The antibacterial and antibiofilm activity of sea anemone (Stichodactyla haddoni) against antibiotic-resistant bacteria and characterization of bioactive metabolites

Abstract: Sea anemones produce many biologically active compounds including neurotoxins, pore-forming
toxins, phospholipases and proteinase inhibitors. The Persian Gulf is an unexplored environment and maybe a
rich source of marine natural products. The aim of this study is screening and identification of bioactive
metabolites from Stichodactyla haddoni (Haddon’s sea anemone) collected at the Persian Gulf. The crude
extract of the sea anemone (tentacle, disc and total body) was obtained by methanol solvent. The antibacterial
assays were carried out by the disc diffusion method. The antibiofilm activity (biofilm formation, biofilm
destruction and reduction of metabolic activity) of the sea anemone extracts was evaluated by microtiter plate
method. The bioactive compounds were identified by GC–MS analysis. Data showed that the best antibacterial
effect (relate to P. aeruginosa) is obtained from extracts of ‘‘total body’’ section. Values of minimum
inhibitory concentration and minimum bactericidal concentration show that the maximum antibacterial
activity takes place at 10–20 mg/ml concentration. Three parts of sea anemone exhibit different inhibition
against biofilm of bacteria, in particular, inhibition of biofilm observed by the tentacle, disc and total body
against P. aeruginosa, K. pneumonia and A. baumannii, respectively. Biofilm of P. aeruginosa was the most
sensitive and the biofilm of B. cereus was the most resistant structure between all pathogenic bacteria. The
best reduction in the metabolic activity was observed in P. aeruginosa and K. pneumonia among tested
bacteria. Aliphatic compounds were predominant bioactive metabolites in this sea anemone. The marine
animal and especially sea anemone produce useful bioactive compounds that can be used to prevent bacterial
biofilm; application of bioactive materials, reported in this study, can be proposed for future studies.