Phytochemistry and Pharmacology of Sesquiterpenoids from Atractylodes DC. Genus Rhizomes.

The rhizomes of the genus Atractylodes DC. consist of various bioactive components, including sesquiterpenes, which have attracted a great deal of research interest in recent years. In the present study, we reviewed the previously published literatures prior to November 2023 on the chemical structures, biosynthetic pathways, and pharmacological activities of the sesquiterpenoids from this genus via online databases such as Web of Science, Google Scholar, and ScienceDirect. Phytochemical studies have led to the identification of more than 160 sesquiterpenes, notably eudesmane-type sesquiterpenes. Many pharmacological activities have been demonstrated, particularly anticancer, anti-inflammatory, and antibacterial and antiviral activities. This review presents updated, comprehensive and categorized information on the phytochemistry and pharmacology of sesquiterpenes in Atractylodes DC., with the aim of offering guidance for the future exploitation and utilization of active ingredients in this genus.

Dynamic changes of ginsenosides in Panax quinquefolium fruit at different development stages measured using UHPLC-Orbitrap MS.

RATIONALE: Some studies have shown that Panax quinquefolium fruit (PQF) could also be used as a potential medicinal resource. However, little is known about the composition of ginsenosides and their dynamic changes at different development stages of PQF. Therefore, this study is of great significance for the metabolomics and rational utilization of PQF. METHODS: The samples were analyzed using ultra-high-performance liquid chromatography combined with an Orbitrap mass spectrometer (UHPLC-Orbitrap MS), and the method of metabonomics was applied to profile the dynamic changes of ginsenosides in PQF at different development stages. RESULTS: A total of 109 ginsenosides were identified or tentatively characterized. Samples collected from different development stages were significantly discriminated according to ginsenoside contents. A total of 25 potential chemical markers enabling the differentiation were discovered. CONCLUSIONS: For the first time, the study developed an UHPLC-Orbitrap MS-based approach to detect ginsenoside in PQF at different development stages using a non-targeted mode. This comprehensive phytochemical profile study revealed the structural diversity and discrimination of ginsenosides in PQF at different development stages, which could provide the basis for the metabolomics and rational application of PQF.

Knockdown of RAD18 inhibits glioblastoma development.

This study aimed at investigating the role of RAD18 in the regulation of glioblastoma development as well as the underlying mechanisms. The human glioblastoma U251 and U87MG cells were transfected with siRNAs specifically targeting RAD18, and the effects of knockdown of RAD18 on the viability, apoptosis, migration, and invasion of U251 and U87MG cells were investigated. Transcriptome sequencing of the siRNA-RAD18-tranfected and siRNA-NC-transfected U251 cells was performed, followed by bioinformatic analyses for sequencing data. The results showed that knockdown of RAD18 significantly inhibited cell viability, promoted apoptosis, and suppressed migration and invasion of U251 and U87MG cells. Bioinformatic analyses of sequencing data identified 1,051 differentially expressed genes (DEGs) (369 up- and 682 downregulated genes) in the siRNA-RAD18-transfected U251 cells compared with siRNA-NC-transfected U251 cells. Eleven DEGs, including nerve growth factor (NGF), colony-stimulating factor 2 (CSF2), matrix metallopeptidase 1 (MMP1), platelet-derived growth factor receptor α (PDGFRA), and heme oxygenase 1 (HMOX1), were identified as the hub nodes in protein-protein interaction (PPI) network. Moreover, the aforementioned 11 hub genes were significantly enriched in PI3K-Akt signaling pathway and GO functions associated with the extracellular region. Notably, quantitative real-time polymerase chain reaction further confirmed that the expression levels of NGF, CSF2, HMOX1, and MMP1 were significantly downregulated, while that of PDGFRA was markedly upregulated in the siRNA-RAD18-transfected U251 cells than in the siRNA-NC cells. In conclusion, the knockdown of RAD18 may inhibit glioblastoma development by regulating the expression of the aforementioned key DEGs.

A dual-channel ratiometric fluorescent probe for determination of the activity of tyrosinase using nitrogen-doped graphene quantum dots and dopamine-modified CdTe quantum dots.

