New insights into huperzine A for the treatment of Alzheimer's disease

Synthesis and biological evaluation of novel pyrrolo[2,3-b]pyridine derivatives as potent GSK-3β inhibitors for treating Alzheimer's disease

The development of potent glycogen synthase kinase-3β (GSK-3β) inhibitor has been increasingly recognized as the candidate treatment against the multifactorial pathogenic mechanism of Alzheimer's disease (AD). This study prepared various new pyrrolo[2,3-b]pyridine derivatives, evaluated the anti-AD activities and detected the security based on the structure-guided rational design. Our results indicated that many pyrrolo[2,3-b]pyridine derivatives had strong GSK-3β inhibitory activities, particularly compounds 41, 46 and 54, with the half maximal inhibitory concentrations (IC50) of 0.22, 0.26 and 0.24 nM, respectively, and each of them generally possessed GSK-3β selectivity over 24 structurally similar kinases. In addition, further targeting studies at the cellular level revealed that compound 41 increased GSK-3β phosphorylation at Ser9 site dose-dependently for inhibiting GSK-3β activity, therefore inhibiting the hyperphosphorylation of tau protein by decreasing the p-tau-Ser396 abundance. Moreover, 41 up-regulated β-catenin and neurogenesis-related markers (GAP43 and MAP-2), thereby promoting neurite outgrowth of neurons in SH-SY5Y cells. According to the in vitro cells assay, 41 showed the lower cytotoxicity to SH-SY5Y cells with a survival rate of over 70 % at the concentration of 100 μM. In vivo efficacy and acute toxicity experiments showed that, 41 effectively ameliorated the dyskinesia in AlCl3-induced zebrafish AD models and exhibited its low-toxicity nature in C57BL/6 mice. Overall, the pyrrolo[2,3-b]pyridine derivative 41 could serve as a promising GSK-3β inhibitor for treating AD.

Multi-target directed ligands inspired natural products as an effective approach for the treatment of complex chronic health disorders

Complex diseases involve multifaceted etiological components, which limit the effectiveness of conventional targeted therapies. Therefore, standard medicinal treatments often face significant challenges and failures when addressing these disease conditions. Furthermore, the growing interest in multidrug resistance (MDR), the occurrence of adverse drug reactions related to use traditional approaches, and the limited clinical efficacy of single-target drug therapy have increased the demand for innovative drug treatments. In this rapidly evolving era, the exploration of multi-target directed ligands (MTDLs) derived from natural products has granted us access to a wide range of compounds with medicinal properties. The allure of these MTDLs lies in their unique ability to minimize side effects from using two medicinal agents, establishing them as the preferred choice for drug developers. MTDLs have been recognized for their extraordinary capacity to collectively hinder multiple pathways implicated in the development of intricate diseases by merging or linking active molecules obtained from these sources. This review delves into promising MTDLs derived from natural products, which modulates diverse biological pathways implicated in complex diseased conditions particularly Alzheimer's disease, diabetes, cardiac disorders and inflammatory conditions.

Unraveling the Nexus: The Role of Collapsin Response Mediator Protein 2 Phosphorylation in Neurodegeneration and Neuroregeneration

Neurodegenerative disease characterized by the progressive damage of the nervous system, and neuropathies caused by the neuronal injury are both led to substantial impairments in neural function and quality of life among geriatric populations. Recovery from nerve damage and neurodegenerative diseases present a significant challenge, as the central nervous system (CNS) has limited capacity for self-repair. Investigating mechanism of neurodegeneration and regeneration is essential for advancing our understanding and development of effective therapies for nerve damage and degenerative conditions, which can significantly enhance patient outcomes. Collapsin response mediator protein 2 (CRMP2) was first identified as a key mediator of axonal growth and guidance is essential for neurogenesis and neuroregeneration. Phosphorylation as a primary modification approach of CRMP2 facilitates its involvement in numerous physiological processes, including axonal guidance, neuroplasticity, and cytoskeleton dynamics. Prior research on CRMP2 phosphorylation has elucidated its involvement in the mechanisms of neurodegenerative diseases and nerve damage. Pharmacological and genetic interventions that alter CRMP2 phosphorylation have shown the potential to influence neurodegenerative diseases and promote nerve regeneration. Even with decades of research delving into the intricacies of CRMP2 phosphorylation, there remains a scarcity of comprehensive literature reviews addressing this topic. This absence of synthesis and integration of findings hampers the field's progress by preventing a holistic understanding of CRMP2's implications in neurobiology, thereby impeding potential advancements in clinical treatments and interventions. This review intends to compile investigations focused on the role of CRMP2 phosphorylation in both neurodegenerative disease models and injury models to summarizing impacts and offer novel insight for clinical therapies.

Cornus officinalis Sieb. Et Zucc. attenuates Aβ25-35-induced mitochondrial damage and neuroinflammation in mice by modulating the ERK pathway

BACKGROUND

Cornus officinalis Sieb. Et Zucc. has the efficacy of tonifying the marrow and filling up the essence, breaking up the accumulation and opening up the orifices. Our research team found that CoS extracts were protective against Aβ25-35-induced memory impairment in mice. However, the pharmacodynamic components and mechanisms by which CoS improves AD have yet to be thoroughly explored and investigated.

PURPOSE

This study focused on exploring the bioactive components and pharmacodynamic mechanisms of CoS aqueous extract underlying mitochondrial damage and neuroinflammation to improve Aβ25-35-induced AD.

METHODS

AD mouse models were generated using Aβ25-35 brain injections. Different doses of CoS aqueous extract were orally administered to mice for 28 days. The cognitive function, neuronal and synaptic damage, mitochondrial damage (mitochondrial length, mitochondrial fusion fission-related protein expression), neuroglial activation, and immune inflammatory factor and ERK pathway-related protein levels of mice were assessed. The CoS aqueous extracts components were identified using UPLC-TQ/MS and screened for cellular activity. Midivi-1 (Drp1 inhibitor) or PD98059 (ERK inhibitor) was added to Aβ25-35-exposed PC12 cells to assess whether CoS and its active compounds mMorB and CorE regulate mitochondrial fission through ERK/Drp1. PC12-N9 cells were cocultured to investigate whether mMorB and CorE could regulate mitochondrial division through the ERK pathway to modulate neuroinflammation.

RESULTS

CoS improved exploration and memory in AD mice, reduced synaptic and mitochondrial damage in their hippocampus, and modulated disturbed mitochondrial dynamics. Moreover, CoS inhibited ERK pathway signaling and attenuated abnormal activation of glial cells and secondary immune inflammatory responses. Additionally, in vitro experiments revealed that CoS and its compounds 7β-O-methylmorroniside (mMorB) and Cornusdiridoid E (CorE) ameliorated mitochondrial injury caused by Aβ25-35 in PC12 cells through inhibition of the ERK/Drp1 pathway. Meanwhile, mMorB and CorE ameliorated cellular inflammation by inhibiting the Ras/ERK/CREB signaling pathway.

