Evaluation of Resveratrol and Piceatannol Cytotoxicity in Macrophages, T Cells, and Skin Cells

Optimizing the Preparation of Silk Fibroin Nanoparticles and Their Loading with Polyphenols: Towards a More Efficient Anti-Inflammatory Effect on Macrophages

Silk fibroin nanoparticles (SFN) have become a promising tool in drug delivery systems due to their physicochemical characteristics. SFN have shown their outstanding properties as an active vehicle for polyphenols, enhancing their antioxidant and anti-inflammatory effects on macrophages; therefore, it becomes necessary to have an easy, reproducible and scalable production method. In order to improve the production of nanoparticles, we performed direct precipitation of non-dialyzed silk fibroin solutions and evaluated the reproducibility of the method using dynamic light scattering. We also studied the loading efficiency of three different natural polyphenols using propylene glycol as a solvent. The loaded nanoparticles were fully characterized and used to treat human macrophage cells to assess the anti-inflammatory activity of these nanoparticles. The measured hydrodynamic characteristics of the SFN and the overall yield of the process showed that the new preparation method is highly reproducible and repeatable. Thus, we not only present a new scalable method to prepare silk nanoparticles but also how to improve the loading of natural polyphenolic compounds to the SFN, as well as the important anti-inflammatory effects of these loaded nanoparticles in a cell model of human macrophage cells.

Emerging Effects of Resveratrol on Wound Healing: A Comprehensive Review

Resveratrol (RSV) is a natural extract that has been extensively studied for its significant anti-inflammatory and antioxidant effects, which are closely associated with a variety of injurious diseases and even cosmetic medicine. In this review, we have researched and summarized the role of resveratrol and its different forms of action in wound healing, exploring its role and mechanisms in promoting wound healing through different modes of action such as hydrogels, fibrous scaffolds and parallel ratio medical devices with their anti-inflammatory, antioxidant, antibacterial and anti-ageing properties and functions in various cells that may play a role in wound healing. This will provide a direction for further understanding of the mechanism of action of resveratrol in wound healing for future research.

Toxicological Evaluation of Piceatannol, Pterostilbene, and ε-Viniferin for Their Potential Use in the Food Industry: A Review

The application of stilbenes in the food industry is being considered because of their biological activities. Piceatannol, pterostilbene and ε-viniferin have awakened the industry’s interest. However, before they can be commercialized, we must first guarantee their safety for consumers. The present work reviews the toxicological studies performed with these stilbenes. A wide variety of studies has demonstrated their cytotoxic effects in both cancer and non-cancerous cell lines. In contrast, although DNA damage was detected by some authors, in vitro genotoxic studies on the effects of piceatannol, pterostilbene, and ε-viniferin remain scarce. None of the three reviewed substances have been evaluated using the in vitro tests required by the European Food Safety Authority (EFSA) as the first step in genotoxicity testing. We did not find any study on the toxic effects of these stilbenes in vivo. Thus, more studies are needed to confirm their safe use before they can be authorized as additive in the food industry.

Potential Adverse Effects of Resveratrol: A Literature Review

Due to its health benefits, resveratrol (RE) is one of the most researched natural polyphenols. Resveratrol's health benefits were first highlighted in the early 1990s in the French paradox study, which opened extensive research activity into this compound. Ever since, several pharmacological activities including antioxidant, anti-aging, anti-inflammatory, anti-cancerous, anti-diabetic, cardioprotective, and neuroprotective properties, were attributed to RE. However, results from the available human clinical trials were controversial concerning the protective effects of RE against diseases and their sequelae. The reason for these conflicting findings is varied but differences in the characteristics of the enrolled patients, RE doses used, and duration of RE supplementation were proposed, at least in part, as possible causes. In particular, the optimal RE dosage capable of maximizing its health benefits without raising toxicity issues remains an area of extensive research. In this context, while there is a consistent body of literature on the protective effects of RE against diseases, there are relatively few reports investigating its possible toxicity. Indeed, toxicity and adverse effects were reported following consumption of RE; therefore, extensive future studies on the long-term effects, as well as the in vivo adverse effects, of RE supplementation in humans are needed. Furthermore, data on the interactions of RE when combined with other therapies are still lacking, as well as results related to its absorption and bioavailability in the human body. In this review, we collect and summarize the available literature about RE toxicity and side effects. In this process, we analyze in vitro and in vivo studies that have addressed this stilbenoid. These studies suggest that RE still has an unexplored side. Finally, we discuss the new delivery methods that are being employed to overcome the low bioavailability of RE.

