Photodegradation of the pure and formulated scoparone in liquid solutions: kinetics and mechanism.

Scoparone (hereafter SPR) is a prominent candidate of plant-derived acaricide. The photodegradation of the pure SPR was first investigated under different light sources, initial concentrations, pH values, temperatures, organic solvents, aqueous media, and the photolytic characteristics of its formulation in pure water were also studied. The photodegradation rates of pure SPR under different light sources showed the following sequence: 28 W ultraviolet lamp (0.3045 h-1) > 500 W xenon lamp (0.1094 h-1) > 300 W xenon lamp (0.0312 h-1). Under the irradiation of 500 W xenon lamp, the lower initial SPR concentrations, higher pH value, and higher temperatures increased the photodegradation rates of SPR, especially, when the temperature increased higher than 35℃, the degradation rate of SPR increased slowly and maintained at a stable level, the pH and temperatures had small effects on the photodegradation of SPR. The photodegradation rates of pure SPR in organic decreased comparing to in aqueous media. The removal efficiency of 98% SPR technical material (TC) was higher than 5% SPR emulsifiable concentrate (EC) in pure water, indicating that the components present in formulated SPR greatly affected the photodegradation kinetics. Detecting the photoproducts by HPLC/ESI-MS indicated that three main types of reaction including photorearrangement, photohydrolysis, and photooxidation occurred in the photodegradation of SPR at aqueous solution. These results will be helpful for the rational use of SPR and provide a scientific reference for environmental risk evaluation of SPR.

The diagnostic value of dynamic volume computed tomography angiography in children with anomalous origin of the left coronary artery from the pulmonary artery.

There have been almost no reports on the technique of dynamic volume computed tomography angiography (DVCTA) in children with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA). Twelve children with ALCAPA, aged 5 months to 15 years, were enrolled in this retrospective study to explore the clinical value of DVCTA in the diagnosis of ALCAPA in children. All patients underwent low-dose prospective ECG-gated 320-slice DVCTA and transthoracic echocardiography. Two radiologists evaluated the image quality of the DVCTA and recorded the radiation dose at the same time. The accuracy of DVCTA in the diagnosis of ALCAPA was 100%, with the left coronary artery (LCA) opening in the left wall of the pulmonary artery in 4 cases (33.3%), the right wall in 2 cases (16.7%), and the posterior wall in 6 cases (50.0%). All children completed 320-slice DVCTA at a single timepoint; all of the images were diagnosable, and the subjective score was 3.3±0.6, with good consistency between the evaluations performed by the two radiologists (k=0.79). From the echocardiographs of these cases, 4 cases (33.3%) of ALCAPA were diagnosed correctly, 4 cases (33.3%) were misdiagnosed as LCA-pulmonary artery fistula, and 4 cases (33.3%) were missed, including a small LCA that was not displayed in 2 cases. The average CT radiation dose was 0.83±0.57 mSv. Low-dose DVCTA clearly showed the origin, course, and collateral vessels of ALCAPA and could be used reliably for noninvasive diagnosis of ALCAPA in children.

Functional analysis of an upregulated calmodulin gene related to the acaricidal activity of curcumin against Tetranychus cinnabarinus (Boisduval).

BACKGROUND: Curcumin is a promising botanical acaricidal compound with activity against Tetranychus cinnabarinus. Calmodulin (CaM) is a key calcium ion (Ca2+ ) sensor that plays a vital role in calcium signaling. Overexpression of the CaM gene with inducible character occurs in curcumin-treated mites, but its functional role remains to be further analyzed by RNA interference (RNAi) and protein expression. RESULTS: A CaM gene was cloned from T. cinnabarinus (designated TcCaM). TcCaM was upregulated and the protein was activated in mites by curcumin. The susceptibility of mites to curcumin was decreased after inhibiting CaM function with anti-CaM drug trifluoperazine (TFP) and silencing CaM transcription with RNAi, suggesting that the CaM gene is involved in the acaricidal activity of curcumin against mites. Moreover, the TFP pre-treated Sf9 cells were resistant to curcumin-mediated increase in [Ca2+ ]i levels, indicating that CaM-mediated Ca2+ homeostasis was disturbed by curcumin. TcCaM was then re-engineered for heterologous expression in Escherichia coli. Strikingly, our results showed that the recombinant CaM protein was directly activated by curcumin via inducing its conformational changes, its half-maximal effective concentration (EC50 ) value is 0.3 µmol L-1 in vitro, which is similar to curcumin against CaM-expressing Sf9 cells (0.76 µmol L-1 ) in vivo. CONCLUSION: These results confirm that the overexpressed CaM gene is involved in the acaricidal activity of curcumin, and the mode of action of curcumin may be via activating CaM function, and thereby disrupting Ca2+ homeostasis in T. cinnabarinus. This study highlights the novel target mechanism of new acaricides, promoting our understanding of the molecular mechanism of CaM-mediated acaricide targets in mites.