CONCLUSION

CoS aqueous extract ameliorates behavioral deficits and brain damage in Aβ25-35-induced AD mice by modulating the ERK pathway to attenuate mitochondrial damage and neuroinflammation, and the compounds mMorB and CorE are the therapeutically active ingredients.

Concise Total Synthesis of Complanadine A Enabled by Pyrrole-to-Pyridine Molecular Editing

Lycopodium alkaloid complanadine A, isolated by Kobayashi et al. in 2000, is a complex and unsymmetrical dimer of lycodine. Biologically, it is a novel and promising lead compound for the development of new treatment for neurodegenerative disorders and persistent pain management. Herein, we reported a concise synthesis of complanadine A using a pyrrole-to-pyridine molecular editing strategy. The use of a nucleophilic pyrrole as the precursor of the desired pyridine enabled an efficient and one-pot construction of the tetracyclic core skeleton of complanadine A and lycodine. The pyrrole group was then converted to a 3-chloropyridine via the Ciamician-Dennstedt one carbon ring expansion. A subsequent C-H arylation between the 3-chloropyridine and a pyridine N-oxide formed the unsymmetrical dimer, which was then advanced to complanadine A. Overall, from a readily available known compound, total synthesis of complanadine A was achieved in 11 steps. The pyrrole-to-pyridine molecular editing strategy enabled us to significantly enhance the overall synthetic efficiency. Additionally, as demonstrated by a Suzuki-Miyaura cross coupling, the 3-chloropyridine product from the Ciamician-Dennstedt rearrangement is amenable for further derivatization, offering an opportunity for simplified analog synthesis.

Over the Counter Supplements for Memory: A Review of Available Evidence

In 2021, the Global Brain Health Supplement Industry Market size was valued at US$7.6 billion. It is predicted to increase to US$15.59 billion by 2030. Memory and its enhancement are a segment of the market that comprised the highest global revenue share in 2021. In the USA alone, dietary supplement sales reached US$18 billion in 2018. The US Food and Drug Administration (FDA) does not have the authority to approve dietary supplements' safety, effectiveness, or labeling before products go on the market. The FDA often does not even review supplements before they go to market. Supplement manufacturers are thus responsible for ensuring their products are safe and that their claims are truthful. An extensive review of current supplements on the market was performed by surveying memory products for sale at local and national pharmacies and grocery stores. A list of 103 supplements was compiled and the ingredients in these memory supplements were reviewed. The 18 most common ingredients in these supplements were identified. Each of the supplements included at least one of the 18 most common ingredients. Scientific data relative to these ingredients and their effect on memory was searched using PubMed and Cochrane library databases. Currently, there is no compelling evidence for use of apoaequorin, coenzyme Q10, coffee extracts, L-theanine, omega-3 fatty acids, vitamin B6, vitamin B9, or vitamin B12 supplementation for memory. On the other hand, there is some current evidence for memory benefit from supplementation with ashwagandha, choline, curcumin, ginger, Lion's Mane, polyphenols, phosphatidylserine, and turmeric. There are current studies with mixed results regarding the benefit of carnitine, gingko biloba, Huperzine A, vitamin D, and vitamin E supplementation for memory. Dietary supplements geared toward improving cognition are a billion-dollar industry that continues to grow despite lacking a solid scientific foundation for their marketing claims. More rigorous studies are needed relative to the long-term use of these supplements in homogenous populations with standardized measurements of cognition. Health care providers need to be aware of any and all supplements their older adult patients may be consuming and be educated about their side effects and interactions with prescription medications. Lastly, the FDA needs to take an active position relative to monitoring marketed supplements regarding safety, purity and claims of efficacy.

Disease-Modifying Activity of Huperzine A on Alzheimer's Disease: Evidence from Preclinical Studies on Rodent Models

(1) Background: Huperzine A, a natural cholinesterase (AChE) inhibitor isolated from the Chinese herb Huperzia Serrata, has been used as a dietary supplement in the United States and a drug in China for therapeutic intervention on Alzheimer's disease (AD). This review aims to determine whether Huperzine A exerts disease-modifying activity through systematic analysis of preclinical studies on rodent AD models. (2) Methods: Sixteen preclinical studies were included based on specific criteria, and the methodological qualities were analyzed by SYRCLE's risk of bias tool. Some outcomes were meta-analyzed: latencies and time spent in quadrant of Morris water maze, soluble amyloid-β (Aβ) level measured by ELISA in the cortex and hippocampus, Aβ plaque numbers measured by immunohistochemistry in hippocampus, choline acetyltransferase (ChAT) activity, and AChE activity. Finally, the mechanisms of Huperzine A on AD models were summarized. (3) Conclusions: The outcomes showed that Huperzine A displayed AChE inhibition, ChAT activity enhancement, memory improvement, and Aβ decreasing activity, indicating the disease-modifying effect of Huperzine A. However, due to the uneven methodological quality, the results need to be rationally viewed, and extensively repeated.

Neurotransmitters and molecular chaperones interactions in cerebral malaria: Is there a missing link?

Plasmodium falciparum is responsible for the most severe and deadliest human malaria infection. The most serious complication of this infection is cerebral malaria. Among the proposed hypotheses that seek to explain the manifestation of the neurological syndrome in cerebral malaria is the vascular occlusion/sequestration/mechanic hypothesis, the cytokine storm or inflammatory theory, or a combination of both. Unfortunately, despite the increasing volume of scientific information on cerebral malaria, our understanding of its pathophysiologic mechanism(s) is still very limited. In a bid to maintain its survival and development, P. falciparum exports a large number of proteins into the cytosol of the infected host red blood cell. Prominent among these are the P. falciparum erythrocytes membrane protein 1 (PfEMP1), P. falciparum histidine-rich protein II (PfHRP2), and P. falciparum heat shock proteins 70-x (PfHsp70-x). Functional activities and interaction of these proteins with one another and with recruited host resident proteins are critical factors in the pathology of malaria in general and cerebral malaria in particular. Furthermore, several neurological impairments, including cognitive, behavioral, and motor dysfunctions, are known to be associated with cerebral malaria. Also, the available evidence has implicated glutamate and glutamatergic pathways, coupled with a resultant alteration in serotonin, dopamine, norepinephrine, and histamine production. While seeking to improve our understanding of the pathophysiology of cerebral malaria, this article seeks to explore the possible links between host/parasite chaperones, and neurotransmitters, in relation to other molecular players in the pathology of cerebral malaria, to explore such links in antimalarial drug discovery.

