Metformin is a widely used biguanide drug due to its safety and low cost. It has been used for over 60 years to treat type 2 diabetes at the early stages because of its outstanding ability to decrease plasma glucose levels. Over time, different uses of metformin were discovered, and the benefits of metformin for various diseases and even aging were verified. These diseases include cancers (e.g., breast cancer, endometrial cancer, bone cancer, colorectal cancer, and melanoma), obesity, liver diseases, cardiovascular disease, and renal diseases. Metformin exerts different effects through different signaling pathways. However, the underlying mechanisms of these different benefits remain to be elucidated. The aim of this review is to provide a brief summary of the benefits of metformin and to discuss the possible underlying mechanisms.
In this work, we reported on the advantages of immobilized carbon nanotubes as a novel MALDI-matrix. Recently, carbon nanotubes have been reported to be an effective MALDI matrix for small molecules (Anal. Chem. 2003, 75, 6191), as it can eliminate the interfering matrix peaks as well as form a web morphology to fully disperse the analyte and allow strong ultraviolet absorption for enhanced pulsed laser desorption and ionization. In our study, to overcome the problem that the carbon nanotube matrix may fly off from the target, a type of polyurethane adhesive, NIPPOLAN-DC-205, is introduced to immobilize carbon nanotubes on the target, which enables widespread application of carbon nanotubes as matrix for MALDI-MS analysis. At the same time, the properties of the carbon nanotubes as an efficient matrix remained after immobilization. The presence of NIPPO-LAN-DC-205 increases the time for analysis at a particular desorption spot by minimizing the time-consuming search for "hot spots" and facilitating experiments such as post source decay (PSD) which need longer-lasting signals. Moreover, NIPPOLAN-DC-205 produces no interference peaks and can easily be cleaned with acetone. Fast evaporation technology may be used to enhance signal reproducibility in MALDI analysis using carbon nanotubes as matrix. Consequently, the applicability of the carbon nanotube as matrix for matrixassisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of low molecular mass analytes is highly improved. The feasibility of the method employing polyurethane is demonstrated by comparison of the results produced from the carbon nanotube matrix with and without immobilization. In addition, neutral small carbohydrates, which are difficult to be ionized normally, can be cationized with high efficiency by MALDI-TOF-MS using the immobilized carbon nanotube matrix. The method was further applied to analyze peptides and detect urine glucose successfully. (J Am Soc Mass Spectrom 2005, 16, 333-339)
A palladium-catalyzed intramolecular oxidative aryltrifluoromethylation reaction of activated alkenes has been explored. The reaction allows for an efficient synthesis of a variety of CF(3)-containing oxindoles. Preliminary mechanistic study indicated that the reaction involves a C(sp(3))-Pd(IV)(CF(3)) intermediate, which undergoes reductive elimination to afford a C(sp(3))-CF(3) bond.
A novel palladium-catalyzed intermolecular aminofluorination of styrenes, with N-fluorobenzenesulfonimide (NFSI) functioning not only as a fluorinating reagent but also as an aminating reagent, has been developed. The reaction afforded vicinal fluoroamine products with very high regioselectivity. This transformation may involve fluoropalladation of styrene as a key step for C-F bond formation. The bidental nitrogen ligand is crucial to achieving the transformation successfully.
A robust
and practical protocol for preparing alkyl aryl ethers
has been developed, which relies on using two types of ligands to
promote Cu-catalyzed alkoxylation of (hetero)aryl halides. The reaction
scope is very general for a variety of coupling partners, particularly
for challenging secondary alcohols and (hetero)aryl chlorides. In
case of coupling with aryl chlorides and bromides, two oxalic diamides
serve as the powerful ligands. The tert-butoxide
is first demonstrated as a ligand for Cu-catalyzed coupling reaction,
leading to alkoxylation of aryl iodides complete at room temperature.
Additionally, a number of carbohydrate derivatives are applicable
for this coupling reaction, affording the corresponding carbohydrate-aryl
ethers in 29–98% yields.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.