m6A modification: recent advances, anticancer targeted drug discovery and beyond.

Abnormal N6-methyladenosine (m6A) modification is closely associated with the occurrence, development, progression and prognosis of cancer, and aberrant m6A regulators have been identified as novel anticancer drug targets. Both traditional medicine-related approaches and modern drug discovery platforms have been used in an attempt to develop m6A-targeted drugs. Here, we provide an update of the latest findings on m6A modification and the critical roles of m6A modification in cancer progression, and we summarize rational sources for the discovery of m6A-targeted anticancer agents from traditional medicines and computer-based chemosynthetic compounds. This review highlights the potential agents targeting m6A modification for cancer treatment and proposes the advantage of artificial intelligence (AI) in the discovery of m6A-targeting anticancer drugs. Three stages of m6A-targeting anticancer drug discovery: traditional medicine-based natural products, modern chemical modification or synthesis, and artificial intelligence (AI)-assisted approaches for the future.

RNA N6-methyladenosine modification promotes auxin biosynthesis required for male meiosis in rice.

N6-methyladenosine (m6A) RNA modification confers an essential layer of gene regulation in living organisms, including plants; yet, the underlying mechanisms of its deposition on specific target mRNAs involved in key plant developmental processes are so far unknown. Here, we show that a core component of the rice m6A methyltransferase complex, OsFIP37, is recruited by an RNA-binding protein, OsFIP37-associated protein 1 (OsFAP1), to mediate m6A RNA modification on an auxin biosynthesis gene, OsYUCCA3, during microsporogenesis. This stabilizes OsYUCCA3 mRNA and promotes local auxin biosynthesis in anthers during male meiosis, which is essential for meiotic division and subsequent pollen development in rice. Loss of function of OsFAP1 causes dissociation of OsFIP37 with OsYUCCA3 and the resulting abolished m6A deposition on OsYUCCA3. Our findings reveal that OsFAP1-dependent m6A deposition on OsYUCCA3 by OsFIP37 constitutes a hitherto unknown link between RNA modification and hormonal control of male meiosis in plant reproductive development.

Resveratrol Supplementation Attenuates Cognitive and Molecular Alterations under Maternal High-Fat Diet Intake: Epigenetic Inheritance over Generations.

Environmental factors such as maternal high-fat diet (HFD) intake can increase the risk of age-related cognitive decline in adult offspring. Epigenetic mechanisms are a possible link between diet effect and neurodegeneration across generations. Here, we found a significant decrease in triglyceride levels in a high-fat diet with resveratrol (RSV) HFD + RSV group and the offspring. Firstly, we obtained better cognitive performance in HFD+RSV groups and their offspring. Molecularly, a significant increase in DNA methylation (5-mC) levels, as well as increased gene expression of DNA methyltransferase 1 (Dnmt1) and Dnmt3a in HFD + RSV F1 group, were found. Furthermore, a significant increase of N6-Methyladenosine methylation (m6A) levels in HFD+RSV F1, as well as changes in gene expression of its enzymes Methyltransferase like 3 (Mettl3) and FTO alpha-ketoglutarate dependent dioxygenase (Fto) were found. Moreover, we found a decrease in gene expression levels of pro-inflammatory markers such as Interleukin 1ß (Il1-ß), Interleukin 6 (Il-6), Tumor necrosis factor-α (Tnf-α), C-X-C motif chemokine ligand 10 (Cxcl-10), the pro-inflammatory factors monocyte chemoattractant protein 1 (Mcp-1) and Tumor growth factor-ß1 (Tgf-ß1) in HFD+RSV and HFD+RSV F1 groups. Moreover, there was increased gene expression of neurotrophins such as Neural growth factor (Ngf), Neurotrophin-3 (Nt3), and its receptors Tropomyosin receptor kinase TrkA and TrkB. Likewise, an increase in protein levels of brain-derived neurotrophic factor (BDNF) and phospho-protein kinase B (p-Akt) in HFD+RSV F1 was found. These results suggest that maternal RSV supplementation under HFD intake prevents cognitive decline in senescence-accelerated mice prone 8 (SAMP8) adult offspring, promoting a reduction in triglycerides and leptin plasma levels, changes in the pro-inflammatory profile, and restoring the epigenetic landscape as well as synaptic plasticity.

