A certain proportion of docosahexaenoic acid tends to revert structural and dynamical effects of cholesterol on lipid membranes

Safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder: A systematic review and network meta-analysis

OBJECTIVE

To systematically evaluate the safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder (ADHD).

METHODS

Randomized controlled trials and prospective studies on antioxidant therapy in children and adolescents with ADHD were searched in PubMed, Embase, and Cochrane Library from the inception of databases to November 12, 2022. Two investigators independently screened the literature, extracted data, and evaluated the quality of the included studies. Network meta-analysis (PROSPERO registration number CRD 42023382824) was carried out by using R Studio 4.2.1.

RESULTS

48 studies involving 12 antioxidant drugs (resveratrol, pycnogenol, omega-3, omega-6, quercetin, phosphatidylserine, almond, vitamin D, zinc, folic acid, ginkgo biloba, Acetyl-L-carnitine) were finally included, with 3,650 patients. Network meta-analysis showed that omega-6 (0.18), vitamin D (0.19), and quercetin (0.24) were the top three safest drugs according to SUCRA. The omega-3 (SUCRA 0.35), pycnogenol (SUCRA 0.36), and vitamin D (SUCRA 0.27) were the most effective in improving attention, hyperactivity, and total score of Conners' parent rating scale (CPRS), respectively. In terms of improving attention, hyperactivity, and total score of Conners' teacher rating scale (CTRS), pycnogenol (SUCRA 0.32), phosphatidylserine+omega-3 (SUCRA 0.26), and zinc (SUCRA 0.34) were the most effective, respectively. In terms of improving attention, hyperactivity and total score of ADHD Rating Scale-Parent, the optimal agents were phosphatidylserine (SUCRA 0.39), resveratrol+MPH (SUCRA 0.24), and phosphatidylserine (SUCRA 0.34), respectively. In terms of improving attention, hyperactivity and total score of ADHD Rating Scale-Teacher, pycnogenol (SUCRA 0.32), vitamin D (SUCRA 0.31) and vitamin D (SUCRA 0.18) were the optimal agents, respectively. The response rate of omega-3+6 was the highest in CGI (SUCRA 0.95) and CPT (SUCRA 0.42).

CONCLUSION

The rankings of safety and efficacy of the 12 antioxidants vary. Due to the low methodological quality of the included studies, the probability ranking cannot fully explain the clinical efficacy, and the results need to be interpreted with caution. More high-quality studies are still needed to verify our findings.

Key structural factors and intermolecular interactions underlying the formation, functional properties and behaviour in the gastrointestinal tract in vitro of the liposomal form of nutraceuticals coated with whey proteins and chitosan

The aim of this study was to gain a better understanding of the key structural factors and intermolecular interactions underlying the formation, functionality, and in vitro gastrointestinal behaviour of the liposomal form of nutraceuticals coated with whey proteins (WPI) and chitosan (CHIT). Phosphatidylcholine (PC) liposomes were used to encapsulate a combination of hydrophobic and hydrophilic nutraceuticals. The hydrophobic constituents were long-chain (LC) n-3 PUFAs (DHA and EPA) from fish oil (FO), vitamin D3, and clove essential oil (CEO), while the hydrophilic component was γ-aminobutyric acid (GABA). A combination of physicochemical methods was used to achieve this goal, including electron paramagnetic resonance spectroscopy (EPRS), laser light scattering in dynamic, static, and electrophoretic modes, transmission electron microscopy, spectrophotometry and tensiometry. The efficiency of encapsulating the nutraceuticals in PC liposomes simultaneously was as follows: 100 ± 1% for both FO triglycerides and CEO, 82 ± 2% for vitamin D3, and 50 ± 1% for GABA. According to EPRS data, encapsulating LC PUFA reduced microviscosity at a depth of 20 Å in the PC bilayer. The co-encapsulation of other nutraceuticals in PC liposomes at selected concentrations did not alter this effect. The upper part (8 Å) of PC liposome bilayers showed an increase in rigidity parameter S, indicating the presence of D3, CEO, and partially GABA. The liposome layer-by-layer encapsulation efficiency (EE%) was achieved by using WPI to form the binary complex [WPI-(PC-FO-D3-GABA-CEO)] (EE = 50% at pH 7.0 and I = 0.001 M), followed by coating with chitosan to form the ternary complex [WPI-(PC-FO-D3-GABA-CEO)]-CHIT (EE = 80% at pH 5.1 and I = 0.001 M). The biopolymer-coated liposomes displayed high water solubility owing to their submicron sizes, thermodynamic affinity for the aqueous medium, and 20 mV ζ-potential values. The chitosan shell regulated the release of liposomes from the ternary complex during in vitro gastrointestinal digestion. In the stomach, the hydrolysis of chitosan by pepsin resulted in a 40% release of liposomes. In the small intestine, chitosan was separated from the WPI-liposome core, facilitatig its hydrolysis and resulting in a 60% release of liposomes. The bioavailability of nutraceuticals encapsulated in PC liposomes in the small intestine may be enhanced by the interactions of both non-hydrolysed and hydrolysed liposomes with bile salts and mucin.

