Antifungal Potential of Marine Organisms of the Yucatan Peninsula (Mexico) against Medically Important Candida spp.

Invasive fungal infections represent a global health threat. They are associated with high mortality and morbidity rates, partly due to the ineffectiveness of the available antifungal agents. The rampant increase in infections recalcitrant to the current antifungals has worsened this scenario and made the discovery of new and more effective antifungals a pressing health issue. In this study, 65 extracts from marine organisms of the Yucatan Peninsula, Mexico, were screened for antifungal activity against Candida albicans and Candida glabrata, two of the most prevalent fungal species that cause nosocomial invasive fungal infections worldwide. A total of 51 sponges, 13 ascidians and 1 gorgonian were collected from the coral reef and mangrove forest in the Yucatan Peninsula (Mexico) and extracted with organic solvents. Nine crude extracts showed potent antifungal activity, of which four extracts from the sponge species Aiolochroia crassa, Amphimedon compressa, Monanchora arbuscula and Agelas citrina had promising activity against Candida spp. Bioassay-guided fractionation of the M. arbuscula extract revealed the remarkable fungicidal activity of some fractions. Analysis of the chemical composition of one of the most active fractions by UHPLC-HRMS and NMR indicated the presence of mirabilin B and penaresidin B, and their contribution to the observed antifungal activity is discussed. Overall, this work highlights marine organisms of the Yucatan Peninsula as important reservoirs of natural products with promising fungicidal activity, which may greatly advance the treatment of invasive fungal infections, especially those afflicting immunosuppressed patients.

Antimicrobial Diterpene Alkaloids from an Agelas citrina Sponge Collected in the Yucatán Peninsula.

Three new diterpene alkaloids, (+)-8-epiagelasine T (1), (+)-10-epiagelasine B (2), and (+)-12-hydroxyagelasidine C (3), along with three known compounds, (+)-ent-agelasine F (4), (+)-agelasine B (5), and (+)-agelasidine C (6), were isolated from the sponge Agelas citrina, collected on the coasts of the Yucatán Peninsula (Mexico). Their chemical structures were elucidated by 1D and 2D NMR spectroscopy, HRESIMS techniques, and a comparison with literature data. Although the synthesis of (+)-ent-agelasine F (4) has been previously reported, this is the first time that it was isolated as a natural product. The evaluation of the antimicrobial activity against the Gram-positive pathogens Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis showed that all of them were active, with (+)-10-epiagelasine B (2) being the most active compound with an MIC in the range of 1-8 µg/mL. On the other hand, the Gram-negative pathogenes Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae were also evaluated, and only (+)-agelasine B (5) showed a moderate antibacterial activity with a MIC value of 16 µg/mL.

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

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.

Octopus maya parasites off the Yucatán Peninsula, Mexico. I. Faunal assemblages.

The red octopus Octopus maya Voss et Solís-Ramírez, 1966 is an endemic species found exclusively off the coast of the Yucatán Peninsula, Mexico; its fishery is one of the most important along the Atlantic coast of Mexico and the Caribbean Sea. To date, the parasite fauna of Octopus spp. in southern Mexico remains unknown. In this study, we present the parasite fauna of O. maya from 8 localities along the Yucatán Peninsula. From August 2009 to June 2010, a total of 1202 specimens of O. maya were caught by artisanal fisheries and examined. Twenty parasite taxa were recorded from all octopus examined: 7 cestodes, 8 digeneans, 3 nematodes, 1 copepod and 1 coccidian. All taxa are new records for this host species, and the sampled locations represent new records of the geographic distribution of these parasite taxa. The gills and the intestine were the micro-habitats in which the highest number of taxa were found. More than half of the parasites (13 taxa) that we found infected O. maya via its feeding habits, although a high number of taxa (n = 9) colonized via active transmission. Cestoda and Digenea were the taxonomic groups with the highest number of taxa. Prochristianella sp. showed the highest prevalence and mean abundance values in the localities where it was present. This work represents the first study on the parasite fauna of any cephalopod species in Mexico.

Metazoan parasite infracommunities of Mycteroperca bonaci (Poey, 1960) (Pisces: Epinephelidae) in reef and coastal environments off the coast of Yucatán, México.

