Plumbagin, Juglone, and Boropinal as Novel TRPA1 Agonists

A series of seven oxyprenylated phenylpropanoids and naphthoquinones were tested regarding their ability to activate transient receptor potential ankyrin subtype 1 channel (TRPA1). Three of the assayed compounds, namely, boropinal (3), juglone (5), and plumbagin (7), acted as strong modulators of TRPA1 channels with EC50 values of 9.8, 1.7, and 0.5 μM, respectively, as assessed by Ca(2+) assays. Moreover, the compounds elicited TRPA1 currents in electrophysiological whole cell recordings. We additionally provide evidence that plumbagin activated TRPA1-positive neurons isolated from mouse dorsal root ganglion neurons but did not affect sensory neurons from TRPA1-deficient mice. The high potencies of plumbagin and juglone to activate TRPA1 channels may explain the molecular basis of the mucosal irritant properties of these compounds as well as of related naphthoquinones and phytopreparations, as widely reported in the literature.

Spatial variations in feeding habits and trophic levels of two small pelagic fish species in the central Mediterranean Sea

Trophic ecology of adults of European sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) was examined and compared among various regions of central Mediterranean Sea. Carbon and nitrogen stable isotope analyses (δ(13)C and δ(15)N) were adopted as a tool to determine changes in feeding behaviour of adults of sardines and anchovies. In the study period (summer) a clear geographical pattern was recognized in the isotopic composition of both species, with an increasing trend northward. The highest variations in isotopic signal were linked to the geographical positions of the samples and, especially, between pairs of areas: South Sicily/South Campania and Gulf of Gaeta/South Elba. Higher isotope values were found in the anchovies and sardines caught in northern Tyrrhenian Sea, while lower values were mostly estimated in the southern region. Higher carbon and nitrogen isotopes may reflect a more coastal behaviour of both species, being (13)C-enriched source from benthic primary producers in addition to phytoplankton. Variations in the nitrogen isotope ratio may reflect not only differences in the trophic level of prey species, but also variations in the baseline level of food webs. Our results support the hypothesis that feeding behaviour of both species is directly or indirectly influenced by local factors, or by resource partitioning based on zooplankton size. Findings can supply knowledge needed for improving fish stock management and promoting plans able to take into account also local ecosystem analysis.

Clinical implications of oxidative stress and potential role of natural antioxidants in diabetic vascular complications

AIMS

The possible link between hyperglycaemia-induced oxidative stress (OxS) and diabetic complications is suggested by many in vitro studies. However, not much attention has been paid to the clinical evidence supporting this hypothesis, as well as to their possible therapeutic implications.

DATA SYNTHESIS

Some prospective studies show a direct correlation between an increase in OxS biomarkers and the appearance of diabetes complications. This is consistent with the evidence that any acute increase of glycaemia, particularly post-prandial, and hypoglycaemia causes endothelial dysfunction and inflammation, through the generation of an OxS. However, the detection of free radicals is difficult as they are highly reactive molecules with a short half-life. Instead, the metabolites of OxS are measured. Interventional trials with supplemented antioxidants have failed to show any beneficial effects. Conversely, natural foods show very promising results.

CONCLUSIONS

The "new antioxidant" approach includes the possibility of controlling free radical production and increasing intracellular antioxidant defence, a concept different from the old one, when antioxidant activities implied scavenging the free radicals already produced. A synergistic action in this respect could convincingly be obtained with a balanced 'Mediterranean Diet' (MedD) type. Early intensive glucose control is still the best strategy to avoid OxS and its associated diabetes complications.

Lispro insulin in people with non-alcoholic liver cirrhosis and type 2 diabetes mellitus

AIMS

To compare metabolic control under lispro and recombinant regular human insulin (RHI) in people with diet-unresponsive type 2 diabetes mellitus (T2DM) and compensated non-alcoholic liver disease (CLD).

METHODS

108 people with T2DM and CLD were randomly allocated to RHI or lispro according to a 12+12 week cross-over protocol. A 1-week continuous glucose monitoring (CGM) session was performed at the end of each treatment period followed by a standard meal test with a 12IU lispro or RHI shot ahead.

