Compounds from the aerial parts of Piper bavinum and their anti-cholinesterase activity

A highly selective C-rhamnosyltransferase from Viola tricolor and insights into its mechanisms

C-Glycosides are important natural products with various bioactivities. In plant biosynthetic pathways, the C-glycosylation step is usually catalyzed by C-glycosyltransferases (CGTs), and most of them prefer to accept uridine 5'-diphosphate glucose (UDP-Glc) as sugar donor. No CGTs favoring UDP-rhamnose (UDP-Rha) as sugar donor has been reported, thus far. Herein, we report the first selective C-rhamnosyltransferase VtCGTc from the medicinal plant Viola tricolor. VtCGTc could efficiently catalyze C-rhamnosylation of 2-hydroxynaringenin 3-C-glucoside, and exhibited high selectivity towards UDP-Rha. Mechanisms for the sugar donor selectivity of VtCGTc were investigated by molecular dynamics (MD) simulations and molecular mechanics with generalized Born and surface area solvation (MM/GBSA) binding free energy calculations. Val144 played a vital role in recognizing UDP-Rha, and the V144T mutant could efficiently utilize UDP-Glc. This work provides a new and efficient approach to prepare flavonoid C-rhamnosides such as violanthin and iso-violanthin.

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.

Insights into the Phytochemical and Multifunctional Biological Profile of Spices from the Genus Piper

Piper spices represent an inexhaustible reservoir of bioactive compounds that may act as drug leads in natural product research. The aim of this study was to investigate a series of methanolic fruit extracts obtained from P. nigrum (black, green, white and red), P. longum and P. retrofractum in comparative phytochemical and multi-directional biological (antimicrobial, antioxidant, anti-enzymatic and anti-melanogenic) assays. The metabolite profiling revealed the presence of 17 piperamides, with a total content of 247.75-591.42 mg piperine equivalents/g. Among the 22 tested microorganism strains, Piper spices were significantly active (MIC < 0.1 mg/mL) against the anaerobes Actinomyces israelii and Fusobacterium nucleatum. The antioxidant and anti-enzymatic activities were evidenced in DPPH (10.64-82.44 mg TE/g) and ABTS (14.20-77.60 mg TE/g) radical scavenging, CUPRAC (39.94-140.52 mg TE/g), FRAP (16.05-77.00 mg TE/g), chelating (0-34.80 mg EDTAE/g), anti-acetylcholinesterase (0-2.27 mg GALAE/g), anti-butyrylcholinesterase (0.60-3.11 mg GALAE/g), anti-amylase (0.62-1.11 mmol ACAE/g) and anti-glucosidase (0-1.22 mmol ACAE/g) assays. Several Piper extracts (10 μg/mL) inhibited both melanin synthesis (to 32.05-60.65% of αMSH+ cells) and release (38.06-45.78% of αMSH+ cells) in αMSH-stimulated B16F10 cells, partly explained by their tyrosinase inhibitory properties. Our study uncovers differences between Piper spices and sheds light on their potential use as nutraceuticals or cosmeceuticals for the management of different diseases linked to bacterial infections, Alzheimer's dementia, type 2 diabetes mellitus or hyperpigmentation.

Propolis and Its Gastroprotective Effects on NSAID-Induced Gastric Ulcer Disease: A Systematic Review

Gastric ulcer disease induced by the consumption of NSAIDs is a major public health problem. The therapy used for its treatment causes adverse effects in the patient. Propolis is a natural product that has been used for the treatments of different diseases around the world. Nevertheless, there is little information about the activity of propolis in gastric ulcers caused by treatment with NSAIDs. Therefore, this review evaluates and compares the gastroprotective potential of propolis and its function against NSAID-induced gastric ulcers, for which a systematic search was carried out in the PubMed and ScienceDirect databases. The main criteria were articles that report the gastroprotective activity of propolis against the damage produced by NSAIDs in the gastric mucosa. Gastroprotection was related to the antioxidant, antisecretory, and cytoprotective effects, as well as the phenolic compounds present in the chemical composition of propolis. However, most of the studies used different doses of NSAIDs and propolis and evaluated different parameters. Propolis has proven to be a good alternative for the treatment of gastric ulcer disease. However, future studies should be carried out to identify the compounds responsible for these effects and to determine their potential use in people.