Electroacupuncture alleviates inflammatory pain via adenosine suppression and its mediated substance P expression.

BACKGROUND: Acupuncture has been widely used for alleviating pain. However, its mechanisms remain largely enigmatic. OBJECTIVE: In the present study, we focused on whether the analgesic effect of electroacupuncture is related to its regulation on adenosine and substance P expression. METHODS: We established chronic inflammatory pain model in rats through a single injection of Complete Freund's Adjuvant, and then we treated animals using daily electroacupuncture. We applied seven bilateral sessions of electroacupuncture (ST36 and BL60, 0.5 to 1.5 mA, initial strength of 0.5 mA, increased by 0.5 mA every 10 minutes, for 30 minutes per session, one section per day) to Complete Freund's Adjuvant rats for seven days. The analgesic effect of electroacupuncture was evaluated by measuring paw withdrawal threshold in rats that received mechanical and thermal stimulation. RESULTS: Daily electroacupuncture stimulation effectively increased paw withdrawal threshold in Complete Freund's Adjuvant rats. Electroacupuncture increased the adenosine level in zusanli. A further study showed that electroacupuncture could decrease substance P, neurokinin-1 receptor, tumor necrosis factor-alpha, interleukin-1ß, interleukin-6 and CD68 levels in dorsal root ganglion. Interestingly, direct injection of adenosine A1 or substance P receptor antagonists, or dorsal nerve root transection could significantly impair electroacupuncture induced analgesic actions in Complete Freund's Adjuvant rats could and reduce the levels of substance P, neurokinin-1 receptor, tumor necrosis factor-alpha, interleukin-1ß, interleukin-6 and CD68. Finally, we confirmed that direct injection of adenosine A1 receptor agonist replicated the analgesic effect of electroacupuncture. CONCLUSION: Our results indicate regulation of adenosine-mediated substance P secretion. Substance P-mediated pathway may be involved in the analgesia process by electroacupuncture in rats.

Electroacupuncture alleviates inflammatory pain via adenosine suppression and its mediated substance P expression / A eletroacupuntura alivia a dor inflamatória por meio da supressão de adenosina e da expressão mediada de substância P

ABSTRACT Background: Acupuncture has been widely used for alleviating pain. However, its mechanisms remain largely enigmatic. Objective: In the present study, we focused on whether the analgesic effect of electroacupuncture is related to its regulation on adenosine and substance P expression. Methods: We established chronic inflammatory pain model in rats through a single injection of Complete Freund's Adjuvant, and then we treated animals using daily electroacupuncture. We applied seven bilateral sessions of electroacupuncture (ST36 and BL60, 0.5 to 1.5 mA, initial strength of 0.5 mA, increased by 0.5 mA every 10 minutes, for 30 minutes per session, one section per day) to Complete Freund's Adjuvant rats for seven days. The analgesic effect of electroacupuncture was evaluated by measuring paw withdrawal threshold in rats that received mechanical and thermal stimulation. Results: Daily electroacupuncture stimulation effectively increased paw withdrawal threshold in Complete Freund's Adjuvant rats. Electroacupuncture increased the adenosine level in zusanli. A further study showed that electroacupuncture could decrease substance P, neurokinin-1 receptor, tumor necrosis factor-alpha, interleukin-1β, interleukin-6 and CD68 levels in dorsal root ganglion. Interestingly, direct injection of adenosine A1 or substance P receptor antagonists, or dorsal nerve root transection could significantly impair electroacupuncture induced analgesic actions in Complete Freund's Adjuvant rats could and reduce the levels of substance P, neurokinin-1 receptor, tumor necrosis factor-alpha, interleukin-1β, interleukin-6 and CD68. Finally, we confirmed that direct injection of adenosine A1 receptor agonist replicated the analgesic effect of electroacupuncture. Conclusion: Our results indicate regulation of adenosine-mediated substance P secretion. Substance P-mediated pathway may be involved in the analgesia process by electroacupuncture in rats.

