Concentration Dependence of the Antioxidant and Prooxidant Activity of Trolox in HeLa Cells: Involvement in the Induction of Apoptotic Volume Decrease

Maria Elena Giordano, Roberto Caricato, Maria Giulia Lionetto

Antioxidants (Basel) . 2020 Oct 29;9(11):E1058. doi: 10.3390/antiox9111058.

Abstract

Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), a hydrophilic analog of vitamin E, is known for its strong antioxidant activity, being a high radical scavenger of peroxyl and alkoxyl radicals. Under particular conditions, Trolox may also exhibit prooxidant properties. The present work aimed at studying the dual antioxidant/prooxidant behavior of Trolox over a wide range of concentrations (from 2.5 to 160 µM) in HeLa cells. In particular, the study addressed the dose-dependent effects of Trolox on the oxidative cell status and vitality of HeLa cells, focusing on the potential role of the vitamin E analog in the induction of one of the first steps of the apoptotic process, Apoptotic Volume Decrease (AVD). In HeLa cells, Trolox showed significant antioxidant activity, expressed as the ability to reduce the endogenous ROS production detected by the ROS-sensitive probe 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate (CM-H₂DCFDA), at low concentrations (range: 2.5-15 µM), but exerted a dose-dependent prooxidant effect at higher concentrations after 24 h exposure. The prooxidant effect was paralleled by the reduction in cell viability due to the induction of the apoptotic process. The dual behavior, antioxidant at lower concentrations and prooxidant at higher concentrations, was evident also earlier after 2 h incubation, and it was paralleled by the isotonic shrinkage of the cells, ascribed to AVD. The use of SITS, known Cl^– channel blocker, was able to completely inhibit the Trolox-induced isotonic cell shrinkage, demonstrating the involvement of the vitamin E analog in the alteration of cell volume homeostasis and, in turn, in the AVD induction. In conclusion, the study shed light on the concentration dependence of the Trolox antioxidant/prooxidant activity in HeLa cells and revealed its role in the induction of one of the first events of apoptosis, AVD, at high concentrations.

Hirokatsu Saito, Kenshiro Hara, Satoshi Kitajima, Kentaro Tanemura

Reprod Toxicol . 2020 Oct 9;S0890-6238(20)30225-2. doi: 10.1016/j.reprotox.2020.10.003. Online ahead of print.

Abstract

Vitamin E (VE) plays numerous important roles in mammals because of its antioxidant activity. As a result, VE deficiency (VED) leads to the dysfunction of central nervous, reproductive, and immune systems. However, few studies have reported the effects of VED on the male reproductive system. In this study, we investigated the effects of VED on male reproductive function and examined its relationship to involution in the male reproductive system with aging. We fed a VED or control diet to 4-week-old mice for 12 or 24 weeks. Following the histopathological analysis of reproductive organs, we found seminiferous tubules with exfoliation in the VED groups, and its frequency was significantly increased compared with the controls. Additionally, in the epididymis, a decrease in spermatozoa and an increase in apoptotic germ cells were observed in the VED groups compared with the controls. By Papanicolaou staining, we also found an increase in the proportion of sperm with abnormal morphology in the VED groups compared with the controls. These reproductive effects induced by VED were highly similar to one aspect of those observed in aged mice. Our findings demonstrate that the aging of the male reproductive system may be accelerated because of the impaired in vivo antioxidant capacity induced by VED.

Sina Vakili, Fatemeh Zal, Zohreh Mostafavi-Pour, Amir Savardashtaki, Farhad Koohpeyma

J Cell Physiol . 2020 Oct 8. doi: 10.1002/jcp.30087. Online ahead of print.

