Galanthamine from Galanthus and other Amaryllidaceae--chemistry and biology based on traditional use

Dynamics of alkaloid accumulation in Narcissus cv. Hawera: a source of Sceletium-type alkaloids

The Sceletium-type alkaloids, known for their anxiolytic and antidepressant activities, have been recently found to be biosynthesized in Narcissus cv. Hawera, which is largely used as an ornamental plant. An alkaloid fraction enriched with Sceletium-type alkaloids from the plant has shown promising antidepressant and anxiolytic activities. In the present study, qualitative and quantitative analyses of the alkaloids in the plant organs were performed during one vegetation season by GC-MS. The alkaloid pattern and total alkaloid content was found to depend strongly on the stage of development and plant organ. The alkaloid content of bulbs was found to be highest during the dormancy period and lowest in sprouting bulbs. The leaves showed the highest alkaloid content during the intensive vegetative growth and lowest during flowering. In total, 13 alkaloids were detected in the methanol extracts of Narcissus cv. Hawera, six Sceletium-type and seven typical Amaryllidaceae alkaloids. Major alkaloids in the alkaloid pattern were lycorine, 6-epi-mesembrenol, mesembrenone, sanguinine, and galanthamine. The leaves of flowering plants were found to have the highest amount of 6-epi-mesembrenol. Mesembrenone was found to be dominant alkaloid in the leaves of sprouting bulbs and in the flowers. Considering the biomass of the plant, the dormant bulbs are the best source of alkaloid fractions enriched with 6-epi-mesembrenol. The flowers and the young leaves can be used for preparation of alkaloid fractions enriched with mesembrenone. The results indicates that Narcissus cv. Hawera is an emerging source of valuable bioactive compounds and its utilization can be extended as a medicinal plant.

Variability in morphology, phytochemicals and antioxidant activity in Bistorta amplexicaulis (D. Don) Greene populations under variable habitats and altitudes

Phytochemicals have become significantly important for scientific research since these possess incredibly remarkable health benefits, especially antioxidant potential to scavenge free radicals and combat the harmful effects of oxidative stress caused by adverse environmental factors. The efficacy and quantity of these phytochemicals relies upon numerous factors including the extraction method, solvent polarity and the habitat features in which the plant is growing. In this study we emphasized on phytochemical analysis and antioxidant activity of Bistorta amplexicaulis, an important medicinal plant species from Kashmir Himalaya. We evaluated antioxidant activity using different assays from all the selected sites to enumerate the impact of habitat. The sites were selected based on varying habitat features and altitude. Our results revealed that Ethyl acetate is the potent solvent for the extraction of phytochemicals. Below ground parts exhibited better scavenging activity than the above ground parts. Amongst the sites, we found the maximum antioxidant potential at Site I. A positive correlation was found between antioxidant activity and altitude while soil attributes (OC, OM, N, P, and K) and most of the morphological traits showed a negative correlation. Overall, our study identified the elite populations that could be utilized for mass propagation and harness the ultimate antioxidant potential of B. amplexicaulis.

The quest for Homer's moly: exploring the potential of an early ethnobotanical complex

The Homeric plant moly is a mysterious herb mentioned in Book 10 of the Odyssey. In the early 1980s, a pharmacological thesis to identify the plant was put forward for the first time, regarding the snowdrop (Galanthus nivalis L.) as candidate species. The proposal was inspired by the snowdrop's acetylcholinesterase (AChE)-inhibiting properties and its alleged morphological reminiscence to other plants called moly by ancient Greek herbalists. Here, we draw from a compilation of literature from various disciplines, together with an understanding of the Homeric epic as a repository of information based on oral traditions, to (i) show that the assimilation of Homer's moly to Galanthus nivalis is, at the very least, questionable and (ii) frame and support a new synthesis of the pharmacological thesis. We suggest that the uncertainty that revolves around the identity of Homer's moly can be tied to an unnamed phylogenetic clade of closely related Mediterranean native species with AChE-inhibiting properties. Further, we speculate that Homer's moly might represent an early record of an ethnobotanical complex, a sort of cultural taxon resulting from the cognitive crossbreeding of closely related taxonomic species that could have been interchangeably used due to their rough resemblance and common AChE-inhibiting properties. Such cultural taxon would have referred to the phytonym moly by the centuries-old oral traditions that ultimately crystallized in the poem. We also venture that sea daffodils (Pancratium spp.) could have greatly contributed to shaping the botanical archetype in the myth as we know it today.

