Antidiabetic properties and mechanism of action of Gynura procumbens water extract in streptozotocin-induced diabetic rats

Gynura procumbens (Lour.) Merr (family Compositae) is cultivated in Southeast Asia, especially Indonesia, Malaysia and Thailand, for medicinal purposes. This study evaluated the in vivo hypoglycemic properties of the water extract of G. procumbens following 14 days of treatment and in vitro in RIN-5F cells. Glucose absorption from the intestines and its glucose uptake in abdominal skeletal muscle were assessed. The antidiabetic effect of water extract of G. procumbens leaves was investigated in streptozotocin-induced diabetic rats. The intraperitoneal glucose tolerance test (IPGTT) was performed in diabetic rats treated with G. procumbens water extract for 14 days. In the IPGTT, blood was collected for insulin and blood glucose measurement. After the IPGTT, the pancreases were collected for immunohistochemical study of β-cells of the islets of Langerhans. The possible antidiabetic mechanisms of G. procumbens were assessed through in vitro RIN-5F cell study, intestinal glucose absorption and glucose uptake by muscle. The results showed that G. procumbens significantly decreased blood glucose levels after 14 days of treatment and improved outcome of the IPGTT. However, G. procumbens did not show a significant effect on insulin level either in the in vivo test or the in vitro RIN-5F cell culture study. G. procumbens also showed minimal effects on β-cells of the islets of Langerhans in the pancreas. However, G. procumbens only significantly increased glucose uptake by muscle tissues. From the findings we can conclude that G. procumbens water extract exerted its hypoglycemic effect by promoting glucose uptake by muscles.     

A proteomic approach based on multiple parallel separation for the unambiguous identification of an antibody cognate antigen

Autoantibodies obtained from cancer patients have been identified as useful tools for cancer diagnostics, prognostics, and as potential targets for immunotherapy. Serological proteome analysis in combination with 2‐DE is a classic strategy for identification of tumor‐associated antigens in the serum of cancer patients. However, serological proteome analysis cannot always indicate the true antigen out of a complex proteome identified from a single protein spot because the most abundant protein is not always the most antigenic. To address this problem, we utilized multiple parallel separation (MPS) for proteome separation. The common identities present in the fractions obtained using different separation methods were regarded as the true antigens. The merit of our MPS technique was validated using anti‐ARPC2 and anti‐PTEN antibodies. Next, we applied the MPS technique for the identification of glycyl‐tRNA synthetase as the cognate antigen for an autoantibody that was overexpressed in the plasma of breast cancer patients. These results reveal that MPS can unambiguously identify an antibody cognate antigen by reducing false‐positives. Therefore, MPS could be used for the characterization of diagnostic antibodies raised in laboratory animals as well as autoantibodies isolated from diseased patients.     

Performance of ionic liquid as catalyst in the copolymerization of phenyl glycidyl ether with carbon dioxide

Summary Selective ammoxidation of ethylene over Co-ZSM-5 prepared by aqueous and solid-state ion exchange has been studied. The catalyst prepared using solid-state exchange showed higher activity and selectivity to acetonitrile. Catalysts tested in the ammoxidation of ethylene were previously characterized by chemical analysis, XRD, N₂-BET measurements and FTIR. TPD of ammonia and FTIR of pyridine used as probe molecule showed that solid-state ion exchange of H-ZSM-5 with cobalt generates new Lewis acid sites which seem to play a role in the ammoxidation reaction.     

Synthesis of 2,3-disubstituted indole on solid phase by the Fischer indole synthesis

2,3-Disubstituted indoles were synthesized by solid-phase reaction using the Fischer indole synthesis. A "traceless" silicon linker was employed with the silicon-carbon bonding being cleaved with TFA. An oxygen atom was placed into the middle of the spacer/linker so as to enhance solid-phase synthesis by better solvation.     

Angustilodine,an Unusual Pentacyclic Indole Alkaloid from Alstonia

Two new indole alkaloids, angustilodine ( 1 ), with an unprecedented pentacyclic carbon skeleton, and angustilocine ( 2 ), belonging to the seco‐angustilobine‐B group of alkaloids, were obtained from the leaf extract of the Malayan species Alstonia angustiloba, and their structures were established by spectroscopic analysis.     

Interpolymer complexes of copolymers of vinyl ether of diethylene glycol with poly(acrylic acid)

 The complex formation reactions of poly(vinyl ether of diethylene glycol) as well as vinyl ether of diethylene glycol–vinyl butyl ether copolymers with poly(acrylic acid) have been studied in aqueous and alcohol solutions. The formation of interpolymer complexes which were stabilized by hydrogen bonds was shown. The effects of molecular weight of poly(acrylic acid) and the nature of the nonionic polymer on the composition and stability of interpolymer complexes were clarified. The critical pH values of complexation were determined for different systems with various molecular weights and hydrophobic–hydrophilic balances. The stability of the interpolymer complexes formed in aqueous and alcohol solutions with respect to dimethylformamide addition was evaluated. The role of hydrophobic interactions and the presence of active groups on stability of the interpolymer complexes is discussed. Received: 23 July 2001 Accepted: 27 September 2001     

Synthesis and Characterization of Silica Aerogel-Polymer Hybrid Materials

Abstract

Silica aerogel-based hybrid composites containing three different polymers such as poly(styrene) (PS), poly(methyl methacrylate) (PMMA), and PS-co-PMMA were synthesized by two steps: sol-gel reaction to form vinyl silica aerogels and radical polymerization to combine the silica aerogels with the polymers. The reactions were confirmed using FTIR and FE-SEM, showing successful polymerization in the surface of the silica aerogel network. Incorporation of the polymers into the silica aerogel allows for the enhancement of thermal stabilities. From dielectric measurement, the polymer hybridization leads to an increase in the static dielectric constant, compared to bare silica aerogel.     

Collapse of Poly(methacrylic acid) Hydrogels in Response to Simultaneous Stimulation by an Electric Field and Complex Formation

Complex formation of poly(methacrylic acid) hydrogels with linear poly(ethylene glycol) has been studied at different pH values and in the presence of an electric field. The fastest contraction of the gel samples was observed under simultaneous action of electric field and complex formation.

Dependence of the volume ratio V/V₀ of PMAA sample on time: Sample in the absence of an electric field immersed in 0.1 M PEG solution at (1) pH 8.2, (2) at pH 5.1, and in the presence of an electric field (3) in water and (4) 0.1 M PEG solution at pH 5.1.     

Temperature-responsive swelling and deswelling of the copolymers from vinyl ether of ethylene glycol and butyl vinyl ether

Linear and crosslinked copolymers of a vinyl ether of ethylene glycol (2-hydroxyethyl vinyl ether, ( 1 )) and butyl vinyl ether ( 2 ) are synthesized by α-irradiation polymerization. It is shown that the linear copolymers exhibit a phase separation phenomenon in dependence of the temperature due to the destruction of hydrogen bonds and the enhancement of hydrophobic interaction in aqueous solution. The processes of reversible swelling or shrinking upon temperature change are demonstrated for polymer networks.