Ampelopsin Improves Cognitive Impairment in Alzheimer's Disease and Effects of Inflammatory Cytokines and Oxidative Stress in the Hippocampus

BACKGROUND

Neuroinflammation and oxidative stress have significant effects on cognitive deficiency in the pathophysiological development of Alzheimer's disease (AD). In the present study, we studied the influences of Ampelopsin (AMP) on proinflammatory cytokines (PICs, IL-1β, IL-6 and TNF-α), and products of oxidative stress 8-isoprostaglandin F2α (8-iso PGF2α, a product of oxidative stress); and 8-hydroxy-2'-deoxyguanosine (8-OHdG, a key biomarker of protein oxidation) in the hippocampus using a rat model of AD.

METHODS

ELISA was used to examine PICs and oxidative stress production; and western blotting to examine NADPH oxidase (NOXs). The Spatial working memory tests and Morris water maze were utilized to assess cognitive functions.

RESULTS

We observed amplification of IL-1β, IL-6 and TNF-α as well as 8-iso PGF2α and 8-OHdG in the hippocampus of AD rats. AMP attenuated upregulation of PICs and oxidative stress production. AMP also inhibited NOX4 in the AD rat hippocampus. Notably, AMP mostly improved learning performance in AD rat and this was linked to signal pathways of PIC and oxidative stress.

CONCLUSION

AMP plays a significant role in improving the memory deficiency in AD rats via inhibition of signal pathways of neuroinflammation and oxidative stress, suggesting that AMP is likely to prospect in preventing and relieving development of the cognitive dysfunctions in AD as a complementary alternative intervention.

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.

Secondary metabolites in a neotropical shrub: spatiotemporal allocation and role in fruit defense and dispersal

Deciphering the ecological roles of plant secondary metabolites requires integrative studies that assess both the allocation patterns of compounds and their bioactivity in ecological interactions. Secondary metabolites have been primarily studied in leaves, but many are unique to fruits and can have numerous potential roles in interactions with both mutualists (seed dispersers) and antagonists (pathogens and predators). We described 10 alkenylphenol compounds from the plant species Piper sancti-felicis (Piperaceae), quantified their patterns of intraplant allocation across tissues and fruit development, and examined their ecological role in fruit interactions. We found that unripe and ripe fruit pulp had the highest concentrations and diversity of alkenylphenols, followed by flowers; leaves and seeds had only a few compounds at detectable concentrations. We observed a nonlinear pattern of alkenylphenol allocation across fruit development, increasing as flowers developed into unripe pulp then decreasing as pulp ripened. This pattern is consistent with the hypothesis that alkenylphenols function to defend fruits from pre-dispersal antagonists and are allocated based on the contribution of the tissue to the plant's fitness, but could also be explained by non-adaptive constraints. To assess the impacts of alkenylphenols in interactions with antagonists and mutualists, we performed fungal bioassays, field observations, and vertebrate feeding experiments. In fungal bioassays, we found that alkenylphenols had a negative effect on the growth of most fungal taxa. In field observations, nocturnal dispersers (bats) removed the majority of infructescences, and diurnal dispersers (birds) removed a larger proportion of unripe infructescences. In feeding experiments, bats exhibited an aversion to alkenylphenols, but birds did not. This observed behavior in bats, combined with our results showing a decrease in alkenylphenols during ripening, suggests that alkenylphenols in fruits represent a trade-off (defending against pathogens but reducing disperser preference). These results provide insight into the ecological significance of a little studied class of secondary metabolites in seed dispersal and fruit defense. More generally, documenting intraplant spatiotemporal allocation patterns in angiosperms and examining mechanisms behind these patterns with ecological experiments is likely to further our understanding of the evolutionary ecology of plant chemical traits.