RESUMO Introdução: A acupuntura tem sido amplamente utilizada para alívio de dor. No entanto, seus mecanismos são muito pouco conhecidos. Objetivo: Investigar a relação entre o efeito analgésico da eletroacupuntura e a regulação da expressão de adenosina e de substância P. Métodos: Utilizou-se um modelo de dor inflamatória crônica em ratos por injeção única do Adjuvante Completo de Freund e, em seguida, os animais foram tratados com eletroacupuntura diariamente. Foram aplicadas sete sessões bilaterais de eletroacupuntura (ST36 e BL60, 0,5 a 1,5 mA, força inicial de 0,5 mA, aumentada em 0,5 mA a cada 10 minutos, 30 minutos por sessão, uma sessão por dia) em ratos com Adjuvante Completo de Freund, por sete dias. O efeito analgésico da eletroacupuntura foi avaliado pela medida do limiar de retirada da pata em ratos que receberam estimulações mecânica e térmica. Resultados: A estimulação diária com eletroacupuntura aumentou efetivamente o limiar de retirada da pata em ratos com Adjuvante Completo de Freund. A eletroacupuntura aumentou o nível de adenosina na região zusanli. Estudos posteriores mostraram que a eletroacupuntura poderia diminuir os níveis de substância P, receptor de neurocinina-1, fator de necrose tumoral-alpha, interleucina-1β, interleucina-6 e CD68 nos gânglios da raiz dorsal. Curiosamente, a injeção direta de antagonistas do receptor de adenosina A1 ou de substância P, ou a transecção da raiz do nervo dorsal, podem prejudicar significativamente as ações analgésicas induzidas pela eletroacupuntura em ratos com Adjuvante Completo de Freund e reduzir os níveis de substância P, receptor de neurocinina-1, fator de necrose tumoral-alfa, interleucina-1β, interleucina-6 e CD68. Por fim, confirmamos que a injeção direta de um agonista do receptor da adenosina A1 reproduziu os efeitos analgésicos da eletroacupuntura. Conclusão: Nossos resultados indicam a regulação da secreção da substância P mediada pela adenosina. A via mediada pela substância P pode estar envolvida no processo de analgesia por eletroacupuntura em ratos.

Selenium bioisosteric replacement of adenosine derivatives promoting adiponectin secretion increases the binding affinity to peroxisome proliferator-activated receptor δ.

N6-(3-Iodobenzyl)adenosine-5'-N-methyluronamide (1a, IB-MECA) exhibited polypharmacological characteristics targeting A3 adenosine receptor (AR), peroxisome proliferator-activated receptor (PPAR) γ, and PPARδ, simultaneously. The bioisosteric replacement of oxygen in 4'-oxoadenosines with selenium significantly increased the PPARδ-binding activity. 2-Chloro-N6-(3-iodobenzyl)-4'-selenoadenosine-5'-N-methyluronamide (3e) and related 4'-selenoadenosine derivatives significantly enhanced adiponectin biosynthesis during adipogenesis in human bone marrow mesenchymal stem cells (hBM-MSCs). The PPARδ-binding affinity, but not the A3 AR binding affinity, of 4'-selenoadenosine derivatives correlated with their adiponectin secretion stimulation. Compared with the sugar ring of 4'-oxoadenosine, that of 4'-selenoadenosine was more favorable in forming the South sugar conformation. In the molecular docking simulation, the South sugar conformation of compound 3e formed additional hydrogen bonds inside the PPARδ ligand-binding pocket compared with the North conformation. Therefore, the sugar conformation of 4'-selenoadenosine PPAR modulators affects the ligand binding affinity against PPARδ.

Dual sensing reporter system of assembled gold nanoparticles toward the sequential colorimetric detection of adenosine and Cr(III).

