Antioxidant and anticholinesterase activities of amentoflavone isolated from Ouratea fieldingiana (Gardner) Engl. through in vitro and chemical-quantum studies.

ABSTRACT

Ouratea fieldingiana, popularly known as batiputá, is a tree species easily found in the coastal part of northeastern Brazil. Its leaves are rich in biflavonoids, its major compound being amentoflavone. Biflavonoids are well studied due to their high antioxidant capacity. Alzheimer's disease (AD) is a disease characterized by the progressive loss of neurons. Currently, the pharmacological treatment of AD has four drugs donepezil, galantamine, rivastigmine and memantine. Where these drugs, with the exception of memantine, are inhibitors of acetylcholinesterase, thus inhibiting the enzyme that destroys acetylcholine, thus increasing the availability of this neurotransmitter. This article aims to determine in vitro and in silico the antioxidant and anticholinesterase action of amentoflavone isolated from the leaves of Ouratea fieldingiana. The antioxidant capacity of amentoflavone was evaluated using the DPPH* free radical scavenging method, with an IC50 of 5.73 ± 0.08 µg/mL. The antiradical properties of the molecule were also studied in silico through several HAT, SET-PT and SPLET mechanisms via DFT M06-2X/6-311++G(d,p). It was found that in the hydrogen atom transfer mechanism (HAT) the best trend was obtained as an anti-radical mechanism. Amentoflavone has the ability to inhibit acetylcholinesterase when tested in vitro, having an IC50 of 8.68 ± 0.73 µg/mL, corroborating its effect in the in silico test, presenting four strong covalent hydrogen bonds for having a bond length up to 2.5 Å. Thus, amentoflavone is an important target for further testing against Alzheimer's disease. Communicated by Ramaswamy H. Sarma.