Enhancing catalytic activity of CuCoFe-layered double oxide towards peroxymonosulfate activation by coupling with biochar derived from durian peel for antibiotic degradation: The role of C=O in biochar and underlying mechanism of built-in electric field.

CuCoFe-LDO/BCD was successfully synthesized from CuCoFe-LDH and biochar derived from durian shell (BCD). Ciprofloxacin (CFX) degraded more than 95% mainly by O2•- and 1O2 in CuCoFe-LDO/BCD(2/1)/PMS system within 10 min with a rate constant of 0.255 min-1, which was 14.35 and 2.66 times higher than those in BCD/PMS and CuCoFe-LDO/PMS systems, respectively. The catalytic system exhibited good performance over a wide pH range (3-9) and high degradation efficiency of other antibiotics. Built-in electric field (BIEF) driven by large difference in the work function/Fermi level ratio between CuCoFe-LDO and BCD accelerated continuous electron transfer from CuCoFe-LDO to BCD to result in two different microenvironments with opposite charges at the interface, which enhanced PMS adsorption and activation via different directions. As a non-radical, 1O2 was mainly generated via PMS activation by C=O in BCD. The presence of C=O in BCD resulted in an increase in atomic charge of C in C=O and redistributed the charge density of other C atoms. As a result, strong adsorption of PMS at C atom in C=O and other C with a high positive charge was favorable for 1O2 generation, whereas an enhanced adsorption of PMS at negatively charged C accounted for the generation of •OH and SO4•-. After adsorption, electrons in C of BCD became deficient and were fulfilled with those transferred from CuCoFe-LDO driven by BIEF, which ensured the high catalytic activity of CuCoFe-LDO/BCD. O2•-, on the other hand, was generated via several pathways that involved in the transformation of •OH and SO4•- originated from PMS activation by the transition of metal species in CuCoFe-LDO and negatively charged C in BCD. This study proposed a new idea of fabricating a low-cost metal-LDH and biomass-derived catalyst with a strong synergistic effect induced by BIEF for enhancing PMS activation and antibiotic degradation.

Chemical constituents from the leaves of Sindora siamensis var. maritima and their antimicrobial and α-glucosidase inhibitory activities.

Two new glycosides, sindosides A-B (1-2), along with 11 previously identified metabolites (3-13), were isolated from an ethanolic extract of the leaves of Sindora siamensis var. maritima. The structures of the purified phytochemicals were elucidated by interpreting their spectroscopic data (IR, NMR, and HRMS). The absolute configuration of compound 1 was established by experimental and calculated ECD spectra. The antimicrobial results revealed that compound 8 selectively inhibited C. albicans fungal with a MIC value of 64 µg/mL, whereas 11 presented a weak inhibition toward E. faecalis, S. aureus, and B. cereus bacterial strains with the same MIC value of 128 µg/mL. Interestingly, compounds 1, 2, 8, 9, and 11 showed α-glucosidase inhibitory activity with IC50 values ranging from 14.42 ± 0.21 to 30.62 ± 0.18 µM, which were more active than the positive control (acarbose, with an IC50 value of 46.78 ± 1.37 µM). Enzyme kinetic analysis revealed that compounds 1, 2, and 11 behaved as uncompetitive inhibitors with Ki values of 8.60 ± 1.04, 5.16 ± 0.73, and 7.17 ± 0.98 µM, respectively.

Effective activation of peroxymonosulfate by CoCr-LDH for removing organic contaminants in water: from lab-scale to practical applications.

In this study, CoCr layered double hydroxide material (CoCr-LDH) was prepared and used as an effective catalyst for peroxymonosulfate (PMS) activation to degrade organics in water. The prepared CoCr-LDH material had a crystalline structure and relatively porous structure, as determined by various surface analyses. In Rhodamine B (RhB) removal, the most outstanding PMS activation ability belongs to the material with a Co:Cr molar ratio of 2:1. The removal of RhB follows pseudo-first-order kinetics (R2 > 0.99) with an activation energy of 38.23 kJ/mol and efficiency of 98% after 7 min of treatment, and the total organic carbon of the solution reduced 47.2% after 10 min. The activation and oxidation mechanisms were proposed and the RhB degradation pathways were suggested with the key contribution of O2•- and 1O2. Notably, CoCr-LDH can activate PMS over a wide pH range of 4 - 9, and apply to a wide range of organic pollutants and aqueous environments. The material has high stability and good recovery, which can be reused for 5 cycles with a stable efficiency of above 88%, suggesting a high potential for practical recalcitrant water treatment via PMS activation by heterogeneous catalysts.

