Development of a neuroprotective potential algorithm for medicinal plants

Abstract

Medicinal plants are promising candidates for Alzheimer's disease (AD) research but there is lack of systematic algorithms and procedures to guide their selection and evaluation. Herein, we developed a Neuroprotective Potential Algorithm (NPA) by evaluating twenty-three standardized and chemically characterized Ayurvedic medicinal plant extracts in a panel of bioassays targeting oxidative stress, carbonyl stress, protein glycation, amyloid beta (Aβ) fibrillation, acetylcholinesterase (AChE) inhibition, and neuroinflammation. The twenty-three herbal extracts were initially evaluated for: 1) total polyphenol content (Folin-Ciocalteu assay), 2) free radical scavenging capacity (DPPH assay), 3) ferric reducing antioxidant power (FRAP assay), 4) reactive carbonyl species scavenging capacity (methylglyoxal trapping assay), 5) anti-glycative effects (BSA-fructose, and BSA-methylglyoxal assays) and, 6) anti-Aβ fibrillation effects (thioflavin-T assay). Based on assigned index scores from the initial screening, twelve extracts with a cumulative NPA score ≥40 were selected for further evaluation for their: 1) inhibitory effects on AChE activity, 2) in vitro anti-inflammatory effects on murine BV-2 microglial cells (Griess assay measuring levels of lipopolysaccharide-induced nitric oxide species), and 3) in vivo neuroprotective effects on Caenorhabditis elegans post induction of Aβ induced neurotoxicity and paralysis. Among these, four extracts had a cumulative NPA score ≥60 including Phyllanthus emblica (amla; Indian gooseberry), Mucuna pruriens (velvet bean), Punica granatum (pomegranate) and Curcuma longa (turmeric; curcumin). These extracts also showed protective effects on HO induced cytotoxicity in differentiated cholinergic human neuronal SH-SY5Y and murine BV-2 microglial cells and reduced tau protein levels in the SH-SY5Y neuronal cells. While published animal data support the neuroprotective effects of several of these Ayurvedic medicinal plant extracts, some remain unexplored for their anti-AD potential. Therefore, the NPA may be utilized, in part, as a strategy to help guide the selection of promising medicinal plant candidates for future AD-based research using animal models.

Protective Effects of Indian Spice Curcumin Against Amyloid-β in Alzheimer’s Disease

“…Liu and colleagues (2016) [82] developed a neuroprotective potential algorithm (NPA) by evaluating twenty-three standardized and chemically characterized Ayurvedic medicinal plant extracts in a panel of bioassays targeting oxidative stress, carbonyl stress, protein glycation, Aβ fibrillation, acetylcholinesterase (AChE) inhibition, and neuroinflammation. The twenty-three herbal extracts were initially evaluated for: 1) total polyphenol content (Folin-Ciocalteu assay), 2) free radical scavenging capacity (DPPH assay), 3) ferric reducing antioxidant power (FRAP assay), 4) reactive carbonyl species scavenging capacity (methylglyoxal trapping assay), 5) anti-glycative effects (BSA-fructose, and BSA-methylglyoxal assays) and, 6) anti-Aβ fibrillation effects (thioflavin-T assay).…”

Effects of Mucuna pruriens on Free Fatty Acid Levels and Histopathological Changes in the Brains of Rats Fed a High Fructose Diet

“…The brain is highly sensitive to inflammation and inflammatory mediators, and metabolic dysfunction in both humans and laboratory animals has been associated with reactive gliosis and increased brain inflammation [25,26]. Probable effects of M. pruriens that might be responsible for the prevention of membrane degradation, gliosis, hydropic degeneration, and edema in the brain have been reported previously [15,16]. M. pruriens can reduce blood sugar levels by increasing insulin secretion or acting like insulin.…”

“…Antiinflammatory, hypolipidemic, and antithrombotic effects have also been reported [14]. M. pruriens has antioxidant and cytotoxicity-reducing effects, and its effect on neurodegenerative diseases such as Alzheimer and Parkinson diseases has been investigated [15,16].…”

Untitled

“…L-DOPA, the precursor of dopamine, can cross the blood-brain barrier and undergo conversion to dopamine, restoring neurotransmission. [25] Antimicrobial Activity Antimicrobials of plant origin have enormous therapeutic potential. Phytochemical compounds are reportedly responsible for the antimicrobial properties of certain plants.…”

“…M. pruriens plant has many activities which need to elaborate for future cure in Ayurvedic tradition. [15] Antidiabetic Plant seed Ethanol/water (1:1) Cyclitols, oligosaccharides [21] Antioxidant Whole plant Methanol Phenols, tannins [22] Neuroprotective Plant seed, whole plant Ethanol/water (1:1) L-DOPA, amino acids, alkaloids n-propanol Isoquinolines, alkaloids [25] Antimicrobial Plant leave Methanol Tannins, alkaloids, L-DOPA [27] …”