Synthesis of Water-Soluble Ester-Linked Ursolic Acid–Gallic Acid Hybrids with Various Hydrolytic Stabilities
Synthetic Communications 2021
S.A Popov, C Wang, Z Qi, E.E Shults, Māris Turks

To obtain derivatives of ursolic acid with improved water solubility and antioxidant activity, new ester-linked hybrids of ursolic acid and gallic acid were synthesized. In the reaction of methyl gallate with ursoloyl chloride acetate, both mono- and diacylation products were obtained. To prepare mono-alkylated and mono-acylated derivatives of gallic acid, 4,5-O-methoxymethylene-protected methyl gallate was used. It was found that ursolic-gallic acid hybrids containing phenolic ester linkage readily underwent hydrolysis at C-28 of triterpenoid. The dioxolane protection allowed selective hydrolysis of the methyl ester at the aromatic moiety of the hybrid compound leaving intact the labile C-28 ester at the triterpenoid moiety. The hybrids possessing an ester–ether linker (terpenoid-COO–CH2CH2–O-aryl) are stable to the hydrolysis. The majority of the obtained ursolic–gallic acid hybrids containing free phenolic hydroxyl groups possess excellent antioxidant activity. Notable water solubilities (∼0.5 mg/mL) of novel hybrids containing both carboxyl group and hydroxyls at aromatic moiety were found.


Keywords
antioxidant | ester-type hybrids | gallic acid | Ursolic acid | water solubility
DOI
10.1080/00397911.2021.1939057
Hyperlink
https://www.tandfonline.com/doi/full/10.1080/00397911.2021.1939057

Popov, S., Wang, C., Qi, Z., Shults, E., Turks, M. Synthesis of Water-Soluble Ester-Linked Ursolic Acid–Gallic Acid Hybrids with Various Hydrolytic Stabilities. Synthetic Communications, 2021, Vol. 51, No. 16, pp.2466-2477. ISSN 0039-7911. Available from: doi:10.1080/00397911.2021.1939057

Publication language
English (en)
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