Abstract
Mistletoes are considered to be the potential medicinal herbs due to their rich traditional uses. Loranthus globosus is a Bangladeshi mango mistletoe that has been reported as folk medicine for various ailments and diseases. In an attempt to explore its effectiveness in Alzheimer's disease (AD), we investigated the antioxidant and acetylcholinesterase inhibitory activity of L. globosus. We report that the crude methanol extract (CME) of the plant contains a good amount of polyphenolics and possesses antioxidant and cholinesterase inhibitory activity. Fractionation of CME with solvents of varying polarity revealed the highest activity and polyphenolic content in the ethylacetate fraction (EAF). Correlation analysis revealed a significant (P < 0.05) association of polyphenolics with the antioxidant and cholinesterase inhibitory properties. Using column chromatography with diaion resin, the polyphenolics (EAF-PP) were isolated from the EAF that displayed the potent antioxidant and cholinesterase inhibitory activities. Kinetic analysis showed that EAF-PP exhibited a competitive type of inhibition. A total of thirty-six compounds including catechin and its different derivatives were identified in the EAF-PP by LC/MS analysis. Bioactivity-guided separation approach afforded the isolation of the two major active compounds catechin and catechin dimer from the EAF-PP. Hence, EAF-PP represents a potential source of antioxidants and cholinesterase inhibitors, which can be used in the management of AD.
Highlights
Among the neurodegenerative disorders, Alzheimer’s disease (AD) is the most devastative disorder of the aged people characterized by deficit of memory and cognition, psychobehavioral disturbances, and functional disabilities [1]
Chemicals. 2,2′-Diphenyl-1-picrylhydrazyl (DPPH), 5,5′-dithio-bis-(2-nitro) benzoic acid (DTNB), thiobarbituric acid (TBA), 2-deoxy-D-ribose, acetylthiocholine, Sbutyrylthiocholine, donepezil, and galantamine were procured from Sigma-Aldrich, Germany. silica gel GF264, silica gel 60-120, Folin-Ciocalteu reagent, Tris-HCl, aluminum chloride, potassium ferricyanide, ammonium molybdate, trichloroacetic acid (TCA), and triton X-100 were from Merck, Darmstadt, Germany
The results demonstrated that the crude methanol extract (CME) possesses a good amount of phenolics (336:989 ± 1:837 mg GAE/g dried extract), flavonoids (180:00 ± 2:06 mg GAE/g dried extract), and proanthocyanidin (291:00 ± 1:50 mg GAE/g dried extract)
Summary
AD is the most devastative disorder of the aged people characterized by deficit of memory and cognition, psychobehavioral disturbances, and functional disabilities [1]. A common mechanism observed in the pathological process of neurodegenerative disorders including AD is oxidative stress, which originates due to disruption of balance between the oxidants and antioxidant system [4]. It is increasingly evident that Abeta protein, which is overproduced in AD, can generate ROS and free radicals and leads to peroxidation of lipid in the neuronal membrane [7]. This in turn disrupts the membrane integrity of the neuronal cells and causes cellular dysfunction [8]. Antioxidant therapies have been found to be effective in ameliorating the oxidative damage and improve the memory and cognitive function in the experimental model of AD [9]. Natural antioxidants have attracted intense interest because they are safe and display a diverse biological activity
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