Simultaneous Enantioseparation of Aldohexoses and Aldopentoses Derivatized With L‐Tryptophanamide by Reversed Phase HPLC Using Butylboronic Acid as a Complexation Reagent of Monosaccharides

Three aldohexoses, glucose, galactose, and mannose, and three aldopentoses, arabinose, xylose, and ribose, were derivatized with L‐tryptophanamide (L‐TrpNH₂) under alkaline conditions. Using a basic mobile phase (pH 9.2), the three aldohexoses or the three aldopentoses were simultaneously enantioseparated, respectively, but all the six monosaccharides could not be simultaneously enantioseparated. A large amount of nonreacted L‐TrpNH₂ was detected after the derivatized monosaccharides. In order to widen the separation window, a large portion of nonreacted L‐TrpNH₂ could be eliminated by liquid–liquid extraction with ethylacetate, and elution order of the derivatized monosaccharides and nonreacted L‐TrpNH₂ was found to be reversed using a neutral mobile phase. All of the six monosaccharides were simultaneously enantioseparated by reversed phase high‐performance liquid chromatography (HPLC) using InertSustainSwift C18 column (4.6 mm i.d. × 150 mm) and a mobile phase containing 180 mM phosphate buffer (pH 7.6), 1.5 mM butylboronic acid, and 5% acetonitrile at 40 °C. Nomenclature of D and L for monosaccharides is based on the configurations of the asymmetric C4 center for aldopentoses and C5 center for aldohexoses. It was found that the enantiomer elution order of these six monosaccharides and fucose in the proposed method conformed to be the absolute configuration of the C2 center. Chirality 27:417–421, 2015. © 2015 Wiley Periodicals, Inc.     

Orientation and Order of the Amide Group of Sphingomyelin in Bilayers Determined by Solid-State NMR

Sphingomyelin (SM) and cholesterol (Chol) are considered essential for the formation of lipid rafts; however, the types of molecular interactions involved in this process, such as intermolecular hydrogen bonding, are not well understood. Since, unlike other phospholipids, SM is characterized by the presence of an amide group, it is essential to determine the orientation of the amide and its order in the lipid bilayers to understand the nature of the hydrogen bonds in lipid rafts. For this study, 1′-¹³C-2-¹⁵N-labeled and 2′-¹³C-2-¹⁵N-labeled SMs were prepared, and the rotational-axis direction and order parameters of the SM amide in bilayers were determined based on ¹³C and ¹⁵N chemical-shift anisotropies and intramolecular ¹³C-¹⁵N dipole coupling constants. Results revealed that the amide orientation was minimally affected by Chol, whereas the order was enhanced significantly in its presence. Thus, Chol likely promotes the formation of an intermolecular hydrogen-bond network involving the SM amide without significantly changing its orientation, providing a higher order to the SM amide. To our knowledge, this study offers new insight into the significance of the SM amide orientation with regard to molecular recognition in lipid rafts, and therefore provides a deeper understanding of the mechanism of their formation.     

Nuclear-translocated Glyceraldehyde-3-phosphate Dehydrogenase Promotes Poly(ADP-ribose) Polymerase-1 Activation during Oxidative/Nitrosative Stress in Stroke

In addition to its role in DNA repair, nuclear poly(ADP-ribose) polymerase-1 (PARP-1) mediates brain damage when it is over-activated by oxidative/nitrosative stress. Nonetheless, it remains unclear how PARP-1 is activated in neuropathological contexts. Here we report that PARP-1 interacts with a pool of glyceradehyde-3-phosphate dehydrogenase (GAPDH) that translocates into the nucleus under oxidative/nitrosative stress both in vitro and in vivo. A well conserved amino acid at the N terminus of GAPDH determines its protein binding with PARP-1. Wild-type (WT) but not mutant GAPDH, that lacks the ability to bind PARP-1, can promote PARP-1 activation. Importantly, disrupting this interaction significantly diminishes PARP-1 overactivation and protects against both brain damage and neurological deficits induced by middle cerebral artery occlusion/reperfusion in a rat stroke model. Together, these findings suggest that nuclear GAPDH is a key regulator of PARP-1 activity, and its signaling underlies the pathology of oxidative/nitrosative stress-induced brain damage including stroke.     

Dysregulation of the Bmi‐1/p16Ink4a pathway provokes an aging‐associated decline of submandibular gland function

Bmi‐1 prevents stem cell aging, at least partly, by blocking expression of the cyclin‐dependent kinase inhibitor p16^Ink4a. Therefore, dysregulation of the Bmi‐1/p16^Ink4a pathway is considered key to the loss of tissue homeostasis and development of associated degenerative diseases during aging. However, because Bmi‐1 knockout (KO) mice die within 20 weeks after birth, it is difficult to determine exactly where and when dysregulation of the Bmi‐1/p16^Ink4a pathway occurs during aging in vivo. Using real‐time in vivo imaging of p16^Ink4a expression in Bmi‐1‐KO mice, we uncovered a novel function of the Bmi‐1/p16^Ink4a pathway in controlling homeostasis of the submandibular glands (SMGs), which secrete saliva into the oral cavity. This pathway is dysregulated during aging in vivo, leading to induction of p16^Ink4a expression and subsequent declined SMG function. These findings will advance our understanding of the molecular mechanisms underlying the aging‐related decline of SMG function and associated salivary gland hypofunction, which is particularly problematic among the elderly.     

