Biomedical subjects

Vassya Bankova

Publications and source records attributed to Vassya Bankova.

13 recordsLinked to original sources

PubMed2006

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 Pacific coastal forest that lay 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 good radical scavenging activity against DPPH. Obviously, Northern type propolis is a promising potential source of biologically active substances and deserves further investigation.

Acetophenones↗

PubMed2006

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).

Journal Article↗

PubMed2005

Chemical diversity of propolis and the problem of standardization.

Chemical variability of propolis is discussed with respect to the problem of standardization. Several chemical types of propolis are formulated, based on their plant source. Reliable criteria for chemical standardization of different propolis types are needed but such generally accepted criteria do not yet exist. The chemical profile of "poplar" propolis, typical for the temperate zone, can be characterized by the following parameters: total flavone and flavonol content, total flavanone and dihydroflavonol content, and total phenolics content. These parameters correlate better with the biological activity and are more informative that the quantification of individual components. There is still a lot of work to be done to achieve standardization of other propolis types. Working with standardized material will allow scientists to connect a particular chemical propolis type to a specific type of biological activity and formulate recommendations for mainstream practitioners.

Plants↗

PubMed2005

Modifying effect of propolis on dimethylhydrazine-induced DNA damage but not colonic aberrant crypt foci in rats.

Propolis is a honeybee product with several biological and therapeutic properties, including antimutagenic and anticarcinogenic activities. The effects of an aqueous extract of propolis (AEP) were evaluated on the formation of 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) and DNA damage in the colon of male Wistar rats by the ACF and Comet assays, respectively. AEP was administered orally at 0.01%, 0.03%, 0.1%, and 0.3% in the drinking water, which resulted in doses of approximately 12, 34, 108, and 336 mg/kg body weight/day. Animals were also given a single subcutaneous injection of 40 mg/kg DMH and sacrificed 4 hr later for evaluating DNA damage, or 4 doses of 40 mg/kg DMH, administered 2 doses/week for 2 weeks, and sacrificed 12 weeks after the last injection for evaluating ACF development in the distal colon. Administration of AEP either simultaneously with or after the DMH treatment resulted in no statistically significant reduction of ACF. In contrast, 0.01%, 0.03%, and 0.3% AEP, given simultaneously with DMH, reduced DNA damage induction in the mid and distal colon. However, 0.3% AEP alone increased DNA damage in the colon. In conclusion, AEP had no effect on the formation of DMH-induced ACF in rat colon, but it modulated DMH-induced DNA damage in colon cells. Further investigations are recommended in order to establish the conditions under which propolis produces either protective or deleterious effects.

Animals↗

PubMed2005

Effects of Brazilian and Bulgarian propolis on bactericidal activity of macrophages against Salmonella Typhimurium.

Propolis has been used in folk medicine since ancient times due to its many biological properties, such as antimicrobial, antiinflammatory, antioxidant, immunomodulatory activities, among others. Macrophages play an important role in the early phase of Salmonella infection. In this work, macrophages were prestimulated with Brazilian or Bulgarian propolis and subsequently challenged with Salmonella Typhimurium at different macrophage/bacteria ratio. After 60 min of incubation, cells were harvested with Triton-X to lyse the macrophages. To assess the bactericidal activity, the number of colony-forming units (CFU) of S. typhimurium was determined by plating 0.1 mL in Mueller Hinton agar. After 24 h, CFU were counted, and the percentage of bactericidal activity was obtained. Propolis from Brazil and Bulgaria enhanced the bactericidal activity of macrophages, depending on its concentration. Brazilian propolis seemed to be more efficient than that from Bulgaria, because of their different chemical composition. In Bulgaria, bees collect the material mainly from the bud exudate of poplar trees, while in Brazil, Baccharis dracunculifolia DC. was shown to be the main propolis source. Our data also showed that the increased bactericidal activity of macrophages involved the participation of oxygen (H(2)O(2)) and nitrogen (NO) intermediate metabolites.

Animals↗

PubMed2005

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.

Anti-Infective Agents↗

PubMed2005

Recent trends and important developments in propolis research.

The newest developments in propolis pharmacological research are summarized. The problem regarding biological studies, caused by the chemical variability of propolis, is discussed. The most important trends and developments in recent propolis research are outlined: biological studies performed with chemically characterized samples, bioassay-guided studies of active principles and comparative biological studies of propolis of different origin and chemical composition. These types of studies are extremely valuable with respect to propolis standardization and practical applications in therapy. They will allow scientists to connect a particular chemical propolis type to a specific type of biological activity and formulate recommendations for practitioners.

