English abstract
Soft corals are sedentary animals that lack mechanical defense but evolved sophisticated chemical defense. In our study we collected six dominant soft coral species from Bandar Al-Khayran region (Sultanate of Oman) and tested bioactivity of their methanol: chloroform (1:1) extracts against biofouling and pathogenic bacteria using the disc diffusion method. The soft coral species were identified as Sarcophyto sp.1 and sp.2, Cladiella sp., Scleronephthya sp. and Dendronephthya sp. All tested extracts had some activity against human pathogens, while the highest antimicrobial activity was observed for the extracts of Sinularia sp.1 and Cladiella sp. The crude extract of Scleronephthya sp. has shown activity against Escherichia coli resistant to streptomycin. Only the ethyl acetate extract of Cladiella sp. showed considerable activity against the marine biofouling bacterium Bacillus sp. The antifouling compound from this extract was purified and identified as hydroxytritriacontanoic acid, Comparison of the soft coral extracts revealed that composition of the extracts was highly different in different species and there was no correlation between bioactivity of the coral extracts (number of species inhibited) and the chemical complexity of the extracts (number of non-polar compounds present). This investigation is the first study of the marine natural products in Sultanate of Oman and it showed high potential of soft corals from Oman as a source of biologically active natural products that can be used in industry and pharmacology.
