Flavonoids of the liverwort Marchantia foliacea

The major flavonoids of Marchantia follacea are the 7-O-β-d-glucuronides of apigenin, chrysoeriol and tricin, and apigenin-6,8-di-C-glucoside (vicenin-2). Minor constituents include the rhamnosylglucuronides of the above flavones. Apparent isomerization of the glucuronides on hydrolysis (MeOH-HCl) proved to be due to methylation of the sugar carboxyl group.     

Flavonoids in leaves and inflorescences of australian cyperaceae

A survey of 170 Australian species of Cyperaceae belonging to 35 genera has confirmed that this family has a highly characteristic flavonoid pattern in leaf and inflorescence. Aurone pigments, the most distinctive family constituents, were found in the leaves of 25% of the sample and in the inflorescences of 40%. Sulphuretin was found for the first time in the family, in Carex appressa. Flavones, such as tricin and luteolin, are very common; in addition, a variety of methyl ethers were detected. Luteolin 5-methyl ether was found in further genera, while luteolin 7-methyl ether, diosmetin and acacetin were detected for the first time in the Cyperaceae. Flavonols and their methyl ethers occurred in over one-third of the species, particularly in the leaves, being especially well represented in the genera Fuirena, Gahnia, Lepidosperma and Mesomelaena. Myricetin was found only twice, in two Baumea species. The 3-desoxyanthocyanidin carexidin was found in the inflorescences of eight species, i.e. in 5% of the sample. Taxonomically, the results are mainly of interest at the generic and specific level, where the patterns sometimes show useful correlations with morphology. At the tribal level, the Sclerieae are the most distinctive, with higher than average frequency of flavone C-glycosides, flavonols, proanthocyanidins and aurones, and lower than average frequency of flavones.     

Biosystematics of the monocotyledoneae—flavonoid patterns in leaves of the liliaceae

In a leaf survey of 168 species of the Liliaceae, most of the major flavonoid classes were found to be represented in the family. Flavonols occurred most frequently: quercetin and kaempferol were detected in 40% and 42% of the sample respectively, while the flavones luteolin and apigenin were present in only 24% and 20% of the sample. Methylated derivatives, i.e. isorhamnetin, diosmetin and tricin were rare. Procyanidins were present in 17 species, flavonoid sulphates in only one species and flavone C-glycosides in only three species. Anthraquinone pigments were identified in species of Aloe Asphodeline and Asphodelus. Three new flavonoid glycosides were characterised during the course of the survey: diosmetin 7-diglucoside in Colchicum byzanthinum and tricin 7-fructosylglucoside and tricin 7-rutinoside-4′-glucoside in Hyacinthus orientalis cv. ‘Quean of the Pinks’. On the basis of the flavonoid survey, the subfamilies of the Liliaceae may be grouped into those containing flavonols only, those with flavones only or those having both flavonols and flavones. Members of the related families: Amaryllidaceae (17 species), Agavaceae (1 species) and Xanthorrhoeaceae (1 species) contained only flavonols. The subfamilies Scilloideae, Asphodeloideae and Melanthioideae show the most chemical variation whilst the Wurmbaeoideae and Lilioideae are the most homogeneous groups. The tribe Scilleae is unusual in that both flavone- and flavonol-containing genera occur and a wide variety of flavonoid types are represented. A comparison of the leaf flavonoids of the Liliaceae with those found in families related to the grasses showed that all except two classes of flavonoid compound (5-methylated flavones and 5-deoxyflavonoids) found in the Juncaceae. Cyperaceae, Palmae and Gramineae are present in the Liliaceae thus supporting the view that all four families could have arisen from Liliaceae-like ancestors.     

