The essential oils (EOs) of (DC.) Stapf are globally recognized for their antimicrobial properties. However, their therapeutic potential is limited by their low solubility and potency. This study aimed to investigate the chemical constituents, cytotoxic activity, and antimicrobial potential of nanoemulsions based on EOs. Thirteen primary components were analyzed using gas chromatography–mass spectrometry. The major components were geraniol acetate (50.81%), citral (16.97%), β-citral (12.95%), and geranial (9.45%). Nanoemulsions containing three different concentrations (1%, 5%, and 10%) of EOs were evaluated regarding the droplet size, polydispersity index, pH, conductivity, and viscosity. The results demonstrated that nanoemulsions with spherical shapes and droplet sizes less than 143 nm were successfully formed at all tested concentrations, with average sizes of 143, 132, and 82 nm, respectively. Furthermore, all formulations were physically stable, even after undergoing stability testing. The EO of exhibited potent antibacterial activity against a broad range of foodborne pathogens, including both Gram-positive and Gram-negative bacteria, with A being the most susceptible strain. The aforementioned nanoemulsions were more effective against methicillin-resistant and . The nanoemulsions did not induce any significant cytotoxicity within the concentration range of 0.05–2 μg/mL in 24 h (p > 0.05). The cell viability consistently remained above 85%, even at the highest concentration tested. These findings suggested the strong potential of EOs and their nanoemulsion forms as natural antimicrobial agents for applications in the food and pharmaceutical industries.

The purpose of the study is to develop metronidazole (MET) containing microemulsion systems for topical application, to overcome limitations of local antibacterial treatments. For preparation of drug loaded microemulsions pseudo-phase diagram technique was applied; IPP as oil phase, Span 80 and Cremophor EL as surfactant, ethanol and propylene glycol as co-surfactant and distilled water was used as aqueous phase. Globule size ranging between 126.82.8 to 150.81.6 nm and PDI between 0.210.02 to 0.350.06 were obtained. Zeta potentials of the formulations measured as 0.480.08 – 0.680.14 mV and conductivity was between 0.50.0 and 0.60.0, implicating the formation of w/o emulsions. A UPLC method was developed and validated according to the ICH Q2 (R1) guideline, for quantification of MET, and drug content was calculated as 99.180.08 – 99.330.12%. MET release of 80.620.86% for S1MET and 62.061.08% for S2MET formulations at 24h, indicated the control over the MET release by the microemulsions. After 3. and 6. months, there were no difference in physicochemical properties of microemulsions and MET release showed similar profile; implicating the good stability of formulations.

Purpose: Centaurea lycopifolia Boiss. et Kotschy (Asteraceae) is traditionally used in folk medicine for wound healing. This study aimed to develop and pharmacologically evaluate a novel oral microemulsion containing C. lycopifolia extract, focusing on its analgesic and anti-inflammatory effects in rodent models. Methods: The extract, obtained from aerial parts of the plant, was characterized by LC-MS/MS. A microemulsion formulation was developed for oral administration. Antinociceptive activity was evaluated via hot plate (HP) and tail flick (TF) tests to assess central and spinal effects, respectively. Anti-inflammatory activity was assessed using carrageenan-induced paw edema, quantified by plethysmometry and Randall–Selitto tests. Results: LC-MS/MS analysis identified quinic acid, chlorogenic acid, and protocatechuic acid as major phytoconstituents. In both HP and TF tests, the C. lycopifolia microemulsion demonstrated significantly stronger antinociceptive effects than aspirin. Similarly, its anti-inflammatory activity was comparable to aspirin. These pharmacological effects are possibly associated with the synergistic actions of the phenolic acids present in the extract. Conclusions: The C. lycopifolia -loaded microemulsion exhibited strong in vivo analgesic and anti-inflammatory activity, supporting its potential as a phytopharmaceutical candidate for inflammatory pain. The use of both central and peripheral pain models provided a robust pharmacodynamic basis for its therapeutic potential. Overall, these findings highlight the relevance of phenolic-rich phytochemicals in oral delivery systems for inflammation-related disorders.

This study validated a high performance liquid chromatography (HPLC) method for the determination of quercetin (QE) in microemulsion (ME) based gel formulations. The analyses were performed on a C18 column (150x4.6 mm, 5 μm particle size) at room temperature with UV detection at 254 nm. The mobile phase was composed of methanol:water (65:35, v/v, 2% acetic acid) mixture, and flow rate was set to 1 mL/min. The method was validated according to the international guidelines with respect to linearity range, stability, limit of quantitation and detection, precision and accuracy. The method was linear within 5 – 100 μg/mL range with a correlation coefficient of 0.9995. The intra- and inter-assay precisions presented RSD values lower than 2%. The method reported is a fast and reliable HPLC method useful for QE determination in ME based gel formulations.