RESULTS

CGM showed higher glycemic excursions under RHI than under lispro (p<0.01) with lower glucose levels in the late post-absorption phase (p<0.05) and even more during the night (p<0.01). Post-challenge incremental areas under the curve (ΔAUC) were undistinguishable for insulin but lower for glucose, while insulin peaked higher and earlier and glycemic excursions were lower with lispro than with RHI (0.05<p<0.001).

CONCLUSIONS

Lispro granted lower early postprandial glucose levels and late postprandial hypoglycemic rates and therefore might represent the treatment of choice for people with T2DM and compensated CLD. This might depend on its faster/shorter-living effects, as well as, on the lower liver glucose output expected from its earlier hepatic distribution.

Cytotoxic Activity of Lomatiol and 7-(3′-Hydroxymethyl-3′-methylallyloxy)coumarin

7-(3′-Hydroxymethyl-3′-methylallyloxy)coumarin, bearing a 3′-hydroxy-3′-methylallyl group as the O-side chain, and lomatiol, a lapachol derivative sharing the same structural feature, were tested for their in vitro growth inhibitory activities on six cancer cell lines using the MTT colorimetric assay, along with the respective 3′,3′-dimethylallyl derivatives and unprenylated products used for comparison. Data revealed that lomatiol displayed the strongest growth inhibitory activities in vitro although not as efficient as the parent compound lapachol. The oxidized O-prenylcoumarin recorded better growth inhibitory capacities than the prenylated and unprenylated parent products.

Cytotoxic Activity of Lomatiol and 7-(3'-Hydroxymethyl-3'-methylallyloxy)coumarin

7-(3'-Hydroxymethyl-3'-methylallyloxy)coumarin, bearing a 3'-hydroxy-3'-methylallyl group as the O-side chain, and lomatiol, a lapachol derivative sharing the same structural feature, were tested for their in vitro growth inhibitory activities on six cancer cell lines using the MTT colorimetric assay, along with the respective 3',3'-dimethylallyl derivatives and unprenylated products used for comparison. Data revealed that lomatiol displayed the strongest growth inhibitory activities in vitro although not as efficient as the parent compound lapachol. The oxidized O-prenylcoumarin recorded better growth inhibitory capacities than the prenylated and unprenylated parent products

Novel juglone and plumbagin 5-O derivatives and their in vitro growth inhibitory activity against apoptosis-resistant cancer cells

Juglone 1 an plumbagin 2 are plant secondary metabolites nowadays well known for their anticancer properties. In this study we synthesized analogues of 1 and 2 deriving from the functionalization of the OH group in position 5 with different side chains in form of esters and ethers. Therefore the growth inhibitory activities of these adducts were evaluated in vitro on six cancer cell lines using the MTT colorimetric assays along with the two natural parent compounds. The data revealed that these latter displayed the strongest growth inhibitory activities in vitro. Quantitative videomicroscopy analyses were then carried out on human U373 glioblastoma cells, which are characterized by various level of resistance to pro-apoptotic stimuli. We compared the naturally occurring reference compounds 1 and 2 with the derivatives exerting the best activities in terms of IC50 growth inhibitory values. These analyses showed that both juglone and plumbagin had a cytostatic effect on U373 cells and were able to overcome the intrinsic resistance of U373 cancer cells to pro-apoptotic stimuli.

Synthesis of the Furan Nucleus Promoted by Ytterbium Triflate

An efficient synthesis of differently substituted furans from acetylene dicarboxylates and β-dicarbonyl compounds is described. The furan nucleus was built by means of an Yb(OTf)3 catalyzed cycloaddition reaction yielding desired adducts in 91%-98% yield.

Synthesis of the Furan Nucleus Promoted by Ytterbium Triflate

An efficient synthesis of differently substituted furans from acetylene dicarboxylates and β-dicarbonyl compounds is described. The furan nucleus was built by means of an Yb(OTf)3 catalyzed cycloaddition reaction yielding desired adducts in 91% – 98% yield.

Complexes of Lapachol and Lawsone with Lanthanides

Naturally occurring 2-hydroxy-1,4-naphthoquinones are well known to form readily stable complexes with transition metals. In this short communication we describe for the first time the synthesis and preliminary data about structural characterization of complexes between two naturally widespread 2-hydroxy-1,4-naphthoquinones, namely lapachol (1) and lawsone (2), with selected lanthanides like lanthanum, gadolinium, and ytterbium. When tested as cytotoxic compounds, such complexes exhibited an activity that was either higher or equal to that of the parent naphthoquinone.