Functionalized Allopurinols Targeting Amyloid-Binding Alcohol Dehydrogenase Rescue Aβ-Induced Mitochondrial Dysfunction

Alzheimer's disease (AD) is the most common dementia affecting one in nine people over 65. Only a handful of small-molecule drugs and the anti-β amyloid (Aβ) antibody aducanumab are approved to treat AD. However, they only serve to reduce symptoms of advanced disease. Novel treatments administered early in disease progression before the accumulation of Aβ and tau reaches the threshold where neuroinflammation is triggered and irreversible neuronal damage occurs are more likely to provide effective therapy. There is a growing body of evidence implying that mitochondrial dysfunction occurs at an early stage of AD pathology. The mitochondrial enzyme amyloid-binding alcohol dehydrogenase (ABAD) binds to Aβ potentiating toxicity. Moreover, ABAD has been shown to be overexpressed in the same areas of the brain most affected by AD. Inhibiting the Aβ-ABAD protein-protein interaction without adversely affecting normal enzyme turnover is hypothesized to be a potential treatment strategy for AD. Herein, we conduct structure-activity relationship studies across a series of functionalized allopurinol derivatives to determine their ability to inhibit Aβ-mediated reduction of estradiol production from ABAD. The lead compound resulting from these studies possesses potent activity with no toxicity up to 100 μM, and demonstrates an ability to rescue defective mitochondrial metabolism in human SH-SY5Y cells and rescue both defective mitochondrial metabolism and morphology ex vivo in primary 5XFAD AD mouse model neurons.

Ginkgolides and Huperzine A for complementary treatment of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by gradual deterioration of cognitive function, memory, and inability to perform daily, social, or occupational activities. Its etiology is associated with the accumulation of β-amyloid peptides, phosphorylated tau protein, and neuroinflammatory and oxidative processes in the brain. Currently, there is no successful pharmacological treatment for AD. The few approved drugs are mainly aimed at treating the symptoms; however, due to the increasing discovery of etiopathological factors, there are great efforts to find new multifunctional molecules to slow down the course of this neurodegenerative disease. The commercial Ginkgo biloba formulation EGb 761® and Huperzine A, an alkaloid present in the plant Huperzia serrata, have shown in clinical trials to possess cholinergic and neuroprotective activities, including improvement in cognition, activities of daily living, and neuropsychiatric symptoms in AD patients. The purpose of this review is to expose the positive results of intervention with EGb 761® and Huperzine in patients with mild to moderate AD in the last 10 years, highlighting the pharmacological functions that justify their use in AD therapy.

A Synopsis of Multitarget Potential Therapeutic Effects of Huperzine A in Diverse Pathologies-Emphasis on Alzheimer's Disease Pathogenesis

Numerous challenges are confronted when it comes to the recognition of therapeutic agents for treating complex neurodegenerative diseases like Alzheimer's disease (AD). The perplexing pathogenicity of AD embodies cholinergic dysfunction, amyloid beta (Aβ) aggregation, neurofibrillary tangle formation, neuroinflammation, mitochondrial disruption along with vicious production of reactive oxygen species (ROS) generating oxidative stress. In this frame of reference, drugs with multi target components could prove more advantageous to counter complex pathological mechanisms that are responsible for AD progression. For as much as, medicinal plant based pharmaco-therapies are emerging as potential candidates for AD treatment keeping the efficacy and safety parameters in terms of toxicity and side effects into consideration. Huperzine A (Hup A) is a purified alkaloid compound extracted from a club moss called Huperzia serrata. Several studies have reported both cholinergic and non-cholinergic effects of this compound on AD with significant neuroprotective properties. The present review convenes cumulative demonstrations of neuroprotection provided by Hup A in in vitro, in vivo, and human studies in various pathologies. The underlying molecular mechanisms of its actions have also been discussed. However, more profound evidence would certainly promote the therapeutic implementation of this drug thus furnishing decisive insights into AD therapeutics and various other pathologies along with preventive and curative management.

Dietary biomolecules as promising regenerative agents for peripheral nerve injury: An emerging nutraceutical-based therapeutic approach

Peripheral nerve damage is a debilitating condition that can result in partial or complete functional loss as a result of axonal degeneration, as well as lifelong dependence. Many therapies have been imbued with a plethora of positive features while posing little risks. It is worth noting that these biomolecules work by activating several intrinsic pathways that are known to be important in peripheral nerve regeneration. Although the underlying mechanism is used for accurate and speedy functional recovery, none of them are without side effects. As a result, it is believed that effective therapy is currently lacking. The dietary biomolecules-based intervention, among other ways, is appealing, safe, and effective. Upregulation of transcription factors, neurotrophic factors, and growth factors such as NGF, GDNF, BDNF, and CTNF may occur as a result of these substances' dietary intake. Upregulation of the signaling pathways ERK, JNK, p38, and PKA has also been seen, which aids in axonal regeneration. Although several mechanistic approaches to understanding their involvement have been suggested, more work is needed to reveal the amazing properties of these biomolecules. We have discussed in this article that how different dietary biomolecules can help with functional recovery and regeneration after an injury. PRACTICAL APPLICATIONS: Based on the information known to date, we may conclude that treatment techniques for peripheral nerve injury have downsides, such as complications, donor shortages, adverse effects, unaffordability, and a lack of precision in efficacy. These difficulties cast doubt on their efficacy and raise severe concerns about the prescription. In this situation, the need for safe and effective therapeutic techniques is unavoidable, and dietary biomolecules appear to be a safe, cost-efficient, and effective way to promote nerve regeneration following an injury. The information on these biomolecules has been summarized here. Upregulation of transcription factors, neurotrophic factors, and growth factors, such as NGF, GDNF, BDNF, and CTNF, as well as the ERK, JNK, p38, and PKA, signaling pathways, may stimulate axonal regeneration.

Huperzine A and Its Neuroprotective Molecular Signaling in Alzheimer's Disease

Huperzine A (HupA), an alkaloid found in the club moss Huperzia serrata, has been used for centuries in Chinese folk medicine to treat dementia. The effects of this alkaloid have been attributed to its ability to inhibit the cholinergic enzyme acetylcholinesterase (AChE), acting as an acetylcholinesterase inhibitor (AChEI). The biological functions of HupA have been studied both in vitro and in vivo, and its role in neuroprotection appears to be a good therapeutic candidate for Alzheimer´s disease (AD). Here, we summarize the neuroprotective effects of HupA on AD, with an emphasis on its interactions with different molecular signaling avenues, such as the Wnt signaling, the pre- and post-synaptic region mechanisms (synaptotagmin, neuroligins), the amyloid precursor protein (APP) processing, the amyloid-β peptide (Aβ) accumulation, and mitochondrial protection. Our goal is to provide an integrated overview of the molecular mechanisms through which HupA affects AD.

