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The present study aimed to screen for antibacterial activities in soft corals of the eastern Red Sea coast. Specimens of different species were surveyed, collected, preserved, extracted and assayed according to standard protocols. Bioactive materials were extracted using a dichloromethane/methanol mixture, and the activity was determined using the well diffusion and microdilution assay methods. All extracts demonstrated variable activity against marine bacteria previously isolated from the sea water (in situ near the soft corals). Among soft corals, Sarcophyton spp. and Sinularia polydactyla showed the highest activity (MIC = 30-50 g/ml), while the crude extract of Xenia spp. showed the lowest activity (MIC = 200-250 g/ml) against the isolated marine bacterial strains.Antibacterial activity was observed for five out of the seven soft coral extracts (72%) against two Gram-positive (Staphylococcus aureus and Bacillus spp.) bacterial pathogens, while none of the extracts inhibited Gram-negative (Escherichia coli) bacteria. The most potent (MIC = 40-75 g/ml) crude extracts were obtained from S. polydactyla and Sarcophyton spp., while the crude extract of Xenia spp. was the least effective (MIC ≥ 200 g/ml) against the tested Gram-positive bacteria. The results from the current study suggest that soft corals of the Red Sea (Yunbu, SA) are a potential source of novel antibiotics.

BackgroundIt is estimated that venoms of marine cone snails (genus Conus) contain more than 100,000 different small peptides with a wide range of pharmacological and biological actions. Some of these peptides were developed into potential therapeutic agents and as molecular tools to understand biological functions of nervous and cardiovascular systems. In this study we examined the cytotoxic and anticancer properties of the marine vermivorous cone snail Conus vexillum (collected from Hurgada and Sharm El-Shaikh, Red Sea, Egypt) and suggest the possible mechanisms involved. The in vitro cytotoxic effects of Conus venom were assessed against Ehrlich’s ascites carcinoma (EAC) cells.ResultsConus venom treatment resulted in concentration-dependent cytotoxicity as indicated by a lactate dehydrogenase leakage assay. Apoptotic effects were measured in vivo by measuring levels of reactive oxygen species and oxidative defense agents in albino mice injected with EAC cells. Conus venom (1.25 mg/kg) induced a significant increase (p < 0.05) in several oxidative stress biomarkers (lipid peroxidation, protein carbonyl content and reactive nitrogen intermediates) of EAC cells after 3, 6, 9 and 12 hours of venom injection. Conus venom significantly reduced (p < 0.05) the activities of oxidative defense enzymes (catalase and superoxide dismutase) as well as the total antioxidant capacity of EAC cells, as evidenced by lowered levels of reduced glutathione.ConclusionsThese results demonstrate the cytotoxic potential of C. vexillum venom by inducing oxidative stress mediated mechanisms in tumor cells and suggest that the venom contains novel molecules with potential anticancer activity.