Low-Molecular-Weight Synthetic Antioxidants: Classification, Pharmacological Profile, Effectiveness and Trends

Dendrobium officinale flos water extract ameliorates ethanol-induced acute gastric mucosal injury via inhibiting oxidative stress and inflammation

BACKGROUND

Dendrobium officinale flos (DOF), a novel food raw material, is used in Chinese folk medicine to nourish the stomach. However, there is still no available study to evaluate the effects of DOF on animal models of acute gastric injury and its mechanism by modern pharmacological research.

RESULTS

Herein, we characterized the major components of an aqueous extract of DOF and assessed its potential ameliorative effects in a rat model of acute gastric mucosal injury. The DOF water extract showed significant protective effects on the gastric mucosa and exhibited excellent antioxidant and anti-inflammatory activities. Acute gastric injury rat models induced by ethanol (6 mL kg-1) were pretreated with different doses of DOF water extract (50-100 mg kg-1 day-1), and the biological effects of DOF extract in gastric tissues were evaluated. DOF extract alleviated the symptoms of ethanol-stimulated acute gastric mucosal injury, as evidenced by a significant reduction in gastric injury index and the degree of gastric pathological changes. Additionally, treatment with DOF extract upregulated mucin expression in the gastric mucosa, attenuated oxidative stress, decreased the release of inflammatory mediators (TNF-α, IL-6), suppressed the expression of key proinflammatory enzymes (COX-2 and iNOS), reduced the phosphorylation of p38 MAPK and p65 NF-κB and increased the level of PGE2 in gastric tissues.

CONCLUSION

DOF exerts protective effects against ethanol-induced acute gastric mucosal injury, mainly by inhibiting inflammation and oxidative stress. © 2024 Society of Chemical Industry.

Novel acrylonitrile derived imidazo[4,5-b]pyridines as antioxidants and potent antiproliferative agents for pancreatic adenocarcinoma

We present the design, synthesis, computational analysis, and biological assessment of several acrylonitrile derived imidazo[4,5-b]pyridines, which were evaluated for their anticancer and antioxidant properties. Our aim was to explore how the number of hydroxy groups and the nature of nitrogen substituents influence their biological activity. The prepared derivatives exhibited robust and selective antiproliferative effects against several pancreatic adenocarcinoma cells, most markedly targeting Capan-1 cells (IC50 1.2-5.3 μM), while their selectivity was probed relative to normal PBMC cells. Notably, compound 55, featuring dihydroxy and bromo substituents, emerged as a promising lead molecule. It displayed the most prominent antiproliferative activity without any adverse impact on the viability of normal cells. Furthermore, the majority of studied derivatives also exhibited significant antioxidative activity within the FRAP assay, even surpassing the reference molecule BHT. Computational analysis rationalized the results by highlighting the dominance of the electron ionization for the antioxidant features with the trend in the computed ionization energies well matching the observed activities. Still, in trihydroxy derivatives, their ability to release hydrogen atoms and form a stable O-H⋯O•⋯H-O fragment upon the H• abstraction prevails, promoting them as excellent antioxidants in DPPH• assays as well.

Development of Nanostructured Lipid Carrier-Loaded Flavonoid-Enriched Zingiber officinale

Flavonoids, which are bioactive molecules found in Zingiber officinale, have been widely used as antioxidant and anti-inflammatory drugs. The presence of nanostructured lipid carriers (NLCs) as sophisticated delivery systems for bioactive compounds, such as flavonoids, can increase their bioavailability and stability, thus potentially producing better therapeutic effects. This study aimed to develop an anti-inflammatory topical gel using NLC-containing flavonoids derived from Zingiber officinale. The NLC formulation was prepared using stearic acid, a mixture of medium-chain triglycerides and isopropyl myristate, Tween 20, and Span 20 by using a hot homogenization method. The total flavonoid content obtained through sequential maceration stages was 4.04 mg of QUE/g of dry extract. The highest encapsulation efficiency of flavonoid-loaded NLC was observed at a flavonoid, Zingiber officinale extract (ZOE) concentration of 2%. It was found that a ZOE concentration of 0.4% provided excellent stability with a particle size of 302-344 nm and a polydispersity index of 0.14-0.23 after 28 days of observation. Morphological analysis of the ZOE-loaded NLC revealed a stable and well-developed formulation with a fairly uniform distribution. The presence of distinctive and uniformly distributed single particles suggests a promising alternative drug delivery system for conventional topical preparations. ZOE-loaded NLC gel showed solid-like properties and higher quality stability than the gel.

