A Ginkgo biloba extract (EGb 761) prevents mitochondrial aging by protecting against oxidative stress

Spermidine Enhances Mitochondrial Bioenergetics in Young and Aged Human-Induced Pluripotent Stem Cell-Derived Neurons

The accumulation of damaged mitochondria has long been considered a hallmark of the aging process. Among various factors, age-related mitochondrial alterations comprise bioenergetic impairments and disturbances in reactive oxygen species (ROS) control, thereby negatively affecting mitochondrial performance and ultimately accelerating aging. Previous studies have revealed that polyamine spermidine appears to exert health-protective and lifespan-promoting effects. Notably, recent findings have also described a spermidine-induced improvement in age-associated mitochondrial dysfunction, but the beneficial effects of spermidine on aged mitochondria have not been entirely examined yet. Here, we show that spermidine positively regulates several parameters related to mitochondrial bioenergetics and mitochondrial redox homeostasis in young and aged human-induced pluripotent stem cell-derived neurons. We report that spermidine treatment increases adenosine triphosphate production and mitochondrial membrane potential, which is accompanied by an attenuation in mitochondrial ROS levels in both age groups. Furthermore, we demonstrate a spermidine-mediated amelioration in mitochondrial respiration in both young and aged neurons. Overall, our findings suggest that nutritional spermidine supplementation might represent an attractive therapeutic approach to enhance mitochondrial function, consequently decelerating aging.

Delineating the contribution of ageing and physical activity to changes in mitochondrial characteristics across the lifespan

Ageing is associated with widespread physiological changes prominent within all tissues, including skeletal muscle and the brain, which lead to a decline in physical function. To tackle the growing health and economic burdens associated with an ageing population, the concept of healthy ageing has become a major research priority. Changes in skeletal muscle mitochondrial characteristics have been suggested to make an important contribution to the reductions in skeletal muscle function with age, and age-related changes in mitochondrial content, respiratory function, morphology, and mitochondrial DNA have previously been reported. However, not all studies report changes in mitochondrial characteristics with ageing, and there is increasing evidence to suggest that physical activity (or inactivity) throughout life is a confounding factor when interpreting age-associated changes. Given that physical activity is a potent stimulus for inducing beneficial adaptations to mitochondrial characteristics, delineating the influence of physical activity on the changes in skeletal muscle that occur with age is complicated. This review aims to summarise our current understanding and knowledge gaps regarding age-related changes to mitochondrial characteristics within skeletal muscle, as well as to provide some novel insights into brain mitochondria, and to propose avenues of future research and targeted interventions. Furthermore, where possible, we incorporate discussions of the modifying effects of physical activity, exercise, and training status, to purported age-related changes in mitochondrial characteristics.

Bacterial Reverse Mutation Test of Verbenalin

Objectives

Verbenalin is a compound found in herbs such as Cornus officinalis and Verbena officinalis. This study investigated whether verbenalin is safe by analyzing its mutagenicity.

Methods

To examine the mutagenic potential of verbenalin, a bacterial reverse mutation test (Ames test) was conducted with Salmonella typhimurium and Escherichia coli strains. Experiments with and without metabolic activity were performed.

Results

The mean colony number was less than double that of the control. Growth inhibition and precipitation of verbenalin were not apparent in all strains at different concentrations regardless of metabolic activity.

Conclusion

Verbenalin did not show any signs of mutagenicity in this study. Additional toxicity studies including repeated oral toxicity, reproductive toxicity, and carcinogenicity tests are needed.

Review of Drug Therapy for Peripheral Facial Nerve Regeneration That Can Be Used in Actual Clinical Practice

Although facial nerve palsy is not a life-threatening disease, facial asymmetry affects interpersonal relationships, causes psychological stress, and devastates human life. The treatment and rehabilitation of facial paralysis has many socio-economic costs. Therefore, in cases of facial paralysis, it is necessary to identify the cause and provide the best treatment. However, until now, complete recovery has been difficult regardless of the treatment used in cases of complete paralysis of unknown cause and cutting injury of the facial nerve due to disease or accident. Therefore, this article aims to contribute to the future treatment of facial paralysis by reviewing studies on drugs that aid in nerve regeneration after peripheral nerve damage.

The Use of Ginkgo Biloba L. as a Neuroprotective Agent in the Alzheimer's Disease

Alzheimer's disease, a neurodegenerative disease, is one of the most common causes of dementia if elderly people worldwide. Alzheimer's disease leads to the alienation of individuals and their exclusion from social and professional life. It is characterized mainly by the degradation of memory and disorientation, which occurs as a result of the loss of neuronal structure and function in different brain areas. In recent years, more and more attention has been paid to use in the treatment of natural bioactive compounds that will be effective in neurodegenerative diseases, including Alzheimer's disease. G. biloba L. and its most frequently used standardized extract (EGb 761), have been used for many years in supportive therapy and in the prevention of cognitive disorders. The paper presents an overview of reports on the pathogenesis of Alzheimer's disease, as well as a summary of the properties of G. biloba extract and its effects on the possible pathogenesis of the disease. By exploring more about the pathogenesis of the disease and the benefits of G. biloba extract for patients with Alzheimer's disease, it will be possible to create an individualized therapeutic protocol to optimize the treatment.

Antitumor Effects of Freeze-Dried Robusta Coffee (Coffea canephora) Extracts on Breast Cancer Cell Lines

Coffee consumption is believed to have chemopreventive and chemotherapeutic effects and to contribute to preventing the development and progression of cancer. However, there is still controversy around these claims. As indicated in our previous works, diet can influence the risk of breast cancer. Intake of coffee is hypothesized to reduce this risk, but current scientific evidence is not conclusive. This work is aimed at studying the effects of Robusta coffee bean extract on cell viability, proliferation, and apoptosis of different human cancers, especially breast cancer cell lines. To this end, cell viability was evaluated by Alamar Blue in 2D and 3D models, the cell cycle by PI, apoptosis by annexin V, mitochondrial morphology, and functionality by mitoTracker, and colony formation capacity by the clonogenic assay. Green and dark coffee extract significantly reduced viability in human breast, colorectal, brain, and bone cancer cells. Coffee anticancer activity was clearly evidenced in MDA-MB-231 (ER⁻) and MCF-7 (ER⁺) breast cancer cells but not in the normal breast cell line. In addition, coffee extract induces an increase S phase and a decrease G2/M population in breast cancer cells, affected the mitochondrial morphology, and triggered apoptosis. MDA-MB-231 breast cancer cells lost their clonogenic capacity after treatment. The antitumor activity was demonstrated in both 2D and 3D culture cell models.

Mild Cognitive Impairment and Mild Dementia: The Role of Ginkgo biloba (EGb 761®)

Mild cognitive impairment (MCI) and dementia are clinically prevalent in the elderly. There is a high risk of cognitive decline in patients diagnosed with MCI or dementia. This review describes the effectiveness of Ginkgo biloba leaf special extract EGb 761^® for the treatment of dementia syndromes and EGb 761^® combination therapy with other medications for symptomatic dementia. This drug has shown convincing results, improving cognitive function, neuropsychiatric symptoms and consequent reduction of caregiver stress and maintenance of autonomy in patients with age-related cognitive decline, MCI and mild to moderate dementia. Currently, there is little evidence to support the combination therapy with anti-dementia drugs and, therefore, more evidence is needed to evaluate the role of EGb 761^® in mixed therapy.

