Excavation of lead compounds that inhibit mast cell degranulation by combinatorial chemistry and activity-guided

An allergic reaction ensues after antigen binds to mast cell or basophil high affinity IgE receptor, Fc epsilonRI, resulting in degranulation of various inflammatory mediators that produce various allergic symptoms. In this study, i) we isolated the active component for the inhibition of mast cell degranulation from the extract of leaves of Castanea crenata and identified it as quercetin; ii) we established the total synthesis procedure of quercetin; iii) using quercetin as positive control, we excavated some lead compounds that possess inhibitory activities for mast cell degranulation by screening the chemical libraries of 1,3-oxazolidine derivatives prepared by solid phase combinatorial chemistry. Some of 1,3-oxazolidine compounds possessing acetyl and 3',4'-dichlorophenyl group displayed strong inhibitory activities on Fc epsilonRI-mediated mast cell degranulation, suggesting that they can be used as lead compounds for the development of anti-allergic agents.     

Triterpenoids from the leaves of Diospyros kaki (persimmon) and their inhibitory effects on protein tyrosine phosphatase 1B

Phytochemical study on a methanol-soluble extract of the leaves of persimmon (Diospyros kaki) resulted in the isolation of two new ursane-type triterpenoids, 3alpha,19alpha-dihydroxyurs-12,20(30)-dien-24,28-dioic acid (1) and 3alpha,19alpha-dihydroxyurs-12-en-24,28-dioic acid (2), together with 12 known ursane- and oleanane-type triterpenoids (3-14). Triterpenoids with a 3beta-hydroxy group were found to inhibit protein tyrosine phosphatase 1B (PTP1B) activity, with IC50 values ranging from 3.1+/-0.2 to 18.8+/-1.3 microM, whereas those with a 3alpha-hydroxy moiety were not active.     

Scalarane sesterterpenes from the sponge Smenospongia sp

Ten new sesterterpene compounds (4-13) and seven known metabolites (1-3, 14-17) were isolated from the sponge Smenospongia sp. collected from Korean coastal waters. On the basis of combined spectroscopic analyses, the new compounds exhibited diverse functionalities on a common scalarane sesterterpene structure. The presence of a 23-aldehyde on compound 6 and a 20-carboxylic acid on 11 is unprecedented among sponge-derived scalarane sesterterpenes. Several of the new compounds showed significant cytotoxicity and antimicrobial activity, as well as moderate inhibitory activity against isocitrate lyase.     

Comparison between ethanolic and aqueous extracts from Chinese juniper berries for hypoglycaemic and hypolipidemic effects in alloxan-induced diabetic rats

AIM OF THE STUDY: Hypoglycaemic and hypolipidemic properties of the ethanolic and aqueous extracts, respectively, from Chinese juniper (Juniperus chinensis L.) berries were investigated in alloxan-induced diabetic rats. MATERIALS AND METHODS: After oral administration of each extract singly or repeatedly to alloxan-induced diabetic rats, the blood glucose, glutamate-pyruvate transferase (GPT), glutamate-oxaloacetate transaminase (GOT), total cholesterol (TC) and triglyceride (TG) levels were assayed. RESULTS: The blood glucose levels after a single oral administration of the ethanolic extract significantly reduced in a time-dependent manner, which is much faster and more than that of glibenclamide. The blood glucose levels of alloxan-induced diabetic rats treated with the ethanolic extract were reduced to 94, 81%, 66%, 45% and 40% at 1, 3, 5, 7 and 9h, respectively (p<0.05), while the aqueous extract had no effect at all. Repeated oral administration of the ethanolic extract also effectively reduced the GPT value to 58% of the diabetic rats, but slightly reduced the GOT value to 87% of the diabetic rats (p<0.05). On the other hand, the repeated oral administration of aqueous extract effectively reduced the GOT value to 43% of the diabetic rats, without affecting the GPT level. Effects of both extracts on the TC and TG levels were different. There was no significant difference in the TC and TG levels between diabetic control and diabetic groups when repeatedly administered orally with ethanolic extract. On the other hand, the aqueous extract brought down the TC value to 57% and the TG value to 37% of the diabetic control rats (p<0.05). CONCLUSIONS: The results suggested that the ethanolic extract of Chinese juniper berries possesses a potential hypoglycaemic effect while the aqueous extract has a potential hypolipidemic effect.     

Toxicity of Citrate-Coated Silver Nanoparticles Differs According to Method of Suspension Preparation

To evaluate substance toxicity, it is critical to maintain specific concentrations of test substances throughout the exposure period. During the last decade, the need to improve methods for nanoparticle (NP) suspension preparations has gained attention because many published results on NPs toxicity have been inconsistent. Here, we compared the toxicity of citrate-coated silver nanoparticles (AgNPs) suspended by two different methods (fractionated vs. colloidal) in freshwater organisms (daphnia and medaka). Analytical methods (ICP-OES, DLS and UV absorbance) were employed to characterize behavior of AgNPs in suspension. Results showed that fractionated (stirred and settled) solution was less toxic to daphnia (13.8 µg/L) than colloidal solution (6.1 µg/L), suggesting that method of preparation was a critical factor that affected toxicity. However, differences in toxicity caused by suspension methods were not observed in medaka. Results indicate that the method used to prepare suspensions of NPs can affect toxicity, and that differences can exist among test organisms.     

Fabrication of Large-Area Mullite–Cordierite Composite Substrates for Semiconductor Probe Cards and Enhancement of Their Reliability

This work aims to fabricate a large-area ceramic substrate for the application of probe cards. Mullite (M) and cordierite (C), which both have a low thermal expansion coefficient, excellent resistance to thermal shock, and high durability, were selected as starting powders. The mullite–cordierite composites were produced through different composition ratios of starting powders (M:C = 100:0, M:C = 90:10, M:C = 70:30, M:C = 50:50, M:C = 30:70, and M:C = 0:100). The effects of composition ratio and sintering temperature on the density, porosity, thermal expansion coefficient, and flexural strength of the mullite–cordierite composite pellets were investigated. The results showed that the mullite–cordierite composite pellet containing 70 wt% mullite and 30 wt% cordierite sintered at 1350 °C performed exceptionally well. Based on these findings, a large-area mullite–cordierite composite substrate with a diameter of 320 mm for use in semiconductor probe cards was successfully fabricated. Additionally, the changes in sheet resistance and flexural strength were measured to determine the effect of the environmental tests on the large-area substrate such as damp heat and thermal shock. The results indicated that the mullite–cordierite composite substrate was extremely reliable and durable.