Complete NMR Assignments of the Antibacterial Biflavonoid GB1 from Garcinia kola

Abstract

From the antibacterial fraction of the roots of Garcinia kola, 3؆,4,4ٟ,5,5؆,7,7؆-heptahydroxy-3,8؆-biflavanone (GB1) was isolated as the major constituent, whose interesting conformations were studied on the basis of its 1D and 2D NMR spectra obtained at different temperatures and in different solvents. GB1 showed antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) with MIC of 32 and 128 m mg/ml, respectively.

Two New Xanthones Isolated from the Stem Bark of Garcinia lancilimba

“…The CHCl 3 fraction of the stem bark of G. lancilimba were subjected to repeated column chromatography to yield two new prenylated xanthones (1 and 2) together with 6 known compounds (3)(4)(5)(6)(7)(8) (Fig. 2) C and DEPT NMR spectra displayed the signals of 23 carbons including 13 quaternary carbons, 5 methine carbons, one methylene carbon, and four methyl carbons, which could be well assigned to a diprenylated xanthone skeleton.…”

“…5,6) Recent reports from our lab have focused on the cytotoxicities, 7) stability, 8) and quantitative analysis 9) of the prenylated xanthones of G. hanburyi whose major component, gambogic acid, has been developed as an anticancer drug in China. We also reported the separation and identification of several new polyprenylated xanthones, especially the C-2 epimers of gambogic acid and its analogues.…”

Ocorrência de biflavonoides em Clusiaceae: aspectos químicos e farmacológicos

“…O biflavonoide GB1 (Garcinia Biflavonoid) é um dos principais constituintes de G. kola, uma das espécies mais estudadas do ponto de vista farmacológico do gênero Garcinia. 15 Os biflavonoides do tipo GB-1a, também denominados I-3,II-8-binaringenina, 16 foram isolados em cerca de 20 espécies de Clusiaceae (Tabela 1). A morelloflavona consiste no primeiro biflavonoide conhecido do tipo flavanona-(3→8")-flavona e foi isolada a partir das sementes de G. morella em 1967.…”

“…17 Este tipo de compostos, incluindo GB1 e GB1a, apresenta complexidade espectral à temperatura ambiente, devido à barreira rotacional em torno da ligação (C3→C8") entre as unidades flavanona e flavona, resultando na formação uma mistura de atropoisômeros. 15,17 Às vezes, as análises por RMN 1 H permitem perceber a existência de confôrmeros nesses dímeros, como o caso da agathisflavona (C6→C8") cujo espectro do derivado acetilado apresenta deformações nos sinais de alguns núcleos da molécula. 18 Por último, os biflavonoides do tipo amentoflavona, que possuem ligação interflavonoide do tipo (C3'→C8"), são diferentes dos demais tipos citados, sendo igualmente abundantes dentro da família Clusiaceae.…”

Qualitative and quantitative analysis of polycyclic polyprenylated acylphloroglucinols from Garcinia species using ultra performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

“…Other members of PPAPs like guttiferones A-E, xanthochymol and their analogues exhibit antibiotic, anti-HIV and cytotoxic activities [12][13][14]. In our laboratory, the continuous investigation on Garcinia species, including Garcinia xipshuanbannaensis [15], Garcinia kola [16], Garcinia lancilimba [17], Garcinia xanthochymus [18], Garcinia yunnanensis [19], Garcinia oblongifolia [20] and Garcinia hanburyi [21][22][23][24] has led to a series of reports on xanthones and PPAPs derivatives and their anticancer activities. For example, olblongifolin C isolated from G. yunnanensis has shown growth inhibitory effects against HeLa cells expressing a caspase sensor protein [19].…”