Label-Free Electrochemical Biosensors to Evaluate the Antioxidant Effect of Tocopherol in Ultraviolet Radiation

Lixia Gao, Yong Teng

Methods Mol Biol . 2022;2343:241-246. doi: 10.1007/978-1-0716-1558-4_16.

Abstract

Electrochemical biosensors offer a sensitive, specific, and rapid detection platform for in situ real-time monitoring of intracellular and extracellular metabolites. These sensors have been widely used to evaluate the efficacy of preclinical drugs, especially for natural products with antioxidant potency. Ultraviolet (UV) radiation causes oxidative stress in cells and induces cells to release reactive oxygen species. Tocopherol is a fat-soluble vitamin found in vegetable oils as well as in grains, seeds, and nuts, which plays an important protective role as an antioxidant in resisting oxidative stress caused by UV radiation. Here, we describe a protocol using a glass carbon electrode functionalized with nanotube@DNA-Mn₃(PO₄)2 composite to monitor and quantify the production of superoxide ions in UV-irradiated melanoma cells in the presence or absence of tocopherol. This study demonstrates the advantages and potential application of label-free electrochemical sensors in the measurement of natural antioxidants from plant materials.

R Scott Duncan, Daniel T Hurtado, Conner W Hall, Peter Koulen

Front Pharmacol . 2022 Jan 4;12:798938. doi: 10.3389/fphar.2021.798938. eCollection 2021.

Abstract

The purpose of this study was to determine if different vitamin E components exhibit similar efficacy and mechanism of action in protecting Retinal pigment epithelium (RPE) cells from oxidative damage. We hypothesized that α-tocopherol (αT) is unique among vitamin E components in its cytoprotective mechanism of action against oxidative stress in RPE cells and that it requires protein synthesis for optimal antioxidant effect. We used cell viability assays, fluorescent chemical labeling of DNA and actin and immuno-labeling of the antioxidant proteins Nrf2 and Sod2 and of the tight junction protein, ZO-1, and confocal microscopy to determine the effects of αT and γT against oxidative stress in immortalized human RPE cells (hTERT-RPE). Using the four main vitamin E components, αT, γT, δ-tocopherol (δT) and α-tocotrienol (αTr), we ascertained that they exhibit similar, but not identical, antioxidant activity as αT when used at equimolar concentrations. In addition, we determined that the exposure time of RPE cells to α-tocopherol is critical for its ability to protect against oxidative damage. Lastly, we determined that αT, but not γT, partially requires the synthesis of new proteins within a 24-h period and prior to exposure to tBHP for optimal cytoprotection. We conclude that, unlike γT and δT, αT appears to be unique in its requirement for transport and/or signaling for it to be an effective antioxidant. As a result, more focus should be paid to which vitamin E components are used for antioxidant interventions.

Mohadeseh Ahmadi, Akbar Hedayatizadeh-Omran, Reza Alizadeh-Navaei, Majid Saeedi, Ehsan Zaboli, Omolbanin Amjadi, Hamidreza Kelidari, Zahra Besharat

Asian Pac J Cancer Prev . 2022 Jan 1;23(1):201-205. doi: 10.31557/APJCP.2022.23.1.201.

Abstract

Objective: This study aimed to evaluate in vitro synergistic anticancer effect of doxorubicin combined with Vitamin E.

Methods: The MTT assay was utilized to assess the cytotoxicity of Vitamin E and vitamin E combined with doxorubicin and vital activities of SKBR3, MDA-MB-231, and HFF cells over a 24-hour incubation period. In addition, the antioxidant properties of these interventions and the decrease of reactive oxygen species (ROS) content caused by the treatment were evaluated.

Results: The antiproliferative effect of doxorubicin increased significantly in combination with vitamin E (Doxcorobicin 2µM vs. Vitamin E 120µM, P=0.000). Despite reducing cell ROS content due to vitamin E treatment, the combination of vitamin E and doxorubicin showed no significant synergistic effect (Doxcorobicin 2µM vs. Vitamin E 120µM, P=0.998).

Conclusion: This study indicated that the doxorubicin-vitamin E treatment reduced the viability of breast cancer cells with the minimum side effects on normal cells. In addition, the high dosage of vitamin E intensified the cytotoxicity of doxorubicin.

