23 research outputs found
Bioanalytical method validation and application to a phase 1, double-blind, randomized pharmacokinetic trial of a standardized Centella asiatica (L.) Urban water extract product in healthy older adults
Introduction:Centella asiatica is an herbaceous plant reputed in Eastern medicine to improve memory. Preclinical studies have shown that C. asiatica aqueous extract (CAW) improves neuronal health, reduces oxidative stress, and positively impacts learning and cognition. This study aimed to develop and validate bioanalytical methods for detecting known bioactive compounds from C. asiatica in human biological matrices and apply them to a human pharmacokinetic trial in healthy older adults.Methods: High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used for detecting triterpenes and caffeoylquinic acids from C. asiatica, or their metabolites, in human plasma and urine. Validation parameters including linearity, precision, accuracy, recovery and thermal stability were evaluated. The method was applied to a Phase I, randomized, double-blind, crossover trial of two doses (2 or 4 g) of a standardized C. asiatica water extract product (CAP) in eight healthy older adults. Pharmacokinetic parameters were measured over a 12-h post administration period and acute safety was assessed.Results: The method satisfied US Food & Drug Administration criteria for linearity and recovery of the analytes of interest in human plasma and urine. The method also satisfied criteria for precision and accuracy at medium and high concentrations. Single administration of 2 and 4 g of CAP was well tolerated and safe in healthy older adults. The parent triterpene glycosides, asiaticoside and madecassoside, were not detected in plasma and in minimal amounts in urinary excretion analyses, while the aglycones, asiatic acid and madecassic acid, showed readily detectable pharmacokinetic profiles. Similarly, the di-caffeoylquinic acids and mono-caffeoylquinic acids were detected in low quantities, while their putative metabolites showed readily detectable pharmacokinetic profiles and urinary excretion.Discussion: This method was able to identify and calculate the concentration of triterpenes and caffeoylquinic acids from C. asiatica, or their metabolites, in human plasma and urine. The oral absorption of these key compounds from CAP, and its acute safety in healthy older adults, support the use of this C. asiatica product in future clinical trials
Loss of NRF2 results in decreased neuronal arborization and synaptic density and causes exacerbated age-related cognitive impairment.
Background: As the brain ages, free radicals accumulate and cause damage to cellular macromolecules. This increased oxidative damage is thought to contribute to the cognitive decline observed in aging. Activation of the antioxidant regulatory transcription factor NRF2 (Nuclear factor erythroid-derived 2) has been shown to improve neuronal health in aging and neurodegenerative diseases. Yet exactly how NRF2 participates in maintaining synaptic and cognitive function has not been fully elucidated. This study investigates how loss of NRF2 affects synaptic density and cognitive performance in aged mice.
Methods: Dendritic arborization and synaptic was evaluated in hippocampal neurons isolated from mice lacking NRF2 (NRF2KO) and from wild-type (WT) C57BL6 mice. Mitochondrial function of these neurons was evaluated using the Seahorse XF platform. Hippocampal and cortical expression of synaptic genes were measured.
Results: NRF2KO neurons had significantly reduced dendritic complexity relative to WT neurons as well as reduced synaptic gene expression. Similar deficits in synaptic gene expression were observed in the brains of aged NRF2KO mice relative to WT mice.
