Epikatonic acid from Austroplenckia populnea: structure elucidation by 2D NMR spectroscopy and X‐ray crystallography

Abstract

From the chloroform extract of Austroplenckia populnea, epikatonic acid, friedelin, populnonic acid, abruslactone A, salaspermic acid and 22b-epi-maytenfolic acid were isolated. The structure and stereochemistry of epikatonic acid were established by two-dimensional NMR spectroscopic techniques (HMQC, HMBC and NOESY) and later confirmed by single crystal X-ray diffraction as 3b-hydroxyolean-12-en-29-oic acid, which unambiguously established the configuration of the hydroxyl group at C-3 as 3b-OH and the carboxyl group at C-20 as 20a-COOH. The crystal structure shows two independent molecules in the asymmetric unit. The crystal packing is stabilized by four O-H· · ·O intermolecular hydrogen bonds, which give rise to infinite double chains along the c axis.

Evaluation of antibacterial activity of "Mangabarana" Austroplenckia populnea Reissek (Celastraceae)

“…The PCTTs (4), (6) and(8) were esterified to obtain methyl populnonate (5), methyl katotonate (7) and methyl epikatonate (9), respectivaly. Infrared (IR), mass spectrometry (MS) and nuclear magnetic resonance ( 1 H and 13 C NMR including 2D experiments) were used to elucidate the chemical structure of the compounds (Souza et al, 1990;Vieira Filho et al, 1999;Vieira Filho et al, 2000;Vieira Filho et al, 2001;Cotta et al, 1990;Silva et al, 2002;Zanon et al, 2008).…”

“…1988;Souza et al, 1990;Silva et al, 2002;Vieira Filho et al, 1999;Vieira Filho et al, 2000;Vieira Filho et al, 2001;Cotta et al, 1990 a, b).…”

Four Brazilian Maytenus salicifolia Reissek (Celastraceae) groups studied by TLC and UV/Vis spectrophotometry

“…The chromatoplate spots (R f ) ( Figure 4 and 5) were obtained with spray of vanillin/perchloric acid solution, as suggested by Wagner (1996). Friedelin, 3β-friedelanol, 3α-friedelanol, α-amyrin, β-amyrin and 3β-sitosterol previously isolated from Maytenus species and chemically identified by spectrometric techniques (Silva et al, 2002;Miranda et al, 2006) Four Brazilian Maytenus salicifolia Reissek (Celastraceae) groups studied by TLC and UV/Vis spectrophotometry…”

Influence of hydrogen bonds on the molecular structure and conformations of two (C30H48O2) pentacyclic triterpene isomers

“…As part of our ongoing search for new biologically active compounds [6][7][8][9][10][11][12][13][14] from plants, we have investigated Maytenus imbricata (Celastraceae), a plant native in the savana region of Minas Gerais and Bahia states in Brazil. Three PCTTs named as 30-hydroxy-lup-20(29)-en-3-one (1) and (11α)-11-hydroxy-lup-20(29)-en-3-one (2), and 3β,30-dihydroxylup-20(29)-ene (3) [2] have previously been isolated from M. imbricata.…”

“…For all PCTTs studied by single crystal X-ray diffraction cited above, the molecular structure and, in some cases, the relative stereochemistry have also been established by a detailed NMR spectral data analysis [2,[10][11][12][13]. Due to the importance of weak intermolecular interactions on the macroscopic properties of solids such as solubility, chemical stability, melting point, density, etc., in addition to their intramolecular geometry, it is important to know the crystal packing forces or intermolecular bonding motifs such as hydrogen bonds, aromatic π-π stacking, steric repulsion, and van der Waals forces.…”