Synthesis and interaction of sterol-uridine conjugate with DMPC liposomes studied by differential scanning calorimetry

Naringenin Release to Biomembrane Models by Incorporation into Nanoparticles. Experimental Evidence Using Differential Scanning Calorimetry

Naringenin (4′,5,7-trihydroxyflavanone-7-rhamnoglucosideor naringenin-7-rhamnoglucoside), a flavonoid present in large quantities in citrus, has different beneficial effects on human health as an antioxidant, free radical scavenger, anti-inflammatory, carbohydrate metabolism promoter, and immune system modulator. Different studies have shown that this substance also has a hypoglycemic and antihypertensive effect, reduces cholesterol and triglycerides, and plays an important protective role in the heart tissue; moreover, it provides neuroprotection against various neurological disorders such as Parkinson’s disease and unpredictable chronic stress-induced depression. Despite these advantages, Naringenin is poorly absorbed, and the small percentage absorbed is rapidly degraded by the liver, as a result losing its activity. Several approaches have been attempted to overcome these obstacles, among them, nanotechnology, with the use of Drug Delivery Systems (DDS) as Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC). DDS can, in fact, improve the drug bioavailability. The aim of this study was to develop and characterize SLN and NLC containing Naringenin and to evaluate the ability of these nanoparticles to release Naringenin at the cell level using biomembrane models represented by Multilamellar Vesicles (MLV). These studies were performed using Differential Scanning Calorimetry, a powerful technique to detect the interaction of drugs and delivery systems with MLV. It was shown that Naringenin could be better incorporated into NLC with respect to SLN and that Naringenin could be released by NLC into the biomembrane model. Therefore, suggesting the administration of Naringenin loaded into nanoparticles could help avoid the disadvantages associated with the use of the free molecule.

Ammonium glycyrrhizate skin delivery from ultradeformable liposomes: A novel use as an anti-inflammatory agent in topical drug delivery

Glycyrrhiza glabra L. is a native plant of Central and South-Western Asia that is also diffused in the Mediterranean area and contains several bioactive compounds such as: flavonoids, sterols, triterpene and saponins. Glycyrrhizin, containing glycyrrhizic and glycyrrhizinic acids has anti-inflammatory and antiallergic effects that are similar to corticosteroids. Ammonium glycyrrhizinate is a derivative salt of glycyrrhizic acid with similar anti-inflammatory activity that cannot pass through the skin due to its physicochemical properties and molecular weight. Although several nanoformulations, such as ethosomes, are designed to provide a systemic effect through a topical application, there are different limitations to the distribution inside the blood stream. For this reason, ultradeformable liposomes, or transfersomes, are selected to improve the topical delivery of drugs and allow the distribution of payloads in the blood stream because they pass intact through the stratum corneum epidermis barrier, due to the presence of sodium cholate, aqueous cutaneous gradient, and the rapid penetration of transfersomes by cutaneous tight junctions, thus allowing the systemic delivery of different therapeutic cargo in non-occlusive conditions. The aim of this work was the synthesis and physicochemical characterization of the ammonium glycyrrhizinate-loaded ultradeformable liposomes, the evaluation of drug release and permeation through stratum corneum and epidermis barrier. The in vivo anti-inflammatory effect of ammonium glycyrrhizinate-loaded ultradeformable liposomes was tested on human healthy volunteers. The results demonstrated that the ammonium glycyrrhizinate-loaded ultradeformable liposomes decreased the skin inflammation on the human volunteers and the resulting nanoformulations can be used as a potential topical drug delivery system for anti-inflammatory therapy. ^☆Parts of these results were presented as a poster communication at the Recent Developments in Pharmaceutical Analysis 2019 (RDPA 2019), Chieti, Italy.

Molecular Information on the Potential of Europium Complexes for Local Recognition of a Nucleoside-Based Drug by Using Nanostructured Interfaces Assembled as Langmuir-Blodgett Films

The production of nanostructured materials for biological and medical applications may be applied toward the conjugation of adequate substances to boost the stimulus response of sensors and diagnostic probes. In this sense, Langmuir-Blodgett films constituted of bioinspired and biomimetic materials have attracted attention because of the ease of manipulation of the molecular architecture. In this paper, we employed a nucleoside-based drug, which was linked with a sterol hydrophobic moiety (3',4'-acetonide-uridine-succinate-cholesterol conjugate) to provide it an amphiphilic character. The drug was spread on the air-water interface, alone or mixed with stearic acid, forming Langmuir monolayers, and the complex Eu(tta)₃(H₂O)₂ was incorporated in the drug-containing monolayer. Interactions at the air-water interface between stearic acid, the drug, and the europium complex were then investigated with tensiometry, surface potential, infrared spectroscopy, and Brewster angle microscopy. The Langmuir films were transferred to solid supports as Langmuir-Blodgett films, which presented luminescent properties that could be tuned according to the molecular architecture. We believe that these results can serve as a novel approach to characterize and assemble materials organized in the molecular scale for medical applications.

Phospholipid prodrug conjugates of insoluble chemotherapeutic agents for ultrasound targeted drug delivery

The hydrophobicity and high potency of many therapeutic agents makes them difficult to use effectively in clinical practice. This work focuses on conjugating phospholipid tails (2T) onto podophyllotoxin (P) and its analogue (N) using a linker and characterizing the effects of their incorporation into lipid-based drug delivery vehicles for triggered ultrasound delivery. Differential Scanning Calorimetry results show that successfully synthesized lipophilic prodrugs, 2T-P (~28 % yield) and 2T-N(~26 % yield), incorporate within the lipid membranes of liposomes. As a result of this, increased stability and incorporation are observed in 2T-P and 2T-N in comparison to the parent compounds P and N. Molecular dynamic simulation results support that prodrugs remain within the lipid membrane over a relevant range of concentrations. 2T-N's (IC₅₀: 20 nM) biological activity was retained in HeLa cells (cervical cancer), whereas 2T-P's (IC₅₀: ~4 µM) suffered, presumably due to steric hindrance. Proof-of-concept studies using ultrasound in vitro microbubble and nanodroplet delivery vehicles establish that these prodrugs are capable of localized drug delivery. This study provides useful information about the synthesis of double tail analogues of insoluble chemotherapeutic agents to facilitate incorporation into drug delivery vehicles. The phospholipid attachment strategy presented here could be applied to other well suited drugs such as gemcitabine, commonly known for its treatment of pancreatic cancer.

Cholesterol-induced physicochemical changes in dodecylamine-based metallosomes: drug entrapping ability and interactions with biological molecules

Multivesicular metallosomes have been synthesized from metal functionalized amphiphiles. They have been thoroughly characterized and explored for their entrapment efficiency towards drug and other biomolecules.