Improving Age-Related Cognitive Decline through Dietary Interventions Targeting Mitochondrial Dysfunction

Aging is inevitable and it is one of the major contributors to cognitive decline. However, the mechanisms underlying age-related cognitive decline are still the object of extensive research. At the biological level, it is unknown how the aging brain is subjected to progressive oxidative stress and neuroinflammation which determine, among others, mitochondrial dysfunction. The link between mitochondrial dysfunction and cognitive impairment is becoming ever more clear by the presence of significant neurological disturbances in human mitochondrial diseases. Possibly, the most important lifestyle factor determining mitochondrial functioning is nutrition. Therefore, with the present work, we review the latest findings disclosing a link between nutrition, mitochondrial functioning and cognition, and pave new ways to counteract cognitive decline in late adulthood through diet.

Treating Senescence like Cancer: Novel Perspectives in Senotherapy of Chronic Diseases

The WHO estimated around 41 million deaths worldwide each year for age-related non-communicable chronic diseases. Hence, developing strategies to control the accumulation of cell senescence in living organisms and the overall aging process is an urgently needed problem of social relevance. During aging, many biological processes are altered, which globally induce the dysfunction of the whole organism. Cell senescence is one of the causes of this modification. Nowadays, several drugs approved for anticancer therapy have been repurposed to treat senescence, and others are under scrutiny in vitro and in vivo to establish their senomorphic or senolytic properties. In some cases, this research led to a significant increase in cell survival or to a prolonged lifespan in animal models, at least. Senomorphics can act to interfere with a specific pathway in order to restore the appropriate cellular function, preserve viability, and to prolong the lifespan. On the other hand, senolytics induce apoptosis in senescent cells allowing the remaining non–senescent population to preserve or restore tissue function. A large number of research articles and reviews recently addressed this topic. Herein, we would like to focus attention on those chemical agents with senomorphic or senolytic properties that perspectively, according to literature, suggest a potential application as senotherapeutics for chronic diseases.

Emerging senolytic agents derived from natural products

Cellular senescence is a hallmark of aging, it is a permanent state of cell cycle arrest induced by cellular stresses. During the aging process, senescent cells (SCs) increasingly accumulate in tissues, causing a loss of tissue-repair capacity because of cell cycle arrest in progenitor cells and produce proinflammatory and matrix-degrading molecules which are known as the senescence-associated secretory phenotype (SASP), and thereby contribute to the development of various age-related diseases. Genetic evidence has demonstrated that clearance of SCs can delay aging and extend healthspan. Senolytics, small molecules that can selectively kill SCs, have been developed to treat various age-related diseases. In recent years, emerging natural compounds have been discovered to be effective senolytic agents, such as quercetin, fisetin, piperlongumine and the curcumin analog. Some of the compounds have been validated in animal models and have great potential to be pushed to clinical applications. In this review, we will discuss cellular senescence and its potential as a target for treating age-related diseases, and summarize the known natural compounds as senolytic agents and their applications.

Mitochondrial Function, Dynamics, and Permeability Transition: A Complex Love Triangle as A Possible Target for the Treatment of Brain Aging and Alzheimer's Disease

Because of the failure of all amyloid-β directed treatment strategies for Alzheimer's disease (AD), the concept of mitochondrial dysfunction as a major pathomechanism of the cognitive decline in aging and AD has received substantial support. Accordingly, improving mitochondrial function as an alternative strategy for new drug development became of increasing interest and many different compounds have been identified which improve mitochondrial function in preclinical in vitro and in vivo experiments. However, very few if any have been investigated in clinical trials, representing a major drawback of the mitochondria directed drug development. To overcome these problems, we used a top-down approach by investigating several older antidementia drugs with clinical evidence of therapeutic efficacy. These include EGb761® (standardized ginkgo biloba extract), piracetam, and Dimebon. All improve experimentally many aspects of mitochondrial dysfunction including mitochondrial dynamics and also improve cognition and impaired neuronal plasticity, the functionally most relevant consequences of mitochondrial dysfunction. All partially inhibit opening events of the mitochondrial permeability transition pore (mPTP) which previously has mainly been discussed as a mechanism relevant for the induction of apoptosis. However, as more recent work suggests the mPTP as a master regulator of many mitochondrial functions, our data suggest the mPTP as a possible relevant drug target within the love triangle between mPTP regulation, mitochondrial dynamics, and mitochondrial function including regulation of neuronal plasticity. Drugs interfering with mPTP function will improve not only mitochondrial impairment in aging and AD but also will have beneficial effects on impaired neuronal plasticity, the pathomechanism which correlates best with functional deficits (cognition, behavior) in aging and AD.

Therapeutic efficacy of the Ginkgo special extract EGb761® within the framework of the mitochondrial cascade hypothesis of Alzheimer's disease

OBJECTIVES

The mitochondrial cascade hypothesis of dementia assumes mitochondrial dysfunction as an important common pathomechanism for the whole spectrum of age-associated memory disorders from cognitive symptoms in the elderly over mild cognitive impairment to Alzheimer's dementia. Thus, a drug such as the Ginkgo special extract EGb 761^® which improves mitochondrial function should be able to ameliorate cognitive deficits over the whole aging spectrum.

METHODS

We review the most relevant publications about effects of EGb 761^® on cognition and synaptic deficits in preclinical studies as well as on cognitive deficits in man from aging to dementia.

RESULTS

EGb 761^® improves mitochondrial dysfunction and cognitive impairment over the whole spectrum of age-associated cognitive disorders in relevant animal models and in vitro experiments, and also shows clinical efficacy in improving cognition over the whole range from aging to Alzheimer's or even vascular dementia.

CONCLUSIONS

EGb 761^® shows clinical efficacy in the treatment of cognitive deficits over the whole spectrum of age-associated memory disorders. Thus, EGb 761^® can serve as an important pharmacological argument for the mitochondrial cascade hypothesis of dementia.

Ginkgo biloba extract EGb 761® in the symptomatic treatment of mild-to-moderate dementia: a profile of its use

EGb 761^® (Tanakan^®) is a standardized extract of Ginkgo biloba leaves that has demonstrated protective properties against neuronal and vascular damage. Overall, in randomized, placebo-controlled clinical trials and meta-analyses in adults with mild-to-moderate dementia, EGb 761^® displayed positive effects, with changes from baseline in outcomes related to cognition, behaviour and global change that are generally better than those shown with placebo. EGb 761^® is generally well tolerated, with no safety issues being identified during its many years of widespread use.

Mitochondria as pharmacological targets in Down syndrome

Mitochondria play a pivotal role in cellular energy-generating processes and are considered master regulators of cell life and death fate. Mitochondrial function integrates signalling networks in several metabolic pathways controlling neurogenesis and neuroplasticity. Indeed, dysfunctional mitochondria and mitochondrial-dependent activation of intracellular stress cascades are critical initiating events in many human neurodegenerative or neurodevelopmental diseases including Down syndrome (DS). It is well established that trisomy of human chromosome 21 can cause DS. DS is associated with neurodevelopmental delay, intellectual disability and early neurodegeneration. Recently, molecular mechanisms responsible for mitochondrial damage and energy deficits have been identified and characterized in several DS-derived human cells and animal models of DS. Therefore, therapeutic strategies targeting mitochondria could have great potential for new treatment regimens in DS. The purpose of this review is to highlight recent studies concerning mitochondrial impairment in DS, focusing on alterations of the molecular pathways controlling mitochondrial function. We will also discuss the effects and molecular mechanisms of naturally occurring and chemically synthetized drugs that exert neuroprotective effects through modulation of mitochondrial function and attenuation of oxidative stress. These compounds might represent novel therapeutic tools for the modulation of energy deficits in DS.

