Two New Retigerane-Type Sesterterpenoids from the Lichen Leprocaulon microscopicum

International audienceTwo new sesterterpenes, 1 and 2, have been isolated from the lichen Leprocaulon microscopicum. In addition to classic chromatographic methods, a liquid-liquid chromatography technique, namely centrifugal partition chromatography (CPC) was applied for the purification of compound 2. The structures were determined by analyses of mass spectrometry and 1D- and 2D-NMR data. The relative configuration of the isolated compounds was assigned on the basis of 2D-NOESY experiments. The two compounds possess a rare pentacyclic carbon skeleton typical for lichen metabolism, and quite unusual in the vegetal kingdom

Design and synthesis of triphenylphosphonium-porphyrin@xylan nanoparticles for anticancer photodynamic therapy

Most photosensitizers (PS) suffer from a lack of water solubility and from a low selectivity toward tumor cells. Delivery systems using nanoparticles make it possible to improve PS water solubility, and also tumor targeting via the enhanced permeability and retention (EPR) effect. Among the organelles, mitochondria are attractive target sites for drug-delivery strategies since they perform a variety of key cellular processes. Our study was aimed at synthesizing nanoparticles consisting of xylan-carrying porphyrins attached to a triphenylphosphonium moiety, in order to enhance the PDT effect through mitochondrial targeting. Hybrid nanoparticles were designed that consisted of a silica core coated with xylan substituted with porphyrin derivatives carrying a triphenylphosphonium moiety. These hybrid nanoparticles have been constructed, along with their counterparts devoid of silica core, taking into consideration the controversy surrounding the use of silica nanoparticles. Phototoxicity experiments, conducted against the HCT-116 and HT-29 colorectal cancer cell lines, showed that nanoparticles with porphyrins bearing a triphenylphosphonium moiety exhibited an enhanced photocytotoxic effect in comparison with free porphyrin or nanoparticles with porphyrins without the triphenylphosphonium moiety

Design and synthesis of triphenylphosphonium-porphyrin@xylan nanoparticles for anticancer photodynamic therapy

Most photosensitizers (PS) suffer from a lack of water solubility and from a low selectivity toward tumor cells. Delivery systems using nanoparticles make it possible to improve PS water solubility, and also tumor targeting via the enhanced permeability and retention (EPR) effect. Among the organelles, mitochondria are attractive target sites for drug-delivery strategies since they perform a variety of key cellular processes. Our study was aimed at synthesizing nanoparticles consisting of xylan-carrying porphyrins attached to a triphenylphosphonium moiety, in order to enhance the PDT effect through mitochondrial targeting. Hybrid nanoparticles were designed that consisted of a silica core coated with xylan substituted with porphyrin derivatives carrying a triphenylphosphonium moiety. These hybrid nanoparticles have been constructed, along with their counterparts devoid of silica core, taking into consideration the controversy surrounding the use of silica nanoparticles. Phototoxicity experiments, conducted against the HCT-116 and HT-29 colorectal cancer cell lines, showed that nanoparticles with porphyrins bearing a triphenylphosphonium moiety exhibited an enhanced photocytotoxic effect in comparison with free porphyrin or nanoparticles with porphyrins without the triphenylphosphonium moiety

Comparative characterization of phenolic and other polar compounds in Spanish melon cultivars by using high-performance liquid chromatography coupled to electrospray ionization quadrupole-time of flight mass spectrometry

Melon (Cucumis melo L.), belonging to the Cucurbitaceae family, is a significant source of phytochemicals which provide human health benefits. High-performance liquid chromatography coupled to electrospray ionization mass spectrometry quadropole-time of flight (HPLC-ESIQTOF-MS) was used for the comprehensive characterization of 14 extracts from 3 Spanish varieties of melon (Galia, Cantaloupe, and Piel de Sapo). A total of 56 different compounds were tentatively identified, including: amino acids and derivatives, nucleosides, organic acids, phenolic acids and derivatives, esters, flavonoids, lignans, and other polar compounds. Of these, 25 were tentatively characterized for the first time in C. melo varieties. Principalcomponent analysis (PCA) was applied to gain an overview of the distribution of the melon varieties and to clearly separate the different varieties. The result of the PCA for the negative mode was evaluated. The variables most decisive to discriminate among varieties included 12 of the metabolites tentatively identified.CIDAF (Centro de Investigación y desarrollo del Alimento Funcional), Departamento de química analítica. Grupo FQM-297