The black grouper Mycteroperca bonaci is a commercially important fish off the coast of Yucatan, Mexico. To investigate possible differences between parasite communities in two different environments, 60 fish were collected from two areas during 2010 and 2011 and examined for parasites. The fish were classified into two age groups, in each of which the parameters of parasitic infection - prevalence, abundance and intensity - were determined. Parasite faunas were further described at the infracommunity level. Using both univariate (PERMANOVA) and multivariate statistical methods, the values of richness, abundance, diversity and Brillouin evenness as well as the Index values of Bray-Curtis and Jaccard for similarity were calculated and compared. The results of these tests and of CAP discriminant analyses at the two sites showed the existence of two distinct parasite communities. The parasite taxa mainly responsible for the differences were the digeneans Dollfustrema sp., Prosorhynchus spp., Lepidapedoides epinepheli and Hamacreadium mutabile, and the nematode Philometra salgadoi. The potential for some of these parasites to be used as biological tags for stock identification of M. bonaci is discussed.

Parapharyngodon n. spp. (Nematoda: Pharyngodonidae) parasites of hylid frogs from Mexico and review of species included in the genus.

Two new species of Parapharyngodon Chatterji, 1933 , parasitizing 3 species of hylid frogs (Diaglena spatulata, Triprion petasatus, and Trachycephalus typhonius) from Mexico are described. The 2 new species share the presence of a gubernaculum with Parapharyngodon lamothei and belong to the group of those species with short spicule; both differ from the remaining species of the genus in the papillar pattern on ventrolateral and dorsal lips and in the thickness of cuticular annulations and cuticular ornamentation in the female specimens. These are the third and fourth reports of Parapharyngodon spp. parasitizing hylid frogs. In addition to the egg characteristics, we propose that length of the lateral alae is also a taxonomically relevant feature to differentiate species of the genus. A bibliographic review of all species historically assigned to Parapharyngodon is given, including those that have been declared species inquirenda, or transferred to other genera and those that are considered valid.

High serotonin levels due to the presence of the acanthocephalan Hexaglandula corynosoma could promote changes in behavior of the fiddler crab Uca spinicarpa.

Between February and June 2010, 113 fiddler crabs Uca spinicarpa were collected from the Chuburna lagoon system on the northern coast of the Yucatan Peninsula, México. Of the 68 crabs gathered outside their burrows, 13 were infected with 25 cystacanths of Hexaglandula corynosoma (intensity of infection from 1 to 5) and the remaining 55 crabs were uninfected. The other 45 crabs were found inside their burrows and only one was found infected with 1 cystacanth of H. corynosoma. Serotonin (5-HT) levels were higher in the group of crabs infected with H. corynosoma in contrast to the group of uninfected crabs and the group of those infected with other parasites. A redundancy analysis corroborated a positive relationship between 5-HT and the intensity of infection with H. corynosoma. In contrast, dopamine levels remained similar among different groups of crabs.

A new cucullanid from the black grouper Mycteroperca bonaci (Osteichthyes: Serranidae) off the coast of Yucatán, México.

Cucullanus mycteropercae n. sp. is described from the intestine of the black grouper, Mycteroperca bonaci Poey, from the northern coast of Yucatán, México. The new species is readily distinguishable from other Cucullanus species because it possesses an ellipsoidal papilla-like structure situated medially on the anterior cloacal lip of males. Other differentiating characters include the variable position of postcloacal pair 8 in males, the subventral position of phasmids, a slightly ventrally hooked posterior end of gubernaculum, and the presence of a large, cylindroconical sclerotized tail end in both sexes. This is the fourth record of a marine cucullanid off the Yucatán Peninsula in México belonging to Cucullanus Müller, 1777.

Helminth parasites in Chaunus marinus and Cranopis valliceps (Anura: Bufonidae) from Lagunas Yalahau, Yucatan, Mexico.

