Two-step Enzymatic Synthesis of Guanine Arabinoside

The chemical synthesis of Guanine arabinoside （ara-G） is extremely complex, time-consuming, and seriously polluted. A two-step enzymatic synthesis process was developed to acquire ara-G easily. 2,6-Diaminopurine arabinoside （ara-DA） was first synthesized with purine nucleoside phosphorylase and pyrimidine nucleoside phosphorylase produced by Enterobacter aerogenes DGW-07. The conversion yield of ara-DA could reach above 90% when the reaction liquid contained 30 mmol·L^-1 uracil arabinoside as arabinose donor, 10 mmol·L^- 1 2,6-diaminopurine as arabinose acceptor in pH 7.0 20 mmol·L^-1 phosphate buffer, and reacted at 60℃ for 48h. Then, ara-DA was effectively transformed into ara-G with adenylate deaminase produced by Aspergillus oryzae DAW-01. The total process had no complex separation and purification.

Induction of nucleoside phosphorylase in Enterobacter aerogenes and enzymatic synthesis of adenine arabinoside

Nucleoside phosphorylases (NPases) were found to be induced in Enterobacter aerogenes DGO-04, and cytidine and cytidine 5′-monophosphate (CMP) were the best inducers. Five mmol/L to fifteen mmol/L cytidine or CMP could distinctly increase the activities of purine nucleoside phosphorylase (PNPase), uridine phosphorylase (UPase) and thymidine phosphorylase (TPase) when they were added into medium from 0 to 8 h. In the process of enzymatic synthesis of adenine arabinoside from adenine and uracil arabinoside with wet cells of Enterobacter aerogenes DGO-04 induced by cytidine or CMP, the reaction time could be shortened from 36 to 6 h. After enzymatic reaction the activity of NPase in the cells induced remained higher than that in the cells uninduced.

New Octadecanoyl Diterpenoid Arabinoside from Conyza blinii

A new octadecanoyl diterpenoid glycoside,（E）-8α,15-dihydroxy-15-（3S-hydroxy-octadecanoyl）-13-labdene-8-O-α-L-arabinopyranoside（1）,was isolated from the aerial parts of Conyza blinii,and the structure was identified on the basis of a detailed spectroscopic analysis,including 2D NMR spectrometry and HRESI-MS.

INHIBITION OF NF-κB ACTIVITY ENHANCED CYTOSINE ARABINOSIDE INDUCED APOPTOSIS IN LEUKEMIC CELL LINE HL60-N

Objective: To explore the effects of dexamethasone (DXM) and vincristine (VCR) on cytosine arabinoside (Ara-C) induced apoptosis and activation of nuclear factor-k-gene binding (NF-kB) in leukemic cell line HL60-n. Methods: Apoptosis of HL60-n cells was analysed by TdT-mediated X-dUTP nick and end labeling (TUNEL) and DNA electrophoresis. NF-kB activity of HL60-n cells was detected by electrophoretic mobility shift assay (EMSA). Results: There was slight activation of NF-kB in HL60-n cells without drug induction. Ara-C at 1 mmol/L significantly enhanced the activation of NF-kB in HL60-n cells. The level of NF-kB activation induced by DXM at 1 mmol/L or VCR at 0.1 mmol/L had no significant difference compared with that of the control group. However, in HL60-n cells pre-treated with 1 mmol/L of DXM or 0.1 mmol/L of VCR, the activation of NF-kB induced by 1 mmol/L of Ara-C was significantly suppressed with inhibition rates of 31.0% and 47.0%, respectively. The apoptosis rates of HL60-n cells induced by 1.0 mmol/L, 10 mmol/L and 100 mmot/L Ara-C were 45.003.16%, 61.883.40% and 77.624.75%, respectively. The apoptotic rates of HL60-n cells induced by DXM at 1 mmol/L or VCR at 0.1 mmol/L were similar to that of the control group. However, either DXM at 1 mmol/L or VCR at 0.l mmol/L could enhance the apoptosis of HL60-n cells induced by Ara-C at 1 mmol/L with rates of 39.1% and 59.2%, respectively. Conclusion: Ara-C can induce apoptosis and activation of NF-kB in HL60-n cells. The mechanism of increased apoptosis of HL60-n cells by DXM or VCR may be related to suppression of NF-kB activation.

C_(19)-Diterpenoid alkaloid arabinosides from an aqueous extract of the lateral root of Aconitum carmichaelii and their analgesic activities

Eight new C_(19)-diterpenoid alkaloid arabinosides, named aconicarmichosides E–L(1–8), were isolated from an aqueous extract of the lateral roots of Aconitum carmichaelii(Fu Zi). Their structures were determined by spectroscopic and chemical methods including 2D NMR experiments and acid hydrolysis. Compounds 1–8, together with the previously reported four neoline 14-O-arabinosides from the same plant, represent the only examples of glycosidic diterpenoid alkaloids so far. At a dose of 1.0 mg/kg(i.p.), as compared with the black control, compounds 1, 2, and 4–6 exhibited analgesic effects with 465.6% inhibitions against acetic acid-induced writhing of mice. Structure–activity relationship was also discussed.

Outcomes of CAG Regimen for Refractory Biphenotypic Acute Leukemia Patients

Objective To evaluated the efficiency of low-dose cytosine arabinoside plus aclarubicin with concurrent administration of granulocyte colony-stimulating factor （CAG） regimen for refractory biphenotypic acute leukemia （BAL）. Methods We treated 5 refractory BAL patients by CAG regimen （10 mg.m 2 cytosine arabinoside subcutaneously administrated every 12 hours, day 1-14; 5-7 mg·m^-2 aclarubicin intravenously administrated daily, day 1-8; and concurrently used 200 μg·m^-2·d^-1 granulocyte colony-stimulating factor subcutaneously） from November 2002 to April 2007. The efficacy of the regimen was evaluated by response rate, and the side effects were also measured. Results The complete remission rate was 80%, median duration of absolute neutrophil count〈5.0×10^8/L and platelet count〈2.0×10^10/L was day 13 and day 1, respectively; and the infection rate was low （Ⅲ-Ⅳ infection rate, 20.00%）.