Molecular characterization of a voltage-gated calcium channel and its potential role in the acaricidal action of scopoletin against Tetranychus cinnabarinus.

The carmine spider mite, Tetranychus cinnabarinus (Boisduval), is a polyphagous agricultural pest with an extensive host plant range. Scopoletin is a promising acaricidal compound whose acaricidal mechanism may occur by disrupting intracellular Ca2+ homeostasis and calcium signaling pathways. However, the underlying mechanism of scopoletin for specific target locations of T. cinnabarinus remains unclear. In this study, a full-length cDNA of the L-type voltage-gated calcium channel (TcLTCC) subunit gene from T. cinnabarinus was cloned and characterized. The expression pattern of the TcLTCC gene in all developmental stages of T. cinnabarinus was analyzed. The gene was highly expressed in larval and nymphal stages and was significantly upregulated after treatment with scopoletin. Knocking down the TcLTCC transcript reduced the sensitivity of T. cinnabarinus to scopoletin. Homology modeling and molecular docking were also conducted. The interaction between scopoletin and TcLTCC showed that scopoletin inserted into the cavity bound to the site of the TcLTCC protein by the driving force of hydrogen bonding. This study provides insights into the mechanism by which scopoletin interacts with TcLTCC. Results can improve the understanding of the toxicity of scopoletin to T. cinnabarinus and provide valuable information for the design of new LTCC inhibitors.

Analysis of the Physicochemical Properties of Acaricides Based on Lipinski's Rule of Five.

This study aimed to explore the similarity between the physical and chemical properties of different acaricides, determine whether Lipinski's Rule of Five (RO5) used in the design of drug molecules is suitable for screening acaricides, and provide methods for selection of new acaricides. We evaluated and predicted the molecular properties of >180 acaricides using Molinspiration. We calculated physicochemical property parameters, such as log p, molecular weight (MW), and number of hydrogen bond donors (HBDs), hydrogen bond acceptors (HBAs), and rotatable bonds (Rot B). We then conducted qualitative and quantitative analyses of the physicochemical properties of acaricides. The MW of all acaricides ranged from 141 to 663, with an average value of 337.8. The number of HBDs ranged from 0 to 5, with an average value of 0.46. The number of HBAs ranged from 0 to 9, with an average value of 4.07. The log p ranged from -0.79 to 8.74, with an average value of 4.61. The number of Rot B ranged from 0 to 14, with an average value of 5.62. Except for the microbial and plant-derived acaricides, the molecular properties of the remaining acaricides are in accordance with the Lipinski's RO5. Therefore, the Lipinski's RO5 can provide a basis for screening new acaricide drugs.

Silencing T-type voltage-gated calcium channel gene reduces the sensitivity of Tetranychus cinnabarinus (Boisduval) to scopoletin.

Tetranychus cinnabarinus (Boisduval) is a major pest that harms crops and vegetables worldwide. Scopoletin is a promising acaricidal compound. Our previous study demonstrated that the acaricidal mechanism of scopoletin may be via disrupting intracellular Ca2+ homeostasis and calcium signaling pathway. However, the mechanism underlying the specific target location of scopoletin against T. cinnabarinus remains unclear. In this study, the full-length cDNA of the calcium channel (TcT-VDCC) gene from T. cinnabarinus was cloned and characterized. The TcT-VDCC gene is expressed at all developmental stages of T. cinnabarinus but is highly expressed in the larval and nymphal stages. The TcT-VDCC gene was significantly upregulated after treatment with scopoletin, and the RNAi method was used to feed the dsRNA in T. cinnabarinus to silence the TcT-VDCC gene and reduce its sensitivity to scopoletin. The results showed that the acaricidal mechanism of scopoletin on T. cinnabarinus may be related to TcT-VDCC.

