Anti-cholinesterases and memory improving effects of Vietnamese Xylia xylocarpa

Pharmacognostic characterization, wound healing and toxicity assessment of the stem bark of Xylia evansii Hutch (Leguminosae)

Xylia evansii is widely used in traditional medicine to stop bleeding gums and treat wounds. This study was undertaken to assess the wound healing activity and toxicity profile of the stem bark methanol extract of X. evansii (XES). Wound healing activity was determined by the dermal excision model in rats. The free radical scavenging capacity, antioxidant activity, total phenolic and flavonoid contents were evaluated by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, total antioxidant capacity (TAC), aluminum chloride colorimetric and Folin Ciocalteu methods respectively. Acute and sub-acute oral toxicity assessment was performed following the Organization for Economic Co-operation and Development guidelines. Significant (p < 0.05) dose-dependent wound healing effect, similar to that of 1 % silver sulphadiazine was elicit by the 10, 15 and 20 %w/w XES ointments. The highest effect was demonstrated by XES 20 %w/w which resulted in 98.3 % wound surface closure by day 9 of treatment (p < 0.0001). The total phenolic and flavonoid contents were determined to be 381.2 ± 12.57 mg/g gallic acid equivalent (GAE) and 460 ± 29.07 mg/g quercetin equivalent respectively. XES exhibited remarkable free radical scavenging effect (IC50 = 68.13 ± 1.87 μg/mL) and had a total antioxidant capacity of 279.2 ± 32.08 mg/g GAE. The LD50 of XES was estimated to be > 5000 mg/kg. In sub-acute toxicity, 28 days treatment with XES (250, 500, 1000 mg/kg body weight) did not result in any significant (p > 0.05) change in the body weight or weight of the heart, lung, spleen, liver and kidneys. The haematological and biochemical profiles of XES-treated rats were not significantly (p > 0.05) affected after 4-weeks treatment with XES, except for platelet count which increased significantly (p < 0.0001) in a non-dose-dependent manner. Histopathological examination did not reveal any toxic effect to liver cells, however at 1000 mg/kg XES, slight abnormalities were identified in the glomeruli. Microscopy of the powdered stem bark displayed calcium oxalate crystals, pitted vessels and lignified fibres. Tannins, flavonoids, coumarins, saponins, triterpenes and alkaloids were identified in the bark. This is the first report on the wound healing potential and safety profile of X. evansii, giving scientific credence to its use in traditional medicine.

Novel Anti-Acetylcholinesterase Effect of Euonymus laxiflorus Champ. Extracts via Experimental and In Silico Studies

Alzheimer's disease (AD) is the most common form of dementia, which is recorded as a global health issue. Natural acetylcholinesterase inhibitors (AChEIs) are considered a helpful therapy for the management of symptoms of patients with mild-to-moderate AD. This work aimed to investigate and characterize Euonymus laxiflorus Champ. (ELC) as a natural source of AChEIs compounds via in vitro and virtual studies. The screening parts used, including the leaves, heartwood, and trunk bark of ELC, revealed that the trunk bark extract possessed the highest activity, phenolics and flavonoid content. The in vitro anti-Alzheimer activity of ELC trunk bark was notably reclaimed for the first time with comparable effect (IC₅₀ = 0.332 mg/mL) as that of a commercial AChEI, berberine chloride (IC₅₀ = 0.314 mg/mL). Among various solvents, methanol was the most suitable to extract ELC trunk bark with the highest activity. Twenty-one secondary metabolites (1-21) were identified from ELC trunk bark extract, based on GCMS and UHPLC analyses. Of these, 10 volatile compounds were identified from this herbal extract for the first time. One phenolic (11) and seven flavonoid compounds (15-21) were also newly found in this herbal extract. Of the identified compounds, chlorogenic acid (11), epigallocatechin gallate (12), epicatechin (13), apigetrin (18), and quercetin (20) were major compounds with a significant content of 395.8-2481.5 μg/g of dried extract. According to docking-based simulation, compounds (11-19, and 21) demonstrated more effective inhibitory activity than berberine chloride, with good binding energy (DS values: -12.3 to -14.4 kcal/mol) and acceptable RMSD values (0.77-1.75 Å). In general, these identified compounds processed drug properties and were non-toxic for human use, based on Lipinski's rule of five and ADMET analyses.

