New cholinesterase inhibitors from Garcinia atroviridis

Molecular Multi-Target Approach for Human Acetylcholinesterase, Butyrylcholinesterase and β-Secretase 1: Next Generation for Alzheimer's Disease Treatment

Alzheimer's Disease (AD) is a neurodegenerative condition characterized by progressive memory loss and other affected cognitive functions. Pharmacological therapy of AD relies on inhibitors of the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), offering only a palliative effect and being incapable of stopping or reversing the neurodegenerative process. However, recent studies have shown that inhibiting the enzyme β-secretase 1 (BACE-1) may be able to stop neurodegeneration, making it a promising target. Considering these three enzymatic targets, it becomes feasible to apply computational techniques to guide the identification and planning of molecules capable of binding to all of them. After virtually screening 2119 molecules from a library, 13 hybrids were built and further screened by triple pharmacophoric model, molecular docking, and molecular dynamics (t = 200 ns). The selected hybrid G meets all stereo-electronic requirements to bind to AChE, BChE, and BACE-1 and offers a promising structure for future synthesis, enzymatic testing, and validation.

Two new dilactonized glycerol glycosides of the dual anticholinesterase active extract from Ocotea daphnifolia using bioguided fractionation and molecular docking studies

The dual inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) is considered as an important strategy for the treatment of Alzheimer's disease. In this study, we applied the bioguided fractionations of Ocotea daphinifolia ethyl acetate active extract to furnish a fraction with high inhibitory activity for AChE and BuChE (82% and 92%, respectively). High-performance liquid chromatography semipreparative purification of this fraction provided two new natural products: 1-β-D-galactopyranosyl-glycerol-2,3-heptanedionate, (1) whose complete chemical structural elucidation was made with spectrometric analysis (MS, 1D, and 2D NMR) and its minor derivative 1-β-D-gulopyranosyl-glycerol-2,3-heptanedionate; (2) which could be characterized by 2D ¹ H-¹³ C heteronuclear single-quantum correlation spectra analysis. Investigation of the intermolecular interactions with cholinesterases was carried out by molecular docking studies, and results suggested that both compounds are capable to interact with the catalytic site of both enzymes. Compounds 1 and 2 interact with residues of catalytic domains and the peripheral anionic binding site of AChE and BuChE. The results are comparable to those achieved with rivastigmine and galantamine. Thus, this study provides evidence for consideration of the glycosylglycerol from O. daphnifolia as new valuable dual cholinesterases inhibitor.

Natural Inhibitors of Cholinesterases: Chemistry, Structure-Activity and Methods of Their Analysis

This article aims to provide an updated description and comparison of the data currently available in the literature (from the last 15 years) on the studied natural inhibitors of cholinesterases (IChEs), namely, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). These data also apply to the likely impact of the structures of the compounds on the therapeutic effects of available and potential cholinesterase inhibitors. IChEs are hitherto known compounds with various structures, activities and origins. Additionally, multiple different methods of analysis are used to determine the cholinesterase inhibitor potency. This summary indicates that natural sources are still suitable for the discovery of new compounds with prominent pharmacological activity. It also emphasizes that further studies are needed regarding the mechanisms of action or the structure-activity correlation to discuss the issue of cholinesterase inhibitors and their medical application.

Phytochemicals and Biological Activities of Garcinia atroviridis: A Critical Review

Garcinia atriviridis Griff ex T. Anders (G. atroviridis) is one of the well-known species of the genus Garicinia that is native to Thailand, Myanmar, Peninsular Malaysia, and India. G. atroviridis is a perennial medium-sized tree that has a wide range of values, from food to medicinal use. Different parts of G. atroviridis are a great source of bioactive substances that have a positive impact on health. The extracts or bioactive constituents from G. atroviridis have demonstrated various therapeutic functions, including antioxidant, antimicrobial, anticancer, anti-inflammatory, antihyperlipidemic, and anti-diabetic. In this paper, we provide a critical review of G. atroviridis and its bioactive constituents in the prevention and treatment of different diseases, which will provide new insight to explore its putative domains of research.

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.

