Cyaneodimycin, a Bioactive Compound Isolated from the Culture of Streptomyces cyaneofuscatus Associated with Lichina confinis

Two new compounds, cyaneodimycin (1) and cyaneomycin (2) bearing a rare methacrylate residue, were isolated from cultures of the bacterium Streptomyces cyaneofuscatus associated with the marine lichen Lichina confinis. These astonishing structures may be derived from a pyruvate biosynthetic pathway. Cyaneodimycin (1) exhibited antiproliferative properties against B16 (IC₅₀= 27 ± 4 µm), HaCaT (IC₅₀= 47 ± 11 µm) and Jurkat cell lines (IC₅₀= 18.5 ± 0.5 µm). Six known compounds 3–8 with diversified structures and interesting biological properties (diketopiperazines, actinomycin, dibenzofurane or indole derivatives) were isolated jointly with compounds 1 and 2. Among them, usnic acid (8), a common lichen compound was isolated for the first time from bacteria.