Molecular diversity and hypoglycemic polypeptide-P content of Momordica charantia in different accessions and different seasons.

BACKGROUND: Momordica charantia (MC) has been used for treating diabetes mellitus from ancient times in Asia, Africa and South America. There are many MC accessions in local markets. Polypeptide-P as a main hypoglycemic component in MC was first studied in this experiment to illustrate the different contents in MC of different accessions and different harvesting times. RESULTS: Nineteen MC accessions collected from different regions were clustered into three groups using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) molecular markers. Content of polypeptide-P in the tested MC accessions was detected by western blot (WB) method. The WB results revealed that polypeptide-P was detected in MC accessions harvested in June and July but not in September and October. Furthermore, Polypeptide-P content corresponded well with the MC accessions. CONCLUSION: Our results suggest that the MC accessions and the harvesting times or the weather during harvest play significant roles in high content of polypeptide-P.

[Expression of human estrogen receptor alpha and beta in Escherichia coli].

Estrogen participates in many life activities through combination with estrogen receptor alpha (ERalpha) or estrogen receptor beta (ERbeta) in the body. In order to establish an in vitro estrogen-like compound screening model, the coding region of human ERalpha and ERbeta was separately constructed into pET32-ERalpha and pET43-ERbeta prokaryotic expression vector and water-soluble recombinant ERalpha and ERbeta proteins were expressed in Escherichia coli strain BL21. Western blotting revealed that both recombinant proteins have estrogen receptor binding sites. The proteins were purified using S-Tag affinity Purification Kit and digested with enterokinase to get the ERalpha and ERbeta proteins. About 0.90 mg of ERalpha and 0.65 mg of ERbeta were obtained at the concentration of 0.181 and 0.131 mg x mL(-1), respectively.

Tandem multimer expression and preparation of hypoglycemic peptide MC6 from Momordica charantia in Escherichia coli.

Tandem repeat multimers of Momordica charantia (MC) peptide MC6 were designed and the recombinant plasmid containing 10 copies of MC6 gene was constructed to improve the expression level of MC6 in Escherichia coli. Under the selected conditions of cultivation and induction, the expression level of recombinant TrxA-MC6(10) protein was above 25% of total bacteria protein. This fusion protein was purified and cleaved with HCl (13%, w/v). Either the un-cleaved or cleaved recombinant proteins was analyzed pharmacological activity by alloxan-induced diabetic mice and only the cleaved products of the recombinant protein showed significant hypoglycemic effects. The study provides a convenient and economical method for the large-scale production of anti-diabetic medicines for pharmaceutical applications.

Gene cloning and expression of a novel hypoglycaemic peptide from Momordica charantia.

BACKGROUND: Momordica charantia (MC) is used in many Asian countries as a traditional functional food and medicine. Polypeptide-P, a 166 amino acid (AA) polypeptide isolated from MC seeds, has been reported to show hypoglycaemic effects in patients with type I or type II diabetes. The AA sequence of this peptide has been determined, but its gene sequence has yet to be published. RESULTS: In this study a gene-cloning strategy was employed to obtain the polypeptide-P gene sequence using degenerate reverse transcription polymer chain reaction and genome-walking methods. A complete 498 bp sequence encoding the polypeptide-P protein was cloned from MC seeds. Subsequent assays of the bioactivity of the expressed recombinant protein revealed that it had significant hypoglycaemic activity in alloxan-induced diabetic mice. This result suggests that recombinant polypeptide-P has hypoglycaemic effects. CONCLUSION: This is the first report of cloning and expression of the MC polypeptide-P gene. The cloned gene could be helpful for exploring the mechanisms of polypeptide-P gene expression and regulation in MC. Furthermore, this gene could be used as a potential tool both for screening MC varieties with high hypoglycaemically active substance content and for breeding new varieties of MC with high economic value, which could in turn be beneficial to farmers.

Determination and biosynthesis of multiple salvianolic acids in hairy roots of Salvia miltiorrhiza.

Danshen (Salvia miltiorrhiza Bunge) hairy roots were obtained by infecting Danshen leaves with Agrobacterium rhizogenes 9402. Besides rosmarinic acid (RA) and salvianolic acid B (SAB), the hairy root could also produce salvianolic acid K (SAK), salvianolic acid L, ethyl salvianolic acid B (ESAB), methyl salvianolic acid B (MSAB), and a compound with a molecular weight of 538 (compound 538) identified by using LC-MS. Effects of methyl jasmonate (MeJA) and yeast elicitor (YE) on the accumulation of these compounds had been investigated. MeJA increased the accumulation of SAB, RA, SAK, and compound 538 from 4.21%, 2.48%, 0.29%, and 0.01% of dry weight to 7.11%, 3.38%, 0.68%, and 0.04%, respectively. YE stimulated the biosynthesis of RA from 2.83% to 5.71%, but depressed the synthesis of SAB, SAK and compound 538. It was indicated in all the results that these Danshen hairy roots could be used as alternative resources to produce salvianolic acids. Analysis of the content variation of these compounds after elicitation suggested that SAK and compound 538 might be the intermediates in the biosynthesis from RA to SAB in Danshen hairy roots.

Expression and characterization of Momordica Chanrantia anti-hyperglycaemic peptide in Escherichia coli.

