Bioprospecting Anticancer Compounds from the Marine-Derived Actinobacteria Actinomadura sp. Collected at the Saint Peter and Saint Paul Archipelago (Brazil)

The actinomycete strain BRA 177 was recovered from sediment samples collected at the St. Peter and St. Paul Archipelago, Brazil. This work accessed the ability of this strain, identified as Actinomadura sp., to produce bioactive metabolites by exploring the genome and characterizing chemistry and cytotoxicity of isolated compounds. From the crude ethyl acetate extract, the pigments nonylprodigiosin, cyclononylprodigiosin and methylcyclooctilprodigiosin were isolated and displayed cytotoxicity against human tumor and non-tumor cell lines. Sequencing, assembling and prospection of BRA 177 draft genome led to identification of two contigs encoding enzymes with high homology to those from prodiginine biosynthetic gene clusters (BGC) in actinomycetes. Further, Actinomadura sp. BGC presented unique putatives RedJ thioesterase and RedL-like type I PKS, involved on selection of prodiginine biosynthetic fatty acyl precursor, and RedG-like Rieske oxygenase, key for cyclization of the prodiginines, suggesting that cyclononilprodigiosin and methylcyclooctylprodigiosin could actually be considered chemical signatures of Actinomadura spp.