A facile and sensitive sequential colorimetric detection strategy for adenosine and Cr3+ has been presented by using the aptamer and 11-mercaptoundecanoic acid assembled gold nanoparticles. The thiolated DNA and 11-mercaptoundecanoic acid was simultaneously assembled to the surface of gold nanoparticles in one step by gold-sulfur interaction. Adenosine aptamer was linked to functionalized gold nanaoparticles based on the strict complementary nature of the DNA base pairs. Conformational change of aptamer will be induced due to its specific binding with targets. As a result, this aptamer tethered aggregated nanoparticles underwent fast disassembly into dispersed nanoparticles upon binding of adenosine, and this distance change between particles induced a distinct solution color changing from blue to red. The dispersed particles were sensitive to Cr3+ due to the chelation effect between the carboxyl group of 11-mercaptoundecanoic acid and metal ions, and further occurred obvious aggregation accompanying with a color change from red to blue. Depended on this principle, a sensitive and selective sequential colorimetric sensor for detection of adenosine and Cr3+ was developed. The proposed colorimetric sensor exhibited wide linear ranges and low detection limits towards the detection of adenosine and Cr3+. Regarding adenosine, linear range was 1 × 10-7 ∼ 1 × 10-4 M with low detection limit of 1.8 × 10-8 M, and the naked eye detection limit was estimated as 20 µM. With regard to Cr3+, good linear relationship was ranged from 1 × 10-10 to 1 × 10-6 M with low detection limit of 1.7 × 10-11 M，and the naked eye detection limit was as low as 0.1 nM. Meanwhile, bifunctional recognition was successfully used for practical human urine samples with good recoveries from 89.0% to 112.6% for adenosine and 90.2%-113.4% for Cr3+. It also highlights the potential applications of other aptamers and ligands in cascade analysis of other analytes.

Nucleoside analogs in the study of the epitranscriptome.

Over 150 unique RNA modifications are now known including several nonstandard nucleotides present in the body of messenger RNAs. These modifications can alter a transcript's function and are collectively referred to as the epitrancriptome. Chemically modified nucleoside analogs are poised to play an important role in the study of these epitranscriptomic marks. Introduced chemical features on nucleic acid strands provide unique structures or reactivity that can be used for downstream detection or quantification. Three methods are used in the field to synthesize RNA containing chemically modified nucleoside analogs. Nucleoside analogs can be introduced by metabolic labeling, via polymerases with modified nucleotide triphosphates or via phosphoramidite-based chemical synthesis. In this review, these methods for incorporation of nucleoside analogs will be discussed with specific recently published examples pertaining to the study of the epitranscriptome.

Dynamic stacking of an expected branch point adenosine in duplexes containing pseudouridine-modified or unmodified U2 snRNA sites.

The pre-mRNA branch point sequence (BPS) anneals with a pseudouridine-modified region of the U2 small nuclear (sn)RNA, and offers a 2' hydroxyl group of a bulged adenosine as the nucleophile for the first catalytic step of pre-mRNA splicing. To increase our structural understanding of branch site selection, we characterized a duplex containing a BPS sequence that is common among multicellular eukaryotes (5'-UACUGAC-3') and the complementary U2 snRNA site using NMR. A major conformation of the expected branch site adenosine stacked within the duplex and paired with the conserved pseudouridine of the U2 snRNA strand. In contrast, the guanosine preceding the branch site appeared flexible and had weak contacts with the surrounding nucleotides. Pseudouridine-modified and unmodified U2 snRNA-BPS-containing duplexes remained structurally similar. These results highlight the importance of auxiliary factors to achieve the active bulged conformation of the branch site nucleophile for the first step of pre-mRNA splicing.

Effects of Various Treatments on Extraction of the Main Bioactive Components and Determination of Biological Activity of Extracts from the Caterpillar Medicinal Mushroom Cordyceps militaris (Ascomycetes).

In this study we optimized the extraction of cordycepin from Cordyceps militaris through the use of an orthogonal test based on single-factor experiments. The results showed that the largest amount of cordycepin (1260.28 ± 46.38 µ.g/g) was achieved with an extraction time of 15 minutes, an extraction temperature of 100°C, and a liquid-to-material ratio of 50 mL/g. The antioxidant activities and xanthine oxidase inhibitory activity of aqueous extracts, ethanol extracts, and polysaccharides from C. militaris were subsequently determined. The results showed that the various extracts and polysaccharides all had certain antioxidant activities. However, the polysaccharides had a strong ability to scavenge superoxide radicals and at 0.5-3.0 mg/mL had almost the same effect as vitamin C. In addition, the polysaccharides displayed concentration-dependent xanthine oxidase inhibitory activity, but the ethanol extract exhibited a negative relation at concentrations of 0.5-3.0 mg/mL, whereas the aqueous extracts had very low (< 10%) xanthine oxidase inhibitory activity. Our results indicate that C. militaris has potential use as part of well-balanced diets and in the pharmaceutical industry.

Spectrum of activity testing for therapeutics against all four dengue virus serotypes in AG129 mouse models: Proof-of-concept studies with the adenosine nucleoside inhibitor NITD-008.

