Screening and identification of neuroprotective compounds relevant to Alzheimer׳s disease from medicinal plants of S. Tomé e Príncipe

The Neuroprotective Flavonoids Sterubin and Fisetin Maintain Mitochondrial Health under Oxytotic/Ferroptotic Stress and Improve Bioenergetic Efficiency in HT22 Neuronal Cells

The global increase in the aging population has led to a rise in many age-related diseases with continuing unmet therapeutic needs. Research into the molecular mechanisms underlying both aging and neurodegeneration has identified promising therapeutic targets, such as the oxytosis/ferroptosis cell death pathway, in which mitochondrial dysfunction plays a critical role. This study focused on sterubin and fisetin, two flavonoids from the natural pharmacopeia previously identified as strong inhibitors of the oxytosis/ferroptosis pathway. Here, we investigated the effects of the compounds on the mitochondrial physiology in HT22 hippocampal nerve cells under oxytotic/ferroptotic stress. We show that the compounds can restore mitochondrial homeostasis at the level of redox regulation, calcium uptake, biogenesis, fusion/fission dynamics, and modulation of respiration, leading to the enhancement of bioenergetic efficiency. However, mitochondria are not required for the neuroprotective effects of sterubin and fisetin, highlighting their diverse homeostatic impacts. Sterubin and fisetin, thus, provide opportunities to expand drug development strategies for anti-oxytotic/ferroptotic agents and offer new perspectives on the intricate interplay between mitochondrial function, cellular stress, and the pathophysiology of aging and age-related neurodegenerative disorders.

Inubritantrimers A-D: Trimerized Sesquiterpenoid [4 + 2] Adducts Featuring a Distinctive Spiro-Polycyclic Scaffold from Inula britannica

Inubritantrimer A (1), a trace trimerized sesquiterpenoid [4 + 2] adduct featuring an unusual exo-exo type spiro-polycyclic scaffold, together with three new endo-exo [4 + 2] adducts, inubritantrimers B-D (2-4), were discovered from the flowers of Inula britannica. Their structures were elucidated using 1D/2D NMR, X-ray diffraction, and ECD approaches. 1 is characterized as a novel exo-exo trimer, synthesized biogenetically from three sesquiterpenoid monomers, featuring a unique linkage of C-11/C-1', C-13/C-3' and C-13'/C-3″, C-11'/C-1″ through a two-step exo [4 + 2] cycloaddition process. Compounds 1-4 exhibited modest cytotoxicity against breast cancer cells with IC50 values in the range of 5.84-12.01 μM.

The Neuroprotective Effect of Isotetrandrine on Parkinson's Disease via Anti-Inflammation and Antiapoptosis In Vitro and In Vivo

Parkinson's disease (PD) is one of the most influential diseases in the world, and the current medication only can relieve the clinical symptoms but not slow the progression of PD. Therefore, we intend to examine the neuroprotective activity of plant-derived compound isotetrandrine (ITD) in vitro and in vivo. In vitro, cells were cotreated with ITD and LPS to detect the inflammatory-related protein and mRNA. In vivo, zebrafish were pretreated with ITD and inhibitors prior to 6-OHDA treatment. Then, the behavior was monitored at 5 dpf. Our result showed ITD inhibited LPS-induced upregulation of iNOS, COX-2 protein expression, and iL-6, inos, cox-2, and cd11b mRNA expression in BV2 cells. The data in zebrafish also demonstrated a significant improvement of ITD on the 6-OHDA-induced locomotor deficiency. ITD also improved 6-OHDA-induced apoptosis in zebrafish PD. We also pharmacologically validated the mechanism with three inhibitors, including LY294002, PI3K inhibitor; LY32141996, ERK inhibitor, SnPP, and HO-1 inhibitors. All of these inhibitors could abolish the neuroprotective effect of ITD partially in locomotor activity. Besides, the molecular level also showed the same trend. Treatment of these inhibitors could significantly abolish ITD-induced antineuroinflammatory and antioxidative stress effects in zebrafish PD. Our study showed ITD possessed a neuroprotective activity in zebrafish PD. The mRNA level also supported our arguments. The neuroprotection of ITD might be through antineuroinflammation and antiapoptosis pathways via PI3K, ERK, and HO-1.

