Flavonoids of Tripodanthus acutifolius inhibit TNF-α production in LPS-activated THP-1 and B16-F10 cells

ETHNOPHARMACOLOGICAL RELEVANCE

T. acutifolius is an endemic species from South America which has been used in traditional medicine since ancient times due to its biological properties, including its anti-inflammatory effects.

AIM OF THE STUDY

The aim of the article is to investigate the inhibitory activity of T. acutifolius over TNF-α production in THP-1 and B16-F10 cells. To achieve this, phytochemical analysis has been used to determine the compounds present in the species with anti-inflammatory effects.

MATERIALS AND METHODS

Leaves and stems of T. acutifolius were extracted with n-heptane, dichloromethane, methanol and water. The resulting extracts were analysed in THP-1 and B16-F10 cells by measuring their inhibitory capacity over the production of TNF-α stimulated with LPS.

RESULTS

The guided-bioassay led to the isolation of 6,2',4'-trimethoxyflavone (1), 5,3',4'-trihydroxy-6,7,8-trimethoxyflavone (2), (E)-2',4'-dihydroxy-6'-methoxy-chalcone (3) and 5,4'-dihydroxy-6,7,8-trimethoxyflavone (4) from the dichloromethanic extract. Compounds showed an inhibitory activity of TNF-⍺ production in THP-1 cells, with IC₅₀ of 2.38 ± 0.02 μM, 12.36 ± 0.17 μM, 1.12 ± 0.01 μM and 8.09 ± 0.04 μM, respectively. In addition, the compounds showed an inhibitory activity of TNF-⍺ production in B16-F10 cells with IC₅₀ of 1.32 ± 0.03 μM, 5.63 ± 0.09 μM, 0.60 ± 0.02 μM and 3.77 ± 0.15 μM, respectively.

CONCLUSIONS

We identified 3 flavones (6,2',4'-trimethoxyflavone, 5,3',4'-trihydroxy-6,7,8-trimethoxyflavone, 5,4'-dihydroxy-6,7,8-trimethoxyflavone) and a chalcone ((E)-2',4'-dihydroxy-6'-methoxy-chalcone) present in the leaves and stems of T. acutifolius. These compounds are an alternative for the treatment of immune-mediated inflammatory disorders, acting as negative modulators over the TNF-α production.

Alkamides from Tropaeolum tuberosum inhibit inflammatory response induced by TNF-α and NF-κB

ETHNO-PHARMACOLOGICAL RELEVANCE

Tropaeolum tuberosum, commonly known as "Mashua", is one of the plants most frequently used by Andean (Peruvian-Bolivian) people as food and medicine. It is used as a remedy against a wide range of diseases, especially those related with inflammation.

OBJECTIVES

This study aims to identify compounds active against inflammatory related conditions.

MATERIALS AND METHODS

A bioassay-guided isolation of anti-inflammatory compounds from black and purple tubers of T. tuberosum was performed measuring TNF-α and NF-κB production in THP-1 monocytic cells.

RESULTS

The bioassay-guided isolation led to one active compound from purple T. tuberosum, N-oleoyldopamine (1), and another active compound from black T. tuberosum, N-(2-Hydroxyethyl)-7Z,10Z,13Z,16Z-docosatetraenamide (2). Both compounds displayed anti-TNF-α activity with IC₅₀ values of 3.12 ± 0.19 μM and 1.56 ± 0.15 μM, respectively. Also, both compounds suppressed NF-κB with IC₅₀ of 3.54 ± 0.02 μM and 1.77 ± 0.07 μM, respectively.

CONCLUSIONS

We identified bioactive compounds from purple and black Tropaeolum tuberosum responsible for their anti-inflammatory activity: N-oleoyldopamine (1) and N-(2-Hydroxyethyl)-7Z,10Z,13Z,16Z-docosatetraenamide (2). This is the first report which isolates these compounds from T. tuberosum and describes their anti-inflammatory activities.

Aqueous extract of Hibiscus sabdariffa inhibits pedestal induction by enteropathogenic E. coli and promotes bacterial filamentation in vitro

Diarrheic diseases account for the annual death of approximately 1.9 million children under the age of 5 years, and it is a major cause of work absenteeism in developed countries. As diarrheagenic bacteria, enteropathogenic Escherichia coli (EPEC) attach to cells in the small intestine, causing local disappearance of microvilli and inducing the formation of actin-rich pedestals that disrupt the intestinal barrier and help EPEC adhere to and infect intestinal cells. Antibiotics and other bioactive compounds can often be found by analyzing traditional medicines. Here a crude aqueous extract of Hibiscus sabdariffa, which typically grows in subtropical and tropical areas and is a popular medicinal tisane in many countries, was analyzed for antibacterial activity against EPEC. In standard microdilution assays, the extract showed a minimum inhibitory concentration of 6.5 mg/ml against EPEC growth. Time-kill kinetics assays demonstrated significant 24 h bactericidal activity at 25 mg/ml. The extract is able to impede pedestal induction. Not only did the extract inhibit preformed pedestals but it prevented pedestal induction as well. Remarkably, it also promoted the formation of EPEC filaments, as observed with other antibiotics. Our results in vitro support the potential of Hibiscus sabdariffa as an antimicrobial agent against EPEC.

