Synthesis, DNA/RNA-interaction and biological activity of benzo[k,l]xanthene lignans

Solid Lipid Nanoparticles Encapsulating a Benzoxanthene Derivative in a Model of the Human Blood-Brain Barrier: Modulation of Angiogenic Parameters and Inflammation in Vascular Endothelial Growth Factor-Stimulated Angiogenesis

Lignans, a class of secondary metabolites found in plants, along with their derivatives, exhibit diverse pharmacological activities, including antioxidant, antimicrobial, anti-inflammatory, and antiangiogenic ones. Angiogenesis, the formation of new blood vessels from pre-existing ones, is a crucial process for cancer growth and development. Several studies have elucidated the synergistic relationship between angiogenesis and inflammation in various inflammatory diseases, highlighting a correlation between inflammation and vascular endothelial growth factor (VEGF)-induced angiogenesis. Thus, the identification of novel molecules capable of modulating VEGF effects presents promising prospects for developing therapies aimed at stabilizing, reversing, or even arresting disease progression. Lignans often suffer from low aqueous solubility and, for their use, encapsulation in a delivery system is needed. In this research, a bioinspired benzoxantene has been encapsulated in solid lipid nanoparticles that have been characterized for their pharmacotechnical properties and their thermotropic behavior. The effects of these encapsulated nanoparticles on angiogenic parameters and inflammation in VEGF-induced angiogenesis were evaluated using human brain microvascular endothelial cells (HBMECs) as a human blood-brain barrier model.

Two novel synthetic xanthenodiones as antimicrobial, anti-adhesive and antibiofilm compounds against methicillin resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is widely recognized as a causative agent for various infections acquired in healthcare settings as well as in the community. Given the limited availability of effective antimicrobial agents to combat MRSA infections, there is an increasing need to explore alternative therapeutic strategies. This study aimed to assess the antimicrobial, anti-adhesive, anti-biofilm properties, and toxicity of 175 newly synthesized compounds, belonging to seven different classes, against MRSA. Initially, the compounds underwent screening for antimicrobial activity using the agar diffusion method. Subsequently, active compounds underwent further evaluation to determine their minimum inhibitory concentrations through microdilution. Anti-biofilm and anti-adhesive properties were assessed using the crystal violet method, while toxicity was tested using the alternative infection model Galleria mellonella. Among the tested compounds, two xanthenodiones exhibited the most promising activities, displaying bactericidal effects along with anti-adhesive and anti-biofilm properties. Moreover, the observed non-toxicity in G. mellonella larvae suggests that these compounds hold significant potential as alternative therapeutic options to address the escalating challenge of MRSA resistance in both hospital and community settings.

Selenium-Substituted Monomethine Cyanine Dyes as Selective G-Quadruplex Spectroscopic Probes with Theranostic Potential

The binding interactions of six ligands, neutral and monocationic asymmetric monomethine cyanine dyes comprising benzoselenazolyl moiety with duplex DNA and RNA and G-quadruplex structures were evaluated using fluorescence, UV/Vis (thermal melting) and circular dichroism (CD) spectroscopy. The main objective was to assess the impact of different substituents (methyl vs. sulfopropyl vs. thiopropyl/thioethyl) on the nitrogen atom of the benzothiazolyl chromophore on various nucleic acid structures. The monomethine cyanine dyes with methyl substituents showed a 100-fold selectivity for G-quadruplex versus duplex DNA. Study results indicate that cyanines bind with G-quadruplex via end π-π stacking interactions and possible additional interactions with nucleobases/phosphate backbone of grooves or loop bases. Cyanine with thioethyl substituent distinguishes duplex DNA and RNA and G-quadruplex structures by distinctly varying ICD signals. Furthermore, cell viability assay reveals the submicromolar activity of cyanines with methyl substituents against all tested human cancer cell lines. Confocal microscopy analysis shows preferential accumulation of cyanines with sulfopropyl and thioethyl substituents in mitochondria and indicates localization of cyanines with methyl in nucleus, particularly nucleolus. This confirms the potential of examined cyanines as theranostic agents, possessing both fluorescent properties and cell viability inhibitory effect.

Benzo[k,l]xanthene Lignan-Loaded Solid Lipid Nanoparticles for Topical Application: A Preliminary Study

Skin is the first human barrier that is daily exposed to a broad spectrum of physical and chemical agents, which can increase reactive oxygen species (ROS) and lead to the formation of topical disorders. Antioxidant molecules, such as benzo[k,l]xanthene lignans (BXL), are ideal candidates to eliminate or minimize the effects of ROS. Herein, we aimed to formulate BXL-loaded solid lipid nanoparticles (SLN-BXL) to improve the bioavailability and interaction with the skin, and also to investigate the protective impact against intracellular ROS generation in HFF-1 in comparison with the drug-free situation. SLN-BXL were formulated using the PIT/ultrasonication method, and then were subjected to physicochemical characterizations, i.e., average size, zeta potential (ZP), polydispersity index (PDI), encapsulation efficiency (%EE), thermotropic behavior, and interaction with a biomembrane model. The results show a mean size around 200 nm, PDI of 0.2, and zeta potential of about -28 mV, with values almost unchanged over a period of three months, while the EE% is ≈70%. Moreover, SLN-BXL are able to deeply interact with the biomembrane model, and to achieve a double-action release in mildly hydrophobic matrices; the results of the in vitro experiments confirm that SLN-BXL are cell-safe and capable of attenuating the IL-2-induced high ROS levels. In conclusion, based on our findings, the formulation can be proposed as a candidate for a preventive remedy against skin disorders induced by increased levels of ROS.

Characterization and Interaction with Biomembrane Model of Benzo[k,l]xanthene Lignan Loaded Solid Lipid Nanoparticles

Benzo[k,l]xanthene lignans are a group of rare natural products belonging to the class of polyphenols with promising biological activities and are studied as potential chemotherapeutic agents. The lipophilic character of a xanthene core makes these molecules difficult to be used in an aqueous medium, limiting their employment in studies for pharmaceutical applications. To overcome this problem, a drug-delivery system which is able to improve the stability and bioavailability of the compound can be used. In this study, a bioactive benzoxanthene lignan (BXL) has been included in SLN. Unloaded and BXL-loaded SLN have been prepared using the Phase Inversion Temperature method and characterized in terms of size, zeta potential, entrapment efficiency and stability. Differential scanning calorimetry was used to evaluate the thermotropic behavior and ability of SLN to act as carriers for BXL. A biomembrane model, represented by multilamellar vesicles, was used to simulate the interaction of the SLN with the cellular membrane. Unloaded and loaded SLN were incubated with the MLV, and their interactions were evaluated through variations in their calorimetric curves. The results obtained suggest that SLN could be used as a delivery system for BXL.