Exploration of essential oil from Psychotria poeppigiana as an anti-hyperalgesic and anti-acetylcholinesterase agent: Chemical composition, biological activity and molecular docking

ETHNOPHARMACOLOGICAL RELEVANCE

Leaves from Psychotria poeppigiana Müll. Arg. (accepted as Palicourea tomentosa (Aubl.) Borhidi), Rubiaceae, has traditionally been used in medicine for treatments of inflammation and pain; Synonymously, Cephaelis elata for the treatment of dementia; However, few scientific studies have been evidence demonstrating this activity.

AIM OF THE STUDY

The aim of this study was to investigate the chemical composition of P. poeppigiana essential oil obtained from leaves (EOPP) and its antioxidant, anti-inflammatory and acetylcholinesterase (AChE) activities. Molecular docking simulations were carried out with the main constituents.

MATERIALS AND METHODS

EOPP (hydrodistillation) was analysed by gas chromatography-mass spectrometry (GC-MS). The fractionation of EOPP afforded germacrene D and bicyclogermacrene. The antioxidant activity of EOPP was determined by MDA assay. The inflammatory parameters were evaluated using CFA model (with paw edema, mechanical, thermal hyperalgesia, MPO and NAG) in EOPP (30, 100 and 300 mg/kg), germacrene D and bicyclogermacrene (30 mg/kg). The AChE inhibition was evaluated in rat brain structures and molecular docking simulations were carried out using Autodock v.4.3.2.

RESULTS

GC-MS analysis identified 19 compounds, and the major compounds were germacrene D (29.38%) and bicyclogermacrene (25.21%). EOPP exhibited high antioxidant capacity (IC₅₀ = 12.78 ± 1.36 μg/mL). All the tested doses of EOPP and both major constituents significantly inhibited cold and mechanical hyperalgesia and significantly blocked the increase in MPO activity 24 h after the CFA injection. There was significant AChE inhibition by EOPP and germacrene D in the cerebral cortex and hippocampus (>50%). Enzyme-ligand molecular modelling showed that the major constituents of EOPP interacted differently with AChE.

CONCLUSIONS

The chemical compounds of the essential oil from the leaves of P. poeppigiana is based mainly on terpenes, the sesquiterpenes germacrene D (29.38%) and bicyclogermacrene (25.21%) being the major compounds. EOPP presented antioxidant, anti-inflammatory and anti-acetylcholinesterase (AChE) activities. Besides, enzyme-ligand molecular modelling showed the EOPP may act as an anti-hyperalgesic and AChE inhibitory agent. Taken together, these results might be in accordance with if folk use for pain- and inflammation-related symptoms.

Sesquiterpenoids from Inula britannica and Their Potential Effects against Triple-Negative Breast Cancer Cells

Flowers of Inula britannica commercially serve as pharmaceutical herbs in the manufacturing of medicinal products. In the current study, sesquiterpenoids of I. britannica flowers’ extract and their potential effects against triple-negative breast cancer (TNBC) cells were investigated. Eight structurally diverse sesquiterpenoids, including one sesquiterpenoid dimer (1) and seven sesquiterpenoid monomers (2−8) were isolated from this source. The structures of all compounds were elucidated by 1D/2D NMR data, and their absolute configurations were discerned by single crystal X-ray diffraction. All of the compounds were tested for their potential effects against TNBC. Specifically, 5 displayed strong antiproliferative potency against TNBC cells with a high selective index (SI) on MCF-7 cells (SI > 4 of IC50 on MDA-MB-468/IC50 on MCF-7), and dimer 1 (IC50 = 8.82 ± 0.85 μM) showed better antiproliferative potency against MCF-7 cells than the other monomers did (2−8) (IC50 > 20 μM). To our best knowledge, compound 5 is the first sesquiterpenoid targeting TNBC cells.

Imidazolylacetophenone oxime-based multifunctional neuroprotective agents: Discovery and structure-activity relationships

