. 2022 Jan 31;27(3):959. doi: 10.3390/molecules27030959
© 2022 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 (https://creativecommons.org/licenses/by/4.0/).
Figure 1.
Core rings A, B, C, D, and E found in PCTTs.