Polyphenol-enriched Desmodium elegans DC. ameliorate scopolamine-induced amnesia in animal model of Alzheimer's disease: In Vitro, In Vivo and In Silico approaches

The current study aims to quantify HPLC-DAD polyphenolics in the crude extracts of Desmodium elegans, evaluating its cholinesterase inhibitory, antioxidant, molecular docking and protective effects against scopolamine-induced amnesia in mice. A total of 16 compounds were identified which include gallic acid (239 mg g-1), p-hydroxybenzoic acid (11.2 mg g-1), coumaric acid (10.0 mg g-1), chlorogenic acid (10.88 mg g-1), caffeic acid (13.9 mg g-1), p-coumaroylhexose (41.2 mg g-1), 3-O-caffeoylquinic acid (22.4 mg g-1), 4-O-caffeoylquinic acid (6.16 mg g-1), (+)-catechin (71.34 mg g-1), (-)-catechin (211.79 mg g-1), quercetin-3-O-glucuronide (17.9 mg g-1), kaempferol-7-O-glucuronide (13.2 mg g-1), kaempferol-7-O-rutinoside (53.67 mg g-1), quercetin-3-rutinoside (12.4 mg g-1), isorhamnetin-7-O-glucuronide (17.6 mg g-1) and isorhamnetin-3-O-rutinoside (15.0 mg g-1). In a DPPH free radical scavenging assay, the chloroform fraction showed the highest antioxidant activity, with an IC50 value of 31.43 µg mL-1. In an AChE inhibitory assay, the methanolic and chloroform fractions showed high inhibitory activities causing 89% and 86.5% inhibitions with IC50 values of 62.34 and 47.32 µg mL-1 respectively. In a BChE inhibition assay, the chloroform fraction exhibited 84.36% inhibition with IC50 values of 45.98 µg mL-1. Furthermore, molecular docking studies revealed that quercetin-3-rutinoside and quercetin-3-O-glucuronide fit perfectly in the active sites of AChE and BChE respectively. Overall, the polyphenols identified exhibited good efficacy, which is likely as a result of the compounds' electron-donating hydroxyl groups (-OH) and electron cloud density. The administration of methanolic extract improved cognitive performance and demonstrated anxiolytic behavior among tested animals.

Palladium-Catalyzed Synthesis, Acetylcholinesterase Inhibition, and Neuroprotective Activities of N-Aryl Galantamine Analogues

A series of new N-aryl galantamine analogues (5a-5x) were designed and synthesized by modification of galantamine, using Pd-catalyzed Buchwald-Hartwig cross-coupling reaction in good to excellent yields. The cholinesterase inhibitory and neuroprotective activities of N-aryl derivatives of galantamine were evaluated. Among the synthesized compounds, the 4-methoxylpyridine-galantamine derivative (5q) (IC₅₀ = 0.19 μM) exhibited excellent acetylcholinesterase inhibition activity, as well as significant neuroprotective effect against H₂O₂-induced injury in SH-SY5Y cells. Molecular docking, staining, and Western blotting analyses were performed to demonstrate the mechanism of action of 5q. Derivative 5q would be a promising multifunctional lead compound for the treatment of Alzheimer's disease.

Antiviral alkaloid principles of the plant family Amaryllidaceae

BACKGROUND

Viral-borne diseases are amongst the oldest diseases known to mankind. They are responsible for some of the most ravaging effects wrought on human health and well-being. The use of plants against these ailments is entrenched in both traditional and secular medicine around the globe. Their natural abundance and chemical diversity have also boosted their appeal in drug discovery.

AIM

The plant family Amaryllidaceae is distinguished for its alkaloid principles, some of which are of considerable interest in the clinical arena. This account is the outcome of a literature review undertaken to establish the applicability of these substances as antiviral agents.

METHODS

The survey utilized the search engines Google Scholar, PubMed, SciFinder, Scopus and Web of Science engaging the word 'antiviral' in conjunction with 'Amaryllidaceae' and 'Amaryllidaceae alkaloid'. The search returned over five hundred hits, of which around eighty were of relevance to the theme of the text.

