Tanzania Journal of Science 44(2): 104-116, 2018 ISSN 0856-1761, e-ISSN 2507-7961 © College of Natural and Applied Sciences, University of Dar es Salaam, 2018 104 www.tjs.udsm.ac.tz www.ajol.info/index.php/tjs/ BIOACTIVITIES OF EXTRACTS, DEBROMOLAURINTEROL AND FUCOSTEROL FROM MACROALGAE SPECIES Sartaz Begum 1 , Stephen S. Nyandoro* 1 , Amelia S. Buriyo 2 , John J. Makangara 3 , Joan J. E. Munissi 1 , Sandra Duffy 4 , Vicky M. Avery 4 and Mate Erdelyi 5,6 1 Chemistry Department, College of Natural and Applied Sciences, University of Dar es Salaam, P.O. Box 35061, Dar es Salaam, Tanzania 2 Botany Department, College of Natural and Applied Sciences, University of Dar es Salaam, P.O. Box 35060, Dar es Salaam, Tanzania 3 Chemistry Department, College of Natural and Mathematical Sciences, The University of Dodoma, P.O. Box 338, Dodoma, Tanzania 4 Discovery Biology, Eskitis Institute for Drug Discovery, Gri ffith University, Nathan, Q1d 4111, Australia 5 Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg SE-412 96, Sweden 6 Swedish NMR Centre, University of Gothenburg, Gothenburg SE-405 30, Sweden *Corresponding author: nyandoro@udsm.ac.tz; samnyandoro@yahoo.com ABSTRACT Parasitic diseases including malaria, and other numerous microbial infections and physiological diseases are threatening the global population. Tanzanian coast shores are endowed with a variety of macroalgae (seaweeds), hitherto unsystematically explored to establish their biomedical potentials. Thus, antiplasmodial activity using malarial imaging assay, antimicrobial activity using microplate dilution technique, antioxidant activity using DPPH radical scavenging method and cytotoxicity using brine shrimp test were carried out on crude extracts from the selected species of algae (Acanthophora spicifera, Cystoseira myrica, Cystoseira trinodis, Laurencia filiformis, Padina boryana, Sargassum oligocystum, Turbinaria crateriformis, Ulva fasciata and Ulva reticulata) occurring along the coast of Tanzania. The extracts showed antimicrobial activities with MIC ranging from 0.3- 5.0 μg/mL against Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Cryptococcus neoformans; DPPH radical scavenging activity at EC 50 1.0- 100 μg/mL and cytotoxicity on brine shrimp larvae with LC 50 value ranging from20 - 1000 μg/mL. The extracts from C. myrica and P. boryana inhibited growth of Plasmodium falciparum (3D7 strain) by 80 and 71%, respectively at 40 μg/mL while a sesquiterpene debromolaurinterol (1) which was chromatographically isolated from C. myrica exhibited antiplasmodial activity with IC 50 20 μM whereas a sterol fucosterol (2) from P. boryana showed weak activity at 40 μM. Bioactivities portrayed by the investigated extracts indicate their ingredients as potential sources of bioactive agents that warrant further explorations. Keywords: Macrolgae, antiplasmodial, antimicrobial, antioxidant, cytotoxicity, DPPH radical scavenging, debromolaurinterol and fucosterol. INTRODUCTION Parasitic diseases such as malaria, numerous microbial infections and physiological diseases arising from cellular oxidation causing cancer, aging, heart diseases and several other chronic diseases are