Boron compounds with group VI elements: properties of boron-oxygen compounds: B6O, B12O2, B7O

The ability of bismuth to maneuver between different oxidation states in a catalytic redox cycle, mimicking the canonical organometallic steps associated to a transition metal, is an elusive and unprecedented approach in the field of homogeneous catalysis. Herein we present a catalytic protocol based on bismuth, a benign and sustainable main-group element, capable of performing every organometallic step in the context of oxidative fluorination of boron compounds; a territory reserved to transition metals. A rational ligand design featuring hypervalent coordination together with a mechanistic understanding of the fundamental steps, permitted a catalytic fluorination protocol based on a Bi(III)/Bi(V) redox couple, which represents a unique example where a main-group element is capable of outperforming its transition metal counterparts.<br>A main text and supplementary material have been attached as pdf files containing all the methodology, techniques and characterization of the compounds reported.<br>

Effects ofS-nitroso-N-acetylcysteine on contractile function of reperfused skeletal muscle

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1998.274.3.r822 ◽

1998 ◽

Vol 274 (3) ◽

pp. R822-R829 ◽

Cited By ~ 8

Author(s):

Long-En Chen ◽

Anthony V. Seaber ◽

Rima M. Nasser ◽

Jonathan S. Stamler ◽

James R. Urbaniak

Keyword(s):

Skeletal Muscle ◽

Reperfusion Injury ◽

Contractile Function ◽

Ischemia Reperfusion ◽

Protective Role ◽

Control Group ◽

Group Vi ◽

No Donor ◽

Early Reperfusion ◽

Reconstructive Operations

The ultimate goal of replantation and microsurgical reconstructive operations is to regain or improve impaired function of the tissue. However, the data related to the influence of NO on tissue function are limited. This study evaluated the effects of the NO donor S-nitroso- N-acetylcysteine (SNAC) on contractile function of skeletal muscle during reperfusion. Forty-nine rats were divided into six groups. The extensor digitorum longus (EDL) muscles in groups I and II were not subjected to ischemia-reperfusion but were treated with a low (100 nmol/min) or high (1 μmol/min) dose of SNAC. In groups III- V, the EDL underwent 3 h of ischemia and 3 h of reperfusion and was also treated with low (100 nmol/min) or high doses (1 or 5 μmol/min) of SNAC. Group VI was a phosphate-buffered saline (PBS)-treated control group. Twenty additional animals were used to document systemic effects of SNAC and PBS only. SNAC or PBS was infused for 6.5 h, beginning 30 min before ischemia and continuing throughout the duration of reperfusion. Contractile testing compared the maximal twitch force, isometric tetanic contractile forces, fatigue, and fatigue half time of the experimental EDL and the contralateral nontreated EDL. The findings indicate that 1) SNAC does not influence contractile function of EDL muscle not subjected to ischemia-reperfusion, 2) SNAC significantly protects the contractile function of ischemic skeletal muscle against reperfusion injury in the early reperfusion period, and 3) the protective role of SNAC is critically dosage dependent; protection is lost at higher doses. The conclusion from this study is that supplementation with exogenous NO exerts a protective effect on the tissue against reperfusion injury.

Synthesis and Characterisation of a Boron-Rich Symmetric Triazine Bearing a Hypoxia-Targeting Nitroimidazole Moiety

Symmetry ◽

10.3390/sym13020202 ◽

2021 ◽

Vol 13 (2) ◽

pp. 202

Author(s):

Tobias Hartwig Bünning ◽

Luigi Panza ◽

Abdel Kareem Azab ◽

Barbara Muz ◽

Silvia Fallarini ◽

...

Keyword(s):

Tumor Tissue ◽

High Ratio ◽

Neutron Capture Therapy ◽

Boron Compounds ◽

The Core ◽

Boron Neutron Capture ◽

Starting Point ◽

Primary Fibroblasts ◽

Normal Human ◽

Hypoxia Markers

Boron Neutron Capture Therapy (BNCT) is a binary therapy that promises to be suitable in treating many non-curable cancers. To that, the discovery of new boron compounds able to accumulate selectively in the tumour tissue is still required. Hypoxia, a deficiency of oxygen in tumor tissue, is a great challenge in the conventional treatment of cancer, because hypoxic areas are resistant to conventional anticancer treatments. 2-Nitroimidazole derivatives are known to be hypoxia markers due to their enrichment by bioreduction in hypoxic cells. In the present work, 2-nitroimidazole was chosen as the starting point for the synthesis of a new boron-containing compound based on a 1,3,5-triazine skeleton. Two o-carborane moieties were inserted to achieve a high ratio of boron on the molecular weight, exploiting a short PEG spacer to enhance the polarity of the compound and outdistance the active part from the core. The compound showed no toxicity on normal human primary fibroblasts, while it showed noteworthy toxicity in multiple myeloma cells together with a consistent intracellular boron accumulation.