Design and Synthesis of Dually Branched 5′-Norcarbocyclic Adenosine Phosphonodiester Analogue as a New Anti-HIV Prodrug

A novel 3′,4′-dimethyl-5′-norcarbocyclic adenosine phosphonic acid was prepared using acyclic stereoselective route from 4-hydroxybutan-2-one (4). To improve the cellular permeability and enhance the anti-HIV activity of this phosphonic acid, a (bis)SATE phosphonodiester nucleoside prodrug (20) was prepared and its chemical stability was evaluated. The newly synthesized bis(SATE) analogue (20) and its parent nucleoside phosphonic acid (18) were assayed for anti-HIV activity using an in vitro assay system in a CEM cell line.     

Simple Synthesis and Anti-Hiv Activity of Novel 3′-Vinyl Branched Apiosyl Pyrimidine Nucleosides

Novel vinyl branched apiosyl nucleosides were synthesized in this study. Apiosyl sugar moiety was constructed by sequential ozonolysis and reductions. The bases (uracil and thymine) were efficiently coupled by glycosyl condensation procedure (persilyated base and TMSOTf). The antiviral activities of the synthesized compounds were evaluated against the HIV-1, HSV-1, HSV-2, and HCMV. Compound 10β displayed moderate anti-HIV activity (EC₅₀ = 17.3 μg/mL) without exhibiting any cytotoxicity up to 100 μM.     

Enhanced Phase II Detoxification Contributes to Beneficial Effects of Dietary Restriction as Revealed by Multi-platform Metabolomics Studies

Dietary restriction (DR) has many beneficial effects, but the detailed metabolic mechanism remains largely unresolved. As diet is essentially related to metabolism, we investigated the metabolite profiles of urines from control and DR animals using NMR and LC/MS metabolomic approaches. Multivariate analysis presented distinctive metabolic profiles and marker signals from glucuronide and glycine conjugation pathways in the DR group. Broad profiling of the urine phase II metabolites with neutral loss scanning showed that levels of glucuronide and glycine conjugation metabolites were generally higher in the DR group. The up-regulation of phase II detoxification in the DR group was confirmed by mRNA and protein expression levels of uridinediphospho-glucuronosyltransferase and glycine-N-acyltransferase in actual liver tissues. Histopathology and serum biochemistry showed that DR was correlated with the beneficial effects of low levels of serum alanine transaminase and glycogen granules in liver. In addition, the Nuclear factor (erythroid-derived 2)-like 2 signaling pathway was shown to be up-regulated, providing a mechanistic clue regarding the enhanced phase II detoxification in liver tissue. Taken together, our metabolomic and biochemical studies provide a possible metabolic perspective for understanding the complex mechanism underlying the beneficial effects of DR.It has been known for more than 70 years that dietary restriction (DR)¹ can extend the life span and delay the onset of age-related diseases, based on an early rodent study showing such effects (1). However, not until the 1980s was DR recognized as a good model for studying the mechanism of or inhibitory measures for aging (2). So far, extensive studies employing model organisms such as yeasts, nematodes, fruit flies, and rodents have shown that DR has beneficial effects in most of the species studied (for a review, see Ref. 3). Most notably, a recent 20-year-long study showed that monkeys, the species closest to humans, also benefit from DR similarly (4). Although there has not been (or could not have been) a systematic study on the effects of DR on the human life span, several longitudinal studies strongly suggest that changes in dietary intake can affect the life span and/or disease-associated marker values greatly (5–7).This inverse correlation between dietary intake and long-term health strongly indicates that DR''s effects should involve metabolism, and that DR elicits the reorganization of metabolic pathways. It also seems quite natural that something we eat should affect the body''s metabolism. Despite this seemingly straightforward relationship between diet and metabolism, the mechanisms underlying the beneficial effects of DR are anything but simple. Intensive efforts, spanning decades, to understand the mechanisms of DR have identified several genes that might mediate the effects of DR, such as mTOR, IGF-1, AMPK, and SIRT1 (for a review, see Ref. 8). Still, most of them are involved in early nutrient-sensing steps, and specific metabolic pathways, especially those at the final steps actually responsible for the effects of DR, are largely unknown.This might be at least partially due to the fact that previous studies have focused mostly on genomic or proteomic changes induced by DR, instead of looking at changes in metabolism or metabolites directly. Metabolomics, which has gained much interest in recent years (9–11), might be a good alternative for addressing the mechanistic uncertainty of DR''s effects, with the direct profiling of metabolic changes elicited by environmental factors. In contrast to genomics or proteomics, which often employ DNA or proteins extracted from particular tissues, metabolomics studies mostly employ body fluids (i.e. urine or blood), which can reflect the metabolic status of multiple organs, enabling investigations at a more systemic level. In particular, urine has been used extensively to study the mechanism of external stimuli (i.e. drugs or toxic insults) at most major target organs, such as the lung, kidney, liver, or heart (12–18). Still, metabolomics studies of DR effects have been very limited. A few previous ones reported the changes in phenomenological urine metabolic markers with DR, without identification and/or validation of specific metabolic pathways reflected at the actual tissue or enzyme level (19, 20). Therefore, those studies fell short of providing a mechanistic perspective on DR''s effects. In addition, they employed either NMR or LC/MS approaches without validation across the two analytical platforms.Among the metabolic pathways that can directly affect the integrity of multiple organs, and hence long-term health, are phase II detoxification pathways (21). Typically, lipophilic endo/xenobiotics are metabolized first by a phase I system, such as cytochrome P450, which modifies the compounds so that they have hydrophilic functional groups for increased solubility. In many cases, though, these modifications might increase the reactivity of the compounds, leading to cellular damage. The phase II detoxification systems involve conjugation reactions that attach charged hydrophilic molecular moieties to reactive metabolites, thus facilitating the elimination of the harmful metabolites from body, ultimately reducing their toxicity (22). These systems are thus especially important in protecting cellular macromolecules, such as DNA and proteins, from reactive electrophilic or nucleophilic metabolites. The enzymes involved in these processes include glutathione-S-transferase (GST), sulfotransferase, glycine-N-acyltransferase (GLYAT), and uridinediphospho-glucuronosyltransferase (UGT), with the last enzyme being the most prevalent (23). The beneficial effects of phase II reactions have been particularly studied in relation to the mechanism of healthy dietary ingredients. It is well believed that many such foods can prevent cancers (hence the term “chemoprevention”) by inducing phase II detoxification systems (24–26). Although DR also substantially reduces the incidence of cancers, the exact mechanism remains elusive.Here, we employed multi-platform metabolomics to obtain metabolic perspectives on the beneficial effects of DR on rats. Our results about urine metabolomics markers suggest that DR enhances the phase II detoxification pathway, which was confirmed by means of conjugation metabolite profiling and changes in mRNA/protein expression levels of phase II enzymes in actual liver tissues. A possible molecular mechanism was also addressed through the exploration of Nuclear factor (erythroid-derived 2)-like 2 (Nrf-2) pathway activation upon DR. We believe the current study provides new metabolic insights into DR''s beneficial effects, as well as a workflow for studying DR''s effects from a metabolic perspective.     

