Isolation, identification, and quantification of Pentylcurcumene from Geophila repens: A new class of cholinesterase inhibitor for Alzheimer's disease

Revolutionizing neurotherapeutics: Nanocarriers unveiling the potential of phytochemicals in Alzheimer's disease

Neurological disorders pose a huge worldwide challenge to the healthcare system, necessitating innovative strategies for targeted drug delivery to the central nervous system. Alzheimer's disease (AD) is an untreatable neurodegenerative condition characterized by dementia and alterations in a patient's physiological and mental states. Since ancient times, medicinal plants have been an important source of bioactive phytochemicals with immense therapeutic potential. This review investigates new and safer alternatives for prevention and treatment of disease related to inevitable side effects associated with synthetic compounds. This review examines how nanotechnology can help in enhancing the delivery of neuroprotective phytochemicals in AD. Nevertheless, despite their remarkable neuroprotective properties, these natural products often have poor therapeutic efficacy due to low bioavailability, limited solubility and imperfect blood brain barrier (BBB) penetration. Nanotechnology produces personalized drug delivery systems which are necessary for solving such problems. In overcoming these challenges, nanotechnology might be employed as a way forward whereby customized medication delivery systems would be established as a result. The use of nanocarriers in the design and application of important phytochemicals is highlighted by this review, which indicate potential for revolutionizing neuroprotective drug delivery. We also explore the complications and possibilities of using nanocarriers to supply nutraceuticals and improve patients' standard of living, and preclinical as well as clinical investigations displaying that these techniques are effective in mitigating neurodegenerative diseases. In order to fight brain diseases and improve patient's health, scientists and doctors can employ nanotechnology with its possible therapeutic interventions.

The ameliorative effect of Piper trioicum in attenuating cognitive deficit in scopolamine induced neurotoxicity in experimental rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional system of medicine, Piper species, or its components are widely used to treat many diseases including memory improvement. One of the wild species Piper trioicum Roxb. (Piperaceae) is found in South Asian countries. The whole plant is used as folk medicine to improve memory.

AIM OF THE STUDY

To our knowledge, no previous research has investigated the neuroprotective activities of P. trioicum. So, we studied the ameliorative effect of P. trioicum in attenuating cognitive deficit in scopolamine induced neurotoxicity in experimental rats.

MATERIALS AND METHODS

Wistar rats were exposed to scopolamine (3 mg/kg, i. p.) for 14 consecutive days, and the effect of P. trioicum (HAPT; oral, 300, 400 mg/kg) on scopolamine-invoked neurotoxicity in brain were studied. During the experimental period, behaviour analyses of rats were observed 30 min post-drug administration. The role of antioxidants of HAPT in scavenging cellular oxygen/peroxyl radicals were studied. Acetylcholinesterase and butyrylcholinesterase inhibitions, and mode of inhibition kinetics of HAPT were studied. Pathogenic cellular oxidative (MDA, GSH, SOD, and CAT), DNA damage (8-oxodG), neurochemical (acetyl- and, butyryl-cholinesterase), β-secretase (BACE-1 and 2), MAPτ, and neuroinflammation (IL-6, TNF-α) biomarkers in extension to the histopathological observation of brain cortex were studied. GC-MS/MS analysis was carried out to investigate the presence of bioactive constituents in HAPT.

RESULTS

HAPT, a rich source of phenol and flavonoid type antioxidants were responsible in quenching oxygen/peroxyl radicals and protected the cellular membrane, and lipoproteins against ROS in DPPH, ORAC, and CAPe tests. HAPT inhibited acetylcholinesterase and butyrylcholinesterase activities, and showed competitive-inhibition (reversible) towards cholinesterase activities. HAPT-400 significantly improved the learning and memory-impairment by restoring oxidative MDA, GSH, SOD, CAT, and DNA damage (8-oxodG) markers of serum, and cortex. It also improved acetyl- and, butyryl-cholinesterase, β-secretase, and MAPτ level in brain by restoring proinflammatory cytokines IL-6, and TNF-α indicators in neurotoxic rats. GC-MS/MS reported therapeutic significance active compounds were molecular-docked towards target proteins, found that proscillaridin showed the highest affinity towards AChE, BuChE, BACE1, and BACE2 with binding energy of ΔGb -9.1, ΔGb -10.2, ΔGb -11.4 and ΔGb -11.5 Kcal/mol, respectively. Cymarin and morphine-3-glucuronide showed the second highest binding affinity towards AChE (ΔGb -8.8) and BuChE (ΔGb -10.0), respectively. In BACE-1, betulin showed the second highest binding affinity ΔGb -10.7 Kcal/mol and in BACE-2, morphine-3-glucuronide showed the second highest binding affinity ΔGb -9.8 Kcal/mol.

