Mimicking Halimane Synthases: Monitoring a Cascade of Cyclizations and Rearrangements from Epoxypolyprenes.

We have developed and rationalized a biomimetic transformation mimicking halimane synthases based on a Lewis acid-catalyzed cascade of cyclizations and rearrangements of epoxypolyprenes. Two rings, three stereogenic centers, and a new double bond were generated in a single chemical operation. Based on this cascade transformation, we achieved a unified strategy toward the stereoselective total syntheses of halimene-type terpenoids and analogues as a proof-of-concept study. This method has been applied to the rapid synthesis of diterpene isotuberculosinol, a virulence factor of Mycobacterium tuberculosis as a representative example.

Marine Microalgae with Anti-Cancer Properties.

Cancer is the leading cause of death globally and finding new therapeutic agents for cancer treatment remains a major challenge in the pursuit for a cure. This paper presents an overview on microalgae with anti-cancer activities. Microalgae are eukaryotic unicellular plants that contribute up to 40% of global primary productivity. They are excellent sources of pigments, lipids, carotenoids, omega-3 fatty acids, polysaccharides, vitamins and other fine chemicals, and there is an increasing demand for their use as nutraceuticals and food supplements. Some microalgae are also reported as having anti-cancer activity. In this review, we report the microalgal species that have shown anti-cancer properties, the cancer cell lines affected by algae and the concentrations of compounds/extracts tested to induce arrest of cell growth. We also report the mediums used for growing microalgae that showed anti-cancer activity and compare the bioactivity of these microalgae with marine anticancer drugs already on the market and in phase III clinical trials. Finally, we discuss why some microalgae can be promising sources of anti-cancer compounds for future development.

Xerophytic Lichens from Gypsiferous Outcrops of Arid Areas of Andalusia as a Source of Anti-Phytopathogenic Depsides.

In a survey to evaluate the potential of lichens associated with gypsum areas as sources of new antifungal metabolites, six species of lichens were collected in the gypsum outcrops of the Sorbas Desert (Diploschistes ocellatus and Seirophora lacunosa) and the Tabernas Desert (Cladonia foliacea, Acarospora placodiformis, Squamarina lentigera and Xanthoparmelia pokornyi) in southern Spain. Raw lichen acetone extracts were tested against a panel of seven phytopathogenic fungi, including Botrytis cinerea, Colletotrichum acutatum, Fusarium oxysporum f.sp cubense TR4, Fusarium ploriferaum, Magnaporthe grisea, Verticillium dahliae and Zymoseptoria tritici. Active extracts of Cladonia foliacea, Xanthoparmelia pokornyi and Squamarina lentigera were analyzed by HPLC-MS/MS and Molecular Networking to identify possible metabolites responsible for the antifungal activity. A total of ten depside-like metabolites were identified by MS/MS dereplication and NMR experiments, of which one was a new derivative of fumaroprotocetraric acid. The compounds without previously described biological activity were purified and tested against the panel of fungal phytopathogens. Herein, the antifungal activity against fungal phytopathogens of 4'-O-methylpaludosic acid, divaricatic acid and stenosporic acid is reported for the first time. Stenosporic and divaricatic acids displayed a broad antifungal spectrum against seven relevant fungal phytopathogens in a micromolar range, including the extremely resistant fungus F. oxysporum f. sp. cubense Tropical Race 4 (TR4). 4'-O-methylpaludosic acid exhibited specific antifungal activity against the wheat pathogen Z. tritici, with an IC50 of 38.87 µg/mL (87.1 µM) in the absorbance-based assay and 24.88 µg/mL (55.52 µM) in the fluorescence-based assay.