Abstract

Osteoporosis is the most prevalent metabolic bone disease and one of the most important postmenopausal consequences. The aim of this study was to investigate the effects of quercetin (Q) and vitamin E (vitE) on ovariectomy-induced osteoporosis. Animals were ovariectomized and treated with Q (15 mg/kg/day), vitE (60 mg/kg/day), estradiol (10 µg/kg/day), and Q (7.5 mg/kg/day) + vitE (30 mg/kg/day) for 10 weeks by gavage, and osteoporosis markers and messenger RNA (mRNA) expression of autophagy and apoptosis-related genes were analyzed in serum and tibia of rats. Data indicated that ovariectomy resulted in development of osteoporosis as demonstrated by reduction in serum calcium, bone weight, bone volume, trabeculae volume, and the total number of osteocytes and osteoblasts, and increase in the total number of osteoclasts and serum osteocalcin. Total mRNA expressions of LC3, beclin1, and caspase 3 were also increased and bcl2 expression was decreased in the tibia. By reversing these changes, treatment with Q and vitE markedly improved osteoporosis. In conclusion, Q, and to a lesser extent, vitE, prevented osteoporosis by regulating the total number of bone cells, maybe through regulating autophagy and apoptosis.

Pardis Irandoost, Naimeh Mesri Alamdari, Atoosa Saidpour, Farzad Shidfar, Neda Roshanravan, Mohammad Asghari Jafarabadi, Farnaz Farsi, Nazanin Asghari Hanjani, Mohammadreza Vafa

J Food Biochem . 2020 Oct 5;e13493. doi: 10.1111/jfbc.13493. Online ahead of print.

Abstract

The effects of royal jelly (RJ) and tocotrienol-rich fraction (TRF) on obesity-induced glucose intolerance and inflammation were assessed in the current study. Regarding irisin as an important adipomyokine that attenuates obesity-induced disorders, we evaluated whether RJ and TRF could exert their metabolism regulatory effects through irisin. Obese rats were fed a high-fat diet (HFD) with or without supplementation of RJ, TRF, or both, for 8 weeks. At the end of the intervention, weight, irisin, glycemic, and inflammatory indices were measured. The weight of the rats did not remarkably reduce in any of the groups. Glucose homeostasis and inflammation were improved when we added RJ and TRF to HFD. RJ elevated irisin concentration, but the effect of TRF on irisin was not noticeable. Our results indicated that, despite the lack of significant weight loss, RJ and TRF promoted healthy obesity. This improvement was mediated by irisin in RJ consuming rats. PRACTICAL APPLICATIONS: Obesity is a public health concern associated with several chronic disorders. The beneficial effects of irisin on obesity-related disorders are well-established. It is the first study assessing the effect of RJ and TRF as functional foods, with pharmacological and nutritional activities on obesity complications, through irisin mediation. Our study demonstrated that RJ exerts its metabolic regulatory effects by irisin as a mediator. Our investigation makes a remarkable contribution to the literature, because it suggests a new mechanism for the anti-obesity properties of RJ and TRF.

Abdulmonim A Alqasim, Essam Eldin M Nour Eldin, Sami H Hammadi, Ghada E Esheba

J Taibah Univ Med Sci . 2020 Jul 17;15(5):351-357. doi: 10.1016/j.jtumed.2020.05.007. eCollection 2020 Oct.

Abstract

Objectives: Diabetes mellitus is associated with oxidative stress that leads to inflammation and diabetic nephropathy. This study aimed to determine the possible renoprotective effects of the antioxidants melatonin, vitamin D and vitamin E in diabetic rats.

Methods: We divided 108 albino rats into 12 groups. G1 group was fed a normal diet and did not receive any medication. G2 to G4 consisted of non-diabetic rats that were treated as follows: G2 with melatonin; G3 with vitamin E; G4 with vitamin D. Groups G5 to G12 consisted of diabetic rats that were treated as follows: G5 received no medication; G6 treated with insulin; G7 treated with melatonin; G8 treated with melatonin and insulin; G9 treated with vitamin E; G10 treated with vitamin E and insulin; G11 treated with vitamin D and G12 treated with vitamin D and insulin. Two months after treatment commenced, histological and biochemical examinations of glucose profile, oxidative stress status, renal function, homocysteine and TNF-α were performed.