CONCLUSIONS

Synergistic impact of proscillaridin, Cymarin, morphine-3-glucuronide, betulin like compounds in HAPT improved memory impairment, healing of tissue architecture of cortex with the restoration of neurochemical, neuroinflammation, and oxidative indicators in neurotoxic rats.

Citronellal as a Promising Candidate for Alzheimer's Disease Treatment: A Comprehensive Study on In Silico and In Vivo Anti-Acetylcholine Esterase Activity

One of the primary therapeutic approaches for managing Alzheimer's disease (AD) involves the modulation of Acetylcholine esterase (AChE) activity to elevate acetylcholine (ACh) levels inside the brain. The current study employed computational chemistry approaches to evaluate the inhibitory effects of CTN on AChE. The docking results showed that Citronellal (CTN) and standard Donepezil (DON) have a binding affinity of -6.5 and -9.2 Kcal/mol, respectively, towards AChE. Further studies using molecular dynamics (MD) simulations were carried out on these two compounds. Binding free energy calculations and ligand-protein binding patterns suggested that CTN has a binding affinity of -12.2078. In contrast, DON has a much stronger binding relationship of -47.9969, indicating that the standard DON has a much higher binding affinity than CTN for AChE. In an in vivo study, Alzheimer-type dementia was induced in mice by scopolamine (1.5 mg/kg/day i.p) for 14 days. CTN was administered (25 and 50 mg/kg. i.p) along with scopolamine (SCO) administration. DON (0.5 mg/kg orally) was used as a reference drug. CTN administration significantly improved the mice's behavior as evaluated by the Morris water maze test, evident from decreased escape latency to 65.4%, and in the CPS test, apparent from reduced escape latency to 69.8% compared to the positive control mice. Moreover, CTN significantly increased the activities of antioxidant enzymes such as catalase and superoxide dismutase (SOD) compared to SCO. Furthermore, CTN administration significantly decreased SCO-induced elevated AChE levels in mice. These results were supported by histopathological and in silico molecular docking studies. CTN may be a potential antioxidant and neuroprotective supplement.

Phytochemical Compounds and Nanoparticles as Phytochemical Delivery Systems for Alzheimer's Disease Management

Alzheimer's disease remains one of the most widespread neurodegenerative reasons for dementia worldwide and is associated with considerable mortality and morbidity. Therefore, it has been considered a priority for research. Indeed, several risk factors are involved in the complexity of the therapeutic ways of this pathology, including age, traumatic brain injury, genetics, exposure to aluminum, infections, diabetes, vascular diseases, hypertension, dyslipidemia, and obesity. The pathophysiology of Alzheimer's disease is mostly associated with hyperphosphorylated protein in the neuronal cytoplasm and extracellular plaques of the insoluble β-amyloid peptide. Therefore, the management of this pathology needs the screening of drugs targeting different pathological levels, such as acetylcholinesterase (AchE), amyloid β formation, and lipoxygenase inhibitors. Among the pharmacological strategies used for the management of Alzheimer's disease, natural drugs are considered a promising therapeutic strategy. Indeed, bioactive compounds isolated from different natural sources exhibit important anti-Alzheimer effects by their effectiveness in promoting neuroplasticity and protecting against neurodegeneration as well as neuroinflammation and oxidative stress in the brain. These effects involve different sub-cellular, cellular, and/or molecular mechanisms, such as the inhibition of acetylcholinesterase (AchE), the modulation of signaling pathways, and the inhibition of oxidative stress. Moreover, some nanoparticles were recently used as phytochemical delivery systems to improve the effects of phytochemical compounds against Alzheimer's disease. Therefore, the present work aims to provide a comprehensive overview of the key advances concerning nano-drug delivery applications of phytochemicals for Alzheimer's disease management.

