Two new germacranolides from Onopordon leptolepis

The investigation of the aerial parts of O. leptolepis afforded, in addition to a known polyynaldehyde and onopordopicrin, two further germacranolides. The structures are elucidated by spectroscopic methods and by conversion to the corresponding acetates.     

Two new elemanolides from Onopordon leptolepis

The investigation of the polar fractions of the aerial parts of O. leptolepis afforded two new elemanolides, their structures being elucidated by spectroscopic methods and by partial synthesis starting with onopordopicrin.     

Sesquiterpene lactones from Centaurea tweediei

Aerial parts of Centaurea tweediei from Argentina afforded as the main constituent the sesquiterpene lactone onopordopicrin and minor amounts of a new heliangolide, a new guaianolide, a new eudesmanolide, a new eudesmane acid and the lignans arctigenin and matairesinol.     

Onopordopicrin from the new genus Shangwua as a novel thioredoxin reductase inhibitor to induce oxidative stress-mediated tumor cell apoptosis

Isolation and identification of natural products from plants is an essential approach for discovering drug candidates. Herein we report the characterization of three sesquiterpene lactones from a new genus Shangwua, e.g. onopordopicrin (ONP), C2, and C3, and evaluation of their pharmacological functions in interfering cellular redox signaling. Compared to C2 and C3, ONP shows the most potency in killing cancer cells. Further experiments demonstrate that ONP robustly inhibits thioredoxin reductase (TrxR), which leads to perturbation of cellular redox homeostasis with the favor of oxidative stress. Knockdown of the TrxR sensitizes cells to the ONP treatment while overexpression of the enzyme reduces the potency of ONP, underpinning the correlation of TrxR inhibition to the cytotoxicity of ONP. The discovery of ONP expands the library of the natural TrxR inhibitors, and the disclosure of the action mechanism of ONP provides a foundation for the further development of ONP as an anticancer agent.     

Inheritance of Hetero-Diploid Pollen S-Haplotype in Self-Compatible Tetraploid Chinese Cherry (Prunus pseudocerasus Lindl)

The breakdown of self-incompatibility, which could result from the accumulation of non-functional S-haplotypes or competitive interaction between two different functional S-haplotypes, has been studied extensively at the molecular level in tetraploid Rosaceae species. In this study, two tetraploid Chinese cherry (Prunus pseudocerasus) cultivars and one diploid sweet cherry (Prunus avium) cultivar were used to investigate the ploidy of pollen grains and inheritance of pollen-S alleles. Genetic analysis of the S-genotypes of two intercross-pollinated progenies showed that the pollen grains derived from Chinese cherry cultivars were hetero-diploid, and that the two S-haplotypes were made up of every combination of two of the four possible S-haplotypes. Moreover, the distributions of single S-haplotypes expressed in self- and intercross-pollinated progenies were in disequilibrium. The number of individuals of the two different S-haplotypes was unequal in two self-pollinated and two intercross-pollinated progenies. Notably, the number of individuals containing two different S-haplotypes (S₁- and S₅-, S₅- and S₈-, S₁- and S₄-haplotype) was larger than that of other individuals in the two self-pollinated progenies, indicating that some of these hetero-diploid pollen grains may have the capability to inactivate stylar S-RNase inside the pollen tube and grow better into the ovaries.     

Nitrite oxidase and nitrate reductase in Nitrobacter agilis

Nitrite oxidase and nitrate reductase in Nitrobacter agilis were shown to be separate enzymes. The best separation of the two systems was achieved by ammonium sulphate fractionation. The effects of various compounds, including antimycin A, 2-n-heptyl-4-hydroxyquinoline N-oxide and chlorate, also clearly distinguish between the two enzyme reactions. The relationship between the two opposing reactions in Nitrobacter is discussed.     

Guaianolides and heliangolides from Hymenopappus newberryi

The aerial parts of Hymenopappus newberryi afforded two heliangolides, two thymol derivatives, as well as two new guaianolides and a trans, trans-germacranolide closely related to hiyodorilactone A. Furthermore, the ent-kaurene derivative abbeokutone was present. These results are of chemotaxonomic interest.     

Echinochloa Chloroplast Genomes: Insights into the Evolution and Taxonomic Identification of Two Weedy Species

The genus Echinochloa (Poaceae) includes numerous problematic weeds that cause the reduction of crop yield worldwide. To date, DNA sequence information is still limited in the genus Echinochloa. In this study, we completed the entire chloroplast genomes of two Echinochloa species (Echinochloa oryzicola and Echinochloa crus-galli) based on high-throughput sequencing data from their fresh green leaves. The two Echinochloa chloroplast genomes are 139,891 and 139,800 base pairs in length, respectively, and contain 131 protein-coding genes, 79 indels and 466 substitutions helpful for discrimination of the two species. The divergence between the genus Echinochloa and Panicum occurred about 21.6 million years ago, whereas the divergence between E. oryzicola and E. crus-galli chloroplast genes occurred about 3.3 million years ago. The two reported Echinochloa chloroplast genome sequences contribute to better understanding of the diversification of this genus.     

