Five new diterpenes derivatives named as ornatin A, B, C, D and E, in addition to six known related diterpenes were isolated from the aerial parts of cultivated specimens of Plectranthus ornatus. The structures were elucidated using a combination of 1D/2D nuclear magnetic resonance (NMR) spectroscopy, high-resolution electrospray ionization mass spectrometry (HRESIMS) and comparison with published NMR data of analogous compounds. All isolated compounds were assayed against four human cancer cell lines, and Gram-positive and Gram-negative bacteria strains. None of them showed any cytotoxic activity, but ornatin C, D, E and three related diterpenes displayed marginal bactericidal or bacteriostatic effects against the Gram-positive strains.

Abstract Dinoflagellates are an important source of unique bioactive secondary metabolites. Symbiotic species, commonly named zooxanthellae, transfer most of their photosynthetically fixed carbon to their host. The mutualistic relationship provides the organic metabolites used for energy production but there are very few reports of the role of the dinoflagellates in the production of secondary metabolites in the symbiotic association. Corals and other related cnidarians are the most well-known animals containing symbiotic dinoflagellates. In the present paper we describe the isolation of amphidinolide P (1) from the octocoral Stragulum bicolor and its prey, the nudibranch Marionia limceana, collected off the coasts of Fortaleza (Ceará, Brazil). The coral extracts also contained 3-O-methyl derivative (2) of amphidinolide P, together with minor compounds still under investigation. Amphidinolides have been so far reported only in laboratory cultures of Amphidinium sp., thus compounds 1 and 2 represents the first identification of these polyketides in invertebrates. The finding proves the possibility to isolate amphidinolides from a natural symbiosis, enabling further biological and biotechnological studies.

Previous studies demonstrated that the crude extract of the ascidian Eudistoma vannamei, endemic from northeasttern Brazil, strongly hinders growth of tumor cells in vitro by inducing apoptosis due to tryptophan derivatives, which are commonly found in bacteria. This study presents a bioactivity-guided screening among actinomycetes, associated with E. vannamei, aiming at recognizing active principles with biological relevance. Twenty strains of actinomycetes, designated as EVA 0101 through 0120, were isolated from colonies of E. vannamei among which 11 were selected for cytotoxicity evaluation. The extracts from EVA 0102, 0103, 0106, 0109 and 0113 were the most active, and were further studied for IC50 determination and chemical analysis by ¹H NMR. IC50 values obtained ranged from 3.62 µg mL-1 (for EVA 0109 in leukemia cells) to 84.65 µg/mL (for EVA 0106 in melanoma cells). All active extracts exhibited the same TLC and spectroscopic profiles, suggesting the presence of quinones and other related secondary metabolites. Furthermore, these strains were identified and compared based on their respective 16S rRNA sequences. The results herein identified the five strains as Micromonospora spp. while phylogenetic analysis suggests that they are possibly two different Micromonospora species producing the cytotoxic compounds.

Estudios previos demostraron que el extracto crudo de la ascidia Eudistoma vannamei, endémica de la costa noreste de Brasil, obstaculiza fuertemente el crecimiento de células tumorales in vitro por inducir apoptosis. El análisis químico del extracto sugirió la presencia de derivados de triptófano, comúnmente encontrados en bacterias. El estudio presenta un screening de citotoxicidad en actinomicetos asociados con E. vannamei, para reconocer principios activos biológicamente relevantes. Veinte cepas de actinomicetos, designados como EVA 0101 hasta 0120, fueron aisladas de colonias de E. vannamei y 11 fueron seleccionadas para la evaluación de citotoxicidad. Los extractos de EVA 0102, 0103, 0106, 0109 y 0113 resultaron las más activas y fueron estudiadas para determinación de la CL50 y perfiles de CCF y ¹H RMN. Las CL50 obtenidas oscilaron entre 3,62 (EVA 0109 en las células de leucemia) y 84,65 µg mL-1 (EVA 0106 en las células de melanoma). Los extractos activos presentan el mismo perfil de CCF y espectroscópico, lo que sugiere la presencia de quinonas y metabolitos secundarios relacionados. Además, las cinco cepas fueron identificadas y comparadas sobre la base de sus secuencias de 16S ARNr. Las que se identificaron como Micromonospora spp. y el análisis filogenético sugiere que sean por lo menos dos especies de Micromonospora las que producen los compuestos citotóxicos.