Detail of "6754-13-8"

Reference

Indirect inactivation of rabbit reticulocyte initiation factor eIF-2 by helenalin and bis(helenalinyl) malonate

Indirect inactivation of rabbit reticulocyte initiation factor eIF-2 by helenalin and bis(helenalinyl) malonate. Williams, W. L.; Chaney, Stephen G.; Hall, Iris H.; Lee, Kuo Hsiung (Sch. Med., Univ. North Carolina, Chapel Hill, NC 27514, USA). Biochemistry, 23(23), 5637-44 (English) 1984. CODEN: BICHAW. ISSN: 0006-2960. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) Helenalin (I) [6754-13-8] and bis(helenalinyl) malonate (II) [68322-91-8], sesquiterpene lactones that react primarily with exposed sulfhydryl groups, were equally effective inhibitors of endogenous protein synthesis in rabbit reticulocyte lysates. By use of partially fractionated systems, it was possible to show that I preferentially inhibited the conversion of the ternary initiation complex to the 48S preinitiation complex. II was much less active as an inhibitor of 48S complex formation than I and clearly did not possess sufficient activity in that assay to explain its effectiveness as a protein synthesis inhibitor in whole lysates. Kinetic studies also showed a clear difference between the mechanism of action of these 2 drugs. II inactivated protein synthesis in reticulocyte lysates only after a lag of 10 min, and the inhibition of protein synthesis could be completely reversed by the addn. of 5 mM cAMP. I showed more complex kinetics. Whereas full inhibition only occurred after a lag of 10-15 min, a partial inhibition was obsd. from very early times. CAMP at 5 mM was only partially able to reverse inhibition by I. Phosphorylation studies showed that both I and II were equally effective at activating eIF-2a kinase [82249-72-7] and indirectly causing phosphorylation of eIF-2. Furthermore, both drugs were able to activate eIF-2a kinase at low enough concns. to account for their effectiveness as protein synthesis inhibitors in whole lysates. These data were interpreted to indicate that the activation of eIF-2a kinase was the primary mode of action of II as a protein synthesis inhibitor. I probably acts preferentially at the level of eIF-2a kinase activation in vivo. However, at sufficiently high concns. it also directly inactivates eIF-3.

Effect of selected pseudoguaianolides on survival of the flour beetle, Tribolium confusum

Effect of selected pseudoguaianolides on survival of the flour beetle, Tribolium confusum. Picman, Anna K.; Picman, J. (Chem. Biol. Res. Inst., Agric. Canada, Ottawa, ON K1A 0C6, Can.). Biochem. Syst. Ecol., 12(1), 89-93 (English) 1984. CODEN: BSECBU. ISSN: 0305-1978. DOCUMENT TYPE: Journal CA Section: 5 (Agrochemical Bioregulators) Pseudoguaianolides having an a-methylene-g-lactone moiety, e.g., parthenin (I) [508-59-8], helenalin [6754-13-8], and coronopilin [2571-81-5], were effective against T. confusum at specific concns. (0.2-10%), whereas tenulin [19202-92-7] (0.2-8%) contg. no methylenelactone group had no effect on flour beetle. The a,b-unsatd. ketone moiety had no affect on the activity of these compds. The 3 active compds. had statistically similar effects on the survival of the flour beetle.