chlorination carbon nuclear magnetic resonance 4 drug isolation 4 drug synthesis 4 proton nuclear magnetic resonance 4 structure activity relation 4 unclassified drug 4 2 amino cycloart 1 en 3 one 2 2 chloro cycloart 1 en 3 one 2 2 hydroxy cycloart 1 en 3 one 2 2,2 dibromo cycloartan 3 one 2 2,2 dichloro cycloartan 3 one 2 2alpha azido cycloartan 3 one 2 2alpha chloro cycloartan 3 one 2 2alpha fluor cycloartan 3 one 2 2beta fluor cycloartan 3 one 2 3 benzoyl cycloart 2 ene 2 6 chloro norharmane 2 6 chloroharmane 2 7 acetylharmol 2 8 chloro norharmane 2 8 chloroharmane 2 Article 2 Cycloartanes 2 Cycloartanone 2 Cytotoxicity 2 IC50 2 MCF-7 cell line 2 Synthetic derivatives 2 Tillandsia 2