The sesquiterpenes β-caryophyllene and caryophyllene oxide isolated from Senecio salignus act as phytogrowth and photosynthesis inhibitors

The n-hexane extract of S. salignus plants inhibited ATP synthesis and two sesquiterpenes, the β-caryophyllene (1) and caryophyllene oxide (2) were isolated from this nonpolar fraction. Compound 1 inhibited by 42% the root elongation of Physalis ixocarpa seedlings at 50 μg/mL and by 53% at 150 μg/mL, whereas at 150 μg/mL this compound only inhibited root elongation of Echinochloa crus-galli by 30%. On the other hand, compound 2 had no effect on either germination or root and stem growth of E. cruss galli and P. ixocarpa. However, 1 and 2 inhibited the dry biomass of P. ixocarpa plants grown for 18 days previous to treatment and it was found that 1 was the most active biomass inhibitor. The Chl a fluorescence transient in vivo experiment indicates that 1 (100 μg/mL) has a major effect at 72 h after treatment on leaves of P. ixocarpa plants by inhibiting photosystem II (PS II) transforming active reaction centers to "heat sinks" or the formation of silent reaction centers unable to reduce Q(A). β-Caryophyllene also induces chlorosis on treated leaves.     

Skin permeation of cacalol, cacalone and 6-epi-cacalone sesquiterpenes from a nanoemulsion

The objective of the present study was to investigate the transdermal permeation of cacalol (1) and a mixture of cacalone (2) and 6-epi-cacalone (3) in comparison with diclofenac acid (4) delivered from the same characterized nanoemulsion using Franz diffusion cells (formulae I, II and III). Results show that de Kp, J, Q24, PI and P2 were higher for the acid diclofenac nanoemulsion than for the natural products nanoemulsions. As for the differences between the formulations I and II, with the natural products, Q24, the quantity extracted from skin and P2 were higher in the mixture of 2 and 3 nanoemulsion compared with the corresponding nanoemulsion of 1. In conclusion, the low permeability of the natural products nanoemulsions in comparison with that of diclofenac acid has the potential for development for drugs with local and systemic applications, respectively.     

Probing the relationships between molecular conformation and intermolecular contacts in N,N‐dibenzyl‐N′‐(furan‐2‐carbonyl)thiourea

In the crystal structure of the title compound, C₂₀H₁₈N₂O₂S, molecules are linked by bifurcated C—H...O hydrogen‐bond interactions, giving rise to chains whose links are composed of alternating centrosymmetrically disposed pairs of molecules and characterized by R₂²(10) and R₂²(20) hydrogen‐bonding motifs. Also, N—H...S hydrogen bonds form infinite zigzag chains along the [010] direction, which exhibit the C(4) motif. Hirshfeld surface and fingerprint plots were used to explore the intermolecular interactions in the crystal structure. This analysis confirms the important role of C—H...O hydrogen bonds in the molecular conformation and in the crystal structure, providing a potentially useful tool for a full understanding of the intermolecular interactions in acylthiourea derivatives.     

The dependence of α-tocopheroxyl radical reduction by hydroxy-2,3-diarylxanthones on structure and micro-environment

The flavonoid quercetin is known to reduce the α-tocopheroxyl radical (˙TocO) and reconstitute α-tocopherol (TocOH). Structurally related polyphenolic compounds, hydroxy-2,3-diarylxanthones (XH), exhibit antioxidant activity which exceeds that of quercetin in biological systems. In the present study repair of ˙TocO by a series of these XH has been evaluated using pulse radiolysis. It has been shown that, among the studied XH, only 2,3-bis(3,4-dihydroxyphenyl)-9H-xanthen-9-one (XH9) reduces ˙TocO, though repair depends strongly on the micro-environment. In cationic cetyltrimethylammonium bromide (CTAB) micelles, 30% of ˙TocO radicals are repaired at a rate constant of ~7.4 × 10(6) M(-1) s(-1) by XH9 compared to 1.7 × 10(7) M(-1) s(-1) by ascorbate. Water-soluble Trolox (TrOH) radicals (˙TrO) are restored by XH9 in CTAB (rate constant ~3 × 10(4) M(-1) s(-1)) but not in neutral TX100 micelles where only 15% of ˙TocO are repaired (rate constant ~4.5 × 10(5) M(-1) s(-1)). In basic aqueous solutions ˙TrO is readily reduced by deprotonated XH9 species leading to ionized XH9 radical species (radical pK(a) ~10). An equilibrium is observed (K = 130) yielding an estimate of 130 mV for the reduction potential of the [˙X9,H(+)/XH9] couple at pH 11, lower than the 250 mV for the [˙TrO,H(+)/TrOH] couple. A comparable value (100 mV) has been determined by cyclic voltammetry measurements.     

