Modulatory Effects of Alkaloid Extract from Gongronema latifolium (Utazi) and Lasianthera africana (Editan) on Activities of Enzymes Relevant to Neurodegeneration

Effect of Flavonoid-Rich Extract From Dalbergiella welwitschii Leaf on Redox, Cholinergic, Monoaminergic, and Purinergic Dysfunction in Oxidative Testicular Injury: Ex Vivo and In Silico Studies

The antioxidant, cholinergic, monoaminergic, and purinergic activities of flavonoid-rich extract from Dalbergiella welwitschii leaf (FEDW) were investigated on oxidative testicular injury (ex vivo) due to the local report on the use of this plant as anti-testicular injury. Flavonoid extract was obtained from FEDW using a standard procedure. Five male albino rats were used, testes harvested and incubated with FeSO₄ for accessing the cholinergic, monoaminergic, and purinergic activities of the FEDW (ex vivo). Testicular tissues incubated with FeSO₄ demonstrated a significant decrease in antioxidant biomarkers, arginase, ATPase, ENTPDase, 5'-nucleotidase, and PDE-5 activities, as well as Zn and sialic acid levels with an upsurge in malondialdehyde (MDA), and NO levels, myeloperoxidase, cholinesterases, monoamine oxidase (MAO), and angiotensin-converting enzyme (ACE) activities. Treatment of testicular tissues incubated with FeSO₄ via different concentrations of FEDW significantly increased the activities of antioxidant, arginase, ATPase, E-NTPDase, 5'-nucleotidase, phosphodiesterase-5 (PDE-5), as well as Zn and sialic acid levels with a significant decrease in MDA, nitric oxide (NO), myeloperoxidase, cholinesterases, MAO, and ACE levels. Molecular docking revealed the molecular interactions of cyclooxygenase-2 (COX-2) with ellagic acid, piperine, and caffeine with piperine and caffeine obeyed the druggability and pharmacokinetic. These findings point to FEDW as a possible potential for the treatment of oxidative testicular injury.

Lycopene suppresses palmitic acid-induced brain oxidative stress, hyperactivity of some neuro-signalling enzymes, and inflammation in female Wistar rat

Neuroinflammation can be triggered by certain high caloric nutrients such as palmitic acid (PA). The effect of lycopene against PA-induced neuroinflammation in female rats has not been as explored. In the present study, thirty rats (weighing 150–200) g were randomly allotted into six groups (n = 5) comprising normal control, PA control, PA + lycopene (0.24 mg/kg), PA + lycopene (0.48 mg/kg), lycopene (0.24 mg/kg), and lycopene (0.48 mg/kg), respectively. After seven weeks of PA challenge (5 mM) including two weeks of lycopene treatment, the brain was excised for analyses. Palmitic acid overload caused significant (p < 0.05) increases in adenosine deaminase, monoamine oxidase-A, nucleotides tri-phosphatase, 5′-nucleotidase, acetylcholine esterase, and myeloperoxidase activities, and malondialdehyde (MDA) levels which were reduced significantly in the lycopene-treated groups. Conversely, catalase and glutathione peroxidase activities, and reduced glutathione levels concentration decreased by 43%, 34%, and 12%, respectively in the PA control groups compared with the Control. Also, PA triggered a decrease in the brain phospholipids (11.43%) and cholesterol (11.11%), but increased triacylglycerol level (50%). Furthermore, upregulated expressions of Interleukin-1β, Interleukin-6, and NF-ĸB-p65 in the PA control were attenuated, while decreased Interleukine-10 expression was upregulated due to lycopene treatment. Severe brain vacuolation observed in the histology of the PA control rats was normalized by lycopene. This study concludes that lycopene ameliorated PA-induced neuroinflammation, probably via attenuation of oxidative stress, and downregulation of TLR4/ NF-κB -p65 axis.

