Abstract Anacardic acid, 2‐hydroxy‐6‐[(8Z,11Z‐pentadeca‐8,11,14‐trienyl]‐benzoic acid, extracted from cashew nut shell liquid (CNSL), has been structurally modified to obtain the 2‐(O‐carboxymethyl)‐6‐[(8Z,11Z)‐pentadeca‐8,11,14‐trienyl]‐benzoic acid and its disodium carboxylate salt. Our separation method allows to easily obtain anacardic acid, which has been of interest for the fabrication of green products. These methods proposed for the first time to synthesize these derivatives are short and cheap, and with a high yield. The elucidation of its structure was carried out by means of infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) techniques. Interfacial rheology properties of surfactant‐air‐water and surfactant‐heptane‐water systems were determined by using a new oscillating spinning drop rheometer apparatus. Physicochemical characterization was performed with a salinity scan in a surfactant‐heptane‐brine system, obtaining a value of the surfactant characteristic parameter σ = −4.3 for the disodium salt and a critical micellar concentration (cmc) of 0.08 wt%, showing high surface activity. The biological activity of both compounds was determined and measurements of their potential antimicrobial activity against Gram‐positive and Gram‐negative bacteria were performed, exhibiting high effectiveness, especially for the disodium salt against Gram‐positive bacteria.