Computer Aided Drug Design Methodologies with Natural Products in the Drug Research Against Alzheimer's Disease

Natural products are compounds isolated from plants that provide a variety of lead structures for the development of new drugs by the pharmaceutical industry. The interest in these substances increases because of their beneficial effects on human health. Alzheimer's disease (AD) affects occur in about 80% of individuals aged 65 years. AD, the most common cause of dementia in elderly people, is characterized by progressive neurodegenerative alterations, as decrease of cholinergic impulse, increased toxic effects caused by reactive oxygen species and the inflammatory process that the amyloid plaque participates. In silico studies is relevant in the process of drug discovery; through technological advances in the areas of structural characterization of molecules, computational science and molecular biology have contributed to the planning of new drugs used against neurodegenerative diseases. Considering the social impairment caused by an increased incidence of disease and that there is no chemotherapy treatment effective against AD; several compounds are studied. In the researches for effective neuroprotectants as potential treatments for Alzheimer's disease, natural products have been extensively studied in various AD models. This study aims to carry out a literature review with articles that address the in silico studies of natural products aimed at potential drugs against Alzheimer's disease (AD) in the period from 2015 to 2021.

The modulatory role of prime identified compounds in Geophila repens in mitigating scopolamine-induced neurotoxicity in experimental rats of Alzheimer's disease via attenuation of cholinesterase, β-secretase, MAPt levels and inhibition of oxidative stress imparts inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Geophila repens (L.) I.M. Johnst (Rubiaceae) is a small perennial creeper native to India, China, and other countries in Southeast Asia. The hot decoction of leaves is used orally for memory enhancing by the local folk of Andhra Pradesh, India. The ethnomedicinal claim of G. repens as memory enhancer was initially studied by the authors. Results demonstrated the important antioxidant and anticholinesterase activities of isolated molecule Pentylcurcumene and bioactive hydroalcohol extract of leaves of G. repens (GRHA).

AIM OF THE STUDY

Based on the previous findings, additional research is needed to examine the efficacy of GRHA for memory enhancing properties. We therefore investigated the modulatory role of prime identified compounds in GRHA in mitigating scopolamine-induced neurotoxicity in experimental rats of Alzheimer's disease (AD) via attenuation of cholinesterase, β-secretase, MAPt levels and inhibition of oxidative stress imparts inflammation.

METHODS

Scopolamine (3 mg/kg) induced experimental rats of AD were treated with GRHA (300, 400 mg/kg) for 14 days. During the experimental period, elevated T-maze and locomotion-activity were performed to assess learning and memory efficacy of GRHA. At the end of the experiment, biochemical, neurochemical, neuroinflammation and histopathological observation of brain cortex were examined. GC-MS/MS analysis reported 31 compounds, among them 8 bioactive compounds possess antioxidant, neuroinflammation, neuroprotective activities, and were considered for docking analysis towards cholinesterase, β-secretase activities in AD.

RESULTS

GRHA 400 significantly improved learning and memory impairment with the improvement of oxidative stress (MDA, SOD, GSH, CAT), DNA damage (8-OHdG), neurochemical (AChE, BuChE, BACE1, BACE2, MAPt), neuroinflammation (IL-6, TNF-α) markers in neurotoxic rats. Docking studies of 8 compounds demonstrated negative binding energies for cholinesterase and β-secretase indicating high affinity for target enzymes in AD. Test results were corroborated by the improvement of cellular tissue architecture of brain cortex in AD rats.

CONCLUSION

Synergistic action of genistin, quercetin-3-D-galactoside, 9,12,15-octadecatrienoic-acid methyl-ester, phytol, retinal, stigmasterol, n-hexadecanoic acid, β-sitosterol in GRHA restores memory-deficits via attenuation of cholinesterase, β-secretase, MAPt level and inhibition of oxidative-stress imparts inflammation in AD.

