Antifungal–antiproliferative norcycloartane-type triterpenes from the Red Sea green alga Tydemania expeditionis

Abstract

The current work aims to isolate the bioactive secondary metabolites from the Red Sea green alga T. expeditionis. Its organic extract was partitioned and analyzed using chromatographic and spectroscopic techniques. Four triterpenoids of the cycloartane-carbon skeleton were identified as: 29-norcycloartane-3-en-23,28-diol (1), 29-norcycloartane-5,24-dien-3-ol-23-one (2), 29-norcycloartane-3,24-dien-3-ol-23-one (3), and 29-norcycloartane-5,24-dien-3-ol (4), along with hydroxylated C-18 fatty acid, 3-hydroxyoctadeca-15(Z)-enoic acid (5). The antiproliferative activity of the isolated metabolites was examined against three cancer cell lines, i.e., HeLa, HepG-2, and MCF-7. Compounds 2 and 3 demonstrated a strong antiproliferative effect against all cells with IC50 values ranging from 17.8 ± 1.71 to 23.3 ± 1.66 µM. Compounds 1 and 4 showed a moderate antiproliferative effect against all cell lines with IC50 values ranging from 44.7 ± 2.32 to 65.0 ± 3.66 µM. The antifungal activity of all compounds has been tested against several fungi. Compounds 2–4 revealed strong inhibition against A. flavus and Fusarium oxysporum. Compounds 1–4 showed moderate to weak inhibition activity against A. niger, A. fumigatus, C. albicans, and C. tropicalis. Compound 5 showed weak to non-detected activity against all cell lines and microbes. The results indicated that norcycloartanes exhibit antiproliferative and antifungal activities, especially those with α,β-unsaturated ketones in their side chain.

Keywords

• seaweeds
• chromatographic isolation
• spectroscopy
• antiproliferation
• antifungal