The effect of ginkgo biloba extract on free radical production in hypoxic rats

Investigating the Impacts of Diet, Supplementation, Microbiota, Gut-Brain Axis on Schizophrenia: A Narrative Review

Schizophrenia is a disease with a complex etiology that significantly impairs the functioning of patients. In recent years, there has been increasing focus on the importance of the gut microbiota in the context of the gut-brain axis. In our study, we analyzed data on the gut-brain axis in relation to schizophrenia, as well as the impacts of eating habits, the use of various supplements, and diets on schizophrenia. Additionally, the study investigated the impact of antipsychotics on the development of metabolic disorders, such as diabetes, dyslipidemia, and obesity. There may be significant clinical benefits to be gained from therapies supported by supplements such as omega-3 fatty acids, B vitamins, and probiotics. The results suggest the need for a holistic approach to the treatment of schizophrenia, incorporating both drug therapy and dietary interventions.

Ginkgo biloba extract mitigates the neurotoxicity of AlCl3 in alzheimer rat's model: role of apolipoprotein E4 and clusterin genes in stimulating ROS generation and apoptosis

PURPOSE

Alzheimer's disease (AD) appears as a result of an increase in the accumulation of amyloid beta peptide (Aβ) and a decrease in neurotransmitters (acetylcholine) within the brain cells which may be due to increase in acetylcholinesterase (AchE) activity and change in expression of Apolipoprotein E4 (ApoE4) and Clusterin (Clu) genes. The aim of the present study was using natural products such as Ginkgo biloba (G. biloba) extract that has the potential to reduce Aβ formation and increase AchE inhibition with its ability to save neuronal DNA from damage.

METHODS

Sixty male aged rats were divided into six experimental groups exposed to AlCl3 to induce AD model and were treated with G. biloba extract. Collected brain tissues were used to assess the apoptosis rate, reactive oxygen species (ROS) generation, AchE inhibitory activity, expression alteration in ApoE4 and Clu genes, DNA fragmentations and gutathione peroxidase (GPx) activity.Results: The results exhibited that rats exposed to AlCl3 increased significantly rate of apoptosis, ROS formation, DNA fragmentation, up-regulation of ApoE4 and Clu genes as well as decrease of AchE inhibitory activity and GPx activity compared with those in control rats. However, treatment of AlCl3-rats with G. biloba extract improved the above neurotoxicity results induced by AlCl3 exposure.

CONCLUSIONS

It is therefore likely that G. biloba extract's protective properties against AD are due to its ability to activate the response against oxidative stress.

Ginkgo biloba Administered Singly and Combined With Antioxidants in Tinnitus Patients

BACKGROUND AND OBJECTIVES

Tinnitus, or ear ringing, involves impulsive and spontaneous activity in the auditory neurons. Its prevalence is high in the elderly, but 10%-15% of adults suffer from tinnitus, affecting their quality of life. Therefore, this study aimed to evaluate the efficacy of Ginkgo biloba administered singly and in combination with antioxidants in tinnitus patients. Subjects and.

METHODS

Patients were randomly allocated to Placebo (T0, n=22), Treatment 1 (T1, n=24), and Treatment 2 (T2, n=23) groups. The patients were educated on the study's methodology and were instructed to visit at 0, 4, 8, 12, and 14 weeks. The placebo group received starch capsule supplements. Conversely, the treatment groups received Ginkgo biloba (60 mg twice a day) singly and in combination with antioxidants. We enrolled 69 patients aged 40-70 years (41 men, 28 women). The Tinnitus Handicap Index (THI), Visual Analogue Score (VAS), and Short Form 36 (SF-36) Health Scores were determined pre- and post-treatment at each visit.

RESULTS

Supplementation of Ginkgo biloba, along with antioxidants, provided marked improvement (p<0.05) in post-treatment THI and VAS scores in the T2 group compared to those in the T1 and T0 groups. The greatest (p<0.05) percent difference was observed in the pre- and post-treatment THI (-36%) and VAS scores (-22.6%) of T2 patients. Likewise, the SF-36 scores improved significantly (p<0.05) in the T2 group in varied parameters.

CONCLUSIONS

Ginkgo biloba, along with antioxidants, can be a promising therapy for tinnitus patients, providing marked improvement in THI, VAS, and SF-36 scores.