Alzheimer's disease (AD) possesses a complex pathogenetic mechanism. Nowadays, multitarget agents are considered to have potential in effectively treating AD via triggering molecules in functionally complementary pathways at the same time. Here, based on the screening (∼1400 compounds) against neuroinflammation, an imidazolylacetophenone oxime ether (IOE) was discovered as a novel hit. In order to obtain SARs, a series of imidazolylacetophenone oxime derivatives were constructed, and their C=N bonds were confirmed as the Z configuration by single crystals. These derivatives exhibited potential multifunctional neuroprotective effects including anti-neuroinflammatory, antioxidative damage, metal-chelating, inhibition of acetylcholinesterase (AChE) properties. Among these derivatives, compound 12i displayed the most potent inhibitory activity against nitric oxide (NO) production with EC₅₀ value of 0.57 μM 12i can dose-dependently suppress the expression of iNOS and COX-2 but not change the expression of HO-1 protein. Moreover, 12i exhibited evidently neuroprotective effects on H₂O₂-induced PC12 cells damage and ferroptosis without cytotoxicity at 10 μM, as well as selectively metal chelating properties via chelating Cu²⁺. In addition, 12i showed a mixed-type inhibitory effect on AChE in vitro. The structure-activity relationships (SARs) analysis indicated that dioxolane groups on benzene ring and rigid oxime ester can improve the activity. Parallel artificial membrane permeation assay (PAMPA) also verified that 12i can overcome the blood-brain barrier (BBB). Overall, this is the first report on imidazolylacetophenone oxime-based multifunctional neuroprotective effects, suggesting that this type of compounds might be novel multifunctional agents against AD.

Antimycobacterial Activity of Alkaloids and Extracts from Tabernaemontana alba and T. arborea

Tuberculosis is the main cause of death from a single infectious agent. Globally, according to the World Health Organization, in 2018, there were an estimated 1.2 million tuberculosis deaths. Moreover, there is a continuous appearance of drug-resistant strains. Thus, development of new antituberculosis medicines should receive high priority. Plant-derived natural products are promising candidates for this purpose. We therefore screened alkaloid extracts obtained from the root and stem barks of the Mexican Apocynaceae species Tabernaemontana alba and Tabernaemontana arborea, as well as the pure alkaloids ibogaine, voacangine, and voacamine, tested for activity against Mycobacterium tuberculosis H37Rv and cytotoxicity to mammalian Vero cells using the resazurin microtiter and the MTT assays, respectively. The extracts were analyzed by GC-MS and HPLC-UV. T. arborea root bark alkaloid extract showed the highest activity against M. tuberculosis (MIC100 = 7.8 µg/mL) of the four extracts tested. HPLC suggested that voacangine and voacamine were the major components. The latter was isolated by column chromatography, and its chemical structure was elucidated by 1H and 13C NMR, and MS. Unambiguous assignation was performed by HSQC, HMBC, and NOESY experiments. Voacamine is a dimeric bis-indole-type alkaloid and is 15 times more potent than the monomeric ibogan-type alkaloids ibogaine and voacangine (MIC100 = 15.6, 250.0, and 250.0 µg/mL, respectively). However, all of these compounds showed cytotoxicity to Vero cells, with a poor selectivity index of 1.00, 0.16, and 1.42, respectively. This is the first report of voacamine activity against M. tuberculosis.

Chemical characterization and multifunctional neuroprotective effects of sesquiterpenoid-enriched Inula britannica flowers extract

Dried flowers of Inula britannica commercially serve as pharmaceutical/nutraceutical herbs in the manufacture of medicinal products and functional tea that has been reported to possess extensive biological property. However, the neuroprotective constituents in I. britannica flowers are not known. In the current study, phytochemicals of sesquiterpenoid-enriched I. britannica flowers extract and their potential multifunctional neuroprotective effects were investigated. Nineteen structurally diverse sesquiterpenoids, including two new sesquiterpenoid dimers, namely, inubritanolides A and B (1, 2), and four new sesquiterpenoid monomers (3-6), namely, 1-O-acetyl-6-O-chloracetylbritannilactone (3), 6-methoxybritannilactone (4), 1-hydroxy-10β-methoxy-4αH-1,10-secoeudesma-5(6),11(13)-dien-12,8β-olide (5) and 1-hydroxy-4αH-1,10-secoeudesma-5(6),10(14),11(13)-trien-12,8β-olide (6), as well as 13 known congeners (7-19) were isolated from this source. The structures of compounds 1-6 were elucidated by 1D- and 2D- NMR and HR-ESI-MS data, and their absolute configurations were discerned by electronic circular dichroism (ECD) data analysis and single crystal X-ray diffraction. Interestingly, inubritannolide A (1) is a new type [4 + 2] Diels-Alder dimer featuring a hepta-membered cycloether skeleton. Most of the compounds showed potential multifunctional neuroprotective effects, including antioxidative, anti-neuroinflammatory, and microglial polarization properties. Specifically, 1 and 6 displayed slight strong neuroprotective potency against different types of neuronal cells mediated by various inducers including H₂O₂, 6-hydroxydopamine (6-OHDA), and lipopolysaccharide (LPS). Overall, this is the first report on multifunctional neuroprotective effects of sesquiterpenoid-enriched I. britannica flowers extract, which supports its potential pharmaceutical/nutraceutical application in neurodegenerative diseases.