The structures of new flavone di-C-glycosides from Apometzgeria pubescens

The structures of seven flavone C-glycosides from Apometzgeria pubescens were determined with the aid of ¹³CNMR spectroscopy. They were all     

Flavonoids in leaves and inflorescences of australian Cyperus species

A survey of the flavonoids of some 92 species of Australian Cyperus, mainly of subtropical or tropical origin, has confirmed a correlation previously reported in this family between flavonoid pattern and plant geography. The pattern found was similar to that of African and South American Cyperaceae, particularly in the occurrence of the rare marker substance, luteolin 5-methyl ether. Tricin and luteolin are relatively common, in glycosidic form, in the leaves while the flavonol quercetin is infrequent. When present, quercetin occurs either in glycosidic form or free as a methyl ether. The 3-monomethyl and 3, 7-dimethyl ethers of kaempferol and quercetin and the 3, 7, ?-trimethyl ether of quercetin are reported for the first time from the Cyperaceae. The flavonoid pattern of inflorescences is distinct from that of the leaves in that tricin is not detectable and that luteolin 5-methyl ether appears to be replaced by 7, 3′, 4′-trihydroxyflavone. In addition, the aurone aureusidin is more commonly present than in the leaves and is occasionally accompanied by two further aurones. The glycoxanthones mangiferin and isomangiferin occur rarely in all three species examined in the section Haspani, i.e. in C. haspan, C. prolifer and C. tenuispica. In general, however, the flavonoid data do not offer any markers which separate off different sections within the genus; there are, however, some significant correlations between the frequency of the flavonoid classes and subgeneric groupings.     

5,7,3′-Trihydroxy-4′,5′-dimethoxyflavone and other phenolics from Poa huecu

Whole plants of Poa huecu have yielded a new flavone characterized as 5,7,3′-trihydroxy-4′,5′-dimethoxyflavone as well as tricin, selagin, umbelliferone and scopoletin.     

Negatively charged flavones and tricin as chemosystematic markers in the palmae

A survey of 125 species of the Palmae revealed a complex pattern of flavonoids in the leaf. C-Glycosylflavones, leucoanthocyanins and tricin, luteolin and quercetin glycosides were common, being present in 84, 66, 51, 30 and 24% of the species respectively. Apigenin and kaempferol were recorded in only a few species and isorhamnetin only once. Eighteen flavonoids were identified: the 7-glucoside, 7-diglucoside and 7-rutinoside of both luteolin and tricin, tricin 5-glucoside, apigenin 7-rutinoside, quercetin 3-rutinoside-7-galactoside, isorhamnetin 7-rutinoside, orientin, iso-orientin, vitexin, isovitexin and vitexin 7-O-glucoside. Many of the C- and O-flavonoid glycosides were present as the potassium bisulphate salts and negatively charged compounds were detected in 50% of the species. The distribution patterns are correlated with the taxonomy of the family in several ways. Thus, the Phoenicoideae and Caryotoideae have distinctive flavonoid patterns, there is evidence to support the separation of the subfamilies Phytelephantoideae and Nypoideae, and tricin is a useful marker at tribal level. At the generic level, Cocos is clearly separated from Butia, and other Cocoseae and Mascarena and Chamaedorea form well defined groups within the Arecoideae. A numerical analysis of these biochemical data, together with morphological characters, produces a new classification which suggests that the flavonoid data may have more systematic value than is indicated when they are applied to the traditional classification.     

Apport de la biochimie flavonique à la systematique du genre Lycopodium

A systematic study of Lycopodium s.l. shows that only flavones occur in the four genera Huperzia, Lepidotis, Lycopodium s.s. and Diphasium. The arrangement of these taxa is discussed on the basis of the distribution of tricin, selgin, chrysoeriol, luteolin and apigenin. The evolutionary significance of these results and the uniqueness of Lycopodium phenolic metabolism are outlined.     

Flavonoid pigments of butterflies in the genus Melanargia

Flavonoid pigments (18) were identified in the wings and body of Melanargia galathea: tricin, tricin 7-glucoside, tricin 7-diglucoside, tricin 4′-glucoside, luteolin, luteolin 7-glucoside, luteolin 7-diglucoside, luteolin 7-triglucoside, apigenin, apigenin 7-glucoside, orientin, orientin 7-glucoside, iso-orientin, iso-orientin 7-glucoside, vitexin 7-glucoside, vitexin 7-glucoside, isovitexin, isovitexin 7-glucoside and a novel but incompletely identified tricin 4′-conjugate. Examination of the wings and bodies of individual M. galathea, M. galathea var. procida, M. lachesis, M. russiae, M. larissa, M. occitanica and M. ines butterflies from a number of different populations in Europe by 2D PC revealed that variation in their flavonoid patterns was so minor that the flavonoid pattern of these Melanargia spp. may be considered constant. The concentration of flavonoids in the wings of each butterfly was greater than that in the body, as is the covering of scales. Not all flavonoids are located in the scales; some are also located in the reproductive tissues of the female. With the exception of the tricin 4′-conjugate which was absent from the egg and first instar larvae before feeding commences, these flavonoids were present in all the life stages of M. galathea. The presence of tricin 4′-conjugate in Melanargia but its absence from the larval food plants suggests that this compound is synthesized by the insect and that flavonoids are not merely sequestered from the diet but are also partly metabolized.     

