Two-step synthesis of vicinal trifluoromethyl primary amines from α-(trifluoromethyl)styrenes and phthalimide.

A novel two-step synthesis of ß-trifluoromethyl primary amines from readily available α-(trifluoromethyl)styrenes and phthalimide is developed. The first step involves a hydroamination between α-(trifluoromethyl)styrenes and phthalimide (PhthNH) with the assistance of a base. Next, the hydrazinolysis of the resulting N-(ß-trifluoromethyl-ß-arylethyl)phthalimides with hydrazine hydrate affords the desired N-(ß-trifluoromethyl-ß-arylethyl)amines.

Exposure to emamectin benzoate confers cytotoxic effects on human molt-4 T-cells and possible ameliorative role of vitamin E and dithiothreitol.

Emamectin benzoate (EMB) is an avermectin insecticide that is extensively used for pest control, but there are few reports concerning its cytotoxic effects on human lymphocytes. In the current study, the hematotoxicity of EMB was evaluated in Molt-4 T-cells, a human T-lymphoblastic cell line with high motility, and the role of vitamin E (VitE) and dithiothreitol (DTT) in attenuating EMB cytotoxicity was characterized. Exposure of Molt-4 cells to EMB decreased cell viability and proliferation, induced a loss of cell clusters, and significantly increased membrane collapse and chromatin condensation. Moreover, EMB significantly increased cell death and suppressed transglutaminase activity. EMB treatment modulated the NF-κB signaling pathway, decreased the expression of p105, p50, and p65/RelA in cytosolic and nuclear fractions, and increased nuclear IκBα expression. EMB increased oxidative stress, as demonstrated by a significant increase in the levels of reactive oxygen species (ROS). Treatment with non-cytotoxic concentrations of VitE or DTT ameliorated the hematotoxicity induced by pretreatment with EMB, increased Molt-4 cell viability, raised the IC50 values of EMB, limited intracellular ROS generation, and mitigated EMB-mediated effects on NF-κB signaling. The results indicate the potential cytotoxicity of EMB on human lymphocytes, and demonstrate that VitE and DTT treatment can reduce the cytotoxic effects of EMB.

Synergy of cystamine and pyraclostrobin against Fusarium graminearum involves membrane permeability mitigation and autophagy enhancement.

The application of fungicide mixture is one of the most important measures to extend the service life of highly selective fungicides. Pyraclostrobin (PYR), which has been extensively used to control plant diseases by inhibiting mitochondrial respiration of pathogenic fungi, is at a high risk of resistance development. In this study, the potential of PYR alone or in combination with cystamine, an inhibitor of microbial transglutaminase, to suppress Fusarium graminearum was tested in vitro and in vivo. A synergistic effect of PYR/CYS mixture was observed both in vitro and when applied to etiolated wheat coleoptile. The control effect of PYR/CYS mixture on F. graminearum was better than that of PYR alone, which was reflected by the increased protection effect. The discrepancies of membrane permeability and the redox-physiological state were observed between PYR and PYR/CYS treatments, suggesting that an increased PYR availability in F. graminearum mycelia could be related with the observed synergistic action. Moreover, a synergistic profile was observed between PYR and CYS in regard of massive autophagosomes in mycelia, indicating that enhanced autophagy could be involved in the mode of action of PYR/CYS mixture. The differential content of mitochondrial metabolites between PYR and PYR/CYS treatments also provided evidence for CYS contribution to the fungicidal action of PYR/CYS mixture. The results provide insight into the synergistic mechanism of action of PYR/CYS mixture and an effective way to enhance the efficiency of PYR to combat F. graminearum.

Safety assessment of a new benzoylphenylurea TXH09 and its efficacy against two borers Ostrinia furnacalis and Grapholitha molesta in field.

