Arachidic acid is a long-chain saturated fatty acid that has been found in peanut butter and anaerobic fungi. [1][2] It inhibits rabbit neutrophil aggregation induced by N-formyl-methionyl-leucyl-phenylalanine when used at a concentration of 5 μM. [3] Formulations containing arachidic acid have been used as surfactants in the manufacture of soaps and cosmetics.

Reference:
[1]. Negoita, M., Mihai, A.L., Adascalului, A., et al. Comparison of the fatty acid composition of peanut butter by applying different fat extraction procedures. Rev. Chim. (Bucharest) 69(11), 3023-3032 (2018).
[2]. Koppová, I., Novotná, Z., Strosová, L., et al. Analysis of fatty acid composition of anaerobic rumen fungi. Folia Microbiol. (Praha) 53(3), 217-220 (2008).
[3]. Naccache, P.H., Moiski, T.F., Volpi, M., et al. Modulation of rabbit neutrophil aggregation and degranulation by free fatty acids. J. Leukoc. Biol. 36(3), 333-340 (1984).