A dual-channel ratiometric fluorometric assay is described for the determination of the activity of the enzyme tyrosinase (TYR). It is making use of blue-emitting nitrogen-doped graphene quantum dots (bQDs) and of red-emitting dopamine-modified CdTe quantum dots (DA-rQDs). A mixture of the two kinds of quantum dots was prepared, with the ratiometric fluorescence intensity of red to blue adjusted to 5:1. The dopamine on the rQDs is catalytically oxidized by TYR to form dopamine quinone, and this leads to a reduction of the intensity of red fluorescence (peaking at 644 nm). The emission of the bQDs (peaking at 440 nm) represents a stable reference signal. After adding different activities of TYR, the color of the fluorescence of the system continuously changes from red to blue. This can also be visually observed. The ratio of luminescence intensities (at 644/440 nm) can be used to quantify the activity of TYR, and the detection limit is 4.5 mU mL-1. In addition, a test strip is described based on the above method. Graphical abstract Schematic representation of the ratiometric fluorometric method for determination of the activity of tyrosinase (TYR). (The full name of the abbreviation in the Scheme: 1-ethyl-3-[3-(dimethylamino)-propyl] carbodiimide hydrochloride (EDC), dopamine (DA), N-hydroxysuccinimide (NHS), nitrogen-doped graphene quantum dots (bQDs), CdTe quantum dots (rQDs)).

Wnt/ß-catenin signalling pathway mediated aberrant hippocampal neurogenesis in kainic acid-induced epilepsy.

Temporal lobe epilepsy is a chronic disorder of nerve system, mainly characterized by hippocampal sclerosis with massive neuronal loss and severe gliosis. Aberrant neurogenesis has been shown in the epileptogenesis process of temporal lobe epilepsy. However, the molecular mechanisms underlying aberrant neurogenesis remain unclear. The roles of Wnt signalling cascade have been well established in neurogenesis during multiple aspects. Here, we used kainic acid-induced rat epilepsy model to investigate whether Wnt/ß-catenin signalling pathway is involved in the aberrant neurogenesis in temporal lobe epilepsy. Immunostaining and western blotting results showed that the expression levels of ß-catenin, Wnt3a, and cyclin D1, the key regulators in Wnt signalling pathway, were up-regulated during acute epilepsy induced by the injection of kainic acids, indicating that Wnt signalling pathway was activated in kainic acid-induced temporal lobe epilepsy. Moreover, BrdU labelling results showed that blockade of the Wnt signalling by knocking down ß-catenin attenuated aberrant neurogenesis induced by kainic acids injection. Altogether, Wnt/ß-catenin signalling pathway mediated hippocampal neurogenesis during epilepsy, which might provide new strategies for clinical treatment of temporal lobe epilepsy. Temporal lobe epilepsy is a chronic disorder of nerve system, mainly characterized by hippocampal sclerosis. Aberrant neurogenesis has been shown to involve in the epileptogenesis process of temporal lobe epilepsy. In the present study, we discovered that Wnt3a/ß-catenin signalling pathway serves as a link between aberrant neurogenesis and underlying remodelling in the hippocampus, leading to temporal lobe epilepsy, which might provide new strategies for clinical treatment of temporal lobe epilepsy.

Tetramethylpyrazine alleviated cytokine synthesis and dopamine deficit and improved motor dysfunction in the mice model of Parkinson's disease.

It was previously reported that cytokines and neurotoxins released from activated inflammatory cells induced the loss of projecting dopaminergic neurons in the substantia nigra, which triggered the pathogenesis of PD. The present study investigated the effect of treatment with tetramethylpyrazine (TMP) on the central cytokine synthesis, striatal dopamine content and glutamatergic transmission, and behavioral performance in the rotarod task in mice injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Treatment with TMP significantly improved the behavioral performance in the rotarod task in mice injected with MPTP. It also decreased the upregulation of cytokines (tumor necrosis factor-α and interleukin-1ß) in the substantia nigra and striatum in these modeled mice. Furthermore, treatment with TMP significantly improved the dopamine deficits and attenuated the upregulation of striatal basal glutamatergic strength in the striatum of mice injected with MPTP. These results indicated that TMP might serve as a novel approach for the treatment of patients with PD.

Transcriptomic and Metabolomic Research on the Germination Process of Panax ginseng Overwintering Buds.