In Vitro Toxicity Assessment of Stilbene Extract for Its Potential Use as Antioxidant in the Wine Industry

The reduction of sulfur dioxide in wine is a consumer's demand, considering the allergic effects that may occur in people who are sensitive to it. Stilbenes are candidates of great interest for this purpose because of their antioxidant/antimicrobial activities and health properties, and also because they are naturally found in the grapevine. In the present study, the in vitro toxicity of an extract from grapevine shoots (with a stilbene richness of 45.4%) was assessed in two human cell lines. Significant damage was observed from 30 μg/mL after 24 h, and 40 µg/mL after 48 h of exposure. Similarly, the ultrastructural study revealed a significant impairment of cell growing. The extract was able to protect cells against an induced oxidative stress at all concentrations studied. In view of the promising results, a more exhaustive toxicological assessment of the extract is needed to confirm the safety of its further use as additive in wine.

Alpha-mangostin: Anti-inflammatory and antioxidant effects on established collagen-induced arthritis in DBA/1J mice

Rheumatoid arthritis (RA) is an autoimmune disease that causes physical disability in people worldwide. Despite progress made in RA treatment in the past decade, new drugs with high efficacy but few long-term adverse effects are still needed. This study focused on evaluating the therapeutic potential of α-mangostin on established collagen-induced arthritis (CIA) in DBA/1J mice. Arthritic DBA/1J mice were orally administered with two doses of α-mangostin (10 and 40 mg/kg) daily, for 33 days. Alpha-mangostin significantly decreased the clinical score in the short term at both doses and decreased the histopathological score at the higher dose. This improvement was accompanied by a reduction on serum levels of anti-collagen IgG2a autoantibodies and of the production of LIX/CXCL5, IP-10/CXCL10, MIG/CXCL9, RANTES/CCL5, IL-6 and IL-33 in the joints of CIA mice. Alpha-mangostin also exhibited an anti-oxidant effect decreasing the NADPH oxidase activity and lipid peroxidation and preserving the levels of reduced glutathione in the arthritic joints. In vitro this xanthone demonstrated modulatory properties on LPS-activated dendritic cells, although in Th1 and Th17-polarized lymphocytes promotes a pro-apoptotic phenotype. Altogether this study illustrates the capacity of α-mangostin to ameliorate the early clinical and histological signs of established CIA by reducing the inflammatory and oxidative responses.

Evaluation of hypoxia inducible factor targeting pharmacological drugs as antileishmanial agents

OBJECTIVE

To evaluate whether hypoxia inducible factor (HIF-1α) targeting pharmacological drugs, echinomycin, resveratrol and CdCl2 which inhibit HIF-1α stimulation, and mimosine, which enhances the stability of HIF-1α present antileishmanial properties.

METHODS

The leishmanicidal effect of drugs was evaluated in mouse macrophages and Balb/c mouse model for cutaneous leishmaniosis.

RESULTS

Resveratrol and CdCl2 reduced the parasite load [IC50, (27.3 ± 2.25) μM and (24.8 ± 0.95) μM, respectively]. The IC50 value of echinomycin was (22.7 ± 7.36) nM and mimosine did not alter the parasite load in primary macrophages. The macrophage viability IC50 values for resveratrol, echinomycin and CdCl2 and mimosine were >40 μM, >100 nM, >200 μM and>2000 μM, respectively. In vivo no differences between cutaneous lesions from control, resveratrol- and echinomycin-treated Balb/c mice were detected.

CONCLUSIONS

Resveratrol, echinomycin and CdCl2 reduce parasite survival in vitro. The HIF-1α targeting pharmacological drugs require further study to more fully determine their anti-Leishmania potential and their role in therapeutic strategies.

Closer association of mitochondria with lipid droplets in hepatocytes and activation of Kupffer cells in resveratrol-treated senescence-accelerated mice

Resveratrol has been extensively investigated because of its beneficial effects in delaying age-related diseases, thus extending the lifespan, possibly by mimicking calorie restriction. For this study, cell biological techniques were used to examine how resveratrol influenced hepatocytes in a senescence-accelerated mouse P10 (SAMP10), treated from 35 to 55 weeks of age, with special emphasis on the relationship between mitochondria and lipid droplets. Survival ratio, body weight and food intake of SAMP10 did not differ significantly between the control and resveratrol-treated groups. Compared with the control, the treated livers were altered significantly, as follows. Lipid droplets were reduced and mitochondria were increased in number in hepatocytes. Phosphorylation of acetyl-CoA carboxylase and the expression of both the mitochondrial ATP synthase β subunit and Mn superoxide dismutase (SOD2) were increased. Mitochondria, expressing more SOD2, were more tightly associated with lipid droplets, suggesting the enhancement of lipolysis through the activation of mitochondrial functions. Cathepsin D expression was less in hepatocytes but enhanced in Kupffer cells, which were increased in number and size with more numerous lysosome-related profiles. Together, resveratrol may activate mitochondria resulting in consuming lipids, and may also activate Kupffer cells by which a beneficial milieu for hepatocytes may be created. Both might be related to improvement in the functioning of the liver, which is the organ that is central to metabolic regulation.