Dengue is a mosquito-borne disease of global public health importance caused by four genetically and serologically related viruses (DENV-1 to DENV-4). Efforts to develop effective vaccines and therapeutics for dengue have been slowed by the paucity of preclinical models that mimic human disease. DENV-2 models in interferon receptor deficient AG129 mice were an important advance but only allowed testing against a single DENV serotype. We have developed complementary AG129 mouse models of severe disseminated dengue infection using strains of the other three DENV serotypes. Here we used the adenosine nucleoside inhibitor NITD-008 to show that these models provide the ability to perform comparative preclinical efficacy testing of candidate antivirals in vivo against the full-spectrum of DENV serotypes. Although NITD-008 was effective in modulating disease caused by all DENV serotypes, the variability in protection among DENV serotypes was greater than expected from differences in activity in in vitro testing studies emphasizing the need to undertake spectrum of activity testing to help in prioritization of candidate compounds for further development.

Nanolayered hybrid mediates synergistic co-delivery of ligand and ligation activator for inducing stem cell differentiation and tissue healing.

Cellular behaviors, such as differentiation, are regulated by complex ligation processes involving cell surface receptors, which can be activated by various divalent metal cations. The design of nanoparticle for co-delivery of ligand and ligation activator can offer a novel strategy to synergistically stimulate ligation processes in vivo. Here, we present a novel layered double hydroxide (LDH)-based nanohybrid (MgFe-Ado-LDH), composed of layered MgFe hydroxide nanocarriers sandwiching the adenosine cargo molecule, maintained through an electrostatic balance, to co-deliver the adenosine (Ado) ligand from the interlayer spacing and the Mg2+ ion (ligation activator) through the dissolution of the MgFe nanocarrier itself. Our findings demonstrate that the MgFe-Ado-LDH nanohybrid promoted osteogenic differentiation of stem cells through the synergistic activation of adenosine A2b receptor (A2bR) by the dual delivery of adenosine and Mg2+ ions, outperforming direct supplementation of adenosine alone. Furthermore, the injection of the MgFe-Ado-LDH nanohybrid and stem cells embedded within hydrogels promoted the healing of rat tibial bone defects through the rapid formation of fully integrated neo-bone tissue through the activation of A2bR. The newly formed bone tissue displayed the key features of native bone, including calcification, mature tissue morphology, and vascularization. This study demonstrates a novel and effective strategy of bifunctional nanocarrier-mediated delivery of ligand (cargo molecule) and activation of its ligation to receptor by the nanocarrier itself for synergistically inducing stem cell differentiation and tissue healing in vivo, thus offering novel design of biomaterials for regenerative medicine.

Synthesis and antibacterial activity of 5'-tetrachlorophthalimido and 5'-azido 5'-deoxyribonucleosides.

Reported is an efficient synthesis of adenyl and uridyl 5'-tetrachlorophthalimido-5'-deoxyribonucleosides, and guanylyl 5'-azido-5'-deoxyribonucleosides, which are useful in solid-phase synthesis of phosphoramidate and ribonucleic guanidine oligonucleotides. Replacement of 5'-hydroxyl with tetrachlorophthalimido group was performed via Mitsunobu reaction for adenosine and uridine. An alternative method was applied for guanosine which replaced the 5'-hydroxyl with an azido group. The resulting compounds were converted to 5'-amino-5'-deoxyribonucleosides for oligonucleotide synthesis. Synthetic intermediates were tested as antimicrobials against six bacterial strains. All analogs containing the 2',3'-O-isopropylidine protecting group demonstrated antibacterial activity against Neisseria meningitidis, and among those analogs with 5'-tetrachlorophthalimido and 5'-azido demonstrated increased antibacterial effect.

Acidified Hot Water Extraction of Adenosine, Cordycepin, and Polysaccharides from the Chinese Caterpillar Mushroom, Ophiocordyceps sinensis CS1197 (Ascomycetes): Application of an Artificial Neural Network and Evaluation of Antioxidant and Antibacterial Activities.

