METHODS: In the present research, Aspergillus unguis, an endophytic fungal strain derived from the marine sponge A. suberitoides was successfully isolated and characterized. Subsequently, ethyl acetate extraction and isolation of chemical constituents produced was performed. The structures of the isolated compounds were identified using several spectroscopic methods, ie, UV, NMR, and mass spectrometry. Thereafter, MDA-MB-231, MCF-7 breast cancer cells and HaCat cells were treated with the isolated compounds. Not only viability, apoptosis, and cell cycle analyses were conducted, but also the mRNA expression of MCL1, BCL2L1, AKT1 and CDK2 were evaluated.

RESULTS: The extract showed cytotoxic activity in breast cancer cells. Two novel compounds were successfully isolated and identified, ie, Unguisol A (15.1 mg) and Unguisol B (97.9 mg). Both compounds share the same basic skeleton and comprise an aromatic ring which is attached to a sulphur-containing, seven-membered ring via an oxygen atom. This marked the first-time isolation of Unguisol A and Unguisol B from A. unguis, highlighting their novelty. Both compounds induced early apoptosis (p < 0.01) and cell cycle arrest at the S phase (p < 0.05) in MDA-MB-231 cells, but not in HaCat cells. Both compounds suppressed BCL2L1 and AKT1 mRNA expression (p < 0.01).