Eka Roina Megawati, Lokot Donna Lubis, Febi Yanti Harahap

Folia Med (Plovdiv) . 2021 Dec 31;63(6):895-900. doi: 10.3897/folmed.63.e57877

Abstract

Introduction: Obesity creates health problems by increasing the risks of chronic diseases such as type 2 diabetes and cardiovascular disorders. Obesity leads to insulin resistance, higher blood glucose and cholesterol levels. Adipose tissues synthesize adiponectin which acts as anti-inflammatory, antidiabetic, and anti-atherogenic agent. Meanwhile, vitamin E is an antioxidant that acts as an anti-inflammation.

Aim: The purpose of this study was to analyze the effects of vitamin E supplementation to metabolic markers on diet-induced obesity in mice.

Materials and methods: Twenty-four mice (Mus musculus, L) aged four weeks were divided into six groups which were fed different diets and given vitamin E in different dosages or methods. The period of treatment was 18 weeks. The mice body weights were measured every week; blood sugar and cholesterol levels were measured every six weeks, and the adiponectin level measurement was done at week 18.

Results: A repeated measures ANOVA showed that body weight and cholesterol level within groups were not significantly different [F(15, 54)=1.417, 0.173 and F(10, 36)=1.391, 0.224 respectively]. The glucose levels were found to be significantly different [F(7.646, 27.526)=2.625, 0.030]. There was no significant difference in the adiponectin levels.

Conclusions: Vitamin E supplementation could not prevent the increase of body weight, the elevation of blood sugar and cholesterol levels, and also could not increase adiponectin level.

Muntaha S Al-Khdour, Omar F Khabour, Laith N Al-Eitan, Karem H Alzoubi

Drug Chem Toxicol . 2021 Dec 29;1-5. doi: 10.1080/01480545.2021.2015369. Online ahead of print.

Abstract

Nedaplatin is a chemotherapeutic agent used widely in cancer therapy. Nedaplatin has been shown to cause DNA damage to cells via the induction of oxidative stress. Vitamin E (Vit E) has an anti-mutagenic activity that can protect cells from DNA damaging agents. The objective of this study is to examine the genotoxic and cytotoxic effects of nedaplatin in human cultured lymphocytes. In addition, modulation of such effects by Vit E was also examined. The frequencies of sister chromatid exchange (SCE) and chromosomal aberrations (CAs) were used as an indicator for genotoxicity. The mitotic and proliferative indices were used to examine the cytotoxic effects of nedaplatin. The results showed that nedaplatin significantly elevated SCE and CA frequencies in human lymphocytes (p ˂ 0.01). The increases in the frequencies of SCE and CA caused by nedaplatin were lowered by pretreatment treatment with Vit E (p < 0.05). Nedaplatin significantly lowered mitotic index but Vit E pretreatment did not modulate this effect. These results suggest that Vit E has the potential to ameliorate the genotoxicity of nedaplatin in cultured lymphocytes.

Kasthuri Bai Magalingam, Sushela Devi Somanath, Shadab Md, Nagaraja Haleagrahara, Ju-Yen Fu, Kanga Rani Selvaduray, Ammu Kutty Radhakrishnan

Nutr Res . 2021 Dec 28;98:27-40. doi: 10.1016/j.nutres.2021.09.003. Online ahead of print.

