RESUMEN
A well-known natural ingredient found in several medicinal plants, berberine (Ber), has been shown to have anticancer properties against a range of malignancies. The limited solubility and bioavailability of berberine can be addressed using Ber-loaded nanoparticles. In this study, we compared the in vitro cytotoxic effects of both Ber-loaded silver nanoparticles (Ber-AgNPs) and Ber-loaded selenium nanoparticles (Ber-SeNPs) in the human liver cancer cell line (HepG2) and mouse normal liver cells (BNL). The IC50 values in HepG2 for berberine, Ber-AgNPs, Ber-SeNPs, and cisplatin were 26.69, 1.16, 0.04, and 0.33 µg/mL, respectively. Our results show that Ber and its Ag and Se nanoparticles exerted a good antitumor effect against HepG2 cells by inducing apoptosis via upregulating p53, Bax, cytosolic cytochrome C levels, and caspase-3 activity, and the down-regulation of Bcl-2 levels. Similarly, incubation with Ber and both Ber-NPs (Ag and Se) led to a significant dose-dependent elevation in inflammatory markers' (TNF-α, NF-κB, and COX-2) levels compared to the control group. In addition, it led to the arrest of the G1 cell cycle by depleting the expression of cyclin D1 and CDK-2 mRNA. Furthermore, Ber and both Ber-NPs (Ag and Se) caused a significant dose-dependent increase in LDH activity in HepG2 cells. Furthermore, our findings offer evidence that Ber and its nanoparticles intensified oxidative stress in HepG2 cells. Furthermore, the migration rate of cells subjected to berberine and its nanoforms was notably decreased compared to that of control cells. It can be inferred that Ber nanoparticles exhibited superior anticancer efficacy against HepG2 compared to unprocessed Ber, perhaps due to their improved solubility and bioavailability. Furthermore, Ber-SeNPs exhibited greater efficacy than Ber-AgNPs, possibly as a result of the inherent anticancer characteristics of selenium.
Asunto(s)
Berberina , Carcinoma Hepatocelular , Neoplasias Hepáticas , Nanopartículas del Metal , Selenio , Ratones , Animales , Humanos , Carcinoma Hepatocelular/tratamiento farmacológico , Carcinoma Hepatocelular/patología , Selenio/farmacología , Berberina/farmacología , Plata/farmacología , Neoplasias Hepáticas/patología , Línea CelularRESUMEN
Schizophrenia (SCZ), a multifactorial neuropsychiatric disorder, is treated with inefficient antipsychotics and linked to poor treatment outcomes. This study, therefore, investigated the combined administration of prodigiosin (PDG) and selenium (Na2SeO3) against SCZ induced by amphetamine (AMPH) in rats. Animals were allocated into four groups corresponding to their respective 7-day treatments: control, AMPH (2 mg/kg), PDG (300 mg/kg) + Na2SeO3 (2 mg/kg), and AMPH + PDG + Na2SeO3. The model group exhibited biochemical, molecular, and histopathological changes similar to those of the SCZ group. Contrastingly, co-administration of PDG and Na2SeO3 significantly increased the time for social interaction and decreased AChE and dopamine. It also downregulated the gene expression of NMDAR1 and restored neurotrophin (BDNF and NGF) levels. Further, PDG combined with Na2SeO3 improved the antioxidant defence of the hippocampus by boosting the activities of SOD, CAT, GPx, and GR. These findings were accompanied by an increased GSH, alongside decreased MDA and NO levels. Furthermore, schizophrenic rats having received PDG and Na2SeO3 displayed markedly lower IL-1ß and TNF-α levels compared to the model group. Interestingly, remarkable declines in the Bax (pro-apoptotic) and increases in Bcl-2 (anti-apoptotic) levels were observed in the SCZ group that received PDG and Na2SeO3. The hippocampal histological examination confirmed these changes. Collectively, these findings show that the co-administration of PDG and Na2SeO3 may have a promising therapeutic effect for SCZ. This is mediated by mechanisms related to the modulation of cholinergic, dopaminergic, and glutaric neurotransmission and neurotrophic factors, alongside the suppression of oxidative damage, neuroinflammation, and apoptosis machinery.