Solanum leaves extracts exhibit antioxidant properties and inhibit monoamine oxidase and acetylcholinesterase activities (in vitro) in Drosophila melanogaster

Background This study sought to determine the in vitro antioxidant, anti-monoamine oxidase and anticholinesterase properties of extracts (aqueous and alkaloid) of two tropical vegetables from Solanum spp- African eggplant (Solanum macrocarpon L) and black nightshade (Solanum nigrum L) as indices of their neuroprotective properties. Methods Both aqueous and alkaloid extracts of African eggplant (AE) and black nightshade (BN) were prepared by solvent extraction according to standard methods. Thereafter, the inhibitory effects of the extracts on monoamine oxidase (MAO) and acetylcholinesterase (AChE) activities, as well as their free radical-scavenging and reducing abilities were assessed. Also, phytochemical analysis for phenols, flavonoids, and alkaloids were carried out. Results The results showed that the extracts inhibited MAO and AChE activities dose dependently, with aqueous extracts showing significantly higher MAO inhibition that the alkaloid extracts from both samples, but in all, BN showed higher MAO inhibitory effect compared to AE; the reverse was however, observed for AChE inhibition. Furthermore, the aqueous extracts showed significantly higher antioxidant properties than the alkaloid extracts, while BN had higher antioxidant properties compared to AN. The phytochemical analysis also showed that BN had significantly higher amount of phenols, flavonoids, and alkaloids than AE. Conclusions The anti-monoamine oxidase, anticholinesterase, and antioxidant properties exhibited by extracts from both samples could contribute to their neuroprotective abilities. Thus, these vegetables can be potential sources of functional foods and nutraceuticals in the management of neurodegenerative diseases, especially in the tropics.

Rutin alleviates cadmium-induced neurotoxicity in Wistar rats: involvement of modulation of nucleotide-degrading enzymes and monoamine oxidase

Rutin is a flavonoid commonly found in many vegetables, fruits and other plant species. Thus, this study investigated the protective role of rutin on cognitive function and impairment of ectonucleotidase, monoamine oxidase (MAO) and antioxidant enzymes activities in the cortex and hippocampus of cadmium-induced rats. Cognitive impairment was induced by an oral administration of 5 mg/kg Cadmium chloride for 14 consecutive days. Rutin was dissolved in 2% dimethyl sulfoxide (DMSO) and administered orally at the doses of 25 and 50 mg/kg for 14 days. Thereafter, animals were divided into six groups (n = 6) as follows: control, rutin 25 mg/kg, rutin 50 mg/kg, cadmium, cadmium plus rutin 25 mg/kg, cadmium plus rutin 50 mg/kg. After treatment period of 14 days, animals were sacrificed and the brain was dissected into cortex and hippocampus. Results showed that cadmium caused a significant increase in ectonucleotidases, adenosine deaminase (ADA) and MAO activities, with a concomitant decrease in thiol levels and antioxidant enzymes activities. However, treatment with rutin decreased ectonucleotidase, ADA and MAO activities in cadmium-induced rats. In addition, rutin reduced residual level of cadmium ion in the brain of cadmium-induced rats. Conclusively, present findings revealed that rutin could prevent/restored the impairment of the enzymes that regulate the purinergic and monoaminergic extracellular signaling and restore antioxidant status in cognitive impairment caused by prolonged cadmium exposure.

Effect of Alkaloid Extract from African Jointfir (Gnetum africanum) Leaves on Manganese-Induced Toxicity in Drosophila melanogaster