Extract of Ginkgo biloba exacerbates liver metastasis in a mouse colon cancer Xenograft model

Background

Metastasis refers to the spread of a primary tumor cell from the primary site to other locations in the body and it is generally associated with the severity of a tumor. Extract of Ginkgo biloba (EGb) contains various bioactive compounds and it exerts beneficial effects including improvements in brain function and reduced risk of cardiovascular diseases. On the other hand, increased risk of thyroid and liver cancers by EGb have been reported in animals.

Methods

A colon cancer metastasis model was established using intrasplenic injection of a human colon cancer cell line, SW620-luc in athymic mice to investigate the potential impact of EGb on colon cancer progression. After tumor establishment, EGb was intraperitonically injected daily for 5 wks.

Results

EGb significantly increased the rate of metastasis in mouse liver and decreased the number of necrotic and apoptotic cells in the metastatic liver when compared to the control. Meanwhile, EGb significantly induced proliferation of tumor cells in the metastatic liver, indicated by increased staining of Ki67 and H3S10p. mRNA expression of genes involved in cell cycle, metastasis, apoptosis, and oxidative stress were altered by EGb treatment in livers with tumors. Moreover, EGb activated the stress-responsive MAPK pathways in the liver with metastatic tumors.

Conclusions

EGb exacerbated liver metastasis in a mouse colon cancer metastasis model. This is potentially due to the increased tumor cell proliferation involving stimulated MAPK pathways.

Electronic supplementary material

The online version of this article (10.1186/s12906-017-2014-7) contains supplementary material, which is available to authorized users.

Advances in the Studies of Ginkgo Biloba Leaves Extract on Aging-Related Diseases

The prevalence of degenerative disorders in public health has promoted in-depth investigations of the underlying pathogenesis and the development of new treatment drugs. Ginkgo biloba leaves extract (EGb) is obtained from Ginkgo biloba leaves and has been used for thousands of years. In recent decades, both basic and clinical studies have established the effects of EGb. It is widely used in various degenerative diseases such as cerebrovascular disease, Alzheimer's disease, macroangiopathy and more. Here, we reviewed several pharmacological mechanisms of EGb, including its antioxidant properties, prevention of mitochondrial dysfunctions, and effect on apoptosis. We also described some clinical applications of EGb, such as its effect on neuro and cardiovascular protection, and anticancer properties. The above biological functions of EGb are mainly focused on aging-related disorders, but its effect on other diseases remains unclear. Thus, through this review, we aim to encourage further studies on EGb and discover more potential applications.

Fatty Acids, Antioxidants and Physical Activity in Brain Aging

Polyunsaturated fatty acids and antioxidants are important mediators in the central nervous system. Lipid derivatives may control the production of proinflammatory agents and regulate NF-κB activity, microglial activation, and fatty acid oxidation; on the other hand, antioxidants, such as glutathione and ascorbate, have been shown to signal through transmitter receptors and protect against acute and chronic oxidative stress, modulating the activity of different signaling pathways. Several authors have investigated the role of these nutrients in the brains of the young and the aged in degenerative diseases such as Alzheimer’s and Parkinson’s, and during brain aging due to adiposity- and physical inactivity-mediated metabolic disturbances, chronic inflammation, and oxidative stress. Through a literature review, we aimed to highlight recent data on the role of adiposity, fatty acids, antioxidants, and physical inactivity in the pathophysiology of the brain and in the molecular mechanisms of senescence. Data indicate the complexity and necessity of endogenous/dietary antioxidants for the maintenance of redox status and the control of neuroglial signaling under stress. Recent studies also indicate that omega-3 and -6 fatty acids act in a competitive manner to generate mediators for energy metabolism, influencing feeding behavior, neural plasticity, and memory during aging. Finding pharmacological or dietary resources that mitigate or prevent neurodegenerative affections continues to be a great challenge and requires additional effort from researchers, clinicians, and nutritionists in the field.

Brain aging and neurodegeneration: from a mitochondrial point of view

Aging is defined as a progressive time-related accumulation of changes responsible for or at least involved in the increased susceptibility to disease and death. The brain seems to be particularly sensitive to the aging process since the appearance of neurodegenerative diseases, including Alzheimer's disease, is exponential with the increasing age. Mitochondria were placed at the center of the 'free-radical theory of aging', because these paramount organelles are not only the main producers of energy in the cells, but also to main source of reactive oxygen species. Thus, in this review, we aim to look at brain aging processes from a mitochondrial point of view by asking: (i) What happens to brain mitochondrial bioenergetics and dynamics during aging? (ii) Why is the brain so sensitive to the age-related mitochondrial impairments? (iii) Is there a sex difference in the age-induced mitochondrial dysfunction? Understanding mitochondrial physiology in the context of brain aging may help identify therapeutic targets against neurodegeneration. This article is part of a series "Beyond Amyloid".

Ginkgo biloba extract (Egb761) attenuates zinc-induced tau phosphorylation at Ser262 by regulating GSK3β activity in rat primary cortical neurons

In the brain, an excessive amount of zinc promotes the deposition of β-amyloid proteins and the intraneuronal accumulation of neurofibrillary tangles composed of hyperphosphorylated tau proteins. These consequences are key neuropathological traits that reflect Alzheimer's disease. Egb761, a standardized Ginkgo biloba extract, is a powerful antioxidant known to exhibit neuroprotective actions. In this study, we investigated whether Egb761 can counteract the zinc-induced tau phosphorylation in rat primary cortical neurons. To determine the modification of tau phosphorylation by Egb761 treatment, we conducted Western blot analyses, MTT assay, ROS measurements and immunocytochemistry. We found that zinc-induced tau phosphorylation occurred at Ser262 in a time- and dose-dependent manner while other tau sites were not phosphorylated. Tau phosphorylation at Ser262 was increased 30 min after zinc treatment and peaked 3 h after zinc treatment (control: 100 ± 1.2%, 30 min: 253 ± 2.24%, 3 h: 373 ± 1.3%). Interestingly, Egb761 treatment attenuated the zinc-induced tau hyperphosphorylation at Ser262 in a concentration-dependent manner while the antioxidant N-acetylcysteine showed a similar effect. Furthermore, Egb761 prevented the zinc-induced activation of p38 MAPK and GSK3β, as well as the zinc-induced increase in ROS production and neuronal cell death. Lithium chloride also inhibited the zinc-induced tau phosphorylation but did not affect ROS levels. These results suggest the potential of Egb761 for inhibiting the zinc-induced tau phosphorylation at Ser262 through its anti-oxidative actions involving the regulation of GSK3β. Therefore, Egb761 may be a candidate for the treatment of tauopathy present in neurological disorders such as Alzheimer's disease.

Medicinal herbs and therapeutic drugs interactions

People mistakenly think that all herbs are safe, because of the fact that they are natural, and the use of herbal medication is growing. Aspects of the efficacy, safety, and quality of herbal or natural products are the subjects of on-going debates. Concurrent administration of herbs may interfere with the effect of drugs. Lack of knowledge of the interaction potential together with an underreporting of herbal use poses a challenge for health care providers and a safety concern for patients. A good understanding of the mechanisms of herb-drug interactions is also essential for assessing and minimizing clinical risks. Examples of herbal medicine-pharmaceutical drug interactions of commonly used herbs are presented. The potential pharmacokinetic and pharmacodynamic basis of such interactions is discussed, as well as the challenges associated with the identification and prediction of herb-drug interactions.

