[Identification of main chemical constituents of diterpene lactone effective fraction of Andrographis panniculata by HPLC-DAD/ESI-MS and their preliminary pharmacodynamics research].

OBJECTIVE: To establish an HPLC-DAD/ESI-MS method for quickly identifying chemical constituents in diterpene lactone effective fraction of Andrographis panniculata and to study its pharmacodynamics. METHOD: The separation was performed on an Agilent SB-C18 column (2.1 mm x 150 mm, 5 µm) with a mobile phase of acetonitrile (A) and water (B). The flow rate was maintained at 0.4 mL x min(-1) and detection wavelength was set at 205 nm. The samples were analyzed in positive ion mode, and mass scan range was m/z 50-1 000. Using two kinds of tumor cell lines made living animal models, and studied preliminary pharmacodynamics on anti-tumor aspect. RESULT: Five diterpene lactones in the diterpene lactone effective fraction of A. panniculata could be separated in one run. Pharmacodynamic experiments showed that the effectve fraction had an inhibitory effect on the growth of tumor. CONCLUSION: A rapid and efficient HPLC-ESI-MS method to determine the chemical constituents in diterpene lactone effective fraction of A. panniculata has been established, and the preliminary pharmacodynamics research has been done, which could be used for the quality control and further studies of diterpene lactone effective fraction of A. panniculata in vivo.

Molecular cloning, expression and characterization of the porcine ß defensin 2 in E. coli.

Porcine ß defensin 2(pBD2)is a cationic 37-amino acid antimicrobial peptide with disulfide bonds. Synthetic pBD2 had broad antimicrobial activity against pathogenic bacteria, and thus pBD2 could be a good candidate as a bactericidal agent for pigs. This study reported the successful recombinant expression of pBD2 in Escherichia coli and analysis of its antimicrobial activity, its hemolytic activity, salt-tolerance and thermal stability as well. The pBD2 gene, obtained by RT-PCR using the tongue total RNA as a template and cloned into pET30a expression vector, was transformed into E. coli BL21 (DE3) plysS. The recombinant pBD2 was expressed after induction by IPTG and purified by His tag affinity column with 95% purity. The recombinant pBD2 exhibited antimicrobial activity against both Gram-positive S. aureus and Gram-negative E. coli including the multi-resistant E. coli. The minimum inhibitory concentration (MIC) of recombinant pBD2 against tested bacteria was 10 µg/mL, and the recombinant pBD2 could kill 50% E. coli at 14.39 µg/mL and S. aureus at 21.1 µg/mL. In addition, pBD2 showed low hemolytic activity, salt-tolerance and thermal stability, the properties would be important for its application in practice.

Cloning, expression and characterization of antimicrobial porcine ß defensin 1 in Escherichia coli.

Porcine ß defensin 1 (pBD1) is a cationic antimicrobial peptide with three pairs of disulfide bonds. When expressed in insect cells, two polypeptides of different length (pBD1(38) and pBD1(42)) accumulated, which differed by N-terminal truncation. However, only pBD1(42) was found in pigs. pBD1(42) had stronger antimicrobial activity than pBD1(38), and thus could be a good candidate as a bactericidal agent for pigs. In this study, pBD1(42) gene, obtained by RT-PCR using the tongue total RNA as a template, was cloned into pET30a expression vector and transformed into Escherichia coli BL21 (DE3) plysS. The recombinant pBD1(42) was expressed after induction by IPTG and purified by His tag affinity column with 90% purity. The recombinant pBD1(42) exhibited antimicrobial activity against both Gram-positive Staphylococcus aureus and Gram-negative E. coli including the multi-resistant E. coli. The minimum inhibitory concentrations (MICs) of recombinant pBD1(42) against tested bacteria were 100 µg/mL for E. coli and 80 µg/mL for S. aureus. In addition, pBD1(42) showed low hemolytic activity and high thermal stability. These properties are relevant for the biotechnological applications of the peptide.