Metabolite profile and in vitro activities of Phagnalon saxatile (L.) Cass. relevant to treatment of Alzheimer's disease

Mexican calea (Calea zacatechichi Schltdl.) interferes with cholinergic and dopaminergic pathways and causes neuroglial toxicity

ETHNOPHARMACOLOGICAL RELEVANCE

The use of "Mexican calea" (Calea zacatechichi Schltdl.) in ritualistic ceremonies, due to its dream-inducing effects, was until recently limited to indigenous communities in Mexico. However, the plant has recently gained popularity in Western societies being commonly used in recreational settings. Despite the traditional and recreational uses, mechanisms underlying its reported oneirogenic effects remain unknown, with no data available on its neurotoxic profile.

AIM OF THE STUDY

The scarcity of toxicological data and the unknown role of major neurotransmitter systems in the dream-inducing properties of the plant prompted us to investigate which neurotransmitters might be affected upon its consumption, as well as the potential cytotoxic effects on neurons and microglial cells. Furthermore, we aimed to explore a relationship between the recorded effects and specific constituents.

MATERIALS AND METHODS

Effects on cholinergic and monoaminergic pathways were investigated using enzymatic assays, with the latter also being conducted in neuronal SH-SY5Y cells along with the impact on glutamate-induced excitotoxicity. Investigation of the neurotoxic profile was approached in neuronal SH-SY5Y and microglial BV-2 cells, evaluating effects on metabolic performance and membrane integrity using MTT and LDH leakage assays, respectively. Potential interference with oxidative stress was monitored by assessing free radical's levels, as well as 5-lipoxygenase mediated lipid peroxidation. Phenolic constituents were identified through HPLC-DAD-ESI(Ion Trap)MSn analysis.

RESULTS

Based on the significant inhibition upon acetylcholinesterase (p < 0.05) and tyrosinase (IC50 = 60.87 ± 7.3 μg/mL; p < 0.05), the aqueous extract obtained from the aerial parts of C. zacatechichi interferes with the cholinergic and dopaminergic systems, but has no impact against monoamine oxidase A. Additionally, a notable cytotoxic effect was observed in SH-SY5Y and BV-2 cells at concentrations as low as 125 and 500 μg/mL (p < 0.05), respectively, LDH leakage suggesting apoptosis may occur at these concentrations, with necroptosis observed at higher ones. Despite the neurocytotoxic profile, these effects appear to be independent of radical stress, as the C. zacatechichi extract scavenged nitric oxide and superoxide radicals at concentrations as low as 62.5 μg/mL, significantly inhibiting also 5-lipoxygenase (IC50 = 72.60 ± 7.3 μg/mL; p < 0.05). Qualitative and quantitative analysis using HPLC-DAD-ESI(Ion Trap)MSn enabled the identification of 28 constituents, with 24 of them being previously unreported in this species. These include a series of dicaffeoylquinic, caffeoylpentoside, and feruloylquinic acids, along with 8 flavonols not previously known to occur in the species, mainly 3-O-monoglycosylated derivatives of quercetin, kaempferol, and isorhamnetin.

CONCLUSIONS

Our findings regarding the neuroglial toxicity elicited by C. zacatechichi emphasize the necessity for a thorough elucidation of the plant's toxicity profile. Additionally, evidence is provided that the aerial parts of the plant inhibit both acetylcholinesterase and tyrosinase, potentially linking its psychopharmacological effects to the cholinergic and dopaminergic systems, with an apparent contribution from specific phenolic constituents previously unknown to occur in the species. Collectively, our results lay the groundwork for a regulatory framework on the consumption of C. zacatechichi in recreational settings and contribute to elucidating previous contradictory findings regarding the mechanisms underlying the dream-inducing effects of the plant.

The ethnobotany, phytochemistry, and biological properties of genus Phagnalon (Asteraceae): a review

The genus Phagnalon Cass., included within the Asteraceae family, has a wide distribution, expanding from Macaronesia in the West to the Himalayas in the East, from S. France and N. Italy to Ethiopia and Arabian Peninsula. Various species of Phagnalon have been used in the popular medicine of several countries as medicinal herbs and food. This literature review, the first one of the Phagnalon genus, includes publications with the word 'Phagnalon', and considers the extracts and the single metabolites identified, characterized, and tested to evaluate their biological potential. The extracts and the secondary metabolites, have a varied application spectrum at a biological level, with antimicrobial, antioxidant, antidiabetic, antitumor, etc. properties having been reported. Unfortunately, in vitro tests have not always been accompanied by in vivo tests, and this is the major critical aspect that emerges from the study of the scientific aspects related to this genus.