Antimicrobial constituents from the leaves of Hibiscus tiliaceus L.

Repeated column chromatography resulted in the isolation of two new megastigmane derivatives, methyl-tiliaceates A and B (1 and 2), along with four known metabolites (3-6) from the leaves of Hibiscus tiliaceus L. The structures of the purified phytochemicals were elucidated by interpreting their NMR, HRESIMS, and CD spectroscopic data, as well as comparison with the previous literature. The compounds isolated were subjected to in vitro antimicrobial assays against a panel of pathogenic microorganisms (Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, and Candida albicans). Compound 1 showed obvious selective inhibition against the B. cereus strain, whereas 3 - 5 showed weak inhibitory activities against E. faecalis and S. aureus bacterial, and C. albicans fungal strains (with MIC values ranging from 128 to 256 µg/mL).

Activity theory as a framework for teaching mathematics: An experimental study.

This article introduces activity theory and how it can be employed to instruct the topic of straight-line equations in a plane - Geometry 10. Using the activity theory approach, we studied and developed a teaching process. The procedure is divided into three stages: Phase 1: Motivation and goal orientation, in which teachers present situations to attract students to the lesson; Phase 2: Knowledge formation, in which students engage in a variety of learning activities to build the knowledge they need to learn; Phase 3: Practice and consolidation, in which many exercises are assigned to students to solve in order to consolidate their knowledge and assist teachers in detecting and correcting students' misconceptions. To examine the effectiveness of applying the proposed three-phase model, we used a two-group pretest-posttest experimental model to determine whether or not teaching with the activity theory approach is more effective than the traditional teaching method by testing four research hypotheses. The experimental teaching took place in the Mo Cay district of Ben Tre province, Vietnam. Both the experimental and control classes began with the same level of mathematics, which was then tested using inferential statistics. After completing the pedagogical experiment, we discovered that students in the experimental class who were taught using activity theory achieved better learning outcomes than students in the control class, who were taught using the traditional teaching method; in the experimental class, the number of weak students decreased in comparison to the original; however, the number of good students did not increase. This is an issue that requires further studies to find ways to influence a wide range of students with different levels of mathematics so that the effectiveness of teaching according to the activity theory approach is improved.

Glycoside constituents from Miliusa sinensis leaves and their anti-inflammatory and acetylcholine protective effects.

Repeated column chromatography resulted in the isolation of two new glycosides, miliusides A-B (1 and 7), along with six known metabolites (2-6, and 8) from the leaves of Miliusa sinensis Finet and Gagnep. The structures of the purified phytochemicals were elucidated by interpreting their spectroscopic data (NMR, HRMS), as well as comparison with the previous literature. The biological evaluation of acetylcholinesterase (AChE) inhibitory effects and anti-inflammatory activity by measuring nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 mouse macrophage cells, were also conducted. Among them, compounds 5 and 7 exhibited significant AChE inhibitory activities (IC50 = 53.36 ± 4.20 and 88.50 ± 8.79 µM, respectively), compared with the positive control (Galanthamine, IC50 = 1.65 ± 0.15 µM). Only the MeOH extract showed suppression effects on NO production in LPS-induced RAW264.7 cells (IC50 = 38.18 ± 3.25 µg/mL) comparable to that of the positive control, l-NMMA (IC50 = 2.21 ± 0.56 µg/mL).

A new triterpenoid from the stems of Kadsura coccinea with antiproliferative activity.

A series of schiartane C29 nortriterpenoids with 5/5/7/6/5 membered consecutive rings (1‒5) with an unique schinortriterpenoid skeleton including a new, kadcoccilactone V (1), together with four known ones (2‒5) and three known triterpenoids (6‒8) were identified from stems of Kadsura coccinea (Lem.) A. C. Smith. The structures of 1 and known compounds were elucidated by interpretation of 1D and 2D NMR, and HR-ESI-MS data as well as comparing those data in the literature. All the isolated compounds were examined for cytotoxic effects against six human cancer cell lines [(HCT-15 (colon), NUGC-3 (stomach), NCI-H23 (lung), ACHN (renal), PC-3 (prostate), and MDA-MB-231 (breast)]. Among them, compound 6 showed potent cytotoxicity against NCI-H23 (GI50 1.28 µM) and NUGC-3 (GI50 1.28 µM), and significantly inhibited on PC-3, MDA-MB-231, ACHN, HCT-15 with GI50 values around 2.33 to 2.67 µM.

