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Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Betulinic acid derivatives used in this study; for synthesis of BA1 and BA2, see [48]; for synthesis of BA3 and BA4, see [39]. Figure adapted from [48].