Holothurians antifungal and antibacterial activity to human pathogens in the Persian Gulf

Summary Pharmaceutical industries now accept that oceans contain a vast array of organisms with unique biological properties. As investigation of antimicrobial activity, three species of Holothuria sea cucumbers ( Holothuria scabra , Holothuria parva and Holothuria leucospilota ) from the Persian Gulf, Iran, were obtained, their different organs: gonads (G), body wall (BW), intestine tract (IT), respiratory tree (RT) were isolated and extracted with organic solvents: ethyl acetate and methanol. Antifungal and antibacterial activities of each fraction was estimated with a minimum inhibitory concentration (MIC) and disk-diffusion method against the number (i.e. n  = 10) of human pathogenic microbes (eight pathogenic Gram-positive/negative bacteria strains and two fungi). All the sea cucumbers extracts confirmed their strong potential antagonistic effect against the bacterial and fungal indicators, except for three relatively resistant microbial strains: Candida albicans and Pseudomonas aeruginosa and Klebsiella pneumonia. Most effective antifungal and antibacterial activities were recorded for methanolic extract of intestine tract organs of H .  parva against Saccharomyces cerevisiae (MIC = 0.09 mg/ml, IZ = 22 ± 0.8 mm) and Staphylococcus epidermidis (MIC = 0.04 mg/ml and IZ = 30 ± 0.9 mm), compared the other extracts. Nevertheless, the differences between species can result from a variety of their natural habits. The finding suggests that marine Holothuria sea cucumber specie, especially H .  parva , has a potential source for the discovery of natural antibiotic compounds and drug development.