Anti-ischaemic effects of bilobalide on neonatal rat cardiomyocytes and the involvement of the platelet-activating factor receptor

Terpene trilactones from Ginkgo biloba have been investigated extensively for their antioxidant and anti-ischaemic activities on the brain and the heart, but the mechanisms of these effects remain unclear. For the present study, a terpenoid constituent from G. biloba, bilobalide, was screened for protective effects on the ischaemic heart and the involvement of the PAFR [PAF (platelet-activating factor) receptor] and the enzyme that degrades PAF, PAF-AH (PAF acetylhydrolase) during hypoxia. The PAF pathway is supposed to play a role in hypoxia and its regulation may prevent or alleviate MI (myocardial infarction). Cardiomyocytes from neonatal rat hearts were cultured and treated with different concentrations of bilobalide (500–0.5 ng/ml). After being subjected to a hypoxic environment, the cells' viability was evaluated and proteins as well as RNA were extracted for analysis by Western blotting and RT–PCR (reverse transcription PCR) respectively. With the MI model we tested for bilobalide's cardioprotective effects and the involvement of PAFR and PAF-AH. Bilobalide (5 ng/ml) significantly decreased the mortality of cells in a concentration-dependent way. mRNA expression of PAFR was up-regulated in hypoxic cells but in the groups treated with bilobalide, its expression was down-regulated to the level of the normal control. In hypoxic tissue, PAFR protein expression was also up-regulated, but was reduced in the bilobalide (10 mg/kg of body weight) treated group. Our results indicate that PAF and its receptor may be involved in the cellular response of cardiomyocytes to hypoxia and that bilobalide may interact with this receptor to exert its cardioprotective effects.

Radioprotectors - the evergreen topic

To protect organisms from ionizing radiation (IR), and to reduce morbidity or mortality, various agents, called radioprotectors, have been utilized. Because radiation-induced cellular damage is attributed primarily to the harmful effects of free radicals, molecules with radical-scavenging properties are particularly promising as radioprotectors. Early development of such agents focused on thiol synthetic compounds, known as WR protectors, but only amifostine (WR-2721) has been used in clinical trials as an officially approved radioprotector. Besides thiol compounds, various compounds with different chemical structure were investigated, but an ideal radioprotector has not been found yet. Plants and natural products have been evaluated as promising sources of radioprotectors because of their low toxicity, although they exhibit an inferior protection level compared to synthetic thiol compounds. Active plant constituents seem to exert the radioprotection through antioxidant and free radical-scavenging activities. Our research established that plants containing polyphenolic compounds (raspberry, blueberry, strawberry, grape, etc.) exhibit antioxidative activities and protect genetic material from IR.

Mitochondrial energy metabolism and redox signaling in brain aging and neurodegeneration

SIGNIFICANCE

The mitochondrial energy-transducing capacity is essential for the maintenance of neuronal function, and the impairment of energy metabolism and redox homeostasis is a hallmark of brain aging, which is particularly accentuated in the early stages of neurodegenerative diseases.

RECENT ADVANCES

The communications between mitochondria and the rest of the cell by energy- and redox-sensitive signaling establish a master regulatory device that controls cellular energy levels and the redox environment. Impairment of this regulatory devise is critical for aging and the early stages of neurodegenerative diseases.

CRITICAL ISSUES

This review focuses on a coordinated metabolic network-cytosolic signaling, transcriptional regulation, and mitochondrial function-that controls the cellular energy levels and redox status as well as factors which impair this metabolic network during brain aging and neurodegeneration.

FUTURE DIRECTIONS

Characterization of mitochondrial function and mitochondria-cytosol communications will provide pivotal opportunities for identifying targets and developing new strategies aimed at restoring the mitochondrial energy-redox axis that is compromised in brain aging and neurodegeneration.

Protective effect of curcuminoids on age-related mitochondrial impairment in female Wistar rat brain

The present study demonstrated the neuroprotective effect of curcuminoids, the active polyphenols of Curcuma longa (L.) rhizomes on mitochondrial dysfunctioning in middle aged and aged female Wistar rat brain. Rats were orally treated with curcuminoids (100 mg/kg) for 3 months and their brain was collected for evaluation of mitochondrial enzymes and complexes activity, ultra structural changes in mitochondria, neuronal nitric oxide synthase (nNOS) protein expression, adenosine triphosphate (ATP) and lipofuscin content. Significant alterations were observed in all the tested parameters in highly aged rat brain when compared with young control. Long term curcuminoids administration prevented this age associated loss of mitochondrial enzymes and complexes activity in middle aged rat brain except for malate dehydrogenase, Complex II and IV activity when compared with young control. Among aged rats, curcuminoids treatment specifically elevated isocitrate and NADH dehydrogenase, cytochrome c oxidase, Complex I and total ATP content. A significant down-regulation of nNOS protein expression along with reduced lipofuscin content was also observed in curucminoids treated middle aged and aged rats. Thus, it was suggested that curcuminoids may act as a putative drug candidate for the prevention of deleterious effects of ageing and age associated neurodegenerative disorders through amelioration of aberrant mitochondrial functioning.

Antiapoptotic Effects of EGb 761

Ginkgo biloba extracts have long been used in Chinese traditional medicine for hundreds of years. The most significant extract obtained from Ginkgo biloba leaves has been EGb 761, a widely used phytopharmaceutical product in Europe. EGb 761 is a well-defined mixture of active compounds, which contains two main active substances: flavonoid glycosides (24-26%) and terpene lactones (6-8%). These compounds have shown antiapoptotic effects through the protection of mitochondrial membrane integrity, inhibition of mitochondrial cytochrome c release, enhancement of antiapoptotic protein transcription, and reduction of caspase transcription and DNA fragmentation. Other effects include the reduction of oxidative stress (which has been related to the occurrence of vascular, degenerative, and proliferative diseases), coupled to strong induction of phase II-detoxifying and cellular defense enzymes by Nrf2/ARE activation, in addition to the modulation of transcription factors, such as CREB, HIF-1 α , NF- κ B, AP-1, and p53, involved in the apoptosis process. This work reviews experimental results about the antiapoptotic effects induced by the standardized extract of Ginkgo biloba leaves (EGb 761).

Neurodegeneration after transient brain ischemia in aged mice: beneficial effects of bilobalide

Bilobalide, an active constituent of Ginkgo biloba, has neuroprotective properties in experimental stroke models, but nearly all published studies were carried out in young animals. As ischemic strokes in humans are much more frequent in old age, we investigated bilobalide's effects in aged mice (age 18-22 month) using a model of transient ischemia induced by occlusion of the middle cerebral artery (MCAO) for 60 min. When bilobalide was administered locally into the striatum via microdialysis, a significant reduction of infarct size by almost 70% was observed. Concomitantly, the extensive, twelve-fold increase of extracellular glutamate which was observed in untreated animals was strongly reduced during the infusion of bilobalide. Glucose levels, in contrast, were not affected by bilobalide. In further experiments, bilobalide was given as an intraperitoneal injection (10/mg/kg) 1h before MCAO onset. ATP levels (measured in brain homogenates) were significantly reduced by transient MCAO but pretreatment with bilobalide prevented this loss. In ex vivo experiments with isolated mitochondria from aged mice, we found that the activity of the mitochondrial respiratory chain was only slightly impaired after 60 min of ischemia, and bilobalide showed no benefit in this experiment. However, aged mitochondria proved to be very sensitive to calcium-induced swelling which was significantly increased after ischemia. In this assay, pretreatment with bilobalide lowered the extent of swelling nearly to control levels. In behavioural tests, pretreatment of aged mice with bilobalide significantly improved the outcome in the Rotarod and the Corner test. In conclusion, aged mice show some differences in their response to transient ischemia when compared with young mice. Bilobalide has prominent neuroprotective properties in mice of all ages.

