Sinnathamby Balasubramaniam

Triterpenoids and coumarins from the leaves of calophyllum cordato-oblongum

Abstract The hot light petrol extractives of the leaves of Calophyllum cordato-oblongum gave D:A-friedo-oleanan-3-one, 28-hydroxy-D:A-friedo-oleanan-3-one (canophyllol) and three new coumarins: cordatolides A and B and oblongulide.

1,2(3)-Tetrahydro-3,3′-biplumbagin: A naphthalenone and other constituents from Plumbago zeylanica☆

Abstract The isolation of plumbagin, droserone, isoshinanolone and a new naphthalenone, 1,2(3)-tetrahydro-3,3′-biplumbagin is reported from the phenolic fract

Two chemically distinct groups of calophyllum species from Sri Lanka

Abstract The leaf extracts of Calophyllum moonii and C. walkeri were investigated. The former contained neoflavonoids whereas the latter had calozeylanic acid. Distribution of natural products in the leaf extracts of seven Calophyllum species has been reviewed and the existence of two chemically distinct groups in Calophyllum species has been recognized.

Terpenoid and biflavonoid constituents of Calophyllum calaba and Garcinia spicata from Sri Lanka

Abstract A new bark acid, isochapelieric acid (cis-chapelieric acid), chapelieric acid, friedelin, friedelan-3β-ol, canophyllal, canophyllol, friedelan-3β,28-diol, canophyllic acid and amentoflavone have been isolated and characterized from leaf extractives of Calophyllum calaba. 13CNMR spectra of methyl chapelierate and methyl isochapelierate have been recorded and interpreted. Leaf extractives of Garcinia spicata afforded an unidentified long chain carboxylic acid, friedelin, friedelan-3β-ol, sitosterol and the biflavanones GB-1, GB-1a, GB-2a and morelloflavone. Chemotaxonomic significance of the occurrence of some of the above foliar constituents in Calophyllum and Garcinia species is discussed.

Polyphenols from dipterocarp species. Vaticaffinol and ε-viniferin

A dipterocarp endemic to Sri Lanka, Vatica affinis, yielded three phenols. Two of them showed anti-bacterial properties and have been shown to be the dimer and tetramer of 3,5,4′-trihydroxystilbene.

Xanthones from roots of three calophyllum species

Abstract The root bark of Calophyllum thwaitesii has been shown to contain two new xanthones: 6,8-dihydroxy-2,2-dimethyl-7(3-methylbut-2-enyl)-2H,5H-pyrano-(3,2-a)xanthen-5-one (calothwaitesixanthone) and 1,3,7-trihydroxy-2,8-di(3-methylbut-2-enyl)xanthone(6-deoxy-γ-mangostin). Thwaitesixanthone has also been isolated from the root bark extracts of C. thwaitesii . The root bark extracts of C. calaba var. calaba and C. bracteatum contained calabaxanthone and calocalabaxanthone. Trapezifolixanthone has also been isolated from C. calaba var. calaba .

Calocalabaxanthone, the putative isoprenyl precursor of calabaxanthone from Calophyllum calaba

Abstract The bark of Calophyllum calaba var. calaba contains a new xanthone, 2,8-di-(3-methylbut-2-enyl)-1,3-dihydroxy-7-methoxyxanthone (calocalabaxanthone), the precursor of 5-hydroxy-8-methoxy-2,2-dimethyl-7-(3-methylbut-2-enyl)-2H,6H-pyano-(3,2-b)-xanthen-6-one (calabaxanthone). In addition the bark contains calabaxthone and the other constituents isolated earlier from Calophyllum calaba var. worthingtonii .

Tirucallane derivatives from Paramignya monophylla fruits

Paramignya monophylla fruits contain flindissone, deoxyfiindissone and four new tirucalladienes, 3-oxotirucalla-7,24-dien-23-ol, 3-oxotirucalla-7,24-diene-21,23-diol and their 3β-hydroxy derivatives.

Gleinene and gleinadiene, 5,7-dimethoxycoumarins from Murraya gleinei root

Abstract Murraya gleinei root contained two new coumarins, 5,7-dimethoxy-8-(3′-methylbutan-1′,3′-dienyl)coumarin (gleinadiene) and 5,7-dimethoxy-8-(3′-methylbut-1′-enyl)coumarin (gleinene), together with eleven other coumarins, stigmasterol, bulnesol, guaiol, α-gurjunene and thirteen other sesquiterpenoids and six fatty acids.

Anti-bacterial activity of extracts from the brown seaweed Stoechospermum marginatum

Abstract The methanol extract of the brown seaweed Stoechospermum marginatum was found to inhibit the growth of Staphylococcus aureus . The active constituents were found to be a mixture of diterpenoid monoacetates having the spatane skeleton.