Centaurea microcarpa Coss. & Dur. (Asteraceae) extracts: New cyanogenic glucoside and other constituents.

The phytochemical investigation of both chloroform and ethyl acetate extracts of Centaurea microcarpa Coss. & Dur. led to the isolation of a new cyanogenic glucoside 6'-methacrylate prunasin (3) together with seven known compounds: hydroxy-11ß,13-dihydro onopordaldehyde (1), ß-sitosterol (2), daucosterol (4), nepetin (5), prunasin (6), astragalin (7) and 7-O-ß-D-glucopyranosyl centaureidin (8). Their structures were established by spectral analysis, mainly UV, IR, ESI-MS, 1D & 2D-NMR experiments (COSY, HSQC, HMBC and ROESY).

Secondary metabolites from two species of Tolpis and their biological activities.

Phytochemical research of two Tolpis species, T. proustii and T. lagopoda, led to the isolation of three new compounds: 30-chloro-3β-acetoxy-22α-hydroxyl-20(21)-taraxastene (1), 3β,22α-diacetoxy-30-ethoxy-20(21)-taraxastene (2) and 3β,28-dihydroxy-11α-hydroperoxy-12-ursene (3). The structures of the new compounds were elucidated by means of extensive IR, NMR, and MS data and by comparison of data reported in the literature. The in vitro antioxidant activities of the extracts were assessed by the DPPH and ABTS scavenging methods. The cytotoxicity of several known compounds and its derivatives was also assessed against human myeloid leukemia K-562 and K-562/ADR cell lines.

Chemotaxonomy of Gonospermum and related genera.

Aerial parts of Gonospermum fruticosum collected at several locations in the Canary Islands afforded, in addition to known compounds, four sesquiterpene alcohols related to costol and a sesquiterpene lactone, whose structures were established on the basis of their spectroscopic data and chemical transformations. Except for Gonospermum species collected on the island of Tenerife, those collected on the island of El Hierro and, in a previous study those from La Gomera, contain sesquiterpene lactones that can be used as chemotaxonomic markers confirming the inclusion of Gonospermum, Lugoa, and species of Tanacetum endemic to the Canary Islands in a genus that does not support the monophyly of Gonosperminae.

Chemical constituents of Tolpis species.

Phytochemical research of two Tolpis species, T. webbii and T. sp., led to the isolation of three new compounds: 2,4'-dihydroxy-4-methoxybenzophenone (1) and the triterpenes 21 alpha, 22 alpha-epoxy-20 alpha-hydroxy-20(30)-dihydrotaraxasterol (2) and 3beta-hydroxytaraxaster-20-en-30-oic acid (3) together with 16 known compounds. The structures of the new compounds were elucidated by means of extensive IR, NMR, MS and X-ray analysis and by comparison of data reported in the literature.

Sesquiterpene lactones from Gonospermum gomerae and G. fruticosum and their cytotoxic activities.

Four new sesquiterpene lactones (1-4) and a new sesquiterpene (5) together with 20 known compounds were isolated from two Gonospermum species (G. gomerae Bolle and G. fruticosum Less). Their structures were determined by analysis of spectroscopic data, including 1D and 2D NMR. The cytotoxicity of several new and known natural and semisynthetic sesquiterpene lactones was also assessed against human myeloid leukemia cell lines (HL-60 and U937), human melanoma cells (SK-MEL-1), and human adenocarcinoma (A549).

A new lupene triterpenetriol and anticholinesterase activity of Salvia sclareoides.

A new lupene triterpenetriol was isolated from the acetone extract of the aerial parts of Salvia sclareoides and characterised as (1beta,3beta)-lup-20(29)-ene-1,3,30-triol (1). In addition, nepetidin (2), nepeticin (3), lupendiol (4), (1beta,11alpha)-dihydroxy-lup-20(29)-en-3-one (5), ursolic acid (6), sumaresinolic acid (7) and hederagenin (8), were identified in this Salvia sp. To the best of our knowledge, the compounds 2 and 7 are new constituents in Salvia spp. The acetone, ethanol, butanol and water extracts of the plant were screened for the in vitro inhibitory activity of acetylcholinesterase (AChE) and butyrilcholinesterase (BChE), enzymes which play a role in the Alzheimer disease. All extracts inhibited acetylcholinesterase activity at 10 microg/ml, a remarkable activity since the standard drug rivastigmine does not inhibit acetylcholinesterase at the same concentration. Regarding the butyrilcholinesterase, the acetone extract at 1000 microg/ml was able to inhibit completely the enzyme activity and the butanol and ethanol extracts, at this concentration, produced a potent inhibition of BchE.