Prospects of Curcumin Nanoformulations in Cancer Management

There is increasing interest in the use of natural compounds with beneficial pharmacological effects for managing diseases. Curcumin (CUR) is a phytochemical that is reportedly effective against some cancers through its ability to regulate signaling pathways and protein expression in cancer development and progression. Unfortunately, its use is limited due to its hydrophobicity, low bioavailability, chemical instability, photodegradation, and fast metabolism. Nanoparticles (NPs) are drug delivery systems that can increase the bioavailability of hydrophobic drugs and improve drug targeting to cancer cells via different mechanisms and formulation techniques. In this review, we have discussed various CUR-NPs that have been evaluated for their potential use in treating cancers. Formulations reviewed include lipid, gold, zinc oxide, magnetic, polymeric, and silica NPs, as well as micelles, dendrimers, nanogels, cyclodextrin complexes, and liposomes, with an emphasis on their formulation and characteristics. CUR incorporation into the NPs enhanced its pharmaceutical and therapeutic significance with respect to solubility, absorption, bioavailability, stability, plasma half-life, targeted delivery, and anticancer effect. Our review shows that several CUR-NPs have promising anticancer activity; however, clinical reports on them are limited. We believe that clinical trials must be conducted on CUR-NPs to ensure their effective translation into clinical applications.     

Fine‐Tuning of Lewis Acidity: The Case of Borenium Hydride Complexes Derived from Bis(phosphinimino)amide Boron Precursors

Reactions of bis(phosphinimino)amines LH and L′H with Me₂S ? BH₂Cl afforded chloroborane complexes LBHCl ( 1 ) and L′BHCl ( 2 ), and the reaction of L′H with BH₃ ? Me₂S gave a dihydridoborane complex L′BH₂ ( 3 ) (LH=[{(2,4,6‐Me₃C₆H₂N)P(Ph₂)}₂N]H and L′H=[{(2,6‐iPr₂C₆H₃N)P(Ph₂)}₂N]H). Furthermore, abstraction of a hydride ion from L′BH₂ ( 3 ) and LBH₂ ( 4 ) mediated by Lewis acid B(C₆F₅)₃ or the weakly coordinating ion pair [Ph₃C][B(C₆F₅)₄] smoothly yielded a series of borenium hydride cations: [L′BH]⁺[HB(C₆F₅)₃]^? ( 5 ), [L′BH]⁺[B(C₆F₅)₄]^? ( 6 ), [LBH]⁺[HB(C₆F₅)₃]^? ( 7 ), and [LBH]⁺[B(C₆F₅)₄]^? ( 8 ). Synthesis of a chloroborenium species [LBCl]⁺[BCl₄]^? ( 9 ) without involvement of a weakly coordinating anion was also demonstrated from a reaction of LBH₂ ( 4 ) with three equivalents of BCl₃. It is clear from this study that the sterically bulky strong donor bis(phosphinimino)amide ligand plays a crucial role in facilitating the synthesis and stabilization of these three‐coordinated cationic species of boron. Therefore, the present synthetic approach is not dependent on the requirement of weakly coordinating anions; even simple BCl₄^? can act as a counteranion with borenium cations. The high Lewis acidity of the boron atom in complex 8 enables the formation of an adduct with 4‐dimethylaminopyridine (DMAP), [LBH ? (DMAP)]⁺[B(C₆F₅)₄]^? ( 10 ). The solid‐state structures of complexes 1 , 5 , and 9 were investigated by means of single‐crystal X‐ray structural analysis.     

Molecular variability of lignin fractions isolated from wheat straw

Three lignin fractions were isolated from wheat straw internodes and leaves: alkali lignin (LA), milled lignin (LM) and enzyme lignin (LE). Thioacidolysis and alkaline nitrobenzene oxidation were used for the characterisation of the lignin monomeric composition. Esterified and etherifiedp-coumaric and ferulic acids were characterised by alkali hydrolysis and acidolysis, respectively. Lignin fractions from leaves are more condensed than those from internodes. The syringyl/guaiacyl (S/G) ratio is higher in the case of internode lignins. Among the three lignin fractions, LA is the less condensed whereas LM and LE do not present significant structural differences according to their monomeric composition. Finally, the lignin fractions studied differ in their contents and proportions of associated phenolic acids.     

Symmetrical carbazole–fluorene–carbazole nematic liquid crystals as electroluminescent organic semiconductors

A series of novel symmetrical carbazole–fluorene–carbazoles has been synthesised using simple and highly efficient reaction pathways. The correlation between their molecular structures, differing in the length of the alkyl chains in the lateral position attached to a 2,7-disubstituted fluorene moiety in the molecular core and/or differing in the length of alkoxy chains at the terminal positions of 2,7-disubstituted carbazole moieties, was investigated. Their mesomorphic behaviour, transition temperatures, energy levels and band gaps were measured. A test organic light-emitting diode incorporating one of these compounds exhibits blue electroluminescence.     

Liquid crystalline organic semiconductors: nematic spiro[cyclopentyl-1,9′]fluorenes

A number of nematic spiro[cyclopentyl-1,9′]fluorene reactive mesogens with polymerisable oxetane or non-conjugated diene end-groups have been successfully synthesised. The melting and clearing points of these new spiro[cyclopentyl-1,9′]fluorenes are much higher than those of the corresponding 9,9-diethyl- or 9,9-dipropyl-substituted fluorenes, which are present in many light-emitting polymers currently used in polymer light-emitting diodes. The significant difference in transition temperature may be attributed to the lower intermolecular separation induced by the more rigid and less bulky cyclopentyl group, confirmed by molecular modelling. The presence of either these short but flexible aliphatic chains, or a rigid alicyclic group of similar size and shape, results in only small differences in the photoluminescence spectra and efficiency of these model liquid crystalline organic semiconductors, and in their improved thermal stability.     

Two Different Pathways in the Reduction of [(S=)PCl(μ‐NtBu)]2 with Na

Reduction of the cyclodiphosphazane [(S=)ClP(μ‐NtBu)]₂ ( 1 ) with sodium metal in refluxing toluene proceeds via two different pathways. One is a Wurtz‐type pathway involving elimination of NaCl from 1 followed by head‐to‐tail cyclization to give the hexameric macrocycle [(μ‐S)P(μ‐NtBu)₂P(=S)]₆ ( 2 ). The other pathway involves reduction of the P=S bonds of 1 to generate colorless singlet biradicaloid dianion trans‐[S?P(Cl)(μ‐NtBu)]₂^2?, which is observed in the polymeric structures of three‐dimensional [{(S?)ClP(μ‐NtBu)₂PCl(S)}Na(Na ? THF₂)]_n ( 3 ) and two dimensional [{(S?)ClP(μ‐NtBu)₂PCl(S)} (Na ? THF)₂]_n ( 4 ).