The effects of multivitamin supplementation on mood and general well-being in healthy young adults. A laboratory and at-home mobile phone assessment

Previous research has suggested that multivitamin (MV) supplementation may be associated with beneficial effects for mood and general well-being, although treatment durations have typically been less than 90 days, samples have often been restricted to males only and acute effects have not been adequately differentiated from chronic effects. In the current study a MV supplement containing high levels of B-vitamins was administered daily to 138 healthy young adult participants between the ages of 20 and 50 years over a 16-week period. Chronic mood measures (GHQ-28, POMS, Chalder fatigue, PILL, Bond-Lader and custom visual analogue scales) were administered pre-dose at baseline, 8- and 16-weeks. Changes in Bond-Lader and VAS in response to a multi-tasking framework (MTF) were also assessed at 8- and 16-weeks. For a subset of participants, at-home mobile-phone assessments of mood were assessed on a weekly basis using Bond-Lader and VAS. No significant treatment effects were found for any chronic laboratory mood measures. In response to the MTF, a significant treatment x time interaction was found for STAI-S, with a trend towards a greater increase in stress ratings for male participants in the MV group at 16 weeks. However, this finding may have been attributable to a larger proportion of students in the male MV group. In contrast, at-home mobile-phone assessments, where assessments were conducted post-dose, revealed significantly reduced stress, physical fatigue and anxiety in the MV group in comparison to placebo across a number of time points. Further research using both acute and chronic dosing regimens are required in order to properly differentiate these effects.

Effect of aging on mitochondrial and nuclear DNA oxidative damage in the heart and brain throughout the life-span of the rat

The oxygen radical-induced DNA lesion 8-oxo,7,8-dihydro-2'-deoxyguanosine (8-oxodG) is the most commonly measured marker of oxidative DNA damage, which is currently considered a main cause of aging. However, a detailed study of the age-related variations of this marker in both mitochondrial (mtDNA) and nuclear (nDNA) DNA of post-mitotic organs throughout the life span has not been previously performed. In this investigation 8-oxodG steady-state levels were simultaneously measured in mtDNA and nDNA in the heart and brain of Sprague-Dawley rats at up to five different ages covering most of the adult life span, 4, 8, 12, 17 and 24 months of age, using exactly the same digestion of DNA to deoxynucleosides and chromatographic procedures for mtDNA and nDNA. 8-oxodG levels were maintained without changes during young and middle age in all cases, but showed statistically significant increases at the older ages studied in the majority of the kinds of DNA investigated. These age-related increases in oxidative damage occurred in brain nDNA at 17 and 24 months of age, in heart nDNA at 24 months of age, and in brain mtDNA at 24 months of age, whereas no significant age-related changes were detected in heart mtDNA. Besides, 8-oxodG levels were various fold higher in mtDNA than in nDNA, both in brain and heart, at all the ages studied. The results show that oxidative damage to DNA is higher in the mtDNA than in the nDNA of post-mitotic tissues throughout the whole life span of the rat and that and increase in mtDNA and nDNA oxidative stress occurs in most cases in old animals.

Research progress on flavonoids isolated from traditional Chinese medicine in treatment of Alzheimer's disease

Alzheimer's disease (AD) is a severe condition in aging countries. The currently used drugs including donepezil, rivastigmine, galantamine, and memantine are effective in managing the symptoms. However, they are hardly capable of preventing, halting, or reversing the disease. In the long history of development of traditional Chinese medicine, much experience has accumulated and is summarized in treatment of diseases that correspond to the concept of AD. In recent years, exploration of natural active ingredients from medicinal herbs for treatment of AD has attracted substantial attention. Some flavonoids have been revealed to have a variety of biological actions such as scavenging free radicals, inhibiting neuron apoptosis, and nurturing neuronal cells that constitute the basis for treatment of AD. In this article, we review recent research progress on flavonoids isolated from traditional Chinese medicine against AD and their underlying mechanisms.

Ginkgo biloba extract reduces high-glucose-induced endothelial reactive oxygen species generation and cell adhesion molecule expression by enhancing HO-1 expression via Akt/eNOS and p38 MAP kinase pathways

AIM

Hyperglycemia is one of the major risk factors leading to vascular complications in clinical diabetes mellitus. Ginkgo biloba extract (GBE), an antioxidant herbal medicine, possesses anti-inflammatory effects. We examined whether GBE can reduce high glucose-induced endothelial adhesiveness to monocytes, an in vitro sign mimicking in vivo early atherogenesis, through selective regulation of heme oxygenase (HO)-1 expression.

METHODS

Human aortic endothelial cells (HAECs) were cultured with normal glucose or high glucose (25 mM) for 4 days and subsequently combined with GBE (EGb761, Dr. Willmar Schwabe, Karlsruhe, Germany) treatment in the last 18 h of the 4-day period. The endothelial reactive oxygen species (ROS) generation, adhesion molecule expression and the adhesiveness to monocytes were examined. The specific signal pathways such as HO-1 were also examined.

RESULTS

High glucose increased ROS generation, adhesion molecule expression and the adhesiveness to monocytes in HAECs. These high glucose-induced phenomena could be suppressed by GBE (100 μg/ml)-induced HO-1 expression in a dose-dependent and time-dependent manner. In addition, jun N-terminal kinases inhibitor or phosphoinositide 3 kinase inhibitor could reduce GBE-induced HO-1 expression. Furthermore, HO-1 inhibitor, HO-1 siRNA, endothelial nitric oxide synthase (eNOS) siRNA, or nuclear factor erythroid 2-related factor (Nrf) 2 siRNA blocked the cytoprotective effects of GBE. Meanwhile, p38/mitogen-activated protein kinase (MAPK) inhibitor could also reduce the effects of GBE on HO-1 induction.

CONCLUSION

GBE could reduce high glucose-induced endothelial adhesion via enhancing HO-1 expression through the Akt/eNOS and p38/MAPK pathways. Our findings suggest a potential strategy targeting on HO-1 induction by GBE for endothelial protection in the presence of high glucose such as that in diabetes mellitus.

Influence of ethanol extract of Ginkgo biloba leaves on the isolated rat heart work and mitochondria functions

In this study, we attempted to elucidate whether the effects of ethanol extract of Ginkgo biloba leaves (GBE) observed previously on isolated rat heart mitochondria may be realized in situ (in case of isolated heart perfused under normal conditions and under ischemia-reperfusion). We found that GBE at low concentrations (0.01, 0.05, and 0.1 μL/mL) does not affect the heart rate and parameters of electrocardiogram (ECG) but produces a small increase in the coronary flow. Higher concentration of GBE (0.2 and 0.3 μL/mL) diminished the heart rate, decreased the coronary flow, and tended to enhance the parameters of ECG. The contractility of isolated rat heart and mitochondrial nicotinamide adenine dinucleotide reduced form fluorescence decreased in a GBE concentration-dependent manner. Mitochondria isolated from hearts pre-perfused with GBE (0.05 μL/mL) for 20 minutes before nonflow global ischemia-reperfusion (45 min/15 min) showed higher respiratory rates with pyruvate + malate in state 2 and state 3, higher respiratory control index, and diminished H₂O₂ generation compared with untreated group. Higher GBE concentration, 0.4 μL/mL, had no effect on H2O2 generation and did not prevent the ischemia-reperfusion-induced decrease of pyruvate + malate oxidation in state 3 but even enhanced it. However, in the case of nonischemic perfusions, this GBE concentration had no significant effect on these parameters of respiratory functions of isolated heart mitochondria.

