In‐vitro Anticholinesterases Screening and antioxidant activity of three standardized herbal products used in ethnomedicine of South‐East Nigeria
Authors: Nwidu Lucky Legbosi , Elmorsy Ekramy , Carter Wayne Grant 
Published: November 2023

Many herbal drugs possess multiple pharmacological actions which in part hinges on its anti‐oxidant properties, which could act through multiple pathways and may offer beneficial effects in the management of multi‐factorial diseases like Alzheimer, Parkinson's and other neurodegenerative conditions. In the present investigation, in vitro anticholinesterases, DPPH antioxidant, ferric reducing power capacity and total phenolic contents of crude methanolic extracts of three standardized herbal products (Neocare herbal tea (NHT), Herbalin complex tea (HCT) and Phytoblis herbal tea (PHT) used in ethnomedicine of Eastern Nigeria were studied to established ethnomedicinal claim.

The extracts were scrutinized for anticholinesterases activity using Ellman's Assay. DPPH free radical scavenging activities and ferric reducing capacity were investigated by spectrophotometric assays. Total phenolics and flavonoid contents were estimated and expressed in mg GAE/g and mg Quercetin E/g of samples respectively.

All herbal extracts exhibited significant concentration dependent AChE inhibitory activity (p < 0.01–0.001). The extract with the highest AChE inhibition is NHT with 99.7 % (IC50= 324 μg/ml); HCT and PHT demonstrate 73.77 (IC50= 0.2 μg/ml) and 60.6 % (IC50 = 0.7 μg/ml) respectively compared to eserine with AChE inhibition of 148.26% (IC50= 0.9 μg/ml) at 200μg/ml. The order of strength of inhibition of AChE is: NHT > HCT > PHT and the order of potency is HCT > PHT > NHT when compared to eserine.

In DPPH free radicals scavenging assay, HCT, NHT and PHT showed high percentage of radical scavenging activities; 82.13, 77.43 and 76.28 % inhibition of free radicals respectively at 1 mg/mL concentration was observed. The IC50 of antioxidant activity of these three herbal products, HCT, NHT and PHT, are 0.08, 0.01 and 0.3 μg/ml respectively. The reducing power assessed by ferric to ferrous reduction activity by the extracts revealed a dose dependent effect with NHT > PHT > HCT. Thus NHT demonstrate most active antioxidant activity from DPPH and reducing capacity assessment while NHT demonstrate highest AChE activity with low potency.

The order of total phenolics content (TPC) in the extract showed that PHT > HCT > NHT and for total flavonoids content (TFC) PHT > NHT > HCT dose dependently (p < 0.0001).

The study established that these three standardized herbal products possesses potential phenolic contents with significant anticholinesterases and antioxidant activities. This investigation provides preliminary evidence that the herbal extracts could be useful as a neuroprotective and for treatment of Alzheimer disorders.

Support or Funding Information

University of Nottingham Visiting Fellowship

Name of Standardized Herbal products, components and yield of methanolic extract

S/No.
Names of Herbal product
Constituents/Common name
Family
Composition (%)
Yield (%)

1
Neocare herbal tea

4.22

NHT
(9a)

Alcornea cordifolia (Christmas bush)
Euphurbiaceae
25

Azadirachta indica (Neem leaves)
Meliaceae
25

Pteridium acquilinum (Fern)
Dennstaedtiaceae.
50

2
Herbalin complex

5.52%

HCT
10a

Hippocratea volubilis (Hepocreatea pollens)
Hippocreateaceae
50

Viscum album
Santalaceae
25

Thymus pulegiodes (Mother thyme)
Meliaceae
25

3.
Phytoblis herbal tea

5.24%

PHT
1 la

Urtica dioica (Stinging nettles)
Urticaceae
25

Hippocratea volubilis (Hepocreatea pollens)
Hippocreateaceae
50

Thymus vulgaris (thyme)
Meliaceae
25

Aloe vera
Xanthorrhoeaceae)
25

Neocare herbal tea (NHT), Herbalin complex tea (HCT) and Phytoblis herbal tea (PHT).