Complexes of Lapachol and Lawsone with Lanthanides

Naturally occurring 2-hydroxy-1,4-naphthoquinones are well known to form readily stable complexes with transition metals. In this short communication we describe for the first time the synthesis and preliminary data about structural characterization of complexes between two naturally widespread 2-hydroxy-1,4-naphthoquinones, namely lapachol (1) and lawsone (2), with selected lanthanides like lanthanum, gadolinium, and ytterbium. When tested as cytotoxic compounds, such complexes exhibited an activity that was either higher or equal to that of the parent naphthoquinone.

Phytochemistry of the genus Skimmia (Rutaceae)

The genus Skimmia is a rich source of interesting secondary metabolites, including 20 alkaloids derived from anthranilic acid, 45 coumarins, 21 limonoids, four cholestane derivatives, six pentacyclic triterpenes, six flavonoids, and two unusual fatty acid derivatives. Skimmia is employed in folk medicine e.g. against fever, inflammations, and rheumatism. Skimmia extracts, Skimmia essential oils and pure compounds isolated from Skimmia extracts have been experimentally shown to have various bioactivities such as antioxidant, anti-inflammatory, antimicrobial, and insecticidal. In this review we discuss the exact structures of compounds isolated from members of the genus Skimmia, bioactivities of Skimmia extracts and pure compounds derived from them, and systematic implications of the patterns of occurrence of these compounds. Moreover, research gaps and interesting avenues for future research are discussed briefly.

Phytochemistry and Pharmacology of the Genus Tovomita

The genus Tovomita (Fam. Clusiaceae) comprises 45 species mainly found in tropical regions of Central and South America. Most of the species of the title genus have been used for centuries as natural remedies. Phytochemicals isolated from Tovomita spp. include prenylated and unprenylated benzophenones and xanthones. The aim of this review is to examine in detail from a phytochemical and pharmacological point of view what is reported in the past and current literature about the properties of phytopreparations and individual active principles obtained from plants belonging to the Tovomita genus.

Antibacterial and Anti-inflammatory Activities of Ppc-1, Active Principle of the Cellular Slime Mold Polysphondylium pseudo-candidum

The diisopentenyloxy quinolobactin derivative 3-methylbut-2-enyl-4-methoxy-8-[(3-methylbut-2-enyl)oxy] quinoline-2-carboxylate, also named as Ppc-1, has been initially isolated from the fruiting bodies of the cellular slime mold Polysphondylium pseudo-candidum. Given that few data are available in the literature concerning the biological properties of this compound, this study was undertaken to evaluate its antibacterial and anti-inflammatory properties. Ppc-1 exerted antibacterial activity on the Gram negative periodontopathogen Porphyromonas gingivalis, while it had no such effect on the other bacterial species tested. The antibacterial activity of Ppc-1 appeared to result from its ability to permeate the cell membrane. Using the U937-3xκB-LUC human monocytic cell line, Ppc-1 was found to dose-dependently inhibit the lipopolysaccharide-induced NF-κB activation, a signaling pathway that has been associated with inflammatory mediator secretion. In conclusion, Ppc-1, by exhibiting a dual mode of action including antibacterial and anti-inflammatory activities, may represent a promising targeted therapeutic agent for periodontal diseases.

Inhibition of soybean 15-lipoxygenase by naturally occurring acetophenones and derricidin

Three selected naturally occurring oxyprenylated secondary metabolites, namely 2-hydroxy4-isopentenyloxyacetophenone (1), 4-geranyloxy-2-hydroxyacetophenone (2), 4-farnesyloxyacetophenone (3), and derricidin (4) were synthesized and their inhibitory potency against soybean 15-lipoxygenase evaluated. Compounds 1 and 4 showed the most potent inhibitory activity with ICo50 values of 2.5 µM and 0.6 µM.

