Cecilia Labbé

Bakuchiol derivatives from the leaves of Psoralea glandulosa

Four new meroterpene derivatives have been isolated in a bioassay-guided study of the methanol extract of the leaves of Psoralea glandulosa, in addition to the known compounds bakuchiol and angelicin. Structures for the new compounds are proposed on spectroscopic evidence. The results of brine shrimp (Artemia salina) and disc-choice (Spodoptera littoralis) bioassays are interpreted in terms of the structural features.

Mono and sesquiterpenoids from Satureja gilliesii

Abstract Two new isomeric monoterpene peroxides along with (+)-T-cadinol and (−)-cadin-4-en-1-o1 were isolated from the leaves of Satureja gilliesii (Lamiaceae). Significant toxicity toward Artemia salina (brine shrimp bioassay) was observed for the cadinane sesquiterpenoids.

Tetranortriterpenoids and related compounds. Part 22. New apotirucailol derivatives and tetranortriterpenoids from the wood and seeds of chisocheton paniculatus(meliaceae)

Five new compounds, the apo-tirucallol derivatives (1), (9), (13), and (16) and the tetranortriterpenoid vilasinin 1,3-diacetate (18), have been isolated from the wood of Chisocheton paniculatus(Meliaceae). From the seeds of the same tree four new tetranortriterpenoids have been obtained, including the γ-lactone (22), the hemiacetal (23), the γ-hydroxybutenolide (24), and 17β-hydroxy-6α-acetoxynimbinin (26). Compounds (22) and (23) are possible precursors of normal furanoid tetranortriterpenoids. 13C and 1H n.m.r. Data for these nine compounds are reported.

Jatropholones A and B, new diterpenoids from the roots of (euphorbiaceae) - crystal structure analysis of Jatropholone B.

From the roots of Jatropha gossypiifolia (Euphorbiaceae) we have isolated two new diterpenoids, jatrophalone A (1), C20H24O2, and its C-2 epimer jatropholone B, with a cyclised casbene skeleton incorporating a fully substituted cresol ring. The structure of jatropholone B was established as (2) by a crystal-structure analysis of the corresponding acetate (3).

Seasonal changes in chemical composition of epicuticular waxes from the leaves of Baccharis linearis

Abstract Extracts from the epicuticular waxes of leaves from Baccharis linearis collected at the same locality at different seasons of the year were compared in terms of relative yields, chemical composition and biological activity (feeding deterrancy against Spodoptera littoralis larvae and brine shrimp lethality bioassays). Variations detected in the concentration of some of the 13 secondary metabolites isolated in this study are discussed in connection with relevant seasonal changes of incidental environmental factors such as temperature, solar radiation, water stress and presence of predatory insects.

Tropane alkaloids from Schizanthus grahamii

Abstract Three new tropanol dimers of mesaconic and itaconic acids and 3α-senecioyloxytropane, together with other known alkaloids, were isolated from Schizanthus grahamii . The structures of the new compounds were established by spectroscopic and chemical transformations including 2-D long-range 13 C- 1 H correlations.

Tetranortriterpenoids and related substances. Part 20. New tetranortriterpenoids from the seeds of Chukrasia tabularis(Meliaceae); simple esters of phragmalin and 12α-acetoxyphragmalin

Four new tetranortriterpenoids isolated from the light petroleum extract of the seeds of Chukrasia tabularis(Meliaceae) have been identified as the 3,30-di-isobutyrates (1) and (2) and the 3-isobutyrate 30-propionates (3) and (4) of phragmalin and 12α-acetoxyphragmalin. Two compounds (12) and (13) with a modified furan ring were also obtained from the extract.

Clerodane diterpenoids and an ursane triterpenoid from Salvia haenkei. Computer-assisted structural elucidation

Abstract Five ent-clerodane diterpenoids, four new, and a new ursane triterpenoid have been isolated from Salvia haenkei collected in Bolivia. The structures of two ent-clerodanes ent-(4S,5R)-7α-acetoxy-15,16-epoxy-10-oxo-9,10-secocleroda-1,8,13(16),14-tetraene-17,12S,18,19-diolide1 (salvianduline B) and ent-(5R,9R)-15,16-epoxy-10S-hydroxy-cleroda-3,7,13(16),14-tetraene-17,12S,18,19-diolide 2, were elucidated from HMQC and HMBC data using an automatic structure elucidation computer program. The structures of the other clerodanes, ent-(5R,9R)-15,16-epoxy-10S-hydroxy-cleroda-3,13(16),14-triene-17,12S,18,19-diolide6, ent-(4S,5R,9S,10R)-15,16-epoxycleroda-1,13(16),14-triene-17,12S,18,19-diolide 7 and ent-(5R,9R,10S)-7S-acetoxy-15,16-epoxy-1S,2S,12 Gx-trihydroxycleroda-3,13(16),14-trien-18,19-olide8, were derived in the usual manner from 1H and 13C NMR data. The stereochemistry of 2 was confirmed by an X-ray crystal structure analysis. The triterpenoid is 3-oxours-12-ene-1β,11α-diol 9.

Chemistry, toxicity and antifeedant activity of the resin of Flourensia thurifera

The resin extract from leaves and stems of Flourensia thurifera displayed high levels of activity in the brine shrimp (Artemia safina) and antifeedant disk-choice (Spodoptera littorafis) bioassays. A bioassay-guided fractionation of the extract led to the isolation of nine known aromatic compounds (1–9) including coumarins, chromenes, a benzofuran, a flavonoid and p-coumaric acid derivatives. The results of bioassays on the pure compounds are discussed.

Angeloyl, tigloyl and senecioyloxytropane alkaloids from Schizanthus hookerii

Abstract 6β-Angeloyloxytropan-3α-ol, 3α-senecioyloxytropan-6β-ol and 6β-tigloyloxytropan-3α-ol, tropine and two diasteromeric hygrolines were isolated from Schizanthus hookerii .