Potentialities of Ginkgo extract on toxicants, toxins, and radiation: a critical review

Exposure to toxins is a severe threat to human health and life in today's developing and industrialized world. Therefore, identifying a protective chemical could be valuable and fascinating in this case. The purpose of this article was to bring together thorough review of studies on Ginkgo biloba to aid in the creation of ways for delivering its phytoconstituents to treat toxicants and radiation. This review gathered and evaluated studies on the defensive impact of Ginkgo biloba extract (GBE) against toxicities caused by toxic chemical agents (such as lead, cadmium, and aluminum), natural toxins (for example, lipopolysaccharide-induced toxicity and damage, gossypol, latadenes, and lotaustralin), and radiation (for example, gamma, ultra-violet, and radio-frequency radiation). According to this review, GBE has a considerable therapeutic effect by influencing specific pathophysiological targets. Furthermore, GBE has antioxidant, anti-inflammatory, anti-apoptotic, and antigenotoxicity properties against various toxicities. These are due to flavone glycosides (primarily isorhamnetin, kaempferol, and quercetin) and terpene trilactones (ginkgolides A, B, C, and bilobalide) that aid GBEs' neutralizing effect against radiation and toxins by acting independently or synergistically. This will serve as a reference for the functional food, cosmetic, and pharmaceutical industries worldwide.

Hypobaric hypoxia induced fear and extinction memory impairment and effect of Ginkgo biloba in its amelioration: Behavioral, neurochemical and molecular correlates

Regulated fear and extinction memory is essential for balanced behavioral response. Limbic brain regions are susceptible to hypobaric hypoxia (HH) and are putative target for fear extinction deficit and dysregulation. The present study aimed to examine the effect of HH and Ginkgo biloba extract (GBE) on fear and extinction memory with the underlying mechanism. Adult male Sprague-Dawley rats were evaluated for fear extinction and anxious behavior following GBE administration during HH exposure. Blood and tissue (PFC, hippocampus and amygdala) samples were collected for biochemical, morphological and molecular studies. Results revealed deficit in contextual and cued fear extinction following 3 days of HH exposure. Increased corticosterone, glutamate with decreased GABA level was found with marked pyknosis, decrease in apical dendritic length and number of functional spines. Decline in mRNA expression level of synaptic plasticity genes and immunoreactivity of BDNF, synaptophysin, PSD95, spinophilin was observed following HH exposure. GBE administration during HH exposure improved fear and extinction memory along with decline in anxious behavior. It restored corticosterone, glutamate and GABA levels with an increase in apical dendritic length and number of functional spines with a reduction in pyknosis. It also improved mRNA expression level and immunoreactivity of neurotrophic and synaptic proteins. The present study is the first which demonstrates fear extinction deficit and anxious behavior following HH exposure. GBE administration ameliorated fear and extinction memory dysregulation by restoration of neurotransmitter levels, neuronal pyknosis and synaptic connections along with improved neurotrophic and synaptic protein expressions.

Neuroprotective and Antioxidant Effect of Ginkgo biloba Extract Against AD and Other Neurological Disorders

Alzheimer's disease (AD) is the most common progressive human neurodegenerative disorder affecting elderly population worldwide. Hence, prevention of AD has been a priority of AD research worldwide. Based on understanding of disease mechanism, different therapeutic strategies involving synthetic and herbal approaches are being used against AD. Among the herbal extract, Ginkgo biloba extract (GBE) is one of the most investigated herbal remedy for cognitive disorders and Alzheimer's disease (AD). Standardized extract of Ginkgo biloba is a popular dietary supplement taken by the elderly population to improve memory and age-related loss of cognitive function. Nevertheless, its efficacy in the prevention and treatment of dementia remains controversial. Specifically, the added effects of GBE in subjects already receiving "conventional" anti-dementia treatments have been to date very scarcely investigated. This review summarizes recent advancements in our understanding of the potential use of Ginkgo biloba extract in the prevention of AD including its antioxidant property. A better understanding of the mechanisms of action of GBE against AD will be important for designing therapeutic strategies, for basic understanding of the underlying neurodegenerative processes, and for a better understanding of the effectiveness and complexity of this herbal medicine.

Ginkgo biloba extract for prevention of acute mountain sickness: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

Trials of ginkgo biloba extract (GBE) for the prevention of acute mountain sickness (AMS) have been published since 1996. Because of their conflicting results, the efficacy of GBE remains unclear. We performed a systematic review and meta-analysis to assess whether GBE prevents AMS.

