In modern societies, conscious consumers demand healthy, fresh and natural foods devoid of added chemical preservatives and stabilizers. The use of lactic acid bacteria (LAB) to preserve food is one ...of the oldest and best characterized approach. Production of organic acids is the main feature LAB use to outcompete spoilage organisms, but several other mechanisms have been demonstrated. In this review, a critical overview of the mechanisms used by LAB to inhibit spoilage organisms will be presented. Discrepancies between the concentrations of compounds resulting from LAB activity and their inhibitory amounts are discussed. Technical limitations hindering discoveries in this field as well as future trends in the application of LAB solutions to food bioprotection will be covered, including antifungal peptides and competitive exclusion.
The present study takes advantage of the beneficial effects of resveratrol as a neuroprotective compound. Resveratrol-loaded solid lipid nanoparticles were functionalized with apolipoprotein E which ...can be recognized by the LDL receptors overexpressed on the blood-brain barrier.
Transmission electron microscopy images revealed spherical nanoparticles, dynamic light scattering gave a Z-average lower than 200 nm, and a zeta potential of around -13 mV and very high resveratrol entrapment efficiency (ca. 90 %). In vitro cytotoxic effects were assessed by MTT and LDH assays in hCMEC/D3 cell line and revealed no toxicity up to 50 μM over 4 h of incubation. The permeability through hCMEC/D3 monolayers showed a significant increase (1.8-fold higher) for resveratrol-loaded solid lipid nanoparticles functionalized with apolipoprotein E when compared to non-functionalized ones.
In conclusion, these nanosystems might be a promising strategy for resveratrol delivery into the brain, while protecting it from degradation in the blood stream. Graphical abstract .
The blood-brain barrier (BBB) is a barrier that separates the blood from the brain tissue and possesses unique characteristics that make the delivery of drugs to the brain a great challenge. To ...achieve this purpose, it is necessary to design strategies to allow BBB passage, in order to reach the brain and target the desired anatomic region. The use of nanomedicine has great potential to overcome this problem, since one can modify nanoparticles with strategic molecules that can interact with the BBB and induce uptake through the brain endothelial cells and consequently reach the brain tissue. This review addresses the potential of nanomedicines to treat neurological diseases by using nanoparticles specially developed to cross the BBB.
The aggregation of amyloid-β peptide (Aβ) has been linked to the formation of neuritic plaques, which are pathological hallmarks of Alzheimer's disease (AD). Various natural compounds have been ...suggested as therapeutics for AD. Among these compounds, resveratrol has aroused great interest due to its neuroprotective characteristics. Here, we provide evidence that grape skin and grape seed extracts increase the inhibition effect on Aβ aggregation. However, after intravenous injection, resveratrol is rapidly metabolized into both glucuronic acid and sulfate conjugations of the phenolic groups in the liver and intestinal epithelial cells (within less than 2 h), which are then eliminated. In the present study, we show that solid lipid nanoparticles (SLNs) functionalized with an antibody, the anti-transferrin receptor monoclonal antibody (OX26 mAb), can work as a possible carrier to transport the extract to target the brain. Experiments on human brain-like endothelial cells show that the cellular uptake of the OX26 SLNs is substantially more efficient than that of normal SLNs and SLNs functionalized with an unspecific antibody. As a consequence, the transcytosis ability of these different SLNs is higher when functionalized with OX-26.
