C–C bond coupling reactions illustrate the wealth of organic transformations, which are usually mediated by organotransition metal complexes. Here, we show that a borafluorene with a B–Cl moiety can mediate sequential alkyne insertion (1,2-carboboration) and deborylation/Csp2–Csp2 coupling reactions, leading to aromatic molecules. The first step, which affords a borepin derivative, proceeds very efficiently between the borafluorene and various alkynes by simply mixing these two components. The second step is triggered by a one-electron oxidation of the borepin derivative, which results in the formation of a phenanthrene framework. When an excess amount of oxidant is used in the second step, the phenanthrene derivatives can be further transformed in situ to afford dibenzo[g,p]chrysene derivatives. The results presented herein will substantially expand the understanding of main group chemistry and provide a powerful synthetic tool for the construction of a wide variety of extended π-conjugated systems.
SAMP8 mice have a shorter lifespan and show the dysfunction of the central nervous system. We here investigated whether soy peptides (SP) composed mainly of di- and tripeptides has the potential to prevent age-dependent cognitive impairment. SAMP8 and normal aging mice, SAMR1, were fed a diet supplemented with SP or a control diet for 26 weeks to investigate the preventive effects on the progression of cognitive decline using the Morris water maze. The SP-fed groups in SAMP8 and SAMR1 prevented the decline of cognitive ability compared to their controls. Increased expression of neurotrophic factors such as BDNF and NT-3 at mRNA and protein levels were observed in the brain of SP-fed mice, especially SAMP8. Further, the phosphorylated CREB protein level of SAMP8 was markedly up-regulated by SP feeding. These suggest that SPs have the potential for prevention of cognitive impairment via neurotrophic effects.
Alzheimer's disease (AD) is characterized by the progressive accumulation of extracellular β-amyloid (Aβ) aggregates. Recently, the senescence-accelerated mouse-prone 8 (SAMP8) model was highlighted as a useful model of age-related AD. Therefore, we used the SAMP8 mouse to investigate the preventive effects of sesame lignans on the onset of AD-like pathology. In preliminary in vitro studies, sesaminol showed the greatest inhibitory effect on Aβ oligomerization and fibril formation relative to sesamin, sesamolin, and sesaminol triglucoside. Hence, sesaminol was selected for further evaluation in vivo. In SAMP8 mice, feed-through sesaminol (0.05%, w/w, in standard chow) administered over a 16 week period reduced brain Aβ accumulation and decreased serum 8-hydroxydeoxyguanosine, an indicator of oxidative stress. Furthermore, sesaminol administration increased the gene and protein expression of ADAM10, which is a protease centrally involved in the non-amyloidogenic processing of amyloid precursor protein. Taken together, these data suggest that long-term consumption of sesaminol may inhibit the accumulation of pathogenic Aβ in the brain.
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