Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Chemical structures of tylophorine-based alkaloids. (A) Phenanthroindolizidine skeleton, containing a highly oxygenated phenanthrene group fused with an indolizidine group. (B) Tylophorine and its phenanthroindolizidine derivatives. (C) Phenanthroquinolizidine skeleton, containing a highly oxygenated phenanthrene group fused with an indolizidine one. (D) Phenanthroquinolizidine alkaloids (drawn by ChemSketch, ACD Labs Version 12.0).