Effect of a phytopharmaceutical medicine, Ginko biloba extract 761, in an animal model of Parkinson's disease: therapeutic perspectives

Ginkgo Biloba extract 761 (EGb 761) is a patented and well-defined mixture of active compounds extracted from Ginkgo biloba leaves. This extract contains two main groups of active compounds, flavonoids (24%) and terpenoids (6%). EGb 761 is used clinically to treat dementia and vaso-occlusive and cochleovestibular disorders. This extract has neuroprotective effects, exerted probably by means of its antioxidant function. Parkinson's disease (PD) is a neurodegenerative disorder that affects 2% of the population older than 60 y. It produces a progressive loss of dopaminergic neurons and depletion of dopamine (DA), leading to movement impairment. The production of reactive oxygen species, which act as mediators of oxidative damage, is linked to PD. This disease is routinely treated with the DA precursor, L-3,4-dihydroxyphenylalanine. However, this produces severe side effects, and its neurotoxic properties can be due to a free radical production. Thus, administration of antioxidant drugs might be used to prevent neuronal death produced by oxidative mechanisms. The use of synthetic antioxidants has decreased because of their suspected activity as carcinogenic promoters. We describe the studies related to the antioxidant effect of EGb 761 in an animal model of PD. It has been shown that EGb761 can provide a neuroprotective/neurorecovery effect against the damage to midbrain DA neurons in an animal model of PD. EGb 761 also has been found to lessen the impairment of locomotion, correlating with an increase of DA and other morphologic and biochemical parameters related to its antioxidant effect in an animal model of PD. These studies suggest it as an alternative in the future treatment of PD.

Ginkgo biloba extract reduces high-glucose-induced endothelial adhesion by inhibiting the redox-dependent interleukin-6 pathways

BACKGROUND

Chronic elevation of glucose level activates vascular inflammation and increases endothelial adhesiveness to monocytes, an early sign of atherogenesis. This study aimed to elucidate the detailed mechanisms of high-glucose-induced endothelial inflammation, and to investigate the potential effects of Ginkgo biloba extract (GBE), an antioxidant herbal medicine, on such inflammation.

MATERIALS AND METHODS

Human aortic endothelial cells were cultured in high glucose or mannitol as osmotic control for 4 days. The expression of cytokines and adhesion molecules and the adhesiveness of endothelial cells to monocytes were examined. The effects of pretreatment of GBE or N-acetylcysteine, an antioxidant, were also investigated.

RESULTS

Either high glucose or mannitol significantly increased reactive oxygen species (ROS) production, interleukin-6 secretion, intercellular adhesion molecule-1 (ICAM-1) expression, as well as endothelial adhesiveness to monocytes. The high-glucose-induced endothelial adhesiveness was significantly reduced either by an anti-ICAM-1 antibody or by an interleukin-6 neutralizing antibody. Interleukin-6 (5 ng/ml) significantly increased endothelial ICAM-1 expression. Piceatannol, a signal transducer and activator of transcription (STAT) 1/3 inhibitor, but not fludarabine, a STAT1 inhibitor, suppressed high-glucose-induced ICAM-1 expression. Pretreatment with GBE or N-acetylcysteine inhibited high-glucose-induced ROS, interleukin-6 production, STAT1/3 activation, ICAM-1 expression, and endothelial adhesiveness to monocytes.

CONCLUSIONS

Long-term presence of high glucose induced STAT3 mediated ICAM-1 dependent endothelial adhesiveness to monocytes via the osmotic-related redox-dependent interleukin-6 pathways. GBE reduced high-glucose-induced endothelial inflammation mainly by inhibiting interleukin-6 activation. Future study is indicated to validate the antioxidant/anti-inflammatory strategy targeting on interleukin-6 for endothelial protection in in vivo and clinical hyperglycemia.

New insights in the amyloid-Beta interaction with mitochondria

Biochemical and morphological alterations of mitochondria may play an important role in the pathogenesis of Alzheimer's disease (AD). Particularly, mitochondrial dysfunction is a hallmark of amyloid-beta-induced neuronal toxicity in Alzheimer's disease. The recent emphasis on the intracellular biology of amyloid-beta and its precursor protein (APP) has led researchers to consider the possibility that mitochondria-associated and mitochondrial amyloid-beta may directly cause neurotoxicity. Both proteins are known to localize to mitochondrial membranes, block the transport of nuclear-encoded mitochondrial proteins to mitochondria, interact with mitochondrial proteins, disrupt the electron transport chain, increase reactive oxygen species production, cause mitochondrial damage, and prevent neurons from functioning normally. In this paper, we will outline current knowledge of the intracellular localization of amyloid-beta. Moreover, we summarize evidence from AD postmortem brain as well as animal AD models showing that amyloid-beta triggers mitochondrial dysfunction through a number of pathways such as impairment of oxidative phosphorylation, elevation of reactive oxygen species production, alteration of mitochondrial dynamics, and interaction with mitochondrial proteins. Thus, this paper supports the Alzheimer cascade mitochondrial hypothesis such as the most important early events in this disease, and probably one of the future strategies on the therapy of this neurodegenerative disease.

Proposed remedies for some developmental disorders

Developmental disorders (DDs) are important leading cause of disability in developed countries and also in the United States. DDs are a group of individual conditions that result from abnormal nervous system development and cause altered function. They can begin at any time from prenatal to 22 years of age and the disability usually presents itself throughout a person's life time. Down syndrome, autism, neural tube defects, schizophrenia, cretinism, and attention-deficit hyperactivity disorder are among the most common DDs that currently plague numerous countries and have varying incidence rates. Their occurrence may be partially attributable to the lack of certain dietary nutrients. Notably, essential vitamins, minerals, and ω-3 fatty acids are often deficient in the general population of America and developed countries and are exceptionally deficient in patients suffering from mental disorders. Typically, most of these disorders are treated with prescription drugs, but many of these drugs cause unwanted side effects. Therefore, psychiatrists recommend alternative or complementary nutritional remedies to overcome the adverse effects of those drugs. Studies have shown that daily supplements of vital nutrients, such as that contain amino acids, often effectively reduce symptoms of the patients, because they are converted into neurotransmitters that alleviate depression and other mental disorders. The aim of this article is to discuss the role of dietary imbalances in the incidence of DD and to emphasize which dietary supplements can aid in the treatment of the above-mentioned DD.

The protective effects of Ginkgo biloba extract (EGb-761) on radiation-induced dermatitis: an experimental study

BACKGROUND

Irradiation of the skin induces production of free radicals, resulting in oxidative stress. EGb-761, an extract from the leaves of the Ginkgo biloba tree, has been reported to be an effective exogenous antioxidant based on its free-radical scavenger properties.