In silico and in vitro anti-AChE activity investigations of constituents from Mytragyna speciosa for Alzheimer's disease treatment

Acetylcholinesterase (AChE), one of the major therapeutic strategies for the treatment of Alzheimer's disease (AD) is to increase the acetylcholine (ACh) level in the brain by inhibiting the biological activity of AChE. In this present work, a set of alkaloids and flavonoids against AChE enzyme were screened by computational chemistry techniques. The docking results showed that among alkaloid compounds the oxindole alkaloid namely mitragynine oxidole B (MITOB) and the indole alkaloids namely mitragynine (MIT) exhibited a good binding affinity towards AChE. These two compounds were then studied by molecular dynamics (MD) simulations. The binding free energy calculation and ligand-protein binding pattern suggested that both alkaloids could interact with AChE very well. Since MIT is the main alkaloid constituent of Mytragyna speciose leaves, this compound was isolated from M. speciose leaves and tested for anti-AChE activity. As a result, the isolated MIT had an inhibitory activity with pIC₅₀ value of 3.57. This finding provided that the mitragynine compound has the potential to be as a therapeutic agent for further anti-AChE drug development in treatment of Alzheimer's disease.

The modulatory role of prime identified compounds in the bioactive fraction of Homalium zeylanicum in high-fat diet fed-streptozotocin-induced type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Homalium zeylanicum (Gardner) Benth. is a medicinal plant traditionally used in controlling diabetes which thus far has been assessed by the authors only to a very limited extent.

PURPOSE

To fill the research gap in the literature review, we investigated the antihyperglycemic effects of hydro alcohol fraction of bark of H. zeylanicum (HAHZB) by modulating oxidative stress and inflammation in high-fat diet fed-streptozotocin (HFD/STZ)-induced type-2 diabetic rats.

MATERIALS AND METHODS

To understand the antioxidant capacity of HAHZB, oxygen radical absorbance capacity (ORAC) and cell-based antioxidant protection in erythrocytes (CAP-e) were performed. GC-MS/MS analysis was performed to assess the bioactive components in HAHZB. HFD/STZ-induced diabetic rats were treated orally with HAHZB (300 and 400 mg/kg) for 28 days. After the end of the experiment, marker profiling and histopathological observation of blood and pancreas were examined. The study also highlights interaction between diabetes, oxidative stress and inflammation by examining the increased pro-inflammatory cytokines e.g. TNF-α and C-reactive protein (CRP) promotes DNA damage e.g. oxidation of 8-hydroxy-2-deoxyguanosine (8-OHdG) in chronic hyperglycaemia.

RESULTS

In ex vivo cellular antioxidant capacity of -CAP-e and ORAC assays, HAHZB showed remarkable free radical scavenging ability in a dose dependent manner. GC-MS/MS analysis identified 28 no. of compounds and out of which, oleic acid (1.03%), ethyl tridecanoate (11.77%), phytol (1.29), 9,12-octadecadienoic acid, methyl ester, (E,E)-(5.97%), stigmasterol (1.30%) and β-sitosterol (2.86%) have antioxidant, anti-inflammatory and anti-diabetic activities. HAHZB 400 mg/kg significantly (p < 0.001) improved the lipid profile (TC: 74.66 ± 0.59, HDL-C: 22.08 ± 0.46, LDL-C: 38.06 ± 0.69, and TG: 171.92 ± 1.01 mg/dL) as well as restoring antidiabetic markers (SG: 209.62 ± 1.05 mg/dL, SI: 15.07 ± 0.11 μIU/mL, HOMA-IR: 7.79 ± 0.04 %, and HbA1C: 8.93 ± 0.03 %) and renal functional markers (Tg: 291.26 ± 0.57 pg/mL, BUN: 23.79 ± 0.14 mg/dL, and Cr: 1.34 ± 0.04 mg/dL) in diabetic rats. Oxidative stress markers of pancreas (MDA: 3.65 ± 0.17 nM TBARS /mg protein, SOD: 3.14 ± 0.28 U/mg protein, CAT: 7.88 ± 0.23 U/mg protein, GSH: 12.63 ± 0.28 µM/g of tissue) were restored to normal as evidenced by histological architecture of pancreatic islet cells. The increased level of pro-inflammatory cytokines and oxidative DNA damage were significantly restored (TNF-α: 54.48 ± 3.19 pg/mL, CRP: 440.22 ± 7.86 ng/mL, and 8-OHdG: 63.65 ± 1.84 ng/mL) by HAHZB in diabetic rats.

CONCLUSION

The present findings confirm that the presence of bioactive compounds in HAHZB exert therapeutic protective effect by decreasing oxidative, inflammation and pancreatic β-cell damage in oxidative stress induced diabetic rats.