Marine environment has demonstrated to be an interesting source of compounds with uncommon and unique chemical features on which the molecular modeling and chemical synthesis of new drugs can be based with greater efficacy and specificity for the therapeutics. Cancer is a growing public health threat, and despite the advances in biomedical research and technology, there is an urgent need for the development of new anticancer drugs. In this field, it is estimated that more than 60% of commercially available anticancer drugs are natural biomimetic inspired. Among the marine organisms, algae have revealed to be one of the major sources of new compounds of marine origin, including those exhibiting antitumor and cytotoxic potential. These compounds demonstrated ability to mediate specific inhibitory activities on a number of key cellular processes, including apoptosis pathways, angiogenesis, migration and invasion, in both in vitro and in vivo models, revealing their potential to be used as anticancer drugs. This review will focus on the bioactive molecules from algae with antitumor potential, from their origin to their potential uses, with special emphasis to the alga Sphaerococcus coronopifolius as a producer of cytotoxic compounds.

Seaweeds, i.e. macroalgae that occupy the littoral zone, are a great source of compounds with diverse applications; their types and content greatly determine the potential applications and commercial values. Algal polysaccharides, namely the hydrocolloids: agar, alginate and carrageenan, as well as other non-jellifying polysaccharides and oligosaccharides, are valuable bioproducts. Likewise, pigments, proteins, amino acids and phenolic compounds are also important, exploitable compounds. For the longest time the dominant market for macroalgae has been the food industry. More recently, several other industries have increased their interest in algal-derived products, e.g. cosmetics, pharmaceuticals and more recently, as a source of feedstock for biorefinery applications. This manuscript reviews the chemical composition of dominant macroalgae, as well as their potential added-value products and applications. Particular attention is devoted to the macroalgal species from the Iberian Peninsula. This is located in the Southwest of Europe and is influenced by the distinct climates of the Mediterranean Sea and the Atlantic Ocean, representing a rich spot of marine floral biodiversity.

Cancer and infectious diseases continue to be a major public health problem, and new drugs are necessary. As marine organisms are well known to provide a wide range of original compounds, the aim of this study was to investigate the bioactivity of the main constituents of the cosmopolitan red alga, Sphaerococcus coronopifolius. The structure of several bromoditerpenes was determined by extensive spectroscopic analysis and comparison with literature data. Five molecules were isolated and characterized which include a new brominated diterpene belonging to the rare dactylomelane family and named sphaerodactylomelol (1), along with four already known sphaerane bromoditerpenes (2–5). Antitumor activity was assessed by cytotoxicity and anti-proliferative assays on an in vitro model of human hepatocellular carcinoma (HepG-2 cells). Antimicrobial activity was evaluated against four pathogenic microorganisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. Compound 4 exhibited the highest antimicrobial activity against S. aureus (IC₅₀ 6.35 µM) and compound 5 the highest anti-proliferative activity on HepG-2 cells (IC₅₀ 42.9 µM). The new diterpene, sphaerodactylomelol (1), induced inhibition of cell proliferation (IC₅₀ 280 µM) and cytotoxicity (IC₅₀ 720 µM) on HepG-2 cells and showed antimicrobial activity against S. aureus (IC₅₀ 96.3 µM).