Antimicrobial activity of organic extracts isolated from Aplysina fistularis (Demospongiae : Aplysinidae)

Organic extracts of the sponge Aplysina fistularis (Pallas 1766) were teste d for antimicrobial activity against Cram positive bacteria (Staphylococcus aureus) and Gram negative bacteria (Escherichia coli, Klebsiella pneumonia e and Pseudomonas aeruginosa). The minimal inhibitory concentration (MIC) a nd toxic activity of extract were determined. Susceptibility trials of orga nic fractions obtained by VLC: Hexane, EtOAc and CHCl3 showed that EtOAc fr action has antibacterial activity against E. coli, while CHCl3 fraction inh ibited E. coli and S. aureus growth. The later refractioning of EtOAc fract ion and the biodirected assays showed that fractions F12 and F13 of EtOAc/H ex and EtOAc F14 were bioactive against Gram positive and Gram negative bac teria. Only EtOAc/MeOH Sf(2) from subfractionig of EtOAc F14 produced inhib ition for E. coli and S. aureus. In Sf2 EtOAc/MeOH, MIC was moderate for S. aureus (MIC > 256 g/ml). F4 CHCl3/MeOH produced a high inhibition in S. au reus (MIC = 0.125 g/ml) and for E. coli (MIC > 16 g/ml). F10 CHCl3/MeOH sho wed a moderate activity against S. aureus (MIC > 128 g/ml) and low activity against E. coli (MIC = 512 g/ml). F10 CHCL3/MeOH did no present toxic acti vity against Artemia salina. The fractions F4 CHCL3/MeOH and Sa EtOAc/MeOH were toxic for this organism when the concentration was higher than 100 mug /ml. LC50 in both cases was 548.4 and 243.4 mug/ml respectively. Secondary metabolites of medium polarity obtained from A. fistularis have a wide spec trum of anti bacterial activity. Toxicity analysis suggests that only F10 C HCL3/MeOH has potential as an antimicrobial agent for clinical use.