The structures, names, bioactivities and references of 138 briarane-type diterpenoids, including 87 new compounds, are summarized in this review. All the briarane-type compounds mentioned in this review article were obtained from gorgonian corals including the genus Briareum, Dichotella, Junceella and Verrucella. Some of these compounds showed potential bioactivities.

Two novel diterpenoids, sinularbols A (1) and B (2), which were found to possess a new carbon skeleton were isolated from the soft coral Sinularia arborea. The structures of compounds 1 and 2 were elucidated by spectroscopic methods and 2 displayed a moderately inhibitory effect on the generation of superoxide anion by human neutrophils.

Marine brown alga Dictyota dichotoma (Dictyotaceae) collected from the Karachi coast of the Arabian Sea has yielded three new C-16 oxidized seco-dolastanes (diterpenoids) named dichotenol-A, B and C. Their structures have been characterized with the aid of 2D-NMR spectroscopic techniques.

The exudate of Ozothamnus hookeri has been investigated for its non-flavonoid constituents. A new natural C6-C3 ester of a long chain fatty acid and seven structurally related kaurane-diterpenoids were isolated. Three of the latter are new natural products, too. A rare 8-methoxy flavonol was also identified.

From the bulbils of Dioscorea bulbifera L. var sativa, two clerodane diterpenoids, Bafoudiosbulbins F (1) and G (2), together with five known compounds: Bafoudiosbulbins A–C, 3,5,40-trihydroxy-30-methoxybibenzyl, and kaempferol were isolated. Their structures were established by spectroscopic techniques, Y, COSY he basi as revis

Miltiradiene (1) is the precursor of phenolic diterpenoids such as ferruginol (2), requiring aromatization and hydroxylation. While this has been attributed to a single cytochrome P450 (CYP76AH1), characterization of the rosemary ortholog CYP76AH4 led to the discovery that these CYPs simply hydroxylate the facilely oxidized aromatic intermediate abietatriene (3).

A catalytic enantioselective double allylic alkylation reaction has been employed in the synthesis of the core of the gagunin diterpenoids. Enantioenriched material was advanced in 11 steps to afford the core of the highly oxygenated target, which includes two all-carbon quaternary stereocenters.

Two new briarane diterpenoids briareolate esters J (1) and K (2) were isolated from the methanolic extract of the octocoral Briareum asbestinum collected off the coast of Boca Raton, Florida. The structures of briaranes 1 and 2 were elucidated by interpretation of spectroscopic data. Briareolate ester K (2) showed weak growth inhibition activity against human embryonic stem cells (BG02).

The methanol extract of Brazilian propolis was fractionated by HPLC, based on HuH13 (human hepatocellular carcinoma) cell cytotoxicity assay. Two isomers of diterpenoid with a molecular formula of C20H30O3 (MW: 318.46) were isolated. The structures of these colorless compounds were determined as clerodane diterpenoids (I, 15-oxo-3, 13Z-kolavadien-17-oic acid; II, 15-oxo-3Z, 13E-kolavadien-17-oi...

A new abeo-abietane diterpenoid, 12-methoxy-6,11,14,16-tetrahydroxy-17(15→16)-abeo-5,8,11,13-abietatetraen-3,7-dione (8), was isolated from the hydroalcoholic extract of the herb of Clerodendrum kiangsiense along with seven known diterpenoids (1-7). Their structures were identified on the basis of spectroscopic analyses including two-dimensional NMR and comparison with literature data. All of t...