Potential therapeutic natural products against Alzheimer's disease with Reference of Acetylcholinesterase

Alzheimer's disease (AD), is the most common type of dementia primarily affecting the later years of life. Its prevalence is likely to increase in any aging population and will be a major burden on healthcare system by the mid of the century. Despite scientific and technological breakthroughs in the last 50 years, that have expanded our understanding of the disease on a system, cellular and molecular level, therapies that could stop or slow the progression of the disease are still unavailable. The Food and Drug Administration (FDA), has approved acetylcholinesterase (AChE) inhibitors (donepezil, galantamine, tacrine and rivastigmine) and glutamate receptor antagonist (memantine) for the treatment of AD. In this review we summarize the studies reporting phytocompounds and extracts from medicinal plants that show AChE inhibitory activities and could be of potential benefit in AD. Future research directions are suggested and recommendations made to expand the use of medicinal plants and their formulations to prevent, mitigate and treat AD.

Leafy Stems of Phagnalon saxatile subsp. saxatile from Algeriaas a Source of Chlorogenic Acids and Flavonoids with Antioxidant Activity: Characterization and Quantification Using UPLC-DAD-ESI-MSn

Phagnalon saxatile subsp. saxatile is a wild species widespread in Algeria which is utilized for medicinal purposes as analgesic and anticholesterolemic. However, information is still scarce regarding its phytochemical content. The objective of this study was to identify and quantify the phenolic compounds from different extracts of its leafy stems. For this purpose, the effects of four extracting solvents were investigated on the content of phenolic compounds and the antioxidant activity of this plant. The extracts prepared with polar solvents (methanol and water) contained higher amounts of phenolic compounds and showed better antioxidant activity than the extracts with apolar solvents (hexane, dichloromethane). The methanolic extract, richest in total phenolic and total flavonoid, had significant antioxidant activity as regarded by DPPH° scavenging capacity (IC50 of 5.5 µg/mL), ABTS+° scavenging capacity (IC50 of 63.8 µg/mL) and inhibition of oxidation of linoleic acid (IC50 of 22.7 µg/mL), when compared to synthetic antioxidants. Chlorogenic acids and several flavonoids were identified and quantified by UPLC-DAD-MSn. The di-O-caffeoylquinic acids isomers were the most concentrated phenolics (25.4 mg/g DW) in the methanolic extract.

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.

Nutraceutical Potential of Phenolics from 'Brava' and 'Mansa' Extra-Virgin Olive Oils on the Inhibition of Enzymes Associated to Neurodegenerative Disorders in Comparison with Those of 'Picual' and 'Cornicabra'

The increasing interest in the Mediterranean diet is based on the protective effects against several diseases, including neurodegenerative disorders. Polyphenol-rich functional foods have been proposed to be unique supplementary and nutraceutical treatments for these disorders. Extra-virgin olive oils (EVOOs) obtained from 'Brava' and 'Mansa', varieties recently identified from Galicia (northwestern Spain), were selected for in vitro screening to evaluate their capacity to inhibit key enzymes involved in Alzheimer's disease (AD) (acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and 5-lipoxygenase (5-LOX)), major depressive disorder (MDD) and Parkinson's disease (PD) (monoamine oxidases: hMAO-A and hMAO-B respectively). 'Brava' oil exhibited the best inhibitory activity against all enzymes, when they are compared to 'Mansa' oil: BuChE (IC50 = 245 ± 5 and 591 ± 23 mg·mL-1), 5-LOX (IC50 = 45 ± 7 and 106 ± 14 mg·mL-1), hMAO-A (IC50 = 30 ± 1 and 72 ± 10 mg·mL-1) and hMAO-B (IC50 = 191 ± 8 and 208 ± 14 mg·mL-1), respectively. The inhibitory capacity of the phenolic extracts could be associated with the content of secoiridoids, lignans and phenolic acids.

