Constituents From Brazilian Propolis Against Edwardsiella ictaluri and Flavobacterium covae , Two Bacteria Affecting Channel Catfish ( Ictalurus punctatus )

Abstract

Edwardsiella ictaluri and Flavobacterium covae are two bacteria species that cause diseases in farm‐raised channel catfish ( Ictalurus punctatus ) that cause heavy economic damage to the aquaculture industry, particularly to the channel catfish farming. In search for environmentally benign antibacterial compounds active against E. ictaluri and F. covae , we investigated the constituents isolated from Brazilian red, brown and green propolis. We have also synthetically modified active constituents to see if lipophilicity plays a role in enhancing antibacterial activities. Vestitol, neovestitol and methylvestitol were found to be the active constituents with minimum inhibitory concentration (MIC) relative to drug control florfenicol (RDCF) values (MIC − RDCF) of 7.6, 7.6 and 7.9 mg/L, respectively, against F. covae . The activity against E. ictaluri was not significant.

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