Benzoylphenylureas as an important type of insect growth regulators, acting on the moulting stage in immature insects, are highly effective and low toxic. The new benzoylphenylurea TXH09 [N-((2,6-dimethyl-4-(heptafluoropropyl-2-yl)phenyl)carbamoyl)-2,6-difluorobenzamide] has high efficacy against chewing insect pests harming vegetables and rice. In this paper, the efficacy of TXH09 against two intractable borers Ostrinia furnacalis and Grapholitha molesta were evaluated in field, and safety assessment by exploring the characteristics of photodegradation, cytotoxicity, micronucleus generation and chromosome aberration was performed. The results showed that TXH09 had good capability in preventing infested corn and reducing the population of O. furnacalis larvae, and maintained high efficacy on shoot protection and peach conservation against G. molesta larvae. There were no significant differences between the control effects of TXH09 and that of hexaflumuron or diflubenzuron at the same active dose. TXH09 photolysis in solvents N,N-dimethylformamide, toluene and methanol yielded two major products, and the photodegradation of TXH09 was more prone to occur in N,N-dimethylformamide. TXH09 and the mixture of its photoproducts showed higher cytotoxicity on insect Sf-9 cells than on human Hek293 cells. Moreover, TXH09 didn't show significant effects in inducing micronucleated cells in both male and female mice and chromosomal aberrations in mouse spermatocytes by its own. In conclusion, TXH09, as an effective insecticide, has good environmental safety performance against O. furnacalis and G. molesta in field.

Comparative cytotoxic effects of five commonly used triazole alcohol fungicides on human cells of different tissue types.

The widespread application of triazole fungicides makes people attach great concern over its adverse effects in mammalian. In this paper, cytotoxic effects of triazole alcohol fungicides (TAFs) were assessed on human HeLa, A549, HCT116 and K562 cells, and the potential mechanism of TAFs cytotoxicity was studied preliminarily. Results showed that TAFs had cytotoxicity on human cells with different level and cytotoxic selectivity. TAFs cytotoxicity was resonated with a typical hormetic biphasic dose action that produced a complex pattern of stimulatory or inhibitory effects on cell viability. Among the five TAFs, diniconazole revealed a widest range of cytotoxicity to inhibit the viability of the adherent and the suspension cells, causing HeLa cells shrinkage, A549 cells shrunken, and K562 cells collapse, and showed stronger cytotoxicity than hexaconazole. Moreover, the involvement of ROS generation in the cytotoxicity of TAFs on human cells was observed, and the apoptosis of HeLa cells and the formation of apoptotic body in K562 cells induced by diniconazole were characterized. The results indicated the cytotoxicity of TAFs with different structures on human cells was depended on their own property and cell specificity, K562 cells were the most susceptible to TAFs and diniconazole was the strongest toxic.

The effect of α-tocopherol and dithiothreitol in ameliorating emamectin benzoate cytotoxicity in human K562 cells involving the modulation of ROS accumulation and NF-κB signaling.

Emamectin benzoate (EMB) toxicity contributes a potential risk to environment and human health. To investigate the effect of α-tocopherol (VitE) and dithiothreitol (DTT) in ameliorating EMB-induced cytotoxicity in human K562 cells, in vitro cultured human K562 cells were incubated with different concentrations of EMB in supplement with VitE and DTT when the cells were in the logarithmic phase. Next, the cell growth inhibition was evaluated using the MTT assay and cellular morphology observation. Reactive oxygen species (ROS) production was monitored using DCFH-DA probe and NF-κB signaling was determined using Western blotting. The results demonstrated that treatment with EMB (time- and concentration-dependent) showed significantly greater inhibition on K562 cell viability, heavier chromatin condensation and DNA fragmentation, and stronger suppression of NF-κB/p105 and p65/RelA expression of K562 cells than the control group (p < 0.01). The supplementation of VitE or DTT could help protect K562 cells against EMB-induced cytotoxicity by improving cell viability, preventing ROS accumulation and up-regulating NF-κB signaling through their ameliorating effects against oxidative stress induced by EMB. VitE had a stronger synergistic effect in limiting EMB cytotoxicity than DTT. Our findings indicate that VitE and DTT are potent antioxidants for human K562 cells, offering a promising means of ameliorating EMB cytotoxicity.

Cytotoxic selectivity and apoptosis induction of piericidin A contributes potentially to its insecticidal effect against Mythimna separata (Lepidoptera: Noctuidae) larvae.