RESULTS

Over eighty isoquinoline alkaloids have been screened against nearly fifty pathogens from fourteen viral families, the majority of which were RNA viruses. Potent activities were reported in some instances, such as that of trans-dihydronarciclasine against Yellow fever virus (IC₅₀ 0.003 μg/ml), with minimal effects being manifested on host cells. There were also promising results obtained from in vivo studies, in most cases without lethal effects on test subjects. Structure-activity relationship studies afforded useful insight to the antiviral pharmacophore, with the phenanthridone alkaloid nucleus shown to be the most enabling. Although the mechanistic basis to these activities pertained mostly to inhibition of DNA, RNA and protein synthesis, evidence was also forthcoming about the inhibitory action of some of the alkaloids against viral neuraminidase, protease and reverse transcriptase. In silico methods of analysis have offered further perspectives of how some of the alkaloids interact at the active sites of their targets.

CONCLUSION

The Amaryllidaceae offers a viable platform for plant-based antiviral drug discovery. Its cause is strengthened not only by its wide proliferation and exploitation of its members in alternative forms of medicine, but also by its rich chemical diversity which has already spawned useful antiviral drug leads.

The Phytochemistry and Pharmacology of Tulbaghia, Allium, Crinum and Cyrtanthus: ‘Talented’ Taxa from the Amaryllidaceae

Amaryllidaceae is a significant source of bioactive phytochemicals with a strong propensity to develop new drugs. The genera Allium, Tulbaghia, Cyrtanthus and Crinum biosynthesize novel alkaloids and other phytochemicals with traditional and pharmacological uses. Amaryllidaceae biomolecules exhibit multiple pharmacological activities such as antioxidant, antimicrobial, and immunomodulatory effects. Traditionally, natural products from Amaryllidaceae are utilized to treat non-communicable and infectious human diseases. Galanthamine, a drug from this family, is clinically relevant in treating the neurocognitive disorder, Alzheimer’s disease, which underscores the importance of the Amaryllidaceae alkaloids. Although Amaryllidaceae provide a plethora of biologically active compounds, there is tardiness in their development into clinically pliable medicines. Other genera, including Cyrtanthus and Tulbaghia, have received little attention as potential sources of promising drug candidates. Given the reciprocal relationship of the increasing burden of human diseases and limited availability of medicinal therapies, more rapid drug discovery and development are desirable. To expedite clinically relevant drug development, we present here evidence on bioactive compounds from the genera Allium, Tulgbaghia, Cyrtanthus and Crinum and describe their traditional and pharmacological applications.

Exploring the Therapeutic Potential of Phytochemicals in Alzheimer’s Disease: Focus on Polyphenols and Monoterpenes

Alzheimer’s disease (AD) is a chronic, complex neurodegenerative disorder mainly characterized by the irreversible loss of memory and cognitive functions. Different hypotheses have been proposed thus far to explain the etiology of this devastating disorder, including those centered on the Amyloid-β (Aβ) peptide aggregation, Tau hyperphosphorylation, neuroinflammation and oxidative stress. Nonetheless, the therapeutic strategies conceived thus far to treat AD neurodegeneration have proven unsuccessful, probably due to the use of single-target drugs unable to arrest the progressive deterioration of brain functions. For this reason, the theoretical description of the AD etiology has recently switched from over-emphasizing a single deleterious process to considering AD neurodegeneration as the result of different pathogenic mechanisms and their interplay. Moreover, much relevance has recently been conferred to several comorbidities inducing insulin resistance and brain energy hypometabolism, including diabetes and obesity. As consequence, much interest is currently accorded in AD treatment to a multi-target approach interfering with different pathways at the same time, and to life-style interventions aimed at preventing the modifiable risk-factors strictly associated with aging. In this context, phytochemical compounds are emerging as an enormous source to draw on in the search for multi-target agents completing or assisting the traditional pharmacological medicine. Intriguingly, many plant-derived compounds have proven their efficacy in counteracting several pathogenic processes such as the Aβ aggregation, neuroinflammation, oxidative stress and insulin resistance. Many strategies have also been conceived to overcome the limitations of some promising phytochemicals related to their poor pharmacokinetic profiles, including nanotechnology and synthetic routes. Considering the emerging therapeutic potential of natural medicine, the aim of the present review is therefore to highlight the most promising phytochemical compounds belonging to two major classes, polyphenols and monoterpenes, and to report the main findings about their mechanisms of action relating to the AD pathogenesis.