Ginseng (Panax ginseng C. A. Meyer) is a perennial plant with a long dormancy period. While some researchers employ gibberellin and other substances to stimulate premature germination, this method is limited to laboratory settings and cannot be applied to the field cultivation of ginseng. The mechanism underlying the germination of ginseng overwintering buds remains largely unexplored. Understanding the internal changes during the dormancy release process in the overwintering buds would facilitate the discovery of potential genes, metabolites, or regulatory pathways associated with it. In this study, we approximately determined the onset of dormancy release through morphological observations and investigated the process of dormancy release in ginseng overwintering buds using transcriptomic and metabolomic approaches. Our analyses revealed that the germination process of ginseng overwintering buds is regulated by multiple plant hormones, each acting at different times. Among these, abscisic acid (ABA) and gibberellic acid (GA) serve as classical signaling molecules regulating the dormancy process, while other hormones may promote the subsequent growth of overwintering buds. Additionally, metabolic pathways associated with arginine may be involved in the dormancy release process. Polyamines synthesized downstream may promote the growth of overwintering buds after dormancy release and participate in subsequent reproductive growth. This study provides insights into the germination process of ginseng overwintering buds at the molecular level and serves as a reference for further exploration of the detailed mechanism underlying ginseng overwintering germination in the future.

Beneficial effects of American ginseng (Panax quinquefolius L.) extract residue as a feed additive on production, health status, and gastrointestinal bacteria in sika deer (Cervus nippon).

American ginseng residue is an industrial by-product of ginseng saponin extraction, including polysaccharides and amino acids; however, it is often discarded into the natural environment, representing a waste of resources as well as an environmental issue. In this study, we examined the effects of adding American ginseng residue to the basal diet of sika deer. Twelve antler-bearing male sika deer were assigned randomly to groups fed a diet supplemented with 0% (CON), 1% (LGR), and 3% (HGR) American ginseng residue, respectively, (n = 4 per group) for 5 weeks. Supplementation with 3% American ginseng residue significantly increased antler production and feed utilization efficiency in antler-bearing sika deer (p < 0.05). There were no significant differences in serum biochemical indexes among the three groups, but serum immunoglobulin A and glutathione peroxidase levels were significantly increased in the LGR and HGR groups (p < 0.05). Supplementation with American ginseng residue affected rumen fermentation in sika deer, significantly increasing the rumen contents of acetic acid, propionic acid, and total volatile fatty acids, and decreasing rumen fluid pH (p < 0.05), but had no significant effect on microbial protein or ammoniacal nitrogen content. American ginseng residue also affected the rumen bacterial composition, with significant up-regulation of Bacteroidota abundance in the HGR group, significant increases in Fibrobacterota and Fibrobacter abundance in the LGR group, and a significant decrease in Oscillospiraceae_UCG-005. Supplementation with ginseng residue had no significant effect on volatile fatty acids in the feces of sika deer, but did affect the composition of fecal bacteria, with significant decreases in Desulfobacterota and Rikenellaceae_RC9_gut_group in the HGR group, and a significant increase in Ruminococcus in the LGR group (p < 0.05). In addition, the abundance of Paeniclostridium in the feces decreased linearly with increasing concentration of ginseng residue, with a significant difference among the groups (p < 0.05). This study comprehensively evaluated the effects of American ginseng residue as a potential feed additive on the production performance and gastrointestinal bacterial community in antler-bearing sika deer. The results indicated that ginseng residue was a suitable feed additive for improving production performance and health in sika deer.

A new ocotillol-type ginsenoside from American ginseng berry.

A new ocotillol-type ginsenoside, named pseudoginsenoside F12 (1), was isolated from American ginseng berry, whose structure was elucidated as 6-O-[α-L-2,3-epoxy-rhamnopyranosyl-(1-2)-ß-D-glucopyranosyl]-dammar-20S,24R-epoxy-3ß, 6α,12ß,25-tetraol. In addition, the known alkaloids ß-carboline-1-carboxylic acid (2) and anoectochine (3) were isolated for the first time from the Araliaceae family. The new compound 1 was evaluated for cytotoxicity against MDA-MB-231 breast cancer cell line.

PCSK-9 inhibitors: a new direction for the future treatment of ischemic stroke.

Ischemic stroke, the most prevalent and serious manifestation of cerebrovascular disease, is the main cause of neurological problems that require hospitalization, resulting in disability and death worldwide. Currently, clinical practice focuses on the effective management of blood lipids as a crucial approach to preventing and treating ischemic stroke. In recent years, a great breakthrough in ischemic stroke treatment has been witnessed with the emergence and use of a novel lipid-lowering medication, Proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitor. And its remarkable potential for reducing the occurrence of ischemic stroke is being acknowledged. This article aims to provide a comprehensive review, encompassing the association between PCSK9 and the heightened risk of ischemic stroke, the mechanisms, and the extensive evidence supporting the proven efficacy of PCSK9 inhibitors in clinical practice. Through this present study, we can gain deeper insights into the utilization and impact of PCSK9 inhibitors in treating ischemic stroke.