The Drought-Mediated Soybean GmNAC085 Functions as a Positive Regulator of Plant Response to Salinity.

Abiotic stress factors, such as drought and salinity, are known to negatively affect plant growth and development. To cope with these adverse conditions, plants have utilized certain defense mechanisms involved in various aspects, including morphological, biochemical and molecular alterations. Particularly, a great deal of evidence for the biological importance of the plant-specific NAM, ATAF1/2, CUC2 (NAC) transcription factors (TFs) in plant adaptation to abiotic stress conditions has been reported. A previous in planta study conducted by our research group demonstrated that soybean (Glycine max) GmNAC085 mediated drought resistance in transgenic Arabidopsis plants. In this study, further characterization of GmNAC085 function in association with salt stress was performed. The findings revealed that under this condition, transgenic soybean plants overexpressing GmNAC085 displayed better germination rates than wild-type plants. In addition, biochemical and transcriptional analyses showed that the transgenic plants acquired a better defense system against salinity-induced oxidative stress, with higher activities of antioxidant enzymes responsible for scavenging hydrogen peroxide or superoxide radicals. Higher transcript levels of several key stress-responsive genes involved in the proline biosynthetic pathway, sodium ion transporter and accumulation of dehydrins were also observed, indicating better osmoprotection and more efficient ion regulation capacity in the transgenic lines. Taken together, these findings and our previous report indicate that GmNAC085 may play a role as a positive regulator in plant adaptation to drought and salinity conditions.

Histidine Kinases: Diverse Functions in Plant Development and Responses to Environmental Conditions.

The two-component system (TCS), which is one of the most evolutionarily conserved signaling pathway systems, has been known to regulate multiple biological activities and environmental responses in plants. Significant progress has been made in characterizing the biological functions of the TCS components, including signal receptor histidine kinase (HK) proteins, signal transducer histidine-containing phosphotransfer proteins, and effector response regulator proteins. In this review, our scope is focused on the diverse structure, subcellular localization, and interactions of the HK proteins, as well as their signaling functions during development and environmental responses across different plant species. Based on data collected from scientific studies, knowledge about acting mechanisms and regulatory roles of HK proteins is presented. This comprehensive summary ofthe HK-related network provides a panorama of sophisticated modulating activities of HK members and gaps in understanding these activities, as well as the basis for developing biotechnological strategies to enhance the quality of crop plants.

Protein Phosphatase Type 2C Functions in Phytohormone-Dependent Pathways and in Plant Responses to Abiotic Stresses.

Plants, as sessile organisms, are susceptible to a myriad of stress factors, especially abiotic stresses. Over the course of evolution, they have developed multiple mechanisms to sense and transduce environmental stimuli for appropriate responses. Among those, phosphorylation and dephosphorylation, regulated by protein kinases and protein phosphatases, respectively, are considered crucial signal transduction mechanisms. Regarding the latter group, protein phosphatases type 2C (PP2Cs) represent the largest division of PPs. In addition, the discovery of regulatory functions of PP2Cs in the abscisic acid (ABA)-signaling pathway, the major signal transduction pathway in abiotic stress responses, indicates the significant importance of PP2C members in plant adaptation to adverse environmental factors. In this review, current understanding of the roles of PP2Cs in different phytohormone-dependent pathways related to abiotic stress is summarized, highlighting the crosstalk between the ABA-signaling pathway with other hormonal pathways via certain ABA-related PP2Cs. We also updated the progress of in planta characterization studies of PP2Cs under abiotic stress conditions, providing knowledge of PP2C manipulation in developing abiotic stress-tolerant crops.

Ectopic expression of GmHP08 enhances resistance of transgenic Arabidopsis toward drought stress.