METHODS

The Cochrane Library, EMBASE, Google Scholar and PubMed databases were searched for articles published up to 20 May 2017. Only randomised controlled trials were included. AMS was defined as an Environmental Symptom Questionnaire Acute Mountain Sickness-Cerebral score ≥0.7 or Lake Louise Score ≥3 with headache. The main outcome measure was the relative risk (RR) of AMS in participants receiving GBE for prophylaxis. Meta-analyses were conducted using random-effects models. Sensitivity analyses, subgroup analyses and tests for publication bias were conducted.

RESULTS

Seven study groups in six published articles met all eligibility criteria, including the article published by Leadbetter et al, where two randomised controlled trials were conducted. Overall, 451 participants were enrolled. In the primary meta-analysis of all seven study groups, GBE showed trend of AMS prophylaxis, but it is not statistically significant (RR=0.68; 95% CI 0.45 to 1.04; p=0.08). The I² statistic was 58.7% (p=0.02), indicating substantial heterogeneity. The pooled risk difference (RD) revealed a significant risk reduction in participants who use GBE (RD=-25%; 95% CI, from a reduction of 45% to 6%; p=0.011) The results of subgroup analyses of studies with low risk of bias, low starting altitude (<2500 m), number of treatment days before ascending and dosage of GBE are not statistically significant.

CONCLUSION

The currently available data suggest that although GBE may tend towards AMS prophylaxis, there are not enough data to show the statistically significant effect of GBE on preventing AMS. Further large randomised controlled studies are warranted.

Anti-inflammatory effects of Ginkgo biloba extract against trimethyltin-induced hippocampal neuronal injury

BACKGROUND

Despite the immense neuromodulatory potentials of Ginkgo biloba extract as a memory enhancer, its underlying mechanism seems inadequate particularly with regard to its anti-inflammatory properties.

AIM

The objective of the present study is to investigate the protective potentials of Ginkgo biloba extract (GBE) against hippocampal neuronal injury induced by trimethyltin (TMT), a potent neurotoxicant.

METHODS

Male SD rats were administered trimethyltin (8.5 mg kg^-1 b.wt) single intraperitoneal (i.p.) injection, followed by Ginkgo biloba extract (100 mg kg^-1 b.wt i.p) for 21 days.

RESULTS

The co-administration of GBE with TMT showed marked improvement in cognitive functions. Concomitantly, there was a significant decrease in oxidative stress as evident by reduction in MDA and total ROS levels. In addition, there was a marked suppression of astrocyte activation (GFAP), transcription factor NFκB and proinflammatory cytokines (TNF-α, IL-1α, 1L-6), which were found to be elevated by TMT administration. Histopathological observations showed remarkable improvement in hippocampal neuronal injury in the conjunctive group.

CONCLUSION

Therefore, it is suggested that Ginkgo biloba extract is an effective agent against trimethyltin-induced hippocampal neuronal loss owing to its antioxidative as well as anti-inflammatory properties.

Enhanced dissolution rate and oral bioavailability of ginkgo biloba extract by preparing nanoparticles via emulsion solvent evaporation combined with freeze drying (ESE-FR)

Dissolution rate and oral bioavailability of GBE nanoparticles were significantly improved by emulsion solvent evaporation combined with freeze drying (ESE-FR), implying that ESE-FR has great potential value in the preparation of oral GBE drugs.

Potent α-glucosidase inhibitors isolated from Ginkgo biloba leaves

In vitro α-glucosidase inhibitory activity of Ginkgo biloba leaves was investigated. The inhibitory activity of methanol extracts from yellow and green leaves was 13.8 and 40.1 μg mL(-1), respectively. Each methanol extract was separated into its respective fraction by solvent-solvent extraction with n-hexane, chloroform, ethyl acetate and n-butanol. The n-hexane fractions (in both methanol extracts from green and yellow leaves) exhibited high α-glucosidase inhibitory activity with IC50 values of 13.6 and 13.4 μg mL(-1), respectively. Further fractionation of the n-hexane fractions by silica gel column chromatography gave the most active fraction which was identified as ginkgolic acid (C13:0) and a mixture (C13:0, C15:0, C15: 1, C17:1 and C17:2). Ginkgolic acid (C13:0) exhibited the highest α-glucosidase inhibitory activity. This is the first study to successfully isolate ginkgolic acids as α-glucosidase inhibitors.

