Antitumor-Promoting Effects of New Sesquiterpenes fromCrossopetalum tonduzii

Abstract

Seven new sesquiterpenes (1-7) with a 'dihydro-beta-agarofuran' (= 5,11-epoxy-5beta,10alpha-eudesmane) skeleton were isolated from Crossopetalum tonduzii. Their structures were elucidated spectroscopically, especially by means of homo- and heteronuclear NMR correlation (COSY, ROESY, HSQC, and HMBC). The absolute configurations of the new compounds were determined by circular dichroism (CD) studies and by chemical correlations via the derivatives 8-11. The new compounds showed moderate antitumor-promoting effects with respect to the activation of the Epstein-Barr virus early antigen (EBV-EA).

The dihydro-β-agarofuran sesquiterpenoids

“…A general methodology for elucidating the regiosubstitution patterns of the ester functions regioisomeric and stereoisomeric structures of these sesquiterpene derivatives has been established. 97,122,145,146,150,170,176,183,185,225,231 The methodology applies a detailed comparison of 1 H and 13 C NMR spectroscopic studies, including 1 H- 13 C heteronuclear correlation (HMQC, HSQC and HMBC) and 1 H-1 H homonuclear correlation (COSY, NOESY and ROESY) experiments and interpretation of exciton couplings in circular dichroism (CD) spectra. Hydrolysis and preparation of derivatives provide additional information.…”

“…185 Furthermore, although all 10 compounds have the same 8-epi-4a-hydroxyalatol skeleton, 328, 327 and 326 were more potent inhibitors than others, suggesting niconitic residues in 312-318 reduced the inhibitory activity. 183,185 Sesquiterpene alkaloids isolated from the root barks of Tripterygium hypoglaucum induced apoptosis of HL-60 (human promyelocytic leukemia) cells through c-myc and nuclear factor jB (NF-jB) signalling pathways. 260 The stems and leaves of Maytenus emarginata produced nine evoninate-type sesquiterpene alkaloids with a-pyridone at C-2.…”

Natural sesquiterpenoids

“…245 The total synthesis of two 4,5-dioxo-seco-eudesmane sesquiterpenes has been described. 246,247 Several dihydroagarofuran derivatives have been isolated from Celastrus orbiculatus, 248, 249 Crossopetalum tonduzii, 250 Tripterygium wilfordii 251 and Zinowiewia costaricensis. 252 Six compounds of the last species were shown to reverse the multidrug resistance phenotype mediated by P-glycoprotein in tumour cells, whilst other compounds of this type displayed the same effects in the protozoan parasite Leishmania.…”

Structure Elucidation and Characterization of Microbial 2-Tridecyl Sophorosides (Biosurfactants)

“…Recently, glycoglycerolipid analogues bearing short-to medium-length lipophilic chains, have shown antitumour-promoting activity in the TPApromoted in vitro Epstein-Barr virus early antigen (EBV-EA) activation test (Colombo et al, , 2005(Colombo et al, , 2006. Also some other compounds from natural sources, such as coumarins, sesquiterpenes or triterpenoids, may be valuable as antitumour promoters in chemical carcinogenesis (Fukuda et al, 2005;Ito et al, 2005;Mendoza et al, 2005). The mechanisms by which such compounds interfere with tumour promotion need yet to be identifi ed.…”