The search for anti-oxytotic/ferroptotic compounds in the plant world

Oxytosis/ferroptosis is a form of non-apoptotic regulated cell death characterized by glutathione (GSH) depletion and dysregulated production of mitochondrial ROS that results in lethal lipid peroxidation. As the significance of oxytosis/ferroptosis to age-associated human diseases is now beginning to be appreciated, the development of innovative approaches to identify novel therapeutics that target the oxytosis/ferroptosis pathway could not be more timely. Due to their sessile nature, plants are exposed to a variety of stresses that trigger physiological changes similar to those found in oxytosis/ferroptosis. As such, they have evolved a rich array of chemical strategies to deal with those challenging conditions. This review details a drug discovery approach for identifying potent inhibitors of oxytosis/ferroptosis from plants for the treatment of Alzheimer's disease and related dementias, thereby highlighting the tremendous potential of plant-based research for developing new medicines while simultaneously being a catalyst for sustainability.

Natural products targeting mitochondria: emerging therapeutics for age-associated neurological disorders

Mitochondria are the primary source of energy production in the brain thereby supporting most of its activity. However, mitochondria become inefficient and dysfunctional with age and to a greater extent in neurological disorders. Thus, mitochondria represent an emerging drug target for many age-associated neurological disorders. This review summarizes recent advances (covering from 2010 to May 2020) in the use of natural products from plant, animal, and microbial sources as potential neuroprotective agents to restore mitochondrial function. Natural products from diverse classes of chemical structures are discussed and organized according to their mechanism of action on mitochondria in terms of modulation of biogenesis, dynamics, bioenergetics, calcium homeostasis, and membrane potential, as well as inhibition of the oxytosis/ferroptosis pathway. This analysis emphasizes the significant value of natural products for mitochondrial pharmacology as well as the opportunities and challenges for the discovery and development of future neurotherapeutics.

Development and Application of a Chemical Probe Based on a Neuroprotective Flavonoid Hybrid for Target Identification Using Activity-Based Protein Profiling

Alzheimer's disease (AD) is the most common form of dementia, and up to now, there are no disease-modifying drugs available. Natural product hybrids based on the flavonoid taxifolin and phenolic acids have shown a promising pleiotropic neuroprotective profile in cell culture assays and even disease-modifying effects in vivo. However, the detailed mechanisms of action remain unclear. To elucidate the distinct intracellular targets of 7-O-esters of taxifolin, we present in this work the development and application of a chemical probe, 7-O-cinnamoyltaxifolin-alkyne, for target identification using activity-based protein profiling. 7-O-Cinnamoyltaxifolin-alkyne remained neuroprotective in all cell culture assays. Western blot analysis showed a comparable influence on the same intracellular pathways as that of the lead compound 7-O-cinnamoyltaxifolin, thereby confirming its suitability as a probe for target identification experiments. Affinity pulldown and MS analysis revealed adenine nucleotide translocase 1 (ANT-1) and sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA) as intracellular interaction partners of 7-O-cinnamoyltaxifolin-alkyne and thus of 7-O-esters of taxifolin.

Pharmacology of Herbal Sexual Enhancers: A Review of Psychiatric and Neurological Adverse Effects

Sexual enhancers increase sexual potency, sexual pleasure, or libido. Substances increasing libido alter the concentrations of specific neurotransmitters or sex hormones in the central nervous system. Interestingly, the same pathways are involved in the mechanisms underlying many psychiatric and neurological disorders, and adverse reactions associated with the use of aphrodisiacs are strongly expected. However, sexual enhancers of plant origin have gained popularity over recent years, as natural substances are often regarded as a safer alternative to modern medications and are easily acquired without prescription. We reviewed the psychiatric and neurological adverse effects associated with the consumption of herbal aphrodisiacs Areca catechu L., Argemone Mexicana L., Citrus aurantium L., Eurycoma longifolia Jack., Lepidium meyenii Walp., Mitragyna speciosa Korth., Panax ginseng C. A. Mey, Panax quinquefolius L., Pausinystalia johimbe (K. Schum.) Pierre ex Beille, Piper methysticum G. Forst., Ptychopetalum olacoides Benth., Sceletium tortuosum (L.) N. E. Brown, Turnera diffusa Willd. ex. Schult., Voacanga africana Stapf ex Scott-Elliot, and Withania somnifera (L.) Dunal. A literature search was conducted on the PubMed, Scopus, and Web of Science databases with the aim of identifying all the relevant articles published on the issue up to June 2020. Most of the selected sexual enhancers appeared to be safe at therapeutic doses, although mild to severe adverse effects may occur in cases of overdosing or self-medication with unstandardized products. Drug interactions are more concerning, considering that herbal aphrodisiacs are likely used together with other plant extracts and/or pharmaceuticals. However, few data are available on the side effects of several plants included in this review, and more clinical studies with controlled administrations should be conducted to address this issue.