Feeding deterrency of flavonoids and related phenolics towards Schizaphis graminum and Myzus persicae: Aphid feeding deterrents in wheat

A number of naturally occurring flavonoids have been tested for their feeding deterrent activity against two aphid species, Schizaphis graminum and Myzus persicae. Most flavonoids, including a number of dihydrochalcones related to phloretin, showed strong deterrency at concentrations well within the range often found in plants. Flavanone and flavone glycosides showed weak feeding deterrency relative to their corresponding aglycones. S. graminum and M. persicae responded similarly towards the compounds tested. The feeding deterrency of wheat extracts towards S. graminum was confined to the phenolic fraction, which included the flavone tricin. The more polar phenolic fraction showed the strongest feeding deterrency towards S. graminum.     

Enzymatic synthesis of β-lactam antibiotics: A thermodynamic background

The equilibrium constants and the respective standard Gibbs energy changes for hydrolysis of some β-lactam antibiotics have been determined. Native and immobilized penicillin amidase (EC 3.5.1.11) from Escherichia coli has been used as a catalyst. The values of standard Gibbs energy changes corresponding to the pH-independent product of equilibrium concentrations (ΔG⁰_c = ? RT ln K_c) have been calculated. The differences in the structure of the antibiotics nucleus hardly ever affect the value of the pH-independent component of the standard Gibbs energy change (ΔG⁰_c) and value of apparent standard Gibbs energy change at a fixed pH (ΔG^0′_c). At the same time, the value of ΔG⁰_c is more sensitive to the structure of the acyl moiety of the antibiotic; when ampicillin is used instead of benzylpenicillin, ΔG⁰_c increases by ～6.3 kJ mol^?1 (1.5 kcal mol^?1). pH-dependences of the apparent standard Gibbs energy changes for hydrolysis of β-lactam antibiotics have been calculated. The pH-dependences of ΔG^0′_c for hydrolysis of all β-lactam antibiotics have a similar pattern. The thermodynamic pH optimum of the synthesis of these compounds is in the acid pH range (pH < 5.0). The breakage of the β-lactam ring leads to a sharp decrease in the ΔG^0′_c value and a change in the pattern of the pH-dependence. For example, at pH 5.0 ΔG^0′_c decreases from 14.4 kJ mol^?1 for benzylpenicillin to ?1.45 kJ mol^?1 for benzylpenicilloic acid. The reason for these changes is mainly a considerable increase in the pK of the amino group of the nucleus of the antibiotic and, as a consequence, a decrease in the component of standard Gibbs energy change, corresponding to the ionization of the system. The thermodynamic potentials of the enzymatic synthesis of semisynthetic penicillins and cephalosporins on the basis of both free acids and their derivatives (N-acylated amino acids, esters) are discussed. It is shown that with esters of the acids, a high yield of the antibiotic can, in principle, be achieved at higher pH values.     

Novel tetrahydropyrido[3,2-c]pyrroles as 5-HT(7) antagonists

The synthesis and SAR for a novel series of tetrahydropyrido[3,2-c]pyrroles is described. Optimization of the pendant aryl ring lead to high binding affinity at the 5-HT₇ receptor when small lipophilic groups were placed in the para position. Modification of the N-benzyl group and secondary amine were not well tolerated. A representative set of compounds was shown to be functional antagonists of the 5-HT₇ receptor.     