Association of ALOX5AP gene single nucleotide polymorphisms and cerebral infarction in the Han population of northern China.

BACKGROUND: To explore the association of ALOX5AP single nucleotide polymorphisms (SNPs) and haplotype with the occurrence of cerebral infarction in the Han population of northern China. METHODS: Blood samples were collected from 236 patients of Han ancestry with a history of cerebral infarction and 219 healthy subjects of Han ancestry with no history of cerebral infarction or cardiovascular disease. Applied Biosystems(®) TaqMan(®) SNP Genotyping Assays for SNP genotyping were used to determine the genotypes of 7 ALOX5AP SNP alleles (rs4073259, rs4769874, rs9315050, rs9551963, rs10507391, rs9579646, and rs4147064). RESULTS: One SNP allele (A) of rs4073259 was significantly associated with development of cerebral infarction (P = 0.049). In comparison to control groups, haplotype rs9315050&rs9551963 AAAC [OR (95% CI) = 1.53 (1.02-2.29)], and genotypes rs4147064 CT [OR (95% CI) = 1.872 (1.082-3.241)], and rs9551963 AC [OR (95% CI) = 2.015 (1.165-3.484)] increased the risk of cerebral infarction in patients with hypertension. Genotype rs9579646 GG [OR (95% CI) = 2.926 (1.18-7.251)] increased the risk of, while rs4073259 GG [OR (95% CI) = 0.381 (0.157-0.922)] decreased the risk of cerebral infarction in patients with diabetes. CONCLUSION: These results suggest the ALOX5AP SNP A allele in rs4073259 and genotype rs9579646 GG, rs9551963 AC, and haplotype rs9315050 & rs9551963 AAAC were associated with an increased risk of ischemic stroke in the Han population, while rs4073259 GG was associated with a decreased risk.

Isolation, identification, and quantification of triterpene saponins in the fresh fruits of Panax notoginseng.

This study is to develop a method for isolation, identification, and quantitative determination of dammarane-type triterpene saponins in the Panax notoginseng fruits (PNF). The saponins were isolated by a serious of chromatographic methods, and their structures were elucidated on the basis of spectroscopic evidence and comparison with those of literature reports. Quantitative assay was performed on an ultra-performance liquid chromatography-UV (UPLC-UV) method. As a result, 22 saponins were isolated from the extract of PNF, among them, compound 1 was a new saponin, named as malonylgypenoside IX, compounds 3-10, and 14-18 were isolated from the PNF for the first time. As to quantitative analysis, the calibration curves showed good linearity (r > 0.998) within the concentration range, and the method validation provided good reproducibility and sensitivity for the quantification of eight major saponins with precision and accuracy of less than 3.0%.

Determination of butyrylcholinesterase activity based on thiamine luminescence modulated by MnO2 nanosheets.

In this paper, a novel strategy for biosensing butyrylcholinesterase (BChE) activity is developed based on manganese dioxide (MnO2) nanosheets to modulate the photoluminescence of thiamine (TH). The oxidase-like activity of MnO2 nanosheets enables them to catalyze the oxidation of non-fluorescent substrate TH to generate strong fluorescent thiochrome (TC). When the target BChE is introduced to form thiocholine in the presence of S-butyrylthiocholine iodide (BTCh), MnO2 nanosheets are reduced by thiocholine to Mn2+, resulting in the loss of their oxidase-like activity and the reduction of TC fluorescence. Based on this, a BChE activity fluorescence biosensor is constructed utilizing the luminescence behavior variation of TH and the oxidase-like activity of MnO2 nanosheets. The fluorescence biosensor shows a sensitive response to BChE, and the detection limit reaches 0.036 U L-1. In addition, the feasibility of the biosensor in real samples analysis is studied with satisfactory results.

Mitochondrial BKCa Mediates the Protective Effect of Low-Dose Ethanol Preconditioning on Oxygen-Glucose Deprivation and Reperfusion-Induced Neuronal Apoptosis.