Molecular genetics of naringenin biosynthesis, a typical plant secondary metabolite produced by Streptomyces clavuligerus

Background

Some types of flavonoid intermediates seemed to be restricted to plants. Naringenin is a typical plant metabolite, that has never been reported to be produced in prokariotes. Naringenin is formed by the action of a chalcone synthase using as starter 4-coumaroyl-CoA, which in dicotyledonous plants derives from phenylalanine by the action of a phenylalanine ammonia lyase.

Results

A compound produced by Streptomyces clavuligerus has been identified by LC–MS and NMR as naringenin and coelutes in HPLC with a naringenin standard. Genome mining of S. clavuligerus revealed the presence of a gene for a chalcone synthase (ncs), side by side to a gene encoding a P450 cytochrome (ncyP) and separated from a gene encoding a Pal/Tal ammonia lyase (tal). Deletion of any of these genes results in naringenin non producer mutants. Complementation with the deleted gene restores naringenin production in the transformants. Furthermore, naringenin production increases in cultures supplemented with phenylalanine or tyrosine.

Conclusion

This is the first time that naringenin is reported to be produced naturally in a prokariote. Interestingly three non-clustered genes are involved in naringenin production, which is unusual for secondary metabolites. A tentative pathway for naringenin biosynthesis has been proposed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-015-0373-7) contains supplementary material, which is available to authorized users.

Sustainable synthesis of N-acetyllactosamine using an immobilized β-galactosidase on a tailor made porous polymer

An efficient enzymatic synthesis of N-acetyllactosamine has been developed in biosolvents, mediated by the action of an immobilized β-galactosidase on a tailor made porous polymer.

New Phenolics from Baccharis Leaf Exudate

Several lipophilic phenolics were found in leaf resins of Baccharis species, reported earlier to produce terpenoids and flavonoid aglycones. They were identified by NMR and GC/MS studies, respectively. The structure of 2′,4′β-trihydroxy-6′-methoxychalcone from B. salicifolia was confirmed by synthesis. Phenylethyl caffeate and benzyl caffeate were found in B. sarothroides.

Terpenoids and Phenylethyl Esters from the Exudate of the Australian Plant Ozothamnus ledifolius (Asteraceae)

The leaf exudate of Ozothamnus ledifolius, previously reported to contain a series of flavonoid aglycones, mostly consists of a mixture of terpenoids. From this resinous material we now identified four sesquiterpenes, a diterpenediol and two pentacyclic triterpene acids. In the phenolic portion we found three phenylethyl esters.

Destruction of chloroanisoles by using a hydrogen peroxide activated method and its application to remove chloroanisoles from cork stoppers

A chemical method for the efficient destruction of 2,4,6-trichloroanisole (TCA) and pentachloroanisole (PCA) in aqueous solutions by using hydrogen peroxide as an oxidant catalyzed by molybdate ions in alkaline conditions was developed. Under optimal conditions, more than 80.0% TCA and 75.8% PCA were degraded within the first 60 min of reaction. Chloroanisoles destruction was followed by a concomitant release of up to 2.9 chloride ions per TCA molecule and 4.6 chloride ions per PCA molecule, indicating an almost complete dehalogenation of chloroanisoles. This method was modified to be adapted to chloroanisoles removal from the surface of cork materials including natural cork stoppers (86.0% decrease in releasable TCA content), agglomerated corks (78.2%), and granulated cork (51.3%). This method has proved to be efficient and inexpensive with practical application in the cork industry to lower TCA levels in cork materials.

Identification of loci and functional characterization of trichothecene biosynthesis genes in filamentous fungi of the genus Trichoderma

