The Role of Through-Bond Stereoelectronic Effects in the Reactivity of 3-Azabicyclo[3.3.1]nonanes

Hyperconjugation/conjugation through-bond stereoelectronic effects were studied with density functional theory in the context of 3-azabicyclo[3.3.1]nonanes to unravel puzzling differences in reactivity between a vinylogous chloride (4) and a vinylogous ester (5). These compounds─whose structures differ only by one substituent─were found to display strikingly different reactivities in hydrochloric acid by Risch and co-workers ( J. Am. Chem. Soc., 1991, 113, 9411-9412). Computational analyses of substituent effects, noncovalent interactions, natural bond orbitals, isodesmic reactions, and hydration propensities lead to a model for which the role of remote, through-bond stereoelectronic effects is the key to explaining 4 and 5's diverging reactivity.

Anti-Helicobacter pylori activity of quinolone alkaloids from Evodiae fructus

A biologically monitored fractionation of methanol extract of the fruit of Evodia rutaecarpa led to the isolation of six quinolone alkaloids, evocarpine (1), 1-methyl-2-[(4Z,7Z)-4,7-tridecadienyl]-4(1H)-quinolone (2), 1-methyl-2-[(6Z,9Z)-6,9-pentadecadienyl]-4(1H)-quinolo ne (3), 1-methyl-2-undecyl-4(1H)-quinolone (4), dihydroevocarpine (5), 1-methyl-2-pentadecyl-4(1H)-quinolone (6). They showed potent anti-Helicobacter pylori activity with the minimum inhibitory concentration (MIC) value of 10-20 microg/ml. However, they had no effect on Helicobacter pylori urease activity at the concentration of 300 microg/ml.

Inhibitory activity of monoamine oxidase by coumarins from Peucedanum japonicum

Four coumarins were isolated from chloroform extract of the root of Peucedanum japonicum and identified as praeruptorin A(1), xanthotoxin (2), psoralen (3) and bergapten (4) on the basis of spectroscopic methods. The inhibitory activities of these coumarins on monoamine oxidase prepared by mouse brain were tested. The IC50 values of them were shown to be 27.4 microM (1), 40.7 microM (2), 35.8 microM (3), and 13.8 microM (4), in vitro.