Ischemia-reperfusion (I/R) injury contributes to the morbidity and mortality of ischemic strokes. As an in vitro model, oxygen-glucose deprivation and reperfusion (OGD/R) exposure induces neuronal injury. Low-dose ethanol preconditioning (EtOH-PC) was reported to alleviate neuronal apoptosis during OGD/R. However, whether the mitochondrial BKCa (mitoBKCa) channel is involved in the neuroprotective effect of EtOH-PC during OGD/R is not clearly defined. This study attempts to explore the mediation of the mitoBKCa channel in the neuroprotective effect of EtOH-PC on OGD/R-induced neuronal apoptosis and the underlying mechanisms. OGD/R model was established using primary cortical neurons that were preincubated with ethanol. Subsequently, the cell viability was measured by CCK-8 assay, and the apoptotic cells were determined by TUNEL assay. Annexin V/7-AAD staining and mitochondrial membrane potential using JC-10 were detected by flow cytometry. Western blot analysis was performed to check the apoptosis-related proteins. In the mixed primary culture, 95% neurofilament-positive cells were cortical neurons. Low-dose EtOH-PC (10 mmol/L) for 24 h significantly attenuated the OGD2h/R24h-induced neuronal apoptosis through activating the BKCa channel. Further investigations suggested that ethanol pretreatment increased the mitochondrial membrane potential (MMP) and downregulated the production of cleaved caspase 3 in OGD/R-injured neurons by activating the mitoBKCa channel. Low-dose ethanol pretreatment significantly attenuated the OGD/R-induced neuronal apoptosis mediated by the mitoBKCa channel which modulated the mitochondrial function by impeding the uncontrolled opening of mitochondrial permeability transition pore (MPTP).

New malonylginsenosides from the fresh fruits of Panax notoginseng.

Four new malonylginsenosides, malonylnotoginsenoside Fe (1), malonylnotoginsenoside Ra1 (2), malonylgypenoside LXXV (3), and malonylginsenoside Mc (4), together with two known analogues, malonylfloralginsenoside Rc1 (5) and malonylginsenoside Rc (6), were isolated from the fresh fruits of Panax notoginseng. Their structures were determined by MS and NMR experiments. The anti-proliferative activities of the malonylginsenosides (1-6) against SH-SY5Y human neuroblastoma cell line were evaluated using the MTT assay.

CIRBP Ameliorates Neuronal Amyloid Toxicity via Antioxidative and Antiapoptotic Pathways in Primary Cortical Neurons.

It is generally accepted that the amyloid ß (Aß) peptide toxicity contributes to neuronal loss and is involved in the initiation and progression of Alzheimer's disease (AD). Cold-inducible RNA-binding protein (CIRBP) is reported to be a general stress-response protein, which is induced by different stress conditions. Previous reports have shown the neuroprotective effects of CIRBP through the suppression of apoptosis via the Akt and ERK pathways. The objective of this study is to examine the effect of CIRBP against Aß-induced toxicity in cultured rat primary cortical neurons and attempt to uncover its underlying mechanism. Here, MTT, LDH release, and TUNEL assays showed that CIRBP overexpression protected against both intracellular amyloid ß- (iAß-) induced and Aß 25-35-induced cytotoxicity in rat primary cortical neurons. Electrophysiological changes responsible for iAß-induced neuronal toxicity, including an increase in neuronal resting membrane potentials and a decrease in K+ currents, were reversed by CIRBP overexpression. Western blot results further showed that Aß 25-35 treatment significantly increased the level of proapoptotic protein Bax, cleaved caspase-3, and cleaved caspase-9 and decreased the level of antiapoptotic factor Bcl-2, but were rescued by CIRBP overexpression. Furthermore, CIRBP overexpression prevented the elevation of ROS induced by Aß 25-35 treatment by decreasing the activities of oxidative biomarker and increasing the activities of key enzymes in antioxidant system. Taken together, our findings suggested that CIRBP exerted protective effects against neuronal amyloid toxicity via antioxidative and antiapoptotic pathways, which may provide a promising candidate for amyloid-based AD prevention or therapy.

Changes of 5-hydroxymethyl-2-furfural in fresh and processed ginsengs.

