Two New Xeniolide Diterpenes from the Soft Coral Xenia umbellata; Displayed Anti Proliferative Effects

Objective: Xenia is an octocoral genus of family Xeniidae. It contains 98 species and is rich of xenican‑type diterpenoids. These compounds play an important role in the biological activity of Xenia. Different bioactivities were reported, particularly, anticancer effects. Materials and Methods: A specimen of a Xenia umbellata was exhausted with organic solvents. Then, the organic extract has been fractionated and purified employing different chromatographic procedures. The spectral information obtained from different nuclear magnetic resonance experiments, mass spectroscopy, infrared, and ultraviolet was the key to elucidate the chemical structures. The anti‑proliferative activities of all compounds have been evaluated against hepatocellular carcinoma (HepG2), prostate adenocarcinoma (PC‑3), and colorectal adenocarcinoma (HT‑29) cells. Results: Two new xeniolide‑type diterpenes, xeniolide L (1) and xeniolide M (2), along with two known diterpenes, xeniolide K (3) and xeniumbellal (4) were isolated. Compounds 1–4 exhibited significant cytotoxic effect with IC50 values ranged from 0.17 ± 0.01 to 64.7 ± 0.40 µg/mL. Compound 1 displayed late apoptotic and necrotic effects in both HepG2 and PC‑3, while 2 exhibited late apoptosis in HepG2 cells. Conclusion: The isolated xeniolide diterpenes displayed antiproliferative effects against tumor cells (HepG2, PC‑3, and HT‑29). The new compounds showed late apoptotic and necrotic effects in HepG2 cells.