Acetylcholinesterase Inhibitors in the Treatment of Neurodegenerative Diseases and the Role of Acetylcholinesterase in their Pathogenesis

Acetylcholinesterase (AChE) plays an important role in the pathogenesis of neurodegenerative diseases by influencing the inflammatory response, apoptosis, oxidative stress and aggregation of pathological proteins. There is a search for new compounds that can prevent the occurrence of neurodegenerative diseases and slow down their course. The aim of this review is to present the role of AChE in the pathomechanism of neurodegenerative diseases. In addition, this review aims to reveal the benefits of using AChE inhibitors to treat these diseases. The selected new AChE inhibitors were also assessed in terms of their potential use in the described disease entities. Designing and searching for new drugs targeting AChE may in the future allow the discovery of therapies that will be effective in the treatment of neurodegenerative diseases.

Targeting Common Signaling Pathways for the Treatment of Stroke and Alzheimer's: a Comprehensive Review

Neurodegenerative diseases such as stroke and Alzheimer's disease (AD) are two inter-related disorders that affect the neurons in the brain and central nervous system. Alzheimer's is a disease by undefined origin and causes. Stroke and its most common type, ischemic stroke (IS), occurs due to the blockade of cerebral blood vessels. As an important feature, both of disorders are associated with irreversible damages to the brain and nervous system. In this regard, finding common signaling pathways and the same molecular origin between these two diseases may be a promising way for their solution. On the basis of literature appraisal, the most common signaling cascades implicated in the pathogenesis of AD and stroke including notch, autophagy, inflammatory, and insulin signaling pathways were reviewed. Furthermore, current therapeutic strategies including natural and synthetic pharmaceuticals aiming modulation of respective signaling factors were scrutinized to ameliorate neural deficits in AD and stroke. Taken together, digging deeper in the common connections and signal targeting can be greatly helpful in understanding and unified treating of these disorders.

Surface Functionalization of PLGA Nanoparticles to Increase Transport across the BBB for Alzheimer’s Disease

Alzheimer’s disease (AD) is a chronic neurodegenerative disorder that accounts for about 60% of all diagnosed cases of dementia worldwide. Although there are currently several drugs marketed for its treatment, none are capable of slowing down or stopping the progression of AD. The role of the blood-brain barrier (BBB) plays a key role in the design of a successful treatment for this neurodegenerative disease. Nanosized particles have been proposed as suitable drug delivery systems to overcome BBB with the purpose of increasing bioavailability of drugs in the brain. Biodegradable poly (lactic-co-glycolic acid) nanoparticles (PLGA-NPs) have been particularly regarded as promising drug delivery systems as they can be surface-tailored with functionalized molecules for site-specific targeting. In this review, a thorough discussion about the most recent functionalization strategies based on PLGA-NPs for AD and their mechanisms of action is provided, together with a description of AD pathogenesis and the role of the BBB in brain targeting.

Role of natural products for the treatment of Alzheimer's disease

Negative psychological and physiological consequences of neurodegenerative disorders represent a high social and health cost. Among the neurodegenerative disorders Alzheimer's disease (AD) is recognized as a leading neurodegenerative condition and a primary cause of dementia in the elderlys. AD is considered as neurodegenerative disorder that progressively impairs cognitive function and memory. According to current epidemiological data, about 50 milLion people worldwide are suffering from AD. The primary symptoms of AD are almost inappreciable and usually comprise forgetfulness of recent events. Numerous processes are involved in the development of AD, for example oxidative stress (OS) mainly due to mitochondrial dysfunction, intracellular the accumulation of hyperphosphorylated tau (τ) proteins in the form of neurofibrillary tangles, excessive the accumulation of extracellular plaques of beta-amyloid (Aβ), genetic and environmental factors. Running treatments only attenuate symptoms and temporarily reduce the rate of cognitive progression associated with AD. This means that most treatments focus only on controlLing symptoms, particularly in the initial stages of the disease. In the past, the first choice of treatment was based on natural ingredients. In this sense, diverse natural products (NPs) are capable to decrease the symptoms and alleviate the development of several diseases including AD attracting the attention of the scientific community and the pharmaceutical industry. Specifically, numerous NPs including flavonoids, gingerols, tannins, anthocyanins, triterpenes and alkaloids have been shown anti-inflammatory, antioxidant, anti-amyloidogenic, and anti-choLinesterase properties. This review provide a summary of the pathogenesis and the therapeutic goals of AD. It also discusses the available data on various plants and isolated natural compounds used to prevent and diminish the symptoms of AD.

Huperzine A lowers intraocular pressure via the M3 mAChR and provides retinal neuroprotection via the M1 mAChR: a promising agent for the treatment of glaucoma

BACKGROUND

Glaucoma is a neurodegenerative disease that shares similar pathological mechanisms with Alzheimer's disease (AD). Drug treatments for glaucoma increasingly rely upon both lowering of intraocular pressure (IOP) and optic nerve protection, as lowering of IOP alone has been unsatisfactory. Huperzine A (HupA) is an acetylcholinesterase inhibitor (AChEI) used for AD. This study investigated the potential of HupA as a treatment for glaucoma.

METHODS

The ability of HupA to lower IOP via causing pupil constriction was assessed using New Zealand rabbits. The retinal neuroprotective effects of HupA were assessed in vivo using rat retinas subjected to ischemia-reperfusion (I/R) and in vitro using primary retinal neurons (PRNs) suffering from oxygen-glucose deprivation (OGD).

RESULTS

HupA caused pupil constriction in a dose-time dependent manner which was reversed by the nonselective muscarinic acetylcholine receptor (mAChR) antagonist atropine and the selective M3 mAChR antagonist 4-DAMP. However, HupA had no effect on isolated iris muscle tension and calcium flow indicating an indirect M3 mAChR mediated effect. HupA exerted a neuroprotective effect against I/R and OGD to attenuate the retinal pathological lesion, improve retinal neuronal cell viability, reverse oxidative stress injury by increasing GSH levels and SOD activity, and decreasing MDA content and reduce the retinal neuronal apoptosis by decreasing Bax/Bcl-2 ratio and caspase-3 expression with no effect on the calcium flow tests. The effects were abolished by atropine and the selective M1 mAChR antagonist pirenzepine in OGD-induced PRNs suggesting an indirect M1 mAChR-mediated effect via inhibiting AChE activity to increase endogenous ACh level. Furthermore, HupA increased phosphorylated AKT level and decreased the levels of phosphorylated JNK, P38 MAPK and ERK via M1 mAChR antagonists indicating an involvement of activating the M1 mAChR and the downstream AKT/MAPK signaling pathway in the protective effects of HupA.

CONCLUSIONS

HupA could significantly decrease IOP via activating M3 mAChR indirectly and produce retinal neuroprotective effect through M1 mAChR/AKT/MAPK by increasing endogenous ACh level. These investigations demonstrated that HupA was an effective drug in glaucoma treatment and the clinical application of HupA and other AChEIs for glaucoma patients should be further investigated.

