Effect of propolis in the treatment of experimental Staphylococcus aureus keratitis in rabbits

Toxicity of Propylene Glycol Extract of Propolis on Central Nervous System and Liver in Pregnant and Neonatal Rats

BACKGROUND

Propolis has become one of the most preferred supplements due to its beneficial biological properties. Organic (water and vegetable oils) and chemical (ethyl alcohol, propylene glycol, and glycerol) solvents are used for propolis extraction. However, the effects of these chemicals on health should be taken into account.

OBJECTIVES

In this study, the effects of propolis extracts on health were evaluated.

METHODS

32 pregnant Wistar albino rats and 64 neonatal/young adults were given three different extractions of propolis (propylene glycol, water, and olive oil). Histopathological analyses were performed on the liver and brain, and blood samples were taken from the hearts of rats.

RESULTS

Histopathological scoring showed that the intensity of pycnotic hepatocyte, sinusoidal dilatation, and bleeding was high in liver samples of pregnant and baby rats given propylene glycol extract of propolis (p<0.05). Propylene glycol extract caused dilatation of blood vessels and apoptosis of neurons in brain tissue. The histopathological score was significantly lower in liver and brain tissues of rats treated with water and olive oil extract compared to propylene propolis groups (p<0.05). Liver enzyme levels in the blood increased in propylene propolis rats (p<0.05).

CONCLUSION

Histopathological changes and biochemical alterations may indicate that propylene glycol extracts of propolis are more toxic than olive oil and water extracts. Therefore, olive oil and water extracts of propolis are more reliable than propylene glycol extract in pregnant and infant rats.

Antiviral, Antibacterial, Antifungal, and Antiparasitic Properties of Propolis: A Review

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.

Analysis of antimicrobial activity of Karnataka propolis against oral pathogens – An in vitro study

Background:

Propolis, a natural antibiotic, which is in high demand in dentistry is a resinous substance. The main ingredient of propolis that is required for antibiotic effect is flavonoids and phenolic acids. Although propolis is a promising option for the control of oral microbes with lower related hazards and a good immunomodulator effect, its composition differs considerably depending on its botanical origin, the site and the season of collection. This original research aims to find the chemical composition and minimum inhibitory concentration (MIC) of propolis procured from different places of Karnataka state. The results would help the dentist and the pharmacist to select the best propolis to use as antibiotics in treating oral disease.

Materials and Methods:

Propolis sample from 5 different locations of Karnataka was procured from single apiary in Bangalore. Extraction of propolis using two different extracting solvents was carried out. The total phenolic content, total flavonoid content and MIC of each sample were analyzed.

Results:

Water extract propolis of Sullia and Hubli was highly active against tested organism with the MIC <0.312; alcohol extract of Sullia, Hubli and Chitradurga was moderately active with the MIC between 0.312 and 5 mg/ml. Vijayapura and Bagalkot were least active with the MIC >5 mg/ml at tested concentration.

Conclusion:

Propolis procured from different locations of Karnataka can be used as an antimicrobial agent with varying concentrations. However, when propolis is procured for therapeutic purpose, then it needs to be tested for its chemical composition before being utilized.

Propolis nanoparticles modulate the inflammatory and apoptotic pathways in carbon tetrachloride-induced liver fibrosis and nephropathy in rats

This study assessed the use of emulsion-produced propolis nanoparticles for treating carbon tetrachloride (CCl4 )-induced liver fibrosis and nephropathy on albino rat model. The evaluation of hepatotoxicity, nephrotoxicity, and the treatment outcomes involved biochemical investigations of blood samples as well as molecular analysis, and histopathological assessment for liver and kidney tissue samples. CCl4 treatment caused elevated biochemical indicators of hepatotoxic and nephrotoxic effects as detected by liver and kidney functions tests, which improved gradually with propolis nanoparticles treatment. The molecular studies showed an increase in transforming growth factor β (TGF-β), Nephrin, and Caspase-9, while Bcl-2 levels dropped in both liver and kidney tissue samples; such changes were normalized after treatment. The histological findings confirm both biochemical and molecular studies. Our results indicated that propolis nanoparticles had an anti-inflammatory effect as proved by decreased expression of TGF-β in liver tissue and Nephrin in kidney tissue. The propolis nanoparticles showed an anti-apoptotic effect on liver and kidney tissue increasing the expression of Bcl-2 and decreasing the expression of Caspase-9.