A new 2-alkylhydroquinone glucoside from Phagnalon saxatile (L.) Cass

A new 2-alkylhydroquinone glucoside, 1-O-β-d-glucopyranosyl-1,4-dihydroxy-2-((E) 2-oxo-3-butenyl)benzene (1), in addition to nine known compounds were isolated from the aerial parts of Phagnalon saxatile (L.) Cass. (Asteraceae). Their structures were identified based on spectroscopic methods including 1D and 2D NMR, mass spectrometry (HR-ESI-MS), UV spectral analyses and by comparison with literature data. The cytotoxic activity of three isolated compounds (1-3) was evaluated against fibrosarcoma (HT1080), human lung cancer (A549) and breast cancer (MCF7) cell lines.

Natural products against Alzheimer's disease: Pharmaco-therapeutics and biotechnological interventions

Alzheimer's disease (AD) is a severe, chronic and progressive neurodegenerative disease associated with memory and cognition impairment ultimately leading to death. It is the commonest reason of dementia in elderly populations mostly affecting beyond the age of 65. The pathogenesis is indicated by accumulation of the amyloid-beta (Aβ) plaques and neurofibrillary tangles (NFT) in brain tissues and hyperphosphorylation of tau protein in neurons. The main cause is considered to be the formation of reactive oxygen species (ROS) due to oxidative stress. The current treatment provides only symptomatic relief by offering temporary palliative therapy which declines the rate of cognitive impairment associated with AD. Inhibition of the enzyme acetylcholinesterase (AChE) is considered as one of the major therapeutic strategies offering only symptomatic relief and moderate disease-modifying effect. Other non-cholinergic therapeutic approaches include antioxidant and vitamin therapy, stem cell therapy, hormonal therapy, use of antihypertensive or lipid-lowering medications and selective phosphodiesterase (PDE) inhibitors, inhibition of β-secretase and γ-secretase and Aβ aggregation, inhibition of tau hyperphosphorylation and intracellular NFT, use of nonsteroidal anti-inflammatory drugs (NSAIDs), transition metal chelators, insulin resistance drugs, etanercept, brain-derived neurotrophic factor (BDNF) etc. Medicinal plants have been reported for possible anti-AD activity in a number of preclinical and clinical trials. Ethnobotany, being popular in China and in the Far East and possibly less emphasized in Europe, plays a substantial role in the discovery of anti-AD agents from botanicals. Chinese Material Medica (CMM) involving Chinese medicinal plants has been used traditionally in China in the treatment of AD. Ayurveda has already provided numerous lead compounds in drug discovery and many of these are also undergoing clinical investigations. A number of medicinal plants either in their crude forms or as isolated compounds have exhibited to reduce the pathological features associated with AD. In this present review, an attempt has been made to elucidate the molecular mode of action of various plant extracts, phytochemicals and traditional herbal formulations investigated against AD as reported in various preclinical and clinical tests. Herbal synergism often found in polyherbal formulations were found effective to combat disease heterogeneity as found in complex pathogenesis of AD. Finally a note has been added to describe biotechnological improvement, genetic and genomic resources and mathematical and statistical techniques for empirical model building associated with anti-AD plant secondary metabolites and their source botanicals.

Rosemary tea consumption results to anxiolytic- and anti-depressant-like behavior of adult male mice and inhibits all cerebral area and liver cholinesterase activity; phytochemical investigation and in silico studies

Our aim was to investigate the possible effects of regular drinking of Rosmarinus officinalis L. leaf infusion on behavior and on AChE activity of mice. Rosemary tea (2% w/w) phytochemical profile was investigated through LC/DAD/ESI-MS(n). Adult male mice were randomly divided into two groups: "Rosemary-treated" that received orally the rosemary tea for 4weeks and "control" that received drinking water. The effects of regular drinking of rosemary tea on behavioral parameters were assessed by passive avoidance, elevated plus maze and forced swimming tests. Moreover, its effects on cerebral and liver cholinesterase (ChE) isoforms activity were examined colorimetricaly. Phytochemical analysis revealed the presence of diterpenes, flavonoids and hydroxycinnamic derivatives in rosemary tea; the major compounds were quantitatively determined. Its consumption rigorously affected anxiety/fear and depression-like behavior of mice, though memory/learning was unaffected. ChE isoforms activity was significantly decreased in brain and liver of "rosemary treated" mice. In order to explain the tissue ChE inhibition, principal component analysis, pharmacophore alignment and molecular docking were used to explore a possible relationship between main identified compounds of rosemary tea, i.e. rosmarinic acid, luteolin-7-O-glucuronide, caffeic acid and known AChE inhibitors. Results revealed potential common pharmacophores of the phenolic components with the inhibitors. Our findings suggest that rosemary tea administration exerts anxiolytic and antidepressant effects on mice and inhibits ChE activity; its main phytochemicals may function in a similar way as inhibitors.