Intranasal Nanoemulsions for Direct Nose-to-Brain Delivery of Actives for CNS Disorders

The treatment of various central nervous system (CNS) diseases has been challenging, despite the rapid development of several novel treatment approaches. The blood-brain barrier (BBB) is one of the major issues in the treatment of CNS diseases, having major role in the protection of the brain but simultaneously constituting the main limiting hurdle for drugs targeting the brain. Nasal drug delivery has gained significant interest for brain targeting over the past decades, wherein the drug is directly delivered to the brain by the trigeminal and olfactory pathway. Various novel and promising formulation approaches have been explored for drug targeting to the brain by nasal administration. Nanoemulsions have the potential to avoid problems, including low solubility, poor bioavailability, slow onset of action, and enzymatic degradation. The present review highlights research scenarios of nanoemulsions for nose-to-brain delivery for the management of CNS ailments classified on the basis of brain disorders and further identifies the areas that remain unexplored. The significance of the total dose delivered to the target region, biodistribution studies, and long-term toxicity studies have been identified as the key areas of future research.

Acylphloroglucinols with acetylcholinesterase inhibitory effects from the fruits of Eucalyptus robusta

Eleven new acylphloroglucinols, including six new formylated phloroglucinol-monoterpene meroterpenoids, eucalyprobusals A-F (1-6), one monomeric acylphloroglucinol, eucalyprobusone B (7), and four dimeric acylphloroglucinols, eucalyprobusones C-F (8-11) were purified from the fruits of Eucalyptus robusta. The establishment of the structures of 1-11 was achieved by a combination of NMR and HRESIMS data analyses, electron circular dichroism (ECD), and single-crystal X-ray diffraction. Compounds 6, 8, and an inseparable mixture of 10 and 11 were found to be potent AChE inhibitors with IC50 values of 3.22 ± 0.36, 3.82 ± 0.22, and 2.55 ± 0.28 μΜ, respectively. Possible interaction sites of 6, 8, 10, and 11 with AChE were investigated by means of molecular docking studies, and the results revealed that AChE residues Asn87, Ser125, Thr83, Tyr133, Tyr124, Tyr337, and Tyr341 played crucial roles in the observed activity of the aforementioned compounds.

Five novel and highly efficient endophytic fungi isolated from Huperzia serrata expressing huperzine A for the treatment of Alzheimer's disease

Huperzine A (Hup A) is an important drug for treating Alzheimer's disease (AD) and mainly extracted from the Huperzia serrata (Thunb.) Trevis. (Lycopodiaceae) (HS). Nevertheless, the content of Hup A in HS is very low of 0.007% with growing circle of 8 to 10 years, and the chemical synthesis of Hup A still has some insurmountable limitations in the industrialized production. So, the available resources of Hup A for clinical treatment of AD are scarce. The purpose of this work was to construct a biosynthesis platform based on the endophytic fungi from HS. In this work, five endophytic fungi Mucor racemosus NSH-D, Mucor fragilis NSY-1, Fusarium verticillioides NSH-5, Fusarium oxysporum NSG-1, and Trichoderma harzianum NSW-V were firstly found and isolated from the Chinese folk medicine HS, which were identified according to their morphological characteristics and nuclear ribosomal DNA ITS sequences. The highest efficient fungus could effectively biosynthesize Hup A in a liquid culture of 319.8 ± 0.17 mg/L which were 112 times higher than that of other reported conventional endophytic fungi. Moreover, these fungi with higher hereditary stability could possess the initial expressing ability of Hup A after 40 generations, and the expressed Hup A from these biosynthesis systems has prior physicochemical properties, a better inhibition activity of acetylcholinesterase and a lower cytotoxicity compared with the listed active pharmaceutical ingredients (APIs) of Hup A. These results provide promising alternative resources for producing Hup A at an industrial scale by biosynthesis, and it may also shed light on millions of AD patients. KEY POINTS: • Five novel endophytic fungi with high stability could highly express prior Hup A Graphical abstract.

Huperzine A and Huperzine B Production by Prothallus Cultures of Huperzia selago (L.) Bernh. ex Schrank et Mart

This is the first report of an efficient and effective procedure to optimize the biosynthesis of huperzine A (HupA) and huperzine B (HupB) in vitro from Huperzia selago gametophytes. Axenic tissue cultures were established using spores collected from the sporophytes growing in the wild. The prothalia were obtained after 7–18 months. Approximately 90 up to 100% of the gametophytes were viable and grew rapidly after each transfer on to a fresh medium every 3 months. The best biomass growth index for prothallus calculated on a fresh (FW) and dry weight (DW) basis, at 24 weeks of culture, was 2500% (FW) and 2200% (DW), respectively. The huperzine A content in the gametophytes was very high and ranged from 0.74 mg/g to 4.73 mg/g DW. The highest yield HupA biosynthesis at >4 mg/g DW was observed on W/S medium without growth regulators at 8 to 24 weeks of culture. The highest HupB content ranged from 0.10 mg/g to 0.52 mg/g DW and was obtained on the same medium. The results demonstrate the superiority of H. selago gametophyte cultures, with the level of HupA biosynthesis approximately 42% higher compared to sporophyte cultures and 35-fold higher than when the alkaloid was isolated from H. serrata, its current source for the pharmaceutical industry. Moreover, the biosynthesis of HupB was several-fold more efficient than in H. selago sporophytes growing in the wild. HPLC-HR-MS analyses of the extracts identified eight new alkaloids previously unreported in H. selago: deacetylfawcettine, fawcettimine, 16-hydroxyhuperzine B, deacetyllycoclavine, annopodine, lycopecurine, des-N-methylfastigiatine and flabelline.

Pharmacogenetic considerations when prescribing cholinesterase inhibitors for the treatment of Alzheimer's disease

INTRODUCTION

Cholinergic dysfunction, demonstrated in the late 1970s and early 1980s, led to the introduction of acetylcholinesterase inhibitors (AChEIs) in 1993 (Tacrine) to enhance cholinergic neurotransmission as the first line of treatment against Alzheimer's disease (AD). The new generation of AChEIs, represented by Donepezil (1996), Galantamine (2001) and Rivastigmine (2002), is the only treatment for AD to date, together with Memantine (2003). AChEIs are not devoid of side-effects and their cost-effectiveness is limited. An option to optimize the correct use of AChEIs is the implementation of pharmacogenetics (PGx) in the clinical practice.

AREAS COVERED

(i) The cholinergic system in AD, (ii) principles of AD PGx, (iii) PGx of Donepezil, Galantamine, Rivastigmine, Huperzine and other treatments, and (iv) practical recommendations.

