engleski

Antibacterial Activity of Organic Extracts of Gorgonian Eunicella cavolini from the Adriatic Sea in Croatia

Eunicella cavolini is an abundant gorgonian species in the Mediterranean Sea and previous studies in Greece showed its organic extracts to be rich in complex steroids (pregnanes, epidioxysterols, and secosterols) that showed antiproliferative activity against various human cancer cell lines. This study evaluated antibacterial activity against three human pathogens Escherichia coli (EC), Pseudomonas aeruginosa (PA), and Staphylococcus aureus (SA). Sampling was performed in May 2018 at 23m depth. Specimens were extracted using CH2Cl2/MeOH (3:1) at room temperature, dried in vacuo (OE) with further 4 fractions obtained with c-hexane:EtOAc (2 fractions with 75:25 (F1) and 50:50 (F2) ratio, respectively), EtOAc (F3), and EtOAc:MeOH (80:20 (F4)), all dissolved in DMSO. The highest tested concentrations were 2500 μg/mL for all extracts and 1000 μg/mL for F1. The antibacterial activity was evaluated by broth microdilution assay according to the Clinical & Laboratory Standards Institute guidelines with results interpreted both visually and spectrophotometrically. The results showed partial inhibition of all three bacterial species by the OE with the highest activity against SA which was an order of magnitude higher than with EC and PA. Fractionated samples F1-3 had higher antibacterial activity (in decreasing order F2, F3, F1) than the OE with SA being the most inhibited followed by EC, and PA. Minimum inhibitory concentration (MIC) was observed only for SA with F2 and F3 at the highest tested concentration. Cultivation of SA at MIC showed the fractions with bacteriostatic rather than bactericidal activity, with F2 having the strongest activity according to number of colonies isolated.

biodiscovery ; Eunicella cavolini ; antimicrobial susceptibility testing ; marine natural products

nije evidentirano