Jokūbaitė, Monika

Propolis is a widely studied natural raw material, the composition of which varies depending on the plant origin, harvest season, geographical area, climate and bee species. This large variety of chemical composition limits the use of propolis extracts in the pharmaceutical industry, which makes it difficult to ensure standardization of the raw material. One of the challenges that limit the modeling of oral pharmaceutical forms with propolis extract is the limited solubility and bioavailability of active compounds. Solid dispersion technology is commonly used in the production of oral capsules. The aim of this study is to evaluate the influence of different materials (HPMC, poloxamer and β-cyclodextrin) on the dissolution kinetics of phenolic compounds of propolis dry extract contained in capsules and their antioxidant activity in vitro. Analysis of the selected formulations showed that the major phenolic compounds detected in the propolis extract were also present in the dissolution medium samples. The auxiliary polymeric materials selected for the capsules formed a prerequisite for the dissolution kinetics profile. The addition of poloxamer and cyclodextrin increased the solubility and dissolution kinetics of hydrophobic propolis compounds in the test media. The addition of HPMC prolonged the dissolution kinetics of propolis active compounds. The antioxidant activity of the tested samples depends on the concentration of active compounds in the receptor medium by both the ABTS and DPPH methods.

p-coumaric acid is a natural phenolic compound with antioxidant activity, but its poor solubility and low bioavailability limit its practical use in oral formulations. The aim of this study is to evaluate how different polymers affect the dissolution and antioxidant properties of p-coumaric acid when incorporated into capsules and gels. Nine capsule compositions were prepared using poloxamer 407 (C1 group), sodium carboxymethyl cellulose (C2 group), chitosan (C3 group) and 5 hydrogels (G group) with the same polymers. The results indicate that p-coumaric acid is poorly soluble in aqueous solvents. The selected polymers modified the solubility of p-coumaric acid. The best solubility of p-coumaric acid was observed in mixtures containing 14.3% Poloxamer 407 (P407). The results showed that the polymers significantly affected the release kinetics of p-coumaric acid from the modeled capsules and gels. It was observed that capsules containing 14.3% P407 and gels with 14% P407 exhibited the best dissolution kinetics of p-coumaric acid. Antioxidant activity was strongest in formulations that released more p-coumaric acid. The results of this study confirm that the type and amount of excipients significantly affect the quality of capsules and gels. p-coumaric acid has the potential to be used in food supplements as a natural antioxidant, but further research is needed to improve its bioavailability and ensure safety.

Skin infections are common in veterinary practice and are often treated with topical agents. Superficial pyoderma (superficial bacterial folliculitis) is a common cause of skin disease in dogs and a reason for treatment, most caused by Staphylococcus spp. strains. The frequent use of antibiotics contributes to the emergence of resistant bacterial strains, making antimicrobial resistance (AMR) one of the most important threats to human and animal health. For this reason, active natural compounds are increasingly being explored as alternative therapies. To contribute to the development of effective treatments for bacterial infectious diseases, researchers are looking for new antimicrobial agents. Topical drug action has many advantages as it avoids systemic reactions and ensures that the active substance reaches the site of the lesion directly. This study aimed to develop gelled dosage forms with propolis extract and to evaluate their antibacterial activity and the release of the active substances. Hydrogels, oleogels, and bigels enriched with eutectic propolis extract were produced. Deep eutectic solvents (DESs) were chosen as an effective tool to extract the active compounds of propolis and to improve their penetration into the skin. The pH values of the semi-solid pharmaceutical forms tested ranged from 3.3 to 6.4. Using modified Franz-type diffusion cells, the release of phenolic compounds from gels, oleogels, and bigels was assessed and quantified spectrophotometrically using the Folin–Ciocalteu method. The highest amount of active compounds was released from the hydrogels, while the lowest amount was released from the castor oil-based oleogel. The study used clinical and reference strains of bacteria. The antimicrobial activity of the gelled dosage forms with propolis extract was tested against six pathogenic bacterial species (S. aureus, S. agalactiae, B. cereus, E. faecalis, E. coli, Ps. aeruginosa) and one pathogenic fungus (C. albicans). The study’s results suggest that the propolis extract obtained by DES has significant antibacterial activity and is a promising component in skin formulations for the treatment of bacterial infections.

