Leslie J. Harrison

Phenanthrenes, dihydrophenanthrenes and bibenzyls from the orchid bulbophyllum vaginatum

Two new phenanthrenes (4,9-dimethoxyphenanthrene-2,5-diol and 4,6-dimethoxyphenanthrene-2,3,7-triol) and two new 9,10-dihydrophenanthrenes (4-methoxy-9,10-dihydrophenanthrene-2,3,7-triol and 4,6-dimethoxy-9,10-dihydrophenanthrene-2,3,7-triol), along with six known phenanthrenes, four known 9,10-dihydrophenanthrenes no known bibenzyls and the triterpenoid friedelin were isolated and characterized from the hexane extract of the orchid Bulbophyllum vaginatum. The structures of these compounds were determined by spectroscopic analyses.

Triterpenoids, tocotrienols and xanthones from the bark of Cratoxylum Cochinchinense

Abstract A novel bicyclic triterpenoid, polypoda-8(26),13,17,21-tetraen-3β-ol, as well as friedelin, three known tocotrienols, four known xanthones (mangostin, β-mangostin, garcinone D and tovophyllin A) and the previously unreported 2-geranyl-1,3,6-trihydroxy-4-(3,3-dimethylallyl)-xanthone and cratoxylone (1,3,6-trihydroxy-2-(3-hydroxy-3-methylbutyl)-7-methoxy-8-(3,3-dimethylallyl)-xanthone) have been isolated from the bark of Cratoxylum cochinchinense . The structures of the new compounds were determined using a combination of spectroscopic and chemical methods.

Xanthones from the heartwood of Garcinia mangostana

Twelve xanthones were isolated from the hexane extract of the heartwood of Garcinia mangostana from Myanmar. Their structures were determined using 1D and 2D NMR techniques

Phenanthrene and other aromatic constituents of Bulbophyllum vaginatum

Abstract Two new phenanthrenes (4-methoxyphenanthrene-2,3,7-triol and 4-methoxyphenanthrene-2,3,6,7-tetrol) and two new 9,10-dihydrophenanthrenes (5-methoxy-9,10-dihydrophenanthrene-2,3,7-triol and 4-methoxy-9,10-dihydrophenan-threne-2,3,6,7-tetrol), along with the known 4,6-dimethoxyphenanthrene-2,3,7-triol and its 9,10-dihydro derivative, 3,4′,5-trihydroxy-3′-methoxybibenzyl (tristin), dihydroferulic acid, p -coumaric acid, 3,4-dihydroxybenzoic acid and (±)-syringaresinol were isolated from the dichloromethane extract of the orchid Bulbophyllum vaginatum . The structures of these compounds were determined through spectroscopic analysis.

Minor xanthones from the bark of cratoxylum cochinchinense

Abstract Three new xanthone derivatives, 11-hydroxy-1-isomangostin, a xanthonolignoid (5′-demethoxycadensin G) and a bisxanthone, as well as the known compound 1,3,5,6-tetrahydroxyxanthone, were isolated from the bark of Cratoxylum cochinchinense. Their structures were elucidated mainly by a combination of high-field NMR spectroscopic techniques.

Triterpenoid and xanthone constituents of Cratoxylum cochinchinense

Abstract Two new compounds, the triterpenoid (13 E ,17 E )-polypoda-7,13,17,21-tetraen-3β-ol and the xanthone E -7-geranyloxy-1,3,7-trihydroxyxanthone have been isolated from the bark of Vietnamese Cratoxylum cochinchinense . The known compounds lupeol, β-mangostin, 2-geranyl-1,3,7-trihydroxy-4-(3-methylbut-2-enyl)xanthone and 1,3,7-trihydroxy-2,4-di(3-methylbut-2-enyl)xanthone were also obtained.

(20R,23E)-Eupha-8,23-diene-3β,25-diol from Tripetalum cymosum

Abstract A new euphane triterpenoid, (20 R ,23 E )-eupha-8,23-diene-3β,25-diol, was isolated from the leaves of Tripetalum cymosum and its structure was determined by spectral analysis and chemical correlation with euphol. Caryophyllene oxide, friedelin, euphol and putranjivic acid were also obtained from the leaves whilst the bark afforded euphol, glutin-5-en-3β-ol, butyrospermol and dammara-20,24-dien-3β-ol.

Griffipavixanthone, a novel cytotoxic bixanthone from Garcinia griffithii and G. pavifolia

Abstract A bioactivity-directed fractionation of the extracts of the Malaysian plant Garcinia pavifolia and a phytochemical study of G. griffithii led to the discovery of griffipavixanthone ( 1 ), a novel cytotoxic bixanthone with cyclized prenyl groups providing the xanthone-xanthone linkage. Spectroscopic data and preparation of methylated derivatives allowed for the complete structural elucidation of 1 .

A dihydrochalcone from Lindera lucida

Abstract A new dihydrochalcone, 3′,5′-dihydroxy-2′,4′,6′-trimethoxydihydrochalcone and five known compounds, methyl linderone, 5-hydroxy-6,7,8-trimethoxyflavone (alnetin), 2′-hydroxy-3′,4′,5′,6′-tetramethoxydihydrochalcone (dihydrokanakugiol), 2′-hydroxy-3′,4′,5′,6′-tetramethoxychalcone (kanakugiol) and 2′,3′,4′,5′,6′-pentamethoxychalcone (pedicellin) were isolated from twigs of Lindera lucida. The structures of these compounds were determined by spectral analyses and chemical correlations.

Ent-trachylobane diterpenoids from the liverwort Mastigophora diclados

Abstract The Malaysian liverwort Mastigophora diclados afforded ent -trachyloban-18-oic acid, ent -trachyloban-19-oic acid and the novel ent -18-hydroxytrachyloban-19-oic acid. The compounds were identified using 1 H and 13 C NMR spectroscopy.