Effects of Four Different Dietary Fibre Supplements on Weight Loss and Lipid and Glucose Serum Profiles during Energy Restriction in Patients with Traits of Metabolic Syndrome: A Comparative, Randomized, Placebo-Controlled Study.

Obesity and its associated complications require various lifestyle changes and treatment options. Dietary supplements are considered an attractive alternative to traditional therapy, mainly because they are accessible to the general population. The aim of this study was to investigate the additive effects of a combination of energy restriction (ER) and four dietary supplements on changes in the anthropometric and biochemical parameters in 100 overweight or obese participants who were randomly assigned one of the dietary fibre supplements containing different dietary fibres or a placebo for 8 weeks. The results confirmed that fibre supplements plus ER significantly (p < 0.01) reduced the body weight, body mass index (BMI), fat mass, and visceral fat and ameliorated the lipid profile and inflammation at 4 and 8 weeks after the start of the study, while in the placebo group, significant differences in some parameters were observed only after 8 weeks of ER. A fibre supplement containing glucomannan, inulin, psyllium, and apple fibre was the most effective at reducing the BMI, body weight, and CRP (p = 0.018 for BMI and body weight and p = 0.034 for CRP compared to placebo at the end of the intervention). Overall, the results suggest that dietary fibre supplements in combination with ER may have additional effects on weight loss and the metabolic profile. Therefore, taking dietary fibre supplements may be a feasible approach to improve weight and metabolic health in obese and overweight individuals.

Effect of growth medium pH of Aeropyrum pernix on structural properties and fluidity of archaeosomes.

The influence of pH (6.0; 7.0; 8.0) of the growth medium of Aeropyrum pernix K1 on the structural organization and fluidity of archaeosomes prepared from a polar-lipid methanol fraction (PLMF) was investigated using fluorescence anisotropy and electron paramagnetic resonance (EPR) spectroscopy. Fluorescence anisotropy of the lipophilic fluorofore 1,6-diphenyl-1,3,5-hexatriene and empirical correlation time of the spin probe methylester of 5-doxylpalmitate revealed gradual changes with increasing temperature for the pH. A similar effect has been observed by using the trimethylammonium-6-diphenyl-1,3,5-hexatriene, although the temperature changes were much smaller. As the fluorescence steady-state anisotropy and the empirical correlation time obtained directly from the EPR spectra alone did not provide detailed structural information, the EPR spectra were analysed by computer simulation. This analysis showed that the archaeosome membranes are heterogeneous and composed of several regions with different modes of spin-probe motion at temperatures below 70°C. At higher temperatures, these membranes become more homogeneous and can be described by only one spectral component. Both methods indicate that the pH of the growth medium of A. pernix does not significantly influence its average membrane fluidity. These results are in accordance with TLC analysis of isolated lipids, which show no significant differences between PLMF isolated from A. pernix grown in medium with different pH.

Structural characterization of liposomes made of diether archaeal lipids and dipalmitoyl-L-α-phosphatidylcholine.

The physicochemical properties of binary lipid mixtures of diether C(25,25) lipids and dipalmitoyl-L-α-phosphatidylcholine (DPPC) were studied using photon correlation, fluorescence and electron paramagnetic resonance spectroscopy, and transmission electron microscopy. These two types of lipids can be mixed at all molar ratios to form unilamellar and multilamellar liposomes. Fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatrien in mixed liposomes indicates that the abrupt changes in order parameter in the hydrophobic part of bilayer membranes made of DPPC lipids disappears with increasing mol%C(25,25) lipids. Electron paramagnetic resonance spectroscopy shows that at temperatures below 50 °C, the interfacial regions of membrane bilayer of mixed liposomes is more fluid than for pure DPPC liposomes, while at higher temperatures, the impact of the long isoprenoid chains on the membrane stability becomes more pronounced. Photon correlation spectroscopy and transmission electron microscopy show that mixed liposomes do not fuse or aggregate, even after 41 days at 4 °C.

Stability of diether C(25,25) liposomes from the hyperthermophilic archaeon Aeropyrum pernix K1.

Temperature and pH effects were studied for stability, structural organization, fluidity and permeability of vesicles from a polar lipid methanol fraction isolated from the Aeropyrum pernix. We determined the permeability of C(25,25) liposomes using fluorescence intensity of released calcein. At pH 7.0 and 9.0, and from 85°C to 98°C, only 10% of entrapped calcein was released. After 10 h at 90°C, calcein release reached 27%, independent of pH. Fluorescence anisotropy measurements of hydrophobic probe 1,6-diphenyl-1,3,5-hexatriene revealed gradual changes up to 60°C. At higher temperatures, the anisotropy did not change significantly. Fluorescence alone did not provide detailed and direct structural information about these C(25,25) liposomes, so we used electron paramagnetic resonance spectroscopy (EPR) and differential scanning calorimetry (DSC). From EPR spectra, mean membrane fluidity determined according to maximal hyperfine splitting and empirical correlation times showed continuous increases with temperature. Computer simulation of EPR spectra showed heterogeneous membranes of these C(25,25) liposomes: at low temperatures, they showed three types of membrane regions characterized by different motional modes. Above 65°C, the membrane becomes homogeneous with only one fluid-like region. DSC thermograms of C(25,25) liposomes reveal a very broad and endothermic transition in the temperature range from 0°C to 40°C.

Structural and physicochemical properties of polar lipids from thermophilic archaea.

The essential general features required for lipid membranes of extremophilic archaea to fulfill biological functions are that they are in the liquid crystalline phase and have extremely low permeability of solutes that is much less temperature sensitive due to a lack of lipid-phase transition and highly branched isoprenoid chains. Many accumulated data indicate that the organism's response to extremely low pH is the opposite of that to high temperature. The high temperature adaptation does not require the tetraether lipids, while the adaptation of thermophiles to acidic environment requires the tetraether polar lipids. The presence of cyclopentane rings and the role of polar heads are not so straightforward regarding the correlations between fluidity and permeability of the lipid membrane. Due to the unique lipid structures and properties of archaeal lipids, they are a valuable resource in the development of novel biotechnological processes. This microreview focuses primarily on structural and physicochemical properties of polar lipids of (hyper)thermophilic archaea.