Polyprenylated benzoylphloroglucinol-type derivatives including novel cage compounds from Hypericum erectum.

Hyperici erecti herba (Hypericum erectum THUNB.) showed a suppressive effect on generation of isovaleric acid by Corynebacterium xerosis. An ethyl acetate (AcOEt) soluble fraction of methanol extract of H. erectum showed the activity. The AcOEt fraction was separated by various successive choromatographical methods to give seven new compounds 1-7 along with some known compounds. The structures of the new compounds were elucidated to be polyprenylated benzoylphloroglucinol derivatives by means of HR-MS and NMR spectra including 2D-NMR. Some of these compounds had novel cage structures having benzoyltricyclo[3,3,1,1(3,7)]decane and benzoyltricyclo[4,3,1,1(3,8)]undecane skeletons arising from a polyprenylated phloroglucinol precursor by a transannular cyclization reaction. The isolated compounds were tested for suppressive activity, but they showed only weak activity.

Activity of the AIB factor observed in prokaryotic and eukaryotic microorganisms.

Streptomyces cinnamonensis produces a new substance named AIB (for anti-isobutyrate) factor which, on a solid medium, efficiently counteracts toxic concentrations not only of isobutyrate but also of other salts of short-chain monocarboxylic acids. In the present study we demonstrate that the AIB factor activity is widely spread because this effect was positively detected in 25 of 31 randomly chosen microorganisms (streptomycetes, ascomycetes, zygomycetes and basidiomycetes). The AIB factor produced by the tested microorganisms on an agar media allows for germination, growth, and sporulation of the testing Streptomyces coelicolor on an agar medium containing 20 mmol/L acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, and 2-methylbutyrate. The activity of the AIB factor from different sources towards these substances differs.

Induction of the mitochondrial permeability transition in vitro by short-chain carboxylic acids.

We recently reported that acrylic acid (AA) induces the MPT in vitro, which we suggested might be a critical event in the acute inflammatory and hyperplastic response of the olfactory epithelium. The purpose of the present investigation was to determine if induction of the MPT is a general response to short-chain carboxylic acids or if there are critical physical chemical parameters for this response. Freshly isolated rat liver mitochondria were incubated in the presence of varying concentrations of selected carboxylic acids. All of the acids that we tested caused a concentration-dependent induction of the MPT, which was blocked by cyclosporine A. Although the C4 carboxylic acids were slightly more potent than the C5 acids, there was no correlation with the degree of saturation, the octanol/water coefficient (log P), or the dissociation constant (pK(a)) of the acids that we tested. We conclude that induction of the MPT in vitro is a general response to short-chain carboxylic acids having a pK(a) of 4 to 5.