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[Display omitted] • Over 40 metabolites were detected in G. lucidum extracts. Notably, we identified previously unreported metabolites. • Most metabolite contents increased rapidly from period I to II. Following this, they decreased until reaching period VII. • The optimal time to harvest G. lucidum is during period IV. • Cytochrome P450 genes GlCYP1 , GlCYP3 , GlCYP5 , GlCYP6 and GlCYP13 may have critical roles in the biosynthesis of GAs. Ganoderma lucidum (G. lucidum) is a rare medicinal fungus with various beneficial properties. One of its main components, ganoderic acids (GAs), are important triterpenoids known for their sedative and analgesic, hepatoprotective, and anti-tumor activities. Understanding the growth and development of the G. lucidum fruiting body is crucial for determining the optimal time to harvest them. In this study, we used nuclear magnetic resonance (NMR) spectroscopy to systematically characterize the metabolites of G. lucidum at seven distinct developmental stages. We also measured the contents of seven kinds of GAs using LC-MS/MS. A total of 49 metabolites were detected in G. lucidum , including amino acids, sugars, organic acids and GAs. During the transition from the bud development period (I) to the budding period (II), we observed a rapid accumulation of glucose, tyrosine, nicotinamide ribotide, inosine and GAs. After the budding period, the contents of most metabolites decreased until the mature period (VII). In addition, the contents of GAs showed an initial raising, followed by a decline during the elongation period, except for GAF, which exhibited a rapid raise during the mature stage. We also detected the expression of several genes involved in GA synthesis, finding that most genes including 16 cytochrome P450 monooxygenase were all down-regulated during periods IV and VII compared to period I. These findings provide valuable insights into the dynamic metabolic profiles of G. lucidum throughout its growth stage, and it is recommended to harvest G. lucidum at period IV. [ABSTRACT FROM AUTHOR]

Abstract: It has been well accepted that the double quantum (DQ) correlated-spectroscopy revamped by asymmetric z-gradient echo detection (CRAZED) signal is enveloped in the profile function t 2 exp[−(t 2 +2t 1)/T 2], but this function is too simple to describe the spin echo characteristics of the CRAZED free induction decay signal. In this paper the DQ CRAZED experiment is analyzed by including the homogeneous and inhomogeneous broadening effects, and a formula for the time domain DQ CRAZED signal is obtained. This formula includes the chemical shift echo and the inhomogeneous echo, both appearing at t 2 =2t 1. Experiments have confirmed the theory. [Copyright &y& Elsevier]

The effect of acetonitrile (ACN) on the low-affinity interaction between human serum albumin (HSA) and ibuprofen (IBP) was studied using 1H-NMR techniques. Both chemical shift and relaxation measurements showed the addition of ACN to the solutions decreased the binding affinity of IBP to HSA and reduced the hydrophobic interaction between them. The self-diffusion coefficients of IBP were measured as a function of the drug concentration at different ACN concentrations. The association constant, Ka, for ligand–HSA complexes and the number of binding sites, n, are evaluated by the application of Langmuir isotherm. The results indicated that the value of n was about 38 without ACN, and about 26 with ACN concentration 12% (v/v%). The decreased binding capacity of IBP to HSA in the presence of ACN was mainly attributed to the competition of ACN with IBP to the low-affinity binding sites of HSA molecule. [Copyright &y& Elsevier]

Abstract: The metabolic changes in hippocampus, temporal cortex and prefrontal cortex in SD rats along with aging were explored using a metabonomic approach, which based on high resolution “magic angle spinning”1H NMR spectroscopy. The metabolite profiles were analyzed by partial least squares-discriminant analysis, and the results showed that the metabolites of the above three brain regions in old rats were dramatically different from that in the adult and young rats. The old rats showed increased myo-inositol and lactate in all of the three brain regions, and decreased N-acetylaspartate in temporal and frontal cortex, Glutamate–GABA level became imbalance in temporal cortex of old rats. In addition, compared with the adult female rats, male rats had higher levels of N-acetylaspartate, taurine, and creatine in temporal or frontal cortex. The age-related metabolic changes may indicate the early functional alterations of neural cells in these brain regions, especially the temporal cortex. The gender-related metabolic changes suggest the significance of the hormonal regulation in brain metabolism. Our work highlights the potential of metabolic profiling to enhance our understanding of biological mechanisms of brain aging. [Copyright &y& Elsevier]

Abstract: Directly coupled HPLC-NMR has become a powerful tool for separation and structural elucidation of unknown compounds. However, there are only a few reports on application of on-flow two-dimensional (2D) NMR in HPLC-NMR. Here we present an alternative method for recording real-time 2D-NMR spectrum (total correlation spectroscopy, TOCSY) on a commercial HPLC-NMR system. The method is based on well-established Hadamard matrix for 2D-NMR frequency encoding. In addition, a modified/improved solvent suppression approach is incorporated. This makes it possible to carry out the experiment with both polar and gradient eluents, the widely used chromatographic conditions. The method is exampled using a synthesized mixture of three amino acids (His, Phe and Try) and a human urine sample. The method demonstrated here may be utilized for high-throughput structural or unknown component identification and fast dynamic study in a variety of applications. [Copyright &y& Elsevier]

Abstract: A competitive low-affinity binding model was proposed for determining the number of mutual (overlapped) and specific binding sites of two ligands (A, B) on a protein (P). To use the model, one needs to carry out a titration experiment by adding either ligand A or B into a three-component system (A–B–P), and to monitor the spectroscopic parameter changes. Fitting the titration curve to the proposed model, one can get the mutual and specific binding sites of the two ligands on the protein. The model was examined by using human serum albumin (HSA) as a receptor and tolmetin (TOL) and salicylic acid (SAL) as ligands. Proton longitudinal relaxation rates (R 1) were measured on a 500-MHz NMR spectrometer during the titration and used to derive the mutual binding sites. It was found that among the binding sites of 32±4 for SAL and 28±2 for TOL on HSA, there were 17±5 mutual sites for the two ligands. This result indicates that, although HSA has large binding capacities for most ligands, there are still a reasonable amount of the low-affinity binding sites that are structure selective. [Copyright &y& Elsevier]