EXPERT OPINION

The most relevant genes influencing AChEI efficacy and safety are APOE and CYPs. APOE-4 carriers are the worst responders to AChEIs. With the exception of Rivastigmine (UGT2B7, BCHE-K), the other AChEIs are primarily metabolized via CYP2D6, CYP3A4, and UGT enzymes, with involvement of ABC transporters and cholinergic genes (CHAT, ACHE, BCHE, SLC5A7, SLC18A3, CHRNA7) in most ethnic groups. Defective variants may affect the clinical response to AChEIs. PGx geno-phenotyping is highly recommended prior to treatment.

Differential blockade by huperzine A and donepezil of sympathetic nicotinic acetylcholine receptor-mediated nitrergic neurogenic dilations in porcine basilar arteries

Nicotinic acetylcholine receptor activation on the perivascular sympathetic nerves via axo-axonal interaction mechanism causes norepinephrine release, which triggers the neurogenic nitrergic relaxation in basilar arteries to meet the need of a brain. Donepezil and huperzine A, which are the cholinesterase inhibitors used for Alzheimer's disease therapy, exert controversial effects on nicotinic acetylcholine receptors. Therefore, we investigated how donepezil and huperzine A via the axo-axonal interaction regulate the neurogenic vasodilation of isolated porcine basilar arteries and define their action on different subtypes of the nicotinic acetylcholine receptor by using blood vessel myography, calcium imaging, and electrophysiological techniques. Both nicotine (100 μM) and transmural nerve stimulation (TNS, 8 Hz) induce NO-mediated dilation in the arteries. Nicotine-induced vasodilations were concentration-dependently inhibited by huperzine A and donepezil, with the former being 30 fold less potent than the latter. Both cholinesterase inhibitors weakly and equally decreased TNS-elicited nitrergic vasodilations. Neither huperzine A nor donepezil affected isoproterenol (a β adrenoceptor-agonist)- or sodium nitroprusside (a NO donor)-induced vasodilation. Further, huperzine A was less potent than donepezil in inhibiting nicotine-elicited calcium influxes in rodent superior cervical ganglionic neurons and inward currents in α7- and α3β2-nicotinic acetylcholine receptor-expressing Xenopus oocytes. In conclusion, huperzine A may exert less harmful effect over donepezil on maintaining brainstem circulation and on the nicotinic acetylcholine receptor-associated cognition deficits during treatment for Alzheimer's disease.

The use of Huperzia species for the treatment of Alzheimer's disease

Alzheimer's disease (AD), which relates to nervous degeneration, is the most popular form of memory loss. The pathogenesis of AD is not fully understood, and there are no therapies for this disorder. Some drugs have been used in clinical applications for preventing and treating AD, but they have significant adverse reactions. Therefore, there is a need to develop treatment for AD. Traditional medicine has used many medicinal plants to alleviate the symptoms of AD. Medicinal plants may reduce neurodegenerative disorders with fewer side effects than chemical drugs, and they are promising drug candidates for AD therapy. This review is the summary of the pathogenesis and treatments of AD and includes information about the chemistry and bioactivities of some medicinal plants from the Huperzia species, such as Huperzia saururus, Huperzia selago, Huperzia phlegmaria, Huperzia fargesii, Huperzia serrata, Huperzia reflexa and Huperzia quadrifariata, that are used for the treatment of AD. We searched literature, including Medline, Embase, Google Scholar and PubMed database, and did a bibliographic review of relevant articles. Key words included Huperzia species, huperzine, huperin, Huperzia and Alzheimer's disease. We found that the main bioactive compounds of the Huperzia species are alkaloids, which have shown significant effects on preventing the development of AD. They are new promising compounds against AD due to their antioxidant, anti-inflammatory and acetylcholinesterase inhibitory activities in the neural system. Our conclusion from this review is that the Huperzia species are potential source containing various pharmaceutical compounds for the treatment of AD.

In Vitro and In Silico Acetylcholinesterase Inhibitory Activity of Thalictricavine and Canadine and Their Predicted Penetration across the Blood-Brain Barrier

In recent studies, several alkaloids acting as cholinesterase inhibitors were isolated from Corydalis cava (Papaveraceae). Inhibitory activities of (+)-thalictricavine (1) and (+)-canadine (2) on human acetylcholinesterase (hAChE) and butyrylcholinesterase (hBChE) were evaluated with the Ellman's spectrophotometric method. Molecular modeling was used to inspect the binding mode of compounds into the active site pocket of hAChE. The possible permeability of 1 and 2 through the blood⁻brain barrier (BBB) was predicted by the parallel artificial permeation assay (PAMPA) and logBB calculation. In vitro, 1 and 2 were found to be selective hAChE inhibitors with IC50 values of 0.38 ± 0.05 µM and 0.70 ± 0.07 µM, respectively, but against hBChE were considered inactive (IC50 values > 100 µM). Furthermore, both alkaloids demonstrated a competitive-type pattern of hAChE inhibition and bind, most probably, in the same AChE sub-site as its substrate. In silico docking experiments allowed us to confirm their binding poses into the active center of hAChE. Based on the PAMPA and logBB calculation, 2 is potentially centrally active, but for 1 BBB crossing is limited. In conclusion, 1 and 2 appear as potential lead compounds for the treatment of Alzheimer's disease.

Why Are the Majority of Active Compounds in the CNS Domain Natural Products? A Critical Analysis

Small-molecule natural products (NPs) have a long and successful track record of providing first-in-class drugs and pharmacophore (scaffolds) in all therapeutic areas, serving as a bridge between modern and traditional medicine. This trajectory has been remarkably successful in three key areas of modern therapeutics: cancers, infections, and CNS diseases. Beginning with the discovery of morphine 200 years ago, natural products have remained the primary source of new drugs/scaffolds for CNS diseases. In this perspective, we address the question: why are the majority of active compounds in the CNS domain natural products? Our analysis indicates that ∼84% approved drugs for CNS diseases are NPs or NP-inspired, and interestingly, 20 natural products provided more than 400 clinically approved CNS drugs. We have discussed unique physicochemical properties of NPs and NP-inspired vis-à-vis synthetic drugs, isoform selectivity, and evolutionary relationship, providing a rationale for increasing focus on natural product driven discovery for next-generation drugs for neurodegenerative diseases.

Inhibition of C298S mutant of human aldose reductase for antidiabetic applications: Evidence from in silico elementary mode analysis of biological network model

Human aldose reductase (hAR) is the key enzyme in sorbitol pathway of glucose utilization and is implicated in the etiology of secondary complications of diabetes, such as, cardiovascular complications, neuropathy, nephropathy, retinopathy, and cataract genesis. It reduces glucose to sorbitol in the presence of NADPH and the major cause of diabetes complications could be the change in the osmotic pressure due to the accumulation of sorbitol. An activated form of hAR (activated hAR or ahAR) poses a potential obstacle in the development of diabetes drugs as hAR-inhibitors are ineffective against ahAR. The therapeutic efficacy of such drugs is compromised when a large fraction of the enzyme (hAR) undergoes conversion to the activated ahAR form as has been observed in the diabetic tissues. In the present study, attempts have been made to employ systems biology strategies to identify the elementary nodes of human polyol metabolic pathway, responsible for normal metabolic states, followed by the identification of natural potent inhibitors of the activated form of hAR represented by the mutant C298S for possible antidiabetic applications. Quantum Mechanical Molecular Mechanical docking strategy was used to determine the probable inhibitors of ahAR. Rosmarinic acid was found as the most potent natural ahAR inhibitor and warrants for experimental validation in the near future.

