Stimulation of the energy sensor AMP-activated kinase (AMPK) has been viewed as a targeted approach to increase glucose uptake by skeletal muscle and control blood glucose homeostasis. Rosemary extract (RE) has been reported to activate AMPK in hepatocytes and reduce blood glucose levels in vivo but its effects on skeletal muscle are not known. In the present study, we examined the effects of RE and the mechanism of regulation of glucose uptake in muscle cells. RE stimulated glucose uptake in L6 myotubes in a dose- and time-dependent manner. Maximum stimulation was seen with 5 μg/mL of RE for 4 h (184% ± 5.07% of control, p < 0.001), a response comparable to maximum insulin (207% ± 5.26%, p < 0.001) and metformin (216% ± 8.77%, p < 0.001) stimulation. RE did not affect insulin receptor substrate 1 and Akt phosphorylation but significantly increased AMPK and acetyl-CoA carboxylase phosphorylation. Furthermore, the RE-stimulated glucose uptake was significantly reduced by the AMPK inhibitor compound C, but remained unchanged by the PI3K inhibitor, wortmannin. RE did not affect GLUT4 or GLUT1 glucose transporter translocation in contrast with a significant translocation of both transporters seen with insulin or metformin treatment. Our study is the first to show a direct effect of RE on muscle cell glucose uptake by a mechanism that involves AMPK activation.

A pair of related dinuclear lanthanide compounds, viz., [Dy(tmhd)](bptz) (1) and {CpCo}{[Dy(tmhd)](bptz)} (2) (tmhd = 2,2,6,6-tetramethyl-3,5-heptane dionate; bptz = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine) are reported. These molecules represent the first study of rare earth ions in which an organic ligand bridged species is isolated in both the neutral and radical anion forms. Both compounds exhibit out-of-phase signals below 4 K. The radical compound is highly air stable, with minimal changes in magnetic behavior after exposure to the atmosphere for two weeks.

The first examples of metallacycles containing rare earth ions bridged by radicals are reported. The molecular triangles [Ln(hfac)(bptz)] (Ln = Dy, Y; hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; bptz = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine) consist of lanthanide ions bridged by bptz radical anion (bptz) ligands. Magnetic susceptibility measurements and CASSCF calculations performed on [Dy(hfac)(bptz)] reveal the presence of antiferromagnetic coupling between the Dy centers and the bptz ligands, with J = -6.62 cm.

The first {Mn} cluster (1) has been prepared from carboxylate ions and the chelating/bridging ligand α-methyl-2-pyridine-methanol. Compound 1 possesses a unique nanosized structural topology with one of the largest energy barriers reported to-date for high-nuclearity 3d-metal clusters. Single-crystal magnetic hysteresis studies reveal the presence of hysteresis loops below 5 K, one of the highest temperatures below which molecular hysteresis has been observed for 3d-based SMMs.

The initial employment of 2-(hydroxymethyl)pyridine in 4f metal chemistry has afforded a new family of Ln(III)(9) clusters with a sandglass-like topology and dual physical properties; the Dy(III) member shows single-molecule magnetism behavior, while the Eu(III) analogue exhibits intense red photoluminescence.