A nucleic acid sequence MC, encoding Momordica Chanrantia anti-hyperglycaemic peptide MC6 (accession: AAX06814) synthesized according to Escherichia coli preferred codons, was cloned and expressed in E. coli. Recombinant protein pQE8-MC (about 3.5 kDa) was purified and analyzed by 20% SDS-PAGE and western blot. It revealed that the expressed pQE8-MC had good solubility in aqueous media. An HPLC assay was used to confirm the expression of pQE8-MC. Subsequent pharmacological activity assay revealed a significant hypoglycemic effect of low dose treatments of pQE8-MC on male kunming mice. Four hours after an intravenous tail injection, the blood sugar levels of mice treated with pQE8-MC saline solution A3 (1 mg/kg BW) decreased greatly (P < 0.01) relative to the levels of a control group. This suggests that pQE8-MC, expressed in bioengineered E. coli, has a similar hypoglycemic function to the natural protein MC6 from M. Chanrantia. These results reveal the possibility of using bio-engineered bacteria as an anti-diabetic agent.

Effects of calycosin on the impairment of barrier function induced by hypoxia in human umbilical vein endothelial cells.

The purpose of the present study was to examine the effects of calycosin, an isoflavonoid isolated from Astragali Radix, on the impairment of barrier function induced by hypoxia in cultured human umbilical vein endothelial cells. Hypoxia induced an increase in endothelial cell monolayer permeability, indicating endothelial cell barrier impairment. Endothelial barrier dysfunction induced by hypoxia was accompanied by decreases in cytosolic ATP concentration and cAMP level, the development of actin stress fibers and intercellular gap formation, suggesting that the decreases in cytosolic ATP and cAMP levels and rearrangements of F-actin could be associated with an increase in permeability of endothelial monolayers. Application of calycosin inhibited the hypoxia-induced increase in endothelial permeability in a dose-dependent fashion, which is compatible with inhibition of lactate dehydrogenase release, decrease of the fall in ATP and cAMP contents, and improvement of F-actin rearrangements. These findings indicate that calycosin protected endothelial cells from hypoxia-induced barrier impairment by increasing intracellular energetic sources and promoting regeneration of the cAMP level, as well as improving cytoskeleton remodeling.

Effect of astragaloside IV on T, B lymphocyte proliferation and peritoneal macrophage function in mice.

AIM: To investigate the effect of astragaloside IV (ASI) on T, B lymphocyte proliferation, antibody production, and cytokines produced by murine peritoneal macrophages. METHODS: MTT assay was used to determine T, B lymphocyte proliferation and quantitative hemolysin spectrophotometry (QHS) assay was applied to test antibody production; IL-1 production was measured by thymocyte proliferation assay; TNF-alpha production was determined by the cytotoxicity assay against L929 cells. RESULTS: 1) In vivo, ASI 50-200 mg/kg ig for 7 d increased T lymphocyte proliferation and antibody production, and ASI 50-100 mg/kg ig for 7 d increased B lymphocyte proliferation but ASI 200 mg/kg had no effect on B lymphocyte proliferation; 2) In vitro, ASI increased T, B lymphocyte proliferation only at 100 nmol/L; 3) ASI increased IL-1 activity at 1 nmol/L in vitro, but decreased it at 100 and 1000 nmol/L; 4) ASI inhibited TNF-alpha activity with or without LPS-stimulation in vitro. CONCLUSION: ASI increased T, B lymphocyte proliferation and antibody production in vivo and in vitro; but inhibited productions of IL-1 and TNF-alpha from peritoneal macrophages in vitro.

[Effect of components of dang-gui-bu-xue decoction on hematopenia].

OBJECTIVE: To investigate the effects and the related mechanisms of the components of Dang-Gui-Bu-Xue decoction (DGBXD) on improving blood deficiency. METHOD: The effects of promoting hematopoietic function were observed with the blood difficient model mice, by giving components of DGBXD. RBC, WBC, reticulocytes and bone marrow nucleated cells (BMNC) were determined. The components of DGBXD on proliferation of BMNC and on clony forming unit (CFU) were also determined. RESULT: The components of DGBXD remarkably increased the quantity of RBC, WBC, and BMNC. Some of the components promoted the proliferation of BMNC and increased the quantity of CFU-Mix. Among them, polysaccharide of angelica was most potent. CONCLUSION: The studies show that the extracts and some components of DGBXD can promote the hemopoietic function system of the model mice, and they exert the effects in a comprehensive way.

[Effect of Angelica sinensis polysaccharides on lymphocyte proliferation and induction of IFN-gamma].

AIM: To study the effect of Angelica sinsensis polysaccharides on lymphocyte proliferation and induction of IFN-gamma. METHODS: Angelica sinensis polysaccharides(AP) were separated into AP-I, AP-II, AP-III and AP-IV by alcohol deposition with different concentration. The radioactivities of [3H]-TdR uptake by lymphocyte were used to determine the ability of lymphocyte. The bioactivity of IFN-gamma was measured by violet crystalline dying. RESULTS: AP-IV was found to be composed of Ara and Glu in the ratio of 0.99:6.47, the molecular weight was estimated to be 5,600. AP-I and AP-II 100 mg.kg-1 i.p. were found to significantly augment mice splenocyte proliferation, release IFN-gamma and increase IFN-gamma bioactivity. 50 micrograms.mL-1 AP-I, AP-II and AP-III were shown to enhance the proliferative response of the mouse spleen lymphocytes in vitro. CONCLUSION: AP-I and AP-II showed higher immunoactivity than AP-III, AP-IV had no effect.