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The economic and environmental viability of dedicated terrestrial energy crops is in doubt. The production of large scale biomass (macroalgae) for biofuels in the marine environment was first tested in the late 1960’s. The culture attempts failed due to the engineering challenges of farming offshore. However the energy conversion via anaerobic digestion was successful as the biochemical composition of macroalgae makes it an ideal feedstock. The technology for the mass production of macroalgae has developed principally in China and Asia over the last 50 years to such a degree that it is now the single largest product of aquaculture. There has also been significant technology transfer and macroalgal cultivation is now well tried and tested in Europe and America. The inherent advantage of production of biofuel feedstock in the marine environment is that it does not compete with food production for land or fresh water. Here we revisit the idea of the large scale cultivation of macroalgae at sea for subsequent anaerobic digestion to produce biogas as a source of renewable energy, using a European case study as an example.

‘Biogas’ is the word used to denote the mixtures of methane and carbon dioxide produced by bacterial action, in vitro, on various organic substrates. In vitro’, because similar mixtures of methane and carbon dioxide are formed by essentially the same bacterial actions in the gut of animals (in particular the rumen and similar organs of the herbivore gut; see previous papers) and in decaying vegetation in marshes and river beds.

Although Lobophora belongs to a marine algal family (Dictyotaceae) that produces a large array of secondary metabolites, it has received little atten- tion compared to other genera, such as Dictyota, in terms of natural compounds isolation and character- ization. However, metabolites produced by Lobo- phora species have been found to exhibit a wide array of bioactivities including pharmacological (e.g. antibacterial, antiviral, antioxidant, antitumoral), pes- ticidal, and ecological. This review aims to report the state-of-the-art of the natural products isolated from Lobophora species (Dictyotales, Phaeophyceae) and their associated bioactivities. All bioactivities docu- mented in the literature are reported, therefore including studies for which pure active substances were described, as well as studies limited to extracts or fractions. From the early 1980s until today, 49 scientific works have been published on Lobophora chemistry and bioactivity, among which 40 have reported bioactivities. Only six studies, however, have identified, characterized and tested no less than 23 bioactive pure compounds (three C21 polyunsaturated alcohols, three fatty-acids, a macrolactone, 11 polyke- tides, a few sulfated polysaccharides, three sulfolipids, a tocopherol derivative). The present review intends to raise awareness of chemists and biologists given the recent significant taxonomic progress of this brown algal genus, which holds a promising plethora of natural products yet to be discovered with ecological and pharmacological properties.