A novel anti-hepatitis B virus (anti-HBV) agent, 2-fluoro-5-methyl-␤-L-arabinofuranosyluracil (L-FMAU), was synthesized and found to be a potent anti-HBV and anti-Epstein-Barr virus agent. Its in vitro potency was evaluated in 2.2.15 and H1 cells for anti-HBV and anti-Epstein-Barr virus activities, respectively. In vitro cytotoxicity in MT2, CEM, 2.2.15, and H1 cells was also assessed, and the results indicated high antiviral selectivities of L-FMAU in these cells.A number of nucleosides have been reported to be antihepatitis B virus (anti-HBV) agents, although none of them have yet been proven to be clinically useful. As a part of our antiviral drug discovery program for HBV, we recently have reported the syntheses and anti-HBV activities of dioxolane (14, 15) and oxathiolane (1,8,13) nucleosides. (Ϫ)-␤-L-Dioxolane-cytosine has been found to be the most potent anti-HBV agent (50% effective concentration ϭ 0.0005 M in 2.2.15 cells), although the compound was the most toxic (50% inhibitory concentration ϭ 0.26 M in CEM cells) among those tested (15). Among the oxathiolane cytosine nucleosides we evaluated, (Ϫ)-␤-L-oxathiolane-cytosine has the most potent anti-HBV activity (50% effective concentration ϭ 0.01 M) and a favorable cytotoxicity (Ͼ50 M in CEM cells) (1). Interestingly, the (Ϫ)-␤-L isomer of this compound resisted deoxycytidine deaminase, while the (ϩ)-␤-D isomer was deaminated under similar conditions (3).Recently, an increasing number of L nucleosides have been reported to be antiherpesvirus (23), anti-human immunodeficiency virus (anti-HIV) (2,6,13,14,16,19), and anti-HBV (1,7,8,10,11,15,16) agents. Furthermore, some of the L nucleosides have been found to be more potent than the corresponding D nucleosides (6,13,14). Previously, 2Ј-fluoro-5-methyl-␤-D-arabinofuranosyluracil (FMAU) and 2Ј-fluoro-5-ethyl-␤-Darabinofuranosyluracil (FEAU) were reported (5, 24, 27) to be extremely potent antiviral agents against herpesvirus and HBV, respectively. However, the myelosuppression and neurotoxicity of FMAU limit its usefulness as a clinically effective antiviral agent. In view of the discovery that several nucleosides with the unnatural L configuration are selective antiviral agents, it was of interest to synthesize several 2Ј-fluoro-substituted (arabino configuration) nucleosides with the L configuration as potential antiviral agents, anticipating that these nucleosides will give lower toxicities than the corresponding D isomers. Thus, we report here the preliminary syntheses and antiviral activities of several pyrimidine nucleosides for which the corresponding D isomers have been known to exhibit potent antiviral activities.Synthesis. 1-O-Acetyl-2,3,5-tri-O-benzoyl-␤-L-ribofuranose (compound 1) was prepared from L-ribose (Fig. 1). The fully protected L-ribose compound 1 was selectively debenzoylated at the C-2 position and then was converted to the 2-fluorinated sugar (compound 3) according to the method described for the corresponding D isomer (25). The 2-fluorosugar (arabino configuration) compound 3 was c...

GPR142, a putative amino acid receptor, is expressed in pancreatic islets and the gastrointestinal tract, but the ligand affinity and physiological role of this receptor remain obscure. In this study, we show that in addition to L-Tryptophan, GPR142 signaling is also activated by L-Phenylalanine but not by other naturally occurring amino acids. Furthermore, we show that Tryptophan and a synthetic GPR142 agonist increase insulin and incretin hormones and improve glucose disposal in mice in a GPR142-dependent manner. In contrast, Phenylalanine improves in vivo glucose disposal independently of GPR142. Noteworthy, refeeding-induced elevations in insulin and glucose-dependent insulinotropic polypeptide are blunted in Gpr142 null mice. In conclusion, these findings demonstrate GPR142 is a Tryptophan receptor critically required for insulin and incretin hormone regulation and suggest GPR142 agonists may be effective therapies that leverage amino acid sensing pathways for the treatment of type 2 diabetes.

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Since 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU) has been shown to be a potent anti-HBV agent in vitro, it was of interest to study the structure-activity relationships of related nucleosides. Thus, a series of 1-(2-deoxy-2-fluoro-beta-L-arabinofuranosyl)pyrimidine nucleosides have been synthesized and evaluated for antiviral activity against HBV in 2.2.15 cells. For this study, L-ribose was initially used as the starting material. Due to the commercial cost of L-ribose, we have developed an efficient procedure for the preparation of L-ribose derivative 6. Starting from L-xylose, 6 was obtained in an excellent total yield (70%) through the pyridinium dichromate oxidation of the 3-OH group followed by stereoselective reduction with NaBH4. It was further converted to the 1,3,5-tri-O-benzoyl-2-deoxy-2-fluoro-alpha-L-arabinofuranose (10), which was then condensed with various 5-substituted pyrimidine bases to give the nucleosides. Among the compounds synthesized, the lead compound, L-FMAU (13), exhibited the most potent anti-HBV activity (EC50 0.1 microM). None of the other uracil derivatives showed significant anti-HBV activity up to 10 microM. Among the cytosine analogues, the cytosine (27) and 5-iodocytosine (35) derivatives showed moderately potent anti-HBV activity (EC50 1.4 and 5 microM, respectively). The cytotoxicity of these nucleoside analogues has also been assessed in 2.2.15 cells as well as CEM cells. None of these compounds displayed any toxicity up to 200 microM in 2.2.15 cells. Thus, compound 13 (L-FMAU), 27, and 35 showed a selectivity of over 2000, 140, and 40, respectively.

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The objective of this study was to fabricate an acellular sheep periosteum and explore its potential application in guided bone regeneration. Sheep periosteum was collected and decellularized by a modified decellularization protocol. The effectiveness of cell removal was proved by hematoxylin and eosin and 4 0 ,6-diamidino-2-phenylindole staining, DNA quantitative test, and agarose gel electrophoresis. After decellularization, its microstructure was found to become more porous while the integrality of collagen fibers remained undamaged, and the contents of collagen and glycosaminoglycan were not decreased significantly. Biomechanical analysis showed that the elastic modulus was significantly declined, while the yield stress was not affected, probably due to the collagen integrality. In vitro study of CCK-8 assay demonstrated that the acellular periosteum not only had no toxic effect to the MC3T3-E1 cells, but benefited the cell proliferation to some degree. In vivo experiment of guided bone regeneration was performed using a rabbit cranial model.Micro-CT and histological results revealed that the acellular periosteum not only effectively prevented the ingrowth of fibrous connective tissues, but also potentially facilitated bone regeneration. In conclusion, acellular sheep periostea, with wider sources, less costs, and more convenient fabrication process, would have great potential in the employment for guided bone regeneration. K E Y W O R D S acellular periosteum, animal experiment, barrier membrane, extracellular matrix, guided bone regeneration

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