Piericidin A (PIA), an active inhibitor of Complex I, is widely used in studies of the anti-bacterial and anti-disease competence, but its physiological and mechanistic effects have rarely been clearly defined in insect individual or insect cells. The present study reveals the considerable insecticidal activity of PIA on Mythimna separata larvae by using a comparison with Aphis craccivora adult, and the cytotoxic selectivity induced by PIA on lepidopteran Tn5B1-4 cells. We demonstrate that the viability of Tn5B1-4 cells is inhibited by PIA in a time- and concentration-dependent manner with IC50 value of 0.061 µM, whilst PIA shows slight inhibitory effect on the viability of HepG2 and Hek293 cells with IC50 value of 233.97 and 228.96 µM, respectively. The inhibitory effect of PIA on the proliferation of Tn5B1-4 cells is significant and persistent, causing a series of morphological changes including cell shrinkage, condensed and fragmented nuclei. Intracellular biochemical assays show that PIA induces apoptosis of Tn5B1-4 cells coincides with a decrease in the mitochondrial membrane potential. PIA in Tn5B1-4 cells can be chelated by EDTA, thereby losing cytotoxicity, whereas exogenous Ca2+ restores the cytotoxicity of PIA by chelating with EDTA in a competitive manner. Our findings highlight the importance of the long-lasting cytotoxicity and the cytoxic selectivity on Tn5B1-4 cells caused by PIA, which ensure the identification of insecticidal effect of PIA against insect pests.

A comparative assessment of cytotoxicity of commonly used agricultural insecticides to human and insect cells.

The cytotoxic potential of 13 commonly used agricultural insecticides was examined using cell-based systems with three human HepG2, Hek293, HeLa cells and three insect Tn5B1-4, Sf-21, and Drosophila S2 cells. Data showed that (1) an enhancement of some insecticides (e.g. pyrethroids) on cells proliferation; (2) an inhibition of some insecticides on cells viability; (3) various levels of susceptibility of different cells to the same insecticide; and (4) the cell type dependent sensitivity to different insecticides. The degree of cytotoxicity of insecticides on human cells was significantly lower than that on insect cells (P<0.05). Methomyl, even 20µg/ml, showed little cytotoxicity at 24h exposure whereas emamectin benzoate possessed the strongest cytotoxic potential in a dose-dependent fashion. The results revealed comparable cytotoxic property of agricultural insecticides against intact cells.

Antioxidative cellular response of lepidopteran ovarian cells to photoactivated alpha-terthienyl.

Photodynamic sensitizers as useful alternative agents have been used for population control against insect pests, and the response of insect ovarian cells towards the photosensitizers is gaining attention because of the next reproduction. In this paper, antioxidative responses of lepidopteran ovarian Tn5B1-4 and Sf-21 cells to photoactivated alpha-terthienyl (PAT) are investigated. PAT shows positive inhibitory cytotoxicity on the two ovarian cells, and its inhibition on cell viability is enhanced as the concentrations are increased and the irradiation time is extended. Median inhibitory concentrations (IC50) are 3.36µg/ml to Tn5B1-4 cells, and 3.15µg/ml to Sf-21 cells at 15min-UV-A irradiation 2h-dark incubation. Under 10.0µg/ml PAT exposure, 15min-UV-A irradiation excites higher ROS production than 5min-UV-A irradiation does in the ovarian cells, the maximum ROS content is about 7.1 times in Tn5B1-4 cells and 4.3 times in Sf-21 cells, and the maximum malondialdehyde levels in Tn5B1-4 and Sf-21 cells are about 1.47- and 1.36-fold higher than the control groups, respectively. Oxidative stress generated by PAT strongly decreases the activities of POD, SOD and CAT, and induces an accumulation of Tn5B1-4 cells in S phase and Sf-21 cells in G2/M phase in a concentration-dependent fashion. Apoptosis accumulation of Tn5B1-4 cells and the persistent post-irradiation cytotoxicity are further observed, indicating different antioxidative tolerance and arrest pattern of the two ovarian cells towards the cytotoxicity of PAT.