Combined effects of four Microcystis aeruginosa strains and Scenedesmus obliquus concentrations on population dynamics and resting egg formation of two Daphnia species

We examined the hypothesis that toxic effects of Microcystis aeruginosa to population dynamics, ephippial production, and resting egg formation of Daphnia were restricted by food quality levels. Four unicellular, toxic M. aeruginosa strains with contrasting concentration of microcystin and two Daphnia species were used in this study. The number of offspring at first reproduction, population densities, and maximum population growth rate of two Daphnia species were lower at the highest toxic M. aeruginosa 7820 treatment compared with other treatments under two concentrations of Scenedesmus obliquus. The maximum number of offspring at first reproduction of two Daphnia species appeared in the higher toxic M. aeruginosa 526 strain at the high concentration of S. obliquus. The effects of M. aeruginosa strains, S. obliquus, and their combination on the number of offspring at first reproduction and the maximum population growth rate of two Daphnia species were significant (P < 0.001). Two Daphnia species could not reproduce in the highest toxic M7820 treatment under two concentrations of S. obliquus. They had lower population size and maximum population growth rate in the higher toxic M526 treatment at the low concentration of S. obliquus, but they were higher at the high concentration of S. obliquus. This result suggests that high S. obliquus concentration could relieve the toxicity of M. aeruginosa to Daphnia, and Daphnia could utilize the lower toxic Microcystis as food. The cumulative ephippia numbers of two Daphnia species were more at the high concentration of S. obliquus than those at the low concentration. The percentage of ephippia containing no resting eggs of two Daphnia species was evidently higher at the low concentration of S. obliquus but was lower at the high concentration of S. obliquus. Our results indicated that the cumulative ephippia numbers of Daphnia were population density dependent at the high-level food, and the productions of ephippia in Daphnia were significantly controlled by microcystin concentration at the low-level food.     

Flavonoid chemistry of the endemic species of Myrceugenia (Myrtaceae) of the Juan Fernandez Islands and relatives in continental South America

Twenty-one flavonoids were isolated from the leaves of two endemic species ofMyrceugenia on the Juan Fernandez Islands,M. fernandeziana andM. schulzei, from two related species from Brazil,M. campestris andM. rufescens, and from five species from continental Chile,M. colchaguensis, M. exsucca, M. lanceolata, M. pinifolia, andM. rufa. A phenetic analysis was used to evaluate chemical similarities.Myrceugenia campestris andM. rufescens appear most closely related to each other based on flavonoid profiles, and they are also different from the other seven species. The two endemic species in the Juan Fernandez Islands,M. fernandeziana andM. schulzei, group with the continental Chilean species. The former is most closely related toM. lanceolata, and the latter clusters withM. exsucca, although somewhat distantly. The results suggest that the two Juan Fernandez endemics are derived from two introductions from the Chilean continent and not from immigrants from the eastern side of the Andes.     

Flavonoids of Lupinus texensis and L. subcarnosus

Lupinus texensis and L.- subcarnosus exhibit very similar flavonoid profiles based on O-glycosylflavones, Cglycosylflavones, an isoflavone and a flavanone. Differences between the two species amount to the presence of a diglucoside of diosmetin in L. texensis and comparatively higher concentrations of C-glycosylflavones in L. subcarnosus. The two species have a higher degree of flavonoid pigment similarity than any other pair of lupines examined in our studies. The similar profiles support the view that these two endemic Texan species are closely related.     

Neue phloroglucin-derivate aus Leontonyx-arten sowie weitere verbindungen aus vertretern der tribus inuleae

The investigation of several South African species of the tribe Inuleae afforded in addition to known compounds 16 new constituents. From Leontonyx a group of 9 new phloroglucinol derivatives, from Stoebe species two new p-hydroxyacetophenone, two thymol and two coumaric acid derivatives and from Relhania a new euparine-derivative were isolated. The structures are elucidated mainly by spectroscopic methods. The chemotaxonomic aspects are discussed briefly. The phloroglucinol derivatives, which in part are derived from geraniol, seem to be especially characteristic.     

Millerenolides,sesquiterpene lactones from Milleria quinqueflora

The aerial parts of Milleria quinqueflora afforded 17 new germacranolides (five melampolides and 12 millerenolides), two ent-pimarene and two ent-kaurene derivatives as well as two alicyclic diterpenes and a galactoside. The structures were elucidated by NMR spectroscopy. The chemotaxonomic situation is discussed.     

Two new species of Melanoleuca (Agaricales,Basidiomycota) from northeastern China,supported by morphological and molecular data

Two new species, Melanoleuca leucopoda and M. porphyropoda, are described based on collections made from Shenyang City, Liaoning Province, China. Melanoleuca leucopoda is mainly characterized by its whitish stipe with fibrils and oblong spores with elongated warts. Melanoleuca porphyropoda differs from all other Melanoleuca species in lacking cystidia and in having decurrent gills and a purplish stipe. The sequences of internal transcribed spacer regions (ITS1-5.8S-ITS2) of Melanoleuca species were analyzed and the results indicated that two new species clustered into two clades and differed from the other species of the genus. The combination of morphological and molecular data confirmed that the two fungi are new species. The morphological similarity of the new species to other species of Melanoleuca and the systematic position of the two species based on molecular data are also discussed.     