AIM

To investigate the protective effect of G. biloba extract (EGb-761) on radiation-induced dermatitis in rats.

METHODS

Forty male Wistar rats were divided equally into four groups: group 1 received sham radiotherapy (RT) without EGb-761, group 2 received sham RT with EGb-761, group 3 received RT without EGb-761, and group 4 received RT with EGb-761. Levels of malondialdehyde (MDA), nitric oxide (NOx) and glutathione (GSH) were measured. Dermatitis was assessed with a semiquantitative dermatitis item score. The intensity of staining and diffusion of expression for proliferating cellular nuclear antigen (PCNA) and transforming growth factor (TGF)-β3 were also evaluated.

RESULTS

The enhanced oxidative stress seen after RT was markedly diminished when EGb-761 was administered with RT; significantly lower mean MDA (P < 0.005) and higher mean GSH (P < 0.001) levels were seen in group 4 compared with group 3. Although there was a decrease in NOx levels, this was not significant. All (100%) of the animals in group 3 developed dermatitis, whereas only 13% of the animals in group 4 did so (P < 0.0001). There was a significant difference between group 1 and group 3 in PCNA and TGF-β3 staining (P < 0.05), whereas no difference was seen between groups 3 and 4; however, the intensity of staining and diffusion of expression were lower in group 4 than in group 3.

CONCLUSIONS

Prophylactic administration of EGb-761 seems to have a protective effect against radiation-induced dermatitis.

Flavonoids in prevention of diseases with respect to modulation of Ca-pump function

Flavonoids, natural phenolic compounds, are known as agents with strong antioxidant properties. In many diseases associated with oxidative/nitrosative stress and aging they provide multiple biological health benefits. Ca²⁺-ATPases belong to the main calcium regulating proteins involved in the balance of calcium homeostasis, which is impaired in oxidative/nitrosative stress and related diseases or aging. The mechanisms of Ca²⁺-ATPases dysfunction are discussed, focusing on cystein oxidation and tyrosine nitration. Flavonoids act not only as antioxidants but are also able to bind directly to Ca²⁺-ATPases, thus changing their conformation, which results in modulation of enzyme activity.

Dysfunction of Ca²⁺-ATPases is summarized with respect to their posttranslational and conformational changes in diseases related to oxidative/nitrosative stress and aging. Ca²⁺-ATPases are discussed as a therapeutic tool and the possible role of flavonoids in this process is suggested.

Antidepressant-like effect of a Ginkgo biloba extract (EGb761) in the mouse forced swimming test: role of oxidative stress

EGb761 is a well-defined mixture of active compounds extracted from Ginkgo biloba leaves. This extract is used clinically due to its neuroprotective effects, exerted probably via its potent antioxidant or free radical scavenger action. Previous studies suggest that oxidative stress, via free radical production, may play an important role in depression and animal models for depression-like behavior. Preclinical studies have suggested that antioxidants may have antidepressants properties. The aim of this study was to investigate the antidepressant-like of EGb761 due to its antioxidant role against oxidative stress induced in the forced swimming test, the most widely used preclinical model for assessing antidepressant-like behavior. Male BALB/c mice were pretreated with EGb761 (10mg/kg, ip) daily for 17 days followed by the forced swimming test and spontaneous locomotor activity. Animals were sacrificed to evaluate lipid peroxidation, different antioxidant enzyme activities, serotonin and dopamine content in midbrain, hippocampus and prefrontal cortex. EGb761 significantly decreased the immobility time (39%) in the forced swimming test. This antidepressant-like effect of EGb761 was associated with a reduction in lipid peroxidation and superoxide radical production (indicated by a downregulation of Mn-superoxide dismutase activity), both of which are indicators of oxidative stress. The protective effect of EGb761 is not related to excitatory or inhibitory effects in locomotor activity, and was also associated with the modulation of serotonergic and dopaminergic neurotransmission. It is suggested that EGb761 produces an antidepressant-like effect, and that an antioxidant effect against oxidative stress may be partly responsible for its observed neuroprotective effects.

The role of the dorsal hippocampus on the Ginkgo biloba facilitation effect of fear extinction as assessed with fear-potentiated startle

RATIONALE

Ginkgo biloba extract, EGb761, is widely used as herbal supplements throughout Western society. It has been used in the treatment of various common geriatric complaints including short-term memory loss. Our previous study has shown that acute systemic administration of EGb761 enhanced extinction of fear-potentiated startle (FPS) in rats. Little is known about the behavioral effects of hippocampally administered EGb761 on the extinction of FPS.

OBJECTIVE

The current study was performed to evaluate the involvement of the dorsal hippocampus (DH) in the EGb761 facilitation effect on the extinction of FPS.

METHODS AND RESULT

Male adult SD rats were used. EGb761 (28 ng/side, bilaterally) was infused into DH bilaterally 10 min prior to extinction training. Animals were then tested for FPS 24 h later. Results showed that intra-hippocampal infusion of EGb761 prior to extinction training facilitated extinction, which was not due to impairments of expression of conditioned fear. Intra-hippocampal injection of ERK1/2 inhibitor PD98059 partially attenuates the above EGb761 effect. Therefore, acute EGb761 administration modulated extinction of conditioned fear, which might be mediated by more than one signal cascade.

CONCLUSIONS

These results suggest that DH may participate in the facilitation effect of EGb761 on the extinction of conditioned fear. In addition to ERK1/2, another signal cascade may also be involved in the EGb761 facilitation effect on extinction.

Age and sex-related changes in rat brain mitochondrial function

Aging is responsible for the decline in the function of mitochondria and their increase in size and number--adaptive mechanism to restore mitochondrial function. Estrogens increase mitochondrial function, especially in female rats. The aim of this study was to determine the age-related changes in rat brain mitochondrial function focusing on sex differences. Cellular and mitochondrial protein and DNA content, mitochondrial oxidative and phosphorylative function in male and female rat brain from four different age groups (6, 12, 18 and 24 months old) were analyzed. Mitochondria protein/DNA content decreased with aging shifting toward lesser mitochondrial functional capacity and the mitochondria number increased. A sex dimorphism was determined, with female rat brain showing mitochondria with greater functional capacity than males. These sex differences gradually increased during aging.

Heme oxygenase 1, beneficial role in permanent ischemic stroke and in Gingko biloba (EGb 761) neuroprotection

Ginkgo biloba extract, EGb 761, a popular and standardized natural extract, contains 24% ginkgo-flavonol glycosides and 6% terpene lactones. EGb 761 is used worldwide to treat many ailments, and although a number of studies have shown its neuroprotective properties, the mechanisms of action have not been elucidated fully. We hypothesize that EGb 761 and some of its bioactive components [Bilobalide (BB), Ginkgolide A (GA), Ginkgolide B (GB), and Terpene Free Material (TFM)] could provide neuroprotection in ischemic conditions through heme oxygenase 1 (HO1). Mice were subjected to permanent distal middle cerebral artery occlusion (pMCAO) and survived for 7 days. HO1 knockout (HO1⁻/⁻) mice showed significantly higher (P<0.05) infarct volume and Neurologic Deficit Scores (NDS) as compared to their wildtype (WT) counterparts. In another cohort, WT mice subjected to pMCAO and treated at 4 h of pMCAO with 100 mg/kg EGb 761, 6 mg/kg BB, GA, GB, or 10 mg/kg TFM showed significantly lower (P<0.05) infarct volumes (BB; 29.0±3.9%, GA; 31.3±4.0%, GB; 32.0±3.8%, TFM; 32.5±3.5%, and EGb 761; 27.4±4.5%) than those in the vehicle-treated mice (46.0±3.7%). Similarly, NDS were lower in BB; 7.1±1.8, GA; 7.4±2.1, GB; 7.9±1.8, TFM; 7.7±1.7, and EGb 761; 6.8±2.0 groups as compared with the vehicle-treated group (13.8±1.5). Interestingly, the protective effect of EGb 761 was essentially lost when HO1 knockout mice were treated with EGb 761. In another cohort, HO1, vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) protein levels in the brain cortices appeared to be higher in EGb 761 and BB but not in GA, GB and TFM treated groups. Together, these results suggest that HO1 plays, at least in part, an important role in the neuroprotective mechanism of EGb 761 and in delayed ischemia. Targeting this pathway could lead to neuroprotective agents against ischemic stroke.

