Das folhas de Terminalia glabrescens foram obtidos um novo triterpeno pentacíclico (3β,6β,23,28-tetraidroxiolean-12-eno), além dos ácidos ursólico, 2α-hidroxiursólico, oleanólico, maslínico, arjunólico, sumaresinólico e asiático, esqualeno, fitol, sitosterol-3-O-β-D-glucopiranosídeo e nalcanos. Da casca do caule foram obtidos friedelina, taraxerol, lupeol, lupenona, betulina, betulona, ácido betulínico, arjunglucosídeo I, estigmastano-3β,6α-diol, β-sitosterol, (-) catequina, β-Dpiranotagatose, β-D-furanofrutose e α-D-furanofrutose.A new oleanane-type triterpene (3β,6β,23,28-tetrahydroxyolean-12-ene) was isolated from the leaves of Terminalia glabrescens, together with ursolic, 2α-hydroxyursolic, oleanolic, maslinic, arjunolic, sumaresinolic and asiatic acids, squalene, phytol, sitosterol-3-O-β-D-glucopyranoside and n-alkanes. Friedelin, taraxerol, lupeol, lupenone, betulin, betulone, betulinic acid, arjunglucoside I, stigmastane-3β,6α-diol, β-sitosterol, (-) catechin, β-D-pyranotagatose, β-D-furanofructose and α-D-furanofructose were obtained from the trunk bark. Combretaceae, triterpenes, 3β,6β,23,
Keywords: Terminalia glabrescens,
IntroductionPlants of the genus Terminalia (Combretaceae) are known as a rich source of secondary metabolites, such as pentacyclic triterpenes and their glycoside derivatives, flavonoids, tannins and other aromatic compounds, some of which with antibacterial, antifungal, anticancer and hepatoprotective activities.
1-8Terminalia glabrescens Mart., which has not previously been chemically investigated, is a medium-sized tree widespread in Mato Grosso do Sul, Brazil. In the present paper, we describe the isolation and structural elucidation of a new oleanane-type triterpene (3β,6β,23,28-tetrahydroxyolean-12-ene) from the leaves of this species. The known pentacyclic triterpenes ursolic, 2α-hydroxyursolic, oleanolic, maslinic, arjunolic, sumaresinolic and asiatic acids together with squalene, phytol, sitosterol-3-O-β-Dglucopyranoside and foliar wax hydrocarbons were also obtained from the leaves, while the trunk bark afforded the triterpenes friedelin, taraxerol, lupeol, lupenone, betulin, betulone, betulinic acid and arjunglucoside I in addition to stigmastane-3β,6α-diol, β-sitosterol, (-) catechin, β-D-pyranotagatose, β-D-furanofructose and α-D-furanofructose.The structures of the known and new compounds were established on the basis of spectral data, mainly 1 H and 13 C (1D and 2D) NMR spectra and by comparison with authentic samples.
Results and DiscussionThe hexane and CHCl 3 solubles obtained from partition of the ethanol extract of leaves were subjected to a series of normal and reversed phase silica gel column chromatography, gel filtration and preparative TLC on silica gel separations to yield the new pentacyclic triterpene 3β,6β,23,28-tetrahydroxyolean-12-ene (1) in addition to ursolic, 9 oleanolic, 9 2α-hydroxyursolic, 9 maslinic, 9 sumaresinolic (2), 9 asiatic (3) 9 and arjunolic (4) 9 acids, squalene, 10 phytol, sitosterol-3-O-β-D-glucopyranoside and long chain hydrocarbons...