Abstract

Oxidative stress is a critical factor that triggers a “domino” cascade of events leading to the degeneration of dopaminergic neurons in Parkinson disease. Tocotrienols (T3) have antioxidant effects and can protect neuronal cells against oxidative damage. In the present study, we investigated the neuroprotective effects of different forms of T3 (alpha, delta, gamma) or tocotrienol-rich fraction (TRF) against 6-hydroxydopamine (6-OHDA)-induced oxidative damage in differentiated SH-SY5Y human neural cells. Differentiating the SH-SY5Y cells with retinoic acid and a low-serum culture medium for 6 days allowed development of human dopamine-like neural cells. Subsequently, the differentiated SH-SY5Y neural cells were pretreated with different forms of T3 for 24 hours before these cells were exposed to 6-OHDA. The T3 analogues and TRF displayed neuroprotective effects (P < .05) via restoration of cell viability and activation of antioxidant enzymes (e.g., superoxide dismutase, catalase). Notably, TRF was highly efficient in scavenging reactive oxygen species and upregulating dopamine and tyrosine hydroxylase levels in the differentiated SH-SY5Y cells. Gamma-T3 exhibited the most potent effects in attenuating apoptosis, whereas alpha-T3 was most effective in preventing 6-OHDA-induced leakage of α-Synuclein. Delta-T3 displayed a noticeable effect in upregulating the dopamine receptor D2 gene expression compared with controls. These findings suggest T3 isoforms and TRF demonstrate significant neuroprotective effects in protecting differentiated neural cells against 6-OHDA-mediated oxidative stress.

Lucas S Moreira, Any Carolina Chagas, Ana Paula Ames-Sibin, Vanesa O Pateis, Odinei H Gonçalves, Francielli Maria S Silva-Comar, Luzmarina Hernandes, Anacharis B Sá-Nakanishi, Lívia Bracht, Ciomar A Bersani-Amado, Adelar Bracht, Jurandir F Comar

J Tradit Complement Med . 2021 Dec 24;12(4):414-425. doi: 10.1016/j.jtcme.2021.12.003. eCollection 2022 Jul.

Abstract

Background and aim: The present study investigated the effects of orally administered α-tocopherol-loaded polycaprolactone nanoparticles on the articular inflammation and systemic oxidative status of middle-aged Holtzman rats with Freund’s adjuvant-induced polyarthritis, a model for rheumatoid arthritis. Intraperitoneally administered free α-tocopherol provided the reference for comparison.

Experimental procedure: Two protocols of treatment were followed: intraperitoneal administration of free α-tocopherol (100 mg/kg i.p.) or oral administration of free and nanoencapsulated α-tocopherol (100 mg/kg p.o.). Animals were treated during 18 days after arthritis induction.

Results: Free (i.p.) and encapsulated α-tocopherol decreased the hind paws edema, the leukocytes infiltration into femorotibial joints and the mRNA expression of pro-inflammatory cytokines in the tibial anterior muscle of arthritic rats, but the encapsulated compound was more effective. Free (i.p.) and encapsulated α-tocopherol decreased the high levels of reactive oxygen species in the brain and liver, but only the encapsulated compound decreased the levels of protein carbonyl groups in these organs. Both free (i.p.) and encapsulated α-tocopherol increased the α-tocopherol levels and the ratio of reduced to oxidized glutathione in these organs.

Conclusion: Both intraperitoneally administered free α-tocopherol and orally administered encapsulated α-tocopherol effectively improved inflammation and systemic oxidative stress in middle-aged arthritic rats. However, the encapsulated form should be preferred because the oral administration route does not be linked to the evident discomfort that is caused in general by injectable medicaments. Consequently, α-tocopherol-loaded polycaprolactone nanoparticles may be a promising adjuvant to the most current approaches aiming at rheumatoid arthritis therapy.

Chwan-Li Shen, Huanbiao Mo, Dale M Dunn, Bruce A Watkins

Front Nutr . 2021 Dec 24;8:766711. doi: 10.3389/fnut.2021.766711. eCollection 2021.

Abstract

Osteoporosis is a major health problem in postmenopausal women. Herein we evaluated the effects of 12-week tocotrienols (TT) supplementation on serum metabolites in postmenopausal, osteopenic women. Eighty-nine participants (59.7 ± 6.8 yr, BMI 28.7 ± 5.7 kg/m²) were assigned to 3 treatments: placebo (860 mg olive oil/day), 300mg TT (300 mg TT/day), and 600mg TT (600 mg TT/day) for 12 weeks. TT consisted of 90% δ-TT and 10% γ-TT. In this metabolomic study, we evaluated the placebo and 600mgTT at baseline and 12 weeks. As expected, TT and its metabolite levels were higher in the supplemented group after 12 weeks. At baseline, there were no differences in demographic parameters or comprehensive metabolic panels (CMP). Metabolomics analysis of serum samples revealed that 48 biochemicals were higher and 65 were lower in the 600mg TT group at 12 weeks, compared to baseline. The results confirmed higher serum levels of tocotrienols and lysophospholipids, but lower acylcarnitines and catabolites of tryptophan and steroids in subjects given 600mg TT. In summary, 12-week TT supplementation altered many serum metabolite levels in postmenopausal women. The present study supports our previous findings that TT supplementation helps reduce bone loss in postmenopausal osteopenic women by suppressing inflammation and oxidative stress. Furthermore, the body incorporates TT which restructures biomembranes and modifies phospholipid metabolism, a response potentially linked to reduced inflammation and oxidative stress.