Intranasal delivery of Huperzine A to the brain using lactoferrin-conjugated N-trimethylated chitosan surface-modified PLGA nanoparticles for treatment of Alzheimer's disease

Background

Safe and effective delivery of therapeutic drugs to the brain is important for successful therapy of Alzheimer’s disease (AD).

Purpose

To develop Huperzine A (HupA)-loaded, mucoadhesive and targeted polylactide-co-glycoside (PLGA) nanoparticles (NPs) with surface modification by lactoferrin (Lf)-conjugated N-trimethylated chitosan (TMC) (HupA Lf-TMC NPs) for efficient intranasal delivery of HupA to the brain for AD treatment.

Methods

HupA Lf-TMC NPs were prepared using the emulsion–solvent evaporation method and optimized using the Box–Behnken design. The particle size, zeta potential, drug entrapment efficiency, adhesion and in vitro release behavior were investigated. The cellular uptake was investigated by fluorescence microscopy and flow cytometry. MTT assay was used to evaluate the cytotoxicity of the NPs. In vivo imaging system was used to investigate brain targeting effect of NPs after intranasal administration. The biodistribution of Hup-A NPs after intranasal administration was determined by liquid chromatography–tandem mass spectrometry.

Results

Optimized HupA Lf-TMC NPs had a particle size of 153.2±13.7 nm, polydispersity index of 0.229±0.078, zeta potential of +35.6±5.2 mV, drug entrapment efficiency of 73.8%±5.7%, and sustained release in vitro over a 48 h period. Adsorption of mucin onto Lf-TMC NPs was 86.9%±1.8%, which was significantly higher than that onto PLGA NPs (32.1%±2.5%). HupA Lf-TMC NPs showed lower toxicity in the 16HBE cell line compared with HupA solution. Qualitative and quantitative cellular uptake experiments indicated that accumulation of Lf-TMC NPs was higher than nontargeted analogs in 16HBE and SH-SY5Y cells. In vivo imaging results showed that Lf-TMC NPs exhibited a higher fluorescence intensity in the brain and a longer residence time than nontargeted NPs. After intranasal administration, Lf-TMC NPs facilitated the distribution of HupA in the brain, and the values of the drug targeting index in the mouse olfactory bulb, cerebrum (with hippocampus removal), cerebellum, and hippocampus were about 2.0, 1.6, 1.9, and 1.9, respectively.

Conclusion

Lf-TMC NPs have good sustained-release effect, adhesion and targeting ability, and have a broad application prospect as a nasal drug delivery carrier.

Annotinolide F and lycoannotines A-I, further Lycopodium alkaloids from Lycopodium annotinum

Seven lycopodine-type (annotinolide F and lycoannotines A-F), two lycodine-type (lycoannotines G and H), and one fawcettimine-type (lycoannotine I) previously undescribed naturally occurring Lycopodium alkaloids together with thirteen known ones were isolated from the whole plant of Lycopodium annotinum. Their structures and absolute configurations were determined by extensive spectroscopic methods, single-crystal X-ray diffraction, chemical transformation, and electronic circular dichroism (ECD) calculations. Among the isolates, annotinolide F, lycoannotines A and B are unusual 7,8-seco-lycopodane derivatives, and annotinolide F even further possesses a rare 8,5-lactone framework through a lactonization after the C-7/C-8 bond cleavage. Lycoannotine C is an uncommon 8,15-seco lycopodine-type alkaloid, whereas lycoannotine I represents the first example of a naturally occurring C-9/N bond cleavage product of fawcettimine-type alkaloid. Among them, only lycoannotine I was found to show considerable anti-butyrylcholinesterase (anti-BuChE) activity.

Fraction n-Butanol of Radix Notoginseng Protects PC12 Cells from Aβ25-35-Induced Cytotoxicity and Alleviates Cognitive Deficits in SAMP8 Mice by Attenuating Oxidative Stress and Aβ Accumulation

Chinese medicine has been used for Alzheimer's disease (AD) treatment for thousands of years with more effective and fewer side effects. Therefore, developing effective potential candidates from Chinese medicine against AD would be considered as critical and efficient therapy for AD treatment. This study was designed to evaluate the neuronal protective effect of fraction n-butanol (NB) of Radix Notoginseng on Aβ_25–35-induced PC12 cells, explore the effect of the tested fraction on spatial learning and memory, and characterize the impacts of fraction NB on antioxidant enzymes, Aβ production, and APP and BACE1 expressions. The results revealed that fraction NB could promote proliferation of PC12 cells and protect and rescue PC12 cells from Aβ_25–35-induced cell death. Moreover, fraction NB could improve spatial learning and memory impairments of senescence-accelerated prone8 (SAMP8) mice and attenuate oxidative stress and reduce the production of Aβ by inhibiting the expressions of APP and BACE1 in the brains of SAMP8 mice. The result of single dose acute toxicity assay showed that fraction NB had a mild toxicity in vivo. The pronounced actions against AD and in vivo low toxicity of fraction NB suggest that fraction NB may be a useful alternative to the current AD treatment.

Newly Developed Drugs for Alzheimer's Disease in Relation to Energy Metabolism, Cholinergic and Monoaminergic Neurotransmission

Current options for Alzheimer's disease (AD) treatment are based on administration of cholinesterase inhibitors (donepezil, rivastigmine, galantamine) and/or memantine, acting as an N-methyl-D-aspartate (NMDA). Therapeutic approaches vary and include novel cholinesterase inhibitors, modulators of NMDA receptors, monoamine oxidase (MAO) inhibitors, immunotherapeutics, modulators of mitochondrial permeability transition pores (mPTP), amyloid-beta binding alcohol dehydrogenase (ABAD) modulators, antioxidant agents, etc. The novel trends of AD therapy are focused on multiple targeted ligands, where mostly ChE inhibition is combined with additional biological properties, positively affecting neuronal energy metabolism as well as mitochondrial functions, and possessing antioxidant properties. The present review summarizes newly developed drugs targeting cholinesterase and MAO, as well as drugs affecting mitochondrial functions.

