International Science Community Association International Research Journal of Biological Sciences 2278-3202 10 1 2021 02 10 Antioxidant, Antibacterial and Cytotoxic Potential of Selected Macroalgae from the Red Sea, Sudan Coast 19 27 EN Shiferaw Legesse 1 Ethiopia Meat and Dairy Industry Development Institute, P.O.1573, Bishoftu, Ethiopia Damise Taye 2 Selale University, College Animal and Range science, P.O. 245, Fiche, Ethiopia Mahajan Minakshi 1 Department of Botany, Fergusson College, Pune-411004, India Hajare Shweta D. 2 Department of Botany, Fergusson College, Pune-411004, India . Riya 1 Biotechnology, School of Pharmaceutical and Health care Sciences, CT University, Ludhiana, India Thapar Parul 2 Biotechnology, School of Pharmaceutical and Health care Sciences, CT University, Ludhiana, India E.E. El Nur 1 Department of Botany, Faculty of Science, University of Khartoum, PC, 11115, P. O. Box 321 Khartoum, Sudan L.I. Ali 2 Department of Botany, Faculty of Science, University of Khartoum, PC, 11115, P. O. Box 321 Khartoum, Sudan E. Fadul 3 Department of Medicinal Biochemistry, Medicinal, Aromatic and Traditional Research Institute (M.A.P.R.I.), National Center for Research, P. O. Box 2404 Khartoum, Sudan l.E. Mohamed 4 Department of Botany, Faculty of Science, University of Khartoum, PC, 11115, P. O. Box 321 Khartoum, Sudan > Research Paper 2020 7 11 2021 02 10 Marine biodiversity is a source of unique chemical hits with its potential to develop into drug leads. Many studies have reported that macroalgae from marine is considered as an essential origin of antibacterial, antioxidant and antitumor agents. In this study, three marine macroalgae, Jania rubens, Halimeda tuna and Turbinaria decurrens were collected from the Red Sea, Sudan coast near to Port Sudan city. The collected algae were successively extracted using four solvents with increasing polarities. Extracts of the marine macroalgae were evaluated for secondary phytochemicals as well as antioxidant and antibacterial activities using Iron chelating assay and cup plate agar diffusion methods respectively. Dichloromethane crude extracts of J. rubens and T. decurrens were tested for cytotoxic activity.The most bioactive extracts were subjected to column chromatography. Then the fractions evaluated for antioxidant and antibacterial activities. The results revealed that, the algal extracts contained major groups of secondary metabolites; flavonoids, triterpenes and alkaloids. The antioxidant results showed that the chloroform and ethanol extracts of J. rubens and H. tuna were more active than those of the ethyl acetate and the petroleum ether ones (highest activity 86%). The highest positive antibacterial activity were recorded for ethanol extracts against S. aureus and E. coli; while the chloroform extract exhibited positive results against E. coli in all investigated extracts. The fractions indicated that some fractions of the three algae have moderate to low activity against E. coli. J. rubens revealed unprecedented cytotoxic activity with IC50 less than 3µg/ml and selectivity against two of six tumor cell line. A major compound was isolated in pure form using preparative thin layer chromatography. The isolated pure compound was identified as & Copyright@ International Science Community Association