Anti‐cholinesterase and antioxidant properties of alkaloid and phenolic‐rich extracts from pawpaw (Carica papaya) leaf: A comparative study

Abstract

Carica papaya, commonly known as pawpaw, is a tropical plant cultivated for its edible ripe fruits. However, its leaf is being use traditionally against several life‐threatening illnesses, including Alzheimer disease (AD). This study compared the cholinesterases (ChEs) inhibitory effect and antioxidant property of alkaloid and phenolic [aqueous, acetone and methanol‐HCL (0.1:50 w/v)] rich extracts of Pawpaw leaf. The extracts were prepared to the concentration of 2 mg/mL, thereafter, effect on ChEs [acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)] activities, and production of quinolone (QA) and Fe‐induced thiobarbituric reactive acid species (TBARS)] as well as antioxidant [ferric reducing antioxidant property (FRAP), 2, 2‐diphenyl‐1‐ picrylhydrazyl (DPPH) radical scavenging ability] properties were determined. Total phenol and flavonoid contents of the phenolic‐rich extracts, as well as gas chromatography analysis of an alkaloid extract, were carried out. Results revealed that hydromethanolic extract had the highest AChE inhibitory effect while aqueous extract had the highest BChE inhibitory potential. Hydromethanolic extract demonstrated highest inhibitory effect on Fe2+‐induced TBARS production, while alkaloid extract had strong inhibition on QA‐induced TBARS production. Aqueous extract had the highest total phenol content, while hydromethanolic extract had the highest total flavonoid content. All the extract exhibited anticholinesterases and antioxidant properties, however, hydromethanolic extract appears to be the most potent and could be as a result of its rich flavonoid content. The biological properties of the studied extract could be the underlying neuromodulatory mechanism of actions of pawpaw leaf in folklore against some neurological disorders.

Phytochemical Analysis, In Vitro Anticholinesterase, Antioxidant Activity and In Vivo Nootropic Effect of Ferula ammoniacum (Dorema ammoniacum) D. Don. in Scopolamine-Induced Memory Impairment in Mice

“…Fa.EtAc fraction was found rich in phenolics and flavonoids that might thus be capable of reducing the risk of various degenerative diseases including AD, by prompting antioxidative activities. Previous studies also revealed that phenolics and flavonoids act as free radical scavengers of many oxidizing species and are inhibitors of cholinesterases (AChE and BChE) [ 49 ]. Further studies are needed to isolate and characterize the bioactive phytochemical compounds to be used as a promising candidate drug in management of AD.…”

Citrus spp . essential oils improve behavioral pattern, repressed cholinesterases and monoamine oxidase activities, and production of reactive species in fruit fly ( Drosophila melanogaster ) model of Alzheimer’s Disease

“…Thus, suggesting therapeutic potentials of the EOs. Oxidative stress has been connected to the progression of AD (Adedayo et al., 2020; Ademosun & Oboh, 2014), via induction of selective loss of neurons and deposition of β‐amyloid protein in AD brain (Butterfield et al., 2002). Nerve impulses are needed to coordinate the necessary organs involved in movement during locomotion, hence, the reduced locomotive performance experienced in the transgenic control flies might have resulted from the excessive accumulation of the β‐amyloid protein, which might have induced the disruption of neurotransmission signaling necessary to coordinate movement of the flies.…”

“…Unchecked increased production of free radicals overwhelm the antioxidant defense mechanisms of the body, and in turn leads to oxidative stress and progression of AD (Akinyemi et al., 2014; Axelsen et al., 2011; Jenner, 1998). However, improving the body's antioxidant via consumption of antioxidant‐rich diets could be an effective approach toward the management of neurodegeneration (Adedayo et al., 2020; Olasehinde et al., 2020). This study further shows that there was an increase in ROS and TBARS levels compared to the control flies.…”

“…However, inhibitors of MAO and ChEs activities have also been found to improve cognition in the deteriorating brain (Ademosun & Oboh, 2014; Lane et al., 2006). The use of antioxidant may thus slow the disease progression (Rottkamp et al., 2000) by scavenging radical species (Adedayo et al., 2020; Ademosun & Oboh, 2014).…”

Application of HPLC-DAD for In Vitro Investigation of Acetylcholinesterase Inhibition Activity of Selected Isoquinoline Alkaloids from Sanguinaria canadensis Extracts

“…Acetylcholinesterase in vitro inhibition was investigated by spectrophotometry [6,7,9,12,14,[16][17][18]20,22,[26][27][28][29][30]. Usually acetylcholinesterase activity was determined according to Ellman et al [31].…”