Albusamides A–G: Hydroxylated Fatty Amine Derivatives from the Deep-Sea-Derived Actinomycete <i>Streptomyces albus</i> 228DD-066 and Their Cytotoxic Activity

A series of new hydroxylated fatty amine derivatives, albusamides A-G (<b>1</b>-<b>7</b>), along with four known compounds (<b>8</b>-<b>11</b>), which are reported for the first time from a natural source, were isolated from the culture broth of <i>Streptomyces albus</i> 228DD-066 derived from a deep-sea sediment sample gathered off the coast of Dokdo Island, Republic of Korea. Their structures were elucidated through the comprehensive analysis of 1D and 2D NMR spectra and HRESIMS, and absolute configurations were determined using the modified Mosher's method. Biological evaluations against solid and blood cancer cell lines revealed that these new metabolites have moderate to strong cytotoxic activity. Compound <b>3</b> exhibited high cytotoxic activity with GI₅₀ values ranging from 0.4 to 0.6 μM against solid cancer cell lines and exhibited the strongest cytotoxicity (GI₅₀ value = 0.2 μM) against the WSU-DLCL2 blood cancer cell line.