Absorption​ of free radicals in the body cannot be done by antioxidant compounds originating from the human body, so exogenous antioxidants are required to help in their natural antioxidant action. Oxidative stress can be caused by an imbalance of free radical inhibitors and the accumulation of free radicals that enter cellular structures. Synthetic antioxidants found in external antioxidants are not the primary choice because they are harmful and carcinogenic. Therefore, using natural ingredients provides a necessary alternative to constructing novel natural antioxidants. Recent studies have highlighted critical analysis and evaluation that flavonoids are a unique class of secondary metabolites found in plants and used in communities as traditional therapeutics with proven bioactivity. This could support new discoveries based on various herbal medicines and in addition, the functional effectiveness of flavonoids as antioxidants against free radicals. In this review, there are several strengths in the discussion. First, the study takes a comprehensive approach by covering various aspects, including the properties and sources of free radicals, oxidative stress in relation to different diseases, antioxidant defense mechanisms, and the specific antioxidant mechanisms of flavonoids. Second, the focus on natural antioxidants, especially flavonoids, and also discussion about clinical applications and human studies, limitations, global perspectives, and future research directions of flavonoids compounds become references in the selection of natural medicines. But, several constraints should be considered when interpreting the findings of this review. First, the discussion about the mechanism of antioxidant compounds is only discussed in general and only takes one example of a compound (flavonoid) that has the potential as an antioxidant. Second, the lack of findings regarding the relationship between several diseases discussed with free radicals. Third, a limited number of studies investigated regarding clinical applications and human studies of some of the diseases discussed.

Lipid nanoparticles (LNPs) have emerged as a promising delivery system, particularly for genetic therapies and vaccines. LNP formation requires a specific mixture of nucleic acid in a buffered solution and lipid components in ethanol. Ethanol acts as a lipid solvent, aiding the formation of the nanoparticle’s core, but its presence can also affect LNP stability. In this study, we used molecular dynamics (MD) simulations to investigate the physicochemical effect of ethanol on LNPs and gain a dynamic understanding of its impact on the overall structure and stability of LNPs. Our results demonstrate that ethanol destabilizes LNP structure over time, indicated by increased root mean square deviation (RMSD) values. Changes in the solvent-accessible surface area (SASA), electron density, and radial distribution function (RDF) also suggest that ethanol affects LNP stability. Furthermore, our H-bond profile analysis shows that ethanol penetrates the LNP earlier than water. These findings emphasize the importance of immediate ethanol removal in lipid-based systems during LNP production to ensure stability.

Epithelial sodium channel (ENaC) is a transmembrane protein that has an essential role in maintaining the levels of sodium in blood plasma. A person with a family history of hypertension has a high enough amount of ENaC protein in the kidneys or other organs, so that the ENaC protein acts as a marker that a person is susceptible to hypertension. An aptasensor involves aptamers, which are oligonucleotides that function similar to antibodies, as sensing elements. An electrochemical aptasensor for the detection of ENaC was developed using a screen-printed carbon electrode (SPCE) which was modified by electrodeposition of cerium oxide (CeO ₂ ). The aptamer immobilization was via the streptavidin–biotin system. The measurement of changes in current of the active redox [Fe(CN) ₆ ] ^3−/4− was carried out by differential pulse voltammetry. The surfaces of SPCE and SPCE/CeO ₂ were characterized using scanning electron microscopy, voltammetry and electrochemical impedance spectroscopy. The Box–Behnken experimental optimization design revealed the streptavidin incubation time, aptamer incubation time and streptavidin concentrations were 30 min, 30 min and 10.8 µg ml ⁻¹ , respectively. Various concentrations of ENaC were used to obtain the linearity range of 0.05–3.0 ng ml ⁻¹ , and the limits of detection and quantification were 0.012 ng ml ⁻¹ and 0.038 ng ml ⁻¹ , respectively. This aptasensor method has the potential to measure the ENaC protein levels in urine samples as well as to be a point-of-care device.

Flavonoids are a secondary metabolite group with various bioactivities, such as antioxidants. They are rich in the genus Erythrina, such as Erythrina crista-galli. This research aims to isolate and characterize flavonoids from the twigs of E. crista-galli and determine their antioxidant properties through in silico and in vitro assays. The ethyl acetate extract of E. crista-galli twigs were separated by column chromatography and characterized using spectroscopic methods. Density functional theory (DFT) calculations were performed on the isolated flavonoids and the reference compounds (ascorbic acid and quercetin) to obtain global descriptive parameters and a donor–acceptor map (DAM). We successfully isolated lupinifolin (1) and citflavanone (2) for the first time from E. crista-galli, along with lonchocarpol A (3), which has been discovered previously. The DAM suggests that these flavanones are good antiradicals with effective electron donors. However, they tend to be electron acceptors in methanol. The frontier molecular orbital analysis implies that lupinifolin (1) is a better antiradical than the other flavanones. The DPPH assays show that lupinifolin (1) has the highest antioxidant (antiradical) activity, with an IC₅₀ value of 128.64 ppm. The in silico studies showed similar trends to the in vitro assays using the DPPH method.

(-)-Balanol is an ATP mimic that inhibits protein kinase C (PKC) isozymes and cAMP-dependent protein kinase (PKA) with limited selectivity. While PKA is a tumour promoter, PKC isozymes act as tumour promoters or suppressors, depending on the cancer type. In particular, PKCε is frequently implicated in cancer promotion, making it a potential target for anticancer drugs. To improve isozyme selectivity of balanol, exhaustive structural and activity relationship (SAR) studies have been performed in the last two decades, but with limited success. More recently, fluorination on balanol has shown improved selectivity for PKCε, although the fluorine effect is not yet clearly understood. Understanding the origin to this fluorine-based selectivity will be valuable for designing better balanol-based ATP mimicking inhibitors. Computational approaches such as molecular dynamics (MD) simulations can decipher the fluorine effect, provided that correct charges have been assigned to a ligand. Balanol analogues have multiple ionisable functional groups and the effect of fluorine substitutions on the exact charge state of each analogue bound to PKA and to PKCε needs to be thoroughly investigated in order to design highly selective inhibitors for therapeutic applications. We explored the charge states of novel fluorinated balanol analogues using MD simulations. For different potential charge states of these analogues, Molecular Mechanics Generalized Born Surface Area (MMGBSA) binding energy values were computed. This study suggests that balanol and the most potent fluorinated analogue (5S fluorine substitution on the azepane ring), have charges on the azepane ring (N1), and the phenolic (C6′′OH) and the carboxylate (C15′′O₂H) groups on the benzophenone moiety, when bound to PKCε as well as PKA. To the best our knowledge, this is the first study showing that the phenolate group is charged in balanol and its analogues binding to the ATP site of PKCε. Correct charge assignments of ligands are important to obtain predicted binding energy values from MD simulations that reflect experimental values. Both fluorination and the local enzymatic environment of the ATP site can influence the exact charge states of balanol analogues. Overall, this study is highly valuable for further rational design of potent balanol analogues selective to PKCε.

Enhanced selectivity for homologous ATP sites by composite chemical and conformational perturbation by stereospecific fluorination.