Anti-hepatitis B virus activities of friedelolactones from Viola diffusa Ging.

BACKGROUND: Hepatitis B virus (HBV) infection is the major factor of causing hepatitis B, cirrhosis and liver cancer. Interferon and nucleoside drugs, the main drugs to treat HBV infection, have disadvantages of scavenge difficulty and drug resistance respectively. Viola diffusa Ging is used as a traditional Chinese herbal medicine for the treatment of hepatitis. PURPOSE: The aim of the study is to investigate the chemical constituents of Viola diffusa Ging and their anti-HBV activity. METHODS: Chemical constituents were extracted and purified by ethanol reflux extraction and chromatographic separation technology including D-101 Macroporous resin, silica gel, Sephadex LH-20 and preparative thin-layer chromatography. Their structures were elucidated on the basis of extensive NMR and MS data. Cytotoxicity and inhibiting effects on HBsAg and HBeAg secretion of HepG2.2.15 of all compounds except 10 were studied by MTT method and ELISA method. RESULTS: Three friedelolactones with naturally occurring seco-ring-A friedelane triterpenoids, 2ß-hydroxy-3, 4-seco-friedelolactone-27-oic acid (1), 2ß, 28ß-dihydroxy-3,4-seco-friedelolactone-27-oic acid (2) and 2ß, 30ß-dihydroxy-3,4-seco-friedelolactone-27-lactone (3), and a stigmastane, stigmast-25-ene-3ß,5α,6ß-triol (11) together with nine known compounds were isolated from the whole plant of Viola diffusa G. (Violaceae). Compounds 1-3, 9, 11, 12 exhibited significant activities of blocking both HBsAg and HBeAg secretion, and compound 4, 6, 7, 8 selectively inhibited HBeAg secretion while compound 13 selectively inhibited HBsAg secretion. IC50 values of compounds 1 and 2, 26.2 µM and 33.7 µM for HBsAg, 8.0 µM and 15.2 µM for HBeAg, was significantly lower than that of positive control lamivudine. CONCLUSION: Compounds 1-3, 11 are new compounds never reported before and the promising results demonstrate the potential of compound 1-3, 9, 11, 12 for the treatment of HBV infection.

Molecularly imprinted polymers on a silica surface for the adsorption of tobacco-specific nitrosamines in mainstream cigarette smoke.

Tobacco-specific nitrosamines are one of the most important groups of carcinogens in tobacco products. Using adsorbents as filter additives is an effective way to reduce tobacco-specific nitrosamines in cigarette smoke. Molecularly imprinted polymers (MIPs) using nicotinamide as template were grafted on the silica gel surface to obtain MIP@SiO2 and employed as filter additives to absorb tobacco-specific nitrosamines in mainstream cigarette smoke. Four milligrams of MIP@SiO2 per cigarette was added to the interface between filter and tobacco rod to prepare a binary filter system. The mainstream smoke was collected on an industry-standard Cambridge filter pad and extracted with ammonium acetate aqueous solution before analysis. Compared to the cigarette smoke of the control group, the levels of tobacco-specific nitrosamines with silica gel and with MIP@SiO2 were both reduced, and the adsorption rates of N-nitrosonornicotine, N-nitrosoanabasine, N-nitrosoanatabine, and 4-(methylnitrosamino)-1-(3-pyridine)-1-butanone with silica gel and with MIP@SiO2 were 20.76, 15.32, 18.79, and 18.01%, and 41.33, 34.04, 37.86, and 35.53%, respectively. Furthermore the content of total particle materials in cigarette smoke with silica gel was decreased evidently but showed no observable change with MIP@SiO2 . It indicated MIP@SiO2 could selectively reduce tobacco-specific nitrosamines in the mainstream cigarette smoke with no change to the cigarette flavor.

Effects of cinnamene enhancers on transdermal delivery of ligustrazine hydrochloride.

Cinnamene compounds, cinnamic acid, cinnamaldehyde and cinnamic alcohol, were employed as enhancers. The effects and mechanisms of penetration promoters on the in vitro percutaneous absorption of ligustrazine hydrochloride across hairless porcine dorsal skin were investigated. Transdermal fluxes of ligustrazine hydrochloride through porcine skin were determined in vitro by Franz-type diffusion cells. The results indicated that the penetration flux of ligustrazine hydrochloride by cinnamic acid was the greatest. Significant statistical differences (P<0.05) were found between cinnamic acid and other promoters. Fourier transform-infrared (FT-IR) were carried out to analyze the effects of enhancers on the biophysical properties of the stratum corneum and the permeation enhancement mechanisms. FT-IR results revealed that the changes of peak shift and peak area due to C-H stretching vibrations in the stratum corneum lipids were associated with the selected enhancers. All of them could perturb and extract the stratum corneum lipids to different extent. Morphological changes of the skin treated with enhancers were monitored by a scanning electron microscope. It was demonstrated that the extraction of the stratum corneum lipids by the enhancers led to the disruption of stratum corneum and the desquamation of stratum corneum flake. Apparent density was newly proposed to estimate the desquamated extent of stratum corneum flake. Correlation analysis revealed that there was a linear relationship between apparent density and decrease in peak area. The results showed that the permeation enhancement mechanisms of cinnamene were pleiotropic ones, including disordering the lipids, extracting the lipids and competitive hydrogen bonding between cinnamene enhancers and amides of ceramide head groups in stratum corneum.

