Studies on the Red Sea Sponge Haliclona sp. for its Chemical and Cytotoxic Properties

Background: A great number of novel compounds with rich chemical diversity and significant bioactivity have been reported from Red Sea sponges. Objective: To isolate, identify, and evaluate the cytotoxic activity of the chemical constituents of a sponge belonging to genus Haliclona collected from the Eastern coast of the Red Sea. Materials and Methods: The total ethanolic extract of the titled sponge was subjected to intensive chromatographic fractionation and purification guided by cytotoxic bioassay toward various cancer cell lines. The structures of the isolated compounds were elucidated using spectroscopic techniques including one‑dimension and two‑dimension nuclear magnetic resonance, mass spectrometry, ultraviolet, and infrared data, as well as comparison with the reported spectral data for the known compounds. X‑ray single‑crystal structure determination was performed to determine the absolute configuration of compound 4. The screening of antiproliferative activity of the compounds was carried on three tumor cell lines, namely the human cervical cancer (HeLa), human hepatocellular carcinoma (HepG2), and human medulloblastoma (Daoy) cells using MTT assay. Results: This investigation resulted in the isolation of a new indole alkaloid, 1‑(1H‑indol‑3‑yloxy) propan‑2‑ol (1), with the previously synthesized pyrrolidine alkaloid, (2R, 3S, 4R, 5R) pyrrolidine‑(1‑hydroxyethyl)‑3,4‑diol hydrochloride (4), isolated here from a natural source for the first time. In addition, six known compounds tetillapyrone (2), nortetillapyrone (3), 2‑methyl maleimide‑5‑oxime (5), maleimide‑5‑oxime (6), 5‑(hydroxymethyl) dihydrofuran‑2 (3H)‑one (7), and ergosta‑5,24 (28)‑dien‑3‑ol (8) were also identified. Most of the isolated compounds exhibited weak cytotoxic activity against HepG‑2, Daoy, and HeLa cancer cell lines. Conclusion: This is the first report of the occurrence of the indole and pyrrolidine alkaloids, 1‑(1H‑indol‑2‑yloxy) propan‑2‑ol (1), and the ‑ (1‑hydroxyethyl)‑3,4‑diol hydrochloride (4), in the Red Sea Haliclona sp.