Eight helminth taxa were found parasitizing Chaunus marinus (n = 40) and Cranopsis valliceps (n = 40) from the Parque Estatal Lagunas Yalahau, Yucatan, Mexico. Seven taxa (2 digeneans: Langeronia macrocirra, Mesocoelium monas; 1 acanthocephalan: Oncicola sp.; 3 nematodes: Rhabdias füleborni, Aplectana itzocanensis, Cruzia morleyi; and a nematode larva) were found in C. marinus, while 4 taxa (all nematodes: Rhabdias fuelleborni, Aplectana itzocanensis, Ozwaldocruzia sp., and a nematode larva) were present in C. valliceps. Nematodes, particularly A. iztocanensis, showed high prevalence, mean abundance, and mean intensity values for both species of amphibians. The occurrence of R. fuelleborni, M. monas, L. macrocirra, and C. morleyi in these amphibians from the Yucatan Peninsula confirms their neotropical distribution, while the presence of A. itzocanensis increases its geographical distribution, suggesting a preference by neotropical, rather than neartic areas.

A new species of Oochoristica (Eucestoda: Cyclophyllidea) parasite of Ctenosaura oaxacana (Reptilia: Iguanidae) from Mexico.

Oochoristica whitfieldi n. sp., parasitizing the intestine of the Oaxacan black iguana Ctenosaura oaxacana (Kohler and Hasbun, 2001), in Ruinas de Guiengola, Oaxaca state, Mexico, is described. The new species can be distinguished from all 4 congenera infecting Iguanidae in the neotropical realm in possessing a lower mean number of testes (122 in O. acapulcoensis Brooks, Pérez-Ponce de León, and García-Prieto, 1999; 62 in O. guanacastensis Brooks, Pérez-Ponce de León, and García-Prieto, 1999, and 95 in O. leonregagnonae Arizmendi-Espinosa, García-Prieto, and Guillén-Hernández, 2005, vs. 35 in O. whitfieldi), and a wider scolex (0.450-0.600, 0.475-0.537, 0.5-0.8, vs. 0.25-0.26, respectively). Oochoristica iguanae Bursey and Goldberg, 1996 differs from the new Mexican species in having a longer strobila (60-110 mm vs. 14.4-33.7 mm, respectively), fewer ovarian sublobes (6 vs. 11-17), and a cirrus pouch that hardly reaches excretory canals (whereas in O. whitfieldi the cirrus pouch widely overpasses these canals).

Intraspecific variation of Haematoloechus floedae Harwood, 1932 (Digenea: Plagiorchiidae), from Rana spp. in North and Central America.

Haematoloechus floedae was originally described from the lungs of Rana catesbeiana in Texas, and later reported in Florida, in the United States. It was proposed to be synonymous with H. breviplexus, H. parviplexus, and H. varioplexus. We obtained specimens of H. floedae from Rana brownorum and R. vaillanti in Yucatán, Mexico; R. cf. forreri and R. taylori in Guanacaste, Costa Rica; and R. catesbeiana in Georgia and California. Some specimens were processed for morphological study; sequences of the 28S of the rDNA and the mitochondrial COI were obtained from several specimens of each population. Phylogenetic analysis of molecular data indicates studied populations constitute a single taxon, different from H. varioplexus, H. breviplexus, and H. parviplexus. Some morphological characters remain constant among populations of H. floedae, and are useful for differentiating this species. These include the oral sucker-pharynx ratio, oral sucker-ventral sucker ratio, ovary and testes shape, extension of uterine longitudinal loops, and extension of vitelline follicles (in fully developed worms). Sequence homogeneity among populations of H. floedae suggests a recent spread, perhaps due to the introduction of R. catesbeiana for culture to the western United States, southeast Mexico, and Costa Rica.

Dichelyne (Dichelyne) bonacii n. sp. (Nematoda: Cucullanidae) from the grey snapper Lutjanus griseus and the black grouper Mycteroperca bonaci off the coast of Yucatán, Mexico.

A new cucullanid, Dichelyne bonacii n. sp., is described from the intestine of the grey snapper Lutjanus griseus and the stomach of the black grouper Mycteroperca bonaci off the coast of Yucatán. The absence of a ventral precloacal sucker and the presence of 11 pairs of caudal papillae in males allocate it to the subgenus Dichelyne. It differs from its congeners in body dimensions and by having two almost equal spicules (left 712-950 and right 722-945microm), two intestinal caeca and in the position of the deirids and excretory pore. Apparently, L. griseus acts as definitive host of this species, whereas M. bonaci may be considered as a postcyclic host. This new species represents the first record of a nematode of the subgenus Dichelyne in marine fishes of Mexico.