KEY MESSAGE: Ectopic expression of Glycine max two-component system member GmHP08 in Arabidopsis enhanced drought tolerance of transgenic plants, possibly via ABA-dependent pathways. Phosphorelay by two-component system (TCS) is a signal transduction mechanism which has been evolutionarily conserved in both prokaryotic and eukaryotic organisms. Previous studies have provided lines of evidence on the involvement of TCS genes in plant perception and responses to environmental stimuli. In this research, drought-associated functions of GmHP08, a TCS member from soybean (Glycine max L.), were investigated via its ectopic expression in Arabidopsis system. Results from the drought survival assay showed that GmHP08-transgenic plants exhibited higher survival rates compared with their wild-type (WT) counterparts, indicating better drought resistance of the former group. Analyses revealed that the transgenic plants outperformed the WT in various regards, i.e. capability of water retention, prevention of hydrogen peroxide accumulation and enhancement of antioxidant enzymatic activities under water-deficit conditions. Additionally, the expression of stress-marker genes, especially antioxidant enzyme-encoding genes, in the transgenic plants were found greater than that of the WT plants. In contrary, the expression of SAG13 gene, one of the senescence-associated genes, and of several abscisic acid (ABA)-related genes was repressed. Data from this study also revealed that the ectopic expression lines at germination and early seedling development stages were hypersensitive to exogenous ABA treatment. Taken together, our results demonstrated that GmHP08 could play an important role in mediating plant response to drought, possibly via an ABA-dependent manner.

Chemical constituents of Vietnamese mangrove Hibiscus tiliaceus with antioxidant and alpha-glucosidase inhibitory activity.

Using various chromatographic techniques, a total of 15 compounds, including one novel megastigmane named tiliaceic acid A (1) and 14 known compounds, were isolated from the traditional medicinal Vietnamese mangrove Hibiscus tiliaceus. Their structures were confirmed based on spectroscopic experiments including, UV, 1 D- and 2 D-NMR, HR-ESI-MS, and ECD analysis. The antioxidant and α-glucosidase inhibitory activities of the isolated compounds from H. tiliaceus were evaluated for the first time. Compound 2 showed strong α-glucosidase inhibitory activity with an IC50 of 77.78 ± 1.00 µM compared with the positive control acarbose at 105.71 ± 2.29 µM.

Heterologous Expression of a Soybean Gene RR34 Conferred Improved Drought Resistance of Transgenic Arabidopsis.

Two-component systems (TCSs) have been identified as participants in mediating plant response to water deficit. Nevertheless, insights of their contribution to plant drought responses and associated regulatory mechanisms remain limited. Herein, a soybean response regulator (RR) gene RR34, which is the potential drought-responsive downstream member of a TCS, was ectopically expressed in the model plant Arabidopsis for the analysis of its biological roles in drought stress response. Results from the survival test revealed outstanding recovery ratios of 52%-53% in the examined transgenic lines compared with 28% of the wild-type plants. Additionally, remarkedly lower water loss rates in detached leaves as well as enhanced antioxidant enzyme activities of catalase and superoxide dismutase were observed in the transgenic group. Further transcriptional analysis of a subset of drought-responsive genes demonstrated higher expression in GmRR34-transgenic plants upon exposure to drought, including abscisic acid (ABA)-related genes NCED3, OST1, ABI5, and RAB18. These ectopic expression lines also displayed hypersensitivity to ABA treatment at germination and post-germination stages. Collectively, these findings indicated the ABA-associated mode of action of GmRR34 in conferring better plant performance under the adverse drought conditions.

Role and Regulation of Cytokinins in Plant Response to Drought Stress.

Cytokinins (CKs) are key phytohormones that not only regulate plant growth and development but also mediate plant tolerance to drought stress. Recent advances in genome-wide association studies coupled with in planta characterization have opened new avenues to investigate the drought-responsive expression of CK metabolic and signaling genes, as well as their functions in plant adaptation to drought. Under water deficit, CK signaling has evolved as an inter-cellular communication network which is essential to crosstalk with other types of phytohormones and their regulating pathways in mediating plant stress response. In this review, we revise the current understanding of CK involvement in drought stress tolerance. Particularly, a genetic framework for CK signaling and CK crosstalk with abscisic acid (ABA) in the precise monitoring of drought responses is proposed. In addition, the potential of endogenous CK alteration in crops towards developing drought-tolerant crops is also discussed.

