Implications of some selected flavonoids towards Alzheimer's disease with the emphasis on cholinesterase inhibition and their bioproduction by metabolic engineering.

Flavonoids are one of the most abundant secondary metabolites having a polyphenolic structure in plant and animal species with various desired pharmacological effects towards human health. Many flavonoid derivatives have been reported to possess neuroprotective activity through different mechanisms of action and, among them, cholinesterase (ChE) inhibition constitutes an important clinically applied treatment strategy of Alzheimer's disease (AD). Some flavonoid derivatives have been demonstrated to inhibit both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) to varying extent, which are called the sister enzymes linked to the pathogenesis of AD. On the other hand, diverse bioproduction techniques such as plant tissue culture, microbial transformation, etc. are applicable for flavonoids and, among them, production of flavonoids through metabolic engineering using special bacteria or yeast species has recently become popular. In the current review, some common flavonoids with ChE inhibitory effect as well as the examples of flavonoids obtained from metabolic engineering methods will be discussed.