Propolis as a novel antibacterial agent

Propolis (bee glue) is a bee glue, sticky resinous material released from various plant sources such as bud exudates, flowers, and leaves modified by bee secretions and wax propolis is composed of resins, waxes, polyphenols, polysaccharides, volatile materials, and secondary metabolites that are responsible for various bioactivity such as antibacterial, anti-angiogenic, antiulcer, anti-inflammatory, antioxidant, and anti-viral activities. The physico-chemical characteristics and the natural properties of various kinds of propolis have been studied for the past decade. Novel active anti-microbial compounds have been identified in propolis. Those compounds positively modulated the antimicrobial resistance of multidrug resistant bacteria. Published research has indicated that propolis and its derivatives has many natural antimicrobial compounds with a broad spectrum against different types of bacteria and that it enhanced the efficacy of conventional antibiotics. Besides, the combination of propolis with other compounds such as honey has been studied whereby, such combinations have a synergistic effect against bacterial strains such as Escherichia coli and Staphylococcus aureus. The activity of propolis is very much dependent on seasonal and regional factors, and Middle Eastern propolis have shown best antibacterial efficacy. Propolis and its main flavonoids ingredients should not be overlooked and should be evaluated in clinical trials to better elucidate their potential application in various fields of medicine. Clinical antibacterial potential and its use in new drugs of biotechnological products should be conducted. This review aims at highlighting some of the recent scientific findings associated with the antibacterial properties of propolis and its components.

Antileishmanial Potential of Propolis Essential Oil and Its Synergistic Combination With Amphotericin B

The antileishmanial activity of Tunisian propolis essential oil (EO) and its combination with amphotericin B was investigated against 2 local clinical strains of Leishmania: Leishmania major and Leishmania infantum. The cytotoxic potential of this EO was evaluated against macrophage Raw264.7. Combination of propolis EO and amphotericin B was investigated using the checkerboard method. The propolis sample was collected from the region of Beni Khalled, a Tunisian city located west of Cape Bon (Nabeul). Its location is particular since it is near to sea with a steppe climate and the predominance of citrus trees. The EO was obtained by Clevenger-type apparatus. Its chemical composition was identified using gas chromatography with flame ionization detector and gas chromatography-mass spectrometry analysis. Our results demonstrate that Tunisian propolis EO exhibit good antileishmanial activity against L. major and L. infantum promastigotes (IC50 = 5.29 ± 0.31 and 3.67 ± 0.52 µg/mL, respectively) and amastigotes (IC50 = 7.38 ± 0.45 and 4.96 ± 0.24 µg/mL, respectively). Moreover, it reduced significantly the parasite proliferation on a dose-dependent response (95%) with low cytotoxicity (selectivity index = 16.18 and 23.33, respectively). Its combination with amphotericin B showed a synergistic potential (fractional inhibitory concentration = 0.37). Interestingly, the data suggest that propolis EO was involved in macrophage activation by hyperproduction of NO. A total of 51 compounds were identified in the propolis EO. The major compound identified was α-pinene (36.7% ± 2.36%) followed by α-cedrol (6.7% ± 0.10%), totarol (6.6% ± 0.09%), and dehydroabietane (5.2% ± 0.10%). Our findings suggest that Tunisian propolis might constitute a promising source for antileishmanial molecules.

Bioengineered keratocyte spheroids fabricated on chitosan coatings enhance tissue repair in a rabbit corneal stromal defect model

Cultivated cell spheroid transplantation is widely studied as a means of facilitating tissue regeneration. Chitosan biomaterial has been shown to promote keratocyte aggregation and multicellular spheroid formation. This study provides further evidence on application of bioengineered keratocyte spheroids for corneal stromal tissue engineering. In an allogeneic rabbit model of stromal destruction caused by bacterial keratitis, the corneas were intrastromally injected with isolated keratocyte suspensions or aggregated spheroid grafts at same cell number. Results of clinical observations and histological examinations on postoperative day 14 showed that when an antibiotic eye drop is only medication for inhibiting bacterial growth, permanent damage to stroma occurs, leading to disorganization of collagen lamellae and tissue structure as well as loss of corneal transparency and visual function. Intrastromal grafting of keratocytes provided additional benefits to overcome drawbacks of limited disease treatment performance associated with topically applied antibiotics. In particular, as compared to their cell suspension counterparts, bioengineered keratocyte spheroids had higher ability to preserve cellular phenotype, secrete collagen matrix, and enhance graft retention, suggesting excellent repair capability for managing stromal tissue defect and alleviating corneal haze/oedema. In summary, the findings emphasize the role of keratocyte configuration (i.e., two-dimensional monolayer or three-dimensional spheroid) in determining therapeutic potency of cellular allografts for stromal tissue reconstruction. Transplantation of keratocyte spheroids cultured on chitosan substrates may represent a promising strategy for corneal stromal repair.

