. 2017 Jun 27;22(7):1075. doi: 10.3390/molecules22071075
© 2017 by the authors.
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 (http://creativecommons.org/licenses/by/4.0/).
Figure 1.
Structures of betulinic acid and betulin.