Propolis extracts obtained by low pressure methods and supercritical fluid extraction

Propolis is a natural product used for centuries by human kind, due to several evidenced biological activities: antioxidant, antimicrobial, anti-inflammatory, antitumor and anti-HIV. Extracts from propolis, used in food, pharmaceutical and cosmetic industries, present quality and composition related to the extraction method applied. Natural compounds with biological activity can be obtained by conventional techniques, such as Soxhlet and Maceration, or by alternative methods such as supercritical fluid extraction (SFE). Thus, the aim of this work was to compare propolis extraction yields obtained by different procedures, for instance, SFE in one stage, with CO₂ and CO₂ plus co-solvent, and SFE in two stages, as well as Soxhlet and Maceration as low pressure extraction methods using ethanol, ethyl acetate, chloroform, n-hexane, water and mixtures of water/ethanol. The operational conditions for SFE in one stage with pure CO₂ were: 30, 40 and 50 °C and from 100 to 250 bar. The SFE with co-solvent was performed at 150 bar and 40 °C and ethanol concentrations of 2, 5 and 7% (w/w). The highest yield was obtained by chloroform Soxhlet extraction (73 ± 2%, w/w) whereas for SFE the maximum yield was 24.8 ± 0.9%, using 5% ethanol as co-solvent. For SFE in two stages, 100 and 150 bar were used in the first stage while 250 and 300 bar were applied in the second stage, at 40 °C. The yields were 8.4 ± 0.7 (150 bar) and 5.1 ± 0.7 (250 bar), for stages 1 and 2, respectively. The chemical composition of the propolis material was determined by HPLC analysis. The experimental data were correlated using four models based on differential mass balance equations: (1) the Sovová’s model; (2) the logistic model (3) the diffusion model and (4) the simple single plate model (SSP). The logistic model provided the best adjustment for propolis SFE curves.     

Bioactivity of propolis from Santiago del Estero, Argentina, related to their chemical composition

Propolis, an extremely complex resinous material gathered by honeybees from various plant sources, exhibits valuable pharmacological and biological properties attributed to the presence of polyphenols. This study examined the antibacterial, antiradical and antioxidant activities of propolis from different provenances and correlated the values with total levels of polyphenolic compounds and flavonoids. Besides, individual contents of those polyphenols with antioxidant ability were determined and related with their bioactivity. Analyzed samples presented a noticeable variability in their antioxidant and antiradical activities, although, linear relationships were found between them and also between polyphenol and flavonoid total levels. Propolis antiradical and protective abilities against lipid oxidation are related to its high levels of polyphenols, but their correlations with individual active-compound contents were not simple. Antibacterial activity against Staphylococcus aureus of the samples presented low variability. This bioactivity is assigned to pinocembrin, present in high concentrations in all the samples studied. Good correlation was found between such activity and pinocembrin content. Linear relationships between antibacterial activity and polyphenol and flavonoid total levels were also found.     

Effect of vapors from fractionated samples of propolis on microbial and oxidation damage of rice during storage

The efficacy of vapors from polar and non-polar sub-fractions of propolis on microbial and oxidation control during rice (Oryza sativa, hinohikari var.) storage was evaluated. The sub-fractions (absolute ethanol, methylene chloride, hexane extracts: AEPEV, MCPEV and HEPEV, respectively) were infused in synthetic adsorbents and their volatiles released during storage (6 months). HEPEV, MCPEV and AEPEV treatments inhibited molding and post-inoculation bacterial colonization (1.1, 1.1, 0.9 and 1.3, 1.2, 1.1 log₁₀ cfu/g reductions, respectively) on brown rice. AEPEV treatment suppressed fat acidity damage of milled rice at 30 °C to conventional cold storage level (5 °C) and differential Gram staining of bacteria isolated after the treatment indicated a dominant Gram-positive bacterial distribution. The concentrations providing 50% inhibition of 2′,2′-diphenylpicrylhydrazyl free radical scavenging were 9.8, 3.2 and 2.8 μg/μl for hexane (HEPE), absolute ethanol (AEPE) and methylene chloride (MCPE) extracts, respectively. The oxidative degradation rate was lowest for AEPE (4.3 × 10⁻⁴ min⁻¹) and highest for HEPE (1.9 × 10⁻³ min⁻¹) in the β-carotene bleaching assay. Gas chromatograph mass spectrometry revealed that AEPE had the highest amount of caffeic acid and caffeic acid phenethyl ester. Ultimately, the volatiles from the propolis sub-fractions had varied potential in rice quality preservation.     

蜂胶对氡及其子体吸入致大鼠损伤的防护作用研究

研究蜂胶对氡及其子体吸入致大鼠血细胞与肺氧化应激损伤的防护效应。采用雄性Wistar大鼠28只,随机分为7组,每组4只。染氡＋蜂胶组大鼠于每次吸入氡及其子体前灌服蜂胶0．2g／kg。除对照组外,各处理组整体暴露于多功能生态氡室,吸入氡及其子体的累积剂量分别达到30、67、111工作水平月（Working level month,WLM）后,检测各组大鼠外周血以及肺组织匀浆的超氧化物歧化酶（Superoxide dismutase,SOD）、丙二醛（Malonic dialdehyde,MDA）含量。结果表明,大鼠的外周血以及肺组织中SOD含量,随着氡及其子体染氡剂量的增加而降低,而MDA的含量呈现相反方向的变化。与30WLM染氡组相比,30WLM染氡＋蜂胶组大鼠肺匀浆MDA含量显著降低。与67WLM染氡组相比,67WLM染氡＋蜂胶组大鼠肺匀浆SOD活性显著提高,外周血和肺匀浆MDA含量显著降低。与111WLM染氡组相比,111WLM染氡＋蜂胶组大鼠外周血和肺匀浆SOD活性显著提高,MDA含量显著降低。在本实验条件下,氡及其子体吸入可引起大鼠的氧化损伤。蜂胶能够增强大鼠的抗氧化应激能力。     