Super-Cationic Carbon Quantum Dots Synthesized from Spermidine as an Eye Drop Formulation for Topical Treatment of Bacterial Keratitis

We have developed a one-step method to synthesize carbon quantum dots (CQD_PAs) from biogenic polyamines (PAs) as an antibacterial agent for topical treatment of bacterial keratitis (BK). CQDs synthesized by direct pyrolysis of spermidine (Spd) powder through a simple dry heating treatment exhibit a solubility and yield much higher than those from putrescine and spermine. We demonstrate that CQDs obtained from Spds (CQD_Spds) possess effective antibacterial activities against non-multidrug-resistant Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enterica serovar Enteritidis bacteria and also against the multidrug-resistant bacteria, methicillin-resistant S. aureus. The minimal inhibitory concentration (MIC) of CQD_Spds is ∼2500-fold lower than that of spermidine alone, demonstrating their strong antibacterial capabilities. Investigation of the possible mechanisms behind the antibacterial activities of the as-synthesized CQD_Spds indicates that the super-cationic CQD_Spds with small size (diameter ca. 6 nm) and highly positive charge (ζ-potential ca. +45 mV) cause severe disruption of the bacterial membrane. In vitro cytotoxicity, hemolysis, hemagglutination, genotoxicity, and oxidative stress and in vivo morphologic and physiologic cornea change evaluations show the good biocompatibility of CQD_Spds. Furthermore, topical ocular administration of CQD_Spds can induce the opening of the tight junction of corneal epithelial cells, thereby leading to great antibacterial treatment of S. aureus-induced BK in rabbits. Our results suggest that CQD_Spds are a promising antibacterial candidate for clinical applications in treating eye-related bacterial infections and even persistent bacteria-induced infections.

Traditional Therapies for Skin Wound Healing

Significance: The regeneration of healthy and functional skin remains a huge challenge due to its multilayer structure and the presence of different cell types within the extracellular matrix in an organized way. Despite recent advances in wound care products, traditional therapies based on natural origin compounds, such as plant extracts, honey, and larvae, are interesting alternatives. These therapies offer new possibilities for the treatment of skin diseases, enhancing the access to the healthcare, and allowing overcoming some limitations associated to the modern products and therapies, such as the high costs, the long manufacturing times, and the increase in the bacterial resistance. This article gives a general overview about the recent advances in traditional therapies for skin wound healing, focusing on the therapeutic activity, action mechanisms, and clinical trials of the most commonly used natural compounds. New insights in the combination of traditional products with modern treatments and future challenges in the field are also highlighted. Recent Advances: Natural compounds have been used in skin wound care for many years due to their therapeutic activities, including anti-inflammatory, antimicrobial, and cell-stimulating properties. The clinical efficacy of these compounds has been investigated through in vitro and in vivo trials using both animal models and humans. Besides the important progress regarding the development of novel extraction methods, purification procedures, quality control assessment, and treatment protocols, the exact mechanisms of action, side effects, and safety of these compounds need further research. Critical Issues: The repair of skin lesions is one of the most complex biological processes in humans, occurring throughout an orchestrated cascade of overlapping biochemical and cellular events. To stimulate the regeneration process and prevent the wound to fail the healing, traditional therapies and natural products have been used with promising results. Although these products are in general less expensive than the modern treatments, they can be sensitive to the geographic location and season, and exhibit batch-to-batch variation, which can lead to unexpected allergic reactions, side effects, and contradictory clinical results. Future Directions: The scientific evidence for the use of traditional therapies in wound healing indicates beneficial effects in the treatment of different lesions. However, specific challenges remain unsolved. To extend the efficacy and the usage of natural substances in wound care, multidisciplinary efforts are necessary to prove the safety of these products, investigate their side effects, and develop standard controlled trials. The development of good manufacturing practices and regulatory legislation also assume a pivotal role in order to improve the use of traditional therapies by the clinicians and to promote their integration into the national health system. Current trends move to the development of innovative wound care treatments, combining the use of traditional healing agents and modern products/practices, such as nanofibers containing silver nanoparticles, Aloe vera loaded into alginate hydrogels, propolis into dressing films, and hydrogel sheets containing honey.