Bioactive Constituents of Juniperus turbinata Gussone from La Maddalena Archipelago

A comprehensive phytochemical study of Juniperus turbinata (Cupressaceae) collected from La Maddalena Archipelago (Sardinia, Italy) is reported. Both the essential oil and the ethanolic extract obtained from the aerial parts were analyzed. The essential oil appears to belong to a new chemotype compared to other Mediterranean juniper accessions, as it was favored by geographic isolation of the isles. It showed a low content of monoterpene hydrocarbons and a-terpineol, entmanoyl oxide, 1,10-di-epi-cubenol as the major constituents. The ethanolic fraction contained mainly diterpenoids. Among these, 15-formyloxyimbricatolic acid (7) is a new natural product since it has hitherto been obtained only by synthetic route. The phenolic fraction contained biflavonoids: cupressuflavone (9), followed by minor amounts of amentoflavone (10) and hinokiflavone (11). The essential oil and six purified compounds (1 – 4, 8 and 9) were assessed for biological activities, namely antioxidant (assessed by DPPH·, ABTS· + and FRAP methods) and cytotoxic effects towards selected human tumor cell lines (MDA-MB 231, A375 and HCT116 cells). Compound 3 exhibited higher radical scavenging activity against ABTS·+ radical than the reference Trolox. Noteworthy, compound 8 showed powerful effects towards tumor cell lines, with IC50 values in the range of 0.060 – 0.201 lM, which make it a promising anticancer drug candidate

Tannins, Peptic Ulcers and Related Mechanisms

This review of the current literature aims to study correlations between the chemical structure and gastric anti-ulcer activity of tannins. Tannins are used in medicine primarily because of their astringent properties. These properties are due to the fact that tannins react with the tissue proteins with which they come into contact. In gastric ulcers, this tannin-protein complex layer protects the stomach by promoting greater resistance to chemical and mechanical injury or irritation. Moreover, in several experimental models of gastric ulcer, tannins have been shown to present antioxidant activity, promote tissue repair, exhibit anti Helicobacter pylori effects, and they are involved in gastrointestinal tract anti-inflammatory processes. The presence of tannins explains the anti-ulcer effects of many natural products

Development of a vibration monitoring strategy based on cyclostationary analysis for the predictive maintenance of helicopter gearbox bearings

The scope of this paper is the development of a fault detection and diagnosis method aimed to helicopter gearbox bearings vibration monitoring in an operational context. Bearings are critical components in the gearbox, and their monitoring allows for failure anticipation capabilities, leading to increased safety and improved maintenance planning. Deploying a monitoring strategy for helicopter gearboxes necessitates the development of a methodology which can provide reliable information under varying operating conditions, dealing with a noisy vibration environment and simultaneously considering acquisition system constraints, such as limited acquisition duration and sampling frequency, and operational needs, such as low rate of false alarms and minimal workload for the analyst. The approach proposed in this paper is based on the cyclostationary signals theory and relies on a two-steps procedure of detection and diagnosis. First, bearing fault detection indicators are devised on a statistical basis, leveraging on the theoretical properties of the envelope method. Then, a diagnosis based on the computation of the averaged cyclic periodogram is performed to assess the damage in the eventuality of an alarm. The developed methodology is validated on real helicopter data collected over about twenty thousand f light hours, including four bearings from different machines for which in-service spalling initiation occurred. The fault detection performance is evaluated on the basis of the achieved false alarm rates and the improvement in fault anticipation with respect to chip detectors, whereas the capability of isolating the fault-related signals using cyclostationary signal separation methods is shown for the diagnosis stage

Design of a new oligotriazole peptide nucleic acid analogue (oT-PNA)

International audienceWe describe in this Letter the synthesis of an original thymine azido-heterotrimer generated by Click Chemistry. This trimer has been obtained from an azido-thymidine and a new chloroethyl-propargylated PNA monomer analogue, after two azidation/click-reaction cycles. Conformational preferences of a rotameric intermediate have also been studied