Results: Total antioxidant capacity (TAC) increased significantly in groups G2, 7, 8, 10 and 11. TNF-α significantly increased in G2, but decreased in all other groups. Creatinine increased significantly in groups G5, 6, 7, 8, 9, 11 and 12. In the kidneys of the diabetic rats, thickened capillary basement membrane, diffuse mesangial sclerosis and nodular glomerulosclerosis was observed. Rats treated with melatonin showed marked improvement in these symptoms. However, in those treated with vitamin D and E, thickened capillary basement membrane and mesangial sclerosis was still present.

Conclusions: Melatonin, administered either with or without insulin had a significant biochemical antioxidant effect and histological renoprotective effect. Conversely, vitamin D and E did not appear to have any effects on the parameters measured.

Kilmer S McCully

Ann Clin Lab Sci . 2020 Sep;50(5):567-577.

Abstract

A century ago a fat-soluble vitamin from leafy vegetables, later named vitamin E, was discovered to enhance fertility in animals. Vitamin E consists of 8 isomers of tocopherols and tocotrienols, each containing chromanol groups that confer antioxidant properties and differ only in the 15-carbon saturated phytyl poly-isoprenoid side chain of tocopherols and the 15-carbon unsaturated farnesyl poly-isoprenoid side chain of tocotrienols. Although tocotrienol was first isolated from rubber plants in 1964, its importance in multiple disease processes was not recognized until two decades later, when the cholesterol-lowering and anti-cancer effects were first reported. Tocotrienol (T3) protects against radiation injury and mitochondrial dysfunction by preventing opening of the mitochondrial permeability transition pore, thereby inhibiting loss of the active site for oxidative phosphorylation, thioretinaco ozonide oxygen ATP, from mitochondria by complex formation with the active site, TR₂CoO₃O₂NAD⁺H₂PO₄ ^–T3. The preventive effects of tocotrienol on vascular disease, cancer, neurodegeneration and aging are attributed to its effects on cellular apoptosis and senescence. Geranylgeraniol is an important intermediate in the biosynthesis of cholesterol, and cholesterol auxotrophy of lymphoma cell lines and primary tumors is attributed to loss of squalene monooxygenase and accumulation of intracellular squalene. Geranylgeraniol and tocotrienol have synergistic inhibitory effects on growth and HMG CoA reductase activity, accompanied by reduction of membrane KRAS protein of cultured human prostate carcinoma cells. Since cholesterol inhibits opening of the mPTP pore of mitochondria, inhibition of cholesterol biosynthesis by these effects of tocotrienol and geranylgeraniol produces increased mitochondrial dysfunction and apoptosis from loss of the active site of oxidative phosphorylation from mitochondria.

Melanie Ziegler, Maria Wallert, Stefan Lorkowski, Karlheinz Peter

Antioxidants (Basel) . 2020 Sep 29;9(10):935. doi: 10.3390/antiox9100935.

Abstract

Cardiovascular diseases (CVD) cause about 1/3 of global deaths. Therefore, new strategies for the prevention and treatment of cardiovascular events are highly sought-after. Vitamin E is known for significant antioxidative and anti-inflammatory properties, and has been studied in the prevention of CVD, supported by findings that vitamin E deficiency is associated with increased risk of cardiovascular events. However, randomized controlled trials in humans reveal conflicting and ultimately disappointing results regarding the reduction of cardiovascular events with vitamin E supplementation. As we discuss in detail, this outcome is strongly affected by study design, cohort selection, co-morbidities, genetic variations, age, and gender. For effective chronic primary and secondary prevention by vitamin E, oxidative and inflammatory status might not have been sufficiently antagonized. In contrast, acute administration of vitamin E may be more translatable into positive clinical outcomes. In patients with myocardial infarction (MI), which is associated with severe oxidative and inflammatory reactions, decreased plasma levels of vitamin E have been found. The offsetting of this acute vitamin E deficiency via short-term treatment in MI has shown promising results, and, thus, acute medication, rather than chronic supplementation, with vitamin E might revitalize vitamin E therapy and even provide positive clinical outcomes.