Antiviral Activity of Hatay Propolis Against Replication of Herpes Simplex Virus Type 1 and Type 2

Background

Propolis is a bee product widely used in folk medicine and possessing many pharmacological properties. In this study we aimed to investigate: i) the antiviral activities of Hatay propolis samples against HSV-1 and HSV-2 in HEp-2 cell line, and ii) the presence of the synergistic effects of propolis with acyclovir against these viruses.

Material/Methods

All experiments were carried out in HEp-2 cell cultures. Proliferation assays were performed in 24-well flat bottom microplates. We inoculated 1×10⁵ cells per ml and RPMI 1640 medium with 10% fetal calf serum into each well. Studies to determine cytotoxic effect were performed. To investigate the presence of antiviral activity of propolis samples, different concentrations of propolis (3200, 1600, 800, 400, 200, 100, 75, 50, and 25 μg/mL) were added into the culture medium. The amplifications of HSV-1 and HSV-2 DNA were performed by real-time PCR method. Acyclovir (Sigma, USA) was chosen as a positive control. Cell morphology was evaluated by scanning electron microscopy (SEM).

Results

The replication of HSV-1 and HSV-2 was significantly suppressed in the presence of 25, 50, and 100 μg/mL of Hatay propolis. We found that propolis began to inhibit HSV-1 replication after 24 h of incubation and propolis activity against HSV-2 was found to start at 48 h following incubation. The activity of propolis against both HSV-1 and HSV-2 was confirmed by a significant decrease in the number of viral copies.

Conclusions

We determined that Hatay propolis samples have important antiviral effects compared with acyclovir. In particular, the synergy produced by antiviral activity of propolis and acyclovir combined had a stronger effect against HSV-1 and HSV-2 than acyclovir alone.

Susceptibility of Staphylococcus aureus clinical isolates to propolis extract alone or in combination with antimicrobial drugs

The objective of this study was to assess in vitro the antimicrobial activity of ethanolic extract of Polish propolis (EEPP) against methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates. The combined effect of EEPP and 10 selected antistaphylococcal drugs on S. aureus clinical cultures was also investigated. EEPP composition was analyzed by a High Performance Liquid Chromatography (HPLC) method. The flavonoid compounds identified in Polish Propolis included flavones, flavonones, flavonolols, flavonols and phenolic acids. EEPP displayed varying effectiveness against twelve S. aureus strains, with minimal inhibitory concentration (MIC) within the range from 0.39 to 0.78 mg/mL, determined by broth microdilution method. The average MIC was 0.54 ± 0.22 mg/mL, while calculated MIC₅₀ and MIC₉₀ were 0.39 mg/mL and 0.78 mg/mL, respectively. The minimum bactericidal concentration (MBC) of the EEPP ranged from 0.78 to 3.13 mg/mL. The in vitro combined effect of EEPP and 10 antibacterial drugs was investigated using disk diffusion method-based assay. Addition of EEPP to cefoxitin (FOX), clindamycin (DA), tetracycline (TE), tobramycin (TOB), linezolid (LIN), trimethoprim+sulfamethoxazole (SXT), penicillin (P), erythromycin (E) regimen, yielded stronger, cumulative antimicrobial effect, against all tested S. aureus strains than EEPP and chemotherapeutics alone. In the case of ciprofloxacin (CIP) and chloramphenicol (C) no synergism with EEPP was observed.

In Vitro Antimicrobial Activity of Ethanolic Extract of Polish Propolis against Biofilm Forming Staphylococcus epidermidis Strains

The aim of the presented study was to examine the antimicrobial activity of ethanol extract of Polish propolis (EEPP) against biofilm-forming CoNS strains in vitro. Our results revealed that EEPP displayed varying degrees of activity against CoNS with MIC values ranging from 1.56 to 0.78 mg/mL. The average MIC was 1.13 ± 0.39 mg/mL while calculated MIC₅₀ and MIC₉₀ values were 0.78 mg/mL and 1.56 mg/mL, respectively. The biofilm formation ability by all tested S. epidermidis strains was inhibited at EEPP concentrations ranging from 0.39 to 1.56 mg/mL. The degree of reduction of AlamarBlue was directly associated with the proliferation of S. epidermidis strains. The increased proliferation of S. epidermidis strains was observed after 12 and 24 hours of incubation in the presence of EEPP concentrations ranging from 0.025 to 0.39 mg/mL. These results suggest that antimicrobial activities of EEPP against S. epidermidis expressed as the reduction of bacterial growth, reduction of biofilm formation ability, and the intensity of proliferation were significantly affected by incubation time and EEPP concentration used as well as the interactions between these factors.

