Iridoids from the roots of Triosteum pinnatifidum

A chemical investigation of the roots of Triosteum pinnatifidum led to the isolation of 10 iridoids, elucidated as triohimas A–C, naucledal, secologanin dimethyl acetal, grandifloroside, sweroside, loganin, vogeloside and (E)-aldosecologanin. Most of the compounds were derived from loganin or secologanin with a glucose moiety at C-1 position. The results indicate a close relationship between the two genera Triosteum and Lonicera, and support the viewpoint that the iridoids derived from loganin or secologanin could be the chemotaxonomic markers of the Caprifoliaceae family.     

Cytotoxic triterpenes from the aerial roots of Ficus microcarpa

Six triterpenes, 3beta-acetoxy-12,19-dioxo-13(18)-oleanene (1), 3beta-acetoxy-19(29)-taraxasten-20alpha-ol (2), 3beta-acetoxy-21alpha,22alpha-epoxytaraxastan-20alpha-ol (3), 3,22-dioxo-20-taraxastene (4), 3beta-acetoxy-11alpha,12alpha-epoxy-16-oxo-14-taraxerene (5), 3beta-acetoxy-25-methoxylanosta-8,23-diene (6) along with nine known triterpenes, 3beta-acetoxy-11alpha,12alpha-epoxy-14-taraxerene (7), 3beta-acetoxy-25-hydroxylanosta-8,23-diene (8), oleanonic acid (9), acetylbetulinic acid (10), betulonic acid (11), acetylursolic acid (12), ursonic acid (13), ursolic acid (14), and 3-oxofriedelan-28-oic acid (15) were isolated from the aerial roots of Ficus microcarpa, and their structures elucidated by spectroscopic methods. The in vitro cytotoxic efficacy of these triterpenes was investigated using three human cancer cell lines, namely, HONE-1 nasopharyngeal carcinoma, KB oral epidermoid carcinoma, and HT29 colorectal carcinoma cells. Compound 8 and pentacyclic triterpenes 9-15 possessing a carboxylic acid functionality at C-28 showed significant cytotoxic activities against the aforementioned cell lines and gave IC50 values in the range 4.0-9.4 microM.     

Fabacyl acetate, a germination stimulant for root parasitic plants from Pisum sativum

A germination stimulant, fabacyl acetate, was purified from root exudates of pea (Pisum sativum L.) and its structure was determined as ent-2′-epi-4a,8a-epoxyorobanchyl acetate [(3aR,4R,4aR,8bS,E)-4a,8a-epoxy-8,8-dimethyl-3-(((R)-4-methyl-5-oxo-2,5-dihydrofuran-2-yloxy)methylene)-2-oxo-3,3a,4,5,6,7,8,8b-decahydro-2H-indeno[1,2-b]furan-4-yl acetate], by 1D and 2D NMR spectroscopic, ESI- and EI-MS spectrometric, X-ray crystallographic analyses, and by comparing the ¹H NMR spectroscopic data and relative retention times (RR_t) in LC-MS and GC-MS with those of synthetic standards prepared from (+)-orobanchol and (+)-2′-epiorobanchol. The ¹H NMR spectroscopic data and RR_t of fabacyl acetate were identical with those of an isomer prepared from (+)-2′-epiorobanchol except for the opposite sign in CD spectra. This is the first natural ent-strigolactone containing an epoxide group. Fabacyl acetate was previously detected in root exudates of other Fabaceae plants including faba bean (Vicia faba L.) and alfalfa (Medicago sativa L.).     

Environmental factors regulating the radial oxygen loss from roots of Myriophyllum spicatum and Potamogeton crispus

Myriophyllum spicatum and Potamogeton crispus are common species of shallow eutrophic lakes in north-eastern Germany, where a slow recovery of the submersed aquatic vegetation was observed. Thus, the characterisation of the root oxygen release (ROL) as well as its implication for geochemical processes in the sediment are of particular interest. A combination of microelectrode measurements, methylene blue agar and a titanium(III) redox buffer was used to investigate the influence of the oxygen content in the water column on ROL, diel ROL dynamics as well as the impact of sediment milieu. Oxygen gradients around the roots revealed a maximum oxygen diffusion zone of up to 250 μm. During a sequence with a light/dark cycle as well as alternating aeration of the water column, maximum ROL with up to 35% oxygen saturation at the root surface occurred under light/O₂-saturated conditions. A decrease to about 30% was observed under dark/O₂-saturated conditions, no ROL was detected at dark/O₂-depleted conditions and only a weak ROL with 5–10% oxygen saturation at the root surface was measured under light but O₂-depleted water column. These results indicate, that during darkness, ROL is supplied by oxygen from the water column and even during illumination and active photosynthesis production, ROL is modified by the oxygen content in the water column. Visualisation of ROL patterns revealed an enhanced ROL for plants which were grown in sulfidic littoral sediment in comparison to plants grown in pure quartz sand. For both plant species grown in sulfidic littoral sediment, a ROL rate of 3–4 μmol O₂ h⁻¹ plant⁻¹ was determined with the Ti(III) redox buffer. For plants grown in pure quartz sand, the ROL rate decreased to 1–2 μmol O₂ h⁻¹ plant⁻¹. Hence, aside from the oxygen content in the water column, the redox conditions and microbial oxygen demand in the sediment has to be considered as a further major determinant of ROL.     

