In‐vitro Anticholinesterases Screening and antioxidant activity of three standardized herbal products used in ethnomedicine of South‐East Nigeria

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 % (IC 50 = 324 μg/ml); HCT and PHT demonstrate 73.77 (IC 50 = 0.2 μg/ml) and 60.6 % (IC 50 = 0.7 μg/ml) respectively compared to eserine with AChE inhibition of 148.26% (IC 50 = 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 IC 50 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 1 Name of Standardized Herbal products, components and yield of methanolic extractS/No. Names of Herbal product Constituents/Common name Family Composition (%) Yield (%)1 Neocare herbal tea4.22NHT (9a)Alcornea cordifolia (Christmas bush) Euphurbiaceae 25Azadirachta indica (Neem leaves) Meliaceae 25Pteridium acquilinum (Fern) Dennstaedtiaceae. 502 Herbalin complex5.52%HCT 10aHippocratea volubilis (Hepocreatea pollens) Hippocreateaceae 50Viscum album Santalaceae 25Thymus pulegiodes (Mother thyme) Meliaceae 253. Phytoblis herbal tea5.24%PHT 1 laUrtica dioica (Stinging nettles) Urticaceae 25Hippocratea volubilis (Hepocreatea pollens) Hippocreateaceae 50Thymus vulgaris (thyme) Meliaceae 25Aloe vera Xanthorrhoeaceae) 25Neocare herbal tea (NHT), Herbalin complex tea (HCT) and Phytoblis herbal tea (PHT).