Saccharopolytide A, a new cyclic tetrapeptide with rare 4-hydroxy-proline moieties from the deep-sea derived actinomycete Saccharopolyspora cebuensis MCCC 1A09850.

A genome mining analysis on the deep-sea derived actinomycete Saccharopolyspora cebuensis MCCC 1A09850 indicated its potential to produce polypeptides. Accordingly, a systematic chemical investigation was conducted, which resulted in the isolation of one new cyclic tetrapeptide (saccharopolytide A, 1) and two known polyketides (2, 3) along with six other miscellaneous compounds (4‒9). Mainly by analysis of the 1D, 2D NMR and MS data, the chemical structure of saccharopolytide A was established as cyclo-(l-Leu-4-hydroxy-l-Pro-l-Phe-4-hydroxy-l-Pro). All isolates were evaluated for anti-allergic and anti-tumor bioactivities. Indol-3-carbaldehyde (4) showed weak anti-allergic effect with IC value of 55.75 μg/mL. And 2 showed weak anti-proliferative activity against Hela and H1299 tumor cell lines. Our results consolidate the potential of deep-sea-derived microorganisms to produce structurally interesting compounds.