Nurgül Bas, Nezahat Arzu Kayar, Z Füsun Baba, Mustafa Cihat Avunduk, Seyfullah Haliloğlu, Nilgün Özlem Alptekin

Clin Oral Investig . 2020 Sep 28. doi: 10.1007/s00784-020-03579-9. Online ahead of print.

Abstract

Objective: To investigate the effects of sodium selenite (Se) and/or α-tocopherol (αT) applications on the alveolar bone loss (ABL), the number of gingival collagen fibers, inducible nitric oxide synthase (iNOS)+ and CD95+ cell numbers, and serum cytokine concentrations in experimental periodontitis in rats.

Materials and methods: Forty Sprague Dawley rats were divided into four groups of ten as follows: group A: Se group, group B: αT group, group C: Se and αT combined group, and group D: control group (intraperitoneal (IP) saline injection applied). Using the image analysis method in the connective tissue under the connective epithelium, the numbers of iNOS, CD95 positive cells, and collagen fibers were counted. ELISA kits were used to test the concentrations of serum interleukin (IL)-1β, IL-6, and IL-4.

Results: The combination of Se and αT (group C) suppressed ABL compared with the control group (group D) (P < 0.05). In group A (Se), the number of iNOS+ cells was smaller than in group D (P < 0.05).

Conclusion: Se has been concluded to inhibit inflammation of the gum due to iNOS. Se and αT can have a remarkable important role in preventing alveolar bone loss, and particularly in combination.

Clinical relevance: Se and/or αT application may be useful in preventing the destruction of periodontal tissue and treatment of periodontal disease.

Esra Bolat, Elçin Esenlik, Meral Öncü, Meltem Özgöçmen, Mustafa Cihat Avunduk, Özlem Yüksel

J Dent Res Dent Clin Dent Prospects . Spring 2020;14(2):131-137. doi: 10.34172/joddd.2020.0027. Epub 2020 Jun 17.

Abstract

Background. This experimental study aimed to assess the effects of Vitamins C and E on orthodontic tooth movement. Methods. Fifty-one male Wistar albino rats were divided into six groups: five appliance groups and one control group. The appliance groups had an orthodontic appliance consisting of a closed-coil spring ligated between the maxillary incisor and maxillary first molar (50 g). Vitamin E and C (150 mg/kg) were injected intraperitoneally per day in the first and second groups, respectively. Vitamins E and C (20 μL) were locally injected into the periodontal gap of the moving teeth in the third and fourth groups, respectively, once every three days. No vitamin was injected in the last (fifth) appliance group.The experimental period was 18 days. Histological and biochemical (alkaline phosphatase, osteocalcin, and NTx levels) evaluations of the samples were performed, and maxillary incisor‒molar distance was measured before and after the experiment. Results. The amount of tooth movement was similar in the appliance groups. All the vitamin groups showed significantly increased osteoblastic activity, while those treated with systemic vitamins exhibited significantly increased numbers of collagen fibers on the tension side compared to the appliance control group (P<0.05). Conclusion. Vitamin C and E supplements positively affected bone formation on the tension side of the teeth during experimental orthodontic tooth movement.

Hongwei Shen, Bingyan Zhan

J Int Med Res . 2020 Sep;48(9):300060520949657. doi: 10.1177/0300060520949657.

Abstract

Objective: To study the role of vitamin E in stroke-associated pneumonia.

Methods: We selected 183 patients with stroke-related pneumonia who were divided into different nutrition groups according to the Mini Nutritional Assessment score. Patients were then administered different doses of vitamin E.

Results: CD55 and CD47 levels in patients taking vitamin E across different nutrition score groups were better than those in patients who did not use vitamin E. The levels of CD55 and CD47 and the duration of hospitalization were better in the high-dose vitamin E group than in the low-dose vitamin E group.

Conclusion: Vitamin E may have an auxiliary therapeutic effect in patients with stroke-associated pneumonia.