The Role of Antioxidants in Human Health

Restraint stress alters immune parameters and induces oxidative stress in the mouse uterus during embryo implantation

The influence of stress on embryo implantation is not well understood. Prior studies have focused on later gestational stages and the long-term impact of stress on immune function. The objective of this study is to investigate the effects of restraint stress on the immune parameters and the oxidative states of the uterus during implantation. In this study, pregnant CD1 mice were subjected to restraint stress (4 h/d) on embryonic day 1 (E1) and sacrificed on E3, E5, and E7. Maternal plasma corticosterone (CORT) secretion and implantation sites in the uterus were examined. The uterine (excluding embryos) homogenate and uterine lymphocytes were collected to examine oxidative stress states and associated immune parameters. The results demonstrated that restraint stress increased maternal plasma CORT secretion and reduced the number of implantation sites by 15.3% on E5 and by 26.1% on E7. Moreover, restraint stress decreased the density of uterine natural killer (uNK) cells in the endometrium by 22.1-47.9% and increased the density of mast cells in the myometrium by 55.6-76.9%. Restraint stress remarkably decreased the CD3(+)CD4(+) T/CD3(+)CD8(+) T cell ratio (by 26.2-28.9%) and attenuated uterine lymphocyte proliferation and secretion of cytokines. In addition, restraint stress threatened the intracellular equilibrium between oxidants and antioxidants, resulting in decreased glutathione peroxidase (GSH-PX) (32.2% and 45.7%), superoxide dismutase (SOD) (15.5% and 26.1%), and total antioxidant capacity (T-AOC) (18.4% and 18.2%) activities and increased malondialdehyde (MDA) (34.4% and 43.0%) contents on E5 and E7. In conclusion, these findings demonstrate that restraint stress causes abnormal implantation and negatively impacts immune parameters in association with oxidative stress in mice.

A foundation for provitamin A biofortification of maize: genome-wide association and genomic prediction models of carotenoid levels

Efforts are underway for development of crops with improved levels of provitamin A carotenoids to help combat dietary vitamin A deficiency. As a global staple crop with considerable variation in kernel carotenoid composition, maize (Zea mays L.) could have a widespread impact. We performed a genome-wide association study (GWAS) of quantified seed carotenoids across a panel of maize inbreds ranging from light yellow to dark orange in grain color to identify some of the key genes controlling maize grain carotenoid composition. Significant associations at the genome-wide level were detected within the coding regions of zep1 and lut1, carotenoid biosynthetic genes not previously shown to impact grain carotenoid composition in association studies, as well as within previously associated lcyE and crtRB1 genes. We leveraged existing biochemical and genomic information to identify 58 a priori candidate genes relevant to the biosynthesis and retention of carotenoids in maize to test in a pathway-level analysis. This revealed dxs2 and lut5, genes not previously associated with kernel carotenoids. In genomic prediction models, use of markers that targeted a small set of quantitative trait loci associated with carotenoid levels in prior linkage studies were as effective as genome-wide markers for predicting carotenoid traits. Based on GWAS, pathway-level analysis, and genomic prediction studies, we outline a flexible strategy involving use of a small number of genes that can be selected for rapid conversion of elite white grain germplasm, with minimal amounts of carotenoids, to orange grain versions containing high levels of provitamin A.

The discovery and development of new potential antioxidant agents for the treatment of neurodegenerative diseases

INTRODUCTION

Several neurodegenerative disorders (NDs) including Alzheimer's and Huntington's diseases have had associations with the oxidative process and free radical damage. Consequently, in past decades, several natural and synthetic antioxidants have been assessed as therapeutic agents but have shown limitations in bioavailability, metabolic susceptibility and permeability to the blood brain barrier. Given these issues, medicinal chemists are hard at work to modify/improve the chemical structures of these antioxidants, thereby improving their efficacy.

AREAS COVERED

In this review, the authors critically analyze several biological mechanisms involved in the generation of free radicals. Additionally, they analyze free radicals' role in the generation of oxidative stress and in the progression of many NDs. Further, the authors review a collection of natural and synthetic antioxidants, their role as free radical scavengers along with their mechanisms of action and their potential for preventing neurodegenerative diseases.

EXPERT OPINION

So far, preclinical studies on several antioxidants have shown promise for treating NDs, despite their limitations. The authors do highlight the lack of the adequate animal models for preclinical assessment and this does hinder further progression into clinical trials. Further studies are necessary to fully investigate the potential of these antioxidants as ND therapeutic options.

Cisplatin-induced nephrotoxicity in mice: protective role of Leea asiatica leaves

Cisplatin is a popular anticancer drug, but its side effects like nephrotoxicity and hepatotoxicity due to oxidative stress limited its clinical use. In tis study, nephoprotective effect of fractions of Leea asiatica (Leeaceae) leaves was assessed against cisplatin induced toxicity in rats. Leaves of L. asiatica extracted with methanol, ethyl acetate, petroleum ether, and evaluated for in vitro and ex vivo antioxidant activity using several assay models. Methanol extract showed better antioxidant effects, and contain higher amount of phenolic (77.75 ± 0.87 mg GAE/g of dry material) and flavonoid compound (60.98 ± 0.58 mg QE/g of dry material) compared with other extracts. Hance methanol extract was selected for further investigation and fractionated with methanol, ethyl acetate, petroleum ether. Protective effect of methanol extract and its fractions was evaluated against cisplatin (20 mg/kg, i.p.) induced nephrotoxicity. Pretreatment with methanol extract (150 and 300 mg/kg), and its fractions especially methanol, ethyl acetate fraction (75 and 150 mg/kg) significantly reduced blood urea nitrogen, serum creatinine, uric acid levels, and decreased malondialdehyde level and increase total protein and albumin level (p < 0.05, 0.01). Ethyl acetate fraction produced highest nephroprotective, possibly by inhibiting lipid peroxidation process. Result suggested that ethyl acetate fraction possesses potent nephroprotective activity and can be used an adjunct therapy aiming to improve the effectiveness of several nephrotoxic drugs.

Anthelmintic and in vitro antioxidant evaluation of fractions of methanol extract of Leea asiatica leaves

Leea asiatica, a folk medicinal plant of India, is used in the treatment of worm infection and other oxidative stress-related disorders, traditionally. In the present study, the in vitro anthelmintic and in vitro antioxidant activity of different fractions of the methanol extract from the Leea asiatica leaves were evaluated. The fraction displayed significant anthelmintic activity against Indian adult earthworms (Pheretima posthuma). The ethyl acetate fraction showed a better paralysis activity (13.99 ± 0.59), while the methanol fraction showed a better death time (63.76 ± 0.73 minutes), when compared with other fractions, at a dose of 50 mg/ml concentration. The anthelmintic activity of methanol and the ethyl acetate fraction were almost similar and comparable to the standard drug, piperazine citrate. The petroleum ether fraction did not produce a potent anthelmintic effect compared to the standard. The in vitro antioxidant activity was evaluated by using the diphenyl-picrylhydrazyl (DPPH) radical scavenging assay, nitric oxide radical scavenging assay, lipid peroxidation assay, and the ferric thiocyanate method. The ethyl acetate fraction showed better antioxidant activity in all tested methods. The IC(50) value of the ethyl acetate fraction in the DPPH radical, nitric oxide radical scavenging assay, and lipid peroxidation assay were 9.5, 13.0, and 57.0 μg/ml, respectively. The fractions significantly (P < 0.05) inhibited the peroxidation of linoleic acid. The results confirmed the folk use of Leea asiatica in warm infection and the plant could be viewed as a potential source of natural anthelmintic and antioxidant compound.