In vitro and in silico analysis of galanthine from Zephyranthes carinata as an inhibitor of acetylcholinesterase

Zephyranthes carinata Herb., a specie of the Amaryllidoideae subfamily, has been reported to have inhibitory activity against acetylcholinesterase. However, scientific evidence related to their bioactive alkaloids has been lacking. Thus, this study describes the isolation of the alkaloids of this plant, and their inhibition of the enzymes acetylcholinesterase (eeAChE) and butyrylcholinesterase (eqBuChE), being galanthine the main component. Additionally, haemanthamine, hamayne, lycoramine, lycorine, tazettine, trisphaeridine and vittatine/crinine were also isolated. The results showed that galanthine has significant activity at low micromolar concentrations for eeAChE (IC₅₀ = 1.96 μg/mL). The in-silico study allowed to establish at a molecular level the high affinity and the way galanthine interacts with the active site of the TcAChE enzyme, information that corroborates the result of the experimental IC₅₀. However, according to molecular dynamics (MD) analysis, it is also suggested that galanthine presents a different inhibition mode that the one observed for galanthamine, by presenting interaction with peripheral anionic binding site of the enzyme, which prevents the entrance and exit of molecules from the active site. Thus, in vitro screening assays plus rapid computer development play an essential role in the search for new cholinesterase inhibitors by identifying unknown bio-interactions between bioactive compounds and biological targets.

Natural Polysaccharides as Preventive and Therapeutic Horizon for Neurodegenerative Diseases

Neurodegenerative diseases are a serious and widespread global public health burden amongst aging populations. The total estimated worldwide global cost of dementia was US$818 billion in 2015 and has been projected to rise to 2 trillion US$ by 2030. While advances have been made to understand different neurodegenerative disease mechanisms, effective therapeutic strategies do not generally exist. Several drugs have been proposed in the last two decades for the treatment of different types of neurodegenerative diseases, with little therapeutic benefit, and often with severe adverse and side effects. Thus, the search for novel drugs with higher efficacy and fewer drawbacks is an ongoing challenge in the treatment of neurodegenerative disease. Several natural compounds including polysaccharides have demonstrated neuroprotective and even therapeutic effects. Natural polysaccharides are widely distributed in plants, animals, algae, bacterial and fungal species, and have received considerable attention for their wide-ranging bioactivity, including their antioxidant, anti-neuroinflammatory, anticholinesterase and anti-amyloidogenic effects. In this review, we summarize different mechanisms involved in neurodegenerative diseases and the neuroprotective effects of natural polysaccharides, highlighting their potential role in the prevention and therapy of neurodegenerative disease.

Biological Investigation of Amaryllidaceae Alkaloid Extracts from the Bulbs of Pancratium trianthum Collected in the Senegalese Flora

Amaryllidaceae plants are rich in alkaloids with biological properties. Pancratium trianthum is an Amaryllidaceae species widely used in African folk medicine to treat several diseases such as central nervous system disorders, tumors, and microbial infections, and it is used to heal wounds. The current investigation explored the biological properties of alkaloid extracts from bulbs of P. trianthum collected in the Senegalese flora. Alkaloid extracts were analyzed and identified by chromatography and mass spectrometry. Alkaloid extracts from P. trianthum displayed pleiotropic biological properties. Cytotoxic activity of the extracts was determined on hepatocarcinoma Huh7 cells and on acute monocytic leukemia THP-1 cells, while agar diffusion and microdilution assays were used to evaluate antibacterial activity. Antiviral activity was measured by infection of extract-treated cells with dengue virus (DENV_GFP) and human immunodeficiency virus-1 (HIV-1_GFP) reporter vectors. Cytotoxicity and viral inhibition were the most striking of P. trianthum’s extract activities. Importantly, non-cytotoxic concentrations were highly effective in completely preventing DENV_GFP replication and in reducing pseudotyped HIV-1_GFP infection levels. Our results show that P. trianthum is a rich source of molecules for the potential discovery of new treatments against various diseases. Herein, we provide scientific evidence to rationalize the traditional uses of P. trianthum for wound treatment as an anti-dermatosis and antiseptic agent.

