Triterpenoids isolated from Ganoderma lucidum (GLTs) exhibit a broad spectrum of anti-cancer properties, including anti-proliferative, anti-metastatic and anti-angiogenic activities. Current research studies revealed the role by GLTs in inducing apoptosis and suppression of telomerase activity of cancer cells with much lower toxicity to healthy cells. Compounds selectively binding and stabilizing G-quadruplex structures could inhibit the telomerase or downregulate the oncogenes and may act as anti-cancer agents. Targeting human telomeric G-quadruplex DNA could be one of the mechanisms by which these GLTs exert anti-cancer activity. In this study, 208 GLTs were screened for ligands with high binding affinity and selectively to stabilize the pG4DNA by using the docking tool AutoDock4. The results showed that ganoderic acid A and ganoderic acid Df exhibit high binding affinity and selectively bind to the lateral groove of pG4DNA. Based on our findings, we suggest that the triterpenoid represents a new class of G-quadruplex groove binding ligands and thus act as potential anti-cancer agents.

Oxidation of low density lipoprotein (LDL) has been postulated as the main cause of atherogenesis, resulting in formation of foam cells, triggering of various pathways, and leading to the development of the disease. Therefore, antioxidants would naturally be expected to attenuate the progress of atherosclerosis. α-Tocopherol (α-TocH) is the most abundant form of vitamin E in nature and the major antioxidant of biological membranes. α-TocH is also present at a much higher concentration than other antioxidants in plasma lipoproteins. The large amount of α-TocH present in LDL leads to the expectation that lipid peroxidation would be strongly inhibited by α-TocH. However, advanced atherosclerotic plaques are not deficient in the presence of antioxidants such as vitamins C and E, despite the occurrence of massive lipid oxidation. Thus conventional mechanism associated with the antioxidant properties of α-TocH cannot explain why lipid peroxidation occurs in atherosclerotic lesions in the presence of compounds that are usually considered to be antioxidants. A kinetic model was developed and applied to explore the mechanism of lipid peroxidation process under various conditions and to examine the possible occurrence of lipid peroxidation in the presence of α-tocopherol. The model incorporated many factors, that were not included in previous models but we believe to play important roles in the different outcome of the process. As a result, the numerical simulation illustrated that lipid peroxidation in the lipoprotein particle could occur in the presence of vitamins E (α-TocH) and C under certain conditions, including high initiation rate, high initial α-TocH level, low ratio of [vitamin C]/[α-TocH], and small lipoprotein particles. The kinetic scheme developed in this study defined the type of relationship that α-TocH in an environment exhibits either pro-or antioxidative property. Thus, antioxidant and pro-oxidant effects of tocopherol merely depend on the condition in which its properties are exhibited.

CRM197 is a diphtheria toxin (DT) mutant (G52E) which has been used as a carrier protein for conjugate vaccines. However, it still possesses cytotoxicity toward mammalian cells. The goal of this project was to produce a non-toxic and soluble CRM197EK through introduction of triple amino acid substitutions (K51E/G52E/E148K) in Escherichia coli. The expression of CRM197EKTrxHis was optimized and co-expressed with different molecular chaperones. The soluble CRM197EKTrxHis was produced at a high concentration (97.33 ± 17.47 μg/ml) under the optimal condition (induction with 0.1 mM IPTG at 20 °C for 24 h). Cells containing pG-Tf2, expressing trigger factor and GroEL-GroES, accumulated the highest amount of soluble CRM197EKTrxHis at 111.24 ± 10.40 μg/ml after induction for 24 h at 20 °C. The soluble CRM197EKTrxHis still possesses nuclease activity and completely digest λDNA at 25 and 37 °C with 8- and 4-h incubation, respectively. Molecular modeling of diphtheria toxin, CRM197 and CRM197EK indicated that substitutions of two amino acids (K51E/E148K) may cause poor NAD binding, consistent with the lack of toxicity. Therefore, CRM197EK might be used as a new potential carrier protein. However, further in vivo study is required to confirm its roles as functional carrier protein in conjugate vaccines.

ObjectiveTo study the association of the butyrylcholinesterase K variant (BChE-K) and the plasma BChE activity with mild cognitive impairment (MCI) in Thai community-dwelling patients.MethodsOne hundred patients diagnosed with MCI and 100 control subjects were recruited from the community-dwelling setting in Bangkok, Thailand. The genotype and allele distributions of the BChE-K were determined by polymerase chain reaction and subsequent DNA sequencing. The BChE activity was measured in plasma according to the Ellman’s method.ResultsThe BChE-K allele frequencies in the Thai community-dwelling patients were in accordance with other ethnics. The BChE-K allele frequency in the control subjects (12%) was higher than that of MCI patients (5.5%), suggesting a protective role of BChE-K for MCI in the Thai community-dwelling patients. The BChE-K homozygotes were significantly associated with lower BChE activity.ConclusionOur results suggested that the BChE-K may be implicated as a protective factor for MCI in the Thai community-dwelling patients, although a further study with a large sample size is warranted to confirm this.

Alzheimer’s disease (AD) is a major public health problem worldwide due to an increase in the elderly population. The current pharmacotherapy for the early stages of AD is mainly dependent on cholinesterase inhibitors. Two of the most commonly used anti-AD drugs, donepezil (DPZ) and galantamine (GLM), are selective inhibitors for human acetylcholinesterase (hAChE). However, the inhibitory activity of DPZ on hAChE was more potent than GLM by ~85 times. To better understand the molecular basis for differences in mode of inhibition of hAChE by both drugs, molecular dynamics (MD) simulation was performed. The results showed that the active site residues of hAChE/DPZ had the higher hydrogen bond occupancies as compared to hAChE/GLM. Nevertheless, the 2 drugs directly formed hydrogen bonds with the catalytic residue H447 of hAChE. The per-residue free energy decomposition suggested that DPZ interacted with the residues in peripheral anionic site of hAChE, resulting in the greater binding affinity of DPZ than that of GLM toward hAChE. The binding free energy calculation based on MM-PBSA and MM-GBSA methods indicated that van der Waal interactions played a predominant role as the driving force for binding process of DPZ and GLM to hAChE. Moreover, the predicted total binding free energy of hAChE/DPZ was stronger than hAChE/GLM, which was consistent well with the experimental data. We hope that our findings provide useful information for further design of novel hAChE inhibitors. HIGHLIGHTS Anti-Alzheimer’s drugs donepezil and galantamine in complex with human acetylcholinesterase were explored by MD simulations and binding free energy calculations The MM-PB(GB)SA-based binding free energy indicated that donepezil exhibited a more favorable binding affinity to human acetylcholinesterase than galantamine The molecular rotation of galantamine during MD simulation resulted in the reduction of hydrogen bond occupancies with D74 and S203 The van der Waals interactions were considered as the major contributor to the binding of both drugs GRAPHICAL ABSTRACT