Propolis: is there a potential for the development of new drugs?

INTRODUCTION

Propolis has plenty of biological and pharmacological properties and its mechanisms of action have been widely investigated in the last years, using different experimental models in vitro and in vivo. Researchers have been interested in the investigation of isolated compounds responsible for propolis action; however, there is lack of clinical research on the effects of propolis.

STRATEGY AND OBJECTIVES

Since propolis-containing products have been marketed and humans have used propolis for different purposes, the goal of this review is to discuss the potential of propolis for the development of new drugs, by comparing data from the literature that suggest candidate areas for the establishment of drugs against tumors, infections, allergy, diabetes, ulcers and with immunomodulatory action.

CONCLUSIONS

The efficacy of propolis in different protocols in vitro and in vivo suggests its therapeutic properties, but before establishing a strategy using this bee product, it is necessary to study: (a) the chemical nature of the propolis sample. (b) Propolis efficacy should be compared to well-established parameters, e.g. positive or negative controls in the experiments. Moreover, possible interactions between propolis and other medicines should be investigated in humans as well. (c) Clinical investigation is needed to evaluate propolis potential in patients or healthy individuals, to understand under which conditions propolis may promote health. Data point out the importance of this research field not only for the readers and researchers in the scientific community waiting for further clarification on the potential of propolis but also for the pharmaceutical industry that looks for new drugs.

Animal models of bacterial keratitis

Bacterial keratitis is a disease of the cornea characterized by pain, redness, inflammation, and opacity. Common causes of this disease are Pseudomonas aeruginosa and Staphylococcus aureus. Animal models of keratitis have been used to elucidate both the bacterial factors and the host inflammatory response involved in the disease. Reviewed herein are animal models of bacterial keratitis and some of the key findings in the last several decades.

Angiostatic effects of Brazilian green propolis and its chemical constituents

Propolis, a resinous substance collected by honeybees from various plant sources, has several pharmacological actions, such as anti-tumor and anti-inflammatory effects. The aim of this study was to evaluate the anti-angiogenic effects of a water extract of Brazilian green propolis (WEP) and its constituents, caffeoylquinic acid derivatives, against angiogenic processes in human umbilical vein endothelial cells (HUVECs) in vitro. We also examined the anti-angiogenic effects of WEP against retinal neovascularization in a murine oxygen-induced retinopathy model in vivo. WEP and its constituents significantly suppressed vascular endothelial growth factor (VEGF)-induced HUVEC proliferation, migration, and tube formation in vitro. WEP and its caffeoylquinic acid derivatives suppressed VEGF-stimulated phosphorylation of mitogen-activated protein kinase in HUVECs (versus VEGF alone). Moreover, WEP (300 mg/kg/day, subcutaneously for 5 days) significantly suppressed retinal neovascularization in the murine oxygen-induced retinopathy model. These data indicate that (i) WEP has angiostatic effects against angiogenic processes in vitro and in an in vivo model of murine oxygen-induced retinopathy and (ii) the inhibitory effects of WEP against in vitro angiogenesis are chiefly derived from its caffeoylquinic acid derivatives. Judging from these findings, WEP and its caffeoylquinic acid derivatives may represent candidates for preventive or therapeutic agents against diseases caused by angiogenesis.

