Precursor-Directed Biosynthesis Mediated Amplification of Minor Aza Phenylpropanoid Piperazines in an Australian Marine Fish-Gut-Derived Fungus, sp. CMB-F214.

Chemical analysis of an M1 agar plate cultivation of a marine fish-gut-derived fungus, sp. CMB-F214, revealed the known chrysosporazines A-D (-) in addition to a suite of very minor analogues -. A microbioreactor (MATRIX) cultivation profiling analysis failed to deliver cultivation conditions that significantly improved the yields of -; however, it did reveal that M2 agar cultivation produced the new natural product . A precursor-directed biosynthesis strategy adopting supplementation of a CMB-F214 M1 solid agar culture with sodium nicotinate enhanced production of otherwise inaccessible azachrysposorazines A1 (), A2 (), B1 (), C1 (), C2 () and D1 (), in addition to four new chrysosporazines; chrysosporazines N-P (-) and spirochrysosporazine A (). Structures inclusive of absolute configurations were assigned to - based on detailed spectroscopic and chemical analyses, and biosynthetic considerations. Non-cytotoxic to human carcinoma cells, azachrysosporazies - were capable of reversing doxorubicin resistance in P-glycoprotein (P-gp)-overexpressing human colon carcinoma cells (SW620 Ad300), with optimum activity exhibited by the C-2' substituted analogues -.