Caffeic acid, a phenolic compound with antioxidant and antimicrobial properties, shows promise in the dermatological field. The research aimed to incorporate caffeic acid into hydrophilic gels based on poloxamer 407, carbomer 980, and their mixture in order to enhance its biological activity. Different gel formulations were prepared using different concentrations of these polymers to optimize caffeic acid release characteristics. The results showed that increasing the concentration of polymeric materials increased the viscosity and slowed down the release of caffeic acid. The antioxidant and antimicrobial activities of the gels were assessed. The results confirmed the potential of hydrophilic gels as delivery systems for caffeic acid, with formulations showing antimicrobial activity against Gram-positive Staphylococcus aureus bacteria and antifungal activity against Candida albicans fungus. This study provides a perception of the development of new semi-solid caffeic acid-based formulations for therapeutic and cosmetic applications.

Antimicrobial resistance (AMR) is one of the biggest threats to human and animal health. Efforts to combat AMR include the introduction of antimicrobial drugs as alternative treatment options. To contribute to an effective plan for the treatment of infectious diseases caused by bacteria, the development of new antimicrobial agents is increasingly being explored. Propolis has garnered significant attention from both scientists and industry due to its extensive spectrum of biological activity. The growing interest in polyphenols of natural origin and their plant sources further encourages the investigation of their chemical composition and biological effects. Propolis serves as a rich source of phenolic compounds. Baltic region propolis, classified as poplar-type propolis, was selected for this study, and extracts were prepared using raw propolis materials from various Baltic countries. The production of liquid extracts utilized a combination of 70 percent ethanol, a mixture of water and poloxamer P407, and DES (deep eutectic solvent). The research aims to produce liquid propolis extracts using different solvents and to assess their chemical composition, antioxidant, and antimicrobial activity against different veterinary pathogens. Antioxidant activity was evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl), revealing antioxidant activity in all extracts, with results correlating with the total phenolic compound content. It was found that p-coumaric acid predominated in the studied propolis extracts (in ethanol extracts 1155.90–1506.65 mg/g, in DES extracts 321.13–954.76 mg/g, and in polymeric extracts 5.34–30.80 mg/g), with smaller amounts of ferulic acid and vanillin detected. Clinical and reference bacterial strains were collected from the Lithuanian University of Health Sciences, the Academy of Veterinary Medicine, and the Institute of Microbiology and Virology. To effectively treat bacterial infections, the antimicrobial activity of propolis extracts was tested against six pathogenic bacterial species and one pathogenic fungus (S. aureus, S. agalactiae, B. cereus, E. faecalis, E. coli, P. aeruginosa, and C. albicans). Antimicrobial activity studies demonstrated that DES propolis extracts exhibited stronger antimicrobial activity compared to ethanolic propolis extracts. The minimum inhibitory concentration (MIC) values of DES propolis extracts against the tested strains ranged between 50 and 1000 μg/mL. Considering the study results, it can be concluded that propolis from the Baltic region is abundant in phenolic compounds exhibiting antioxidant and antibacterial activities.

Pastaraisiais metais vis plačiau nagrinėjamos fenolio rūgštys dėl jų daromo plataus biologinio poveikio. Dauguma fenolio rūgščių pasižymi prastu tirpumu, o tai apriboja jų panaudojimą farmacijos pramonėje. Mokslininkai sprendžia p-kumaro rūgšties tirpumo problemas ir siekia pritaikyti šiuos junginius geriamosioms farmacinėms formoms. Todėl aktualu sumodeliuoti kapsules su p-kumaro rūgštimi ir įvertinti pagalbinių medžiagų daromą įtaką jos tirpimo kinetikai. Suirimo ir tirpimo testai suteikia informacijos apie pagalbinių medžiagų įtaką kapsulių kokybei. Tyrimo tikslas yra sumodeliuoti kokybiškas kapsules su p-kumaro rūgštimi ir įvertinti jų kokybę. Silicifikuotos mikrokristalinės celiuliozės kiekis (60 proc.) kapsulėje pagerina p-kumaro rūgšties išsiskyrimą ir tirpumą iš kapsulių. 25 mg poloksamero 407 kiekis 175 mg kapsulėje pagerino p-kumaro rūgšties kinetiką. Natrio karboksimetilceliuliozė ir chitozanas yra polimerai, kurie prailgina p-kumaro rūgšties išsiskyrimą iš kapsulių.