Asunto(s)
Selenio , Ratas , Animales , Selenio/farmacología , Prodigiosina , Antioxidantes/farmacología , Estrés Oxidativo , Anfetamina/farmacología , Suplementos DietéticosRESUMEN
The present study evaluated the effects of Hail Salvia officinalis total extract (SOTE) and its high flavonoid fraction (SOHFF) on the high-fat diet (HFD)-induced obesity and hepatorenal damage in rats. Salvia officinalis plants were collected from Hail region, Saudi Arabia. Rats were fed HFD and supplemented orally with SOTE (250 mg kg-1) or SOHFF (100 mg kg-1) or simvastatin (SVS; 10 mg kg-1) every day for 8 weeks. Compared to the controls, HFD-induced obesity led to significant increases in body weight, body weight gained, blood insulin, leptin, cardiac enzymes (LDH and CPK) activity, and atherogenic index (AI). HFD rats also showed higher levels of hepatic and renal function biomarkers (ALT, urea, and creatinine), as well as lower levels of PPARγ and Nrf2-gene expression and a disrupted lipid profile. Moreover, HFD rats had lower levels of hepatic and renal antioxidant biomarkers (CAT, GPx, SOD, GR, and GSH), accompanied by higher levels of hepatic and renal lipid peroxidation (LPO), nitric oxide (NO), and inflammatory mediators (interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α)). In addition, histological examination of hepatic and renal tissues revealed histopathological changes that validated the biochemical findings. Compared to HFD group, SOTE and SOHFF treatment led to marked amelioration of all the aforementioned parameters. Collectively, supplementation with SOTE and SOHFF effectively reversed HFD-induced alterations through its antioxidant, hypolipidemic, and anti-inflammatory properties. Hence, SOTE and SOHFF have therapeutic potential in controlling obesity and related pathologies.
Asunto(s)
Insulinas , Salvia officinalis , Animales , Antioxidantes/metabolismo , Biomarcadores/metabolismo , Peso Corporal , Creatinina , Dieta Alta en Grasa/efectos adversos , Flavonoides/farmacología , Mediadores de Inflamación/metabolismo , Mediadores de Inflamación/farmacología , Mediadores de Inflamación/uso terapéutico , Insulinas/metabolismo , Insulinas/farmacología , Insulinas/uso terapéutico , Interleucina-1beta/metabolismo , Leptina , Lípidos , Factor 2 Relacionado con NF-E2/metabolismo , Óxido Nítrico/farmacología , Obesidad , Estrés Oxidativo , PPAR gamma/metabolismo , PPAR gamma/farmacología , PPAR gamma/uso terapéutico , Extractos Vegetales/farmacología , Extractos Vegetales/uso terapéutico , Ratas , Simvastatina , Superóxido Dismutasa/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Urea/farmacologíaRESUMEN
The perennial plant Echinops spinosus (ES) grows in the Hail area of Saudi Arabia, and its traditional formulations are often employed in folk medicine. The goal of this study is to identify the active components present in Hail Echinops spinosus and to investigate the anti-diabetic properties of both ES total extract (ESTE) and its high flavonoids fraction (ESHFF) in experimental diabetes induced by streptozotocin (STZ) injection in rats. Forty-two rats were divided into six groups. Diabetes was induced using STZ (55 mg/kg). Seven days after STZ administration, the diabetic animals were treated daily with ESTE, ESHFF, or metformin (MET) as a standard anti-diabetic drug for 28 days. Blood and tissues samples were collected for biochemical, molecular, and histological investigations. Both ESTE and ESHFF demonstrated anti-diabetic properties, as evidenced by lowering glucose levels and increasing the levels of insulin, insulin receptor expression rate, and glycogen synthesis. Additionally, ESTE as well as ESHFF alleviated diabetic complications in the kidneys and liver by decreasing oxidative stress, modulating inflammatory mediators, and suppressing the apoptotic cascade along with correcting diabetic dyslipidemia. It could be deduced that Hail ES extracts could play a role in the treatment of type 2 diabetes and diabetes-related lesions as well as oxidative damage in hepatic and renal tissues.