Anti-Inflammatory Compounds from Vietnamese Piper bavinum

This study reports the anti-inflammatory activity-guided fractionation of the aerial part of Piper bavinum C. CD. (Piperaceae) that led to the isolation of eight secondary metabolites (1–8). The chemical structures of 1–8 were established mainly by NMR and mass spectra. Compound 5 was isolated from P. bavinum for the first time. All the isolated compounds were evaluated against LPS-induced NO production in macrophage RAW 264.7 cells in vitro. Among them, compound 4 showed the most potent inhibitory activity against the LPS-induced NO production with an IC50 value of 5.2 μM followed by compound 5 that inhibited NO production with an IC50 value of 13.5 μM. In the protein levels, compound 4 suppressed LPS-induced COX-2 and iNOS expressions in a dose-dependent manner. The results suggested that P. bavinum and its constituents might exert anti-inflammatory effects.

Pharmacophore-based drug design for the identification of novel butyrylcholinesterase inhibitors against Alzheimer's disease

BACKGROUND

Alzheimer's disease is a severe neurodegenerative disease of the central nervous system in the elderly.

HYPOTHESIS/PURPOSE

In our study, we aimed to find the best potential small molecule for AD treatment.

STUDY DESIGN

We used many models in Discovery Studio 2016 to find new potential inhibitors of butyrylcholinesterase (BChE), including pharmacophore model, virtual screening model, molecular docking model, de novo evolution model.

METHODS

Ligand-based pharmacophore models were used to identify the critical chemical features of BChE inhibitors using the module of 3D QSAR Pharmacophore Generation in Discovery Studio 2016. The best pharmacophore model was then validated by cost analysis, Fischer's randomization method, 3D-QSAR Method of the training set and test set. The compounds that match the best pharmacophore model with the predicted activity <1 μM filtered by Lipinski's rule of five were subjected to molecular docking.

RESULT

After virtual screening, 35 compounds filtered by Lipinski's rule of five and ADMET analysis were subjected to molecular docking and then the number were narrowed down on 10 compounds based on -CDOCKER_ENERGY. Finally, we obtained and modified the best potential candidate ENA739155.

CONCLUSION

Ultimately, ENA739155_Evo with -CDOCKER_ENERGY of 47.12, estimate activity of 0.012, fit value of 10.02 could be further subjected to drug development and forwarded as better alternatives to the current batch of medicines used for the treatment of AD.

Oral administration of ampelopsin protects against acute brain injury in rats following focal cerebral ischemia

Ampelopsin (AMP) is isolated from the Chinese medicinal herb Ampelopsis grossedentata (Hand-Mazz) and has been associated with numerous biological and pharmacological activities. However, it is not clear whether AMP has a direct protective effect on cerebral ischemia reperfusion injury. Therefore, the present study investigated its role in acute brain injury following focal cerebral ischemia in rats. The current study induced transient focal cerebral ischemia by performing middle cerebral artery occlusion (MCAO) for 60 min, followed by 24 h of reperfusion. Rats were exposed to 40, 80 and 160 mg/kg AMP by oral administration 30 min prior to MCAO and the cysteinyl leukotriene receptor 1-antagonist, pranlukast (0.1 mg/kg, i.p.) was used as a positive control. Neurological deficit scores were observed and an inclined board test was used to assess behavioral dysfunction. The coronal slices were stained with 3,5-triphenyltetrazolium chloride to determine the infarct volume and brain edema. Neuronal morphology was assessed in brain sections stained with cresyl violet and degenerating neurons were identified using Fluoro-Jade B staining. Blood-brain barrier permeability was determined with immunoglobulin (Ig)G immunohistochemistry. Interleukin (IL)-1β, tumor necrosis factor-α (TNF-α) in serum and cerebrospinal fluid were measured using ELISA kits. AMP at 80 and 160 mg/kg attenuated neurological deficits, reduced infarct volume, brain edema, IgG exudation and neuron degeneration and loss. Similar to pranlukast, AMP also inhibited the MCAO-induced IL-1β and TNF-α release. Thus, AMP has a neuroprotective effect on acute brain injury following focal cerebral ischemia in rats at an effective oral dose of 80-160 mg/kg. The results of the current study indicate a therapeutic role for AMP in the treatment of ischemic stroke.