Proteasome-inhibitory and cytotoxic constituents of Garcinia lateriflora: absolute configuration of caged xanthones

Abstract

A new biflavonoid (1), a new xanthone enantiomer (2), five new caged xanthones (3-7), and several known compounds were isolated from the stem bark of Garcinia lateriflora, collected in Indonesia. The structures of the new compounds were determined by analysis of spectroscopic data, and the absolute configuration of the caged xanthones was shown for the first time at carbons 5, 7, 8, 8a, 10a, and 27, by analysis of COSY and NOESY NMR and ECD spectra. The biflavonoids exhibited proteasome inhibitory activity, and the known compound, morelloflavone (8) was found to have the greatest potency (IC 50 = 1.3 μM). The caged xanthones were cytotoxic

Prenylated caged xanthones: Chemistry and biology

“…The caged xanthones showed potent cytotoxicity toward HT-29 cells with the ED 50 values ranging from 0.36-3.2 μM (Ren et al, 2010).…”

“…The absolute configuration at C5 and C7 were determined as 5S and 7R via the ECD spectra which displayed a positive and a negative Cotton effect near 290 and 360 nm, respectively. Based on the NOESY and CD spectroscopic data the absolute configuration of C10a and C27 were deduced as 10aS and 27S (Ren et al, 2010(Ren et al, , 2011b. The CD spectrum of cochinchinoxanthone (114) showed negative and positive Cotton effect at 292 and 353 nm.…”

“…Prenylated caged xanthones isolated from G. bracteata, bractatin (92) Prenylated caged xanthones 108-112 of G. lateriflora showed potent cytotoxicity toward HT-29 cells (human colon cancer cells) with the ED 50 values of 0.36-3.2 μM (Ren et al, 2010). Gaudichaudione H (60) which was found in G. gaudichaudii, G. cantleyana, and G. urophylla showed growthinhibition activity on MCF-7, DU-145 (human prostate cancer) and NCI-H460 (human lung cancer cells) with the ED 50 values of 6.6-7.6 μM (Khalid et al, 2007).…”

Spectroscopic characterizations, X-ray studies, and electronic circular dichroism calculations of two alkaloid triterpenoids

“…Electronic circular dichroism (ECD) is a useful measurement to determine the absolute configuration of chiral molecules, especially in natural products when combined with theoretical calculations of ECD properties using density functional theory (DFT) [19][20][21]. In order to establish the absolute configuration of 1 and 2, a molecular modeling approach was used.…”

“…Theoretical calculation of the ECD spectrum of compounds 1 and 2 based on the crystal structure was performed showing the p-p interactions, Cg stands for the centroid of the ring Fig. 7 The superposition of the two molecules in the asymmetric unit using time-dependent density functional theory (TDDFT) [19][20][21] with the 6-31G?? (d,p) basis set by the Gaussian 09 program package.…”