Substitution at carbon 2 of 19-nor-1α,25-dihydroxyvitamin D3 with 3-hydroxypropyl group generates an analogue with enhanced chemotherapeutic potency in PC-3 prostate cancer cells

The active form of vitamin D(3), 1α,25-dihydroxyvitamin D(3)(1α,25(OH)(2)D(3)), has anti-proliferative and anti-invasive activities in prostate cancer cells. Because of 1α,25(OH)(2)D(3) therapeutic potential in treating cancers, numerous analogues have been synthesized with an attempt to increase anti-proliferative and/or decrease calcemic properties. Among these analogues, 19-nor-1α,25(OH)(2)D(2) while being less calcemic has equivalent potency as 1α,25(OH)(2)D(3) in several in vitro and in vivo systems. We recently showed that 19-nor-2α-(3-hydroxypropyl)-1α,25(OH)(2)D(3) (MART-10) was at least 500-fold and 10-fold more active than 1α,25(OH)(2)D(3) in inhibiting the proliferation of an immortalized normal prostate PZ-HPV-7 cells and the invasion of androgen insensitive PC-3 prostate cancer cells, respectively. In this study, we further investigated the effects of MART-10 and 1α,25(OH)(2)D(3) on the dose- and time-dependent induction of CYP24A1 gene expression in PC-3 prostate cancer cells. We found that MART-10 induced CYP24A1 gene expression at a lower concentration with a longer duration compared to 1α,25(OH)(2)D(3), suggesting that MART-10 is less susceptible to CYP24A1 degradation. Molecular docking model of human CYP24A1 and MART-10 indicates that its side chain is far away from the heme ion and is less likely to be hydroxylated by the enzyme. Furthermore, MART-10 was a more potent inhibitor of PC-3 cell proliferation and invasion compared to 1α,25(OH)(2)D(3). In addition, MART-10 down-regulated matrix metalloproteinase-9 (MMP-9) expression which could be one mechanism whereby MART-10 influences cancer cell invasion. Finally, we observed that subcutaneous administration of MART-10 up-regulated the CYP24A1 mRNA expression in rat kidneys without affecting their plasma calcium levels. Thus, our findings demonstrate that MART-10 is biologically active in vivo and may be an effective vitamin D analogue for clinical trials to treat prostate cancer.     

Total biosynthesis of diterpene aphidicolin, a specific inhibitor of DNA polymerase α: heterologous expression of four biosynthetic genes in Aspergillus oryzae

Clustering of biosynthetic genes for producing fungal secondary metabolites, which frequently consist of less than ten genes, has been recognized with numerous genomes. The heterologous expression of whole genes in the clusters will therefore produce various types of natural products when using a suitable fungal host. We introduced the whole gene cluster for the biosynthesis of diterpene aphidicolin into the fungal quadruple auxotrophic host, Aspergillus oryzae, by using four different vectors (pTAex3, pPTRI, pUSA and pAdeA) which harbor a starch-inducible promoter/terminator to examine the expression conditions. The resulting quadruple transformant carrying the genes of geranylgeranyl diphosphate synthase PbGGS, terpene synthase PbACS, and two monooxygenases (PbP450-1 and PbP450-2) produced aphidicolin. The double and triple transformants also respectively produced aphidicolan-16β-ol and 3-deoxyaphidicolin. Alternative host Saccharomyces cerevisiae carrying the genes, PbGGS and PbACS, produced key intermediate aphidicolan-16β-ol. This is the first example of a total biosynthesis of terpenoids using fungal hosts.     

Methotrexate chronotherapy is effective against rheumatoid arthritis

Methotrexate (MTX) is the most important drug for treating rheumatoid arthritis (RA). It has been stated that cytokines play an important role in the pathogenesis of RA, and that cytokine levels increase and show 24-h rhythms in RA patients. Previously, we found that arthritis was relieved after the administration of MTX at specific times in synchronization with the 24-h rhythm of tumor necrosis factor (TNF)-α in collagen-induced arthritis (CIA) animals. Based on our findings in an earlier study of the dosing time-dependent effects of MTX in MRL/lpr mice, which develop autoimmune disorders that share similarities with human RA, we examined here the utility of MTX chronotherapy in Japanese RA patients. In an initial animal modeling study, we collected blood from MRL/lpr mice at different times (2, 6, 10, 14, 18, or 22 hours after the light was turned on [HALO]), and we measured TNF-α mRNA expression in leukocytes. MTX was administered to the mice at two different dosing times (6 or 18 HALO), and various blood parameters were measured to estimate arthritis activity. TNF-α mRNA levels showed a clear 24-h rhythm with a peak at 22 HALO and a trough at 18 HALO after RA had developed. In these MRL/lpr mice, inflammation and TNF-α were markedly reduced when the MTX dosing time was matched to the time (18 HALO) when the TNF-α level began to increase. We then applied these findings to Japanese RA patients by switching them from the standard MTX three times/wk (day 1: after breakfast and supper; day 2: after breakfast schedule), to chronotherapy, in which the dose and number of doses/wk were not changed but MTX was administered once-a-day at bedtime. Disease Activity Score (DAS)28, modified health assessment questionnaire (MHAQ), and adverse effects were assessed. With MTX chronotherapy, DAS28, which is commonly used to quantitatively assess RA symptoms, was significantly improved at all follow-up clinical visit times compared with the baseline (vs. 1 mo: p?=?.0197, 2 mos: p?=?.0107, 3 mos: p?=?.0087). Significant symptom recovery was observed in 41.2% of patients, and 23.5% of patients achieved clinical remission during the 3 mos of follow-up. Functional capacity of RA patients, as indicated by the MHAQ, was markedly improved by chronotherapy. There were no severe adverse effects. Thus, we demonstrated (i) inflammation and plasma TNF-α concentrations were significantly reduced in MRL/lpr mice treated with MTX at 18 HALO, the time when TNF-α mRNA level began to increase; and (ii) MTX bedtime chronotherapy was safe, markedly reduced disease activity, and improved the functional capacity of RA patients. The findings on RA patients show that bedtime MTX chronotherapy can improve RA symptoms compared to the current standard dosing methods.