The study estimated changes of 5-hydroxymethyl-2-furfuraldehyde (5-HMF) in different ginseng products with different temperatures and time pretreatment. Heat treatment was performed at various temperatures for 1.50, 2.00, 2.50, and 3.00 hr, respectively. Ultrasonic extraction and reflux extraction were used to evaluate the extraction rate and different solvents (such as 80% methanol, dichloromethane, ethyl acetate, and an extraction with both dichloromethane and ethyl acetate solvents) using two extraction methods (liquid-liquid extraction and solid-phase extraction) to remove matrix interference. An ultraperformance liquid chromatography-mass spectrometer (UPLC-MS) method was used for quantitative and changing analysis of 5-HMF in different ginseng samples. The results indicated that the content of 5-HMF increased dramatically with heating temperature and time, and the 5-HMF in the ginseng samples ranged from 0.01 to 112.32 g/kg protein. The highest value was observed in the honey-added ginseng samples with the highest amount of addition and highest temperature treatment, and the lowest value was found in the fresh ginseng samples. These results implied that 5-HMF may be as an indicator to estimate the honey addition level and heat treatment degree during the processing of ginseng products, and the content of 5-HMF is a promising parameter to evaluate the quality of products (ginseng). The production and regulation of potentially harmful Maillard reaction products (PHMRPs)-5-HMF in ginseng manufacture will provide an important reference for safe ginseng processing.

A novel fluorescence "turn off-on" nanosensor for sensitivity detection acid phosphatase and inhibitor based on glutathione-functionalized graphene quantum dots.

In this paper, we developed a label-free and sensitive fluorescence sensor for acid phosphatase (ACP) and its inhibitor parathion-methyl (PM) detection based on glutathione-functionalized graphene quantum dots (GQDs@GSH). Upon addition of MnO2 nanosheets, the fluorescence of GQDs@GSH could be efficiently quenched via a fluorescence resonance energy transfer. ACP could easily catalyze the hydrolysis of L-Ascorbic acid-2-phosphate (AAP) to ascorbic acid (AA), which could reduce MnO2 nanosheets to Mn2+ in acidic environment, leading to dramatically increase of the fluorescence intensity of GQDs@GSH. Quantitative detection of ACP in a broad range from 0.1 to 9 mU mL-1 with a detection limit of 0.027 mU mL-1 could be achieved. The feasibility of the proposed sensor in real samples analysis was also studied and satisfactory results were obtained. Furthermore, the fluorescence assay strategy could also be used for the detection of parathion-methyl (PM) as ACP inhibitor.

A novel fluorimetric sensing strategy for highly sensitive detection of phytic acid and hydrogen peroxide.

In this paper, we developed a sensitive sensor for phytic acid (PA) and hydrogen peroxide (H2O2) detection based on glutathione-functionalized graphene quantum dots (GQDs@GSH). The fluorescence of GQDs@GSH was found to be effectively quenched by Fe3+ ions via photo-induced electron transfer (PET) process. Upon the addition of PA to GQDs@GSH/Fe3+ system, the fluorescence of GQDs@GSH was significantly restored due to the strong chelating and reducing ability of PA, Fe3+ ions could be reduced to Fe2+ ions by PA and formed PA/Fe2+ complex. Therefore, the "off-on" fluorescence method was constructed to detect PA by using GQDs@GSH/Fe3+ as a fluorescent probe. Furthermore, the method can be used for the detection of H2O2. H2O2 can destroy the chelate structure of PA/Fe2+, release Fe2+ ions and oxidize Fe2+ ions to produce Fe3+ ions, leading to the fluorescence quenching of GQDs@GSH again. Under optimal conditions, the fluorescence sensing platform showed good linear relationship between the relative fluorescence intensity I/I0 and the concentration of PA and H2O2 in the range of 0.05-3 µmol L-1 and 0.5-10 µmol L-1, respectively. The detection limits of PA and H2O2 were 14 nmol L-1 and 0.134 µmol L-1, respectively. Furthermore, the fluorescence assay method was also applied in real sample analysis and satisfactory results were obtained.

A novel fluorescence biosensor for sensitivity detection of tyrosinase and acid phosphatase based on nitrogen-doped graphene quantum dots.

In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, l-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to l-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone. Thus, a novel fluorescence biosensor for the detection of TYR and ACP activity based on N-GQDs was constructed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of TYR and ACP in the range of 0.43-3.85 U mL-1 and 0.04-0.7 mU mL-1 with a detection limit of 0.15 U mL-1 and 0.014 mU mL-1, respectively. The feasibility of the proposed biosensor in real samples assay was also studied and satisfactory results were obtained.