Grazyna Nowak, Judit Megyesi

Int J Mol Sci . 2021 Nov 24;22(23):12674. doi: 10.3390/ijms222312674.

Abstract

Ischemia-induced mitochondrial dysfunction and ATP depletion in the kidney result in disruption of primary functions and acute injury of the kidney. This study tested whether γ-tocotrienol (GTT), a member of the vitamin E family, protects mitochondrial function, reduces ATP deficits, and improves renal functions and survival after ischemia/reperfusion injury. Vehicle or GTT (200 mg/kg) were administered to mice 12 h before bilateral kidney ischemia, and endpoints were assessed at different timepoints of reperfusion. GTT treatment reduced decreases in state 3 respiration and accelerated recovery of this function after ischemia. GTT prevented decreases in activities of complexes I and III of the respiratory chain, and blocked ischemia-induced decreases in F₀F₁-ATPase activity and ATP content in renal cortical tissue. GTT improved renal morphology at 72 h after ischemia, reduced numbers of necrotic proximal tubular and inflammatory cells, and enhanced tubular regeneration. GTT treatment ameliorated increases in plasma creatinine levels and accelerated recovery of creatinine levels after ischemia. Lastly, 89% of mice receiving GTT and 70% of those receiving vehicle survived ischemia. Conclusions: Our data show novel observations that GTT administration improves mitochondrial respiration, prevents ATP deficits, promotes tubular regeneration, ameliorates decreases in renal functions, and increases survival after acute kidney injury in mice.

Juan Riestra-Ayora, Carolina Sánchez-Rodríguez, Raquel Palao-Suay, Joaquín Yanes-Díaz, Ana Martín-Hita, María Rosa Aguilar, Ricardo Sanz-Fernández

Drug Deliv . 2021 Dec;28(1):1376-1388. doi: 10.1080/10717544.2021.1923863.

Abstract

The prognosis of patients with recurrent or metastatic head and neck squamous cell cancer (HNSCC) is generally poor. New treatments are required to supplement the current standard of care. Paclitaxel (PTX), an effective chemotherapeutic for HNSCC, has serious side effects. A polymeric nanocarrier system was developed for the delivery of PTX to improve HNSCC treatment. This study aimed to evaluate the antitumor efficacy of PTX-loaded polymeric nanoparticles based on α-TOS (PTX-NPs) administered by direct intratumoral injection into a Hypopharynx carcinoma squamous cells (FaDu) tumor xenograft mouse model. The nanocarrier system based on block copolymers of polyethylene glycol (PEG) and a methacrylic derivative of α-TOS was synthesized and PTX was loaded into the delivery system. Tumor volume was measured to evaluate the antitumor effect of the PTX-NPs. The relative mechanisms of apoptosis, cell proliferation, growth, angiogenesis, and oxidative and nitrosative stress were detected by Western blotting, fluorescent probes, and immunohistochemical analysis. The antitumor activity results showed that compared to free PTX, PTX-NPs exhibited much higher antitumor efficacy and apoptosis-inducing in a FaDu mouse xenograft model and demonstrated an improved safety profile. Ki-67, EGFR, and angiogenesis markers (Factor VIII, CD31, and CD34) expression were significantly lower in the PTX-NPs group compared with other groups (p < .05). Also, PTX-NPs induced oxidative and nitrosative stress in tumor tissue. Direct administration of PTX-loaded polymeric nanoparticles based on α-Tocopheryl Succinate at the tumor sites, proved to be promising for HNSCC therapy.