Metal-induced toxicity in fruit fly (Drosophila melanogaster) is one of the established models for studying neurotoxicity and neurodegenerative diseases. Phytochemicals, especially alkaloids, have been reported to exhibit neuroprotection. Here, we assessed the protective effect of alkaloid extract from African Jointfir (Gnetum africanum) leaf on manganese- (Mn-) induced toxicity in wild type fruit fly. Flies were exposed to 10 mM Mn, the alkaloid extract and cotreatment of Mn plus extract, respectively. The survival rate and locomotor performance of the flies were assessed 5 days posttreatment, at which point the flies were homogenized and assayed for acetylcholinesterase (AChE) activity, nitric oxide (NO), and reactive oxygen species (ROS) levels. Results showed that the extract significantly reverted Mn-induced reduction in the survival rate and locomotor performance of the flies. Furthermore, the extract counteracted the Mn-induced elevation in AChE activity, NO, and ROS levels. The alkaloid extract of the African Jointfir leaf may hence be a source of useful phytochemicals for the development of novel therapies for the management of neurodegeneration.

Modulatory effect of some citrus (Citrus limon, Citrus reticulata, Citrus maxima) peels on monoamine oxidase, phosphodiesterase-5 and angiotensin-1 converting enzyme activities in rat heart homogenate

Background

Citrus peels have been reported useful in folk medicine for the management of cardiovascular diseases, but there is dearth of information on the possible mechanisms for their therapeutic action. The aim of this study was to investigate the effect of methanolic extracts from some citrus [lime (Citrus limon), tangerine (Citrus reticulata), shaddock (Citrus maxima)] peels on some enzymes relevant to the management of cardiovascular diseases [monoamine oxidase (MAO), phosphodiesterase-5 (PDE-5) and angiotensin-1-converting enzyme (ACE)].

Methods

Effect of methanolic extracts of lime, tangerine and shaddock peels on MAO, PDE-5 and ACE were carried out using standard methods. In addition, the ability of the extracts to prevent oxidative damage in rat heart homogenates was also investigated. Finally, the total polyphenol content of extracts was determined.

Results

The results revealed that methanolic extracts of lime, tangerine and shaddock peels inhibited MAO, PDE-5, ACE and pro-oxidants induced lipid peroxidation in rat heart homogenate in a concentration-dependent manner.

Conclusions

Findings in this study revealed citrus peel methanolic extracts as natural inhibitor of enzymes (MAO, PDE-5 and ACE) implicated in cardiovascular diseases. Therefore, citrus peels could help in the management of cardiovascular diseases possibly through inhibition of these enzymes.

In vitro anticholinesterase, antimonoamine oxidase and antioxidant properties of alkaloid extracts from kola nuts (Cola acuminata and Cola nitida)

Background

The development of cholinesterase (ChE) and monoamine oxidase (MAO) inhibitors for management of neurodegenerative diseases such as Alzheimer’s disease (AD) has come with their undesirable side effects. Hence, research for potent but natural ChE and MAO inhibitors with little or no side effects is essential. This study investigated the potentials of alkaloid extracts from two Cola species as nutraceuticals for prevention and management of AD.

Methods

Alkaloid extracts were obtained from two Cola species (Cola nitida [KN] and Cola acuminata [KA]) by solvent extraction method. The extracts were characterized for their alkaloid contents using gas chromatography (GC). The effects of the extracts on ChE and MAO activities were investigated in vitro. Also, the extracts’ ability to inhibit Fe2+-induced lipid peroxidation in rat brain homogenate, scavenge DPPH and OH radicals, as well as chelate Fe2+ were determined.

Results

GC characterization revealed the presence of augustamine and undulatine as the predominant alkaloids in the extracts. There was no significant (P > 0.05) difference in the inhibitory effects of the extracts on ChE activities. However, KA extract exhibited significantly higher (P < 0.05) MAO inhibitory effect than KN. Also, KA extract inhibited Fe2+- induced malondialdehyde (MDA) production in rat brain homogenate more significantly than KN, while there was no significant difference in DPPH and OH radicals scavenging, as well as Fe2+-chelating abilities of the extracts.

Conclusions

Our findings revealed that KN and KA alkaloid extracts exhibited significant effect in vitro on biological pathways that may contribute to neuroprotection for the management of neurodegenerative diseases.