Asunto(s)
Diabetes Mellitus Tipo 2 , Flavonoides , Animales , Glucemia/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Flavonoides/metabolismo , Flavonoides/farmacología , Hipoglucemiantes/farmacología , Hipoglucemiantes/uso terapéutico , Hígado , Estrés Oxidativo , Extractos Vegetales/química , Ratas , Estreptozocina/metabolismo , Estreptozocina/farmacología , Estreptozocina/uso terapéutico , TenrecidaeRESUMEN
BACKGROUND: Drawbacks and side effects of currently available therapies to colorectal cancer (CRC) have compelled researchers to search for new therapeutic strategies. OBJECTIVE: This study was designed to investigate the effects of zinc nanoparticles biosynthesized with berberine (ZnNPs-BER) on Caco-2 cells compared to 5-Fluorouracil (5-FU) and explore the possible underlying pathways. METHODS: Caco-2 and Vero cells were treated with 5-FU, BER, or ZnNPs-BER for 24 h. Cell viability was measured by MTT assay. Oxidative stress and apoptotic markers and cell cycle were determined. Additionally, Cox-2 and NF-kB levels were also measured. RESULTS: The IC50 values of 5-FU, BER, and ZnNPs-BER on Caco-2 cells were found to be 34.65 µM, 19.86 µg/ml and 10.49 µg/ml, respectively by MTT assay. The IC50 value for 5-FU in Vero cells was 21.7 µg/ml, however, BER and BER-ZnNPs treatment showed non-toxic effects on the Vero cells. Further, ZnNPs-BER exerted significant induction of ROS besides exhaustion of the antioxidant capacity of tumor cells indicated by a decline in GSH and elevated NO and MDA contents. Marked increments in levels of Bax and caspase-3 were detected together with declines in Bcl- 2 levels in Caco-2 cells subjected to BER-ZnNPs therapy. On the molecular basis, upregulation in mRNA levels of pro-apoptotic genes (Bax, caspase-3, and tumor suppressor gene p53) along with downregulation in the anti-apoptotic gene (Bcl-2) were observed in ZnNPs-BER treated Caco-2 cells. Furthermore, ZnNPs-BER showed more pronounced effects on apoptosis increased cell percentage in the S and subG1 phases. In addition, green synthesis of ZnNPs with BER showed notable induction of Cox2 and NF-kB in Caco-2 cells. CONCLUSION: Therefore, the antitumor potential of ZnNPs-BER in colon cancer cells may be endorsed for induction of oxidative stress, inflammation, and apoptotic changes in tumor cells. Our study documents the therapeutic potential of Zn nanoparticles conjugated with BER, which may be a new option for combined chemotherapy.
Asunto(s)
Adenocarcinoma , Berberina , Neoplasias Colorrectales , Nanopartículas del Metal , Animales , Apoptosis , Berberina/farmacología , Células CACO-2 , Caspasa 3/metabolismo , Chlorocebus aethiops , Fluorouracilo/farmacología , Humanos , FN-kappa B/metabolismo , Proteína p53 Supresora de Tumor/genética , Células Vero , Zinc/farmacología , Proteína X Asociada a bcl-2/metabolismoRESUMEN
BACKGROUND: Mercuric chloride (HgCl2) severely impairs the central nervous system when humans are exposed to it. AIMS: We investigated the neuroprotective efficiency of Ziziphus spina-christi leaf extract (ZSCLE) on HgCl2-mediated cortical deficits. METHODS: Twenty-eight rats were distributed equally into four groups: the control, ZSCLE-treated (300 mg/kg), HgCl2-treated (0.4 mg/kg), and ZSCLE+HgCl2-treated groups. Animals received their treatments for 28 days. RESULTS: Supplementation with ZSCLE after HgCl2 exposure prevented the deposition of mercury in the cortical slices. It also lowered malondialdehyde levels and nitrite and nitrate formation, elevated glutathione levels, activated its associated-antioxidant enzymes, glutathione reductase, and glutathione peroxidase, and upregulated the transcription of catalase and superoxide dismutase and their activities were accordingly increased. Moreover, ZSCLE activated the expression of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 when compared with the HgCl2 group. Notably, post-treatment with ZSCLE increased the activity of acetylcholinesterase and ameliorated the histopathological changes associated with HgCl2 exposure. Furthermore, ZSCLE blocked cortical inflammation, as observed by the lowered mRNA expression and protein levels of interleukin-1 beta and tumor necrosis factor-alpha, as well as decreased mRNA expression of inducible nitric oxide synthase. In addition, ZSCLE decreased neuron loss by preventing apoptosis in the cortical tissue upon HgCl2 intoxication. CONCLUSION: Based on the obtained findings, we suggest that ZSCLE supplementation could be applied as a neuroprotective agent to decrease neuron damage following HgCl2 toxicity.