Antihyperglycemic effect of Ginkgo biloba extract in streptozotocin-induced diabetes in rats

The Ginkgo biloba extract (GBE) has been reported to have a wide range of health benefits in traditional Chinese medicine. The aim of this study was to evaluate the antihyperglycemic effects of GBE on streptozotocin- (STZ-) induced diabetes in rats. Diabetes was induced in male Wistar rats by the administration of STZ (60 mg/kg b.w.) intraperitoneally. GBE (100, 200, and 300 mg/kg b.w.) was administered orally once a day for a period of 30 days. Body weight and blood glucose levels were determined in different experimental days. Serum lipid profile and antioxidant enzymes in hepatic and pancreatic tissue were measured at the end of the experimental period. Significant decreases in body weight and antioxidant ability and increases in blood glucose, lipid profile, and lipid peroxidation were observed in STZ-induced diabetic rats. The administration of GBE and glibenclamide daily for 30 days in STZ-induced diabetic rats reversed the above parameters significantly. GBE possesses antihyperglycemic, antioxidant, and antihyperlipidemia activities in STZ-induced chronic diabetic rats, which promisingly support the use of GBE as a food supplement or an adjunct treatment for diabetics.

Effects of bilobalide on anxiety, spatial learning, memory and levels of hippocampal glucocorticoid receptors in male Kunming mice

With various constituents in ginkgo biloba extract, the detailed internal mechanism underlying a reduction in anxiety and improvements to learning and memory from GBE is not well understood. The present study investigated whether bilobalide, an important constituent in GBE, could affect anxiety, spatial learning and memory in male mice and whether hippocampal glucocorticoid receptor expression is associated with alteration in these behaviors. Mice were treated orally either with sesame seed oil or one of three dosages of bilobalide (2.5, 5.0 and 10.0 mg/kg) daily until testing. A series of behavioral tests showed that repeated bilobalide treatment decreased levels of anxiety-like behavior and increased locomotor activity in open field and elevated plus maze tests. Treatment with bilobalide also shortened the time taken to find the platform in a Morris water-maze test. Mice exposed to bilobalide showed higher and dose-dependent levels of glucocorticoid receptor expression in the hippocampus. These results suggest that bilobalide reduces anxiety levels and enhances spatial learning and memory, possibly through an increase in hippocampal glucocorticoid receptor expression. This finding sheds light on the mechanisms underlying the effect of ginkgo biloba extract on behavior and also provides an important candidate drug in treatment of anxiety, depression, hypomnesia and amnesia.

Ginkgo biloba protects against intermittent hypoxia-induced memory deficits and hippocampal DNA damage in rats

The aim of the present study was to explore the potential protective effect of Ginkgo biloba extract (EGb 761) on intermittent hypoxia (IH)-induced memory deficits and oxidative stress in rats.

METHODS

The passive avoidance reflex (PAR) test was employed to assess the effect of concurrent EGb 761 treatment in different dose levels on the memory deficits that were induced by concurrent long-term exposure to IH (21 days). The levels of hippocampal malondialdehyde (MDA), nitric oxide (NO), and intracellular glutathione (GSH) and the activity of glutathione peroxidase (GSH-Px) were estimated. In addition, serum and hippocampal 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were assessed to study the effect of EGb 761 on hippocampal oxidative DNA damage induced by IH.

RESULTS

Exposure to long-term IH in rats induced marked memory impairment that was indicated by a significant decrease in the retention latency in the PAR test. This effect was accompanied by a significant increase in hippocampal oxidative stress and DNA damage. EGb 761 that was administered in either 50- or 100-mg/kg doses per day reversed IH-induced memory deficits, an effect that was accompanied by a significant decrease in hippocampal MDA and NO levels. The antioxidant defence (GSH and GSH-Px) that was depressed by IH was significantly reactivated by EGb 761. Furthermore, serum and hippocampal levels of 8-OHdG that were elevated by IH were significantly reduced.

CONCLUSIONS

EGb 761 can protect against IH-induced memory impairment, oxidative stress and neuronal DNA damage, possibly through multiple mechanisms involving its potential anti-oxidative effect.

Protective effects of Ginkgo biloba extract in rats with hypoxia/reoxygenation-induced intestinal injury

BACKGROUND

The purpose of this study is to investigate the protective effects of Ginkgo biloba extract (EGb 761) in rat pups with hypoxia/reoxygenation (H/R)-induced bowel injury.

METHODS

One-day-old Wistar albino rat pups (n = 21) were randomly divided into 3 groups: group 1 (control, untreated and not exposed to H/R, n = 7), group 2 (untreated but exposed to H/R, n = 7), and group 3 (EGb 761 + H/R, n = 7). Ginkgo biloba extract was administered (100 mg/kg per day, subcutaneously) to group 3 for 3 days. On the fourth day, all animals except controls were exposed to H/R and were killed 6 hours after H/R. Histopathologic injury scores (HIS), malondialdehyde, glutathione (GSH), GSH-peroxidase (Px) activities, and nitric oxide (NO) levels were measured on intestinal samples.