Journal Article↗

PubMed2004

New polyisoprenylated benzophenones from Venezuelan propolis.

Two new polyisoprenylated benzophenones, 18-ethyloxy-17-hydroxy-17,18-dihydroscrobiculatone A and 18-ethyloxy-17-hydroxy-17,18-dihydroscrobiculatone B, together with the known scrobiculatones A and B, were isolated from Venezuelan propolis. The scrobiculatones A and B showed significant antibacterial activity and moderate toxicity to Artemia salina nauplii.

Animals↗

PubMed2003

Bulgarian propolis induces analgesic and anti-inflammatory effects in mice and inhibits in vitro contraction of airway smooth muscle.

Propolis is a bee product, which has long been used in folk medicine for the management of different diseases. In this study we evaluated the analgesic and anti-inflammatory effects of a standard ethanolic extract of Bulgarian propolis (Et-Blg) in mice and its in vitro effect on airway smooth muscle. Et-Blg inhibited acetic acid-induced abdominal contortions with an ID(50) = 7.4 +/- 0.7 mg. kg(-1). In the formalin test, the extract caused a significant reduction in pain in mice treated with 100 mg. kg(-1) Et-Blg during the neurogenic phase and for the inflammatory phase with all doses of the extract, with an ID(50) = 2.5 +/- 0.4 mg. kg(-1). Et-Blg inhibited also the capsaicin-induced ear edema in mice; however, this extract was ineffective when assessed in the tail-flick and hot-plate thermal assays. The analgesic effect of Et-Blg was associated with the inhibition of inflammatory responses and not to a simple irritation of nervous terminals. In vitro, this extract inhibited the contraction of trachea smooth muscle induced by histamine (IC(50) = 50 +/- 5 microg. mL(-1)), capsaicin (IC(50) = 26.8 +/- 3 microg. mL(-1)), 80 mM KCl (IC(50) = 27.8 +/- 3 microg. mL(-1)), and carbachol (IC(50) = 54 +/- 2 microg. mL(-1)).

Analgesics, Non-Narcotic↗

PubMedDate not supplied

Validated methods for the quantification of biologically active constituents of poplar-type propolis.

The validation of rapid, low-cost spectrophotometric procedures for the quantification of the three main groups of bioactive substances (flavones and flavonols, flavanones and dihydroflavonols, and total phenolics) in poplar-type propolis has been performed. A spectrophotometric assay based on the formation of an aluminium chloride complex was applied for the quantification of total flavones and flavonols using galangin as standard. Because of the high amount of flavanones and dihydroflavonols in "poplar type" propolis, the introduction of a distinct procedure for their quantification was considered of special significance and the DAB9 colorimetric method was applied for the purpose. Total phenolic content was measured by the Folin-Ciocalteu procedure using a mixture of pinocembrin and galangin as a reference. The procedures were validated using a model mixture of compounds representing the poplar-type propolis composition as found in previous studies. The accuracy (recovery) varied in the range 84-109%, and the relative standard deviation was 0.5-6.2%. The developed spectrophotometric procedures were applied to six poplar type propolis samples. The results were verified independently by a HPLC procedure. The two sets of results agreed satisfactory, as proven by Student's t-test.

Anti-Infective Agents↗

PubMedDate not supplied

GC-MS of Crinum latifolium L. alkaloids.

A GC-MS analysis of underivatized alkaloids from leaves of Crinum latifolium was performed. From the identified 15 alkaloids, 9 were found for the first time in this plant. Almost all alkaloids belonged to the crinane type. Substantial changes in the methylation and oxidation pattern of the alkaloids at and after flowering were observed.

Alkaloids↗

PubMedDate not supplied

Chemical composition of European propolis: expected and unexpected results.

Ten propolis samples from Bulgaria, Italy and Switzerland were analyzed by GC-MS. As expected, most samples displayed the typical chemical pattern of "poplar" propolis: they contained pinocembrin, pinobanksin and its 3-O-acetate, chrysin, galangin, prenyl esters of caffeic and ferulic acids. Two samples differed significantly: one from the Graubünden Alpine region, Switzerland, rich in phenolic glycerides, and one from Sicily which contained only a limited number of phenolics and was rich in diterpenic acids.

Animals↗

PubMedDate not supplied

Volatile substances of the green alga Scenedesmus incrassatulus.

Volatile substances of the green microalga Scenedesmus incrassatulus, cultivated in fresh and salt water, were studied. Cultivation in fresh water diversifies volatile secondary metabolites. Hydrocarbons and derivatives of the acetate pathway predominate when algae are grown in salt water; isoprenoids and aromatics are more abundant after fresh water cultivation.

Alcohols↗