Furanocoumarins from Dorsteniafoetida

The linear furanocoumarins 5-(2,3-epoxy-3-methyl-butoxy)-chalepensin, 5-methoxy-3-(3-methyl-2,3-dihydroxybutyl)-psoralen-diacetate (7), 5-methoxy-3-[3-(β-d-glucopyranosyloxy)-2-acetyloxy-3-methyl-butyl]-psoralen and 5-(3-methyl-2,3-dihydroxybutyloxy)-3-[3-(β-d-glucopyranosyloxy)-2-hydroxy-3-methyl-butyl]-psoralen, and the coumarin derivative 7-hydroxy-5-methoxy-6-carboxymethyl-3-[3-(β-d-glucopyranosyloxy)-2-hydroxy-3-methyl-butyl]-coumarin were isolated from the leaves of Dorstenia foetida (Moraceae) along with the known compounds psoralen, bergapten, isopimpinellin, phellopterin, 5-methoxychalepensin and turbinatocoumarin. Further furanocoumarins were characterized by ESI-MS/MS investigations. The nonpolar extracts of D. foetida exhibit antifungal, antibacterial and cytotoxic activity, however, no anthelminthic activity.     

Cassane Diterpenes from Caesalpinia bonduc

Three cassane diterpene hemiketals, caesalpinolide-C, caesalpinolide-D, caesalpinolide-E and one cassane furanoditerpene were isolated from Caesalpinia bonduc. The molecular structures were elucidated using NMR spectroscopy in combination with IR, UV and mass spectral data and relative stereochemistries were determined through ROESY correlation. The isolated compounds were tested for their antiproliferative activity against MCF-7 (breast adenocarcinoma), DU145 (prostate carcinoma), C33A (Cervical carcinoma) and Vero (African green monkey kidney fibroblast) cells.     

Incidence of Venturia shoot blight in aspen (Populus tremuloides Michx.) varies with tree chemistry and genotype

Quaking aspen (Populus tremuloides) is a foundation tree species in North American forests, as well as a valuable source of wood and paper products. Quaking aspen exhibits substantial genetic variation within and among natural populations in phytochemical compounds that influence both interactions with herbivores and ecosystem dynamics. The potential association of these phytochemicals with disease resistance, however, is unknown. Here we present the results of a “natural experiment” in a common garden of quaking aspen genotypes infected with shoot blight (Venturia moreletii). We found that the incidence of shoot blight varied by 10-fold among aspen genotypes, and was strongly and negatively correlated with constitutive foliar concentrations of condensed tannins. Selection factors that shape the genetic and phytochemical architecture of aspen populations may thus simultaneously influence aspen resistance to pathogen attack, with consequences for individual tree fitness as well as community organization, via “extended phenotype” effects.     

Morphological,Secondary Metabolite and ITS (rDNA) Variability within Usnic Acid‐Containing Lichen Thalli of Xanthoparmelia Explored at the Local Scale of Rock Outcrop in W‐Alps

Lichen secondary metabolites (LSMs) are regarded with interest for valuable biological properties, but chemical variability among/within lichen taxa has been only fragmentarily characterized by advanced analytical techniques. Knowledge of variability at a local geographic scale has been particularly neglected, while it should address the collection of chemically homogeneous materials to test and exploit LSMs. Here we evaluated the chemical variability of 48 Xanthoparmelia specimens from two rock outcrops in Western Italian Alps, representative of nine morphotypes and sixteen rDNA ITS haplotypes. Qualitative and quantitative analyses were performed by HPLC‐DAD‐ESI‐MS₂ and UPLC‐HDR‐DAD, respectively, and revealed the occurrence of 18 LSMs. Chemical partition allowed distinguishing six chemical groups, only partially overlapping with distinct morphotypes and three divergent haplotype groups, which, overall, accounted for the co‐occurrence of different taxa only in part identifiable with species described for Europe. Some morphotypes were variable in presence and concentration of LSMs, and chemical divergences also characterized single ITS haplotypes. Accordingly, the collection of chemically homogeneous materials, even at a local scale, may be not properly addressed by morphological features and ITS barcoding, and should be confirmed by a specimen‐level chemical characterization.     

Agarofuran sesquiterpenes from Schaefferia argentinensis

Sixteen dihydro-β-agarofuran sesquiterpenes were isolated from the aerial parts of Schaefferia argentinensis Speg. Their structures were determined by a combination of 1D and 2D NMR and MS techniques. The in vitro antiproliferative activity of the major sesquiterpenes was examined in T47D, MCF7, and MDA-MB231 human cancer cell lines, but was found to be marginal.     

CO2 and light effects on deciduous trees: growth, foliar chemistry, and insect performance

This study examined the effects of CO₂ and light availability on sapling growth and foliar chemistry, and consequences for insect performance. Quaking aspen (Populus tremuloides Michx.), paper birch (Betula papyrifera Marsh.), and sugar maple (Acer saccharum Marsh.) were grown in controlled environment greenhouses under ambient or elevated CO₂ (38.7 and 69.6 Pa), and low or high light availability (375 and 855 μmol m⁻² s⁻¹). Because CO₂ and light are both required for carbon assimilation, the levels of these two resources are expected to have strong interactive effects on tree growth and secondary metabolism. Results from this study support that prediction, indicating that the relative effect of rising atmospheric CO₂ concentrations on the growth and secondary metabolism of deciduous trees may be dependent on light environment. Trees in ambient CO₂-low light environments had substantial levels of phytochemicals despite low growth rates; the concept of basal secondary metabolism is proposed to explain allocation to secondary metabolites under growth-limiting conditions. Differences between CO₂ and light effects on the responses of growth and secondary metabolite levels suggest that relative allocation is not dependent solely on the amount of carbon assimilated. The relative growth rates and indices of feeding efficiency for gypsy moth (Lymantria dispar L.) larvae fed foliage from the experimental treatments showed no significant interactive effects of light and CO₂, although some main effects and many host species interactions were significant. Gypsy moth performance was negatively correlated with CO₂- and light-induced increases in the phenolic glycoside content of aspen foliage. Insects were not strongly affected, however, by treatment differences in the nutritional and secondary chemical components of birch and maple. Received: 15 July 1998 / Accepted: 23 December 1998