Towards β-selectivity in functional estrogen receptor antagonists

Based on the benzo[b]naphtho[1,2-d]furan and benzo[b]naphtho[1,2-d]thiophene frameworks, a series of ligands with different basic side chains (BSCs) has been synthesized and pharmacologically evaluated. Also, their binding modes have been modelled using docking techniques. It was found that the introduction of a BSC in these systems brings about a decrease of affinity for both estrogen receptors α and β in an in vitro competitive binding assay. However, two full antagonists of the estrogen receptor β ( and ) have been discovered, with potency in the low micromolar concentration in a cell-based luciferase reporter assay, and completely devoid of activity against the α receptor at the same concentration range. Differences in the ERα/ERβ binding modes have also been rationalized with the help of molecular modelling techniques. This interesting functional profile could be used to elucidate the physiological role of each ER subtype.     

A bisphosphonite calix[5]arene ligand that stabilizes η6 arene coordination to palladium

Treatment of a bis(phenylphosphonite)calix[5]arene ligand with either palladium(II) chloride or 1,5-cyclooctadieneplatinum(II) chloride yields square planar metal complexes in which the two phosphorus atoms bind cis to the MCl(2) moiety (M = Pd, Pt). Chloride was removed from the palladium complex to open a coordination site at the metal for catalysis. The chloride removal resulted in a rare and unexpected η(6) coordination of an arene to the metal. The reaction is reversible upon addition of tetra-n-butyl ammonium chloride.     

Evaluation of stationary phases and gas chromatographic detectors for determination of amines in water

For the first time, a systematic overview deals with the advantages and disadvantages of several stationary phases (polar and non‐polar) and gas chromatographic detectors (flame ionization detector, nitrogen–phosphorus detector and MS) for the determination of 27 amines (aliphatic and aromatic amines and N‐nitrosamines) in water samples. To increase sensitivity (250 mL of sample was eluted with 150 μL of solvent) and matrix elimination, an automatic SPE system was employed prior to GC determination. The best results in terms of resolution and retention times were achieved using a column coated with 5% phenyl‐dimethylpolysiloxane (DB‐5). Capacity factor (k) values for the 27 amines increased with the rise in the polarity of the stationary phase, ranging from 3.0–27.7 and 2.2–14.4 for polar (polyethylene glycol) and non‐polar (DB‐5) columns, respectively. The detection limits of the method were 0.9–9 μg/L for flame ionization detector, 8–95 ng/L for nitrogen–phosphorus detector and 0.2–6.3 ng/L for MS. The precision was similar for the three detectors (RSD, 3.7–6.0%). The GC‐MS method was applied with a high degree of accuracy and precision to determine amines in real samples including tap, river, pond, well, swimming pool and wastewaters.     

Influence of gamma radiation onto polymeric matrix with papain

Papain is a proteolytic enzyme that has been widely used as debridement agent for scars and wound healing treatment. However, papain presents low stability, which limits its use to extemporaneous or short shelf-life formulations. The purpose of this study was to entrap papain into a polymeric matrix in order to obtain a drug delivery system that could be used as medical device. Since these systems must be sterile, gamma radiation is an interesting option and presents advantages in relation to conventional agents: no radioactive residues are formed; the product can be sterilized inside the final packaging and has an excellent reliability. The normative reference for the establishment of the sterilizing dose determines 25 kGy as the inactivation dose for viable microorganisms. A silicone dispersion was selected to prepare membranes containing 2% (w/w) papain. Irradiated and non-irradiated membranes were simultaneously assessed in order to verify whether gamma radiation interferes with the drug-releasing profile. Results showed that irradiation does not affect significantly papain release and its activity. Therefore papain shows radioresistance in the irradiation conditions applied. In conclusion, gamma radiation can be easily used as sterilizing agent without affecting the papain release profile and its activity onto the biocompatible device is studied.     

Studies of C<Subscript>8</Subscript> aromatics adsorption in BaY and mordenite molecular sieves using the headspace technique

A headspace technique, that consists in analyzing the composition of the vapor phase in equilibrium with the condensed phase of a mixture in a sealed vial containing the adsorbent sample, has been recently applied to acquire equilibrium data for adsorption of xylenes in liquid phase. In this study, we used this technique to measure experimental binary equilibrium data for C₈ aromatics in Y and mordenite zeolitic molecular sieves. For the Y zeolite, we also measured C₈ aromatics quaternary equilibrium data. Measurements were made at temperatures between C 40–80 °C. A more tedious, but traditional, chromatographic pulses method was also used to validate some of the results.     

Cyclization of Zincated α‐N‐Homoallylamino Nitriles: A New Entry to Enantiopure 2,3‐Methanopyrrolidines

Stereoselective cyclization of zincated α‐N‐homoallylamino nitriles has been developed. Following treatment with lithium diisopropylamide (LDA) and transmetalation with zinc bromide, α‐N‐(1‐phenylethyl)‐N‐homoallylamino nitriles lead to 2,3‐methanopyrrolidines in moderate to good yields (up to 66 %) and excellent selectivities (up to >98:2). With substrates derived from α‐branched homoallylic amines, a stereospecific inversion of the homoallylic stereogenic center was observed. To account for this, a mechanistic rationale involving the formation of zincioiminium ions from zincated α‐amino nitriles is put forward. 2,3‐Methanopyrrolidines should then arise from a sequence involving an aza‐Cope rearrangement providing a configurationally stable (2‐azoniaallyl)zinc species that then undergoes a [3+2] cycloaddition reaction.