Molecular View on the Impact of DHA Molecules on the Physical Properties of a Model Cell Membrane

Docosahexaenoic acid (DHA) is a ω-3 polyunsaturated fatty acid, which can be uptaken by cells and is essential for proper neuronal and retinal function. However, the detailed physical impact of DHA molecules on the plasma membrane is still unclear. Hence, in this work, we carried out μs-scale coarse-grained molecular dynamics (MD) simulations to reveal the interactions between DHA molecules and a model cell membrane. As is known, the cell membrane can segregate into liquid-ordered (L_o) and liquid-disordered (L_d) membrane domains due to the differential interactions between lipids and proteins. In order to capture this feature, we adopted the three-component phase-separated lipid membranes and considered both anionic and neutral DHA molecules in the current work. Our results showed that DHA molecules can spontaneously self-assemble into nanoclusters, fuse with lipid membranes, and localize preferably in L_d membrane domains. During the membrane fusion process, DHA molecules can change the intrinsic transmembrane potential of the lipid membrane, and the effects of anionic DHA molecules are much more significant. Besides, the presence of DHA molecules mainly in the L_d membrane domains could regulate the differences in the lipid chain order, membrane thickness, cholesterol preference, and cholesterol flip-flop basically in a concentration-dependent manner, which further promote the stability of the intraleaflet dynamics and inhibit the interleaflet dynamics (or promote membrane domain registration) of the membrane domains. In short, the impact of DHA molecules on the physical properties of a model cell membrane on the molecular level revealed in our work will provide useful insights for understanding the biological functions of DHA molecules.

The relationship between the structure and functionality of essential PUFA delivery systems based on sodium caseinate with phosphatidylcholine liposomes without and with a plant antioxidant: an in vitro and in vivo study

The aim of this work was to establish the main relationship between the structure and functionality of supramolecular complexes formed by sodium caseinate (SC) with phosphatidylcholine (PC) liposomes filled with fish oil (FO) to an equal mass ratio of n-3 to n-6 polyunsaturated fatty acids (PUFA) in the absence and presence of one of the most effective plant antioxidants, namely the essential oil of clove buds (EOC). The functionality of the supramolecular complexes (SC-PC-FO and SC-PC-FO-EOC) was considered from the point of view of the possibility of their use as effective delivery systems for long-chain n-3 PUFAs (eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids from FO). The laser light scattering method was used in the static, dynamic and electrophoretic modes to characterize the structure and thermodynamic parameters of the supramolecular complexes in an aqueous medium. It was found that the SC-PC-FO and SC-PC-FO-EOC complex particles had the following similar properties: nanosize; a spherical shape; 100% solubility in an aqueous medium (pH 7.0, ionic strength = 0.001 M); a high encapsulating ability of SC (up to 70%) in relation to the studied liposomes; and a high protective ability relative to lipid autooxidation (up to 96% on the 20th day of storage at room temperature in light). In addition, a sequential transformation of both the structural and thermodynamic parameters has been observed for the complex particles under in vitro simulated gastrointestinal (GI) conditions in accordance with the INFOGEST protocol. A greater release of the encapsulated lipids from the enzymatically hydrolyzed complex particles was observed at the small intestine stage compared to their release at the gastric stage. These data were in good agreement with those on the assessment of the bioavailability of the target PUFAs in in vivo experiments based on the chronic intake of aqueous solutions of the complexes (both SC-PC-FO and SC-PC-FO-EOC) by experimental mice for 92 days. Liver lipid profiles of the mice, obtained by gas-liquid chromatography, showed the following: (i) an almost twofold increase in the DHA content as compared with that of the control; (ii) an almost threefold decrease in the mass ratio of arachidonic acid (AA) (C20:4 n-6) to DHA (C22:6 n-3) compared to that of the control due to both a significant decrease in the AA content and a simultaneous pronounced increase in the DHA content; and (iii) an almost twofold decrease in the mass ratio of the total amounts of n-6 to n-3 PUFAs compared to that of the control.

On the Structure and Flip-flop of Free Docosahexaenoic Acid in a Model Human Brain Membrane

Among the omega-3 fatty acids, docosahexaenoic acid (DHA, sn22:6) is particularly vital in human brain cell membranes. There is considerable interest in DHA because low-level DHA has been associated with declined cognitive function and poor visual acuity. In this work, atomistic molecular dynamics simulations were used to investigate the effects of free protonated DHA (DHAP) in molar fractions of 0, 17, 30, and 38% in a realistic model of a healthy brain cell membrane comprising 26 lipid types. Numerous flip-flop events of DHAP were observed and categorized as successful or aborted. Novel use of the machine learning technique, density-based spatial clustering of applications with noise (DBSCAN), effectively identified flip-flop events by way of clustering. Our data show that increasing amounts of DHAP in the membrane disorder the bilayer packing, fluidize the membrane, and increase the rates of successful flip-flop from k = 0.2 μs^-1 (17% DHAP) to 0.8 μs^-1 (30% DHAP) and to 1.3 μs^-1 (38% DHAP). In addition, we also provided a detailed understanding of the flip-flop mechanism of DHAP across this complex membrane. Interestingly, we noted the role of hydrogen bonds in two distinct coordinated flip-flop phenomena between two DHAP molecules: double flip-flop and assisted flip-flop. Understanding the effects of various concentrations of DHAP on the dynamics within a lipid membrane and the resulting structural properties of the membrane are important when considering the use of DHAP as a dietary supplement or as a potential therapeutic.