Calycosin suppresses expression of pro-inflammatory cytokines via the activation of p62/Nrf2-linked heme oxygenase 1 in rheumatoid arthritis synovial fibroblasts.

The activation of synovial fibroblasts (SFs) and the subsequent production and expression of pro-inflammatory cytokines play a crucial role in the pathogenesis and progression of rheumatoid arthritis (RA). In the current study, rheumatoid arthritis synovial fibroblasts (RASFs) isolated from the joint of the patients were used to evaluate the suppressive effects of calycosin (CAL), a compound derived from the Chinese medicinal herb Radix Astragali, on the expression of pro-inflammatory cytokines in RASFs. The results demonstrated that increased mRNA expression levels of interleukin-1ß (IL-1ß), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-25 (IL-25), interleukin-33(IL-33) were significantly inhibited by CAL. Furthermore, the compound obviously suppressed IL-6 and IL-33 secretion. The key inflammatory mediator, cyclooxygenase-2 (COX-2) was significantly attenuated by CAL. A mechanistic study showed that the antioxidant enzymes heme oxygenase-1 (HO-1), NAD(P)H dehydrogenase quinone 1(NQO1) and Nrf2 of RASFs were markedly activated by CAL. Furthermore, CAL potentiated the accumulation of sequestosome 1 (SQSTM1, p62) and the degradation of Kelch-like ECH-associated protein 1 (Keap1), thereby inducing Nrf2 translocation from the cytoplasm to the nucleus. Thus, CAL suppresses the expression of pro-inflammatory cytokines via p62/Nrf2-linked HO-1 induction in RASFs, which suggests that the compound should be further investigated as a candidate anti-inflammatory and anti-arthritic agent.

Design and synthesis of thiourea derivatives with sulfur-containing heterocyclic scaffolds as potential tyrosinase inhibitors.

Tyrosinase is a key enzyme during the production of melanins in plants and animals. A class of novel N-aryl-N'-substituted phenylthiourea derivatives (3a-i, 6a-k) were designed, synthesized and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were evaluated. The results showed some 4,5,6,7-tetrahydro-2-[[(phenylamino)thioxomethyl]amino]-benzo[b]thiophene-3-carboxylic acid derivatives (3a-i) exhibited moderate inhibitory potency on diphenolase activity of tyrosinase. When the scaffold of 4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylic acid was replaced with 2-(1,3,4-thiadiazol-2-yl)thio acetic acid, the inhibitory activity of compounds (6a-k) against tyrosinase was improved obviously; especially, the inhibitory activity of compound 6h (IC50=6.13 µM) is significantly higher than kojic acid (IC50=33.3 µM). Moreover, the analysis on inhibition mechanism revealed that compound 6h might plays the role as a noncompetitive inhibitor.

The competence of hemocyte immunity in the armyworm Mythimna separata larvae to sublethal hexaflumuron exposure.

Hemocytes circulating in the hemolymph are essential for the insect immunity to protect insects against infections. The effects of sublethal hexaflumuron exposure on the competence of hemocyte immunity of fifth-instar larvae of Mythimna separata were investigated. In this insect, the sublethal exposure could cause plasmatocyte filopodia to contract and shorten, and granulocytes to compact with a loss of cytoplasmic projections in vitro, and induce granulocytes to swell and expand in vivo. The mean number of total hemocytes was significantly declined in feed-thru larvae by 5.0µgmL(-1) hexaflumuron. Changes in proportional counts of hemocytes showed that sublethal hexaflumuron exposure caused a decrease of granulocytes and an increase of plasmatocytes in a concentration-dependant manner, but these changes were time-dependently reduced. Few effects of the sublethal exposure were revealed on the proportional counts of spherulocytes, oenocytoids, and prohemocytes. The exposure at 24h showed strong inhibition on phenoloxidase activity in plasma and hemocytes, but this inhibition was time-dependently weakened. The NADPH-diaphorase staining assays showed that a positive immune response of nitric oxide synthase (NOS) in hemocytes was incited by the sublethal exposure, and the longer-time exposure to the higher concentrations of hexaflumuron caused a heavier loss of NOS activity. Phagocytosis rates revealed the inhibitory effect of sublethal hexaflumuron exposure on the phagocytic ability of granulocytes and plasmatocytes that was significantly greater than the effect of chlorpyrifos at the same concentrations. These results show that sublethal hexaflumuron exposure reduces M. separata larval survival by depressing the competence of hemocyte-mediated immune responses.