Ethnobotanical Study Aimed at Investigating the Use of Medicinal Plants to Treat Nervous System Diseases in the Rif of Morocco

Objective

The aim of this study was to assess the knowledge and use of medicinal plants in the treatment of neurological diseases in the Rif region of northern Morocco.

Methods

An ethnobotanical survey was carried out in the Rif (northern Morocco) from 2016 to 2018. In order to gather information about indigenous medicinal plants and local ethnomedical knowledge, 625 local traditional herbalists and users of these plants were interviewed. The data were collected through semistructured interviews and group discussions, analyzed, and compared by quantitative ethnobotanical indices such as family importance value, relative frequency of citation, plant part value (PPV), fidelity level, and informant consensus factor (ICF) .

Results

Data were collected from 31 medicinal plant species belonging to 14 botanical families. Asteraceae and Lamiaceae were the most commonly reported medicinal plants, with 5 species each. Concerning the diseases treated, epilepsy problems have the highest ICF (0.99). The survey revealed that leaves were the most used part of the plants (PPV= 34.7%), and the most commonly used preparation was an infusion (41.6%).

Conclusion

There exists indigenous ethnomedical knowledge of medicinal plants in the Moroccan Rif to treat neurologic diseases. Based on our findings, we recommend that phytochemical and pharmacologic research be considered to discover potential treatments from these documented plants.

The Value of Herbarium Collections to the Discovery of Novel Treatments for Alzheimer's Disease, a Case Made With the Genus Eriodictyon

Plants, in particular those with a history in traditional medicine, hold enormous potential as sources of new therapies for dementias such as Alzheimer’s disease (AD). The largest collections of plants can be found in herbaria all over the world, but the value of these collections to AD drug discovery has been significantly neglected. As a proof of principle, we investigated the neuroprotective activity of herbarium specimens of Eriodictyon (yerba santa), a genus with a long history of usage by the indigenous tribes in California to treat respiratory and age-related complications. Dichloromethane extracts were prepared from leaves of 14 Eriodictyon taxa preserved in the SD Herbarium located at the San Diego Natural History Museum. The extracts were tested for neuroprotection in nerve cells against oxytosis and ferroptosis and for anti-inflammatory activity in brain microglial cells exposed to bacterial lipopolysaccharide. In parallel, the levels of the flavanones sterubin, eriodictyol and homoeriodictyol were measured by mass spectrometry. Several Eriodictyon species presented strong neuroprotective and anti-inflammatory activities. The protective properties of the extracts correlated with the amount of sterubin, but not with eriodictyol or homoeriodictyol, indicating that sterubin is the major active compound in these species. The occurrence of eriodictyol and homoeriodictyol may be predictive of the phylogenetic relationship between members in the genus Eriodictyon. The data offer insight into the traditional use of yerba santa across indigenous tribes in California, while demonstrating the value of herbarium collections for the discovery of novel therapeutic compounds for the treatment of neurodegenerative diseases.

Potential Therapeutic Approaches to Alzheimer's Disease By Bioinformatics, Cheminformatics And Predicted Adme-Tox Tools

BACKGROUND

Alzheimer's disease (AD) is considered a severe, irreversible and progressive neurodegenerative disorder. Currently, the pharmacological management of AD is based on a few clinically approved acethylcholinesterase (AChE) and N-methyl-D-aspartate (NMDA) receptor ligands, with unclear molecular mechanisms and severe side effects.

