Azodyrecins A–C: Azoxides from a Soil-Derived <i>Streptomyces</i> Species
Mario Wibowo, Charlotte H. Gotfredsen, Elisa Sassetti, Jette Melchiorsen, Mads H. Clausen, Lone Gram, Ling Ding
Abstract
Azoxy compounds belong to a small group of natural products sharing a common functional group with the general structure RN = N+(O–)R. Three new azoxides, azodyrecins A–C (1–3), were isolated from a soil-derived Streptomyces sp. strain P8-A2. The cis-alkenyl unit in 1–3 was found to readily isomerize to the trans-congeners (4–6). The structures of the new compounds were determined by detailed spectroscopic (1D/2D NMR) and HRMS data analysis. Azodyrecins belong to a new class of natural azoxy compounds and are proposed to derive from l-alanine and alkylamines. The absolute configurations of 1–6 were defined by comparison of ECD spectra. While no antimicrobial effects were observed for 1 against Staphylococcus aureus, Vibrio anguillarum, or Candida albicans, azodyrecin B (2) exhibited cytotoxicity against the human leukemia cell line HL-60 with an IC50 value of 2.2 μM.