The protective role of topical propolis on experimental keratitis via nitric oxide levels in rabbits

The aim of this study was to investigate antioxidant, anti-inflammatory, and antibacterial properties of propolis in the treatment of experimental Staphylococcus aureus keratitis. Twenty young New Zealand white rabbits were used in this experiment. Staphylococcus aureus were given by intrastromal injection to 16 rabbits and 4 rabbits were used as control group (Group 1). Group 2 was treated with phosphate-buffered solution drops; Group 3 was administered ethanolic extract of propolis drops; Group 4 received topical ciprofloxacin drops; Group 5 was treated with topical ciprofloxacin drops along with ethanolic extract of propolis drops. The eyes were examined by slit lamp to assess corneal opacity. And then, corneas were removed to determine nitric oxide (NO) levels and count bacteria. Corneas were also evaluated histologically. Corneal NO concentration in group 5, treated with a combination of propolis and ciprofloxacin was determined significantly lower (10.0+/- 1.8 micromol/g wet tissue) than in Group 4, treated with ciprofloxacin (24.0+/- 3.1 micromol/g wet tissue), from Group 3, treated with propolis (15.6+/- 1.8 micromol/g wet tissue), and treated with PBS (44.7+/- 7.8 micromol/g wet tissue). There were significantly fewer bacteria in eyes that received propolis plus ciprofloxacin than in eyes treated with ciprofloxacin (p = 0.0001) or propolis (p = 0.0001) or eyes treated with PBS (p = 0.0001). The light microscopic examination revealed that the control group showed normal corneal morphology. In the nontreated group, sections of the stromal infiltration revealed the presence of inflammatory cells, which were diffusely distributed (p < 0.05). Administrations of ciprofloxacin plus propolis resulted in a significantly reduced histological damage with fewer bacterial inoculation of the corneal stroma in comparison with the other groups (p < 0.05). Based on these findings, we suggest that ethanolic extract of propolis has antioxidant, anti-inflammatory, and antibacterial properties for S. aureus keratitis in rabbits.

In vitro antileishmanial activity of Adana propolis samples on Leishmania tropica: a preliminary study

Propolis (bee glue) is a natural resinous hive product, collected from various plant sources. It has attracted much attention as a useful substance applied in medicine due to its pharmacological activities. It was aimed to investigate the in vitro effects of an ethanolic extract of Adana propolis samples on the growth of Leishmania tropica. Parasite cells were treated with five concentrations (25, 50, 100, 50, 500, and 750 microg/ml) of the propolis. The number of promastigotes in each concentration was calculated using a hemocytometer slide at 24, 48, and 72 h after being harvested. In the experiments, it was determined that the concentrations up to 100 mug/ml of the propolis did not exhibit antileishmanial activity against the parasites cells. At these concentrations, there was no changes in terms of morphologically. In addition, there was no statistically significant difference in terms of cell count between control and these three groups (p > 0.05). However, in culture media containing the propolis samples at 250, 500, and 750-microg/ml concentrations, statistically significant differences in cell counts were observed, as compared to the control group (p < 0.05). Our results demonstrate that ethanolic extracts of Adana propolis samples reduce the proliferation of L. tropica parasites significantly.

Antibacterial activity of propolis against MRSA and synergism with topical mupirocin

OBJECTIVES

The aim of the present study was to investigate the activity of the propolis and its combinations with mupirocin against methicillin-resistant Staphylococcus aureus (MRSA) in nasal carriage.

METHODS

This study was carried out between June and August 2005. To infect nares of the rabbits, MRSA (ATCC 33591) strain was used. Minimum inhibitory concentration was determined according to National Committee for Clinical Laboratory Standards. Each inoculum was prepared in the same medium at a density adjusted to a 0.5 McFarland turbidity standard (10(5) colony-forming units [cfu]/mL) and diluted 1:100 for the broth microdilution procedure. Ten microliters (10 microL) (10(5) cfu/mL) of the bacterial suspension containing approximately 1000 cfu of MRSA was administered with sterile microsyringe through both nostrils of each rabbit. Ninety-six (96) hours after inoculation, the presence of infection was confirmed by using bacterial cultures. Twenty-six young New Zealand rabbits were randomly divided into 4 groups. Each treatment group (1, 2, and 3) included 7 rabbits and control group (group 4) included 5 rabbits. Group 1 was treated with topical mupirocin + ethanolic extract of propolis drops, group 2 received topical mupirocin, group 3 was administered ethanolic extract of propolis drops, and the control group (group 4) was only treated with phosphate-buffered solution drops for 7 days. At the end of study, nasal cultures and smears were obtained for bacterial count and cytologic examination.