Tradition to Pathogenesis: A Novel Hypothesis for Elucidating the Pathogenesis of Diseases Based on the Traditional Use of Medicinal Plants

Traditional medicines embody knowledge on medicinal plants that has been accumulated through cultural evolution over millennia. In the latter half of the 20th century, two approaches to medicinal plant research have been established: the "Bench to Bedside" and the "Bedside to Bench" approaches which serve primarily for the development of more efficient therapeutics. Here, we propose a third, novel approach: from "Tradition to Pathogenesis" which aims to understand the pathogenesis of diseases based on the cultural evolution of their respective empirical treatments. We analyse multiple examples of diseases where the acting mechanism of traditional treatments across multiple cultures points to the pathogenesis of the respective disease. E.g., many cultures traditionally treat rheumatism with anti-bacterial botanical drugs, which is at odds with our current understanding that rheumatism is an aseptic inflammation. Furthermore, gastric ailments have traditionally been treated with anti-infectious botanical drugs indicating local infections, as demonstrated by the discovery of Helicobacter pylori as a common cause of gastric ulcer. Understanding traditional treatments can thus help to elucidate the pathogenesis of the disease.

Harnessing Drug Repurposing for Exploration of New Diseases: An Insight to Strategies and Case Studies

BACKGROUND

Traditional drug discovery is time consuming, costly, and risky process. Owing to the large investment, excessive attrition, and declined output, drug repurposing has become a blooming approach for the identification and development of new therapeutics. The method has gained momentum in the past few years and has resulted in many excellent discoveries. Industries are resurrecting the failed and shelved drugs to save time and cost. The process accounts for approximately 30% of the new US Food and Drug Administration approved drugs and vaccines in recent years.

METHODS

A systematic literature search using appropriate keywords were made to identify articles discussing the different strategies being adopted for repurposing and various drugs that have been/are being repurposed.

RESULTS

This review aims to describe the comprehensive data about the various strategies (Blinded search, computational approaches, and experimental approaches) used for the repurposing along with success case studies (treatment for orphan diseases, neglected tropical disease, neurodegenerative diseases, and drugs for pediatric population). It also inculcates an elaborated list of more than 100 drugs that have been repositioned, approaches adopted, and their present clinical status. We have also attempted to incorporate the different databases used for computational repurposing.

CONCLUSION

The data presented is proof that drug repurposing is a prolific approach circumventing the issues poised by conventional drug discovery approaches. It is a highly promising approach and when combined with sophisticated computational tools, it also carries high precision. The review would help researches in prioritizing the drugrepositioning method much needed to flourish the drug discovery research.

Acetylcholinesterase Inhibitory Potential of Various Sesquiterpene Analogues for Alzheimer's Disease Therapy

Alzheimer's disease (AD) is a gradually growing irreversible illness of the brain that almost affects every fifth person (aged > 80 years) in the world. World Health Organization (WHO) also revealed that the prevalence of this disease will enhance (upto double) significantly upto 2030. The poor cholinergic transmission at the synapse is considered to be one of the main reasons behind the progression and occurrence of this disorder. Natural inhibitors of acetylcholine (ACh) such as galanthamine and rivastigmine are used commercially in the treatmentof AD. The biomolecules such assesquiterpenes, possess a great structural diversity and are responsible for a plethora of pharmacological properties. The potential of various sesquiterpenes as anticholinesterase has been reviewed in this article. For this purpose, the various databases, mainly PubMed, Scopus, and Web of Science were investigatedwith different keywords such as "sesquiterpenes+acetylcholinesterase" and "sesquiterpenes+cholinesterase+inhibitors" in the surveyed time frame (2010-2020). A vast literature was evident in the last decade, which affirms the potential of various sesquiterpenes in the improvement of cholinergic transmission by inhibiting the AChE. After data analysis, it was found that 12 compounds out of a total of 58 sesquiterpenes were reported to possess IC50 < 9μM and can be considered as potential candidates for the improvement of learning and memory. Sesquiterpene is an important category of terpenoids, found to possess a large spectrum of biological activities. The outcome of the review clearly states that sesquiterpenes (such as amberboin, lipidiol,etc) from herbs could offer fresh, functional compounds for possible prevention and treatment of AD.

