Skimmiarepin A and B, Two New Insect Growth Inhibitory Triterpenoids from Skimmia japonica Thunb. var. intermedia Komatsu f. repens (Nakai) Hara

Abstract

Two new triterpenoids, skimmiarepin A and B, which both exhibit an insect growth inhibitory activity against the silkworm, Bombyx mori L., have been isolated from the leaves and the fruit of Skimmia japonica Thunb. var. intermedia Komatsu f. repens (Nakai) Hara. Their structures have been determined by extensive 2D NMR studies and chemical methods.

Mitochondrial Respiration Inhibitors Suppress Protein Translation and Hypoxic Signaling via the Hyperphosphorylation and Inactivation of Translation Initiation Factor eIF2α and Elongation Factor eEF2

“…Bioassay-guided isolation and subsequent dereplication-based structure elucidation afforded two known protolimonoids, 1 and 2 . 4,5 In the T47D cell-based reporter assay, 12 both compounds suppressed hypoxia-induced HIF-1 activation with comparable nanomolar IC 50 values (63 nM for 1 , and 68 nM for 2 ; Figures 1A and 1B). The HIF-1 inhibitory effects exerted by 1 and 2 appear to be inducing condition-dependent.…”

“…13 Extensive preclinical and clinical studies support the inhibition of HIF-1 as an important molecular-targeted approach for anticancer drug discovery. 13 Bioassay-guided chromatographic separation of the active A. marmelos extract led to the isolation of two previously identified protolimonoids, skimmiarepin A ( 1 ) 4 and skimmiarepin C ( 2 ). 5 This report describes the identification and characterization of 1 and 2 as potent HIF-1 inhibitors.…”

Structural and 1H and 13C NMR analysis of two new glabretal triterpenoid derivatives from Guarea jamaicensis

“…Doublets at υ 0.34 and υ 0.74 in the 1 H NMR spectrum correlating by HSQC to υ C 16.1 were indicative of a cyclopropyl methylene group; this 13 C shift is typical of C-18 of glabretal triterpenes. 7,8 Structure elucidation proceeded on this indication that the compound was a glabretal derivative. Thus, tentative assignments for the carbon atoms and protons of the pentacyclic triterpene skeleton with acetoxy groups at C-3 and C-7 could be made by comparison with previously reported data for glabretals.…”

“…Thus, tentative assignments for the carbon atoms and protons of the pentacyclic triterpene skeleton with acetoxy groups at C-3 and C-7 could be made by comparison with previously reported data for glabretals. 7,8 The assumed structure was then corroborated and 1 H and 13 C spectra were assigned by 1 H, 1 H COSY, HSQC and HMBC analysis (Table 1), using techniques identical to those that we have used for other triterpenes. 9 For this portion of the molecule there was a great deal of overlap in the 1 H NMR spectrum and this precluded analysis of most of the multiplets; only in a few cases could˛andď esignations be made for protons of methylene pairs on the basis of signal widths.…”

“…1) were obtained from an acetylated fraction of extracts of the leaves and twigs of Guarea jamaicensis, an endemic Jamaican species of rare and restricted occurrence in the hilly limestone regions of the island. 5 The known compounds˛-spinasterol, polyprenol-12 6 and glabretal 1,7 were also isolated. Compound 1 is the first reported tetrahydropyranyl hemiacetal in the glabretal series.…”