Abstract

Diethyl ether, acetone and ethanol extracts of ten marine macroalgae; two belonging to Chlorophyceae (Ulva lactuca and Caulerpa racemosa), two belonging to Rhodophyceae (Acanthophora spicifera and Galaxaura elongata) and six taxa belonging to Phaeophyceae (Liagora farinosa, Cystoseira compressa, Cystoseira myrica, Hydroclathrus clathratus, Turbinaria ornata and Padina pavonia) isolated from the inter tidal zone along Qusier Marsa-Alam seashore (Red Sea), Egypt, were evaluated for their antibacterial, antifungal and antiviral activities against 3 Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus and Sarcina maxima), 3 Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumonia), one unicellular (Candida albicans) and two filamentous fungi (Aspergillus flavus and Fusarium oxysporum) and against the Newcastle sense Virus (NDV)-(Paramyxoviridae) which is responsible for acute respiratory distress in chicken. Data showed that some extracts recorded strong inhibitory activities than the reference antibiotics, while others were with moderate and/or week inhibitory activities. However, many were without any inhibitory effects. The cytotoxicity effect of the tested algal extracts on chicken embryo showed that both diethyl ether and acetone extracts had toxic effects, but the ethanol extracts had no toxic effect, so that the ethanol extract was considered to be the most suitable for further studies. The antiviral activities of the ethanol extracts against NDV (Newcastle disease virus) showed that seven of the ten tested algal extracts have strong activities against NDV.

Key words: Antimicrobial and antiviral activities, Newcastle disease virus (NDV), marine macroalgae, Qusier and Marsa-Alam, Red Sea, Egypt.