Assaying the antioxidant and radical scavenging properties of aliphatic mono- and di-N-oxides in superoxide dismutase-deficient yeast and in a chemiluminescence test

Novel liposomal formulations for protection and delivery of levodopa: Structure-properties correlation

Liposomes are promising drug carriers for a wide range of central nervous system disorders, such as Parkinson's disease (PD), since they can protect active substances from degradation and could be administered intranasally, ensuring a direct access to the brain. Levodopa (LD), the drug commonly used to treat PD, spontaneously oxidizes in aqueous solutions and thus needs to be stabilized. Our investigation focuses on the preparation and the physico-chemical characterization of mixed liposomes to vehiculate LD and two natural substances (L-ascorbic acid and quercetin) that can prevent its oxidation and contribute to the treatment of Parkinson's disease. These co-loaded vesicles were prepared using a saturated phospholipid and structurally related cationic or analogue N-oxide surfactants and showed different properties, based on their composition. In particular, ex-vivo permeability tests using porcine nasal mucosa were performed, denoting that subtle variations of the lipids structure can significantly affect the delivery of LD to the target site.

Chemiluminescence Detection in the Study of Free-Radical Reactions. Part 1

The present review, consisting of two parts, considers the application of the chemiluminescence detection method in evaluating free radical reactions in biological model systems. The first part presents a classification of experimental biological model systems. Evidence favoring the use of chemiluminescence detection in the study of free radical reactions, along with similar methods of registering electromagnetic radiation as electron paramagnetic resonance, spectrophotometry, detection of infrared radiation (IR spectrometry), and chemical methods for assessing the end products of free radical reactions, is shown. Chemiluminescence accompanying free radical reactions involving lipids has been the extensively studied reaction. These reactions are one of the key causes of cell death by either apoptosis (activation of the cytochrome c complex with cardiolipin) or ferroptosis (induced by free ferrous ions). The concept of chemiluminescence quantum yield is also discussed in this article. The second part, which is to be published in the next issue, analyzes the application of chemiluminescence detection using luminescent additives that are called activators, a.k.a. chemiluminescence enhancers, and enhance the emission through the triplet-singlet transfer of electron excitation energy from radical reaction products, followed by light emission with a high quantum yield.

Access to New Cytotoxic Triterpene and Steroidal Acid-TEMPO Conjugates by Ugi Multicomponent-Reactions

Multicomponent reactions, especially the Ugi-four component reaction (U-4CR), provide powerful protocols to efficiently access compounds having potent biological and pharmacological effects. Thus, a diverse library of betulinic acid (BA), fusidic acid (FA), cholic acid (CA) conjugates with TEMPO (nitroxide) have been prepared using this approach, which also makes them applicable in electron paramagnetic resonance (EPR) spectroscopy. Moreover, convertible amide modified spin-labelled fusidic acid derivatives were selected for post-Ugi modification utilizing a wide range of reaction conditions which kept the paramagnetic center intact. The nitroxide labelled betulinic acid analogue 6 possesses cytotoxic effects towards two investigated cell lines: prostate cancer PC3 (IC₅₀ 7.4 ± 0.7 μM) and colon cancer HT29 (IC₅₀ 9.0 ± 0.4 μM). Notably, spin-labelled fusidic acid derivative 8 acts strongly against these two cancer cell lines (PC3: IC₅₀ 6.0 ± 1.1 μM; HT29: IC₅₀ 7.4 ± 0.6 μM). Additionally, another fusidic acid analogue 9 was also found to be active towards HT29 with IC₅₀ 7.0 ± 0.3 μM (CV). Studies on the mode of action revealed that compound 8 increased the level of caspase-3 significantly which clearly indicates induction of apoptosis by activation of the caspase pathway. Furthermore, the exclusive mitochondria targeting of compound 18 was successfully achieved, since mitochondria are the major source of ROS generation.

Synthesis and physicochemical characterization of new twin-tailed N-oxide based gemini surfactants

New gemini surfactants (GSs) constituted by two double alkyl chain (from 7 to 17 methylenic units) N-oxide monovalent surfactants joined by a PEG spacer of different length (from 3 to 21 ethylene glycol units), thus combining the properties of both N-oxide and GS surfactants, were synthetized and characterized. The different hydrophilic/hydrophobic balance of the molecular structure strongly influences the morphology and the electrical features of the aggregates. Despite the zwitterionic nature of the polar head groups, all the aggregates are characterized by positive potential thus suggesting protonation at the interface; however, the extent of protonation was shown to strongly depend on the length of the alkyl chain and of the spacer.