Four new pyran-based cembranoidal diterpenes (1-4) were isolated from the Red Sea softbodied coral Sarcophyton glaucum. Sarcoglauphine A (1) and B (2) are conformers with respect to the dihedral angle between H-7 and the pair of H-6a, 6b, while sarcotrocheliol-B acetate (3) and sarcotrochelione (4) are bicyclic cembranoids. The chemical structures of the isolated compounds were elucidated using spectroscopic methods. The cytotoxicity of the isolated compounds were evaluated against HepG2, MCF-7, and HCT116 cell lines by employing Sulforhodamine B (SRB) method. Compounds 1 and 2 showed significant activities toward HCT116.