Flow field-flow fractionation-inductively coupled optical emission spectrometric investigation of the size-based distribution of iron complexed to phytic and tannic acids in a food suspension: implications for iron availability

Antioxidant Nanoparticles for Concerted Inhibition of α-Synuclein Fibrillization, and Attenuation of Microglial Intracellular Aggregation and Activation

Parkinson’s Disease is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, the extracellular accumulation of toxic α-synuclein (αSYN) aggregates, and neuroinflammation. Microglia, resident macrophages of the brain, are one of the critical cell types involved in neuroinflammation. Upon sensing extracellular stimuli or experiencing oxidative stress, microglia become activated, which further exacerbates neuroinflammation. In addition, as the first line of defense in the central nervous system, microglia play a critical role in αSYN clearance and degradation. While the role of microglia in neurodegenerative pathologies is widely recognized, few therapeutic approaches have been designed to target both microglial activation and αSYN aggregation. Here, we designed nanoparticles (NPs) to deliver aggregation-inhibiting antioxidants to ameliorate αSYN aggregation and attenuate activation of a pro-inflammatory microglial phenotype. Ferulic acid diacid with an adipic acid linker (FAA) and tannic acid (TA) were used as shell and core molecules to form NPs via flash nanoprecipitation. These NPs showed a strong inhibitory effect on αSYN fibrillization, significantly diminishing αSYN fibrillization in vitro compared to untreated αSYN using a Thioflavin T assay. Treating microglia with NPs decreased overall αSYN internalization and intracellular αSYN oligomer formation. NP treatment additionally lowered the in vitro secretion of pro-inflammatory cytokines TNF-α and IL-6, and also attenuated nitric oxide and reactive oxygen species production induced by αSYN. NP treatment also significantly decreased Iba-1 expression in αSYN-challenged microglia and suppressed nuclear translocation of nuclear factor kappa B (NF-κB). Overall, this work lays the foundation for an antioxidant-based nanotherapeutic candidate to target pathological protein aggregation and neuroinflammation in neurodegenerative diseases.

Considerations for the Use of Polyphenols as Therapies in Neurodegenerative Diseases

Over the last two decades, the increase in the incidence of neurodegenerative diseases due to the increasingly ageing population has resulted in a major social and economic burden. At present, a large body of literature supports the potential use of functional nutrients, which exhibit potential neuroprotective properties to mitigate these diseases. Among the most studied dietary molecules, polyphenols stand out because of their multiple and often overlapping reported modes of action. However, ambiguity still exists as to the significance of their influence on human health. This review discusses the characteristics and functions of polyphenols that shape their potential therapeutic actions in neurodegenerative diseases while the less-explored gaps in knowledge of these nutrients will also be highlighted.

Salivary proline-rich protein may reduce tannin-iron chelation: a systematic narrative review

Background

Tannins are often cited for antinutritional effects, including chelation of non-heme iron. Despite this, studies exploring non-heme iron bioavailability inhibition with long-term consumption have reported mixed results. Salivary proline-rich proteins (PRPs) may mediate tannin-antinutritional effects on non-heme iron bioavailability.

Aim

To review evidence regarding biochemical binding mechanisms and affinity states between PRPs and tannins, as well as effects of PRPs on non-heme iron bioavailability with tannin consumption in vivo.

Methods

Narrative systematic review and meta-analysis. Common themes in biochemical modeling and affinity studies were collated for summary and synthesis; data were extracted from in vivo experiments for meta-analysis.

Results

Thirty-two studies were included in analysis. Common themes that positively influenced tannin-PRP binding included specificity of tannin-PRP binding, PRP and tannin stereochemistry. Hydrolyzable tannins have different affinities than condensed tannins when binding to PRPs. In vivo, hepatic iron stores and non-heme iron absorption are not significantly affected by tannin consumption (d = −0.64-1.84; −2.7-0.13 respectively), and PRP expression may increase non-heme iron bioavailability with tannin consumption.

Conclusions

In vitro modeling suggests that tannins favor PRP binding over iron chelation throughout digestion. Hydrolyzable tannins are not representative of tannin impact on non-heme iron bioavailability in food tannins because of their unique structural properties and PRP affinities. With tannin consumption, PRP production is increased, and may be an initial line of defense against tannin-non-heme iron chelation in vivo. More research is needed to compare competitive binding of tannin-PRP to tannin-non-heme iron complexes, and elucidate PRPs’ role in adaption to non-heme iron bioavailability in vivo.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-017-0197-z) contains supplementary material, which is available to authorized users.

Recent Advances in Anticancer Activities and Drug Delivery Systems of Tannins

Tannins, polyphenols in medicinal plants, have been divided into two groups of hydrolysable and condensed tannins, including gallotannins, ellagitannins, and (-)-epigallocatechin-3-gallate (EGCG). Potent anticancer activities have been observed in tannins (especially EGCG) with multiple mechanisms, such as apoptosis, cell cycle arrest, and inhibition of invasion and metastases. Furthermore, the combinational effects of tannins and anticancer drugs have been demonstrated in this review, including chemoprotective, chemosensitive, and antagonizing effects accompanying with anticancer effect. However, the applications of tannins have been hindered due to their poor liposolubility, low bioavailability, off-taste, and shorter half-life time in human body, such as EGCG, gallic acid, and ellagic acid. To tackle these obstacles, novel drug delivery systems have been employed to deliver tannins with the aim of improving their applications, such as gelatin nanoparticles, micelles, nanogold, liposomes, and so on. In this review, the chemical characteristics, anticancer properties, and drug delivery systems of tannins were discussed with an attempt to provide a systemic reference to promote the development of tannins as anticancer agents.

Multivariate data reduction and discrimination of black and green teas due to the physical fractionation pattern of selected metals determined in their infusions

An analytical scheme for the physical fractionation of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Sr and Zn in black and green teas infusions was proposed. It was based on the ultrafiltration/centrifugation through five membranes having molecular weight cut-offs of 100, 50, 30, 10 and 5kDa. The concentrations of the studied metals in the highest and the lowest molecular weight fractions were found to classify and discriminate the analyzed teas infusions much better than the total metals concentrations. The differences in the physical fractionation patterns of these metals assessed for both tea varieties was profound and let to simply classify the infusions of different black and green teas by principal component analysis and linear discriminant analysis.

Review: The potential of the common bean (Phaseolus vulgaris) as a vehicle for iron biofortification

Common beans are a staple food and the major source of iron for populations in Eastern Africa and Latin America. Bean iron concentration is high and can be further increased by biofortification. A major constraint to bean iron biofortification is low iron absorption, attributed to inhibitory compounds such as phytic acid (PA) and polyphenol(s) (PP). We have evaluated the usefulness of the common bean as a vehicle for iron biofortification. High iron concentrations and wide genetic variability have enabled plant breeders to develop high iron bean varieties (up to 10 mg/100 g). PA concentrations in beans are high and tend to increase with iron biofortification. Short-term human isotope studies indicate that iron absorption from beans is low, PA is the major inhibitor, and bean PP play a minor role. Multiple composite meal studies indicate that decreasing the PA level in the biofortified varieties substantially increases iron absorption. Fractional iron absorption from composite meals was 4%–7% in iron deficient women; thus the consumption of 100 g biofortified beans/day would provide about 30%–50% of their daily iron requirement. Beans are a good vehicle for iron biofortification, and regular high consumption would be expected to help combat iron deficiency (ID).