In situ poloxamer-based gels are increasingly being explored as ocular drug delivery carriers to extend the release of active substances, thereby enhancing bioavailability. The objective of this study was to develop thermally stable in situ gels incorporating balsam poplar bud extract, propolis extract, and p-coumaric acid solution and to evaluate the physicochemical parameters of these gelified eye drops. This research assessed the compatibility of poloxamer-based eye drops with active components, their physicochemical properties, stability post-sterilization and during storage, and the release profiles of the active compounds. Fifteen eye drop formulations were prepared and categorized into three groups based on active components. One of the active components was propolis extract. As an alternative to propolis, eye drops containing the plant precursor, balsam poplar bud extract, were developed. The third group’s active component was p-coumaric acid, a dominant phenolic acid in propolis and balsam poplar bud extracts. The study reported phenolic contents of 76.63 CAE mg/g for propolis and 83.25 CAE mg/g for balsam poplar bud aqueous extracts, with balsam poplar bud extracts showing higher SPF values (14.0) compared to propolis (12.7), while p-coumaric acid solution exhibited the highest SPF values (25.5). All eye drops were transparent, with pH values meeting the requirements for ocular drops. Formulations containing 8–10% poloxamer 407 met the criteria for in situ gels. All formulations remained stable for 90 days. Conclusion: The study results indicate that the formulated gels possess suitable physicochemical properties, are resistant to applied autoclaving conditions, and exhibit an extended release of active compounds with an increase in poloxamer content.

P-coumaric (p-CA) acid is a hydroxyl derivative of cinnamic acid. Currently, p-coumaric acid is widely studied by scientists for its antioxidant, antibacterial and anti-inflammatory properties. This study aimed to model capsules with p-coumaric acid using solubility-enhancing excipients. During the research, the following methods were applied: capsule mass uniformity, disintegration test and dissolution test. UV/Vis spectrophotometry was used as a method to determine the amount of p-coumaric acid. A statistical analysis of the results was performed. The results of the study showed that the addition of poloxamer 407 in the encapsulable mixture affects the solubility of p-CA: when the capsule contains up to 25% of poloxamer, the solubility of p-coumaric acid is improved; when poloxamer concentration is greater than 25%, the solubility of p-CA decreases. The solubility of p-coumaric acid in the capsule depends on the amount of poloxamer.

Balsam poplar buds have been used for wound healing and treating irritated skin in traditional medicine. Balsam poplar buds extracts exhibit anti-inflammatory, antioxidant, and antimicrobial effects. In recent years, scientific research has begun to validate some of these traditional uses, leading to an increased interest in balsam poplar buds as a potential source of natural remedies in modern medicine. The study aims to simulate semi-solid pharmaceutical forms with balsam poplar buds extract and evaluate their quality through biopharmaceutical research. The active compounds identified in Lithuanian poplar buds were p-coumaric acid, cinnamic acid, caffeic acid, galangin, pinocembrin, pinobanksin, and salicin. In gels, pH values ranged from 5.85 ± 0.05 to 5.95 ± 0.07. The determined pH values of emulgels ranged from 5.13 ± 0.05 to 5.66 ± 0.15. After 6 h, the release of active compounds from gels and emulgels ranged from 47.40 ± 2.41% to 71.17 ± 3.54. p-coumaric acid dominates in the balsam poplar buds extracts. The pH values of the prepared sem-solid pharmaceutical forms are suitable for use on the skin. The viscosity of the formulations depends on the amount of gelling agent. All formulations showed antioxidant activity. It is relevant to conduct a more extensive study on the influence of the chosen carrier on the release of active compounds from semi-solid formulations with an extract of balsam poplar buds.

The aim of the thesis is to extract biologically active compounds from selected plant precursors of Lithuanian propolis, to evaluate their phytochemical composition, biological activity, and to apply them in the modeling of eye drops. This thesis presents the qualitative and quantitative spectrophotometric and instrumental analysis of the chemical composition of propolis and its plant precursors extracts , in vitro assessment of biological activity, and selection of plants extracts for further application in modeling of eye drops formulations. Studies on the biological activity, chemical composition and thermal stability using high-pressure steam sterilization of the selected aqueous and PEG400 co-solvent supplemented aqueous extracts of the plant precursors of propolis are presented. The research presented in the dissertation also includes formulation of extended-release eye drops with selected propolis plant precursor extracts, evaluating the physicochemical properties of the formulations, the release efficiency of active compounds, biological activity in vitro and thermal stability. The research results of this thesis are relevant and important in the development and formulation of topical extended-release eye drops with biologically active compounds of natural origin.