Asunto(s)
Cloruro de Mercurio , Ziziphus , Acetilcolinesterasa/metabolismo , Animales , Antioxidantes/farmacología , Cloruro de Mercurio/metabolismo , Cloruro de Mercurio/toxicidad , Estrés Oxidativo , Extractos Vegetales/farmacología , Ratas , Ziziphus/metabolismoRESUMEN
Here, we examined the protective effect of ferulic acid (FA) on cadmium chloride (CdCl2 )-mediated reproductive toxicity in male rats. Animals were divided into four groups: control, FA (20 mg/kg), CdCl2 (6.5 mg/kg), and FA + CdCl2 . CdCl2 treatment evoked a significant increase in testis cadmium concentration in addition to obvious increase in testosterone, luteinizing hormone, and follicle-stimulating hormone levels. Moreover, CdCl2 -induced oxidative damage through exhausting the cellular defenses (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione) and downregulating the nuclear factor erythroid 2-related factor 2 (Nrf2) expression accompanied by increases of malondialdehyde and nitric oxide contents. Testicular inflammation was evident indicated by increased levels of interleukin-1ß and tumor necrosis factor-α in CdCl2 -treated rats. CdCl2 exposure also decreased the expression of the proliferating cell nuclear antigen and augmented apoptotic events associated with prominent histopathological alterations. However, FA coadministration mitigated the impaired hormonal level, apoptotic and inflammatory injuries elicited by CdCl2, and maintained the oxidant/antioxidant balance in testicular tissue via Nrf2 activation. PRACTICAL APPLICATIONS: Cadmium is an environmental toxicant and known to cause adverse effects including reproductive toxicity. However, antioxidant application has been found to protect against heavy metals-mediated toxic effects. Here, we examined the potential protective efficacy of ferulic acid against cadmium-mediated testicular impairments through estimating the amount of cadmium in the testis, hormonal profile, oxidative status, inflammatory response, apoptotic and proliferating markers in addition to the histopathological alterations. The obtained findings revealed that ferulic acid supplementation was able to abolish the testicular damages coupled with cadmium exposure. The protective efficiency of ferulic acid may correlated with its strong antioxidant, anti-inflammatory, and antiapoptotic activities; suggesting that ferulic acid may be used to ameliorate cadmium-induced testicular deficits.
Asunto(s)
Cadmio , Factor 2 Relacionado con NF-E2 , Animales , Apoptosis , Cadmio/toxicidad , Ácidos Cumáricos , Inflamación , Masculino , Factor 2 Relacionado con NF-E2/metabolismo , Estrés Oxidativo , RatasRESUMEN
BACKGROUND: Prostate Cancer (PCa) is defined as a major health problem faced by the male population. AIM: We aimed to investigate the protective effects of Orange Peel Extract (OPE) and/or Selenium (Se) on chronic non-bacterial prostatitis in a rat model. METHODS: Fifty-six adult male Wistar albino rats were castrated; after 5 days, they were divided randomly into eight groups (n= 7). The control group received saline treatment; while 17ß-estradiol (E2) (0.25mg/kg) was injected subcutaneously in rats from Groups V, VI, VII, and VIII to induce chronic non-bacterial prostatitis. They were then treated with OPE (400mg/kg body weight; Groups II, IV, VI, and VIII) and/or sodium selenite (0.5mg/kg body weight; Groups III, IV, VII, and VIII) for 30 days. Interleukin-2 (IL2) and Prostate Cancer Antigen 3 (PCA3) mRNA expressions were determined using qPCR; Prostate-Specific Antigen (PSA) protein expression was determined immunohistochemically. Prostate tissue histology was examined by hematoxylin and eosin staining, and the levels of oxidative stress markers and antioxidant enzymes were measured. RESULTS: E2 administration significantly increased IL2 and PCA3 mRNA expressions, and PSA protein expression. It also increased the prostate wet weight and body weight, and lipid peroxidation, nitric oxide, TNF-α, and IL-1ß levels, decreased the glutathione and antioxidant enzyme levels and caused distinct histological alterations in the prostate gland. OPE and/or Se markedly improved all the studied parameters due to their antioxidant properties and anti-inflammatory effects. CONCLUSION: OPE and Se showed protective effects against 17ß-estradiol-induced chronic non-bacterial prostatitis. These results suggest that protection of chronic non-bacterial prostatitis by OPE+Se combination involves anti-oxidation and anti-inflammation. Moreover, their synergistic mechanism was mostly achieved via the regulation of oxidative stress and inflammation processes.