Chemical composition,oral toxicity and antimicrobial activity of Iranian propolis

Propolis is a resinous natural hive product derived from plant exudates collected by honeybees. Due to biological and pharmacological activities, it has been extensively used in folk medicine. The present study was designed to investigate the chemical composition, subchronic toxicity, antimicrobial activity of Iranian propolis ethanolic extract, which has not been studied previously. One hundred and nine compounds were identified by gas chromatography–mass spectrometry analysis. Forty-five days subchronic toxicity of oral propolis extract was investigated in male rats. During the study no significant behavioral and clinical toxicity has been seen in animals however, hematologic, blood biochemistry and histopathologic data studies exhibited some significant differences between the groups. The ethanolic extract of propolis inhibited the growth of all examined microorganisms including bacteria and fungi with the highest antimicrobial activity against Gram-positive bacteria such as Staphylococcus aureus and Staphylococcus epidermidis.     

蜂胶微胶囊粉末的研究

介绍了一种蜂胶活性成分，提取物的微胶囊化方法，对壁材的制取和微胶囊化工艺过程进行了论述与讨论。该法制取的蜂胶微胶囊粉末产品包理率达95％以上，在水中的溶解性，分散性良好。     

Multiresidue determination of tetracycline antibiotics in propolis by using HPLC-UV detection with ultrasonic-assisted extraction and two-step solid phase extraction

An analytical method in propolis was developed and validated for the determination of four tetracyclines (TCs) by high performance liquid chromatography (HPLC) for the first time. After extraction by ultrasound, the extracting solution was subjected to Oasis HLB and weak cation-exchange cartridge to remove water-soluble and fat-soluble flavonoids, aromatic acids, terpenoid compounds, wax, and pollen debris. The calibration curves of fortified samples showed acceptable linear response (R² > 0.99) through a range of 100–5000 ng g⁻¹ in 20 replicates of six concentrations and the analysis of variance (ANOVA) was performed to validate the regression data. The limit of quantification of four TCs were 100 and 150 ng g⁻¹, respectively. The recoveries of the four TCs for propolis samples spiked with 100–500 ng g⁻¹ were in the range of 61.9–88.5% and the RSDs were between 4.80% and 13.2%. Traces of tetracycline were found in two out of 30 analysed real samples.     

A Proposal for Physicochemical Standards and Antioxidant Activity of Portuguese Propolis

Propolis is a complex resinous product gathered by honeybees whose chemical composition is highly variable, depending strongly on the plant sources available to the bees at the site of collection. Propolis from several locations in Portugal, including islands, was fully characterized in terms of physicochemical properties, phenolic composition and antioxidant activity, enabling the establishment of quality standards. Color, frequently used as a commercial parameter, was accessed by the first time in propolis with the CIELAB system, and proposed as a quick and reliable method for quality recognition. The results attested the existence of two different types of propolis within the six regions under study. One, the poplar propolis most common in temperate regions, revealed a high content in phenolics and show high bioactivity. The other, with darker green color is less rich in phenolics and generally less bioactive.     

Food preservative based on propolis: Bacteriostatic activity of propolis polyphenols and flavonoids upon Escherichia coli

Propolis was tested as food preserver, due its recognized bactericidal and bacteriostatic properties. Furthermore, most propolis components are natural constituents of food and recognized as safe substances. Fifteen propolis from Santa Fe, Argentine in 20% w/w ethanolic extracts, were tested upon Escherichia coli ATCC 25922 by agar diffusion and plate culture methods. Considering propolis physicochemical characteristics and inhibitory effects, tested samples were classified in three groups. A minimum inhibitory concentration mean value of 14.3 ± 6 mg soluble compounds/ml of the most active propolis was capable of inhibiting 10⁵ cfu/ml cellular concentration. Such extract had 32.31% total soluble compounds (2.1% coumaric + siringic acids, 5.16% quercetin, 0.47 apigenine, 8.15 galangine, 7.2 caffeic acid + crisine and 9.23% no-identified phenolics compounds). By relating the zone of growth inhibition with extracts concentration, a linear response was obtained. On the propolis samples tested, a single value of the minimum inhibitory concentration could not be established. Those values were strongly dependent on propolis composition and botanical origin. The propolis extracts tested, may successfully inhibit the E. coli development in vitro, and consequently may be useful as natural food preserver.     

Elastic Polymeric Network Structure for Slow Release Drug Delivery Systems

Network structures based on poly(lactic acid)(PLA) were prepared for use as drug carriers to improve the effectiveness of drug therapy. A prepolymer precursor, with low molecular weight (5148), as determined by Gel Permeation Chromatography (GPC), was prepared by polycondensation of poly(lactic acid) with hydrolyzed ?-caprolactone. A second step that is necessary to increase the molecular weight and build up a network structure with elastic properties involved further polycondensation with stoichiometric amount of 1,6-hexamethylene diisocyanate to finally obtain Poly(ester urethane) with a molecular weight of 25680. The physicomechanical properties of the resulting polymeric networks were evaluated and the one that found to exhibit the best combination of tensile strength (3.83 MPa) and elongation at break (646%) was selected for slow release applications. Propolis and Doxorubicin as bioactive materials were incorporated into the selected sample and shaped in the form of circular discs with 0.9 cm diameter and 0.4 cm thickness. The discs containing the bioactive materials were subjected to a buffer solution at pH 7.4, and the release rates of Propolis and Doxorubicin were measured spectrophotometrically and found to be 35 µg/L/day and 70 µg/L/day for Propolis and Doxorubicin, respectively over a prolonged time of 15 days.