[Removal of the template molecules from vinblastine-imprinted polymer].

OBJECTIVE: To investigate the optimal condition for complete removal of the template molecules from vinblastine (VLB)-imprinted polymer. METHOD: The prepared polymers were packed into the cartridges of solid-phase extraction column and washed by methanol-glacial acetic acid mixture with different proportions. The contents and recoveries of VLB in the effluents were determined. RESULTS: Polymer extraction with methanol-glacial acetic acid (9:1, V/V) resulted in VLB recovery of 91.73%, but template bleeding was observed because of incomplete VLB removal. Using methanol-glacial acetic acid (6:4, V/V) as the extraction solvent, the recovery of VLB reached 98.03% with less solvents and extract times. The polymers could selectively adsorb VLB through non-covalent interactions and still exhibited strong affinity for the template molecule but not for the structural analogue vincristine after extraction with methanol-glacial acetic acid (6:4, V/V). CONCLUSION: Methanol-glacial acetic acid (6:4, V/V) is an ideal extract solvent for complete template molecule removal from the polymers, and the processed polymers possess stable capacity of specific recognition and selectivity to the template.

Investigation of imprinting parameters and their recognition nature for quinine-molecularly imprinted polymers.

A series of molecularly imprinted polymers (MIPs) was prepared using quinine as the template molecules by bulk polymerization. The presence of monomer-template solution complexes in non-covalent MIPs systems has been verified by both fluorescence and UV-vis spectrometric detection. The influence of different synthetic conditions (porogen, functional monomer, cross-linkers, initiation methods, monomer-template ratio, etc.) on recognition properties of the polymers was investigated. Scatchard analysis revealed that two classes of binding sites were formed in the imprinted polymer. The corresponding dissociation constants were estimated to be 45.00 micromol l(-1) and 1.42 mmol l(-1), respectively, by utilizing a multi-site recognition model. The binding characteristics of the imprinted polymers were explored in various solvents using equilibrium binding experiments. In the organic media, results suggested that polar interactions (hydrogen bonding, ionic interactions, etc.) between acidic monomer/polymer and template molecules were mainly responsible for the recognition, whereas in aqueous media, hydrophobic interactions had a remarkable non-specific contribution to the overall binding. The specificity of MIP was evaluated by rebinding the other structurally similar compounds. The results indicated that the imprinted polymers exhibited an excellent stereo-selectivity toward quinine.

[Optimization of the polymerization conditions of vinblastine imprinted polymer by uniform design].

OBJECTIVE: To optimize the polymerization conditions of vinblastine (VLB) imprinted polymer. METHODS: The conditions were optimized by the method of uniform design. The major factors investigated included the amount of functional monomer (MAA) and the cross-linker (EDMA) and the progenic solvent (toluene or acetonitril). The adsorption rate of VLB on the solid-phase extraction (SPE) column packed with MIP was adopted as the response value. RESULTS: The optimal conditions were MAA 0.4 mmol, EDMA 1.6 mmol and using acetonitrile as the solvent. Under the conditions,the VLB imprinted polymer was synthesized and the absorption rate of VLB was 88.20%. The characterizations of the optimal MIP were determined by IR spectrometry and scanning electron microscope (SEM) analysis. CONCLUSION: It is possible to furtherly improve the nature of the polymer by optimizing the polymerization parameters with uniform design. The polymer synthesized under the optimal conditions exhibited high affinity to the target molecule VLB.

[Mechanism of quercetin as an antidiarrheal agent].

OBJECTIVE: To investigate the antidiarrheal mechanism of quercetin extracted from Psidium guajava L. METHODS: The effects of quercetin on the contractility of guinea pig ileum in vitro and on the peristaltic motion of mouse small intestine in vivo were observed, and the peak value of contractility and peristaltic distance recorded. The inhibitory effect of quercetin on the permeability of the abdominal capillaries was also observed. RESULTS: Quercetin inhibited the contraction of guinea pig ileum in vitro and the peristaltic motion of mouse small intestine, and reduced the permeability of abdominal capillaries. CONCLUSION: Quercetin can inhibit the intestinal movement and reduce capillary permeability in the abdominal cavity, which may be the antidiarrheal mechanism of Psidium guajava L extract.