the activity of propolis against bee pathogens are scarce. Poplar propolis extracts demonstrated promising activity against Paenibacillus larvae, the causative agent of American foulbrood. From the same propolis, five individual components and a mixture of caffeates were isolated, and their structures confirmed by spectroscopic data. Among the isolated propolis constituents are flavonoids, ferulic acid esters, and the oxylipin 9-oxo-10(E)-12(Z)-octadecadienoic acid, newly identified as propolis component. These substances were tested for their activity against P. larvae strains. The most active constituents were pinocembrin, 3-O-acetyl pinobanksin, and the caffeate mixture. This is the first communication of antimicrobial activity of individual propolis constituents against P. larvae; their important advantage is the fact that they are naturally present in the hive.

Standard methods for Apis mellifera propolis research

Propolis is one of the most fascinating honey bee (Apis mellifera L.) products. It is a plant derived product that bees produce from resins that they collect from different plant organs and with which they mix beeswax. Propolis is a building material and a protective agent in the bee hive. It also plays an important role in honey bee social immunity, and is widely used by humans as an ingredient of nutraceuticals, over-the-counter preparations and cosmetics. Its chemical composition varies by geographic location, climatic zone and local flora. The understanding of the chemical diversity of propolis is very important in propolis research. In this manuscript, we give an overview of the available methods for studying propolis in different aspects: propolis in the bee colony; chemical composition and plant sources of propolis; biological activity of propolis with respect to bees and humans; and approaches for standardization and quality control for the purposes of industrial application.

Novel micellar form of poplar propolis with high cytotoxic activity

A novel micellar form of propolis based on a biocompatible poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) block copolymer (PEO26PPO40PEO26) is developed. Beneficially, all biologically active lipophilic constituents of propolis are solubilized with the aid of polymeric micelles in aqueous media. The micellar form of the propolis exhibits high in vitro cytotoxicity at relatively low concentrations.

New cycloartane triterpenes from bioactive extract of propolis from Pitcairn Island

Dichloromethane extract of propolis (DCME) originating from Pitcairn Island demonstrated potent cytotoxicity against triple-negative MDA-MB-231 human breast carcinoma cells. The results from MTT assay showed that DCME inhibits the growth of the cancer cells in a dose- and time-dependent manner and upon the cell growth inhibition propolis extract provoked apoptotic changes in the cell nuclei. A detailed chemical investigation of DCME led to the isolation of four new cycloartane triterpenes (1-4), along with 17 known compounds (5-21). The structures of the new compounds were elucidated by means of extensive analysis of their spectroscopic data and comparison with those reported for their analogues. In vitro antimicrobial activity of new compounds (1-4) along with the DCME against four human pathogens was evaluated. All tested constituents except compound 2 were highly active against Escherichia coli with MIC 64 μg/ml. Compound 1 exhibited high antifungal activity against Candida albicans with potency close to that of the positive control (amphotericin B). The DCME showed very good antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans. This is the first study on propolis from Pitcairn Island.