Multiple-site mutations of phage Bp7 endolysin improves its activities against target bacteria

The widespread use of antibiotics has caused serious drug resistance. Bacteria that were once easily treatable are now extremely difficult to treat. Endolysin can be used as an alternative to antibiotics for the treatment of drug-resistant bacteria. To analyze the antibacterial activity of the endolysin of phage Bp7(Bp7e), a 489-bp DNA fragment of endolysin Bp7e was PCR-amplified from a phage Bp7 genome and cloned, and then a p ET28a-Bp7e prokaryotic expression vector was constructed. Two amino acids were mutated(L99A, M102E) to construct p ET28a-Bp7Δe, with p ET28a-Bp7e as a template. Phylogenetic analysis suggested that BP7e belongs to a T4-like phage endolysin group. Bp7e and its mutant Bp7Δe were expressed in Escherichia coli BL21(DE3) as soluble proteins. They were purified by affinity chromatography, and then their antibacterial activities were analyzed. The results demonstrated that the recombinant proteins Bp7e and Bp7Δe showed obvious antibacterial activity against Micrococcus lysodeikticus but no activity against Staphylococcus aureus. In the presence of malic acid, Bp7e and Bp7Δe exhibited an effect on most E. coli strains which could be lysed by phage Bp7, but no effect on Salmonella paratyphi or Pseudomonas aeruginosa. Moreover, Bp7Δe with double-site mutations showed stronger antibacterial activity and a broader lysis range than Bp7e.     

Flavonoid variation in the genus briza

During a survey of 6 Eurasian and 10 South American Briza species for leaf flavonoids, 27 components were found. Twelve of these were identified: tricin 5-glucoside, tricin 7-glucoside, quercetin 3-glucoside, kaempferol 3-glucoside, vitexin, isovitexin, orientin, iso-orientin, and the 4′-O-glucoside of all 4 glycoflavones, 3 of which are reported for the first time. The Eurasian species, with the exception of Briza maxima, are remarkably uniform in their flavonoid pattern, accumulating mainly vitexin and isovitexin; whereas the South American species are characterized by the presence of orientin, iso-orientin and 9 unidentified flavonoids. In Briza media and the South American species, ploidy level is shown to play a large part in flavonoid variation. Examination of 12 diploid and 8 autotetraploid plants of B. media revealed that diploids accumulate vitexin and isovitexin, whereas tetraploids accumulate orientin and iso-orientin, autotetraploidy having apparently upset regulatory genes in the formation of the flavone C-glycosides. Mild alkaline treatment of both isovitexin and iso-orientin was found to give 100% conversion to the corresponding 8-C-glucoside.     

Cumarine aus südafrikanischen Pelargonium-arten

From the roots of Pelargonium reniforme 7-hydroxy-5,6-dimethoxycoumarin, its monomethyl ether and its 7-O-glucoside were isolated for the first time. This coumarin, its 7-glucoside and scopoletin were detected chromatographically in the roots of eleven other South African Pelargonium species.     

7-Oxo-, 7α-hydroxy- and 7β-hydroxysterols from Euphorbia fischeriana

7-Oxo, 7α-hydroxy- and 7β-hydroxysterols (campesterol, stigmasterol and sitosterol derivatives) were isolated from the roots of Euphorbia fischeriana, a drug used for its antitumour properties in traditional Chinese medicine. Some of these steroids show antitumour activity and might be related to the presumed activity of the drug.     

Kinetics of formation of O6-ethylguanine in,and its removal from liver DNA of rats receiving diethylnitrosamine

The ethylation of rat liver DNA by a single dose of diethylnitrosamine and the stability of O⁶-ethylguanine in vivo were studied. Whereas the dose response relations for 7-ethylguanine, 3-ethyladenine, the pyrimidine oligonucleotide fraction containing ethylphosphotriesters and an as yet unreported Fraction X corresponded with a first-order process of formation, the results suggested a steeper dose-response relation for O⁶-ethylguanine formation. In the dose range 0.5–10 mg/kg diethylnitrosamine, the O⁶-ethylguanine/7-ethylguanine ratio increased progressively with the dose, under conditions in which the in vivo stability (removal rate) of O⁶-ethylguanine was not affected. This led to the hypothesis that the formation of O⁶-ethylguanine, but not that of the other ethylated products, was facilitated by some dose-dependent process or condition. Support for this view was obtained by the markedly enhanced O⁶-[¹⁴C]ethylguanine content of DNA following pretreatment of the rats with non-radioactive diethylnitrosamine which was allowed to be metabolized completely prior to the administration of a tracer dose of [¹⁴C]diethylnitrosamine. Since neither the amounts of the other ethylation products nor the stability of the labelled O⁶-ethylguanine were affected by the pretreatment, changes in carcinogen metabolism or excision rate could be excluded as causes of the observed increase in O⁶-ethylguanine content. The half-life of the condition that facilitates O⁶-ethylguanine formation following pretreatment, may approximate that of O⁶-ethylguanine itself. The nature of the facilitating process and the possible role of O⁶-alkylguanine in hepatocarcinogenesis are discussed.     