Effects of an electric pulse on variation of bacterial community and metabolite production in kimchi-making culture

Three, six, nine, and twelve V of electric pulse (EP) was applied to a culture of Weissella cibaria SKkimchi1 in MRS medium and kimchi-making culture (KMC). Viable cell number of SKkimchi1 in MRS medium was decreased in proportion to pulse intensity but that of bacteria in KMC was not. Lactic acid and ethanol produced by SKkimchi1 tended to be decreased in proportion to EP intensity but acetic acid was proportionally increased to EP intensity. Lactic acid, ethanol, and propionic acid produced in KMC were proportionally decreased, but acetic acid was proportionally increased to the EP intensity. Bacterial community and diversity in KMC were analyzed based on culture time by a temperature gradient gel electrophoresis (TGGE) technique. Most bacterial communities grown in freshly prepared kimchi belonged to Bacillus genus. Lactic acid bacteria responsible for kimchi fermentation began to grow on day 4, and were completely substituted for Bacillus genus on day 8, but some Bacillus genus began to grow again on day 12. However, bacterial community diversities were not different based on varying EP intensity.     

Overexpression of Neurospora crassa OR74A glutamate decarboxylase in Escherichia coli for efficient GABA production

This study investigated the effect of glutamate decarboxylase from Neurospora crassa OR74A on GABA production in Escherichia coli. GABA is one of the inhibitory neurotransmitters in the mammalian central nervous system, and can be used as a precursor of promising biopolymer Nylon 4. E. coli that overexpressed N. crassa glutamate decarboxylase was cultured at various pH levels and temperatures to determine optimum conditions for GABA production. When the recombinant E. coli strain was cultured at 30°C and pH 3, a final GABA concentration of 5.26 g/L was obtained from 10 g/L of monosodium glutamate (MSG), corresponding to a GABA yield of 86.23%.     