Mitochondrial damage-induced impairment of angiogenesis in the aging rat kidney

Decreased expression of vascular endothelial growth factor (VEGF) in the renal tubules is thought to cause progressive loss of the renal microvasculature with age. Mitochondrial dysfunction may be a principal phenomenon underlying the process of aging. The relation between VEGF expression and mitochondrial dysfunction in aging is not fully understood. We hypothesized that mitochondrial dysfunction blocks VEGF expression and contributes to impaired angiogenesis in the aging kidney. The aim of this study was to assess the role of mitochondria in VEGF expression in the aging rat kidney. We evaluated the accumulation of 8-hydroxy-2'-deoxyguanosine in mitochondrial DNA, as well as mitochondrial dysfunction, as assessed by electron microscopy of mitochondrial structure and histochemical staining for respiratory chain complex IV, in aging rat kidney. An increase in hypoxic area and a decrease in peritubular capillaries were detected in the cortex of aging rat kidneys; however, upregulation of VEGF expression was not observed. The expression of VEGF in proximal tubular epithelial cells in response to hypoxia was suppressed by the mitochondrial electron transfer inhibitor myxothiazol. Mitochondrial DNA-deficient cells also failed to upregulate VEGF expression under hypoxic conditions. These results indicate that impairment of VEGF upregulation, possibly as a result of mitochondrial dysfunction, contributes to impaired angiogenesis, which in turn leads to renal injury in the aging rat kidney.

Ginkgo biloba extract in the treatment of tinnitus: a systematic review

Tinnitus is a symptom frequently encountered by ear, nose, and throat practitioners. A causal treatment is rarely possible, and drug and nondrug treatment options are limited. One of the frequently prescribed treatments is Ginkgo biloba extract. Therefore, randomized, placebo-controlled clinical trials of Ginkgo biloba extract preparations were searched for and reviewed systematically. There is evidence of efficacy for the standardized extract, EGb 761(®) (Dr Willmar Schwabe GmbH & Co KG Pharmaceuticals, Karlsruhe, Germany), in the treatment of tinnitus from three trials in patients in whom tinnitus was the primary complaint. Supportive evidence comes from a further five trials in patients with age-associated cognitive impairment or dementia in whom tinnitus was present as a concomitant symptom. As yet, the efficacy of other ginkgo preparations has not been proven, which does not necessarily indicate ineffectiveness, but may be due to flawed clinical trials. In conclusion, EGb 761(®), a standardized Ginkgo biloba extract, is an evidence-based treatment option in tinnitus.

Brain mitochondrial dysfunction in aging, neurodegeneration, and Parkinson's disease

Brain senescence and neurodegeneration occur with a mitochondrial dysfunction characterized by impaired electron transfer and by oxidative damage. Brain mitochondria of old animals show decreased rates of electron transfer in complexes I and IV, decreased membrane potential, increased content of the oxidation products of phospholipids and proteins and increased size and fragility. This impairment, with complex I inactivation and oxidative damage, is named “complex I syndrome” and is recognized as characteristic of mammalian brain aging and of neurodegenerative diseases. Mitochondrial dysfunction is more marked in brain areas as rat hippocampus and frontal cortex, in human cortex in Parkinson's disease and dementia with Lewy bodies, and in substantia nigra in Parkinson's disease. The molecular mechanisms involved in complex I inactivation include the synergistic inactivations produced by ONOO− mediated reactions, by reactions with free radical intermediates of lipid peroxidation and by amine–aldehyde adduction reactions. The accumulation of oxidation products prompts the idea of antioxidant therapies. High doses of vitamin E produce a significant protection of complex I activity and mitochondrial function in rats and mice, and with improvement of neurological functions and increased median life span in mice. Mitochondria-targeted antioxidants, as the Skulachev cations covalently attached to vitamin E, ubiquinone and PBN and the SS tetrapeptides, are negatively charged and accumulate in mitochondria where they exert their antioxidant effects. Activation of the cellular mechanisms that regulate mitochondrial biogenesis is another potential therapeutic strategy, since the process generates organelles devoid of oxidation products and with full enzymatic activity and capacity for ATP production.

Mitochondrial dysfunction: common final pathway in brain aging and Alzheimer's disease--therapeutic aspects

As a fully differentiated organ, our brain is very sensitive to cumulative oxidative damage of proteins, lipids, and DNA occurring during normal aging because of its high energy metabolism and the relative low activity of antioxidative defense mechanisms. As a major consequence, perturbations of energy metabolism including mitochondrial dysfunction, alterations of signaling mechanisms and of gene expression culminate in functional deficits. With the increasing average life span of humans, age-related cognitive disorders such as Alzheimer's disease (AD) are a major health concern in our society. Age-related mitochondrial dysfunction underlies most neurodegenerative diseases, where it is potentiated by disease-specific factors. AD is characterized by two major histopathological hallmarks, initially intracellular and with the progression of the disease extracellular accumulation of oligomeric and fibrillar beta-amyloid peptides and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein. In this review, we focus on findings in AD animal and cell models indicating that these histopathological alterations induce functional deficits of the respiratory chain complexes and therefore consecutively result in mitochondrial dysfunction and oxidative stress. These parameters lead synergistically with the alterations of the brain aging process to typical signs of neurodegeneration in the later state of the disease, including synaptic dysfunction, loss of synapses and neurites, and finally neuronal loss. We suggest that mitochondrial protection and subsequent reduction of oxidative stress are important targets for prevention and long-term treatment of early stages of AD.

The mtDNA mutator mouse: Dissecting mitochondrial involvement in aging

The role of mtDNA mutations in aging has been intensely debated because of their low abundance and correlative connection with aging. The creation of mtDNA mutator mice provided the first evidence that somatic mtDNA mutations have the capacity to cause a variety of aging phenotypes in mammals, and they do so without inducing ROS production or increasing oxidative stress. We have recently provided evidence that the accumulation of point mutations in mtDNA leads to the synthesis of respiratory chain subunits with amino acid substitutions that impair complex stability in mtDNA mutator mice. Furthermore, we have demonstrated that the point mutations cause progressive respiratory chain deficiency, which, we propose, leads to premature aging. These results have been challenged by another group working on a similar model, who argues that the point mutations in mtDNA we found at very high levels in mtDNA mutator mice do not cause the phenotype. Instead, they argue that circular mtDNA molecules with large deletions, are the culprit. This intense debate about molecular mechanism of mitochondrial dysfunction that is causing progeroid phenotypes in the mtDNA mutator mice is the main topic of this research perspective.