Jorge Triana

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).

ent-Labdane Diterpenoids from the Aerial Parts of Eupatorium obtusissmum

Six new ent-labdane diterpenoids, uasdlabdanes A-F (1-6), were isolated from the aerial parts of Eupatorium obtusissmum. The new structures were elucidated through spectroscopic and spectrometric data analyses. The absolute configurations of compounds 1 and 2 were established by X-ray crystallography, and those of 3-6, by comparison of experimental and calculated electronic circular dichroism spectra. The antiproliferative activity of the compounds was studied in a panel of six representative human solid tumor cell lines and showed GI50 values ranging from 19 to >100 μM.

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.

Germacranolides from Allagopappus viscosissimus

Abstract Five germacranolides related to the ineupatorolides have been obtained from the aerial part ofAllagopappus viscosissimus as well as known flavonoids and other compounds. A close relationship between this genus and other members of the same subtribe is indicated.

Sesquiterpenoids Isolated from Two Species of the Asteriscus Alliance

Investigation of the aerial parts of two Spanish members of the Asteriscus alliance, Asteriscus graveolens subsp. stenophyllus and Asteriscus schultzii, afforded four new sesquiterpene lactones containing a humulene skeleton (1-4) and one new sesquiterpene lactone of the asteriscanolide type (5). Their chemical structures were determined on the basis of the HRMS and from 1D and 2D NMR spectroscopic studies. Both species showed different profiles of sesquiterpenoid constituents. A. schultzii did not show humulene or asteriscane sesquiterpenes, suggesting a resemblance to the genus Pallenis, another member of the Asteriscus alliance. A literature review on chemical isolates from the Asteriscus alliance supported the placement of A. schultzii in the genus Pallenis. The isolated components (1-5) were assessed for cytotoxicity against the HL-60 and MOLT-3 leukemia cell lines, with compound 1 showing activity in both biological assays (IC50 value range 4.1-5.4 μM).

Ayanin diacetate-induced cell death is amplified by TRAIL in human leukemia cells

Here we demonstrate that the semi-synthetic flavonoid ayanin diacetate induces cell death selectively in leukemia cells without affecting the proliferation of normal lymphocytes. Incubation of human leukemia cells with ayanin diacetate induced G(2)-M phase cell cycle arrest and apoptosis which was prevented by the non-specific caspase inhibitor z-VAD-fmk and reduced by the overexpression of Bcl-x(L). Ayanin diacetate-induced cell death was found to be associated with: (i) loss of inner mitochondrial membrane potential, (ii) the release of cytochrome c, (iii) the activation of multiple caspases, (iv) cleavage of poly(ADP-ribose) polymerase and (v) the up-regulation of death receptors for TRAIL, DR4 and DR5. Moreover, the combined treatment with ayanin diacetate and TRAIL amplified cell death, compared to single treatments. These results provide a basis for further exploring the potential applications of this combination for the treatment of cancer.

Secondary Metabolites from Two Species of Pulicaria and Their Cytotoxic Activity

Two new compounds, the sesquiterpene (1E,5E)‐8β‐acetoxy‐4α‐hydroxy‐7βH‐germacra‐1(10),5‐dien‐14‐oic acid (2), and a nor‐sesquiterpene, (5E)‐8β‐acetoxy‐4α‐hydroxy‐7βH‐germacr‐5‐en‐10‐one (3), were isolated from Pulicaria canariensis ssp. lanata, along with ten known compounds, including the flavonoid 5,3′‐dihydroxy‐3,7,4′‐trimethoxyflavone (4). From Pulicaria burchardii, we isolated seven known compounds; the physical and spectroscopic data of the triterpenoid 3β‐hydroxytaraxaster‐20‐en‐30‐al (1) are reported. The structures of compounds 1–3 were determined on the basis of HR‐MS, and 1D‐ and 2D‐NMR studies. The structure of 2 was corroborated by X‐ray crystal diffraction. Cell viability experiments revealed that the semisynthetic flavonoid 4b was the most cytotoxic compound against human leukemia cells, and the cytotoxicity was caused by induction of apoptosis, as determined by microscopy of nuclear changes.

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.

Secondary metabolites from two Hispaniola Ageratina species and their cytotoxic activity

Study of the aerial parts of the two species of Ageratina: A. dictyoneura and A. illita afforded four new ent-labdane diterpenoids (1–4). Two known labdanes: 2β,3α,15-trihydroxy-ent-labd-7-ene (5), and 2β,3α-trihydroxy-ent-labd-7-en-15-oic acid (6); two sesquiterpene lactones: 8β-hydroxy-β-cyclocostunolide (7) and eupatoriopicrin (8), one benzofuran, and six flavonoids were also isolated. Their chemical structures were determined based on extensive spectroscopic study, comparison with reported data and chemical transformations. The cytotoxicity of the new ent-labdane diterpenoids 1–3, sesquiterpene lactone 7, and the flavonoid: quercetin 3,7-dimethylether were assessed against the human myeloid leukemia U-937 cell line and found that compound 7 and quercetin 3,7-dimethylether were cytotoxic against this cell line.