Reassignment of crispatene, isolation and chemical characterization of stachydrine, isolated from the marine mollusk Elysia crispata.

The molluscan genus Elysia Risso, 1818 (Sacoglossa) is composed of shell-less herbivore sea slugs. From these marine organisms, polyketides such as polypropynates have been isolated and showed cytotoxic, antibiotic, and antifungal, and antiviral properties. In this work, we reported the isolation, and structure elucidation of two compounds isolated from marine mollusk E. crispata. Both compounds isolated, crispatene (1) and stachydrine (2), were purified by HPLC. The chemical structure of compound (1) was reassigned through 1D and 2D NMR experiments and high-resolution electrospray ionization mass spectrometry (HRESIMS). On the other hand, this is the first time that compound (2) has been found in this species of mollusk or the marine environment, previously, (2) has only been found in terrestrial plants or bacteria in symbiosis with plants.

Synthesis and biological evaluation of ( - )-13,14-dihydroxy-8,11,13-podocarpatrien-7-one and derivatives from (+)-manool.

13,14-Dihydroxy-8,11,13-podocarpatrien-7-one (1) and a series of ring C aromatic diterpene derivatives were synthesised from (+)-manool (4) and evaluated for their cytotoxic, leishmanicidal and trypanocidal activities. Our results indicated that compound 1 and other podocarpane-type intermediates are cytotoxic. Cleavage of C6-C7 bond of compound 7 improved cytotoxic activity, indicating that, in particular, the 6,7-seco-podocarpane-type compound 20 might serve as a lead compound for further development.

Facile access to optically active ring C aromatic diterpene derivatives from (+)-manool. first synthesis of 13,14-dihydroxy8,11,13-podocarpatrien-7-one.

14,15,17-Trinorlabdan-8,13-dione 6 was efficiently synthesized via ozonolysis of(+)-manool (4) followed by treatment with aqueous NaOH in the presence of tetra-n-butylammonium bromide as catalyst. This protocol has the advantages of high yield, mild conditions and simple procedure. Utilizing this strategy, the first enantiospecific synthesis of 13,14-dihydroxy-8,11,13-podocarpatrien-7-one (1), a constituent of Taiwania cryptomerioides and Celastrus paniculatus, was achieved starting from (+)-manool (4) after a four-step sequence in 24% overall yield.

Synthesis and antimalarial activities of optically active labdane-type diterpenes.

An efficient method for the synthesis of optically active labdane-type diterpenes from (+)-manool 8 is described. We prepared the natural labdane-type diterpene 5 via key intermediate peroxide 9, and synthetic hydroxybutenolides 6 and 7 via a furan photosensitised oxygenation reaction of labdafuran (14). Compounds 5, 6, 7 and 9 were evaluated as inhibitors of the beta-haematin formation and globin proteolysis, and then were assayed in a malarial murine model. Compound 9 was the most promising compound, showing a positive correlation between in vitro and in vivo activities.

Facile access to optically active labdane-type diterpenes from (+)-manool. Synthesis of (+)-coronarin E, (+)-15,16-epoxy-8(17),13(16),14-labdatriene, and (+)-labda-8(17),13(Z)-diene-15,16-diol.

An efficient method for the synthesis of (+)-coronarin E (1), (+)-15,16-epoxy-8(17),13(16),14-labdatriene (2), and (+)-labda-8(17),13(Z)-diene-15,16-diol (3) from (+)-manool is described.