Veliah Chelladurai

Stilbenoids in the stem bark of Hopea parviflora.

From the bark of Hopea parviflora, two stilbenoids, named (+)-parviflorol and (-)-ampelopsin A, were isolated in addition to three known compounds: (+)-balanocarpol, (-)-epsilon-viniferin and (-)-hopeaphenol. Their structures were determined by analysis of spectral data, including 2D NMR and NOE experiments, respectively.

Two new oligostilbenes with dihydrobenzofuran from the stem bark of Vateria indica

Abstract Two new stilbenoids, vateriaphenols A ( 1 ) and B ( 2 ), were isolated from the stem bark of Vateria indica along with known 10 stilbenoids ( 3–12 ) and bergenin ( 13 ). The structures of isolates were established based on spectroscopic analysis. The structures of vateriaphenols A and B were characterized as an octamer and a tetramer of resveratrol, respectively. The spectral properties of the highly condensed vateriaphenol A were also discussed.

Six xanthones from Calophyllum austroindicum

Abstract Six new xanthones, caloxanthone F, G, H, 6-hydroxy-1,3,5-trimethoxy-, 3,6-dihydroxy-1,5-dimethoxy- and 1,3,6-trihydroxy-5,7-dimethoxyxanthone, were isolated from the stem wood of Calophyllum austroindicum , in addition to eight known xanthones. From the bark, four known xanthones, a coumarin, apetallic acid, and (−)-epicatechin were isolated. These structures were determined by analysis of NMR spectral data including 2D techniques.

Prenylated xanthonoids from Calophyllum apetalum

Abstract Three new xanthonoids, apetalinones A-C, were isolated from the roots of Calophyllum apetalum, as well as the known compounds, calozeyloxanthone and zeyloxanthonone. The stem bark of this species yielded a new xanthonoid, apetalinone D, and another known xanthonoid, tomentonone. Five known xanthones (3,8-dihydroxy-1,2-dimethoxy-, 1,3-dihydroxy-2,5-dimethoxy-, 1,5-dihydroxy-, 1,3,5-trihydroxy-2-methoxy- and 1,3,5-trihydroxyxanthone) and two flavonoids ((−)-epiafzelechin and (−)-epicatechin) were also characterized as constituents in the stem wood. Among them, apetalinone A was a novel xanthone with 1,1-dimethylallyl ether moiety, which indicated a new biosynthetic pathway including Claisen rearrangement and Diels-Alder reaction.

A xanthone from Garcinia cambogia

As a chemical constituent of Garcinia cambogia, a new xanthone, garbogiol, was isolated from the root; a known xanthone (rheediaxanthone A) and two known benzophenones (garcinol and isogarcinol) were obtained from the bark. The structures were established by spectral analysis.

Three xanthones from Poeciloneuron pauciflorum and Mammea acuminata

Abstract From the stem of Poeciloneuron pauciflorum , two new xanthones (1,6-dihydroxy-7-methoxyxanthone and 1,6-dihydroxy-7-methoxyxanthone 6-O-β- d -glucoside ) in addition to 12 known compounds (1,5-dihydroxy-, 1,5-dihydroxy-3-methoxy-, 1,7-dihydroxy-, 1-hydroxy-7-methoxy-, 2-methoxy-, 4-methoxy-, 1,4,5-trihydroxy-, 1,3,5-trihydroxy-, 1,3,6-trihydroxy-7-methoxy-, 1,3,7-trihydroxy-, 3-hydroxy-2-methoxyxanthone and (−)-epicatechin) were isolated. From the aerial parts (stems and bark) of Mammea acuminata , a new xanthone (2,7-dihydroxyxanthone) was isolated in addition to two known xanthones (1,5-dihydroxy- and 5-hydroxy-1-methoxyxanthone) and (−)-epicatechin. The structures were established by spectral analysis and total synthesis in case of 1,6-dihydroxy-7-methoxyxanthone.