Detection on emamectin benzoate-induced apoptosis and DNA damage in Spodoptera frugiperda Sf-9 cell line.

Emamectin benzoate (EMB), an important macrocyclic lactone insecticide that belongs to the avermectin family and possesses excellent potency in controlling pests, is non-carcinogenic and non-mutagenic conducted in rats and mice, but EMB-induced cytotoxicity and genotoxicity in arthropod insect have been seldom reported yet. In the present paper, we quantified the cytotoxicity of EMB through the detections on cell viability, DNA damage, and cell apoptosis in Spodoptera frugiperda Sf-9 cells in vitro. The results showed that EMB caused a concentration- and time-dependent reduction on the viability of Sf-9 cells, and the median inhibitory concentrations (IC50) were 3.34µM at 72h of exposure. The dual acridine orange/ethidium bromide staining showed that exposure to EMB induced a significant time- and concentration-dependent increase on cell apoptosis. The alkaline comet assay revealed that EMB induced significant increases on single-strand DNA breaks, and the percentage of γH2AX-positive cells represented a time- and concentration-dependent formation of DNA double-strand breaks in Sf-9 cells. Interestingly, the similar cytotoxic actions of EMB also went for the human cancerous HeLa cells as a control cell group. Data demonstrated the potential cytotoxic effect of EMB on Sf-9 cells that was significantly greater than the effect of hydrogen peroxide at the same concentrations.

[Treatment of Refractory Rheumatoid Arthritis by Huayu Tongbi Recipe Combined Methotrexate].

OBJECTIVE: To evaluate the clinical efficacy and safety of Huayu Tongbi Recipe (HTR) combined methotrexate (MTX) in treating refractory rheumatoid arthritis (RRA). METHODS: Totally 167 RRA patients were assigned to the treatment group (73 cases) and the control group (94 cases) according to different therapeutic methods. Patients in the treatment group were treated with HTR combined MTX, while those in the control group were treated with leflunomide (LEF) combined MTX. Clinical signs and symptoms, RF, CRP, ESR, disease activity score 28 (DAS28), and safety indicators were compared between the two groups before treatment, at week 12 and 24 after treatment. The efficacy and safety indices were also evaluated. RESULTS: At week 12 after treatment the total effective rate was 82.2% (60/73 cases) in the treatment group and 79.8% (75/94 cases) in the control group, showing no statistical difference between the two groups (chi2 = 0.15, P > 0.05). At week 24 after treatment the total effective rate was 78.1% (57/73 cases) in the treatment group and 755% (71/94 cases) in the control group, showing no statistical difference between the two groups (chi2 = 0.15, P > 0.05). There was statistical difference in the total effective rate between week 24 and week 12 in the control group (chi2 = 0.49, P < 0.05). Clinical signs and symptoms, RF, CRP, ESR, and DAS28 were significantly improved in the two groups after 12- and 24-week treatment (P < 0.01). There was no statistical difference in the improvement at week 12 after treatment between the two groups (P > 0.05). There was statistical difference in time of morning stiffness, tender joint numbers, swollen joint numbers, patient global assessment, RF, CRP, and DAS28 at week 24 after treatment between the two groups (P < 0.05). Besides, adverse reactions occurred less in the treatment group than in the control group (P < 0.01). CONCLUSION: The efficacy of HTR combined MTX was equivalent to that of LEF (10 mg per day) combined MTX, but with more stable therapeutic effects and less adverse reactions.

Tanshinone IIA induces apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis via blockade of the cell cycle in the G2/M phase and a mitochondrial pathway.