Phytochemicals from fern species: potential for medicine applications

Ferns are an important phytogenetic bridge between lower and higher plants. Historically they have been used in many ways by humans, including as ornamental plants, domestic utensils, foods, and in handicrafts. In addition, they have found uses as medicinal herbs. Ferns produce a wide array of secondary metabolites endowed with different bioactivities that could potentially be useful in the treatment of many diseases. However, there is currently relatively little information in the literature on the phytochemicals present in ferns and their pharmacological applications, and the most recent review of the literature on the occurrence, chemotaxonomy and physiological activity of fern secondary metabolites was published over 20 years ago, by Soeder (Bot Rev 51:442-536, 1985). Here, we provide an updated review of this field, covering recent findings concerning the bioactive phytochemicals and pharmacology of fern species.

Pharmacological Effects of Active Components of Chinese Herbal Medicine in the Treatment of Alzheimer's Disease: A Review

Alzheimer's disease (AD), the most common neurodegenerative disorder associated with dementia, not only severely decreases the quality of life for its victims, but also brings a heavy economic burden to the family and society. Unfortunately, few chemical drugs designed for clinical applications have reached the expected preventive or therapeutic effect so far, and combined with their significant side-effects, there is therefore an urgent need for new strategies to be developed for AD treatment. Traditional Chinese Medicine has accumulated many experiences in the treatment of dementia during thousands of years of practice; modern pharmacological studies have confirmed the therapeutic effects of many active components derived from Chinese herbal medicines (CHM). Ginsenoside Rg1, extracted from Radix Ginseng, exerts a [Formula: see text]-secretase inhibitor effect so as to decrease A[Formula: see text] aggregation. It can also inhibit the apoptosis of neuron cells. Tanshinone IIA, extracted from Radix Salviae miltiorrhizae, and baicalin, extracted from Radix Scutellariae[Formula: see text] can inhibit the oxidative stress injury in neuronal cells. Icariin, extracted from Epimedium brevicornum, can decrease A[Formula: see text] levels and the hyperphosphorylation of tau protein, and can also inhibit oxidative stress and apoptosis. Huperzine A, extracted from Huperzia serrata, exerts a cholinesterase inhibitor effect. Evodiamine, extracted from Fructus Evodiae, and curcumin, extracted from Rhizoma Curcumae Longae, exert anti-inflammatory actions. Curcumin can act on A[Formula: see text] and tau too. Due to the advantages of multi-target effects and fewer side effects, Chinese medicine is more appropriate for long-term use. In this present review, the pharmacological effects of commonly used active components derived from Chinese herbal medicines in the treatment of AD are discussed.

In Vitro Effects of Cognitives and Nootropics on Mitochondrial Respiration and Monoamine Oxidase Activity

Impairment of mitochondrial metabolism, particularly the electron transport chain (ETC), as well as increased oxidative stress might play a significant role in pathogenesis of Alzheimer's disease (AD). Some effects of drugs used for symptomatic AD treatment may be related to their direct action on mitochondrial function. In vitro effects of pharmacologically different cognitives (galantamine, donepezil, rivastigmine, 7-MEOTA, memantine) and nootropic drugs (latrepirdine, piracetam) were investigated on selected mitochondrial parameters: activities of ETC complexes I, II + III, and IV, citrate synthase, monoamine oxidase (MAO), oxygen consumption rate, and hydrogen peroxide production of pig brain mitochondria. Complex I activity was decreased by galantamine, donepezil, and memantine; complex II + III activity was increased by galantamine. None of the tested drugs caused significant changes in the rate of mitochondrial oxygen consumption, even at high concentrations. Except galantamine, all tested drugs were selective MAO-A inhibitors. Latrepirdine, donepezil, and 7-MEOTA were found to be the most potent MAO-A inhibitors. Succinate-induced mitochondrial hydrogen peroxide production was not significantly affected by the drugs tested. The direct effect of cognitives and nootropics used in the treatment of AD on mitochondrial respiration is relatively small. The safest drugs in terms of disturbing mitochondrial function appear to be piracetam and rivastigmine. The MAO-A inhibition by cognitives and nootropics may also participate in mitochondrial neuroprotection. The results support the future research aimed at measuring the effects of currently used drugs or newly synthesized drugs on mitochondrial functioning in order to understand their mechanism of action.

Mitochondrial dysfunction and cell death in neurodegenerative diseases through nitroxidative stress

Mitochondria are important for providing cellular energy ATP through the oxidative phosphorylation pathway. They are also critical in regulating many cellular functions including the fatty acid oxidation, the metabolism of glutamate and urea, the anti-oxidant defense, and the apoptosis pathway. Mitochondria are an important source of reactive oxygen species leaked from the electron transport chain while they are susceptible to oxidative damage, leading to mitochondrial dysfunction and tissue injury. In fact, impaired mitochondrial function is commonly observed in many types of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease, alcoholic dementia, brain ischemia-reperfusion related injury, and others, although many of these neurological disorders have unique etiological factors. Mitochondrial dysfunction under many pathological conditions is likely to be promoted by increased nitroxidative stress, which can stimulate post-translational modifications (PTMs) of mitochondrial proteins and/or oxidative damage to mitochondrial DNA and lipids. Furthermore, recent studies have demonstrated that various antioxidants, including naturally occurring flavonoids and polyphenols as well as synthetic compounds, can block the formation of reactive oxygen and/or nitrogen species, and thus ultimately prevent the PTMs of many proteins with improved disease conditions. Therefore, the present review is aimed to describe the recent research developments in the molecular mechanisms for mitochondrial dysfunction and tissue injury in neurodegenerative diseases and discuss translational research opportunities.

Casuarinines A-J, lycodine-type alkaloids from Lycopodiastrum casuarinoides

Ten new lycodine-type alkaloids, named casuarinines A-J (1-10), along with eight known analogues (11-18), were isolated from the whole plant of Lycopodiastrum casuarinoides . The new structures were established by spectroscopic methods and chemical transformations. Casuarinines A-D (1-4) and J (10) are common lycodine alkaloids possessing four connected six-membered rings, while tricyclic casuarinines E-H (5-8) are the piperidine ring cleavage products. In particular, casuarinine I (9) has an unprecedented five-membered tetrahydropyrrole ring instead of the piperidine ring. A plausible biosynthetic pathway to 9 is proposed. Among the compounds reported, casuarinine H (8) exhibited significant neuroprotective effect against hydrogen peroxide (H₂O₂)-induced neuronal cell damage in human neuroblastoma SH-SY5Y cells, while casuarinines C (3) and I (9) showed moderate inhibitory activity against acetylcholinesterase (AChE).

New Lycopodium alkaloids from Lycopodium obscurum

Three new Lycopodium alkaloids, obscurumines C-E (1–3), along with nine known compounds, were isolated from the club moss Lycopodium obscurum L. Structures of the new compounds were determined on the basis of their spectroscopic analysis and the relative configurations of 1 were established by X-ray crystallographic analysis. All the new isolates were tested for the acetylcholinesterase (AChE) inhibitory activity.