[Characterization and phylogenetic analysis of complete chloroplast genome of cultivated Qinan agarwood].

"Tangjie" leaves of cultivated Qinan agarwood were used to obtain the complete chloroplast genome using high-throughput sequencing technology. Combined with 12 chloroplast genomes of Aquilaria species downloaded from NCBI, bioinformatics method was employed to determine the chloroplast genome characteristics and phylogenetic relationships. The results showed that the chloroplast genome sequence length of cultivated Qinan agarwood "Tangjie" leaves was 174 909 bp with a GC content of 36.7%. A total of 136 genes were annotated, including 90 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. Sequence repeat analysis detected 80 simple sequence repeats(SSRs) and 124 long sequence repeats, with most SSRs composed of A and T bases. Codon preference analysis revealed that AUU was the most frequently used codon, and codons with A and U endings were preferred. Comparative analysis of Aquilaria chloroplast genomes showed relative conservation of the IR region boundaries and identified five highly variable regions: trnD-trnY, trnT-trnL, trnF-ndhJ, petA-cemA, and rpl32, which could serve as potential DNA barcodes specific to the Aquilaria genus. Selection pressure analysis indicated positive selection in the rbcL, rps11, and rpl32 genes. Phylogenetic analysis revealed that cultivated Qinan agarwood "Tangjie" and Aquilaria agallocha clustered together(100% support), supporting the Chinese origin of Qinan agarwood from Aquilaria agallocha. The chloroplast genome data obtained in this study provide a foundation for studying the genetic diversity of cultivated Qinan agarwood and molecular identification of the Aquilaria genus.

A concise synthesis of N-substituted fagomine derivatives and the systematic exploration of their α-glycosidase inhibition.

A novel and concise scheme has been developed successfully for the syntheses of N-substituted fagomine derivatives. The transformation of lactone (2) to 1,5-diol (3) was carried on with high yield (93-95%). The cyclization of 4 to 5 is a high stereoselective reaction (de value > 98%). It is disclosed that bulky substituent at N atom of the piperidine decreases the inhibition activity except those substituents having the ability of solvation or forming disulfide bond with M444 at the active site of α-glycosidase, which enhance the interaction with enzyme. Compounds with S-configuration at C-3 show greater activity than those with R-configuration. The structure-activity relationship study is also supported by molecular docking analysis.