Reversal of chronic restraint stress-induced memory impairment by Japanese sake yeast supplement in mice: Role of adenosine A1 and A2A receptors

Controversial studies indicate the adenosine compound (a neuromodulator with neuroprotective activity) intervention on cognitive performance. On the other hand, Japanese sake yeast has been enriched with oral adenosine analogs as a novel natural agent. As the first report, we aimed to evaluate the effects of Japanese sake yeast supplement in a mouse model of chronic restraint stress-induced cognitive dysfunction. Mice were subjected to a one-week stress protocol and concomitantly treated orally with sake yeast at the dose level of 100, 200 and 300 mg/kg once daily for a week. The spatial and conditioned fear memory functions were evaluated with the Morris Water Maze (MWM) and the Passive Avoidance Learning (PAL) test, respectively. In all dosing regimens, improvements in spatial cognition were observed significantly in the MWM. 200 and 300 mg/kg of sake yeast significantly improved short- and long-term fear memory functions in the PAL test. Memory-enhancing effect of sake yeast was potentiated by the injection of ZM241385 (15 mg/kg), a selective adenosine A_2A receptor (A_2AR) antagonist, but completely disappeared by the injection of 8-cyclopentyltheophylline (CPT-8, 10 mg/kg), a selective adenosine A₁ receptor (A₁R) antagonist. The findings of the present study demonstrate the efficacy of sake yeast in acting as a cognitive performance-enhancing agent. Eventually, sake yeast and its ingredient S-adenosyl methionine (SAM) may be useful in improving memory in patients suffering from many dementia forms including Alzheimer's disease (AD).

Effects of S-Adenosylmethionine on Cognition in Animals and Humans: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

There is increasing evidence that supplementation of S-adenosylmethionine (SAM) can improve cognitive function in animals and humans, although the outcomes are not always inconsistent.

OBJECTIVE

We conducted a systematic review and meta-analysis to evaluate the correlation between SAM supplementation and improved cognitive function.

METHODS

We searched studies in the PubMed, Cochrane Library, Embase, Web of Science, and Clinical Trials databases from January 1, 2002 to January 1, 2022. Risk of bias was assessed using the Cochrane risk of bias 2.0 (human studies) and the Systematic Review Center for Laboratory Animal Experimentation risk of bias (animal studies) tools; and evidence quality was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation. STATA software was employed to perform meta-analysis, and the random-effects models was used to evaluate the standardized mean difference with 95% confidence intervals.

RESULTS

Out of the 2,375 studies screened, 30 studies met the inclusion criteria. Meta-analyses of animal (p = 0.213) and human (p = 0.047) studies showed that there were no significant differences between the SAM supplementation and control groups. The results of the subgroup analyses showed that the animals aged ≤8 weeks (p = 0.027) and the intervention duration >8 weeks (p = 0.009) were significantly different compared to the controls. Additionally, the Morris water maze test (p = 0.005) used to assess the cognitive level of the animals revealed that SAM could enhance spatial learning and memory in animals.

CONCLUSION

SAM supplementation showed no significant improvement in cognition. Therefore, further studies are needed to assess the effectiveness of SAM supplementation.