Distribution of exudate flavonoids in the genus Plectranthus

Thirty-four species of the genus Plectranthus (including species of the former genera Coleus and Solenostemon, fam. Lamiaceae) were surveyed for exudate flavonoids to see whether the distribution of these compounds would support a recent classification of the genus based on molecular and morphological characters. In this classification two major groups had been identified, the Coleus and Plectranthus clades. Only about 40% of the species, predominantly from the Plectranthus clade, were found to produce exudate flavonoids, which were mainly flavones. Flavanones were restricted to five species of the Plectranthus clade, whereas flavonols were only found in two species of the Coleus clade, Plectranthus montanus Benth. (synonyms Plectranthus marrubioides Hochst. ex Benth. and Plectranthus cylindraceus Hochst. ex Benth.) and Plectranthus pseudomarrubioides R.H.Willemse. Four of these flavonols were isolated from P. montanus and identified by NMR spectroscopy as the 3,7-dimethyl ether and 3,7,4′-trimethyl ether of quercetin and the 3,6,7-trimethyl ether and 3,6,7,4′-tetramethyl ether of quercetagetin. The remaining flavonols and flavones were identified by HPLC–UV and LC–MS of crude extracts on the basis of their UV and mass spectra, retention times and comparison with standards. Most flavonols were 3-methyl ethers and many of the flavones and flavonols were oxygenated at the 6-position. The most common flavones, occurring in both clades, were cirsimaritin and salvigenin, which are methoxylated at the 6- and 7-positions. 6-Hydroxylated flavones such as scutellarein and ladanein were restricted to species of the Plectranthus clade.     

Phylogenetically distinct Wolbachia gene and pseudogene sequences obtained from the African onchocerciasis vector Simulium squamosum

Wolbachia are intracellular bacteria mostly found in a diverse range of arthropods and filarial nematodes. They have been classified into seven distinct ‘supergroups’ and other lineages on the basis of molecular phylogenetics. The arthropod-infecting Wolbachia are usually regarded as reproductive parasites because they manipulate their host species’ sexing system to enhance their own spread, and this has led to their investigation as potential agents of genetic control in medical entomology. We report 12 partial Wolbachia gene sequences from: aspC, aspS, dnaA, fbpA, ftsZ, GroEL, hcpA, IDA, rpoB, rpe, TopI and wsp as well as a single ftsZ pseudogene sequence, which have all been PCR-amplified from Simulium squamosum (Diptera: Simuliidae). To our knowledge this is the first such report from Simuliidae. Uninterrupted open-reading frame sequences were obtained from all 12 genes, covering ∼6.2 kb of unique DNA sequence. Phylogenetic analyses with the different coding genes gave consistent results suggesting that the Wolbachia sequences obtained here do not derive from any of the known Wolbachia supergroups or lineages. Consistent with a unique genetic status for the S. squamosumWolbachia, the hypervariable regions of the Wolbachia-specific wsp gene were distinct from all previous records in both sequence and length. As well as potential implications for newly emerging Wolbachia-based disease control methods, the results may be relevant to some problems experienced in the laboratory colonisation of Simulium damnosum sensu lato and why it is such a diverse species complex.     

Septal pore complex morphology in the Agaricomycotina (Basidiomycota) with emphasis on the Cantharellales and Hymenochaetales

The ultrastructure of septa and septum-associated septal pore caps are important taxonomic markers in the Agaricomycotina (Basidiomycota, Fungi). The septal pore caps covering the typical basidiomycetous dolipore septum are divided into three main phenotypically recognized morphotypes: vesicular-tubular (including the vesicular, sacculate, tubular, ampulliform, and globular morphotypes), imperforate, and perforate. Until recently, the septal pore cap-type reflected the higher-order relationships within the Agaricomycotina. However, the new classification of Fungi resulted in many changes including revision of existing and addition of new orders. Therefore, the septal pore cap ultrastructure of more than 325 species as reported in literature was related to this new classification. In addition, the septal pore cap ultrastructures of Rickenella fibula and Cantharellus formosus were examined by transmission electron microscopy. Both fungi have dolipore septa associated with perforate septal pore caps. These results combined with data from the literature show that the septal pore cap-type within orders of the Agaricomycotina is generally monomorphic, except for the Cantharellales and Hymenochaetales.It appears from the fungal phylogeny combined with the septal pore cap ultrastructure that the vesicular-tubular and the imperforate type both may have arisen from endoplasmic reticulum. Thereafter, the imperforate type eventually gave rise to the perforate septal pore cap-type.     

A molecular analysis of some Eastern Atlantic grouper from the Epinephelus and Mycteroperca genus

Mitochondrial cytochrome b (397 bp) and 16S rDNA (516 bp) sequences analysis was used to investigate the phylogenetic relationships among some Eastern Atlantic Epinephelinae species. Six species of Epinephelus (E. aeneus, E. caninus, E. costae, E. haifensis, E. marginatus and E. tauvina) and two species of Mycteroperca (M. rubra and M. fusca) were analysed. Neighbour-joining and maximum-parsimony analysis support the paraphyletic grouping of the Epinephelus and Mycteroperca analysed. The maximum pairwise nucleotide divergence value in cyt b among all taxa was 0.196 between E. aeneus and E. marginatus and the minimum value was 0.006 between E. costae and M. rubra. Meanwhile, in 16S sequence analysis, the maximum value is 0.093 between E. aeneus and E. tauvina and the minimum value is 0.011 between E. marginatus and M. rubra. Molecular clock estimates for the species suggest a divergence time of 20-24 mya, which coincides with the Miocene period. A molecular analysis was also conducted, using other Epinephelinae sequences from GenBank in order to improve our understanding of the phyletic status of the Epinephelus and Mycteroperca species analysed.