Synthesis and Biological Evaluation of Flavonoid‐Cinnamic Acid Amide Hybrids with Distinct Activity against Neurodegeneration in Vitro and in Vivo

• Published in: Chemistry : a European journal Vol. 28; no. 39; pp. e202200786 - n/a
• Main Authors: Hofmann, Julian, Spatz, Philipp, Walther, Rasmus, Gutmann, Marcus, Maurice, Tangui, Decker, Michael
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 11-07-2022; Wiley-VCH Verlag; John Wiley and Sons Inc
• Subjects: Acids; AD mouse modele; Alzheimer's diseas; Alzheimer's disease; Chemistry; Cinnamic acid; Depletion; Ferroptosis; Flavonoids; Hippocampus; Hybridization; Hybrids; Hydrolysis; Life Sciences; Metabolites; natural product hybrids; Natural products; Neurodegeneration; Neurodegenerative diseases; Neuroprotection; oxytosis/ferroptosis; Quercetin; Silibinin; AD mouse modele; Alzheimer's diseas; natural product hybrids; oxytosis/ferroptosis
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202200786

Flavonoids are polyphenolic natural products and have shown significant potential as disease‐modifying agents against neurodegenerative disorders like Alzheimer's disease (AD), with activities even in vivo. Hybridization of the natural products taxifolin and silibinin with cinnamic acid led to an overadditive effect of these compounds in several phenotypic screening assays related to neurodegeneration and AD. Therefore, we have exchanged the flavonoid part of the hybrids with different flavonoids, which show higher efficacy than taxifolin or silibinin, to improve the activity of the respective hybrids. Chemical connection between the flavonoid and cinnamic acid was realized by an amide instead of a labile ester bond to improve stability towards hydrolysis. To investigate the influence of a double bond at the C‐ring of the flavonoid, the dehydro analogues of the respective hybrids were also synthesized. All compounds obtained show neuroprotection against oxytosis, ferroptosis and ATP‐depletion, respectively, in the murine hippocampal cell line HT22. Interestingly, the taxifolin and the quercetin derivatives are the most active compounds, whereby the quercetin derivate shows even more pronounced activity than the taxifolin one in all assays applied. As aimed for, no hydrolysis product was found in cellular uptake experiments after 4 h whereas different metabolites were detected. Furthermore, the quercetin‐cinnamic acid amide showed pronounced activity in an in vivo AD mouse model at a remarkably low dose of 0.3 mg/kg.
Flavonoid‐cinnamic acid amides were synthesized and evaluated in phenotypic screening assays related to neurodegeneration. The compounds prevent cell death in models of oxidative stress and energy breakdown. The introduction of an amide yielded higher stability towards hydrolysis and altering the flavonoid core structure showed that the quercetin‐cinnamic acid amide hybrid was the most potent compound, and its in vitro properties could be translated into high activity in an in vivo AD mouse model.