• Natural Product Sciences
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• v.28 no.3
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• pp.138-142
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• 2022

Alzheimer's disease (AD) is the most common age-related neurodegenerative disease in industrialized countries. It is estimated that about 47 million people living with dementia and the number of cases will be tripled by 2050. However, the exact mechanism of AD is not known, and full therapy has still not been found. Various tryptophan-derived alkaloids have been reported as promising agents for the treatment of AD. In the present study, a series of tryptophan-derived alkaloids were isolated and characterized from the methanol extract of Hedera rhombea fruit. Based on the analysis of their observed and reported spectroscopic data, their structures were identified as N-[4'-hydroxy-(E)-cinnamoyl]-L-tryptophan (1), N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tryptophan (2), N-[4'-hydroxy-(E)-cinnamoyl]-L-tryptophan methyl ester (3), and N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tryptophan methyl ester (4). These compounds were screened for anti-Alzheimer activity via their inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes in vitro. As a result, compounds 3 and 4 showed moderate BChE inhibition with IC₅₀ values of 86.9 and 78.4 μM, respectively, compared to those of the positive control [berberine (IC₅₀ = 11.5 μM)]. However, all four compounds did not show significant inhibition of the AChE enzyme. This is the first time, the AChE and BChE inhibitory activities of these tryptophan-derived alkaloids were investigated and reported.

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.135-153
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• 2015

The aromatic amino acids, which are composed of $\small{L}$-phenylalanine, $\small{L}$-tyrosine and $\small{L}$-tryptophan, are general components of protein synthesis as well as precursors for a wide range of secondary metabolites. These aromatic amino acids-derived compounds play important roles as ingredients of diverse phenolics including pigments and cell walls, and hormones like auxin and salicylic acid in plants. Moreover, they also serve as the natural products of alkaloids and glucosinolates, which have a high potential to promote human health and nutrition. The biosynthetic pathways of aromatic amino acids share a chorismate, the common intermediate, which is originated from shikimate pathway. Then, tryptophan is synthesized via anthranilate and the other phenylalanine and tyrosine are synthesized via prephenate, as intermediates. This review reports recent studies about all the enzymatic steps involved in aromatic amino acid biosynthetic pathways and their gene regulation on transcriptional/post-transcriptional levels. Furthermore, results of metabolic engineering are introduced as efforts to improve the production of the aromatic amino acids-derived secondary metabolites in plants.