Laila Moujir

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.

Structure and absolute configuration of triterpene dimers from Maytenus scutioides

Abstract Eight new triterpene dimers ( 1–8 ) were isolated from Maytenus scutioides (Celastraceae). Their structures were determined on the basis of spectroscopic evidence and their absolute configurations by means of CD studies. Their possible biogenetic route is discussed. One unnatural dimer was synthesized by a hetero Diels-Alder reaction.

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.

Xanthine oxidase inhibitory activity of some Panamanian plants from Celastraceae and Lamiaceae

Thirty four crude extracts of Panamanian plants, from nine species of Celastraceae and Lamiaceae, were assayed for xanthine oxidase (XO) inhibitory activity. The enzymatic activity was estimated by measuring the increase in absorbance at 290 nm due to uric acid formation. Eighty five percent of the crude extracts were found to possess XO inhibitory activity at 50 micrograms/ml and all the extracts of the species from Lamiaceae were active even at 1 micrograms/ml. The ethanol extracts of Hyptis obtusiflora Presl ex Benth. (Lamiaceae) and H. lantanaefolia Poit. (Lamiaceae) exhibited the highest activity with an inhibition of approximately 40% at 1 micrograms/ml.

The relationship between structure and antimicrobial activity in quinones from the Celastraceae.

Triterpene quinones and related compounds isolated from Schaefferia cuneifolia Standley and Maytenus horrida Reiss were assayed for antimicrobial activity on 18 different bacteria and one yeast. Compounds which had a triterpene quinone skeleton and groups in ring E tested positive, with maximum activity when there was a carboxyl group at C-20. These substances were more or less effective against Gram positive bacteria and the yeast, but did not affect Gram negative bacteria.

Antibiotic phenol nor-triterpenes from Maytenus canariensis

The new phenols 6-oxo-tingenol, 3-O-methyl-6-oxo-tingenol and 6-oxo-iguesterol were isolated from the root bark of Maytenus canariensis. Their structures were determined by 1H and 13C NMR spectroscopic studies, including HMQC, HMBC, DEPT and ROESY and chemical transformations. The synthesis of 6-oxo-tingenol was achieved from tingenone. These compounds exhibit antibiotic activity against Gram-positive bacteria.

Two new triterpene dimers from Celastraceae, their partial synthesis and antimicrobial activity

Abstract Two new triterpene dimers, 7 and 8 , were isolated from Maytenus umbellata and proved to be oxidized structures of tingenone from which they could also be synthesized. These compounds were screened for antimicrobial activity and compared with related compounds.

Withaferin A-related steroids from Withania aristata exhibit potent antiproliferative activity by inducing apoptosis in human tumor cells.

Six new withanolides (1-6) along with eleven known ones (7-17) were isolated from the leaves of Withania aristata. Their structures were elucidated on the basis of spectroscopic analysis, including 1D and 2D NMR techniques. Semisynthesis of the minority metabolites 7 and 15 from compounds 6 and 9, respectively, as starting material, was performed. The isolated compounds as well as three derivatives (7a, 9a and 9b) of withaferin A were evaluated for cytotoxicity against HeLa (carcinoma of the cervix), A-549 (lung carcinoma) and MCF-7 (breast adenocarcinoma) human cancer cell lines, and against normal Vero cells (African green monkey kidney). Five compounds from this series (8, 9a, 9b, 11 and 13) exhibited potent antiproliferative effects on the tumor cells, even higher than the well known anticancer agent, withaferin A (9). Phosphatidylserine externalization, chromatin condensation, and caspase-3 activation clearly indicated apoptosis as a mechanism of action. The structure-activity relationship revealed valuable information on the pharmacophore for withanolide-type compounds.

Absolute configuration of triterpene dimers from Maytenus species (Celastraceae)

Abstract Three new triterpene dimers (1–3) based on two pristimerin units were isolated from Maytenus blepharodes and Maytenus magellanica. Their structures were elucidated on the basis of spectral analysis, including homonuclear and heteronuclear correlation NMR experiments (COSY, ROESY, HSQC and HMBC). Their absolute configurations were determined by CD studies. The compounds were assayed for antimicrobial and cytotoxic activities.