The effects of process variables (temperature, time, and pH) on the extraction of adenosine, cordycepin, and polysaccharides from Ophiocordyceps sinensis CS1197 were studied using response surface methodology (RSM) and an artificial neural network (ANN). The ANN model resulted in low root mean square errors (0.022, 0.079, 0.018) and high R2 values (0.995, 0.934, 0.997) for adenosine, cordycepin, and polysaccharide yields, respectively, which implied good agreement between the predicted and actual data. An overall desirability of 0.86 suggested optimal extraction conditions (temperature, 70°C; time, 1 hour; and pH ~4) for adenosine (0.205%) and cordycepin (0.246%) yields. For polysaccharide yield (6.34%), an overall desirability of 0.93 suggested extraction conditions: temperature, 87°C; time, 3.4 hours, and pH ~4. The water extract exhibited better antioxidant activity. The antibacterial activity of the water extract was assayed against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli, and larger amounts of the extract (30 and 50 mg) exhibited antibacterial activity (<35%). The predictive ability of an ANN is superior to RSM and resulted in the best agreement between experimental and predicted values.

Exploring the purine core of 3'-C-ethynyladenosine (EAdo) in search of novel nucleoside therapeutics.

A series of new nucleoside analogues based on a C-3 branched ethynyl sugar derivative as present in 3'-C-ethynylcytidine (ECyd) and -adenosine (EAdo), combined with modified purine bases was synthetized and evaluated against a broad array of viruses and tumour cell lines. The pronounced cytostatic activity of EAdo was confirmed. EAdo and its 2,6-diaminopurine analogue showed inhibitory activity against vaccinia virus (EC50: 0.31 and 51 µM, respectively). Derivative 10 on the other hand was found active against varicella zoster virus (EC50: 4.68 µM).

Discovery and structural analyses of S-adenosyl-L-homocysteine hydrolase inhibitors based on non-adenosine analogs.

Optimization of a new series of S-adenosyl-L-homocysteine hydrolase (AdoHcyase) inhibitors based on non-adenosine analogs led to very potent compounds 14n, 18a, and 18b with IC50 values of 13 ± 3, 5.0 ± 2.0, and 8.5 ± 3.1 nM, respectively. An X-ray crystal structure of AdoHcyase with NAD(+) and 18a showed a novel open form co-crystal structure. 18a in the co-crystals formed intramolecular eight membered ring hydrogen bond formations. A single crystal X-ray structure of 14n also showed an intramolecular eight-membered ring hydrogen bond interaction.

Discovery of ß-D-2'-deoxy-2'-α-fluoro-4'-α-cyano-5-aza-7,9-dideaza adenosine as a potent nucleoside inhibitor of respiratory syncytial virus with excellent selectivity over mitochondrial RNA and DNA polymerases.

Novel 4'-substituted ß-d-2'-deoxy-2'-α-fluoro (2'd2'F) nucleoside inhibitors of respiratory syncytial virus (RSV) are reported. The introduction of 4'-substitution onto 2'd2'F nucleoside analogs resulted in compounds demonstrating potent cell based RSV inhibition, improved inhibition of the RSV polymerase by the nucleoside triphosphate metabolites, and enhanced selectivity over incorporation by mitochondrial RNA and DNA polymerases. Selectivity over the mitochondrial polymerases was found to be extremely sensitive to the specific 4'-substitution and not readily predictable. Combining the most potent and selective 4'-groups from N-nucleoside analogs onto a 2'd2'F C-nucleoside analog resulted in the identification of ß-D-2'-deoxy-2'-α-fluoro-4'-α-cyano-5-aza-7,9-dideaza adenosine as a promising nucleoside lead for RSV.

Ambient mass spectrometry imaging metabolomics method provides novel insights into the action mechanism of drug candidates.

Elucidation of the mechanism of action for drug candidates is fundamental to drug development, and it is strongly facilitated by metabolomics. Herein, we developed an imaging metabolomics method based on air-flow-assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI) under ambient conditions. This method was subsequently applied to simultaneously profile a novel anti-insomnia drug candidate, N(6)-(4-hydroxybenzyl)-adenosine (NHBA), and various endogenous metabolites in rat whole-body tissue sections after the administration of NHBA. The principal component analysis (PCA) represented by an intuitive color-coding scheme based on hyperspectral imaging revealed in situ molecular profiling alterations in response to stimulation of NHBA, which are in a very low intensity and hidden in massive interferential peaks. We found that the abundance of six endogenous metabolites changed after drug administration. The spatiotemporal distribution indicated that five altered molecules­including neurotransmitter γ-aminobutyric acid, neurotransmitter precursors choline and glycerophosphocholine, energy metabolism-related molecules adenosine (an endogenous sleep factor), and creatine­are closely associated with insomnia or other neurological disorders. These findings not only provide insights into a deep understanding on the mechanism of action of NHBA, but also demonstrate that the AFADESI-MSI-based imaging metabolomics is a powerful technique to investigate the molecular mechanism of drug action, especially for drug candidates with multitarget or undefined target in the preclinical study stage.