Phytochemical Analysis, In Vitro Anticholinesterase, Antioxidant Activity and In Vivo Nootropic Effect of Ferula ammoniacum (Dorema ammoniacum) D. Don. in Scopolamine-Induced Memory Impairment in Mice

Background: Ferula ammoniacum (D. Don) is one of the endemic medicinal plants that is traditionally used to treat a number of diseases. Although the plant has been used to enhance memory, the investigational evidence supporting the nootropic effect was unsubstantial. Hence, the rationale for this study was to assess the potential beneficial effect of F. ammoniacum seed extracts on learning and memory in mice. Methods: The powdered plant samples (aerial parts) were subjected to extraction ad fractionation. Among the extracts, crude and ethyl acetate extracts were screened for major phytochemicals through HPLC analysis. All the extracts were evaluated for the in vitro anticholinesterase (AChE and BChE) and antioxidant potentials. Among the extracts the active fraction was further assessed for improving learning and memory in mice using behavioural tests like Y-maze and novel object recognition test (NORT) using standard protocols. After behavioural tests, all the animals were sacrificed and brains tissues were assessed for the ex vivo anticholinesterase and antioxidant potentials. Results: Phytochemicals like chlorogenic acid, quercetin, mandelic acid, phloroglucinol, hydroxy benzoic acid, malic acid, epigallocatechin gallate, ellagic acid, rutin, and pyrogallol were identified in crude methanolic extract (Fa.Met) and ethyl acetate fraction (Fa.EtAc) through HPLC. Fa.EtAc and Fa.Chf extracts more potently inhibited AChE and BChE with IC50 values of 40 and 43 µg/mL, and 41 and 42 µg/mL, respectively. Similarly highest free radical scavenging potential was exhibited by Fa.EtAc fraction against DPPH (IC50 = 100 µg/mL) and ABTS (IC50 = 120 µg/mL). The extract doses, 100 and 200 mg/kg body weight significantly (p < 0.01) improved the short-term memory by increasing the percent spontaneous alternation in the Y-maze test along with increasing discrimination index in the NORT that clearly indicated the enhancement in the recognition memory of mice. Conclusion: The extracts more potently scavenged the tested free radicals, exhibited anticholinesterase activities, improved the learning abilities and reduced the memory impairment induced by scopolamine in mice model thus suggesting that these extracts could be effectively used for the management of oxidative stress, neurodegenerative diseases and memory loss.

Biological Activities of Snowdrop (Galanthus spp., Family Amaryllidaceae)

Snowdrop is an iconic early spring flowering plant of the genus Galanthus (Amaryllidaceae). Galanthus species (Galanthus spp.) are economically important plants as ornaments. Galanthus spp has gained significance scientific and commercial interest due to the discovery of Galanthamine as symptomatic treatment drug for Alzhiermer disease. This review aims to discuss the bioactivities of Galanthus spp including anticholinesterase, antimicrobial, antioxidant and anticancer potential of the extracts and chemical constituents of Galanthus spp. This review highlights that Galanthus spp. as the exciting sources for drug discovery and nutraceutical development.

Biosynthesis and Biological Activities of Newly Discovered Amaryllidaceae Alkaloids

Alkaloids are an important group of specialized nitrogen metabolites with a wide range of biochemical and pharmacological effects. Since the first publication on lycorine in 1877, more than 650 alkaloids have been extracted from Amaryllidaceae bulbous plants and clustered together as the Amaryllidaceae alkaloids (AAs) family. AAs are specifically remarkable for their diverse pharmaceutical properties, as exemplified by the success of galantamine used to treat the symptoms of Alzheimer's disease. This review addresses the isolation, biological, and structure activity of AAs discovered from January 2015 to August 2020, supporting their therapeutic interest.

