Nonalcoholic fatty liver disease (NAFLD) is an abnormal liver metabolism often observed with insulin resistance and metabolic syndrome. Calorie restriction is a useful treatment for NAFLD and reportedly prolongs the life spans of several species in which sirtuin plays an important role. In this study, we examined whether the activation of SIRT1, a mammalian ortholog of sirtuin, may ameliorate the development of NAFLD. Monosodium glutamate (MSG) mice, which exhibited obesity and insulin resistance, were treated with SRT1720, a specific SIRT1 activator from the age of 6-16 wk. Sixteen-week-old MSG mice exhibited increased liver triglyceride content and elevated levels of aminotransferase. SRT1720 treatment significantly reduced these levels without affecting body weight or food intake. These results suggested that the administration of SRT1720 ameliorated the development of NAFLD in MSG mice. The expressions of lipogenic genes, such as sterol regulatory element-binding protein-1c, acetyl-CoA carboxylase, and fatty acid synthase, and the serum lipid profiles, including free fatty acids, were elevated in MSG mice and were reduced by SRT1720 treatment. SRT1720 treatment also reduced the expressions of lipogenic genes in cultured HepG2 cells. Furthermore, SRT1720 treatment decreased the expressions of marker genes for oxidative stress and inflammatory cytokines in the liver of MSG mice. Taken together, SRT1720 treatment may reduce liver lipid accumulation, at least in part, by directly reducing the expressions of lipogenic genes. The reduction of oxidative stress and inflammation may also be involved in the amelioration of NAFLD.

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Spin-crossover (SCO) iron(III) compounds, [Fe(qnalOMe) 2 ]PF 6 ¢acetone (1) and [Fe(qnal-OMe) 2 ]BPh 4 ¢2MeOH (2) (qnal-OMe: 7-methoxy-1-[(8-quinolinylimino)methyl]-2-naphthalenol), were prepared and characterized by X-ray singlecrystal structure analysis, temperature-dependent magnetic susceptibility, and Mössbauer spectroscopy measurements. The compounds exhibited SCO behavior with thermal hysteresis loop (T 1/2 ↑ = 202 K, T 1/2 ↓ = 194 K for 1 and T 1/2 ↑ = 304 K, T 1/2 ↓ = 194 K for 2). Moreover, the light-induced excited spin-state trapping (LIESST) effect was observed for the compounds when the samples were illuminated (1000 nm) at 5 K. We suggest that the introduction of a strong intermolecular interaction, such as ππ stacking, can play an important role in the observed dynamic phase transition.Phase transitions induced by external stimuli (temperature, pressure, electric field, magnetic field, or light irradiation) have been investigated both for their intrinsic scientific interest and for their potential practical utilization. 13 Particularly, photoinduced phase transitions are very promising from the point of view of developing photoswitchable devices.46 Spin-crossover (SCO) compounds exhibiting conversion between high-spin (HS) and low-spin (LS) states are one category of phasetransition compounds with the SCO phenomenon very often observed in iron(II), iron(III), and cobalt(II) compounds. 7If intermolecular interactions in the solid state are sufficiently strong then cooperativity can result. Cooperativity normally induces abrupt spin transitions and hysteresis loops in SCO compounds, providing the rationale for the role of intermolecular interactions in influencing spin transitions having been extensively studied. 7,8 While the design of SCO compounds exhibiting large cooperativity remains a challenge, it has been proposed (and experimentally confirmed) that cooperativity can be increased by designing polymeric structures in which active sites are linked to each other by chemical bridges. Furthermore, SCO compounds with strong intermolecular interactions, such as ππ stacking or hydrogen bonding, can also exhibit abrupt transitions and hysteresis loops. 3,69Since Gütlich et al. observed a photoinduced LS ¼ HS transition of the iron(II) SCO compound [Fe(ptz) 6 ](BF 4 ) 2 in 1984, the phenomenon has been named light-induced excited spin-state trapping (LIESST). 5,7,8 It was demonstrated that reverse LIESST is also possible in some cases: illumination of the system with near-infrared light can also reverse the system to the LS state.7 The discovery of the LIESST effect suggested that such compounds could be used as optical switches, and a number of iron(II) LIESST compounds have been subsequently reported. 5,79As mentioned previously, we have suggested that the LIESST effect of iron(III) compounds with strong intermolecular interactions such as ππ stacking can be observed. In general, structural transition for typical iron(II) SCO compounds is considered by simple expanding and shrinking (stretching...

Excited-state symmetry breaking (ESB) has attracted much attention because it is often observed in symmetric multipolar chromophores designed as two-photon absorption/ emission materials. Herein, we report an ensemble and singlemolecule fluorescence imaging and spectroscopy investigation of ESB in hexakis[4-(p-dioctylaminostyryl)phenylethynyl]benzene-(DB6), a two-photon absorber possessing a C 6 -symmetric π−D 6 structure (π = hexaethynylbenzene, D = (p-dioctylaminostyryl)phenyl group) consisting of three equivalent D−π−D moieties. Ensemble and single-molecule measurements and theoretical calculations revealed that DB6 undergoes a photoabsorption process with two orthogonal transition dipole moments, whereas it fluoresces with a single transition dipole moment after one-or twostep ESB upon photoexcitation, depending on the environmental polarity. In nonpolar solvents and polymer films, one of the three D−π−D sites becomes planar, and the excited state is localized on this moiety: a [D δ+ −π δ− −D δ+ ]* quadrupolar state is formed. In polar solvents, the symmetry is further broken within the planarized D−π−D moiety, and the excited state is localized on one of the two D−π sites; i.e., a D−[π δ− −D δ+ ]* dipolar state is generated. Hence, DB6 can behave like a multichromophore with multiple emission sites in the molecule, which was demonstrated by stepwise photobleaching under photon antibunching conditions.