No abstract

The gustation system for sweeteners is well-known to be regulated by nutritional and metabolic conditions, but there is no or little information on the underlying mechanism. Here, we examined whether elevation of the blood glucose level was involved in alteration of the expression of sweet taste receptors in circumvallate papillae (CP) and sweet taste sensitivity in male Sprague-Dawley rats. Rats under 4 h-fed conditions following 18 h-fasting exhibited elevated blood glucose levels and decreased pancreatic T1R3 expression, compared to rats after 18 h-fasting treatment, and they exhibited increased protein expression of sweet taste receptors T1R2 and T1R3 in CP. Under streptozotocin (STZ)-induced diabetes mellites (DM) conditions, the protein expression levels of T1R2 and T1R3 in CP were higher than those under control conditions, and these DM rats exhibited increased lick ratios in a low sucrose concentration range in a brief access test with a mixture of sucrose and quinine hydrochloride (QHCl). These findings indicate that the elevation of blood glucose level is a regulator for an increase in sweet taste receptor protein expression in rat CP, and such alteration in STZ-induced DM rats is involved in enhancement of their sweet taste sensitivity.

One of the earliest charge-transfer complexes synthesized is dinaphtho[2,1,1′,2′]furan picrate, which was first reported in 1905. Here, we synthesized and structurally characterized this complex. This complex has a stoichiometric ratio of 1:1 and a melting point of 161.4 C. The bond distances and angles of the component molecules are within the range of those reported for structurally similar neutral compounds and picric acid. These characteristics taken together with the feature that the infrared spectra of the complex can be superimposed with those of its component molecules, it is concluded that this complex is in the neutral ground state. The component molecules are stacked alternately, producing a •••DA-DA-DA••• one-dimensional column in the b-axis direction. The compound crystallizes in a monoclinic system and was characterized thus: P21/c, a = 10.0912(18), b = 7.5548(11), c = 27.919(5)Å, β = 94.047(4) , Z = 4, V = 2123.2(6)Å 3. The crystal structure was solved by direct methods and refined by full-matrix least-squares on F 2 to final values of R1 = 0.0502 and wR2 = 0.1190.

No abstract

Treatment of p‐toluenesulfonic acid on bipyrenol in PhCl gave a pyrene‐fused furan. The expansion of the molecule induced a narrow HOMO‐LUMO gap, multiple redox processes showing both oxidation and reduction, and a bathochromic shift in the absorption spectrum. A small Stokes shift was caused by the rigidity of the molecule. The structures and electronic states were estimated by theoretical considerations. We found that the heteroatom containing a [5]helicene molecule shows racemization through a planar transition state.