Metformin inhibits MAPK signaling and rescues pancreatic aquaporin 7 expression to induce insulin secretion in type 2 diabetes mellitus

Metformin is the first-line antidiabetic agent for type 2 diabetes mellitus (T2DM) treatment. Although accumulated evidence has shed light on the consequences of metformin action, the precise mechanisms of its action, especially in the pancreas, are not fully understood. Aquaporin 7 (AQP7) acts as a critical regulator of intraislet glycerol content, which is necessary for insulin production and secretion. The aim of this study was to investigate the effects of different doses of metformin on AQP7 expression and explore the possible mechanism of its protective effects in the pancreatic islets. We used an in vivo model of high-fat diet in streptozocin-induced diabetic rats and an in vitro model of rat pancreatic β-cells (INS-1 cells) damaged by hyperglycemia and hyperlipidemia. Our data showed that AQP7 expression levels were decreased, whereas p38 and JNK mitogen-activated protein kinases (MAPKs) were activated in vivo and in vitro in response to hyperglycemia and hyperlipidemia. T2DM rats treated with metformin demonstrated a reduction in blood glucose levels and increased regeneration of pancreatic β-cells. In addition, metformin upregulated AQP7 expression as well as inhibited activation of p38 and JNK MAPKs both in vivo and in vitro. Overexpression of AQP7 increased glycerol influx into INS-1 cells, whereas inhibition of AQP7 reduced glycerol influx, thereby decreasing subsequent insulin secretion. Our findings demonstrate a new mechanism by which metformin suppresses the p38 and JNK pathways, thereby upregulating pancreatic AQP7 expression and promoting glycerol influx into pancreatic β-cells and subsequent insulin secretion in T2DM.     

Toxoplasma CRISPR/Cas9 constructs are functional for gene disruption in Neospora caninum

Herein we describe, to our knowledge for the first time the use of the clustered regularly interspaced short palindromic repeats/CRISPR-associated gene 9 (CRISPR/Cas9) system for genome editing of Neospora caninum, an apicomplexan parasite considered one of the main causes of abortion in cattle worldwide. By using plasmids containing the CRISPR/Cas9 components adapted to the closely related parasite Toxoplasma gondii, we successfully knocked out a green fluorescent protein (GFP) in an Nc-1 GFP-expressing strain, and efficiently disrupted the NcGRA7 gene in the Nc-Spain7 isolate by insertion of a pyrimethamine resistance cassette. The successful use of this technology in N. caninum lays the foundation for an efficient, targeted gene modification tool in this parasite.     

Spatiotemporal expression pattern of Sjfz7 and its expression comparison with other frizzled family genes in developmental stages of Schistosoma japonicum

Wnts are secreted signaling molecules that are implicated in a variety of growth-related processes. Frizzled proteins have been identified as receptors for Wnt ligands in vertebrates and invertebrates, but a functional role for dioecious flatworm Frizzleds has not been determined. To evaluate the endogenous role of Frizzled proteins during development, we have identified and characterized a Schistosoma japonicum frizzled gene (Sjfz7). We found that Sjfz7 encodes a 698 amino acid protein with typical characteristics of Frizzled proteins. The immunohistochemical localization pattern showed that Sjfz7 protein was extensively distributed in almost all tissues of S. japonicum, including subtegumental muscle cells, parenchymal cells, intestinal epithelial cells and male and female germ cells. This indicated that Sjfz7-mediated Wnt signaling might be associated with the development of musculature, intestinal tract and reproductive organs in schistosome. Comparing mRNA levels between frizzled family members showed that Sjfz7 mRNA was consistently higher in the developmental stages analyzed, suggesting that Sjfz7 may be responsible for more functional tasks than other frizzled family members. Comparing frizzled mRNA levels between not fully developed and normal worms suggested that Wnt signaling might be abnormal in not fully developed worms.