Conclusions: These data point to a role for NRF2 in maintaining synaptic health and cognitive function during aging and suggest that the transcription factor may be a viable target for cognitive enhancing interventions. Because increased oxidative stress and cognitive impairment also occur together in many neurodegenerative conditions the therapeutic potential of NRF2 activating agents may extend beyond healthy aging
Centella asiatica Attenuates Mitochondrial Dysfunction and Oxidative Stress in Aβ-Exposed Hippocampal Neurons
Centella asiatica has been used for centuries to enhance memory. We have previously shown that a water extract of Centella asiatica (CAW) protects against the deleterious effects of amyloid-β (Aβ) in neuroblastoma cells and attenuates Aβ-induced cognitive deficits in mice. Yet, the neuroprotective mechanism of CAW has yet to be thoroughly explored in neurons from these animals. This study investigates the effects of CAW on neuronal metabolism and oxidative stress in isolated Aβ-expressing neurons. Hippocampal neurons from amyloid precursor protein overexpressing Tg2576 mice and wild-type (WT) littermates were treated with CAW. In both genotypes, CAW increased the expression of antioxidant response genes which attenuated the Aβ-induced elevations in reactive oxygen species (ROS) and lipid peroxidation in Tg2576 neurons. CAW also improved mitochondrial function in both genotypes and increased the expression of electron transport chain enzymes and mitochondrial labeling, suggesting an increase in mitochondrial content. These data show that CAW protects against mitochondrial dysfunction and oxidative stress in Aβ-exposed hippocampal neurons which could contribute to the beneficial effects of the extract observed in vivo. Since CAW also improved mitochondrial function in the absence of Aβ, these results suggest a broader utility for other conditions where neuronal mitochondrial dysfunction occurs
Centella asiatica Extract Improves Behavioral Deficits in a Mouse Model of Alzheimer's Disease: Investigation of a Possible Mechanism of Action
Centella asiatica (CA), commonly named gotu kola, is an Ayurvedic herb used to enhance memory and nerve function. To investigate the potential use of CA in Alzheimer's disease (AD), we examined the effects of a water extract of CA (GKW) in the Tg2576 mouse, a murine model of AD with high β-amyloid burden. Orally administered GKW attenuated β-amyloid-associated behavioral abnormalities in these mice. In vitro, GKW protected SH-SY5Y cells and MC65 human neuroblastoma cells from toxicity induced by exogenously added and endogenously generated β-amyloid, respectively. GKW prevented intracellular β-amyloid aggregate formation in MC65 cells. GKW did not show anticholinesterase activity or protect neurons from oxidative damage and glutamate toxicity, mechanisms of current AD therapies. GKW is rich in phenolic compounds and does not contain asiatic acid, a known CA neuroprotective triterpene. CA thus offers a unique therapeutic mechanism and novel active compounds of potential relevance to the treatment of AD
Curcumin Treatment Improves Motor Behavior in α-Synuclein Transgenic Mice
<div><p>The curry spice curcumin plays a protective role in mouse models of neurodegenerative diseases, and can also directly modulate aggregation of α-synuclein protein <i>in vitro</i>, yet no studies have described the interaction of curcumin and α-synuclein in genetic synucleinopathy mouse models. Here we examined the effect of chronic and acute curcumin treatment in the Syn-GFP mouse line, which overexpresses wild-type human α-synuclein protein. We discovered that curcumin diet intervention significantly improved gait impairments and resulted in an increase in phosphorylated forms of α-synuclein at cortical presynaptic terminals. Acute curcumin treatment also caused an increase in phosphorylated α-synuclein in terminals, but had no direct effect on α-synuclein aggregation, as measured by <i>in vivo</i> multiphoton imaging and Proteinase-K digestion. Using LC-MS/MS, we detected ~5 ng/mL and ~12 ng/mL free curcumin in the plasma of chronic or acutely treated mice, with a glucuronidation rate of 94% and 97%, respectively. Despite the low plasma levels and extensive metabolism of curcumin, these results show that dietary curcumin intervention correlates with significant behavioral and molecular changes in a genetic synucleinopathy mouse model that mimics human disease.</p></div
LC-MS/MS detection of curcumin in plasma from mice on a curcumin diet.
<p>Food consumption (A) and body weight (B) for mice on a 500 ppm curcumin diet or control diet, recorded weekly for 6 months. Extracted-ion chromatogram for plasma matrix spiked with 100 ng/mL curcumin (C), showing distinct peaks for curcumin and honokiol internal standards.</p
No change in in vivo FRAP kinetics in acutely treated curcumin mice.
<p>(A) Photobleaching and recovery imaging of presynaptic Syn-GFP protein in cortical brain tissue, through a cranial window in the skull. (B) FRAP recovery curves from DMSO and curcumin (C) treated animals, at pre-treatment, 1 week, and 2 week time points. (D) Immobile Fraction and recovery time constant tau values (E) do not change over time or with treatment (n = 3 animals curcumin, n = 2 animals DMSO, 2–5 regions per animal per time point; yellow box indicates bleach ROI; Scale bar = 10 μm).</p
Curcumin diet mice show improved gait.
<p>Syn-GFP mice on a 6 month curcumin diet intervention had significant changes in gait compare to control diet mice, including increased fore paw swing duration (A), decreased fore paw ataxia coefficient (B), decreased for paw stride length variability (C), and decreased fore paw stance width variability (D). The ataxia coefficient, and variability in stride length and stance width, are all associated with a PD-like phenotype in both humans and mice (flat platform run, n = 4 animals per group, *p<0.05, **p<0.01).</p