RESULTS

The colony numbers of bacteria in group 1 were determined to be significantly lower than in group 2 (p = 0.0001), group 3 (p = 0.0001), and group 4 (p = 0.0001). The mean bacterial cell counts of groups 1-4 were 360.2 +/- 52.4 cfu/mL, 4120.6 +/- 860.4 cfu/mL, 5980.8 +/- 1240.6 cfu/mL, and 11500.0 +/- 2568.4 cfu/mL, respectively. Mupirocin + propolis administration (group 1) resulted in a significant reduction in the polymorphonuclear leukocyte (PMNL) count in the mucous membranes of rabbits compared with the other treatment groups (p < 0.05).

CONCLUSIONS

Propolis addition to mupirocin regimen was found to result in more profound reduction in bacterial cell count and inflammatory response compared with the rest of the treatment modalities.

The effect of propolis in experimental Acanthamoeba keratitis

PURPOSE

To examine the effect of propolis in a rat model of Acanthamoeba keratitis and to determine its in vitro cytotoxicity in cultured corneal epithelial cells.

METHODS

Eighteen Wistar albino rats were used. Cultured corneal epithelial cells obtained from two healthy rats for in vitro cytotoxicity of propolis. Corneal stromal inoculation was performed in 16 rats with amoebic culture containing 1 x 10(6) amoeba/mL. Rats with Acanthamoeba keratitis 5 days later after the inoculation were divided randomly into four groups, and eight eyes of each group were treated with study drugs. The propolis, chlorhexidine (CHX), propolis plus CHX and control eyes were treated with topical propolis, 0.002% CHX, propolis plus 0.002% CHX and lubricant eye drops, respectively. The study drugs were instilled every one hour for 10 days. All eyes were examined and keratitis graded by slit-lamp biomicroscopy on days 2, 5 and 10 during the administration of the study drugs. After the completion of keratitis grading, all the 16 rats were humanely killed and their corneas were excised and used for Acanthamoeba culture to evaluate presence of Acanthamoeba growth after treatment 14 days later.

RESULTS

Concentrations of propolis higher than 7.81 mg/mL cause damage to corneal epithelial cells in the experiment of in vitro cytotoxicity of propolis on corneal epithelial cells. The keratitis grade on day 2 in the CHX eyes was significantly lower than that in the control eyes (P < 0.05). The keratitis grades on days 5 and 10 in the propolis, CHX and propolis plus CHX eyes were significantly lower compared with those on days 5 and 10 in the control eyes (P < 0.05). In the propolis eyes, the keratitis grade on day 5 was significantly lower than that on day 2 (P < 0.05), and it was significantly lower on day 10 compared with that on day 5 (P < 0.05). In the CHX and propolis plus CHX eyes, the keratitis grade on day 10 was significantly lower compared with that on days 2 and 5 (P < 0.05). In the control eyes, there was no significant difference in the keratitis grades on days 2, 5 and 10 (P > 0.05). The culture positivity at Acanthamoeba growth after treatment experiment in the propolis, CHX and propolis plus CHX eyes was significantly lower than that in the control eyes (P < 0.05).

CONCLUSIONS

We suggest that propolis had amoebicidal properties in this rat model of Acanthamoeba keratitis. Further investigations to evaluate the antimicrobial activity of the individual fractions of the resin could yield more information about its mechanism of action in treating this disease.

Survival and integration of tissue-engineered corneal stroma in a model of corneal ulcer

Tissue-engineered replacement of diseased or damaged tissue has become a reality for some types of tissue, such as skin and cartilage. Tissue-engineered corneal stroma represents a promising concept to overcome the limitations of cornea replacement with allograft. In this study, porcine cornea was decellularized by a series of extraction methods, and the in vivo biocompatibility of the scaffold was measured subcutaneously in rabbits (n = 8). These were not acutely rejected and no abscesses were observed by hematoxylin and eosin staining at the 8th week, indicating that the scaffolds had good biocompatibility. To investigate the potential value of clinical applications, rabbit stromal keratocytes were implanted onto decellularized scaffolds to fabricate tissue-engineered corneal stroma. Allograft, tissue-engineered corneal stroma, or scaffolds were implanted into a model of corneal ulcer. The survival and reconstruction of corneal transplantation were morphologically evaluated by light and electron microscopy until the 32nd week after implantation. Experiments involving transplantation indicated that the epithelial and stromal defect healed quickly, with improvement in corneal clarity. The integration of the graft was accompanied by neurite ingrowth from the host tissue. By 16 weeks after transplantation, the cornea had gradually regained an intact state similar to that of normal cornea. Our results demonstrate that the tissue-engineered corneal stroma with allogenetic cells is a promising therapeutic method for corneal injury.