Asunto(s)
Citrus sinensis/química , Extractos Vegetales/farmacología , Prostatitis/prevención & control , Sustancias Protectoras/farmacología , Selenio/farmacología , Animales , Enfermedad Crónica , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Estradiol/administración & dosificación , Inyecciones Subcutáneas , Masculino , Estructura Molecular , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Prostatitis/inducido químicamente , Sustancias Protectoras/química , Sustancias Protectoras/aislamiento & purificación , Ratas , Ratas Wistar , Selenio/química , Relación Estructura-ActividadRESUMEN
Sepsis is a systemic response to infection that can result in acute hepatic and splenic damage. Ziziphus spina-christi (L.) is a wild tree used as a medicinal plant by ancient Egyptians. However, little is known about the mechanism underlying its effects on sepsis. The current study investigated the protective effects of a Z. spina-christi leaf extract (ZSCLE) on liver and spleen damage in a male C57BL/6 mouse model of sepsis, induced by cecal ligation and puncture (CLP). Prior to CLP, ZSCLE was administered daily for five consecutive days via oral gavage at doses of 100, 200, or 300 mg/kg. The mice were euthanized 9 h after CLP, and oxidative stress markers were measured (myeloperoxidase, lipid peroxidation, nitric oxide, and reduced glutathione). In addition, we investigated histological changes, anti-oxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase), cytokine levels, protein expression of nuclear factor-κB and inducible nitric oxide synthase (iNOS), and mRNA levels of mitogen-activated protein kinase (8, 9, and 14), iNOS, tumor necrosis factor-α, and interleukin-1ß. Our results indicated that ZSCLE significantly and dose-dependently inhibited sepsis-induced liver and spleen injury. These results suggest that ZSCLE could provide a therapeutic agent for sepsis by inducing anti-inflammatory and anti-oxidant effects.
Asunto(s)
Antiinflamatorios/uso terapéutico , Antioxidantes/uso terapéutico , Hígado/efectos de los fármacos , Sepsis/tratamiento farmacológico , Bazo/efectos de los fármacos , Ziziphus , Animales , Antiinflamatorios/aislamiento & purificación , Antiinflamatorios/farmacología , Antioxidantes/aislamiento & purificación , Antioxidantes/farmacología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Hígado/lesiones , Hígado/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/farmacología , Extractos Vegetales/uso terapéutico , Hojas de la Planta , Sepsis/metabolismo , Bazo/lesiones , Bazo/metabolismoRESUMEN
Radiotherapy-induced gut toxicity is among the most prevalent dose-limiting toxicities following radiotherapy. Prevention of radiation enteropathy requires protection of the small intestine. However, despite the prevalence and burden of this pathology, there are currently no effective treatments for radiotherapy-induced gut toxicity, and this pathology remains unclear. The present study aimed to investigate the changes induced in the rat small intestine after external irradiation of the tongue, and to explore the potential radio-protective effects of melatonin gel. Male Wistar rats were subjected to irradiation of their tongues with an X-Ray YXLON Y.Tu 320-D03 irradiator, receiving a dose of 7.5 Gy/day for 5 days. For 21 days post-irradiation, rats were treated with 45 mg/day melatonin gel or vehicle, by local application into their mouths. Our results showed that mitochondrial oxidative stress, bioenergetic impairment, and subsequent NLRP3 inflammasome activation were involved in the development of radiotherapy-induced gut toxicity. Oral treatment with melatonin gel had a protective effect in the small intestine, which was associated with mitochondrial protection and, consequently, with a reduced inflammatory response, blunting the NF-κB/NLRP3 inflammasome signaling activation. Thus, rats treated with melatonin gel showed reduced intestinal apoptosis, relieving mucosal dysfunction and facilitating intestinal mucosa recovery. Our findings suggest that oral treatment with melatonin gel may be a potential preventive therapy for radiotherapy-induced gut toxicity in cancer patients.