Trichothecenes are mycotoxins produced by Trichoderma, Fusarium, and at least four other genera in the fungal order Hypocreales. Fusarium has a trichothecene biosynthetic gene (TRI) cluster that encodes transport and regulatory proteins as well as most enzymes required for the formation of the mycotoxins. However, little is known about trichothecene biosynthesis in the other genera. Here, we identify and characterize TRI gene orthologues (tri) in Trichoderma arundinaceum and Trichoderma brevicompactum. Our results indicate that both Trichoderma species have a tri cluster that consists of orthologues of seven genes present in the Fusarium TRI cluster. Organization of genes in the cluster is the same in the two Trichoderma species but differs from the organization in Fusarium. Sequence and functional analysis revealed that the gene (tri5) responsible for the first committed step in trichothecene biosynthesis is located outside the cluster in both Trichoderma species rather than inside the cluster as it is in Fusarium. Heterologous expression analysis revealed that two T. arundinaceum cluster genes (tri4 and tri11) differ in function from their Fusarium orthologues. The Tatri4-encoded enzyme catalyzes only three of the four oxygenation reactions catalyzed by the orthologous enzyme in Fusarium. The Tatri11-encoded enzyme catalyzes a completely different reaction (trichothecene C-4 hydroxylation) than the Fusarium orthologue (trichothecene C-15 hydroxylation). The results of this study indicate that although some characteristics of the tri/TRI cluster have been conserved during evolution of Trichoderma and Fusarium, the cluster has undergone marked changes, including gene loss and/or gain, gene rearrangement, and divergence of gene function.

A preparative method for the purification of isopenicillin N from genetically blocked Acremonium chrysogenum strain TD189: studies on the degradation kinetics and storage conditions

A protocol for preparative isopenicillin N (IPN) purification, a highly interesting and hitherto unavailable intermediate of the penicillin and cephalosporin biosynthetic pathway due to its high unstability, is described. Culture broths of Acremonium chrysogenum TD189, a strain blocked in cephalosporin biosynthesis that accumulates this metabolite, were treated with acetone and filtered though charcoal and a hydrophobic resin in a single step as tandem columns. The cleared broth was then lyophilized and passed though a Sephadex G-25 column. The last step was the purification to homogeneity of IPN in a semipreparative HPLC equipment and, optionally, a desalting step by Sephadex G-10 column. Once purified, a complete analysis of the stability of the compound and the conditions for its long-term storage was carried out. Our results suggest a first-order model for IPN decomposition for all the pH and temperature analyzed. IPN is more stable at neutral pH, and once lyophilized, can be stored under vacuum and -75 ° C with a half-life of 770 days.

Characterization of an hyperpigmenting mutant of Monascus purpureus IB1: identification of two novel pigment chemical structures

Monascus purpureus IB1 produces about 50-fold higher levels of azaphilone pigments than M. purpureus NRRL1596. Differently pigmented mutants were obtained from M. purpureus IB1 by nitrosoguanidine treatment. A highly pigmented strain, M. purpureus HP14, was found to lack the formation of the classical yellow and orange azaphilones and was found to produce only about 10% of the red azaphilone pigments. The intense color was associated with novel pigments as shown by high-performance liquid chromatography (HPLC). The addition of hexanoic acid to M. purpureus IB1 resulted in higher volumetric and specific red pigment productivity, but in a complete absence of the classical orange azaphilones, while the classical yellow and red azaphilone pigments were severely reduced; new peaks corresponding to less hydrophobic pigments were found in hexanoic-supplemented cultures by HPLC. Purification of pigments from hexanoic-supplemented cultures showed the presence of five new pigments as indicated by the absorption spectra and HPLC analysis. Two of them, R3 and Y3, were characterized by nuclear magnetic resonance as 9-hexanoyl-3-(2-hydroxypropyl)-6a-methyl-9,9a-dihydro-6H-furo[2,3-h]isochromene-6,8(6aH)-dione and 4-[2,4-dihydroxy-6-(3-hydroxybutanethioyloxy)-3-methylphenyl]-3,4-dihydroxy-3,6-dimethylheptanoic acid. These pigments were also found to be present in cultures of the high-producing mutant M. purpureus HP14. These new pigments are less hydrophobic than the classical azaphilones and may have better properties as natural colorants in the food industry.

PI Factor, a Novel Type Quorum-sensing Inducer Elicits Pimaricin Production in Streptomyces natalensis

A chemically novel autoinducer (PI factor) has been purified from cultures of the pimaricin producer Streptomyces natalensis ATCC27448. The chemical structure of the PI molecule was identified as 2,3-diamino-2,3-bis (hydroxymethyl)-1,4-butanediol. Pimaricin biosynthesis in S. natalensis npi287, a mutant impaired in pimaricin production, was restored by supplementation with either A-factor from Streptomyces griseus IFO13350 or with PI factor. S. natalensis did not synthesize A-factor. The PI autoinducer was active at very low concentrations (50-350 nm). A threshold level of 50 nm was required to observe the induction effect. The dose-response curve was typical of a quorum-sensing type mechanism. The biosynthesis of PI factor was associated with cell growth of S. natalensis, both in defined and complex media. Supplementation of the wild-type S. natalensis with pure PI (300 nm) resulted in a stimulation of 33% of the production of pimaricin. These results indicate that the endogenous synthesis of PI factor is limiting for pimaricin biosynthesis in the wild-type strain. This water-soluble PI factor belongs to a novel class of autoinducers in Streptomyces species different from the classical butyrolactone autoinducers. Because restoration of pimaricin production in the npi287 mutant is conferred by both A-factor and PI factor, S. natalensis appears to be able to integrate different quorum signals from actinomycetes.

