Loganin

About: Loganin is a research topic. Over the lifetime, 340 publications have been published within this topic receiving 5657 citations. The topic is also known as: 1-(beta-D-glucopyranosyloxy)-1,4a,5,6,7,7a-hexahydro-6-hydroxy-7-methylcyclopenta[c]pyran-4-carboxylic acid methyl ester.

Indole alkaloid biosynthesis in Catharanthus roseus: new enzyme activities and identification of cytochrome P450 CYP72A1 as secologanin synthase.

Abstract: Summary The molecular characterization of CYP72A1 from Catharanthus roseus (Madagascar periwinkle) was described nearly a decade ago, but the enzyme function remained unknown. We now show by in situ hybridization and immunohistochemistry that the expression in immature leaves is epidermis-specific. It thus follows the pattern previously established for early enzymes in the pathway to indole alkaloids, suggesting that CYP72A1 may be involved in their biosynthesis. The early reactions in that pathway, i.e. from geraniol to strictosidine, contain several candidates for P450 activities. We investigated in this work two reactions, the conversion of 7-deoxyloganin to loganin (deoxyloganin 7-hydroxylase, DL7H) and the oxidative ring cleavage converting loganin into secologanin (secologanin synthase, SLS). The action of DL7H has not been demonstrated in vitro previously, and SLS has only recently been identified as P450 activity in one other plant. We show for the first time that both enzyme activities are present in microsomes from C. roseus cell cultures. We then tested whether CYP72A1 expressed in E. coli as a translational fusion with the C. roseus P450 reductase (P450Red) has one or both of these activities. The results show that CYP72A1 converts loganin into secologanin.

Response of generalist and specialist insects to qualitative allelochemical variation.

Abstract: We examined the effects of a set of four biosynthetically related iridoid glycosides, aucubin, catalpol, loganin, and asperuloside, on larvae of a generalist,Lymantria dispar (Lymantriidae), the gypsy moth, and an adapted specialist, the buckeye,Junonia coenia (Nymphalidae). In general,L. dispar grew and survived significantly less well on artificial diets containing iridoid glycoside, compared to a control diet without iridoid glycosides. In choice tests, previous exposure to a diet containing iridoid glycosides caused larvae subsequently to prefer iridoid glycoside-containing diets even though they were detrimental to growth and survival. In contrast,J coenia larvae grew and survived better on diets with aucubin and catalpol, the two iridoid glycosides found in the host plantPlantago lanceolata (Plantaginaceae), than on diets with no iridoid glycoside or with loganin and asperuloside. The results of choice tests of diets with and without iridoid glycosides and between diets with different iridoid glycosides reflected these differences as well. These results are discussed in terms of (1) differences between generalists and specialists in their response to qualitative variation in plant allelochemical content, (2) the induction of feeding preferences, and (3) the evolution of qualitative allelochemical variation as a plant defense.

Structural considerations on the iridoids as anti-inflammatory agents.

Abstract: Twelve iridoid glycosides have been evaluated for their anti-inflammatory activity on two models: the carrageenan-induced mouse paw edema and the TPA-induced mouse ear edema. Loganic acid was the most active (44.4% edema inhibition) on the former test, whereas the catalpol derivative mixture isolated from Scrophularia, aucubin, verbenalin, and loganin, showed the highest activity (from 72.0 to 80.0% edema inhibition) on the latter. The results allowed us to establish the relationship between the structure and anti-inflammatory activity on the basis of the different patterns of substitution, particularly hydroxylation, unsaturation, and acylation.