Naturally Occurring Acetylcholinesterase Inhibitors and Their Potential Use for Alzheimer's Disease Therapy

Alzheimer's disease (AD) is a main cause of dementia, accounting for up to 75% of all dementia cases. Pathophysiological processes described for AD progression involve neurons and synapses degeneration, mainly characterized by cholinergic impairment. This feature makes acetylcholinesterase inhibitors (AChEi) the main class of drugs currently used for the treatment of AD dementia phase, among which galantamine is the only naturally occurring substance. However, several plant species producing diverse classes of alkaloids, coumarins, terpenes, and polyphenols have been assessed for their anti-AChE activity, becoming potential candidates for new anti-AD drugs. Therefore, this mini-review aimed to recapitulate last decade studies on the anti-AChE activity of plant species, their respective extracts, as well as isolated compounds. The anti-AChE activity of extracts prepared from 54 plant species pertaining 29 families, as well as 36 isolated compounds were classified and discussed according to their anti-AChE pharmacological potency to highlight the most prominent ones. Besides, relevant limitations, such as proper antioxidant assessment, and scarcity of toxicological and clinical studies were also discussed in order to help researchers out with the bioprospection of potentially new AChEi.

Old Drugs as New Treatments for Neurodegenerative Diseases

Neurodegenerative diseases are increasing in number, given that the general global population is becoming older. They manifest themselves through mechanisms that are not fully understood, in many cases, and impair memory, cognition and movement. Currently, no neurodegenerative disease is curable, and the treatments available only manage the symptoms or halt the progression of the disease. Therefore, there is an urgent need for new treatments for this kind of disease, since the World Health Organization has predicted that neurodegenerative diseases affecting motor function will become the second-most prevalent cause of death in the next 20 years. New therapies can come from three main sources: synthesis, natural products, and existing drugs. This last source is known as drug repurposing, which is the most advantageous, since the drug’s pharmacokinetic and pharmacodynamic profiles are already established, and the investment put into this strategy is not as significant as for the classic development of new drugs. There have been several studies on the potential of old drugs for the most relevant neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, Multiple Sclerosis and Amyotrophic Lateral Sclerosis.

Antifungal Activity Based Studies of Amaryllidaceae Plant Extracts

The growth in demand for cosmetic, graft and organ transplant surgical procedures, the increased use of antineoplastic and immunosuppressive agents, as well as multidrug resistance are some of the factors responsible for the marked rise in fungal infection rates in recent years. Consequently, there have been renewed calls from both the public and private sectors for new and improved drug targets to replace existing antifungal therapies, many of which have been in clinical circulation for several decades. Plants select themselves in such endeavors owing to their superior numbers and vast chemical diversities. With this as a backdrop, this survey examines the antifungal activities of Amaryllidaceae plant extracts against various fungal pathogens. Good growth inhibitory activities (MICs <1 mg/mL) reported in several instances are noteworthy and could guide efforts targeting the active antifungal principles.

Traditional use of medicinal agents: a valid source of evidence

Traditional knowledge uncovered by serious historical research may help to identify new therapeutic agents. It also plays a part in safety evaluation and drug regulation. So far, however, this way of gaining knowledge is very much neglected in the concept of evidence based medicine, which is in no way contradictory to traditional use. Thus, the true meaning of the word 'tradition' is described, while reliable historical sources are quoted. It is then shown how research into the traditional use of medicinal plants is able to reveal knowledge about efficacy and safety of natural products. Several examples successfully leading to new therapeutic options are given. It is then referred to the concept of 'social validation' developed by the Canadian medical historian John Crellin, who also established guidelines for respective research. Eventually, it is proposed to modify the list of evidence levels by inserting an evidence level 4b 'Traditional use in more than one regional cluster'.

Traditional used Plants against Cognitive Decline and Alzheimer Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized clinically by progressive memory deficits, impaired cognitive function, and altered and inappropriate behavior. Aging represents the most important risk factor for AD and the global trend in the phenomenon of population aging has dramatic consequences for public health, healthcare financing, and delivery systems in the word and, especially in developing countries. Mounting evidence obtained in in vitro and in vivo studies, suggests that various traditionally used plants in Asia, India, and Europe significantly affect key metabolic alterations culminating in AD-typical neurodegeneration. The present article aims to bring the reader up-to-date on the most recent studies and advances describing the direct and indirect activities of traditional used plants and its constituents possibly relieving features of AD. A variety of traditional used plants and its extracts exerted activities on AD related drug targets including AChE activity, antioxidative activity, modulation of Aβ-producing secretase activities, Aβ-degradation, heavy metal chelating, induction of neurotrophic factors, and cell death mechanisms. Although pre-clinical investigations identified promising drug candidates for AD, clinical evidences are still pending.