Abstract
The ability to produce polysaccharides with diverse biological functions is widespread in bacteria. In lactic acid bacteria (LAB), production of polysaccharides has long been associated with ...the technological, functional and health-promoting benefits of these microorganisms. In particular, the capsular polysaccharides and exopolysaccharides have been implicated in modulation of the rheological properties of fermented products. For this reason, screening and selection of exocellular polysaccharide-producing LAB has been extensively carried out by academia and industry. To further exploit the ability of LAB to produce polysaccharides, an in-depth understanding of their biochemistry, genetics, biosynthetic pathways, regulation and structure–function relationships is mandatory. Here, we provide a critical overview of the latest advances in the field of glycosciences in LAB. Surprisingly, the understanding of the molecular processes involved in polysaccharide synthesis is lagging behind, and has not accompanied the increasing commercial value and application potential of these polymers. Seizing the natural diversity of polysaccharides for exciting new applications will require a concerted effort encompassing in-depth physiological characterization of LAB at the systems level. Combining high-throughput experimentation with computational approaches, biochemical and structural characterization of the polysaccharides and understanding of the structure–function–application relationships is essential to achieve this ambitious goal.
This review describes the recent findings regarding exocellular polysaccharide production in lactic acid bacteria, and provides an overview of their applications in food and future trends in polysaccharide research.
Resveratrol is a polyphenol found in grapes and red wines. Interest in this polyphenol has increased due to its pharmacological cardio- and neuroprotective, chemopreventive, and antiaging effects, ...among others. Nevertheless, its pharmacokinetic properties are less favorable, since the compound has poor bioavailability, low water solubility, and is chemically unstable. To overcome these problems, we developed two novel resveratrol nanodelivery systems based on lipid nanoparticles to enhance resveratrol's oral bioavailability for further use in medicines, supplements, and nutraceuticals.
Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) loaded with resveratrol were successfully produced by a modified hot homogenization technique. These were completely characterized to evaluate the quality of the developed resveratrol-loaded nanoparticles.
Cryo-scanning electron microscopy morphology studies showed spherical and uniform nanoparticles with a smooth surface. An average resveratrol entrapment efficiency of ~70% was obtained for both SLNs and NLCs. Dynamic light scattering measurements gave a Z-average of 150-250 nm, polydispersity index of ~0.2, and a highly negative zeta potential of around -30 mV with no statistically significant differences in the presence of resveratrol. These characteristics remained unchanged for at least 2 months, suggesting good stability. Differential scanning calorimetry studies confirmed the solid state of the SLNs and NLCs at both room and body temperatures. The NLCs had a less ordered crystalline structure conferred by the inclusion of the liquid lipid, since they had lower values for phase transition temperature, melting enthalpy, and the recrystallization index. The presence of resveratrol induced a disorder in the crystal structure of the nanoparticles, suggesting a favoring of its entrapment. The in vitro release studies on conditions of storage showed a negligible resveratrol release over several hours for both nanosystems and the in vitro simulation of gastrointestinal transit showed that the resveratrol remained mostly associated with the lipid nanoparticles after their incubation in digestive fluids.
Both nanodelivery systems can be considered suitable carriers for oral administration, conferring protection to the incorporated resveratrol and allowing a controlled release after uptake.
Developing new easy‐to‐prepare functional drug delivery nanosystems with good storage stability, low hemotoxicity, as well as controllable drug delivery property, has attracted great attention in ...recent years. In this work, a cholesterol‐based prodrug nanodelivery system is prepared by self‐assembly of cholesterol‐doxorubicin prodrug conjugates (Chol‐Dox) and tocopherol polyethylene glycol succinate (TPGS) using thin‐film hydration method. The Chol‐Dox/TPGS assemblies (molar ratio 2:1, 1:1, and 1:2) are able to form nanoparticles with average hydrodynamic diameter of ≈140–214 nm, surface zeta potentials of ≈−24.2–−0.3 mV, and remarkable solution stability in 0.1 m PBS, 16 days). The Chol‐Dox/TPGS assemblies show low hemotoxicity and different cytotoxicity profiles in breast cancer cells (MCF‐7 and MDA‐MB‐231), which are largely dependent on the molar ratio of Chol‐Dox and TPGS. The Chol‐Dox/TPGS assemblies tend to enter into MCF‐7 and MDA‐MB‐231 cells through non‐Clathrin‐mediated multiple endocytosis and lysosome‐dependent uptake pathways, moreover, these nanoassemblies demonstrate lysosome‐dependent intracellular localization, which is different from that of free DOX (nuclear localization). The results demonstrate that the Chol‐Dox/TPGS assemblies are promising cholesterol‐based prodrug nanomaterials for breast cancer chemotherapy.