METHODS

Here, we reviewed the most recent bioinformatics, cheminformatics (SAR, drug design, molecular docking, friendly databases, ADME-Tox) and experimental data on relevant structurebiological activity relationships and molecular mechanisms of some natural and synthetic compounds with possible anti-AD effects (inhibitors of AChE, NMDA receptors, beta-secretase, amyloid beta (Aβ), redox metals) or acting on multiple AD targets at once. We considered: (i) in silico supported by experimental studies regarding the pharmacological potential of natural compounds as resveratrol, natural alkaloids, flavonoids isolated from various plants and donepezil, galantamine, rivastagmine and memantine derivatives, (ii) the most important pharmacokinetic descriptors of natural compounds in comparison with donepezil, memantine and galantamine.

RESULTS

In silico and experimental methods applied to synthetic compounds led to the identification of new AChE inhibitors, NMDA antagonists, multipotent hybrids targeting different AD processes and metal-organic compounds acting as Aβ inhibitors. Natural compounds appear as multipotent agents, acting on several AD pathways: cholinesterases, NMDA receptors, secretases or Aβ, but their efficiency in vivo and their correct dosage should be determined.

CONCLUSION

Bioinformatics, cheminformatics and ADME-Tox methods can be very helpful in the quest for an effective anti-AD treatment, allowing the identification of novel drugs, enhancing the druggability of molecular targets and providing a deeper understanding of AD pathological mechanisms.

7-O-Esters of taxifolin with pronounced and overadditive effects in neuroprotection, anti-neuroinflammation, and amelioration of short-term memory impairment in vivo

Alzheimer's disease (AD) is a multifactorial disease and the most common form of dementia. There are no treatments to cure, prevent or slow down the progression of the disease. Natural products hold considerable interest for the development of preventive neuroprotectants to treat neurodegenerative disorders like AD, due to their low toxicity and general beneficial effects on human health with their anti-inflammatory and antioxidant features. In this work we describe regioselective synthesis of 7-O-ester hybrids of the flavonoid taxifolin with the phenolic acids cinnamic and ferulic acid, namely 7-O-cinnamoyltaxifolin and 7-O-feruloyltaxifolin. The compounds show pronounced overadditive neuroprotective effects against oxytosis, ferroptosis and ATP depletion in the murine hippocampal neuron HT22 cell model. Furthermore, 7-O-cinnamoyltaxifolin and 7-O-feruloyltaxifolin reduced LPS-induced neuroinflammation in BV-2 microglia cells as assessed by effects on the levels of NO, IL6 and TNFα. In all in vitro assays the 7-O-esters of taxifolin and ferulic or cinnamic acid showed strong overadditive activity, significantly exceeding the effects of the individual components and the equimolar mixtures thereof, which were almost inactive in all of the assays at the tested concentrations. In vivo studies confirmed this overadditive effect. Treatment of an AD mouse model based on the injection of oligomerized Aβ_25-35 peptide into the brain to cause neurotoxicity and subsequently memory deficits with 7-O-cinnamoyltaxifolin or 7-O-feruloyltaxifolin resulted in improved performance in an assay for short-term memory as compared to vehicle and mice treated with the respective equimolar mixtures. These results highlight the benefits of natural product hybrids as a novel compound class with potential use for drug discovery in neurodegenerative diseases due to their pharmacological profile that is distinct from the individual natural components.

Influence of lipid composition on the ability of liposome loaded voacamine to improve the reversion of doxorubicin resistant osteosarcoma cells

The plant alkaloid voacamine (VOA) displays many interesting pharmacological activities thus, considering its scarce solubility in water, its encapsulation into liposome formulations for its delivery is an important goal. Different cationic liposome formulations containing a phospholipid, cholesterol and one of two diasteromeric cationic surfactants resulted able to maintain a stable transmembrane difference in ammonium sulfate concentration and/or pH gradient and to accumulate VOA in their internal aqueous bulk. The fluidity of the lipid bilayer affects both the ability to maintain a stable imbalance of protons and/or ammonium ions across the membrane and the entrapment efficiency. It was shown that VOA loaded into liposomes is more efficient than the free alkaloid to revert resistance of osteosarcoma cells resistant to doxorubicin to an extent depending on their composition.