Inhibition of Soybean 15-Lipoxygenase by Naturally Occurring Acetophenones and Derricidin

Three selected naturally occurring oxyprenylated secondary metabolites, namely 2-hydroxy4-isopentenyloxyacetophenone (1), 4-geranyloxy-2-hydroxyacetophenone (2), 4-farnesyloxyacetophenone (3), and derricidin (4) were synthesized and their inhibitory potency against soybean 15-lipoxygenase evaluated. Compounds 1 and 4 showed the most potent inhibitory activity with IC50 values of 2.5 μM and 0.6 μM.

Screening for novel plant sources of prenyloxyanthraquinones: Senna alexandrina Mill. and Aloe vera (L.) Burm. F

As a continuation of our ongoing studies aimed to reveal the presence of oxyprenylated anthraquinones in plants claimed to have a laxative effect, in this article, we describe the extraction and HPLC separation of madagascin (3-isopentenyloxyemodin) and 3-geranyloxyemodine from dried leaves and fruits of Senna alexandrina Mill. (Leguminosae) and leaves and gel of Aloe vera (L.) Burm. F. (Xanthorrhoeaceae). Both compounds are described herein for the first time as components of extracts of the title plants.

Analysis of biologically active oxyprenylated ferulic acid derivatives in Citrus fruits

4'-Geranyloxyferulic (GOFA) and boropinic acid have been discovered during the last decade as interesting phytochemicals having valuable pharmacological effects as cancer chemopreventive, anti-inflammatory, neuroprotective, and anti-Helicobacter pylori agents. A reverse-phase HPLC-UV/Vis method for the separation and quantification of the title oxyprenylated ferulic acid derivatives in extracts obtained from peels of nine edible Citrus and Fortunella fruits was successfully applied. Concentration values showed a great variation between the different species, being orange (C. sinensis) the fruit richest in GOFA (0.141 ± 0.011 mg/g of exocarp fresh weight) and kumquat (Fortunella japonica) the one in which boropinic acid was recorded as the most abundant phytochemical (0.206 ± 0.002 mg/g of exocarp fresh weight). Both secondary metabolites were not detected only in three species. The set-up methodology showed limits of quantification (LOQ) values, that were able to selectively quantify both GOFA and boropinic acid. Results described herein depict a potential chemopreventive dietary feeding role for the Rutaceae spp. under investigation.

Antibacterial activities of oxyprenylated chalcones and napthtoquinone against Helicobacter pylori

In this study, we synthesized and characterized the antibacterial activity of three naturally occurring oxyprenylated chalcones {xinjiachalcone A (1), (2E)-1-{2,6-dihydroxy-4-[(3-methylbut-2-enyl)oxy]phenyl}-3-(4-hydroxyphenyl)prop-2-en-1-one (2), (2E)-1-{2,6-dihydroxy-4-[(3-methylbut-2-enyl)oxy]phenyl}-3-phenylprop-2-en-1-one (3), and lawsone 2-isopentenyl ether (4)}. Using several strains of Helicobacter pylori, including clinical ones, minimum inhibitory concentration (MIC) values and bactericidal activities of these compounds were determined. Xinjiachalcone A (1), active principle of Glycyrrhiza inflata Batalin, was the most effective compound, showing both a low MIC and a strong bactericidal activity against H. pylori. This study suggests that these compounds represent potential natural molecules for the prevention and treatment of H. pylori associated diseases.

Antibacterial Activities of Oxyprenylated Chalcones and Napthtoquinone against Helicobacter pylori

In this study, we synthesized and characterized the antibacterial activity of three naturally occurring oxyprenylated chalcones {xinjiachalcone A (1), (2 E)-1-{2,6-dihydroxy-4-[(3-methylbut-2-enyl)oxy]phenyl}-3-(4-hydroxyphenyl)prop-2-en-1-one (2), (2 E)-1-{2,6-dihydroxy-4-[(3-methylbut-2-enyl)oxy]phenyl}-3-phenylprop-2-en-1-one (3), and lawsone 2-isopentenyl ether (4)}. Using several strains of Helicobacter pylori, including clinical ones, minimum inhibitory concentration (MIC) values and bactericidal activities of these compounds were determined. Xinjiachalcone A (1), active principle of Glycyrrhiza inflata Batalin, was the most effective compound, showing both a low MIC and a strong bactericidal activity against H. pylori. This study suggests that these compounds represent potential natural molecules for the prevention and treatment of H. pylori associated diseases.