Two minor diterpenes related to dictyodial A from the brown alga Dictyota crenulata

4β-Hydroxydictyodial A and 18,O-dihydro-4β-hydroxydictyodial A 18-acetate are two minor aldehydic diterpenes in the brown alga Dictyota crenulata. ¹H NMR and lanthanide-induced chemical shift studies indicate that the relative stereochemistry of both compounds is 2R*, 3R*, 4S*, 10S*.     

Diterpenes from Heteropappus altaicus

The aerial parts of Heteropappus altaicus afforded, in addition to more widespread compounds and known clerodane derivatives, three new ones and a seco-clerodane acid. Furthermore, a neryl geraniol derivative was present. The structures were elucidated by spectroscopic methods. The stereochemistry was solved by NOE difference spectroscopy and by the Horeau method.     

Carbohydrates of the brown seaweed Dictyota dichotoma

The fucose-containing polysaccharides of the brown alga Dictyota dichotoma were extracted with either trichloroacetic acid or HCl to give both water-soluble and water-insoluble materials. The latter had a high proportion (16 to 11%) of protein, and although all the sugars found in the water-soluble extracts were present, the major sugar in these water-insoluble polysaccharides was glucose. The water-soluble material extracted with HCl was a protein-free sulphated heteropolysaccharide. Complete removal of a glucan from the water-soluble extract was achieved by fractional precipitation with ethanol. The recovered glucan-free sulphated polysaccharide, which was rich in glucuronic acid, galactose, fucose and sulphate, showed high anticoagulating activity.     

Diterpenes from Marrubium sericeum, Marrubium supinum and Marrubium alysson

From some Marrubium species endemic in the Iberian Peninsula, four new diterpenoids, 6-acetyl-marrubenol, 19-acetyl-marrubenol, premarrubenol and 6-acetyl-premarrubenol, have been isolated. The previously known diterpenes marrubiin and marrubenol have also been obtained from the same sources.     

Diterpenes from the seed of Sciadopitys verticillata

Thirteen new labdane-type diterpenes have been isolated from the seeds of Sciadopitys verticillata together with six known ones, sciadin, sciadinone, dimethyl sciadinonate, lambertianic acid and its methyl ester and trans-communic acid. Their structures have been determined by chemical and spectral methods.     

Diterpenes of Larix oleoresins

Oleoresins from most species of the genus Larix have been analysed by GLC for their diterpene composition. Common to all are the abietadiene and isopimaradiene acids usual in Pinaceae with the corresponding aldehydes and alcohols in small amounts. Epimanool also occurs in all, but larixol and its acetate is confined to L. decidua and L. gmelini, and epitorulosol to the remainder. In the hybrid L. Xeurolepis both of these last two compounds are present.     

Diterpenes from the roots of Salvia canariensis

The new diterpenes, deoxocarnosol 12-methyl ether, salvicanol and 6α-hydroxydemethylcryptojaponol, and the known ones, sugiol and demethylcryptojaponol, have been isolated from the bark of the roots of Salvia canariensis.     

Diterpenes from Salvia mellifera

Two new aromatic diterpenes have been obtained from the aerial part of Salvia mellifera and their structures identified, on the basis of spectral data and chemical correlations, as 11,12,20-trihydroxy-abieta-8,11,13-triene and 11,12,16-trihydroxy- abieta-8,11,13-trien-20-al. The known diterpenes, carnosic acid, carnosol, rosmanol, isorosmanol, galdosol, rosmadial, 9 (10 → 20)-abeo-abieta-8,11,13-triene-10β,11,12-triol (demethylsalvicanol)and salvicanol were also isolated from the same source. The absolute configuration of salvicanol was established by X-ray diffraction analysis of its 11-p-bromobenzoate derivative.     

Diterpenes with pimarane and cleistanthane skeletons from Vellozia piresiana

Vellozia piresiana contains β-sitosterol, stigmasterol, taraxerone, compactone, 7β,8β-dihydroxy-3-oxopimar-15-ene and three new diterpenes, one of the pimarane type and the other two with a cleistanthane skeleton. Their structures were deduced on the basis of spectral data and chemical modifications.     

Diterpenes and sesquiterpene lactones from Mikania congesta

The chloroform extract of the aerial parts of Mikania congesta, afforded four new geranylnerol derivatives, new analogs of deoxyelephantopin, a new melampolide and several known compounds. Structures were elucidated by spectroscopic methods and chemical transformations.     

Diterpenes of Podocarpus ferrugineus bark

The following oxygenated diterpenes have been isolated from the bark of Podocarpus ferrugineus D. Don: isopimarol, isopimaric acid, sandaracopimaric acid, ferruginol, sugiol, sugiyl methyl ether, xanthoperol, royleanone, 6-dehydroroyleanone, cryptojaponol, 5β-hydroxy-6-oxasugiyl methyl ether, 2-ketoferruginol and 2β-acetoxysugiyl methyl ether.     

Cassane Diterpenes from Caesalpinia bonduc

Three cassane diterpene hemiketals, caesalpinolide-C, caesalpinolide-D, caesalpinolide-E and one cassane furanoditerpene were isolated from Caesalpinia bonduc. The molecular structures were elucidated using NMR spectroscopy in combination with IR, UV and mass spectral data and relative stereochemistries were determined through ROESY correlation. The isolated compounds were tested for their antiproliferative activity against MCF-7 (breast adenocarcinoma), DU145 (prostate carcinoma), C33A (Cervical carcinoma) and Vero (African green monkey kidney fibroblast) cells.     

Diterpenes from Baccharis species

The aerial parts of Baccharis minutiflora afforded in addition to known compounds eight new ent-kaurane derivatives, one being a homo kaurane, while the aerial parts of B. alatemoides gave two pairs of epimeric clerodane derivatives, which, however, had to be modified chemically before they could be separated. The stereochemistry of these diterpenes could not be elucidated with certainty.     

Diterpenes from Koanophyllon species

The investigation of two Koanophyllon species afforded, in addition to known compounds, several new diterpenes, two new geranylgeraniol derivatives and four diterpenes, most probably closely related to clerodanes; their structures, however, could not be deduced with certainty. The chemotaxonomic situation of this genus is discussed briefly.     

Diterpenes from Baccharis species

The investigation of ten Baccharis species afforded in addition to known compounds eight new diterpenes, four ent-labdanes, three kaurenes and a clerodane derivative. Furthermore, two new p-hydroxyacetophenones, a flavone, 3′-methoxyxanthomicrol and two matricaria ester derivatives were isolated. The structures were elucidated by spectroscopic methods and a few chemical transformations. The chemotaxonomic situation of the large genus is discussed briefly.     

Diterpenoids from Baccharis tola

Erythroxylol-A, oleanolic acid, erythroxylol-A oxide, scopolatine, 4-hydroxy-3-methoxyacetophenone and two new diterpenes, ent-beyer-14-en-18-ol and 19-hydroxy-13-epimanoyl oxide, were isolated from B. tola.     

Ent-Labdanes from Baccharis Sternbergiana

The aerial parts of Baccharis sternbergiana afforded six new ent-labdane derivatives, while those of a Baccharis tricuneata subspecies gave 12-acetoxytremetone.