Cordycepin and N6-(2-hydroxyethyl)-adenosine from Cordyceps pruinosa and their interaction with human serum albumin.

Cordyceps pruinosa (CP) is often used as Traditional Chinese Medicine, but the substance basis of its medicinal properties is unclear. In this study, two compounds were isolated from CP cultures by column chromatography, and identified as cordycepin and N6-(2-hydroxyethyl)-adenosine (HEA) by Nuclear Magnetic Resonance. In order to understand the efficacy of these two substances as potential therapeutic agents, it is necessary to explore their binding with proteins. The molecular mechanisms of interaction between cordycepin, HEA and human serum albumin (HSA) were studied using UV and fluorescence spectroscopy. The bingding constants between HSA and cordycepin were 4.227, 3.573 and 3.076 × 10(3)·at 17, 27 and 37°C respectively, and that of HSA and HEA were 27.102, 19.409 and 13.002 × 10(3)·at the three tempretures respectively. Both cordycepin and HEA can quench the intrinsic fluorescence of HSA via static quenching, and they can bind with HSA to form complexes with a single binding site. The interaction forces between cordycepin and HSA were determined as electrostatic and hydrophobic, and those of HEA and HSA were hydrogen bonding and van der Waals forces. Using Foster's equation, the distance between fluorophores of cordycepin and HSA, and HEA and HSA are estimated to be 5.31 nm and 4.98 nm, respectively. In this study, cordycepin was isolated for the first time from CP, and will provide a new source of cordycepin and expand the use of this taxon. The interaction mechanisms between cordycepin and HSA was studied for the first time, which will provide a useful guide for the clinical application of cordycepin. The pharmacological importance of this study is to understand the interaction of HSA with cordycepin and HEA, which will be essential for the future designing of drugs based on the two compounds.

On the formation of dendrimer/nucleolipids surface films for directed self-assembly.

We describe the formation and structure of nucleolipid/dendrimer multilayer films controlled by non-covalent interactions to obtain biomaterials that exhibit molecular recognition of nucleic acids. Layers of cationic poly(amidoamine) (PAMAM) dendrimers of generation 4 and the anionic nucleolipids 1,2-dilauroyl-sn-glycero-3-phosphatidylnucleosides (DLPNs) based on uridine (DLPU) and adenosine (DLPA) were first formed at the silica-water interface. The PAMAM/DLPN layers were then exposed to short oligonucleotides, polynucleotides and single stranded DNA (ssDNA). The interfacial properties were characterized using quartz crystal microbalance with dissipation monitoring, attenuated total reflection Fourier transform infrared spectroscopy and neutron reflectometry. Both types of DLPN were found to adsorb as aggregates to preadsorbed PAMAM monolayers with a similar interfacial structure and composition before rinsing with pure aqueous solution. Nucleic acids were found to interact with PAMAM/DLPA layers due to base pairing interactions, while the PAMAM/DLPU layers did not have the same capability. This was attributed to the structure of the DLPA layer, which is formed by aggregates that extend from the interface towards the bulk after rinsing with pure solvent, while the DLPU layer forms compact structures. In complementary experiments using a different protocol, premixed PAMAM/DLPN samples adsorbed to hydrophilic silica only when the mixtures contained positively charged aggregates, which is rationalized in terms of electrostatic forces. The PAMAM/DLPA layers formed from the adsorption of these mixtures also bind ssDNA although in this case the adsorption is mediated by the opposite charges of the film and the nucleic acid rather than specific base pairing. The observed molecular recognition of nucleic acids by dendrimers functionalized via non-covalent interactions with nucleolipids is discussed in terms of biomedical applications such as gene vectors and biosensors.