Therapeutic roles of plants for 15 hypothesised causal bases of Alzheimer's disease

Alzheimer's disease (AD) is progressive and ultimately fatal, with current drugs failing to reverse and cure it. This study aimed to find plant species which may provide therapeutic bioactivities targeted to causal agents proposed to be driving AD. A novel toolkit methodology was employed, whereby clinical symptoms were translated into categories recognized in ethnomedicine. These categories were applied to find plant species with therapeutic effects, mined from ethnomedical surveys. Survey locations were mapped to assess how this data is at risk. Bioactivities were found of therapeutic relevance to 15 hypothesised causal bases for AD. 107 species with an ethnological report of memory improvement demonstrated therapeutic activity for all these 15 causal bases. The majority of the surveys were found to reside within biodiversity hotspots (centres of high biodiversity under threat), with loss of traditional knowledge the most common threat. Our findings suggest that the documented plants provide a large resource of AD therapeutic potential. In demonstrating bioactivities targeted to these causal bases, such plants may have the capacity to reduce or reverse AD, with promise as drug leads to target multiple AD hallmarks. However, there is a need to preserve ethnomedical knowledge, and the habitats on which this knowledge depends.

Non-Alkaloid Cholinesterase Inhibitory Compounds from Natural Sources

Alzheimer’s disease (AD) is a severe neurodegenerative disorder of different brain regions accompanied by distresses and affecting more than 25 million people in the world. This progressive brain deterioration affects the central nervous system and has negative impacts on a patient’s daily activities such as memory impairment. The most important challenge concerning AD is the development of new drugs for long-term treatment or prevention, with lesser side effects and greater efficiency as cholinesterases inhibitors and the ability to remove amyloid-beta(Aβ) deposits and other related AD neuropathologies. Natural sources provide promising alternatives to synthetic cholinesterase inhibitors and many have been reported for alkaloids while neglecting other classes with potential cholinesterase inhibition. This review summarizes information about the therapeutic potential of small natural molecules from medicinal herbs, belonging to terpenoids, coumarins, and phenolic compounds, and others, which have gained special attention due to their specific modes of action and their advantages of low toxicity and high efficiency in the treatment of AD. Some show superior drug-like features in comparison to synthetic cholinesterase inhibitors. We expect that the listed phytoconstituents in this review will serve as promising tools and chemical scaffolds for the discovery of new potent therapeutic leads for the amelioration and treatment of Alzheimer’s disease.

Natural Products as Potential Anti-Alzheimer Agents

Medicinal plants have curative properties due to the presence of various complex chemical substances of different composition, which are found as secondary metabolites in one or more parts of the plant. The diverse secondary metabolites play an important role in the prevention and cure of various diseases including neurodegenerative diseases like Alzheimer's disease. Naturally occurring compounds such as flavonoids, polyphenols, alkaloids, and glycosides found in various parts of the plant and/or marine sources may potentially protect neurodegeneration as well as improve memory and cognitive function. Many natural compounds show anti-Alzheimer activity through specific pharmacological mechanisms like targeting β-amyloid, Beta-secretase 1 and Acetylcholinesterase. In this review, we have compiled more than 130 natural products with a broad diversity in the class of compounds, which were isolated from different sources showing anti- Alzheimer properties.

Effects of Hippeastrum reticulatum on memory, spatial learning and object recognition in a scopolamine-induced animal model of Alzheimer's disease

CONTEXT

The methanol extracts from Hippeastrum reticulatum (L'Hér.) Herb. (Amaryllidaceae) (HR) display acetylcholinesterase inhibitory (AChEI) activity.

OBJECTIVE

AChEI of alkaloids isolated from HR bulbs and the ameliorating effects of the alkaloid fraction (AHR) on memory and cognitive dysfunction in scopolamine-treated mice were investigated.

MATERIALS AND METHODS

Alkaloids were isolated by column chromatography and identified by spectroscopy. AChEI was evaluated using the modified Ellman's method. Sixty Swiss male mice were randomly divided into six groups, received samples for 15 days. Normal group received saline, scopolamine-treated group scopolamine (1.5 mg/kg, intraperitoneal injection). Test groups received AHR (5, 10 and 15 mg/kg, per os) and positive control group donepezil (5 mg/kg, per os), administered 1 h before the test, scopolamine was injected 30 min prior to testing. The cognitive-enhancing activity of AHR against scopolamine-induced memory impairments was investigated using Y-maze, the novel object recognition test (NORT) and the Morris water maze (MWM) test.

