In Vitro Screening for Acetylcholinesterase Inhibition and Antioxidant Activity of Quercus suber Cork and Corkback Extracts

Abstract

Purpose. Acetylcholinesterase (AChE) inhibitors are used to treat Alzheimer’s patients because they enhance cholinergic neurotransmission. It is urgent to find new and efficient inhibitors from natural sources, highly bioavailable with low or no toxicity. The plant kingdom is extremely rich in a variety of compounds that are potent AChE inhibitors: flavonoids and other phenolic compounds have been recognized as promising Alzheimer’s treatment agents. In this study, in vitro acetylcholinesterase inhibition, antioxidant activities, and total flavonoid and phenolic contents of ethanol-water extracts from Quercus suber cork and corkback were evaluated. Methods. The acetylcholinesterase activity was determined by a colorimetric assay based on Ellman’s methodology. The Folin–Ciocalteu colorimetric method was used for total phenolic content determination and the aluminium chloride method for the determination of total flavonoid content. Antioxidant activity assays were performed using the DPPH and FRAP assays. Results. The acetylcholinesterase inhibitory activity from Q. suber cork and corkback ethanol-water extracts was as follows: 62% inhibition with corkback extracts over 0.5 mg/mL and around 49% inhibition in cork extracts over 1.0 mg/mL extracts’ concentration. Regarding the DPPH radical scavenging activity, the concentrations of cork and corkback ethanol-water extracts required for 50% DPPH inhibition (IC50) were 3.2 μg/mL and 4.0–5.2 μg/mL. Corkback extracts are less effective than Trolox standard (3.2 μg/mL) but cork extracts showed the same free radical scavenging activity compared to Trolox. Cork and corkback extracts have antioxidant power of 750.9–775.4 mg TEAC/g extract and 1051.2–2052.4 mg TEAC/g extract, respectively, which are significantly higher than the ones obtained with Trolox: 19.6–21.0 mg TEAC/g extract (cork assays) and 57.4–66.3 mg TEAC/g extract (corkback assays). The amounts of total phenolic (TPC) and flavonoid (TFC) compounds were 8.7–32.3 mg GAE/g and 4.8–10.7 mg CE/g dry mass for cork and 5.4–5.7 mg GAE/g and 42.5 mg CE/g dry mass for corkback extracts, respectively, using catechin (CE) and GAE (gallic acid) as standards. Conclusion. These findings demonstrate the remarkable potential of these extracts as valuable source of antioxidants with interesting acetylcholinesterase inhibitory activity.

Laccase-Catalyzed Synthesis of Added-Value Polymers from Cork and Grape Extracts

“…These results, together with the phenolic content values, demonstrate the high potential of these products as a source of high-value compounds. These results are promising since cork and grape (ethanol–water) extracts can be used as a source of potential natural antioxidants in nutraceutical applications or material surfacing protection …”

GC-MS Metabolic Profile and α-Glucosidase-, α-Amylase-, Lipase-, and Acetylcholinesterase-Inhibitory Activities of Eight Peach Varieties

“…The serious side effects of synthetic inhibitors have forced the research community to search for natural alternatives. So far, galanthamine, huperzine A, and tacrine have been used for therapy [ 89 ]. Additionally, fruits and vegetables with proven target activities can be included in the daily menus of susceptible subjects.…”

“…The potential of Prunus persica L. water extracts to inhibit AChE effectively was also demonstrated in vivo [ 90 ]. Although it was thought that phenolic compounds are responsible for the inhibitory activity towards this enzyme [ 89 ], Rodríguez-Solana et al [ 91 ] reported a negative correlation (according to Pearson correlation coefficients) in carob liqueurs. Nakagawa et al [ 92 ] found no inhibitory activity of extracts of the peel and flesh of unripe fruits of “Akatsuki” and “Fastigiata” peach varieties.…”

Role of Natural Compounds and Target Enzymes in the Treatment of Alzheimer’s Disease

“…Dihydroberberine and macelignan potently and effectively inhibited AChE with IC50 values of 1.18 and 4.16 µM, respectively [43]. Quercus suber cork and corkback ethanol-water extracts have been proven to be remarkable antioxidants with interesting AChE inhibitory activity [44]. Using the in vitro Ellman's technique, extracts, fractions, and compounds from Calceolaria talcana and Calceolaria integrifolia showed substantial inhibitory effects on AChE activity.…”