Asunto(s)
Mucosa Intestinal/patología , Intestino Delgado/patología , Melatonina/administración & dosificación , Traumatismos Experimentales por Radiación/prevención & control , Protectores contra Radiación/administración & dosificación , Animales , Apoptosis , Evaluación Preclínica de Medicamentos , Geles , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/efectos de la radiación , Intestino Delgado/efectos de los fármacos , Intestino Delgado/metabolismo , Intestino Delgado/efectos de la radiación , Masculino , FN-kappa B/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Fosforilación Oxidativa , Estrés Oxidativo , Traumatismos Experimentales por Radiación/metabolismo , Traumatismos Experimentales por Radiación/patología , Ratas Wistar , Lengua/efectos de la radiaciónRESUMEN
Lead (Pb) enhances the production of reactive oxygen species and depletes the antioxidant molecules that cause tissue damage. In the current study, we investigated the protective effect of Indigofera oblongifolia (hasr in Arabic) against lead acetate-induced reproductive toxicity in rats. Exposure of rats to lead acetate (PbAc; 20 mg/kg body weight; intraperitoneal injection) induced a significant change in both of body weight loss and the relative testis weight. Furthermore, a significant increase in lipid peroxidation and nitric oxide and a marked depletion of glutathione were evident in the testis of the PbAc group compared to the control group. Also, PbAc significantly reduced the activity of antioxidant enzymes. Pre-administration of I. oblongifolia leaves extract (IOLE; 100 mg/kg body weight) to the PbAc-treated rats restored most of the parameters mentioned above to near-normal levels. Additionally, pretreatment of animals with IOLE accompanied with a significant decrease in the toxic effects of PbAc as shown by caspase-3 and Bax expressions and prevented the histological injury in the testis. On the basis of the above results, I. oblongifolia appeared to be a promising agent for protection against lead-induced oxidative damage and apoptosis in the testis of rat.
Asunto(s)
Apoptosis/efectos de los fármacos , Indigofera/química , Compuestos Organometálicos/toxicidad , Estrés Oxidativo/efectos de los fármacos , Extractos Vegetales/farmacología , Hojas de la Planta/química , Testículo/metabolismo , Animales , Caspasa 3/biosíntesis , Regulación de la Expresión Génica/efectos de los fármacos , Masculino , Extractos Vegetales/química , Ratas , Ratas Wistar , Testículo/patología , Proteína X Asociada a bcl-2/biosíntesisRESUMEN
Alzheimer's disease (AD) is the most common form of dementia characterized by progressive loss of memory and other cognitive functions among older people. Senile plaques and neurofibrillary tangles are the most hallmarks lesions in the brain of AD in addition to neurons loss. Accumulating evidence has shown that oxidative stress-induced damage may play an important role in the initiation and progression of AD pathogenesis. Redox impairment occurs when there is an imbalance between the production and quenching of free radicals from oxygen species. These reactive oxygen species augment the formation and aggregation of amyloid-ß and tau protein hyperphosphorylation and vice versa. Currently, there is no available treatments can modify the disease. However, wide varieties of antioxidants show promise to delay or prevent the symptoms of AD and may help in treating the disease. In this review, the role of oxidative stress in AD pathogenesis and the common used antioxidant therapies for AD will summarize.