The dazzling marine zoantharians represent a reservoir of chemical diversity that remains to be unveiled. These fragile animals have so far been found to harbour the highly bioactive palytoxins or zoanthamines but also the harmless ecdysteroids or zoanthozanthins.

Two new zoanthamine alkaloids, namely 3-acetoxynorzoanthamine (1) and 3-acetoxyzoanthamine (2), have been isolated from the zoantharian Zoanthus cf. pulchellus collected off the coast of the Santa Elena Peninsula, Ecuador, together with three known derivatives: zoanthamine, norzoanthamine, and 3-hydroxynorzoanthamine. The chemical structures of 1 and 2 were determined by interpretation of their 1D and 2D NMR data and comparison with literature data. This is the first report of zoanthamine-type alkaloids from Zoanthus cf. pulchellus collected in the Tropical Eastern Pacific. The neuroinflammatory activity of all the isolated compounds was evaluated in microglia BV-2 cells and high inhibitory effects were observed in reactive oxygen species (ROS) and nitric oxide (NO) generation.

The first chemical study of the common species Terrazoanthus onoi, present off the coast of Ecuador, led to the identification of a new family of 2-aminoimidazole alkaloids named terrazoanthines A–C (1–3). Homologues 1 and 2 feature an unprecedented 6-(imidazol-5-yl)benzo[d]imidazole. Acyl substitution pattern and complete configurational assignments were deduced from comparison between experimental and theoretical ¹³C NMR and ECD data, respectively. These compounds may represent key derivatives in the biosynthesis of zoanthoxanthins.

The role that seaweeds play as primary producers and ecosystems engineers in marine coastal ecosystems is widely acknowledged. Seaweeds, however, are also important drivers in the development of the blue bioeconomy due to their vast diversity of unique chemicals with a broad range of industrial and biotechnological applications. In tropical regions, seaweed production has been focused on a few species only, because of their hydrocolloids used in the food industry. There is a strong need to identify new applications of red seaweed species in other sectors such as aquaculture. Therefore, to diversify the culture of red seaweeds, more tropical species need to be investigated for their chemical composition and potential application in aquaculture, and then, to develop a method for a sustainable cultivation of new seaweed candidates and enhance their economic potential. Based on this context, we analyze the potential value of the red edible seaweed Acanthophora spp., an under-valued seaweed species which is naturally abundant in tropical countries, and Kappaphycus spp., a commercially valuable seaweed commonly used for polysaccharide extraction. The vast chemical diversity of seaweeds (polysaccharides, phytohormones, amino acids, and pigments) has led to research on a wide range of applications in aquaculture, including pathogen control, immunostimulant, antioxidant, bioremediation, feed, UV protectants, increase in seafood shelf life, animal colorant, and growth regulator for microalga culture. This review hopes to stimulate the interest among seaweed researchers to investigate other local seaweed species and seek greater added value of their biomass and chemical compounds and their applications in the aquaculture sector. Additionally, this information will help stakeholders to benefit from these two red seaweeds by contributing to the diversification of the blue bioeconomy in tropical countries.

Zoantharians represent a group of marine invertebrates widely distributed from shallow waters to the deep sea. Despite a high diversity and abundance in the rocky reefs of the Pacific Ocean, very few studies have been reported on the diversity of this group in the Tropical Eastern Pacific coasts. While molecular techniques recently clarified some taxonomic relationships within the order, the taxonomy of zoantharians is still highly challenging due to a lack of clear morphological characters and confusing use of different data in previous studies. Our first insight into the zoantharian diversity at El Pelado Marine Protected Area - Ecuador led to the identification of six species:Terrazoanthus patagonichus;Terrazoanthussp.;Antipathozoanthus hickmani;Parazoanthus darwini;Zoanthuscf.pulchellus; andZoanthuscf.sociatus. A metabolomic approach using UHPLC-HRMS was proven to be very efficient as a complementary tool in the systematics of these species and specialized metabolites of the ecdysteroid and alkaloid families were identified as key biomarkers for interspecific discrimination. These results show good promise for an application of this integrative approach to other zoantharians.

Despite a large occurrence, especially over the Pacific Ocean, the chemical diversity of marine invertebrates belonging to the order Zoantharia is largely underexplored. For the two species of the genus Antipathozoanthus no chemical study has been reported so far. The first chemical investigation of Antipathozoanthus hickmani collected at the Marine Protected Area “El Pelado”, Santa Elena, Ecuador, led to the isolation of four new ecdysteroid derivatives named ecdysonelactones. The structures of ecdysonelactones A–D (1–4) were determined based on their spectroscopy data, including 1D and 2D NMR and HRMS. The four compounds of this family of ecdysteroids feature an unprecedented γ-lactone fused at the C-2/C-3 position of ring A. These derivatives exhibited neither antimicrobial nor cytotoxic activities.