RESULTS

Although the control group had normal HIS, group 2 had grade 3 HIS. In contrast, group 3 had minimal HIS, and these results were significantly better than those of group 2 (P < .001). Malondialdehyde and NO levels of group 3 were significantly lower than those of group 2 (P < .01). Glutathione and GSH-Px activities of group 1 were higher than those of groups 2 and 3 (P < .05). However, there were no significant differences for GSH and GSH-Px activities between groups 2 and 3.

CONCLUSIONS

This study showed that hypoxia and NO contributed to the pathogenesis of H/R-induced intestinal injury and that prophylactically administered EGb 761 had a protective effect on bowel injury.

Therapeutic applications of compounds in the Magnolia family

The bark and/or seed cones of the Magnolia tree have been used in traditional herbal medicines in Korea, China and Japan. Bioactive ingredients such as magnolol, honokiol, 4-O-methylhonokiol and obovatol have received great attention, judging by the large number of investigators who have studied their pharmacological effects for the treatment of various diseases. Recently, many investigators reported the anti-cancer, anti-stress, anti-anxiety, anti-depressant, anti-oxidant, anti-inflammatory and hepatoprotective effects as well as toxicities and pharmacokinetics data, however, the mechanisms underlying these pharmacological activities are not clear. The aim of this study was to review a variety of experimental and clinical reports and, describe the effectiveness, toxicities and pharmacokinetics, and possible mechanisms of Magnolia and/or its constituents.

Terpene trilactones from Gingko biloba: from ancient times to the 21st century

Ginkgolides were always close to my heart. I continue to be strongly attracted to Ginkgo biloba, the ginkgolides and bilobalide. Starting in 1963, I became fascinated by these molecules while working on their isolation and structure elucidation in Sendai. Presumably, due to the ginkgolide studies, I received an invitation to join the faculty at Columbia University. After almost three decades of not touching the ginkgolide project, we have unexpectedly resumed the studies, at this time because of their enigmatic biological effects. This account is a reflection on earlier studies, as well as an outline of our current work.

Ginkgo biloba extract prevents high altitude pulmonary edema in rats

Ginkgo biloba reduces the severity of acute mountain sickness in humans, but protection against high altitude pulmonary edema (HAPE) has not been reported. This study was conducted to determine if G. biloba would prevent early HAPE in rats. Six rats (ginkgo group) received G. biloba (200 mg/kg body weight in drinking water and an equal amount in peanut butter) for 2 days before and during high altitude exposure (380 mmHg pressure for 24 h). Six other rats (control group) received water and peanut butter alone. Protein concentrations in bronchoalveolar lavage fluid (BALF) were increased in control rats (19.8 +/- 2.6 mg/dL) compared to ginkgo rats (11.6 +/- 0.9 mg/dL; p = 0.014), demonstrating that untreated (control) rats developed mild HAPE following high altitude exposure. For comparison, BALF protein concentrations in sea-level rats (air group) given peanut butter were 12.6 +/- 0.8 mg/dL (n = 6). Although pleural effusions did not develop in any rats, the protein concentrations of pleural fluid were also increased in control rats (4.9 +/- 0.16 g/dL) compared to ginkgo rats (4.0 +/- 0.13; p = 0.001); air group: 3.5 +/- 0.08 g/dL. There were no differences in wet/dry lung weight ratios between groups, but wet left lung weights/preexposure body weight were increased in control rats (1.26 +/- 0.02 g/kg) compared to the ginkgo group (1.17 +/- 0.01 g/kg; p = 0.002); air group: 1.11 +/- 0.03 g/kg. In conclusion, the data show that G. biloba prevents the development of early HAPE in rats.

Functional foods, herbs and nutraceuticals: towards biochemical mechanisms of healthy aging

Aging is associated with mitochondrial dysfunctions, which trigger membrane leakage, release of reactive species from oxygen and nitrogen and subsequent induction of peroxidative reactions that result in biomolecules' damaging and releasing of metals with amplification of free radicals discharge. Free radicals induce neuronal cell death increasing tissue loss, which could be associated with memory detriment. These pathological events are involved in cardiovascular, neurodegenerative and carcinogenic processes. Dietary bioactive compounds from different functional foods, herbs and nutraceuticals (ginseng, ginkgo, nuts, grains, tomato, soy phytoestrogens, curcumin, melatonin, polyphenols, antioxidant vitamins, carnitine, carnosine, ubiquinone, etc.) can ameliorate or even prevent diseases. Protection from chronic diseases of aging involves antioxidant activities, mitochondrial stabilizing functions, metal chelating activities, inhibition of apoptosis of vital cells, and induction of cancer cell apoptosis. Functional foods and nutraceuticals constitute a great promise to improve health and prevent aging-related chronic diseases.