RESULTS

Seven alkaloids were isolated for the first time from the genus Hippeastrum: trans-dihydronarciclasine (1), N-chloromethylnarcissidinium (2), narciprimin (3), narciclasine-4-O-β-d-xylopyranoside (4), N-methyltyramine (5), 3β,11α-dihydroxy-1,2-dehydrocrinane (6) and brunsvigine (7); three are new compounds (2, 5, 6). Among them, 2-3 and 5-6 showed AChEI in vitro with IC₅₀ values of 29.1, 46.4, 70.1 and 104.5 µg/mL, respectively. The anti-AChEI of 2, 5 and 6 are reported for the first time. In in vivo test, AHR (15 mg/kg) significantly increased in spontaneous alternation performance in the Y-maze test (p < 0.01), it significantly increased the time spent exploring the novel object (p < 0.05) comparison with scopolamine-treated group. The administration of AHR at doses 10 and 15 mg/kg significantly decreased escapes latency and swimming distance to the platform on day 6 compared to these in day 1 (p < 0.01 and p < 0.05, respectively).

CONCLUSIONS

AHR could be a potential candidate of future trials for treatment of memory and cognitive dysfunction in Alzheimer's disease.

The complete chloroplast genome sequence of Xylia xylocarpa

The first complete chloroplast genome (cpDNA) sequence of Xylia xylocarpa was determined from Illumina HiSeq pair-end sequencing data in this study. The cpDNA is 161,288 bp in length, contains a large single copy region (LSC) of 89,186 bp and a small single copy region (SSC) of 19,354 bp, which were separated by a pair of inverted repeats (IR) regions of 26,370 bp. The genome contains 131 genes, including 86 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. The overall GC content of the whole genome is 36.6%, and the corresponding values of the LSC, SSC, and IR regions are 34.1%, 30.8%, and 42.8%, respectively. Further phylogenomic analysis showed that X. xylocarpa clustered in a unique clade in Caesalpinioideae subfamily.

Influence of functional moiety in lupane-type triterpenoids in BACE1 inhibition

Lupane-type triterpenoids have shown a potential effect against neurodegenerative disorders. Alzheimer's disease, one of the common neurodegenerative disease, is evident by the accumulation of amyloid-beta (Aβ) plaque in the extracellular regions of the brain. β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is a key enzyme for the Aβ formation viathe cleavage of amyloid precursor protein (APP). Therefore, to find the potent BACE1 inhibitors and furthermore to explore the role of the functional group responsible for the strong BACE1 inhibitory activity, we synthesized a series of triterpenoids with lupane skeleton starting from the natural compounds calenduladiol and lupeol. Compound 1 revealed a potent competitive BACE1 inhibitory activity (IC₅₀ = 16.77 ± 1.16 μM; K_i = 19.38). Furthermore, the molecular docking simulation revealed the importance of Tyr198 residue along with the other hydrophobic interactions for the strong affinity of 1‒BACE1 complex. To sum up, our results demonstrated the importance of carbonyl moiety at 3 and 16 position of lupane-type triterpenoid over the hydroxyl group at the same position.

Recent advances in pharmacological research on Ecklonia species: a review

The genus Ecklonia (Lessoniaceae, Phaeophyceae), commonly called kelp (brown algae), is abundant on the coasts of Japan and Korea. During the past few decades, Ecklonia species have received tremendous attention for their wide range of therapeutic properties and multiple health benefits, such as great nutritional value and being rich in vitamins, minerals, dietary fiber, proteins, and polysaccharides. Several novel functional ingredients with diversified biological activities have been isolated and possess antimicrobial, antiviral, hepatoprotective, cardioprotective, anti-inflammatory, neuroprotective, anticarcinogenic, immunomodulatory, hypolipidemic, anti-diabetic, and antioxidant therapeutic properties. The present review discusses the phytochemical, pharmacological, therapeutic, nutritional, and health benefits of different species of genus Ecklonia, as well as their use in the prevention of disease and maintenance of good health.