Marine Organisms from the Yucatan Peninsula (Mexico) as a Potential Natural Source of Antibacterial Compounds

[Abstract] A total of 51 sponges (Porifera) and 13 ascidians (Chordata) were collected on the coast of the Yucatan Peninsula (Mexico) and extracted with organic solvents. The resulting extracts were screened for antibacterial activity against four multidrug-resistant (MDR) bacterial pathogens: the Gram-negative Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa and the Gram-positive Staphylococcus aureus. The minimum inhibitory concentrations (MICs) of the organic extracts of each marine organism were determined using a broth microdilution assay. Extracts of eight of the species, in particular the Agelas citrina and Haliclona (Rhizoniera) curacaoensis, displayed activity against some of the pathogens tested. Some of the extracts showed similar MIC values to known antibiotics such as penicillins and aminoglycosides. This study is the first to carry out antimicrobial screening of extracts of marine sponges and ascidians collected from the Yucatan Peninsula. Bioassay-guided fractionation of the active extracts from the sponges Amphimedon compressa and A. citrina displayed, as a preliminary result, that an inseparable mixture of halitoxins and amphitoxins and (-)-agelasine B, respectively, are the major compounds responsible for their corresponding antibacterial activities. This is the first report of the antimicrobial activity of halitoxins and amphitoxins against major multidrug-resistant human pathogens. The promising antibacterial activities detected in this study indicate the coast of Yucatan Peninsula as a potential source of a great variety of marine organisms worthy of further research.This work was supported by Grants RTI2018-093634-B-C22 (AEI/FEDER, EU) from the State Agency for Research (AEI) of Spain, co-funded by the FEDER Programme from the European Union, by projects PI15/00860 and PI18/00501 to GB and PI14/00059 and PI17/01482 to AB (Instituto de Salud Carlos III) and BLUEBIOLAB (0474_BLUEBIOLAB_1_E), Programme INTERREG V A of Spain-Portugal (POCTEP). The study was also funded by projects IN607A 2016/22 (GAIN- Agencia Gallega de Innovación - Consellería de Economía, Emprego e Industria) and GRC2018/039 and Agrupación Estratégica CICA-INIBIC ED431E 2018/03 (Consellería de Educación, Universidades e Formación Profesional) from the Xunta de Galicia (autonomous government of the region). Support was also provided by Planes Nacionales de I+D+i 2013-2016 and ISCIII, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD16/0016/006) co-financed by European Development Regional Fund "A way to achieve Europe" and the operative program Intelligent Growth 2014-2020. J.C.V.U. was financially supported by the pFIS Programme (FI18/00315), M.M.G. was financially supported by a Clara Roy grant (SEIMC) and C.L.M. by IN606A-2019/029. D.P.P. received a fellowship from the program National Council of Science and Technology (CONACYT) of Mexico and the Secretariat of Research, Innovation and Higher Education (SIIES) of Yucatan (Mexico)Xunta de Galicia; IN607A 2016/22Xunta de Galicia; GRC2018/039Xunta de Galicia; ED431E 2018/03Xunta de Galicia; IN606A-2019/02