A COI Nonsynonymous Mutation as Diagnostic Tool for Intraspecific Discrimination in the European Anchovy Engraulis encrasicolus (Linnaeus)

The European anchovy, Engraulis encrasicolus, is currently one of the principal target species for commercial fisheries in Europe. In this study, the mitochondrial Control Region (CR) and the Cytochrome Oxidase I (COI) mitochondrial gene were analyzed in 74 specimens of E. encrasicolus from four localities in the central Mediterranean. In both populations, the two markers revealed the presence of two main haplogroups, A and B, already detected in previous investigations of different classes of molecular markers. Both CR and COI markers consistently identified two haplogroups. The COI sequence analysis identified a non-synonymous transversion (T to G) at position 116 of the translated sequence, resulting in an amino acid change. All COI sequences of haplogroup A had an amino acid sequence with alanine in this position, while serine was present in the same position in haplogroup B. The two haplogroups A and B were also discriminated by the variable number of TACA elements at the 5’-end of the mitochondrial CR. The selection tests applied to the COI dataset revealed that codon 116 was not under positive selection, that seven amino acid changes were under purifying selection, and that two amino acids were under episodic positive selection.     

Leaf flavonoids from Croton urucurana and C. floribundus (Euphorbiaceae)

Flavonoids were isolated by PVPP column chromatography of leaf extracts of Croton floribundus Spreng and C. urucurana Baill. and identified by NMR and co-chromatography with standards. The two species revealed highly distinct flavonoid profiles. C. urucurana, belonging to the phylogenetically basal section Cyclostigma, yielded the flavone C-glycosides vitexin and orientin, quercetin and the O-glycosides quercetin 7-O-rhamnoside, rhamnitrin and rutin, in addition to tiliroside. Instead, C. floribundus, from the more derived section Lasiogyne, yielded no C-glycosides, but a high diversity of classes of flavonols, including kaempferol, three flavonol O-methyl ethers, isoquercitrin, three tri-O-galactosides, in addition to tiliroside and an isorhamnetin-coumaroyl-O-glycoside. The present work is the first report for Croton of two rhamnosides (isolated from C. urucurana). It is also the first report for Euphorbiaceae of two tri-O-glycosides obtained from C. floribundus. The distribution of flavonoids in the two species as determined by HPLC-DAD of extracts of small leaf samples of herbarium specimens is highly similar with the profiles resulting from isolation of compounds from bulky leaf samples. Differences among specimens of the same species were restricted to relative proportions of individual constituents. The results indicate that flavonoid profiles are effective to characterize and distinguish the two species. The present results, combined with literature data, supports the condition of tiliroside as a marker of Croton and the hypothesis of an evolutionary trend in the genus toward the loss of C-glycosides and a progressive complexity of flavonoid profiles.     

Competition and overlap of Oryzaephilus surinamensis and Plodia interpunctella populations under condition of stored date fruits

Plodia interpunctella and Oryzaephilus surinamensis are found in food storehouses including dates and palm storages. The current study aimed to determine competition and overlap potentials of the two pests of date fruits. Time series models were used to study two species populations and logistic growth model to estimate the effect of density of the species. The results revealed the environmental capacities of O. surinamensis and P. interpunctella were 433 and 1610 (maximum number per 20 g), respectively, and the population growth rates (r) were 1.2 and 1.3, respectively. Ecological balances of the two species were close to each other from the first to the third week. The population of O. surinamensis decreased in the fourth week of the competition. The highest population balance of the two species was in the 14th week. The potential of exploitable ecological niches (e_ij) and the amount of non-exploited ecological niches by any species (z_ij) for O. surinamensis was higher than for P. interpunctella from the 8th week untill the end of sampling period. The overlap of ecological niches in the two species (D) ranged from 0.94 to 1, indicating a complete overlap of temporal activity in the two populations on date palm. The current results of this study can be used by integrated pest management specialists. Information over the effects of species competition on population dynamics and their coexistence can be used to predict population status and to adopt simple pest control methods.     

N-Coronafacoyl-L-isoleucine and N-coronafacoyl-L-alloisoleucine,potential biosynthetic intermediates of the phytotoxin coronatine

Two new naturally-occurring analogues of the phytotoxin coronatine have been isolated from liquid cultures of Pseudomonas syringae pv. glycinea. These have been identified as N-coronafacoyl-L-isoleucine and N-coronafacoyl-L-alloisoleucine by mass spectrometry and by studies of the products of acid hydrolysis of the two compounds. The compounds were purified as a mixture of ca 2:1 composition, but the two parent components were not preparatively separated. The possible significance of the two compounds, to the biosynthesis of coronatine, is discussed.