Menthol Binding and Inhibition of α7-Nicotinic Acetylcholine Receptors

Menthol is a common compound in pharmaceutical and commercial products and a popular additive to cigarettes. The molecular targets of menthol remain poorly defined. In this study we show an effect of menthol on the α₇ subunit of the nicotinic acetylcholine (nACh) receptor function. Using a two-electrode voltage-clamp technique, menthol was found to reversibly inhibit α7-nACh receptors heterologously expressed in Xenopus oocytes. Inhibition by menthol was not dependent on the membrane potential and did not involve endogenous Ca²⁺-dependent Cl⁻ channels, since menthol inhibition remained unchanged by intracellular injection of the Ca²⁺ chelator BAPTA and perfusion with Ca²⁺-free bathing solution containing Ba²⁺. Furthermore, increasing ACh concentrations did not reverse menthol inhibition and the specific binding of [¹²⁵I] α-bungarotoxin was not attenuated by menthol. Studies of α₇- nACh receptors endogenously expressed in neural cells demonstrate that menthol attenuates α₇ mediated Ca²⁺ transients in the cell body and neurite. In conclusion, our results suggest that menthol inhibits α7-nACh receptors in a noncompetitive manner.     

Inhibitory effects of estrogens on digestive enzymes,insulin deficiency,and pancreas toxicity in diabetic rats

Diabetes mellitus, with its attendant disorders and dysfunctional behaviors, constitutes a growing concern to the population of the world. With this concern in mind, the present study investigated the anti-diabetic and hypolipedimic potential of 17β-estradiol (called E2), particularly in terms of its inhibitory effects on maltase, sucrase, lactase, and lipase activities in the intestine of surviving diabetic rats. The findings revealed that this supplement helped protect the β cells of the rats from death and damage. Interestingly, E2 induced considerable decreases of 29%, 46%, 42%, and 84% in the activities of intestinal maltase, lactase, sucrase, and lipase, respectively. The E2 extract also decreased the glucose, triglyceride, and total cholesterol rates in the plasma of diabetic rats by 39%, 27%, and 53%, respectively, and increased the HDL–cholesterol level by 74%, which helped maintain the homeostasis of blood lipid. When compared to those of the untreated diabetic rats, the superoxide dismutase, catalase, and glutathione peroxidase levels in the pancreas of the rats treated with this supplement were also enhanced by 330%, 170%, and 301%, respectively. A significant decrease was also observed in the lipid peroxidation level and lactate dehydrogenase activity in the pancreas of diabetic rats after E2 administration. Overall, the findings presented in this study demonstrate that E2 has both a promising potential with regard to the inhibition of intestinal maltase, sucrase, lactase, and lipase activities, and a valuable hypoglycemic and hypolipidemic function, which make it a potential strong candidate for industrial application as apharmacological agent for the treatment and prevention of hyperlipidemia, obesity, and cardiovascular diseases.     

Segmented linear modeling of CHO fed‐batch culture and its application to large scale production

We describe a systematic approach to model CHO metabolism during biopharmaceutical production across a wide range of cell culture conditions. To this end, we applied the metabolic steady state concept. We analyzed and modeled the production rates of metabolites as a function of the specific growth rate. First, the total number of metabolic steady state phases and the location of the breakpoints were determined by recursive partitioning. For this, the smoothed derivative of the metabolic rates with respect to the growth rate were used followed by hierarchical clustering of the obtained partition. We then applied a piecewise regression to the metabolic rates with the previously determined number of phases. This allowed identifying the growth rates at which the cells underwent a metabolic shift. The resulting model with piecewise linear relationships between metabolic rates and the growth rate did well describe cellular metabolism in the fed‐batch cultures. Using the model structure and parameter values from a small‐scale cell culture (2 L) training dataset, it was possible to predict metabolic rates of new fed‐batch cultures just using the experimental specific growth rates. Such prediction was successful both at the laboratory scale with 2 L bioreactors but also at the production scale of 2000 L. This type of modeling provides a flexible framework to set a solid foundation for metabolic flux analysis and mechanistic type of modeling. Biotechnol. Bioeng. 2017;114: 785–797. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.     

New Specific α-Glucosidase Inhibitor Flavonoid from Thymelaea tartonraira Leaves: Structure Elucidation,Biological and Molecular Docking Studies

