Efficient Synthesis of the Disialylated Tetrasaccharide Motif in N-Glycans through an Amide-Protection Strategy.

A disialylated tetrasaccharide, Neu5Ac(α2,3)Gal(ß1,3)[Neu5Ac(α2,6)]GlcNAc (1), which is found at the termini of some N-glycans, has been synthesized. Compound 1 was obtained through an α-sialylation reaction between a sialic acid donor and a trisaccharide that was synthesized from the glycosylation of a sialylated disaccharide with a glucosaminyl donor. This synthetic route enabled the synthesis of the as-described disialylated structure. A more-convergent route based on the glycosylation of two sialylated disaccharides was also established to scale up the synthesis. Protection of the amide groups in the sialic acid residues significantly increased the yield of the glycosylation reaction between the two sialylated disaccharides, thus suggesting that the presence of hydrogen bonds on the sialic acid residues diminished their reactivity.

Reinvestigation of the C5-acetamide sialic acid donor for α-selective sialylation: practical procedure under microfluidic conditions.

Despite the previous literature describing the "low-to-modest" efficiency, the readily available C5-acetamide donor was reinvestigated for its use in α-sialylation under microfluidic conditions. The N-phenyltrifluoroacetimidate donor was efficiently mixed with an appropriate amount of TMSOTf to produce the α(2-6) and α(2-3)-sialylation products of galactose and glucosamine acceptors in excellent yields and with nearly perfect α-selectivity.

[Effect of additives on absorption of Coptis chinensis total alkaloids and pharmacokinetics in mice].

OBJECTIVE: To evaluate the effect of additives on absorption of Coptis chinensis total alkaloid and their pharmacokinetics in mice. METHOD: The mice were fed with the mixture of C. chinensis total alkaloids and additives (1:1). And then the feces and orbital blood were taken to detect the content of total alkaloids by HPLC and their pharmacokinetics. RESULT: Glutin could make the absorption of jatrorrhizine, coptisine, berberine and total alkaloids increased by 30%. Tween 80 and arabic gum did not affect the absorption of berberine, but inhibit that of other alkaloids. There had no influence of lecithin on the absorption of alkaloids. The peak time of total alkaloids in blood were 2 h (Cmax 1=5.9 mg x L(-1)) and 5.0 h (Cmax 2=3.4 mg x L(-1)), respectively, AUC was 17.6 mg x h x L(-1), the elimination of Half-life t1/2 was 5.2 h. After addition of glutin, the peak time of total alkaloids in blood were 1.5 h (Cmax 1=7.6 mg x L(-1)) and 4.8 h (Cmax 2=8.5 mg x L(-1)), AUC was up to 31.1 mg x h(-1) x L(-1), the elimination of Half-life t1/2 was 6.2 h. CONCLUSION: Glutin could accelerate the mice on the absorption of C. chinensis total alkaloids, to extend the elimination half-life, increase the blood concentration and bioavailability.

7-Chloro-4-phenethyl-2H-1,4-benzoxazin-3(4H)-one.

In the crystal structure of title compound, C(16)H(14)ClNO(2), the dihedral angle between the aromatic rings is 4.2 (2)°.

Synthesis and antimicrobial activity of 3-alkoxyjatrorrhizine derivatives.

The compounds 3-ethoxy- ( 2), 3-butoxy- ( 3), 3-hexyloxy- ( 4), 3-octyloxy- ( 5), 3-decyloxy- ( 6) and 3-dodecyloxyjatrorrhizine chlorides ( 7) were synthesized and tested for their antimicrobial activity in vitro to evaluate structure-activity relationships. Substitution of the H with alkyl groups at C-3-OH led to significant changes in the antimicrobial activity. The antimicrobial activity of the substituted derivatives was 32 - 1000 times higher than that of jatorrhizine ( 1), which increased as the aliphatic chain was elongated and then decreased slightly when the alkyl chain exceeded eight carbon atoms. 3-Octyloxyjatrorrhizine ( 5) displayed the highest antimicrobial activity of all compounds. The LD (50) values of compounds 1 - 7 were more than 6000 mg/kg body weight, showing a low toxicity. The toxicities of compounds 2 - 7 were slightly lower than that of ( 1).