Bulbiferates A and B: Antibacterial Acetamidohydroxybenzoates from a Marine Proteobacterium, <i>Microbulbifer</i> sp.

Abstract

Here we report the discovery of two new 3-acetamido-4-hydroxybenzoate esters, bulbiferates A (1) and B (2), isolated from Microbulbifer sp. cultivated from the marine tunicate Ecteinascidia turbinata. The structures of 1 and 2 were determined by analysis of 2D NMR and MS data. Additionally, three synthetic analogues (3–5), differing in ester sizes/lengths, were prepared for the purposes of evaluating potential structure–activity relationships; no clear correlations tying ester lengths to activity were evident. Bulbiferates A (1) and B (2) demonstrated antibacterial activity against both Escherichia coli (E. coli) and methicillin-sensitive Staphylococcus aureus (MSSA), whereas the synthetic analogues 3 and 4 displayed activity only against MSSA.