Ototoxicidade da cisplatina e otoproteção pelo extrato de ginkgo biloba às células ciliadas externas: estudo anatômico e eletrofisiológico

A Cisplatina é uma potente droga antineoplásica, largamente utilizada para o tratamento do câncer, tanto em adultos quanto em crianças. Dentre seus efeitos colaterais, a ototoxicidade se apresenta como um dos mais importantes e leva à perda auditiva irreversível, bilateral, para as altas freqüências (4KHz#8KHz). Estudos têm tentado identificar drogas que, associadas à cisplatina possam atuar como otoprotetores. Sabe-se que o mecanismo da ototoxicidade pela cisplatina está relacionado a alterações nos mecanismos antioxidantes das células ciliadas, principalmente as células ciliadas externas da cóclea. OBJETIVO: Nossa proposta foi de avaliar através de emissões otoacústicas, por produtos de distorção (EOAPD) e por microscopia eletrônica de superfície (ME), a ação do extrato de ginkgo biloba (EGB 761), que tem conhecida ação antioxidante, como possível otoprotetor, utilizando como modelo experimental cobaias albinas. FORMA DE ESTUDO: Experimental. MATERIAL E MÉTODO: Observamos EOAPD presentes pré e pós tratamento no grupo EGB (100 mg/Kg/dia via oral) e 90 minutos após cisplatina (80 mg/Kg/dia via intraperitoneal) por 8 dias. RESULTADO: Houve também manutenção da arquitetura ciliar nas células ciliadas externas em todas as espiras da cóclea, enquanto que no grupo tratado somente com cisplatina (80 mg/Kg/dia via intraperitoneal) por 8 dias, houve desaparecimento das EOAPD pós tratamento, com desaparecimento dos cilios das células ciliadas externas e distorção na arquitetura dos cílios remanescentes à ME. CONCLUSÃO: Concluímos que a EGB, por sua ação antioxidante, atua como fator otoprotetor à ototoxicidade pela cisplatina, devendo ser testada tal ação na prática clínica em pacientes que utilizam a cisplatina, pois o uso do EGB está extremamente difundido no tratamento de diferentes doenças.

Antioxidant nutrients and hypoxia/ischemia brain injury in rodents

Cerebral ischemia and recirculation cause delayed neuronal death in rodents, such as Mongolian gerbils and stroke-prone spontaneously hypertensive rats (SHRSP), which were used as an experimental stroke model. It was documented that an enhanced nitric oxide production, the occurrence of apoptosis, and an attenuated redox regulatory system contribute to the development of delayed neuronal death. Many studies have suggested the beneficial antioxidant effects of antioxidant nutrients such as vitamin E, green tea extract, ginkgo biloba extract, resveratrol and niacin in cerebral ischemia and recirculation brain injury. These results are important in light of an attenuation of the deleterious consequences of oxidative stress in ischemia and recirculation injury.

Efficient extraction of ginkgolides and bilobalide from Ginkgo biloba leaves

An efficient and rapid protocol has been developed for extracting ginkgolides and bilobalide (terpene trilactones) from Ginkgo biloba leaves. The procedure takes advantage of the extraordinary stability of the terpene trilactone structure to a variety of chemical treatments, especially oxidation, despite the presence of multiple oxygen functions. The protocol involves boiling the aqueous extract of leaves with dilute hydrogen peroxide, extraction with ethyl acetate, washing with basic solutions, and charcoal filtration to yield an off-white powder, terpene trilactone content 60-70%. It is likely that the hydrogen peroxide treatment degrades the undesired leaf constituents that lead to intense emulsification during extractions. Further reversed-phase chromatography of the extracts with polymeric resins removes the undesirable ginkgolic acids to amounts less than 10 ppm. The extracts are suited for pure terpene trilactone preparation, enrichment of terpene trilactone content in nutraceuticals, and preparations of low-flavonoid/high-terpene trilactone controls in medicinal studies. The four ginkgolides (ginkgolides A, B, C, J) and bilobalide isolated from the extract were identical in all respects with authentic specimens.