Optimization of Hyperglycemic Induction in Zebrafish and Evaluation of Its Blood Glucose Level and Metabolite Fingerprint Treated with Psychotria malayana Jack Leaf Extract

A standard protocol to develop type 1 diabetes in zebrafish is still uncertain due to unpredictable factors. In this study, an optimized protocol was developed and used to evaluate the anti-diabetic activity of Psychotria malayana leaf. The aims of this study were to develop a type 1 diabetic adult zebrafish model and to evaluate the anti-diabetic activity of the plant extract on the developed model. The ability of streptozotocin and alloxan at a different dose to elevate the blood glucose levels in zebrafish was evaluated. While the anti-diabetic activity of P. malayana aqueous extract was evaluated through analysis of blood glucose and LC-MS analysis fingerprinting. The results indicated that a single intraperitoneal injection of 300 mg/kg alloxan was the optimal dose to elevate the fasting blood glucose in zebrafish. Furthermore, the plant extract at 1, 2, and 3 g/kg significantly reduced blood glucose levels in the diabetic zebrafish. In addition, LC-MS-based fingerprinting indicated that 3 g/kg plant extract more effective than other doses. Phytosterols, sugar alcohols, sugar acid, free fatty acids, cyclitols, phenolics, and alkaloid were detected in the extract using GC-MS. In conclusion, P. malayana leaf aqueous extract showed anti-diabetic activity on the developed type 1 diabetic zebrafish model.

One bis-indole alkaloid-voacamine from Voacanga africana Stapf: biological activity evaluation of PTP1B in vitro utilizing enzymology method based on SPRi expriment

One known bis-indole alkaloid-voacamine was isolated from Voacanga africana Stapf and Surface Plasmon Resonance imaging (SPRi) exprement showed that this alkaloid could be combine with Protein Tyrosine Phosphatase1B (PTP1B). Then the PTP1B activity inhibition experiment display that the compound showed an outstanding promoting activity to PTP1B.

Regioselective synthesis of 7-O-esters of the flavonolignan silibinin and SARs lead to compounds with overadditive neuroprotective effects

A series of neuroprotective hybrid compounds was synthesized by conjugation of the flavonolignan silibinin with natural phenolic acids, such as ferulic, cinnamic and syringic acid. Selective 7-O-esterfication without protection groups was achieved by applying the respective acyl chlorides. Sixteen compounds were obtained and SARs were established by evaluating antioxidative properties in the physicochemical FRAP assay, as well as in a cell-based neuroprotection assay using murine hippocampal HT-22 cells. Despite weak activities in the FRAP assay, esters of the α,β-unsaturated acids showed pronounced overadditive effects at low concentrations greatly exceeding the effects of equimolar mixtures of silibinin and the respective acids in the neuroprotection assay. Cinnamic and ferulic acid esters (5a and 6a) also showed overadditive effects regarding inhibition of microglial activation, PC12 cell differentiation, in vitro ischemia as well as anti-aggregating abilities against Aβ42 peptide and τ protein. Remarkably, the esters of ferulic acid with silybin A and silybin B (11a and 11b) showed a moderate but significant difference in both neuroprotection and in their anti-aggregating capacities. The results demonstrate that non-toxic natural antioxidants can be regioselectively connected as esters with medium-term stability exhibiting very pronounced overadditive effects in a portfolio of biological assays.

Cassia obtusifolia seed ameliorates amyloid β-induced synaptic dysfunction through anti-inflammatory and Akt/GSK-3β pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Tea infused with the seed of Cassia obtusifolia has been traditionally used as an herbal remedy for liver, eye, and acute inflammatory diseases. Recent pharmacological reports have indicated that Cassiae semen has neuroprotective effects, attributable to its anti-inflammatory actions, in ischemic stroke and Parkinson's disease models.

AIM OF THE STUDY

Previously, the ethanol extract of C. obtusifolia seeds (COE) was reported to have memory enhancing properties. However, the effects of COE in an Alzheimer's disease (AD) model are currently unknown. In this study, we investigated the effect(s) of COE on aberrant synaptic plasticity and memory impairment induced by amyloid β (Aβ), a key toxic component found in the AD brain.

MATERIALS AND METHODS

To determine the effect of COE on Aβ-induced aberrant synaptic plasticity, we used acute mouse hippocampal slices and delivered theta burst stimulation to induce long-term potentiation (LTP). Western blots were used to detect Aβ- and/or COE-induced changes in signaling proteins. The novel object location recognition test was conducted to determine the effect of COE on Aβ-induced recognition memory impairment.

