Abstract
Ouratea fieldingiana is a native medicinal plant from Northeastern Brazil and many biological properties are due to the phenolic constituents. The objective of this work was performing the characterization of O. fieldingiana leaf constituents to correlate with antioxidant and anticholinesterase activities by in vitro and in silico studies and thus contribute to find new agents against Alzheimer’s disease. The high-performance liquid chromatography revealed the presence of the flavonoids rutin, isoquercitrin, kaempferol-3-O-rutinoside, quercetin, apigenin and amentoflavone. The antioxidant activities by the (2,2-diphenyl-1-picrylhydrazyl) (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) methodologies, showed good results with half maximal inhibitory concentration (IC50) values ranging from 5.63 to 11.47 μg mL-1 and 2.72 to 23.71 μg mL-1, respectively. Acetylcholinesterase inhibition assay pointed out the flavone apigenin with best activity. Computational studies evaluated the interaction of flavonoids with the enzyme acetylcholinesterase co-crystallized with the galantamine, used as standard. All flavonoids exhibited binding energy greater than that of galantamine, but only apigenin showed strong interaction with the active site of the enzyme and other bind probably to different allosteric centers. Then, O. fieldingiana extract and flavonoids with good anti-radical activity and presenting a broad-spectrum action against acetylcholinesterase (AChE) enzyme ought to be tested in clinical studies to discover new neuro-therapeutic candidates.
Highlights
Ouratea fieldingiana (Ocnaceae) is found in the littoral area of Ceará and Rio Grande do Norte States and the plant extracts were considered important source of antioxidants
The computational simulations made with flavonoids from O. fieldingiana and AChE in this study showed their molecular interactions at different sites of activity (Figure 1b), in relation to the two active sites of galantamine in the dimeric structure (Figure 1c)
The results demonstrated that these biologically active flavonoids are able to interact with AChE in active site and allosteric sites, inhibiting the enzymatic action
Summary
Ouratea fieldingiana (Ocnaceae) is found in the littoral area of Ceará and Rio Grande do Norte States and the plant extracts were considered important source of antioxidants. The biflavonoid amentoflavone was found in was evaluated with the open field test. K3R did not alter the fish’s locomotor system and significantly reduced the orofacial nociceptive behavior induced by all noxious agents compared to the control group. The antinociceptive effect of K3R was similar to morphine.[2]. Several fruit plant polyphenols have been confirmed to be neuroprotective agents, including reducing Aβ peptide aggregation. Resveratrol, found in grapes and in cereals, tea and peanuts. Polyphenols like the flavonoid quercetin contributes significantly to the protection of neuronal cells against neurotoxicity caused by oxidative stress.[3]
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