Protective effects of caffeic acid against hypothalamic neuropeptides alterations induced by malathion in rat

Exposure to pesticides is suspected to cause human health problems. Our study aimed to evaluate preventive effects of caffeic acid (3,4-dihydroxycinnamic acid) in the hypothalamus against malathion-induced neuropeptides gene expression alterations. Malathion at 100 mg/kg was administered intragastrically to rats alone or in combination with caffeic acid at 100 mg/kg during 4 weeks. A molecular expression of hypothalamic neuropeptides and plasmatic cholinesterase activity was investigated. Furthermore, we used in silico analysis, known as computational docking, to highlight the nature of acetylcholinesterase-malathion/caffeic acid interactions. Our findings showed differences in the responses and indicate that caffeic acid reversed malathion-induced decrease in corticotropin-releasing hormone mRNA but not brain-derived neurotrophic factor which presented an increased tendency. We suggest that caffeic acid can interact with acetylcholinesterase as the primary target of organophosphorus compounds. Results predict that caffeic acid can block partly the acetylcholinesterase gorge entrance via π-π stacking interaction with Tyr 124 and Trp 286 residues of the peripheral site leading to its stricture. Under this condition, we suggested that acetylcholine trafficking toward the catalytic site is ameliorated compared to malaoxon according to their sizes.

Antioxidant activity profiling by spectrophotometric methods of aqueous methanolic extracts of Helichrysum stoechas subsp. rupestre and Phagnalon saxatile subsp. saxatile

AIM

The aqueous methanolic extracts of two plants from Algeria, Helichrysum stoechas subsp. rupestre and Phagnalon saxatile subsp. saxatile, were investigated for their antioxidant activity.

METHOD

Total phenolics, flavonoids, and tannins were determined by spectrophotometric techniques. In vitro antioxidant and radical scavenging profiling was determined by spectrophotometric methods, through: Total antioxidant capacity, and radical scavenging effects by the DPPH and ABTS methods, reducing and chelating power, and blanching inhibition of the β-carotene.

RESULTS

All of the extracts showed interesting antioxidant and radical scavenging activity. The highest contents in phenolics, tannins, and the highest total antioxidant capacity as gallic acid equivalents of 97.5 ± 0.33 mg GAE/g DW was obtained for the flowers of H. stoechas subsp. rupestre extract in the phosphomolybdenum assay. An extract of the leafy stems of P. saxatile subsp. saxatile revealed the highest content of flavonoids, and the highest antioxidant activity by the radical scavenging and β-carotene assays when compared with standards. The best activity was by the scavenging radical DPPH with an IC50 value of 5.65 ± 0.10 μg·mL(-1).

CONCLUSION

The studied medicinal plants could provide scientific evidence for some traditional uses in the treatment of diseases related to the production of reactive oxygen species (ROS) and oxidative stress.

Flavonoids with M1 muscarinic acetylcholine receptor binding activity

Muscarinic acetylcholine receptor-active compounds have potential for the treatment of Alzheimer’s disease. In this study, a series of natural and synthetic flavones and flavonols was assayed in vitro for their ability to inhibit radioligand binding at human cloned M₁ muscarinic receptors. Several compounds were found to possess competitive binding affinity (K_i = 40–110 µM), comparable to that of acetylcholine (K_i = 59 µM). Despite the fact that these compounds lack a positively-charged ammonium group under physiological conditions, molecular modelling studies suggested that they bind to the orthosteric site of the receptor, mainly through non-polar interactions.

Amelioration of intracerebroventricular streptozotocin induced cognitive impairment by Evolvulus alsinoides in rats: in vitro and in vivo evidence

