New Sesterterpenes from the Antarctic Sponge Suberites sp.

Chemical investigation of the Antarctic sponge Suberites sp. has previously led to the identification of new suberitane derivatives, some of which show bioactivity toward respiratory syncytial virus (RSV). Our ongoing NMR-guided investigation of new specimens of the sponge resulted in the isolation of five new analogs (1–5), previously reported suberitenones A–D (6–9), and oxaspirosuberitenone (10). Suberitenone K (1) was characterized as the 8-keto derivative of 6, while three new phenols, suberitandiol (2), abeosuberitandiol (3), and furanosuberitandiol (4), and the degraded sesterterpene norsuberitenone B (5) were also found. Compound 3 displays a ring contraction while 4 has a new dihydrofuran ring. Structural characterization was achieved by a combination of NMR, HR-MS, and X-ray diffraction (XRD). Moderate activity towards RSV was reported for 9 and the new metabolite 1, with IC50 values of 15.0 μM and 39.8 μM, respectively.

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