ORIGINAL PAPER Asparagopsis armata and Sphaerococcus coronopifolius as a natural source of antimicrobial compounds Susete Pinteus • Celso Alves • Hugo Monteiro • Ernesto Arau ´jo • Andre ´ Horta • Rui Pedrosa Received: 4 September 2014 / Accepted: 2 January 2015 Ó Springer Science+Business Media Dordrecht 2015 Abstract Methanol, n-hexane and dichloromethane extracts of twelve marine macro-algae (Rhodophyta, Chlo- rophyta and Heterokontophyta divisions) from Peniche coast (Portugal) were evaluated for their antibacterial and anti- fungal activity. The antibacterial activity was evaluated by disc diffusion method against Bacillus subtilis (gram posi- tive bacteria) and Escherichia coli (gram negative bacteria). Saccharomyces cerevisiae was used as a model for the antifungal activity by evaluating the growth inhibitory activity of the extracts. The high antibacterial activity was obtained by the Asparagopsis armata methanolic extract (10 mm–0.1 mg/disc), followed by the Sphaerococcus cor- onopifolius n-hexane extract (8 mm–0.1 mg/disc), and the Asparagopsis armata dichloromethane extract (12 mm– 0.3 mg/disc) against Bacillus subtilis. There were no posi- tive results against Escherichia coli. Sphaerococcus coron- opifolius revealed high antifungal potential for n-hexane (IC 50 = 40.2 lg/ml), dichloromethane (IC 50 = 78.9 lg/ ml) and methanolic (IC 50 = 55.18 lg/ml) extracts against Saccharomyces cerevisiae growth. The antifungal potency of the Sphaerococcus coronopifolius extracts was similar with the standard amphotericin B. Asparagopsis armata and Sphaerococcus coronopifolius reveal to be interesting sources of natural compounds with antimicrobial properties. Keywords Marine algae Á Antibacterial activity Á Antifungal activity Á Seaweeds Á Marine natural compounds Á Natural antibiotics Introduction Natural compounds have been applied for the treatment of many diseases since ancient time all over the world. Resistance of the microorganisms to the commonly used antibiotic has enhanced morbidity and mortality and has triggered the search for new drugs. As a consequence of an increasing demand for biodiversity in the screening pro- gram seeking therapeutic drugs from natural products, there is greater interest particularly in the oceans throughout the world (Murray et al. 2013). Several marine organisms produce bioactive metabolites in response to ecological pressures such as competition for space, prevention of predation and the ability to success- fully reproduce (Ko ¨nig et al. 1994; Bhakuni and Rawat 2005; Salvador et al. 2007). The exploration of this chemical diversity for pharmaceutical purposes has revealed important chemical prototypes for the discovery of new agents. Focusing on bioproducts, recent trends in drug research from natural sources suggest that algae are one of the major producers of bioactive secondary metab- olites with high biomedical potential that have the ability to interfere with the pathogenesis of many human diseases. A variety of biological activities for these compounds have been reported including antibacterial, antifungal, antitu- mor, anticoagulant and antiviral (Mayer et al. 2007; Mur- ray et al. 2013). Moreover, algae have the potential to provide not only novel biologically active substances, but also essential compounds for human nutrition (Pinte ´us et al. 2009; Go ´mez-Ordo ´n ˜ez et al. 2010). S. Pinteus Á C. Alves Á H. Monteiro Á E. Arau ´jo Á A. Horta Á R. Pedrosa (&) Marine Resources Research Group (GIRM), ESTM, Polytechnic Institute of Leiria, 2520-641 Peniche, Portugal e-mail: rpedrosa@ipleiria.pt R. Pedrosa Centre of Pharmacology and Chemical Biopathology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal 123 World J Microbiol Biotechnol DOI 10.1007/s11274-015-1797-2