Cembrene Diterpenoids with Ether Linkages from Sarcophyton ehrenbergi: An Anti-Proliferation and Molecular-Docking Assessment.

Three new cembrene diterpenoids, sarcoehrenbergilid A-C (-), along with four known diterpenoids, sarcophine (), (+)-7α,8β-dihydroxydeepoxysarcophine (), sinulolide A (), and sinulolide B (), and one steroid, sardisterol (), were isolated and characterized from a solvent extract of the Red Sea soft coral . Chemical structures were elucidated by NMR and MS analyses with absolute stereochemistry determined by X-ray analysis. Since these isolated cembrene diterpenes contained 10 or more carbons in a large flexible ring, conformer stabilities were examined based on density functional theory calculations. Anti-proliferative activities for - were evaluated against three human tumor cell lines of different origins including the: lung (A549), colon (Caco-2), and liver (HepG2). Sardisterol () was the most potent of the metabolites isolated with an IC of 27.3 µM against the A549 cell line. Since an elevated human-cancer occurrence is associated with an aberrant receptor function for the epidermal growth factor receptor (EGFR), molecular docking studies were used to examine preferential metabolite interactions/binding and probe the mode-of-action for metabolite-anti tumor activity.