Lucía S. Andrés

Diterpenes from Salvia mellifera and their biogenetic significance

Abstract The new diterpenes, 11,12-dihydroxy-20-nor-abieta-5(10),8,11,13-tetraen-1-one and isogaldosol, together with the known compounds carnosic acid, carnosol, rosmanol, rosmadial, galdosol and isorosmanol were isolated from the aerial part of Salvia mellifera . The structures of the new diterpenes were established from their spectral data and by chemical correlations. The co-occurrence of all these compounds in one species taken together with their chemical behaviour led to the postulation of a biogenetic pathway to highly oxidized abietatriene diterpenes in which enzymatic dehydrogenation processes and the participation of singlet-state oxygen appear to play an important role.

A first study of antibacterial activity of diterpenes isolated from some Salvia species (Lamiaceae)

Abstract Products from three species of Salvia were tested for activity against Gram-positive Bacillus subtilis and Staphylococcus aureus and Gram-negative Escherichia coli and Salmonella sp. on plates. The more active substances were assayed in liquid medium. The relationship between structure and activity is described.

Structure—antimicrobial activity relationships of abietane diterpenes from Salvia species

Abstract Twenty-one abietatriene diterpenes isolated from Salvia species were evaluated for antimicrobial activity against three strains of bacteria and one yeast. The results obtained show that the free catechol grouping is essential for antimicrobial activity against Gram-positive bacteria and that activity appears to be independent of the closing position of the lactone group in the class A compounds. If there was an extra hydroxyl group at C-6 or C-7, activity was reduced to less than a third, and a hydroxy-methylene group at C-16 also rendered the products ineffective. Compounds where the catechol grouping had been oxidized to a quinone exhibited enhanced activity.

Diterpenes from Salvia mellifera

Abstract 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.

Bioactive Diterpenoids Isolated from Salvia mellifera

Eight diterpenoids were isolated from the roots of Salvia mellifera Greene. Their structures were elucidated by comparison to their physical and spectroscopy data with those reported in the literature or that of authentic samples as: abieta‐8,11,13‐triene, ferruginol, 15‐deoxi‐fuerstione, taxodione, isotanishinone III, rolyeanone, 7αsl‐hydroxi‐rolyleanone and demethylsalvicanol. Demethylsalvican‐11‐12‐dione was obtained by oxidation with Ag2O from demethylsalvicanol. Compounds ferruginol, taxodione, isotanshinone III, and 7αsl‐hydroxi‐royleanone showed cytotoxic activity against both HeLa and Hep‐2 cells in culture. Royleanone and demethylsalvican‐11‐12‐dione were active on Hep‐2 and HeLa cells respectively. Antimicrobial activity against some Gram (+) bacteria was observed for the diterpenoids ferruginol, taxodione, 7α‐hydroxi‐royleanone and demethylsalvican‐11‐12‐dione. None of them was active on Gram (−) bacteria or Candida albicans.

Diterpenes from in vitro-grown Salvia canariensis

Abstract The new diterpene, 16-acetoxycarnosol together with the known compounds, carnosic acid, 11 -acetoxycarnosic acid and carnosol were isolated from seven-day-old in vitro grown plantlets of Salvia canariensis . Neither the new compound nor carnosic acid could be obtained from 25-day-old plantlets which, however, contained 7-methoxyrosmanol.

Phenylphenalenonic phytoanticipins. New acenaphtylene and dimeric phenylphenalenones from the resistant Musa selected hybrid SH-3481

Abstract A new acenaphtylene derivative and two new dimeric phenylphenalenones has been isolated from healthy rhizomes of Musa selected hybrid resistant cultivar SH-3481. The structures of the new substances were elucidated using spectroscopy data. The chemical shift for all the hydrogen and carbon atoms in the substances were unambiguously established by mono and bi-dimensional, homo and heteronuclear NMR experiments. Seven previously reported phenylphenalenone type phytoalexins were also now isolated as constitutive natural antibiotics and so as phytoanticipins from this resistant banana cultivar, suggesting that this type of phytoalexins play an important role as part of the resistance mechanisms to fungal diseases in this important alimentary resource botany family.

C-16 hydroxylated abietane diterpenes from Salvia Mellifera

Abstract The new natural diterpenes, 16-acetoxycarnosic acid, 16-hydroxyrosmanol, 16-hydroxyisorosmanol, 16-hydroxyepirosmanol, 11,12,16,20-tetrahydroxy-abieta-8,11,13-triene, 16-hydroxy-20-deoxocarnosol and 16-hydroxyrosmadial plus the known compounds 16-hydroxycarnosic acid, carnosic acid, carnosol, rosmanol, 7- O -methylrosmanol, isorosmanol, epirosmanol, rosmadial, pisiferal, salvicanol and demethylsalvicanol were isolated from the aerial parts of Salvia mellifera . Cryptotanshinone, obtained from an extract of the roots, provided a point of comparison for the configuration at C- 15. The structures of the new substances were established by spectroscopy and chemical correlations. The absolute configuration at C-15 was assigned to all the new diterpenes on the basis of the most likely biogenetic considerations.

Chemical evidence for the participation of a perepoxide intermediate in the reaction of singlet oxygen with mono-olefins in relationship with the biogenetic pathway to highly oxidized abietane diterpenes

Chemical evidence has been obtained in two separate experiments for the participation of a perepoxide intermediate in the reaction of singlet oxygen with mono-olefins. The intramolecular trapping of such an intermediate in the reaction of 6,7-didehydrocarnosic acid derivatives with molecular oxygen in unequivocal singlet oxygen-generating conditions to give rosmanol and isorosmanol derivatives represents conclusive proof for the cited mechanism. Futhermore, such chemical evidence supports our earlier hypothesis of a biogenetic pathway to highly oxidized abietatriene diterpenes in which enzymatic dehydrogenation and singlet-state oxygen appear to play important roles.

C-16 hydroxylated abietane diterpenes from salvia mellifera. Absolute configuration and biogenetic implications.

Abstract Two new C-16 hydroxylated abietane diterpenes and the known compounds cryptotanshinone and isopimaradiene have now been isolated from Salvia mellifera and identified by rigorous spectroscopic and X-ray crystallographic analyses. Our findings indicate that epoxidation of the monosubstituted double bond of an isopimaradiene precursor must take place before 16-hydroxylated abietanes are formed.