Application of Vitamin E TPGS in ocular therapeutics – Attributes beyond excipient

Diseases affecting the anterior segment and the external surface of the eye are usually treated by drugs applied topically. The formulations designed for this purpose are developed to deliver active pharmaceutical agents to the eye optimally. These formulations are prepared by adding various agents (excipients) that help to maintain stability of the formulation, prevent microbial contamination, and allow easy administration with adequate drug bioavailability with the minimum ocular irritation and toxic effects at the administration site. The excipients do not have their own pharmacological actions, but Vitamin E TPGS (d-α-Tocopheryl polyethylene glycol 1000 succinate) seems to break this notion. Besides having drug formulation enhancement properties, it also possesses antioxidant properties, which have been found to have a beneficial effect on various ophthalmological diseases such as age-related macular degeneration, uveitis, glaucoma, and cataract. In this review, we primarily focus on the properties and applications of Vitamin E TPGS in ocular drug delivery and the benefits of Vitamin E (Vit E) in numerous sight-threatening ailments of the rear and front segment of the eye. Additionally, p-glycoprotein inhibition and the anti-cancer potential of vitamin E TPGS have also been summarized.     

Organodiphosphines in cis-Pt(η2-P2L)(SR)2 derivatives – structural aspects

Abstract

This review covers 30?Pt(II) complexes in which the inner coordination of PtP₂S₂ is created by organodiphosphines and a pair of S-donor ligands. The organodiphosphines generate four-(PCP), five-(PC₂P), six-(PC₃P) and seven-(PC₄P) membered metallocyclic rings. These complexes crystallize in three crystal systems: orthorhombic (four examples), triclinic (nine examples) and monoclinic (seventeen examples). The respective metallocyclic rings open in the sequence: (mean values): 73.2° (PCP) < 86.0° (PC₂P) < 94.5° (PC₃P) < 97.5° (PC₄P). The mean values of Pt-P and Pt-S bond distances are 2.247 and 2.350?Å, respectively. The structure parameters are analyzed and discussed with attention to any trans-influence.     

Analysis of residual stress profiles in plastic materials using the hole drilling method – Influence factors and practical aspects

The current work introduces a procedure to locally measure residual stresses in polymers. For this purpose, the hole drilling method was adapted to the prevailing boundary conditions. Particular attention is given to the analysis of the measured strain signal which is time dependent and strongly influenced by local temperature fluctuations. The different sources of heat prevailing during the measurement and their impact are outlined. By thorough analysis of the viscoelastic and thermal deformation occurring during and after drilling the material, a procedure is proposed to measure the correct strain relaxation from which residual stresses can be calculated. Using quenched polycarbonate samples with known residual stress profiles, the potential of the proposed approach was demonstrated and is discussed.     

Organodiphosphines in cis-Pt(η2-P2L)(η2-S2L) derivatives – structural aspects

Abstract

In this review structural parameters of forty complexes with an inner coordination sphere of Pt(η²-P₂L)(η²-S₂L) are analyzed and classified These complexes crystallize in three crystal systems: orthorhombic (four examples), triclinic (six examples) and monoclinic (thirty examples). The organodiphosphines create four- (PCP), five- (PC₂P), six- (PC₃P) and seven- (PC₄P) membered metallocyclic rings with mean P-Pt-P bite angle values of 72.5° (PCP) < 85.3° (PC₂P) < 93.0° (PC₃P) < 97.4° (PC₄P). The dithiolates create four- (SCS), five- (SC₂S), six- (SC₃S; SCSCS; SPNPS; SPCPS) and seven- (SC₄S) membered metallocyclic rings with mean S-Pt-S bite angle values of 74.5° (SCS) < 85.8° (SCSCS) < 87.0° (SPNPS) < 89.0° (SC₂S) < 92.3° (SC₄S) < 93.5° (SC₃S) < 97.5° (SPCPS). The mean Pt-P and Pt-S bond distances are 2.257 and 2.328?Å, respectively. The data are compared with those found in complexes with inner coordination spheres of Pt(PL)₂(SL)₂, Pt(PL)₂(η²-S₂L) and Pt(η²-P₂L)(SL)₂.     

NHC-catalysed benzoin condensation – is it all down to the Breslow intermediate?

The Breslow catalytic cycle describing the benzoin condensation promoted by N-heterocyclic carbenes (NHC) as proposed in the late 1950s has since then been tried by generations of physical organic chemists. Emphasis has been laid on proofing the existence of an enaminol like structure (Breslow intermediate) that explains the observed umpolung of an otherwise electrophilic aldehyde. The present study is not focusing on spectroscopic elucidation of a thiazolydene based Breslow intermediate but rather tries to clarify if this key-intermediate is indeed directly linked with the product side of the overall reaction. The here presented EPR-spectroscopic and computational data provide a fundamentally different view on how the benzoin condensation may proceed: a radical pair could be identified as a second key-intermediate that is derived from the Breslow-intermediate via an SET process. These results highlight the close relationship to the Cannizarro reaction and oxidative transformations of aldehydes under NHC catalysis.     

Use of pollution indices and ecological risk in the assessment of contamination from chemical elements in soils and sediments – Practical aspects

This paper presents a discussion involving practical aspects of applying contamination indices and ecological risk factors derived from chemical elements in the environmental assessment of soils and sediments. The single and integrated indices: Geoaccumulation index (I_geo), Enrichment factor (EF), Contamination factor (CF), Pollution Index (PI), Ecological risk factor (E_ir), Pollution Load Index (PLI), Degree of contamination (C_deg), Modified Contamination Factor (mC_deg), and potential ecological risk index (PERI) were discussed, and some applications were presented didactically. The analytical care needed to obtain reliable indices with the studied ecosystem is also evidenced. In addition, the advantages and limitations of the use of these indices are presented.