Chemical approaches for the stereocontrolled synthesis of 1,2-cis-β-D-rhamnosides / 中国天然药物

In carbohydrate chemistry, the stereoselective synthesis of 1,2-cis-glycosides remains a formidable challenge. This complexity is comparable to the synthesis of 1,2-cis-β-D-mannosides, primarily due to the adverse anomeric and Δ-2 effects. Over the past decades, to attain β-stereoselectivity in D-rhamnosylation, researchers have devised numerous direct and indirect methodologies, including the hydrogen-bond-mediated aglycone delivery (HAD) method, the synthesis of β-D-mannoside paired with C6 deoxygenation, and the combined approach of 1,2-trans-glycosylation and C2 epimerization. This review elaborates on the advancements in β-D-rhamnosylation and its implications for the total synthesis of tiacumicin B and other physiologically relevant glycans.

Resveratrol promotes mitochondrial energy metabolism in exerciseinduced fatigued rats

BACKGROUND/OBJECTIVES@#To investigate the effect and regulatory mechanism of resveratrol supplementation on the mitochondrial energy metabolism of rats with exerciseinduced fatigue.MATERIALS/METHODS: Forty-eight Sprague-Dawley male rats were divided randomly into a blank control group (C), resveratrol group (R), exercise group (E), and exercise and resveratrol group (ER), with 12 rats in each group. Group ER and group E performed 6-wk swimming training with 5% wt-bearing, 60 min each time, 6 days a wk. Group ER was given resveratrol 50 mg/kg by gavage one hour after exercise; group R was only given resveratrol 50 mg/kg by gavage; group C and group E were fed normally. The same volume of solvent was given by gavage every day. @*RESULTS@#Resveratrol supplementation could reduce the plasma blood urea nitrogen content, creatine kinase activity, and malondialdehyde content in the skeletal muscle, increase the total superoxide dismutase activity in the skeletal muscle, and improve the fatigue state.Resveratrol supplementation could improve the activities of Ca2+ -Mg2+ -ATPase, Na+ -K+ -ATPase, succinate dehydrogenase, and citrate synthase in the skeletal muscle. Furthermore, resveratrol supplementation could up-regulate the sirtuin 1 (SIRT1)-proliferator-activated receptor gamma coactivator-1α (PGC-1α)-nuclear respiratory factor 1 pathway. @*CONCLUSIONS@#Resveratrol supplementation could promote mitochondrial biosynthesis via the SIRT1/PGC-1α pathway, increase the activity of the mitochondrial energy metabolismrelated enzymes, improve the antioxidant capacity of the body, and promote recovery from exercise-induced fatigue.

The research on the technology of vacuum coating developing fingerprints and the profiling of DNA on the objects of cloth / 中国法医学杂志

Objectives To conduct a research on the possibility and effect factors of latent fingerprints development in clothing objects after vacuum coating, and extracting fingerprints DNA and to probe in the relation among DNA template quantity and genetic loci numbers tested, and the rfu value after coating. Methods To select two groups that are free sweat hands and sweat hands and have them press their fingerprints on the cloth, after coating, and to analyze the effect of time, to quantify and test the targeted fingerprints DNA, to compare the locus numbers tested between white and black cloth. Results As the time is prolonged, the locus numbers tested decrease. The locus numbers tested on the group of sweat hands using the same method after the same placed time are lager than the free sweat hands. When the value of rfu is 600 above, the ratio of the locus numbers tested is more than 90% and the threshold of templates is 0.013ng. The locus numbers tested of white cloth is larger, comparing with black cloth when using the same method. What is more, there exists an prohibitive influence of pigments of the dyed cloth over the PCR amplification, to put it further, the loci numbers tested will be trimmed. Conclusion The technology of vacuum coating can be well used in the area of detecting fingerprint DNA.

C-6′aminomethylation modification in gentamicin biosynthesis gene cluster / 中国药科大学学报

@#This study explored the C-6′aminomethylation modification in gentamicin biosynthesis gene cluster. Plasmid pFT104 used for the genT in-frame deletion was constructed and transformed into M. purpurea G1008 by conjugation. Mutant M. purpurea GT106(ΔgenT)confirmed by apramycin resistance and PCR amplification was then obtained. Next, a recombinant plasmid pFTN203 was constructed for blocking-up genN. pFTN203 was introduced into M. purpurea GT106 by conjugation. A desired mutant strain GTN205(ΔgenT+genN)was obtained by PCR analysis. Finally, based on the role of genK in C′-6 methylation, the mutant strain GTNK308(ΔgenT+genN+genK)was selected by knocking out genK. Metabolites were isolated from the fermentation broths of mutant strains and analyzed by MS. The results indicated that the metabolites of M. purpurea GT106(ΔgenT)did not change compared with the original strain G1008. The mutant strain GTN205(ΔgenT+ genN)no longer produced gentamicin C1, and yet accumulated in gentamicin C1a and C2. Gentamicin C2b was no longer detected in the metabolites of strain GTNK308(ΔgenT+genN+genK). These results showed that the inactivation of genN led to the blocking of the synthesis of gentamicin C1 and C2b. It suggested that genN might participate in the modification of aminomethylation at C-6′of purpurosamine, while genT was not involved in the C-6′aminomethylation.