Protective Effects of Compounds from Cimicifuga dahurica against Amyloid Beta Production in Vitro and Scopolamine-Induced Memory Impairment in Vivo.

Cimicifuga dahurica has traditionally been used as an antipyretic, analgesic, and anti-inflammatory agent and as a treatment for uterine and anal prolapse. This study has investigated the potential beneficial effects of this medicinal plant and its components on Alzheimer's disease (AD) with a focus on amyloid beta (Aß) production and scopolamine-induced memory impairment in mice. An ethanol extract from C. dahurica roots decreased Aß production in APP-CHO cells [Chinese hamster ovarian (CHO) cells stably expressing amyloid precursor protein (APP)], as determined by an enzyme-linked immunosorbent assay and Western blot analysis. Then, the compounds isolated from C. dahurica were tested for their antiamyloidogenic activities. Four compounds (1-4) efficiently interrupted Aß generation by suppressing the level of ß-secretase in APP-CHO cells. Moreover, the in vivo experimental results demonstrated that compound 4 improved the cognitive performances of mice with scopolamine-induced disruption on behavioral tests and the expression of memory-related proteins. Taken together, these results suggest that C. dahurica and its constituents are potential agents for preventing or alleviating the symptoms of AD.

Dendrodoristerol, a cytotoxic C20 steroid from the Vietnamese nudibranch mollusk Dendrodoris fumata.

Using various chromatographic separations, four steroids including one new C20 steroid namely dendrodoristerol (1), were isolated from the Vietnamese nudibranch mollusk Dendrodoris fumata. The structure elucidation was confirmed by combination of spectroscopic experiments including 1D and 2D NMR, HR QTOF MS, and CD. Compound 1 was found to exhibit significant in vitro cytotoxic activity against six human cancer cell lines as HL-60, KB, LU-1, MCF-7, LNCaP, and HepG2. In addition, 1 induced HL-60 cancer cell death by apoptosis and necrosis.

A new [7.7]paracyclophane from Vietnamese marine snail Planaxis sulcatus (Born, 1780).

A new [7.7]paracyclophane (1), together with eight known compounds (2-9), were isolated from a MeOH extract of the sea snail Planaxis sulcatus (Born, 1780). Their structures were elucidated by HR-ESI-MS and NMR techniques as well as comparison with those reported in literatures. The absolute configuration of metabolite 1 was determined using ECD spectroscopy. Among nine compounds, 1 exhibited significant cytotoxicity toward all eight cancer cells tested with IC50 values between 1.81 and 3.80 µg/mL.[Figure: see text].

Acylated flavonoid glycosides from Barringtonia racemosa.

Using various chromatographic separations, three new acylated flavonoid glycosides, namely barringosides G-I (1-3), were isolated from the water-soluble extract of Barringtonia racemosa branches and leaves. The structure elucidation was performed by extensive analysis of the 1D and 2D NMR and HR-QTOF-MS data. Of the isolated compounds, barringoside I (3) showed moderate inhibitory effects on LPS-induced NO production in RAW264.7 cells with an IC50 of 52.48 ± 1.04 µM.

Ectopic Expression of Glycine maxGmNAC109 Enhances Drought Tolerance and ABA Sensitivity in Arabidopsis.

The NAC (NAM, ATAF1/2, CUC2) transcription factors are widely known for their various functions in plant development and stress tolerance. Previous studies have demonstrated that genetic engineering can be applied to enhance drought tolerance via overexpression/ectopic expression of NAC genes. In the present study, the dehydration- and drought-inducible GmNAC109 from Glycine max was ectopically expressed in Arabidopsis (GmNAC109-EX) plants to study its biological functions in mediating plant adaptation to water deficit conditions. Results revealed an improved drought tolerance in the transgenic plants, which displayed greater recovery rates by 20% to 54% than did the wild-type plants. In support of this finding, GmNAC109-EX plants exhibited lower water loss rates and decreased endogenous hydrogen peroxide production in leaf tissues under drought, as well as higher sensitivity to exogenous abscisic acid (ABA) treatment at germination and early seedling development stages. In addition, analyses of antioxidant enzymes indicated that GmNAC109-EX plants possessed stronger activities of superoxide dismutase and catalase under drought stress. These results together demonstrated that GmNAC109 acts as a positive transcriptional regulator in the ABA-signaling pathway, enabling plants to cope with adverse water deficit conditions.