Tanshinone IIA (Tan IIA), a phytochemical derived from the roots of Salvia miltiorrhiza BUNGE, has been documented with anti-tumor, pro-apoptotic, and anti-inflammatory activities. Salvia miltiorrhiza has long been used to treat rheumatoid arthritis (RA). Apoptosis induction of RA-fibroblast-like synoviocytes (FLS) was suggested to be a potential therapeutic approach for RA. The aim of this study was to investigate whether Tan IIA promotes apoptosis in RA-affected FLS. In this study, the viability of an immortalized FLS cell line derived from RA patients was assessed by 3-(4,5-dimethylthiazol-2-yl)-5,3-carboxymethoxyphenyl-2,4-sulfophenyl-2H-tetrazolium (MTS) assay after Tan IIA treatment. Apoptosis was measured by terminal deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) assay and flow cytometry. Cell cycle was evaluated by flow cytometry. The expressions of mitochondrial apoptosis-related molecules, including Bcl-2, Bax, mitochondrial cytochrome c (Cyt-c), cytosolic Cyt-c, apoptotic protease activating factor 1 (Apaf-1), procaspase-9, procaspase-3, caspase-9, and caspase-3 were determined by Western blotting. Our data demonstrate that Tan IIA induced apoptosis of RA-FLS, blocked the cell cycle in the G2/M phase, and regulated the protein expression of Bcl-2, Bax, and Apaf-1, the release of mitochondrial Cyt-c, and the activation of caspase-9 and caspase-3. The results support the conclusion Tan IIA treatment likely induces apoptosis of RA-FLS through blockade of the cell cycle in the G2/M phase and a mitochondrial pathway. These data suggest that Tan IIA may have therapeutic potential for RA.

Property of midgut α-amylase from Mythimna separata (Lepidoptera: Noctuidae) larvae and its responses to potential inhibitors in vitro.

Midgut α-amylase is an important digestive enzyme involved in larval energy metabolism and carbohydrate assimilation. In this article, the properties of midgut α-amylase from the Oriental armyworm, Mythimna separata (Lepidoptera: Noctuidae), larvae were characterized, and its in vitro responses to chemical inhibitors were also determined. The kinetic parameters Km and Vmax of midgut α-amylase were 0.064 M, 4.81 U mg pro(-1) in phosphate buffer, and 0.128 M, 1.96 U mg pro(-1) in barbiturate-acetate buffer; α-amylase activity linearly increased as starch concentration increased. α-Amylase activity was not influenced by amino acids such as Pro, Met, Try, His, Ala, and Phe but was strongly activated by antioxidants. Reduced glutathione, 1,4-dithiothreitol, ß-mercaptoethanol, and ascorbic acid improved the activity of α-amylase about 2.06, 3.46, 3.37, and 6.38 times, respectively, relative to the control. Ethylenediaminetetraacetic acid, sodium dodecyl sulfonate, and N-bromosuccinimide (NBS) strongly inhibited α-amylase. α-, ß-, and γ-cyclodextrin were not the preferred substrates for α-amylase. Kinetic analysis showed that IC50 value of NBS against α-amylase was 1.52 (±0.26) µM, and the mode of action of NBS with Ki as 2.53 (0.35) µM was a mixed-type inhibition that indicated a combination of partial competitive and pure noncompetitive inhibition. The midgut α-amylase of armyworm larvae may be a potential target for novel insecticide development and pest control.

Targeting Therapeutic Windows for Rheumatoid Arthritis Prevention.

Rheumatoid arthritis (RA) is a worldwide public health problem. Interventions to delay or prevent the onset of RA have attracted much attention in recent years, and researchers are now exploring various prevention strategies. At present, there is still no unified consensus for RA prevention, but targeting therapeutic windows and implementing interventions for at-risk individuals are extremely important. Due to the limited number of clinical trials on pharmacologic interventions, further studies are needed to explore and establish optimal intervention regimens and effective measures to prevent progression to RA. In this review, we introduce the RA disease process and risk factors, and present research on the use of both Western and Chinese medicine from clinical perspectives regarding RA prevention. Furthermore, we describe several complete and ongoing clinical studies on the use of Chinese herbal formulae for the prevention of RA.