Practical Applications: This work demonstrates a lipid prodrug‐based nanotherapeutic system. Herein the Chol‐Dox/TPGS nanoassemblies could serve as promising and controllable cholesterol‐based prodrug nanomaterials/nano‐formulations for potential breast cancer chemotherapy.
In this work, prodrug‐based nanoassemblies (Chol‐Dox/TPGS) are prepared, which exhibit remarkable solution stability, low hemotoxicity, high cellular uptake and Chol‐Dox/TPGS ratio‐dependent cytotoxicity in breast cancer cells (MCF‐7 and MDA‐MB‐231). Moreover, the nanoassemblies enter into cells through non‐Clathrin‐mediated multiple endocytosis, lysosome‐dependent uptake pathways, and demonstrate lysosome‐localization, which is different from that of free DOX (nuclear localization).
Resveratrol was investigated in terms of its stability, biocompatibility and intestinal permeability across Caco-2 cell monolayers in its free form or encapsulated in solid lipid nanoparticles (SLNs) ...and nanostructured lipid carriers (NLCs). SLNs and NLCs presented a mean diameter between 160 and 190 nm, high negative zeta potential of -30 mV and resveratrol entrapment efficiency of 80%, suggesting they are suitable for resveratrol oral delivery. Nanoencapsulation effectively protected resveratrol from photodegradation, and MTT assays demonstrated that neither resveratrol nor lipid nanoparticles adversely affected cell viability and integrity of Caco-2 cell monolayers. The in vitro intestinal permeability of resveratrol was significantly increased by NLCs, and SLNs did not impair the absorption of resveratrol. Resveratrol oral absorption can be enhanced during meals, since the intestinal permeability was increased in the presence of fed-state intestinal juices. SLNs and NLCs constitute carrier systems for resveratrol oral administration, for further use as supplements or nutraceuticals.
In gram-positive bacteria, the transcriptional regulator CcpA is at the core of catabolite control mechanisms. In the human pathogen Streptococcus pneumoniae, links between CcpA and virulence have ...been established, but its role as a master regulator in different nutritional environments remains to be elucidated. Thus, we performed whole-transcriptome and metabolic analyses of S. pneumoniae D39 and its isogenic ccpA mutant during growth on glucose or galactose, rapidly and slowly metabolized carbohydrates presumably encountered by the bacterium in different host niches. CcpA affected the expression of up to 19% of the genome covering multiple cellular processes, including virulence, regulatory networks and central metabolism. Its prevalent function as a repressor was observed on glucose, but unexpectedly also on galactose. Carbohydrate-dependent CcpA regulation was also observed, as for the tagatose 6-phosphate pathway genes, which were activated by galactose and repressed by glucose. Metabolite analyses revealed that two pathways for galactose catabolism are functionally active, despite repression of the Leloir genes by CcpA. Surprisingly, galactose-induced mixed-acid fermentation apparently required CcpA, since genes involved in this type of metabolism were mostly under CcpA-repression. These findings indicate that the role of CcpA extends beyond transcriptional regulation, which seemingly is overlaid by other regulatory mechanisms. In agreement, CcpA influenced the level of many intracellular metabolites potentially involved in metabolic regulation. Our data strengthen the view that a true understanding of cell physiology demands thorough analyses at different cellular levels. Moreover, integration of transcriptional and metabolic data uncovered a link between CcpA and the association of surface molecules (e.g. capsule) to the cell wall. Hence, CcpA may play a key role in mediating the interaction of S. pneumoniae with its host. Overall, our results support the hypothesis that S. pneumoniae optimizes basic metabolic processes, likely enhancing in vivo fitness, in a CcpA-mediated manner.
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