The phytochemical investigation of Thymelaea tartonraira leaves led to the isolation and characterization of six compounds, including one new flavonoid glycoside identified as hypolaetin 8-O-β-D-galactopyranoside ( 4 ) along with five known compounds, daphnoretin ( 1 ), triumbelletin ( 2 ), genkwanin ( 3 ), tiliroside ( 5 ) and yuankanin ( 6 ). Their structures were established based on spectroscopic methods, such as UV, IR, NMR, and HR-ESI-MS. Triumbelletin ( 2 ) and tiliroside ( 5 ) were isolated for the first time from T. tartonraira leaves. The antioxidant property of all isolated compounds was tested based on DPPH, FRAP and total antioxidant capacity assays. Compound 4 displayed an antioxidant potency more interesting than vitamin C with an IC₅₀=15.00±0.50 μg/ml, followed by compound 5 . Furthermore, the both compounds 4 and 5 were tested for their α-amylase inhibitory activity in-vitro. Compound 4 displayed higher potency to inhibit α-amylase, with an IC₅₀=46.49±2.32 μg/ml, than compound 5 , with an IC₅₀=184.2±9.2 μg/ml, while the reference compound acarbose presented the highest potency to inhibit α-amylase with an IC₅₀=0.44±0.022 μg/ml. Compound 4 displayed a strong inhibitory ability of α-glucosidase activity approximately twice more than the reference compound, acarbose, with IC₅₀ values of 60.00±3.00 and 125.00±6.25 μg/ml, respectively. Thus, compound 4 exhibited a specific inhibitory activity for α-glucosidase. The molecular docking studies have supported our findings and suggested that compound 4 has been involved in various binding interactions within the active site of both enzymes α-amylase and α-glucosidase.     

The Drosophila fragile X mental retardation protein controls actin dynamics by directly regulating profilin in the brain

Loss of Fragile X mental retardation protein (FMRP) function causes the highly prevalent Fragile X syndrome [1 and 2]. Identifying targets for the RNA binding FMRP is a major challenge and an important goal of research into the pathology of the disease. Perturbations in neuronal development and circadian behavior are seen in Drosophila dfmr1 mutants. Here we show that regulation of the actin cytoskeleton is under dFMRP control. dFMRP binds the mRNA of the Drosophila profilin homolog and negatively regulates Profilin protein expression. An increase in Profilin mimics the phenotype of dfmr1 mutants. Conversely, decreasing Profilin levels suppresses dfmr1 phenotypes. These data place a new emphasis on actin misregulation as a major problem in fmr1 mutant neurons.     

The regulation of RhoA at focal adhesions by StarD13 is important for astrocytoma cell motility

Malignant astrocytomas are highly invasive into adjacent and distant regions of the normal brain. Rho GTPases are small monomeric G proteins that play important roles in cytoskeleton rearrangement, cell motility, and tumor invasion. In the present study, we show that the knock down of StarD13, a GTPase activating protein (GAP) for RhoA and Cdc42, inhibits astrocytoma cell migration through modulating focal adhesion dynamics and cell adhesion. This effect is mediated by the resulting constitutive activation of RhoA and the subsequent indirect inhibition of Rac. Using Total Internal Reflection Fluorescence (TIRF)-based Förster Resonance Energy Transfer (FRET), we show that RhoA activity localizes with focal adhesions at the basal surface of astrocytoma cells. Moreover, the knock down of StarD13 inhibits the cycling of RhoA activation at the rear edge of cells, which makes them defective in retracting their tail. This study highlights the importance of the regulation of RhoA activity in focal adhesions of astrocytoma cells and establishes StarD13 as a GAP playing a major role in this process.     

Screening of natural products for therapeutic activity against solid tumors

Most of the currently used cancer therapeutics are natural products. These agents were generally discovered based on their toxicity to tumour cells using various bioassays. Although the exact mechanisms of action of the most commonly used cancer therapeutics such as anthracyclins, podophyllotoxins and camptothecin are incompletely understood, it is becoming increasingly clear that these agents often show complex modes of action at the cellular level, interacting with numerous targets. Such complex modes of action may be the very reason for clinical efficacy. For discovering new cytotoxic anticancer drugs sophisticated screening methods were used. The principles of such screening projects conducted, using collections of purified natural products or extracts from plants have been described. By performing simple but robust prescreening tests such as the brine shrimp assay, bioactive extracts can be identified. Extracts (65) prepared from a collection of Egyptian plants were identified that showed cytotoxity on HepG2 cells. Interestingly, 22 (33%) of these raw extracts, induced > 2-fold induction of caspase-cleavage activity in a colon carcinoma cell line, consistent with induction of apoptosis. Only a fraction of the diversity of the biosphere has been tested for biological activity and novel cancer therapeutics remains to be discovered.     

Modulatory effects of hard clam (Mercenaria mercenaria) tissue extracts on the in vitro growth of its pathogen QPX

Quahog parasite unknown (QPX) is a fatal protistan parasite affecting cultured and wild hard clams Mercenaria mercenaria along the northeastern coasts of the USA and maritime Canada. Field investigations and laboratory transmission studies revealed some variations in the susceptibility of different hard clam stocks to QPX infection. In this study, we used in vitro QPX cultures to investigate the effect of plasma and tissue extracts from two different clam stocks on parasite survival and growth. Results demonstrated the presence of factors in clams that significantly modulate QPX growth. Extracts from gills and mantle tissues as well as plasma inhibited in vitro QPX growth, whereas foot and adductor muscle extracts enhanced parasite growth. Investigations of anti-QPX activities in plasma from two clam stocks displaying different susceptibility toward QPX disease in vivo demonstrated higher inhibition of QPX growth by plasma from New York (resistant) clams compared to Florida (susceptible) clams. Some clams appeared to be deficient in inhibitory factors, suggesting that such animals may become more easily infected by the parasite.