Synthesis and Acaricidal Activities of Scopoletin Phenolic Ether Derivatives: QSAR, Molecular Docking Study and in Silico ADME Predictions.

Thirty phenolic ether derivatives of scopoletin modified at the 7-hydroxy position were synthesized, and their structures were confirmed by IR, ¹H-NMR, 13C-NMR, MS and elemental analysis. Preliminary acaricidal activities of these compounds against female adults of Tetranychus cinnabarinus (Boisduval) were evaluated using the slide-dip method. The results indicated that some of these compounds exhibit more pronounced acaricidal activity than scopoletin, especially compounds 32, 20, 28, 27 and 8 which exhibited about 8.41-, 7.32-, 7.23-, 6.76-, and 6.65-fold higher acaricidal potency. Compound 32 possessed the the most promising acaricidal activity and exhibited about 1.45-fold higher acaricidal potency against T. cinnabarinus than propargite. Statistically significant 2D-QSAR model supports the observed acaricidal activities and reveals that polarizability (HATS5p) was the most important parameter controlling bioactivity. 3D-QSAR (CoMFA: q² = 0.802, r² = 0.993; CoMSIA: q² = 0.735, r² = 0.965) results show that bulky substituents at R4, R1, R2 and R5 (C6, C3, C4, and C7) positions, electron positive groups at R5 (C7) position, hydrophobic groups at R1 (C3) and R2 (C4), H-bond donors groups at R1 (C3) and R4 (C6) will increase their acaricidal activity, which provide a good insight into the molecular features relevant to the acaricidal activity for further designing novel acaricidal agents. Molecular docking demonstrates that these selected derivatives display different bide modes with TcPMCA1 from lead compound and they interact with more key amino acid residues than scopoletin. In silico ADME properties of scopoletin and its phenolic ether derivatives were also analyzed and showed potential to develop as good acaricidal candidates.

3D-QSAR and Molecular Docking Studies on the TcPMCA1-Mediated Detoxification of Scopoletin and Coumarin Derivatives.

The carmine spider mite, Tetranychus cinnabarinus (Boisduval), is an economically important agricultural pest that is difficult to prevent and control. Scopoletin is a botanical coumarin derivative that targets Ca2+-ATPase to exert a strong acaricidal effect on carmine spider mites. In this study, the full-length cDNA sequence of a plasma membrane Ca2+-ATPase 1 gene (TcPMCA1) was cloned. The sequence contains an open reading frame of 3750 bp and encodes a putative protein of 1249 amino acids. The effects of scopoletin on TcPMCA1 expression were investigated. TcPMCA1 was significantly upregulated after it was exposed to 10%, 30%, and 50% of the lethal concentration of scopoletin. Homology modeling, molecular docking, and three-dimensional quantitative structure-activity relationships were then studied to explore the relationship between scopoletin structure and TcPMCA1-inhibiting activity of scopoletin and other 30 coumarin derivatives. Results showed that scopoletin inserts into the binding cavity and interacts with amino acid residues at the binding site of the TcPMCA1 protein through the driving forces of hydrogen bonds. Furthermore, CoMFA (comparative molecular field analysis)- and CoMSIA (comparative molecular similarity index analysis)-derived models showed that the steric and H-bond fields of these compounds exert important influences on the activities of the coumarin compounds.Notably, the C3, C6, and C7 positions in the skeletal structure of the coumarins are the most suitable active sites. This work provides insights into the mechanism underlying the interaction of scopoletin with TcPMCA1. The present results can improve the understanding on plasma membrane Ca2+-ATPase-mediated (PMCA-mediated) detoxification of scopoletin and coumarin derivatives in T. cinnabarinus, as well as provide valuable information for the design of novel PMCA-inhibiting acaricides.

Graphene Oxide Induces Toxicity and Alters Energy Metabolism and Gene Expression in Ralstonia solanacearum.