Isoangoroside C, a phenylpropanoid glycoside from Scrophularia scorodonia roots

A new phenylpropanoid glycoside isoangoroside C was isolated from the roots of Scrophularia scorodonia. Its structure was determined on the basis of spectral data as: 3-hydroxy-4-methoxy-beta-phenylethoxy-O-alpha-L-arabinopyranosy l-(1-->6)alpha L-rhamnopyranosyl-(1-->3)-4-O-Z-feruloyl-beta-D-glucopyranoside. Additionally, one known phenylpropanoid, angoroside C, and five known iridoid glycosides, harpagoside, bartsioside, 8-O-acetyl-harpagide, aucuboside and harpagide were isolated and identified.

New constituents of the leaf and stem exudate of Ozothamnus hookeri (Asteraceae)

The exudate of Ozothamnus hookeri has been investigated for its non-flavonoid constituents. A new natural C6-C3 ester of a long chain fatty acid and seven structurally related kaurane-diterpenoids were isolated. Three of the latter are new natural products, too. A rare 8-methoxy flavonol was also identified.

A new oxyprenyl coumarin and highly methylated flavones from the exudate of Ozothamnus lycopodioides (Asteraceae)

A new oxyprenyl coumarin was isolated from the lipophilic exudate of Ozothamnus lycopodioides. Its structure was established as 7-(3,3'-dimethylallyloxy)-5-hydroxy-6-methoxycoumarin from its UV, MS and NMR spectral data, especially two dimensional experiments. In addition to six earlier reported flavonols, we found four highly substituted flavones, including two rare methylenedioxyflavones.

16α,19-Diacetoxy-ewf-kaurane, a New Natural Diterpene from the Exudate of Ozothamnus scutellifolius (Asteraceae)

Leaf and stem exudate of Ozothamnus scutellifolius, previously reported to contain 21 flavonoid aglycones, was now investigated for its terpenoid composition. Seven structurally related diterpenoids were identified. One of them, 16a,19-diacetoxy-enf-kaurane, is a novel natural product.

Delta-1-piperideine-6-carboxylate dehydrogenase, a new enzyme that forms alpha-aminoadipate in Streptomyces clavuligerus and other cephamycin C-producing actinomycetes

Delta-1-Piperideine-6-carboxylate (P6C) dehydrogenase activity, which catalyses the conversion of P6C into alpha-aminoadipic acid, has been studied in the cephamycin C producer Streptomyces clavuligerus by both spectrophotometric and radiometric assays. The enzyme has been purified 124-fold to electrophoretic homogeneity with a 26% yield. The native protein is a monomer of 56.2 kDa that efficiently uses P6C (apparent Km 14 microM) and NAD+ (apparent Km 115 microM), but not NADP+ or other electron acceptors, as substrates. The enzyme activity was inhibited (by 66%) by its end product NADH at 0.1 mM concentration. It did not show activity towards pyrroline-5-carboxylate and was separated by Blue-Sepharose chromatography from pyrroline-5-carboxylate dehydrogenase, an enzyme involved in the catabolism of proline. P6C dehydrogenase reached maximal activity later than other early enzymes of the cephamycin pathway. The P6C dehydrogenase activity was decreased in ammonium (40 mM)-supplemented cultures, as was that of lysine 6 amino-transferase. P6C dehydrogenase activity was also found in other cephamycin C producers (Streptomyces cattleya and Nocardia lactamdurans) but no in actinomycetes that do no produce beta-lactams, suggesting that it is an enzyme specific for cephamycin biosynthesis, involved in the second stage of the two-step conversion of lysine to alpha-aminoadipic acid.

Three Further Dammarane Type Triterpenes from the Frond Exudate of the Fern Notholaena rigida

From the farinose frond exudate of the fern Notholaena rigida two new triterpenes have been identified. They were found to be the C-24 epimers of 3β-acetoxy- 24, 25-diO-isopropylidene-12β, 20(S),24,25-tetrahydroxy- dammarane. A third triterpene is identical with the known compound pyxinol, (20S,24R)-20.24-epoxydammarane- 3β,12β,25-triol

Two New Triterpenes from the Frond Exudate of the Fern Notholaena rigida

From the farinose frond exudate of the fern Notho­laena rigida two new triterpenes have been identified. They were found to be the C-24 epimers of 24, 25-diO-isopropylidene-3β, 12β, 20(S)-trihydroxy-dammarane.