Effects of flavonoids and other polyphenols on inflammation

Flavonoids are a family of polyphenolic compounds which are widespread in nature (vegetables) and are consumed as part of the human diet in significant amounts. There are other types of polyphenols, including, for example, tannins and resveratrol. Flavonoids and related polyphenolic compounds have significant antiinflammatory activity, among others. This short review summarizes the current knowledge on the effects of flavonoids and related polyphenolic compounds on inflammation, with a focus on structural requirements, the mechanisms involved, and pharmacokinetic considerations. Different molecular (cyclooxygenase, lipoxygenase) and cellular targets (macrophages, lymphocytes, epithelial cells, endothelium) have been identified. In addition, many flavonoids display significant antioxidant/radical scavenging properties. There is substantial structural variation in these compounds, which is bound to have an impact on their biological profile, and specifically on their effects on inflammatory conditions. However, in general terms there is substantial consistency in the effects of these compounds despite considerable structural variations. The mechanisms have been studied mainly in myeloid cells, where the predominant effect is an inhibition of NF-κB signaling and the downregulation of the expression of proinflammatory markers. At present there is a gap in knowledge of in vitro and in vivo effects, although the pharmacokinetics of flavonoids has advanced considerably in the last decade. Many flavonoids have been studied for their intestinal antiinflammatory activity which is only logical, since the gastrointestinal tract is naturally exposed to them. However, their potential therapeutic application in inflammation is not restricted to this organ and extends to other sites and conditions, including arthritis, asthma, encephalomyelitis, and atherosclerosis, among others.

Microglia of rat ventral midbrain recovers its resting state over time in vitro: let microglia rest before work

Cortical or total brain cultures of microglia are commonly used as a model to study the inflammatory processes in Parkinson's disease. Here we characterize microglia cultures from rat ventral midbrain and evaluate their response to zymosan A. We used specific markers of microglia and evaluated the morphology, the phagocytic activity and reactive oxygen species (ROS) levels of the cells. During the first 10 days in vitro (DIV), cultures presented predominantly cells with a round morphology, expressing CD68 and with high phagocytic activity and ROS production. After 13 DIV, this tendency was reversed, with cultures showing higher number of ramified cells and fewer CD68(+) cells along with lower phagocytic and ROS production capability, suggesting that microglia must be kept in vitro for at least 13 days to recover its resting state. The exposure of cultures with less than 10 DIV to zymosan A significantly decreased cell viability. Exposure of cultures with 13 DIV to zymosan A (0.05, 0.5, or 5 microg/ml) increased the total cell number, the percentage of CD68(+) cells, and the phagocytic activity. Concentrations of zymosan A higher than 5 microg/ml were also effective in activating microglia but significantly decreased the number of viable cells. In summary, microglial cells remain in the activated state for several days after the isolation process and, thus, stimulation of microglia recently isolated can compromise interpretation of the results. However, upon 13 DIV, cells achieve properties of nonactivated microglia and present a characteristic response to a proinflammatory agent.

In vitro evaluation of the cytotoxic and anti-proliferative properties of resveratrol and several of its analogs

Resveratrol (RES), a component of red wine, possesses anti-inflammatory properties. The studies described in the present work were aimed at evaluating the potential for RES and related stilbene analogs (piceatannol, PIC; pterostilbene, TPS; trans-stilbene, TS; and trans-stilbene oxide, TSO) to exhibit toxicity towards RAW 264.7 mouse macrophages. The effect of TS, TSO, RES and TPS on RAW 264.7 macrophage viability was determined by two standard methods: (a) the MTT assay and (b) the trypan blue dye exclusion test. Whereas macrophages were more sensitive to PIC (LC_{50 trypan} ∼ 1.3 μM) and to TPS (LC_{50 trypan} ∼ 4.0 μM and LC_{50 MTT} ∼ 8.3 μM) than to RES (LC_{50 trypan} ∼ 8.9 μM and LC_{50 MTT} ∼ 29.0 μM), they were relatively resistant to TSO (LC_{50 trypan} ∼ 61.0 μM and LC_{50 MTT} > 100 μM) and to TS (LC_{50 trypan} ≥ 5.0 μM and LC_{50 MTT} ≥ 5.0 μM). The ability of selected stilbenes (RES, TPS and PIC) to exhibit growth inhibitory effects was also examined. Although RES and TPS were observed to inhibit cell proliferation in macrophages (IC₅₀ ≤ 25 μM), these cells were resistant to growth inhibition by PIC (IC₅₀ ≥ 50 μM). The data obtained in the present analysis demonstrate that substituted stilbene compounds such as RES have the capacity to exhibit cytotoxic and anti-proliferative activities in macrophages.