TY - JOUR
T1 - Discovery of Tricyclic Clerodane Diterpenes as Sarco/Endoplasmic Reticulum Ca2+-ATPase Inhibitors and Structure-Activity Relationships
AU - De Ford, Christian
AU - Calderón, Carlos
AU - Sehgal, Pankaj
AU - Fedosova, Natalya U.
AU - Murillo, Renato
AU - Olesen, Claus
AU - Nissen, Poul
AU - Møller, Jesper V.
AU - Merfort, Irmgard
PY - 2015/6/26
Y1 - 2015/6/26
N2 - Tricyclic clerodane diterpenes (TCDs) are natural compounds that often show potent cytotoxicity for cancer cells, but their mode of action remains elusive. A computationally based similarity search (CDRUG), combined with principal component analysis (ChemGPS-NP) and docking calculations (GOLD 5.2), suggested TCDs to be inhibitors of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump, which is also the target of the sesquiterpene lactone thapsigargin. Biochemical studies were performed with 11 TCDs on purified rabbit skeletal muscle sarcoplasmic reticulum membranes, which are highly enriched with the SERCA1a isoform. Casearborin D (2) exhibited the highest affinity, with a KD value of 2 μM and giving rise to complete inhibition of SERCA1a activity. Structure-activity relationships revealed that functionalization of two acyl side chains (R1 and R4) and the hydrophobicity imparted by the aliphatic chain at C-9, as well as a C-3,C-4 double bond, play crucial roles for inhibitory activity. Docking studies also suggested that hydrophobic interactions in the binding site, especially with Phe256 and Phe834, may be important for a strong inhibitory activity of the TCDs. In conclusion, a novel class of SERCA inhibitory compounds is presented.
AB - Tricyclic clerodane diterpenes (TCDs) are natural compounds that often show potent cytotoxicity for cancer cells, but their mode of action remains elusive. A computationally based similarity search (CDRUG), combined with principal component analysis (ChemGPS-NP) and docking calculations (GOLD 5.2), suggested TCDs to be inhibitors of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump, which is also the target of the sesquiterpene lactone thapsigargin. Biochemical studies were performed with 11 TCDs on purified rabbit skeletal muscle sarcoplasmic reticulum membranes, which are highly enriched with the SERCA1a isoform. Casearborin D (2) exhibited the highest affinity, with a KD value of 2 μM and giving rise to complete inhibition of SERCA1a activity. Structure-activity relationships revealed that functionalization of two acyl side chains (R1 and R4) and the hydrophobicity imparted by the aliphatic chain at C-9, as well as a C-3,C-4 double bond, play crucial roles for inhibitory activity. Docking studies also suggested that hydrophobic interactions in the binding site, especially with Phe256 and Phe834, may be important for a strong inhibitory activity of the TCDs. In conclusion, a novel class of SERCA inhibitory compounds is presented.
UR - http://www.scopus.com/inward/record.url?scp=84933044544&partnerID=8YFLogxK
U2 - 10.1021/acs.jnatprod.5b00062
DO - 10.1021/acs.jnatprod.5b00062
M3 - Journal article
C2 - 25993619
AN - SCOPUS:84933044544
SN - 0163-3864
VL - 78
SP - 1262
EP - 1270
JO - Journal of Natural Products
JF - Journal of Natural Products
IS - 6
ER -