Pedja Janaćković

Guaianolides from Centaurea nicolai: antifungal activity

A new guaianolide, 3-deacetyl-9-O-acetylsalograviolide A, along with four known closely related lactones, salograviolide A, 9-O-acetylsalograviolide A, kandavanolide and salograviolide B were detected in the aerial parts of the flowering plant Centaurea nicolai. Antifungal tests performed on salograviolide A and its 9-O-acetyl and 3-O-deacetyl-9-O-acetyl derivatives revealed inhibitory activity against Aspergillus niger, A. ochraceus, Penicillium ochrochloron, Cladosporium cladosporoides, Fusarium tricinctum and Phomopsis helianthi. Neither of them was active against Trichoderma viride.

Sesquiterpene lactones from Cicerbita alpina

1. Subject and sourceThe roots of Cicerbita alpina (L.) Wallr. were collected from Mt. Komovi, Mon-tenegro. Voucher specimen accession number CAS0799 is deposited in the herbariumat the Faculty of Biology, University of Belgrade—Herbarium Code BEOU.2. Previous workPrevious investigations of the aerial parts of alpine chicory Cicerbita alpina haveshown the presence of insect anti-feedant compounds (Bloszyk, 1988, 1989) and aninsulin-like principle (Schwabe, 1973a, b). From the ethanol extract of the roots, thefuranocoumarins: imperatorin, isoimperatorin, oxypeucedanin and ostruthol and thesesquiterpene lactones: 8-acetyl-15-β-d-glucopyranosyllactucin (1) and 11β,13-dihy-drolactucin (2) were reported by Appendino et al. (1991).

Biogeographic Variation of Foliar n-Alkanes of Juniperus communis var. saxatilis Pallas from the Balkans

The composition of the epicuticular n‐alkanes isolated from the leaves of ten populations of Juniperus communis L. var. saxatilis Pallas from central (continental) and western (coastal) areas of the Balkan Peninsula was characterized by GC‐FID and GC/MS analyses. In the leaf waxes, 14 n‐alkane homologues with chain‐lengths ranging from C22 to C35 were identified. All samples were dominated by n‐tritriacontane (C33), but differences in two other dominant n‐alkanes allowed separating the coastal from the continental populations. Several statistical methods (ANOVA, principal component, discriminant, and cluster analyses as well as the Mantel test) were deployed to analyze the diversity and variability of the epicuticular‐leaf‐n‐alkane patterns of the ten natural populations of J. communis var. saxatilis and their relation to different geographic and bioclimatic parameters. Cluster analysis showed a high correlation of the leaf‐n‐alkane patterns with the geographical distribution of the investigated samples, differentiating the coastal from the continental populations of this taxon. Several bioclimatic parameters related to aridity were highly correlated with this differentiation.

Leaf n-alkanes as characters differentiating coastal and continental Juniperus deltoides populations from the Balkan Peninsula.

The composition of the cuticular n‐alkanes isolated from the leaves of nine populations of Juniperus deltoides R.P.Adams from continental and coastal areas of the Balkan Peninsula was characterized by GC‐FID and GC/MS analyses. In the leaf waxes, 14 n‐alkane homologues with chain‐lengths ranging from C22 to C35 were identified. n‐Tritriacontane (C33) was dominant in the waxes of all populations, but variations between the populations in the contents of all n‐alkanes were observed. Several statistical methods (ANOVA, principal component, discriminant, and cluster analyses) were used to investigate the diversity and variability of the cuticular‐leaf‐n‐alkane patterns of the nine J. deltoides populations. This is the first report on the n‐alkane composition for this species. The multivariate statistical analyses evidenced a high correlation of the leaf‐n‐alkane pattern with the geographical distribution of the investigated samples, differentiating the coastal from the continental populations of this taxon.

Composition of Leaf n-Alkanes in Three Satureja montana L. Subspecies from the Balkan Peninsula: Ecological and Taxonomic Aspects

The composition of the epicuticular leaf n‐alkanes of eight populations of three Satureja montana subspecies (S. montana L. subsp. pisidica (Wettst.) Šilić, S. montana L. subsp. montana, and S. montana L. subsp. variegata (Host) P. W. Ball), from central and western areas of the Balkan Peninsula was characterized by GC‐FID and GC/MS analyses. In the leaf waxes, 15 n‐alkane homologs with chain‐lengths ranging from C21 to C35 were identified. The main n‐alkane in almost all samples was n‐nonacosane (C29), but differences in the contents of three other dominant n‐alkanes allowed separating the coastal from the continental populations. The diversity and variability of the epicuticular‐leaf‐n‐alkane patterns and their relation to different geographic and bioclimatic parameters were analyzed by several statistical methods (principal component, discriminant, and cluster analyses as well as the Mantel test). All tests showed a high correlation between the leaf n‐alkane pattern and the geographical distribution of the investigated populations, confirming the differentiation between S. montana subsp. pisidica and the other two subspecies. The S. montana subsp. variegata and S. montana subsp. montana populations are geographically closer and their differentiation according to the leaf‐n‐alkane patterns was not clear, even though there was some indication of discrimination between them. Moreover, most of the bioclimatic parameters related to temperature were highly correlated with the differentiation of the coastal and the continental populations.

Scanning electron microscopy coupled with energy dispersive spectrometric analysis reveals for the first time weddellite and sylvite crystals on the surface of involucral bracts and petals of two Xeranthemum L. (Compositae) species

In this work, weddellite and sylvite crystals are identified for the first time on the involucral bracts and petals of Xeranthemum annuum and Xeranthemum cylindraceum using scanning electron microscopy coupled with energy dispersive spectrometric (SEM-EDS) analysis. Well-developed crystals of weddellite (CaC2O4·2H2O) occur in the form of a tetragonal bipyramid (hhl), rarely in combination of a bipyramid and tetragonal prism (h00). Indumentum of involucral bracts of X. cylindraceum consists of nonglandular and glandular trichomes. Sylvite (KCl) crystals are observed only on the petal surface of X. cylindraceum. The crystals of sylvite occur in the form of perfect cubes (hexahedrons), but some crystals are deformed, i.e., partially elongated. Taxonomic significance of investigated microcharacters as well as the use of SEM-EDS analysis in taxonomic studies of plants are discussed.

Essential Oil Composition of Centaurea atropurpurea and Centaurea orientalis Inflorescences from the Central Balkans - Ecological Significance and Taxonomic Implications.

The essential oil composition of Centaurea atropurpurea and Centaurea orientalis flowering heads (capitula) from Central Balkans have been determined by GC‐FID and GC/MS analyses. In total, 121 compounds were identified, representing on average 97.7% of the oil composition. In all samples, sesquiterpenes were most abundant group, representing 53.9 – 74.0% of the total oil. Sesquiterpene hydrocarbons dominated in all studied populations of C. orientalis and C. atropurpurea, except C. atropurpurea f. flava in which essential oil was characterized with high level of oxygenated sesquiterpenes. The dominant components differed between species, and also between typical C. atropurpurea and C. atropurpurea f. flava. The most abundant compounds of essential oil of C. orientalis were germacrene D and α‐cadinol. In C. atropuruprea, germacrene D and β‐caryophyllene were the most abundant, while caryophyllene oxide and β‐caryophyllene were dominant in C. atropurpurea f. flava oil. Taxonomical and ecological implications are further discussed.