Evaluating the Incorporation of Myrtus communis L. Leaves Infusion in Alginate-Based Films and Spheres to Enhance the Oxidative Stability of Oil-in-Water Emulsions

Myrtus communis L. is a species of the Myrtaceae family that is found in the Mediterranean region, and it is traditionally recognized for its importance and different uses. The objective of this study was to determine the effect of M. communis L. leaf extract (MCLE), which was incorporated directly into alginate spheres and films, on preserving oil-in-water emulsions from oxidation. For this purpose, the solvent extraction (with ethanol at 40, 60, and 80%) of the antioxidant compounds was optimized (total phenolic compounds (TPCs) and total flavonoid content (TFC)) along with the scavenging activity. The best condition for the extraction corresponded with 60% ethanol (MCLE60), with a TPC of ~66.06 g GAE/L and a TFC of ~18.91 g QE/L, which was selected for use in the following assays. MCLE60 showed a considerable radical scavenging activity (24.85 mmol TE/L in FRAP, 28.75 mmol TE/L in DPPH, 30.61 mmol TE/L in ABTS, and 14.94 mmol TE/L in ORAC), which was probably due to its content in the phenolic compounds arbutin (122.08 mg/L), epicatechin (73.89 mg/L), sinapic acid (51.85 mg/L), and gallic acid (36.72 mg/L). The oil-in-water emulsions with the MCLE60 spheres showed the best oxidative stability (TBARS ~2.64 mg MDA/kg of emulsion, PV ~35.7 meq hydroperoxides/kg of emulsion) in comparison to the control. The film was also able to protect the emulsion from oxidation for more than a week at 30 °C (TBARS ~1.9 mg MDA/kg of emulsion). The alginate films with MCLE60 presented an important release of phenolic compounds in water and acetic food simulants, while in both ethanol simulants, the release of TPC remained more stable over time. Thus, this study highlights the potential uses of MCLE as a natural ingredient for emulsion oxidative preservation and the production of alginate delivery systems (spheres and films).

Synthesis and glutathione peroxidase (GPx)-like activity of selenocystine (SeC) bioconjugates of biotin and lipoic acid

The conjugation of active biomolecules provides insight into their bioreactivity, leading to many applications in biotechnology and materials science. Herein, we report L-selenocystine (SeC) bioconjugates of lipoic acid (universal antioxidant) and biotin (Vitamin-H). The SeC-bioconjugates, SeC-Biotin (1) and SeC-Lipoic acid (2) were synthesized using solid phase peptide synthesis (SPPS) method and were characterized by multinuclear 1D (1H, 13C, 77Se) and 2D (1H-1H COSY and 1H-13C TOCSY) NMR spectroscopy, ESI-MS spectrometry, and RP-HPLC. The GPx-like enzyme mimicking activity of the SeC-bioconjugates 1 and 2 has been investigated through the coupled reductase assay method for the catalytic reductions of hydrogen peroxide into water. A significant enhancement in GPx-like enzymatic activity was observed for both novel bioconjugates SeC-Biotin (1) and SeC-Lipoic acid (2) as compared to diphenyl diselenide (Ph2Se2), L-selenocystine (SeC), biotin, lipoic acid, and ebselen.

Synthesis, Evaluation of Enzyme Inhibition and Redox Properties of Potential Dual COX-2 and 5-LOX Inhibitors

Various dual inhibitors of COX-2 and 5-LOX enzymes have been developed so far in order to obtain more effective and safer anti-inflammatory drugs. The aim of this study was to design and synthesize new dual COX-2 and 5-LOX inhibitors, and to evaluate their enzyme inhibition potential and redox properties. Thirteen compounds (1-13) were designed taking into account structural requirements for dual COX-2 and 5-LOX inhibition and antioxidant activity, synthesized, and structurally characterized. These compounds can be classified as N-hydroxyurea derivatives (1, 2 and 3), 3,5-di-tert-butylphenol derivatives (4, 5, 6, 7 and 13), urea derivatives (8, 9 and 10) and "type B hydroxamic acids" (11 and 12). COX-1, COX-2 and 5-LOX inhibitory activities were evaluated using fluorometric inhibitor screening kits. The evaluation of the redox activity of newly synthesized compounds was performed in vitro in the human serum pool using redox status tests. The prooxidative score, the antioxidative score and the oxy-score were calculated. Seven out of thirteen synthesized compounds (1, 2, 3, 5, 6, 11 and 12) proved to be dual COX-2 and 5-LOX inhibitors. These compounds expressed good COX-2/COX-1 selectivity. Moreover, dual inhibitors 1, 3, 5, 11 and 12 showed good antioxidant properties.

Synergistic or antagonistic antioxidant combinations - a case study exploring flavonoid-nitroxide hybrids

Neurodegenerative diseases impose a considerable medical and public health burden on populations throughout the world. Oxidative stress, an imbalance in pro-oxidant/antioxidant homeostasis that leads to the generation of reactive oxygen species (ROS), has been implicated in the progression of a number of neurodegenerative diseases. The manipulation of ROS levels may represent a promising treatment option to slow down neurodegeneration, although adequate potency of treatments has not yet been achieved. Using a hybrid pharmacology approach, free radical nitroxide antioxidants were hybridised with a class of natural antioxidants, flavonoids, to form a potential multitargeted antioxidant. Modification of the Baker-Venkataraman reaction achieved the flavonoid-nitroxide hybrids (6-9) in modest yields. Antioxidant evaluation of the hybrids by cyclic voltammetry showed both redox functionalities were still active, with little influence on oxidation potential. Assessment of the peroxyl radical scavenging ability through an ORAC assay showed reduced antioxidant activity of the hybrids compared to their individual components. It was hypothesized that the presence of the phenol in the hybrids creates a more acidic medium which does not favour regeneration of the nitroxide from the corresponding oxammonium cation, disturbing the typical catalytic cycle of peroxyl radical scavenging by nitroxides. This work highlights the potential intricacies involved with drug hybridization as a strategy for new therapeutic development.