RESULTS

COE was found to ameliorate Aβ-induced LTP impairment in the acute hippocampal slices. Glycogen synthase kinase-3β (GSK-3β), a key molecule in LTP impairment, was activated by Aβ. However, this process was inhibited by COE via Akt signaling. Moreover, COE was found to attenuate Aβ-induced microglia, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX) activation. In the in vivo studies performed, COE ameliorated the Aβ-induced object recognition memory impairment.

CONCLUSION

These results suggest that COE exhibits neuroprotective activities against Aβ-induced brain disorders.

Alzheimer's Disease and Medicinal Plants: An Overview

Alzheimer's disease (AD) is progressive neurodegenerative disorder and identified as a major health concern globally. Individuals with AD and their care givers are affected in personal, emotional, financial, and social levels. Due to its significant impact and heavy burden on the individual, the patients' families, and society, it is highly needed to search for cost effective, long-time retention therapeutic targets. In recent decades, there are lots of research conducted the possible benefit of natural products and their active components on AD and other neurodegenerative disease, which are discussed here.

Medicinal plants: An invaluable, dwindling resource in sub-Saharan Africa

ETHNOPHARMACOLOGICAL RELEVANCE

The use of plant species for different therapeutic/medicinal purposes is well-entrenched in sub-Saharan Africa.

AIM OF THE REVIEW

To provide a critical and updated review of the enormous medicinal plant heritage in sub-Saharan Africa with regards to the abundance, importance, conservation status and potential means to help sustain their availability for future generations.

METHODS

A comprehensive literature search involving different online databases, books and theses were conducted in order to obtain, collate and synthesize available information on various fundamental aspects pertaining to African medicinal plants.

RESULTS

African biodiversity hotspots are endowed with a high level of endemic species with a significant portion possessing medicinal value. Apart from the extensive ethnobotanical uses of medicinal plants found in Africa, scientific validation of their biological potential such as antimicrobial, antioxidant, anti-inflammatory and anti-diabetic properties have been recognized. Together with the demand arising from their biological efficacies, other anthropogenic factors are exerting conservation strains of the wild population of these medicinal plants. Even though researchers have acknowledged the importance and value of conserving these medicinal plants, several challenges have hampered these efforts on the Continent as a whole.

CONCLUSIONS

The rich flora occurring in sub-Saharan Africa suggests enormous potential for discovery of new chemical entity with therapeutic value. However, concerted efforts focused on documenting the conservation status of African medicinal plants are pertinent. Application of different biotechnological techniques is needed to sustain these valuable botanical entities, especially to meet increasing pharmaceutical demand. Most importantly, increased public enlightenment and awareness may help eradicate the prejudice against cultivation of medicinal plants.

Herbs to curb cyclic nucleotide phosphodiesterase and their potential role in Alzheimer's disease

Cyclic nucleotides viz., cAMP/cGMP has been well known to play important role in cellular function and deficiency in their levels has been implicated in the pathogenesis of various neurodegenerative disorders including Alzheimer's disease (AD). Phosphodiesterases (PDE) are the enzymes involved in the metabolism of cyclic nucleotides and the inhibition of phosphodiesterases is considered to be viable strategy to restore the level of cyclic nucleotides and their functions in the brain. Various synthetic PDE inhibitors had been used clinically for various disorders and also suggested to be useful candidates for treating neurological disorders. However, side effects of these synthetic PDE inhibitors have limited their use in clinical practice. Natural plant extracts or their bio-active compounds are considered to be safe and are widely acceptable. During the last decade, many plant extracts or their bio-active compounds were tested pre-clinically for PDE inhibitory activity and are reported to be equally potent in inhibiting PDE's, as that of synthetic compounds. The present review is aimed to discuss the potential plant extract/compounds with PDE inhibitory activity and critically discuss their potential role in Alzheimer's disease.

Back to the future with phenotypic screening

There are no disease-modifying drugs for any old age associated neurodegenerative disease or stroke. This is at least in part due to the failure of drug developers to recognize that the vast majority of neurodegenerative diseases arise from a confluence of multiple toxic insults that accumulate during normal aging and interact with genetic and environmental risk factors. Thus, it is unlikely that the current single target approach based upon rare dominant mutations or even a few preselected targets is going to yield useful drugs for these conditions. Therefore, the identification of drug candidates for neurodegeneration should be based upon their efficacy in phenotypic screening assays that reflect the biology of the aging brain, not a single, preselected target. It is argued here that this approach to drug discovery is the most likely to produce safe and effective drugs for neurodegenerative diseases.