Evolvulus alsinoides, also known as Shankpushapi, is a commonly used traditional medicine for enhancing memory. We evaluated the in vitro free radical scavenging and enzymes [acetylcholinesterase, butyrylcholinestrase, glycogen synthase kinase-3-β (GSK-3-β), rho kinase (ROCK II), prolyl endopeptidase (PEP), catechol-O-methyl transferase (COMT) and lipoxygenase (LOX)] inhibitory activities of aqueous and hydro-alcoholic extracts of E. alsinoides. Hydro-alcoholic extract of E. alsinoides demonstrated more free radical scavenging activity as compared to aqueous extract. Hydro-alcoholic extract also showed higher cholinesterase, GSK-3-β, ROCK II, PEP, COMT and LOX enzyme inhibitory activities as compared to aqueous extract. Phytochemical analysis revealed more flavanoids in hydro-alcoholic extract as compared to aqueous extract but no significant difference in phenolic content of the two extracts was observed. Based on in vitro data, hydro-alcoholic extract (100, 300 and 500mg/kg, p.o.) was selected for in vivo study in intracerebroventricularly injected streptozotocin (STZ) induced cognitive impairment in male Wistar rats. Elevated plus maze, passive avoidance and Morris water maze were used for assessment of cognitive function on 14th, 21st and 28th day after STZ injection. Oxidative stress parameters (malondialdehyde, reduced glutathione, nitric oxide levels and superoxide dismutase activity), cholinergic dysfunction and rho kinase (ROCK II) expression were studied in cerebral cortex and hippocampus of rat brain at the end of the study. Hydro-alcoholic extract of E. alsinoides dose dependently prevented STZ induced cognitive impairment by reducing the oxidative stress, improving cholinergic function and preventing the increase in rho kinase expression. The results suggest an anti-Alzheimer potential of hydro-alcoholic extract of E. alsinoides.

Antioxidant and Anti-cholinesterase Activity of Globularia meridionalis Extracts and Isolated Constituents

The antioxidant and anti-cholinesterase properties of Globularia meridional (Podp.) O. Schwarz (Globulariaceae) were investigated. G. meridionalis aerial parts and roots were extracted with methanol, and the total extract successively partitioned with n-hexane. The methanol fraction of the roots showed the highest antioxidant activity with IC50 values of 8.0 and 2.1 μg/mL in the DPPH and β-carotene bleaching tests, respectively. From this fraction, three flavonoids, namely pectolinarigenin 7- O-β-glucoside, apigenin 7- O-β-glucoside and luteolin, and two phenylethanoids, namely acteoside and isoacteoside, were isolated. Potential anti-cholinesterase effects were assessed through the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes inhibition assay. The n-hexane fraction of the roots exhibited the highest activity against both AChE and BChE with IC50 values of 65.5 and 70.4 μg/mL, respectively.

Antioxidant and anti-inflammatory properties of Cardiospermum halicacabum and its reference compounds ex vivo and in vivo

AIMS OF THE STUDY

Cardiospermum halicacabum (CH) has been used in Chinese medicine for a long time. However, its fingerprint chromatogram, antioxidant, anti-inflammatory effects and mechanism are still needed to be explored. Therefore, the aims of this study investigated the antioxidant and anti-inflammatory effects of CH extracts and its reference compounds ex vivo and in vivo.

MATERIALS AND METHODS

In HPLC analysis, the fingerprint chromatogram of ethanolic extract of CH (ECH) was established. The effects of ACH (aqueous extract of CH) and ECH extracts were assessed for the antioxidant and LPS-induced NO production in RAW264.7 cells. In vivo anti-inflammatory activities of ECH were evaluated in mouse paw edema induced by λ-carrageenan (Carr). We investigate the anti-inflammatory mechanism of ECH via studies of the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the liver and the levels of malondialdehyde (MDA) and nitrite oxide (NO) in the edema paw. Serum NO and TNF-α were also measured.

RESULTS

ECH had better antioxidant activity than that of ACH. In the anti-inflammatory test, ECH inhibited the development of paw edema induced by Carr and increased the activities of CAT, SOD and GPx in the liver tissue. ECH also decreased the level of NO in edematous paw tissue and in serum level, and diminished the level of serum TNF-α at the fifth hour after Carr injection.

CONCLUSIONS

ECH exerts anti-inflammatory effects by suppressing TNF-α and NO. The anti-inflammatory mechanism of ECH might be related to the decrement of the level of MDA in the edema paw via increasing the activities of CAT, SOD and GPx in the liver. The results showed that ECH might serve as a natural antioxidant and anti-inflammatory agent.

Natural products as a source of Alzheimer's drug leads

This review focuses on recent developments in the use of natural products as therapeutics for Alzheimer's disease. The compounds span a diverse array of structural classes and are organized according to their mechanism of action, with the focus primarily on the major hypotheses. Overall, the review discusses more than 180 compounds and summarizes 400 references.