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

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

A Bottom-Up Synthesis Approach to Silver Nanoparticles Induces Anti-Proliferative and Apoptotic Activities Against MCF-7, MCF-7/TAMR-1 and MCF-10A Human Breast Cell Lines

A bottom-up approach for synthesizing silver nanoparticles (AgNPs-GA) phytomediated by Garcinia atroviridis leaf extract is described. Under optimized conditions, the AgNPs-GA were synthesized at a concentration of 0.1 M silver salt and 10% (w/v) leaf extract, 1:4 mixing ratio of reactants, pH 3, temperature 32 °C and 72 h reaction time. The AgNPs-GA were characterized by various analytical techniques and their size was determined to be 5–30 nm. FTIR spectroscopy indicates the role of phenolic functional groups in the reduction of silver ions into AgNPs-GA and in supporting their subsequent stability. The UV-Visible spectrum showed an absorption peak at 450 nm which reflects the surface plasmon resonance (SPR) of AgNPs-GA and further supports the stability of these biosynthesized nanoparticles. SEM, TEM and XRD diffractogram analyses indicate that AgNPs-GA were spherical and face-centered-cubic in shape. This study also describes the efficacy of biosynthesized AgNPs-GA as anti-proliferative agent against human breast cancer cell lines, MCF-7 and MCF-7/TAMR-1. Our findings indicate that AgNPs-GA possess significant anti-proliferative effects against both the MCF-7 and MCF-7/TAMR-1 cell lines, with inhibitory concentration at 50% (IC₅₀ values) of 2.0 and 34.0 µg/mL, respectively, after 72 h of treatment. An induction of apoptosis was evidenced by flow cytometry using Annexin V-FITC and propidium iodide staining. Therefore, AgNPs-GA exhibited its anti-proliferative activity via apoptosis on MCF-7 and MCF-7/TAMR-1 breast cancer cells in vitro. Taken together, the leaf extract from Garcinia atroviridis was found to be highly capable of producing AgNPs-GA with favourable physicochemical and biological properties.

Acylphloroglucinol Derivatives from Garcinia multiflora with Anti-Inflammatory Effect in LPS-Induced RAW264.7 Macrophages

Two new acylphloroglucinol derivatives, 13,14-didehydroxygarcicowin C (1) and 13,14-didehydroxyisoxanthochymol (2), have been isolated from the stems of Garcinia multiflora, together with seven known compounds (3⁻9). The structures of new compounds 1 and 2 were elucidated by MS and extensive 1D/2D NMR spectroscopic analyses. Among the isolates, 13,14-didehydroxy-isoxanthochymol (2) and sampsonione B (3) exhibited inhibition against lipopolysaccharide (LPS)-induced NF-κB activation in macrophages at 30 μM with relative luciferase activity values (inhibitory %) of 0.75 ± 0.03 (24 ± 4%) and 0.12 ± 0.03 (88 ± 4%), respectively. Additionally, sampsonione B (3) reduced LPS-induced nitric oxide (NO) production in murine RAW264.7 macrophages and did not induce cytotoxicity against RAW 264.7 cells after 24 h treatment. Compound 3 is worth further investigation and may be expectantly developed as an anti-inflammatory drug candidate.

Antioxidant compounds from the stem bark of Garcinia atroviridis

A new xanthone, namely garcinexanthone G (1), along with eight known compounds, stigmasta-5,22-dien-3β-ol (2), stigmasta-5,22-dien-3-O-β-glucopyranoside (3), 3β-acetoxy-11α,12α-epoxyoleanan-28,13β-olide (4), 2,6-dimethoxy-p-benzoquinone (5), 1,3,5-trihydroxy-2-methoxyxanthone (6), 1,3,7-trihydroxyxanthone (7), kaempferol (8) and quercetin (9), were isolated from the stem bark of Garcinia atroviridis. Their structures were elucidated based on spectroscopic methods including nuclear magnetic resonance (NMR-1D and 2D), UV, IR, and mass spectrometry. All the isolated compounds were evaluated for their antioxidant properties based on the DPPH radical scavenging activities. Results showed that 1,3,7-trihydroxyxanthone and quercetin showed significant antioxidant activities with EC50 values of 16.20 and 12.68 μg/ml, respectively, as compared to the control, ascorbic acid (7.4 μg/ml).