The genus Amphidinium Clap. & J. Lachm. comprises a high diversity of planktonic and benthic (epiphytic and sand-dwelling) dinoflagellates from marine and freshwater ecosystems. High morphological plasticity and vaguely defined genus characteristics (e.g., a small epicone size) have complicated the clear delineation of species boundaries. Although six Amphidinium morphospecies have been reported from Mexican coastal waters, species identifications are uncertain and not generally supported by molecular phylogenetic data. In this study, seven isolates of Amphidinium from diverse benthic coastal locations on the NE Pacific, Gulf of California, and southern Gulf of Mexico were subjected to critical morphological analysis using photonic and scanning electron microscopy. The phylogenetic reconstruction was based on nuclear-encoded, partial large-subunit (LSU) rDNA and internal transcribed spacer I and II (ITS1 and ITS2) sequences. The revised phylogenetic analysis was consistent with the traditional subdivision of the genus Amphidinium into two sister groups: Herdmanii and Operculatum clades. This study provided the first confirmed records of A. theodorei and A. massartii from coastal waters of Mexico. The molecular phylogenetic evidence indicated that the morphologically described A. cf. carterae from Baja California was in fact more closely allied with A. eilatiensis sequences. A few Amphidinium species are known to form toxigenic (i.e., fish-killing) harmful algal blooms worldwide, and therefore knowledge on species diversity and biogeography is critical in developing effective strategies for evaluating the potential emerging threat in Mexican coastal waters.

Among aquatic organisms, marine dinoflagellates are essential sources of bioactive metabolites. The benthic dinoflagellate Coolia malayensis produces metabolites that have exhibited substantial and specific cytotoxicity on cancer cells; however, isolation and identification of the purified compounds remain a challenge. This study reports C. malayensis biomass multi-step extraction plus chemical analyses for identifying compounds with antineoplastic activity. Through bio-directed fractionation, the cytotoxicity of extracts and fractions was tested on H1299 (lung), PC-3 (prostate), HeLa (cervical), and MCF-7 (breast) cancer cell lines. Dichloromethane (DCM) phase, hydroalcoholic (HYD) secondary extract, and methanolic (MET) extract showed cytotoxic effects on all cell lines. Active extracts and fractions were analyzed by HPLC-QTOF-MS, ¹H, and ¹³C NMR. Cell lines H1299 and PC-3 treated with fractions F4, F7, and DCM2-AQ-Ch sub-extract showed morphological changes resembling those observed in the apoptosis control, and no signs of necrosis were observed. The selectivity of fraction F7 was above 100 μg mL⁻¹ for healthy cells, while cytotoxic activity was observed in cancer cells. This fraction was identified as mostly fatty acids (FA) by NMR. Seventeen compounds with reported biological activities, such as antioxidant, analgesic, antiviral, and anticancer, were identified from C. malayensis extracts and fractions. Among them, the phycotoxins gambieric acid A and B, okadaic acid, and dinophysistoxin-1 were detected. Further studies are needed to reveal more significant anti-cancer potential from C. malayensis.

Members of the benthic marine dinoflagellate genus Amphidinium produce a variety of bioactive compounds, exhibiting potent cytotoxicity in cell assays. Crude methanolic extracts from three genetically distinct cultured strains of A. eilatiense J.J. Lee were screened for cytotoxicity against three human breast and four lung cancer cell lines to evaluate potential applications in anticancer therapy. A standard tetrazolium cell viability assay demonstrated that the methanolic crude extract (100 µg mL⁻¹) from strain AeSQ181 reduced cell viability by 20–35% in five cancer cell lines. Further bioassay-guided fractionation of these crude extracts yielded non-polar fractions (FNP-5 and FNP-6) with particularly high cytotoxic activity against lung (H1563) and breast (MDA-MB-231) adenocarcinoma cell lines. Untargeted metabolomic analysis of cytotoxic fractions by liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) revealed a much richer chemical diversity profile than previous toxigenicity studies on Amphidinium that exclusively focused on linear and cyclic polyethers and their macrolide analogs as putative cytotoxins. This untargeted metabolomic study showed substantial differences in chemical composition between the biologically active and non-active fractions. Preliminary biological and chemical characterization of these A. eilatiense fractions confirms that this species is a rich source of bioactive natural products with potential applications such as anticancer therapeutics.

This review outlines a critical segment of the integration process involved in the discovery of compounds with biological activity as well as pharmacological and biotechnological potential, specifically those derived from dinoflagellates. It discusses the challenges and opportunities in exploring these bioactive molecules in pharmacological research. The objective is to detail some key cell culture techniques, which involve the precise control of experimental conditions and the monitoring of cellular response parameters —including viability, proliferation, cytotoxicity, and cell death— and the appropriate selection of cancerous and non-cancerous human cell lines. Furthermore, this review explores the impact of the various limitations associated with the large-scale biomass production required to obtain pure compounds. The integration of these approaches through specific in vitro assays enables the biological characterization of bioactive compounds or active fractions, underscoring the essential role of cell culture as a strategic tool in the search for novel anticancer agents from marine dinoflagellates.