Graphene oxide (GO) is a promising material for development as an antibacterial, phytoprotective agent due to its contact-based antibacterial activity induced by its physical and chemical properties. However, the mechanism underlying the antibacterial effect of GO has yet to be elucidated. In the current study, we investigated the effects of GO on the phytopathogen R. solanacearum at the molecular level with a specific focus on energy metabolism. Under controlled conditions, the bacteriostatic and bactericidal actions of GO were investigated with respect to concentration, treatment time and rotation speed. Transmission electron microscopy (TEM) and destabilization assays revealed that GO caused injury to bacterial cell membrane structures. Furthermore, adenosine triphosphate (ATP) levels decreased after exposure to sheets of GO, while malondialdehyde levels significantly increased, indicating the occurrence of lipid oxidation. A series of genes related to bacterial virulence, motility and oxidative stress were selected to evaluate the molecular mechanism underlying GO's effects on R. solanacearum. Using quantitative reverse transcription polymerase chain reaction (RT-qPCR), we showed that in the presence of GO, the expression levels of genes involved in virulence and motility were down regulated, with the exception of popA. The phcA, hrpB and flgG genes were significantly downregulated by 2.61-, 3.45- and 4.22-fold, respectively. Conversely, the expression levels of sodB, oxyR and dps, three important oxidative stress genes, were upregulated by 1.82-, 2.17-, and 3.79-fold, respectively. These findings confirmed that cell membrane damage and oxidative stress were responsible for the antibacterial actions of GO, in addition to disturbances to energy metabolism processes.

Synergistic inhibitory effect of scopoletin and bisdemethoxycurcumin on Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae).

The study aimed to investigate the synergistic activity of scopoletin and bisdemethoxycurcumin (BDMC) against the carmine spider mite Tetranychus cinnabarinus. The acaricidal activities of mixtures of scopoletin and BDMC against T. cinnabarinus female adults were measured via slide dipping and leaf disc dipping. A mathematical model was established by SPSS software. Bioassays for multiple effects including contact, ovicidal, cowpea root intake, repellency and oviposition inhibitory activity were carried out. The optimal mass ratio of the mixture of scopoletin and BDMC (at their respective LC(50)), the median lethal concentration (LC(50)) and the co-toxicity coefficient were 7:6, 0.19 mg/mL and 129, respectively. LC(50) values of contact activities of the mixture at optimal ratio against adults, nymphs, larvae, and eggs were 0.19, 0.18, 0.06, and 1.52 mg/mL, respectively. LC(50) values of cowpea root intake activity against adults and nymphs were 5.62 and 6.52 mg/mL, respectively. The highest repellent rates against adults and nymphs were 69.5% and 72.5%, respectively. The mixture of scopoletin and BDMC at the optimal mass ratio possessed strong acaricidal activity against T. cinnabarinus at various developmental stages.

[Lethal effects of scopoletin and bisdemethoxycurcumin against Tetranychus cinnabarinus Boisd. (Acari: Tetranychidae): a simulation study].

By using slide-dip bioassay method under laboratory condition, an investigation was made on the lethal effects of scopoletin, bisdemethoxycurcumin (BDMC), and their combination at an optimal mass ratio (7:6) of scopoletin to BDMC against the adult females of Tetranychus cinnabarinus Boisd. A time-dose mortality model (TDM) was established, which passed the Hosmer-Lemeshow test. The sensitivity of the adult females to the concentration change of the acaricides was in the sequence of scopoletin > optimal mass ratio of scopoletin to BDMC > BDMC. The peak mortality of the female adults was found at 32, 28 and 32 h after treated with BDMC, scopoletin, and their combination at the optimal mass ratio, respectively. The values of the LC50 and LC90 at 48 h after treated with BDMC, scopoletin, and their combination at the optimal mass ratio were 0.3324, 0.2035 and 0.2195 mg x mL(-1), and 2.1198, 0.9521 and 1.1617 mg x mL(-1), and the median lethal time (LT50) of BDMC, scopoletin, and their combination at the optimal mass ratio was 7.4, 6.0 and 6.1 h at the concentration 1.0 mg x mL(-1), and 6.4, 4.8 and 5.0 h at the concentration 2.0 mg x mL(-1), respectively. The acaricidal activity and time-dose response of the optimal combination of scopoletin and BDMC were closer to those of scopoletin, suggesting a synergistic acaricidal activity of the combination of scopoletin and BDMC, which was worthy to be developed for application.