Evaluation of a novel pneumatic bioreactor system for culture of recombinant Chinese hamster ovary cells

Single use culture systems are a tool in research and biotechnology manufacturing processes and are employed in mammalian cell-based manufacturing processes. Recently, we characterized a novel bioreactor system developed by PBS Biotech. The Pneumatic Bioreactor System? (PBS) employs the Air-wheel?, which is a mixing device similar in structure to a water wheel but is driven by the buoyant force of gas bubbles. In this study, we investigated the physical properties of the PBS system, with which we performed biological tests. In 2 L PBS, the mixing times ranged from 6 (30 rpm, 0.175 vvm) to 15 sec (10 rpm, 0.025 vvm). The k_La value reached upto 7.66/h at 0.5 vvm, even without a microsparger, though this condition is not applicable for cell cultures. Also, when a 10 L PBS equipped with a microsparger was evaluated, a k_La value of upto approximately 20/h was obtained particularly in mild cell culture conditions. We performed cultivation of Chinese hamster ovary (CHO) cells in 2 and 10 L PBS prototypes. Results from the PBS were compared with those from an Erlenmeyer flask and conventional stirred tank type bioreactor (STR). The maximum cell density of 10.6 × 106 cells/mL obtained fromthe 2 L PBSwas about 2 times higher than that from the Erlenmeyer flask (5.6 × 10⁶ cells/mL) andwas similar to the STR (9.7 × 10⁶ cells/mL) when the CHO-S cells were cultured. These results support the general suitability of the PBS system using pneumatic mixing for suspension cell cultivation as a novel single-use bioreactor system.     

A putative role of Drep1 in apoptotic DNA fragmentation system in fly is mediated by direct interaction with Drep2 and Drep4

DNA fragmentation is common phenomenon for apoptotic cell death. DNA fragmentation factor, called DFF40 (CAD: mouse homologue), is a main nuclease for apoptotic DNA fragmentation. Nuclease activity of DFF40 is normally inhibited by DFF45 by tight interaction via CIDE domain without apoptotic stimuli. Once effector caspase is activated during apoptosis signaling, it cleave DFF45, allowing DFF40 to enter the nucleus and cleave chromosomal DNA. Unlike mammalian system, apoptotic DNA fragmentation in the fly might be controlled by four DFF-related proteins, known as Drep1, Drep2, Drep3 and Drep4. Although the function of Drep1 and Drep4 is well known as DFF45 and DFF40 homologues, respectively, the function of Drep2 and Drep3 is still unclear. DFF-related proteins contain a conserved CIDE domain of ~90 amino acid residues that is involved in protein–protein interaction. Here, we showed that Drep1 directly bind to Drep2 as well as Drep4 via CIDE domain. In addition, we found that the interaction of Drep2 and Drep4 to Drep1 was not competitive indicating that Drep2 and Drep4 bind different place of Drep1. All together, we suggest that Drep1 might be involved in apoptotic DNA fragmentation of fly system by direct interaction with Drep2 as well as Drep4.     

Anti-apoptotic mechanism of silkworm hemolymph in HeLa cell apoptosis

Silkworm hemolymph (SH) was found to exhibit anti-apoptotic activities in mammalian and insect cell systems. An anti-apoptotic mechanism of SH was investigated in a staurosporine-induced HeLa cell using flow cytometry, caspase assay, Immunoblot, and Immunochemistry. The addition of 5% SH to the medium resulted in lower intracellular activities of caspase-3 and caspase-9 after 0.6 μM of staurosporine treatment; however, SH did not directly inhibit the activities of those enzymes. This suggests SH inhibits the event upstream of these caspase activation steps, such as mitochondrial level events. We found from Immunoblot and Immunochemistry that cytochrome c release from the mitochondria was blocked by SH. SH also inhibited Bax translocation to the mitochondria. On the contrary, SH did not block the apoptosis when Bax is not involved in promoting apoptosis. With these results, we propose that SH protects mitochondria from apoptosis signal via blocking Bax translocation, and the subsequent apoptotic events are then inhibited. The inhibition of apoptosis using SH and its components may lead to new approaches for the minimization of cell death during commercial animal cell cultures.