[Regulatory roles of compound danshen in the downstream path of cyclooxygenases in rheumatoid arthritis patients' synovium].

Rheumatoid arthritis (RA) belongs to Bi syndrome (arthralgia) in Chinese medicine. Till now there lacks effective therapeutic methods. Recently cyclooxygenases (COXs) inhibitors, having regulator roles for many pro-inflammatory cytokines, have been widely used in RA treatment. But due to existing cardiovascular risks, researches on targeting the downstream specific factors of COXs have been under discussion. Considering the key role of blood stasis syndrome (BSS) in the pathology of RA and the fact that thromboxane A2 (TXA2) plays a pivotal role in BSS, we theoretically explored possible regulatory roles of Compound Danshen, a representative therapy in blood activating stasis removing method in the downstream path of COXs in synovial cells of RA. We proposed a brand new research direction of RA researches.

Post-synthetic regulation of the fluorescence of CDs: insights into the fluorescence mechanism.

Exploring the origin of emission is fundamental in the field of carbon dots (CDs). Due to the lack of suitable in situ probing techniques, it is necessary to explore effective alternative methods that can accurately reflect the relationship between the emission and the composition of the functional groups of CDs. Herein, we propose a new method of post-synthetic treatment of CDs by photo-oxidation to investigate the origin of emission for CDs. After the addition of a photo-oxidant into pre-prepared CDs under UV irradiation, the fluorescence of CDs can be regulated from the original orange emission to the final green emission due to the damage of original functional groups and the formation of new functional groups on CDs during the post-treatment process. The abundant dynamic information about the functional groups and emissions of CDs during the visible and ready-to-monitor post-treatment process makes it possible to quantitatively analyze the origin of the emission of CDs. Our results suggest that the emission sub-peaks at 560 nm and 600 nm relate to the CD surface-state-associated -NH3+ groups, while the emission sub-peak at 537 nm or 494 nm is associated with the CD surface-state-associated -OH groups or the CD surface-state-associated carbonyl groups (CO). Under UV irradiation, the CD surface-state-associated -NH3+ groups can be continuously converted into the CD surface-state-associated -OH groups and the CD surface-state-associated carbonyl groups (CO), leading to the changed emission color of CDs.

The importance of selecting crystal form for triazole fungicide tebuconazole to enhance its botryticidal activity.

The growing evidences of resistant fungi stimulate fully understanding tebuconazole regarding its crystal structure on fungicidal activity. In this study, the crystal structures of six technical tebuconazoles (BX, HH, JP, QZ, SJ, and YT) were characterized by using high-resolution X-ray powder diffraction and three-dimensional crystal structure modeling. A structure-activity relationship of the tebuconazoles on the susceptible (HLS and YJS) or resistant (XHR) Botrytis cinerea isolates was analyzed, the differential tricarboxylic acid (TCA) cycle metabolism was determined, and molecular docking with sterol 14α-demethylase (CYP51) was performed. The results showed that tebuconazole existed in three types of crystal forms: an overlapping-pair conformation, a side-by-side-pair conformation, and a parallel-pair conformation. QZ with the parallel-pair conformation and the minimum crystal cell volume exhibited a higher activity and a lower resistant level. XHR possessed a higher content of TCA cycle metabolites and phosphate than YJS, but the exposure to QZ significantly reduced the contents of citrate, isocitrate, α-ketoglutarate and oxaloacetate in XHR, as did the exposure to other technical tebuconazoles. Moreover, the point mutations F487L, G464S, and G443S altered the binding properties of chiral stereoscopic R-QZ with CYP51 protein. Especially the G443S mutation promoted a weak linking of R-QZ with LEU380 and TYR126, and greatly slashed the binding action at lower docking score. In conclusion, our results evidenced an efficient crystal conformation of tebuconazole to improve botryticidal activity and a potential adaptability of B. cinerea to tebuconazole inhibition in TCA cycle metabolism and CYP51 protein mutation.