Sarath P. Gunasekera

Terpenes of Dipterocarpus and Doona species

Abstract From the resins of Dipterocarpus hispidus, Dipterocarpus zeylanicus and Doona macrophylla, asiatic (2α,3β,23α-trihydroxyurs-12-en-28-oic) and 2α,3β-dihydroxyurs-12-en-28-oic acids have been isolated. The resin of Doona macrophylla contains ursolic acid and that of Doona congestiflora asiatic acid, 20β-hydroxy-3-oxo dammar-23-ene (Dipterocarpol) and a dihydroxyolean-12-en-28-oic acid. The bark of Dipterocarpus hispidus contains betulinic acid, dipterocarpol, and 3β,20β-dihydroxydammar-23-ene (dammarenediol 20S) whilst the timber contained dipterocarpol and asiatic acid.

Triterpenoids and steroids of some Sapotaceae and their chemotaxonomic significance

Abstract Extraction of the bark and timber of four Madhuca and five Palaquium species has yielded β-amyrin, β-amyrin acetate, β-amyrin cinnamate,

Two new xanthones, calozeyloxanthone and zeyloxanthonone, from Calophyllum zeylanicum(Guttiferae)

Two new xanthones, calozeyloxanthone (1) and zeyloxanthonone (4), have been isolated from the bark of C. zeylanicum as well as betulinic acid, friedelan-3β-ol, calabaxanthone, taraxerone, friedelin, taraxerol, and β-sitosterol. Zeyloxanthonone (4) is identical with wightianone and the structure of the latter is revised. The timber of C. zeylanicum yielded 6-deoxyjacareubin (11), 1,6-dihydroxy-5-methoxyxanthone, 1,5-dihydroxyxanthone, 1,7-dihydroxyxanthone, 2-hydroxyxanthone, and jacareubin.

Chemical investigation of ceylonese plants. Part 27. Extractives of Calophyllum cuneifolium Thw. and Calophyllum soulattri Burm. f. (Guttiferae)

The bark and timber extractives of C. cuneifolium Thw. and C. soulattri Burm. f. have been studied. The bark extract of C. cuneifolium Thw. yielded calabaxanthone (1), trapezifolixanthone (2), taraxerol, simiarenol, friedelin, and a solid bark acid identified as isoapetalic acid (4a). The timber extract yielded 1,3,5-trihydroxy-2-(3-methylbut-2-enyl)xanthone (6a), six known xanthones, and β-sitosterol. The bark extract of C. soulattri Burm f. gave a new coumarin alcohol, soulattrolide (13a), taraxerol, taraxerone, and β-sitosterol. The timber extract afforded four known xanthones and the trihydroxyxanthone (6a).

Chemical investigation of ceylonese plants. Part XVI. Extractives of Calophyllum cordato-oblongum Thw. (Guttiferae)

From the bark of Calophyllum cordato-oblongum Thw. the new resin acid, cordato-oblongic acid (Ia) was isolated and identified as 3-(6,7-dihydro-5-hydroxy-2,2,trans-7,8-tetramethyl-6-oxo-2H,8H-benzo[1,2-b:5,4-b′]-dipyran-10-yl)butyric acid. The timber extract contained the known xanthones 2-hydroxyxanthone (VIII), scriblitifolic acid (X), 1,5,6-trihydroxyxanthone (VIIb), 1,6-dihydroxy-5-methoxyxanthone (VIIa), and jacareubin (XV), and the two new xanthones 3-hydroxy-4-methoxyxanthone (IXa) and cordato-oblonguxanthone (XIII){identified as 1,2-dihydro-6-hydroxy-3,3-dimethylpyrano[2,3-a]xanthen-12(3H)-one}. Friedelin and β-sitosterol were isolated from both extracts.

Chemical investigation of Ceylonese plants. Part XV. Extractives of Kayea stylosa Thw. (Guttiferae)

From the bark extract of Kayea stylosa Thw., taraxerol (Ia), simiaren-3β-ol (IIa), betulinic acid (III), β-sitosterol, and the new xanthones 10-O-methylmacluraxanthone {12-(1,1-dimethylprop-2-enyl)-5,9-dihydroxy-10-methoxy-2,2-dimethyl-2H-pyrano[3,2-b]xanthen-6-one}(IVa) and kayeaxanthone {11-(1,1-dimethylprop-2-enyl)-9-hydroxy-8,10-dimethoxy-2,2-dimethyl-2H-pyrano[2,3-d]xanthen-7-one}(VIIIa) have been isolated and their structures established. The timber extract contained only 1,3,5-trihydroxy-2-methoxyxanthone (VIa) and β-sitosterol.

Chemical investigation of Ceylonese plants. Part 20. Extractives of Mesua myrtifolia. Isolation and structure of a new triterpene hydroxy-acid, myrtifolic acid

From the bark extractives of Mesua myrtifolia(a Malaysian species) simiarenone, simiarenol, taraxerol, betulinic acid, and a new triterpene acid, myrtifolic acid, have been isolated. The latter has been correlated with bauerene and identified as 3α-hydroxybauer-7-en-28-oic acid. From the timber extractives myrtifolic acid, oleanolic acid, and jacareubin have been obtained.

Chemical investigation of ceylonese plants. Part 22. Extractives of Trichadenia zeylanica Thw. (Flacourtiaceae); isolation and structures of six new triterpenoids containing the friedelane skeleton

From the bark and wood extracts of Trichadenia zeylanica Thw., six new triterpenoids, namely trichadenic acid A (3α-hydroxyfriedelan-26-oic acid), O-acetyltrichadenic acid A, O-acetyltrichadenic acid B (3β-acetoxyfriedelan-26-oic acid), trichadonic acid (3-oxofriedelan-26-oic acid), trichadenal (3β-hydroxyfriedelan-26-al), and O-acetyl-trichadenal have been isolated, correlated, and identified. The extracts also contained friedelan-3α-yl acetate and β-sitosterol.

Chemical investigation of ceylonese plants. Part XVII. Isolation and structures of the xanthones in the extractives of Mesua ferrea L. (form M. salicina Pl. and Tr.)(Guttiferae)

From the timber extractives of Mesua ferrea L. (form M. salicina Pl. and Tr.) nine known xanthones (2-hydroxy-, 2-methoxy-, 4-hydroxy-, 1,5-dihydroxy-, 1,7-dihydroxy-, 1-hydroxy-5-methoxy-, 1-hydroxy-7-methoxy, 3-hydroxy-4-methoxy-, and 1,5,6-trihydroxy-) and two new xanthones (1,3,6-trihydroxy-7,8-dimethoxy- and 3,6-dihydroxy-1,7,8-trimethoxy-) have been isolated and characterised. Taxonomic and biogenetic correlations are discussed.

Chemical investigation of ceylonese plants. Part 21. Extractives of Pentadesma butyracea Sabine (Guttiferae)

From the bark and timber extracts of Pentadesma butyracea Sabine the following compounds have been isolated: β-amyrin acetate, β-amyrin, β-sitosterol, 1,3,5-trihydroxy-2-methoxyxanthone, jacareubin, osajaxanthone, and a new xanthone, pentadesmaxanthone, identified as 5,9,11-trihydroxy-3,3-dimethyl-6,8-bis-(3-methylbut-2-enyl)-3H,12H-pyrano[3,2-a]xanthen-12-one.