High-Throughput Experimentation and Machine Learning-Assisted Optimization of Iridium-Catalyzed Cross-Dimerization of Sulfoxonium Ylides.

A novel and convenient approach that combines high-throughput experimentation (HTE) with machine learning (ML) technologies to achieve the first selective cross-dimerization of sulfoxonium ylides via iridium catalysis is presented. A variety of valuable amide-, ketone-, ester-, and N-heterocycle-substituted unsymmetrical E-alkenes are synthesized in good yields with high stereoselectivities. This mild method avoids the use of diazo compounds and is characterized by simple operation, high step-economy, and excellent chemoselectivity and functional group compatibility. The combined experimental and computational studies identify an amide-sulfoxonium ylide as a carbene precursor. Furthermore, a comprehensive exploration of the reaction space is also performed (600 reactions) and a machine learning model for reaction yield prediction has been constructed.

Enhanced formaldehyde oxidation over MnO2 and doped manganese-based catalysts: Experimental and theoretical Insights into mechanism and performance.

Thermal catalytic degradation of formaldehyde (HCHO) over manganese-based catalysts is garnering significant attention. In this study, both theoretical simulations and experimental methods were employed to elucidate the primary reaction pathways of HCHO on the MnO2(110) surface. Specifically, the effects of doping MnO2 with elements such as Fe, Ce, Ni, Co, and Cu on the HCHO oxidation properties were evaluated. Advanced characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS), were employed to discern the physical properties and chemical states of the active components on the catalyst surface. The comprehensive oxidation pathway of HCHO on the MnO2(110) surface includes O2 adsorption and dissociation, HCHO adsorption and dehydrogenation, CO2 desorption, H2O formation and desorption, oxygen vacancy supplementation, and other elementary reactions. The pivotal rate-determining step was identified as the hydrogen migration process, characterized by an energy barrier of 234.19 kJ mol-1. Notably, HCHOO and *CHOO emerged as crucial intermediates during the reaction. Among the doped catalysts, Fe-doped MnO2 outperformed its counterparts doped with Ce, Ni, Co, and Cu. The optimal degradation rate and selectivity were achieved at a molar ratio of Fe: Mn = 0.1. The superior performance of the Fe-doped MnO2 can be ascribed to its large specific surface area, conducive pore structure for HCHO molecular transport, rich surface-adsorbed oxygen species, and a significant presence of oxygen vacancies.

Stay Hydrated! Impact of Solvation Phenomena on the CO2 Reduction Reaction at Pb(100) and Ag(100) surfaces.

Herein, a comprehensive computational study of the impact of solvation on the reduction reaction of CO2 to formic acid (HCOOH) and carbon monoxide on Pb(100) and Ag(100) surfaces is presented. Results further the understanding of how solvation phenomena influence the adsorption energies of reaction intermediates. We applied an explicit solvation scheme harnessing a combined density functional theory (DFT)/microkinetic modeling approach for the CO2 reduction reaction. This approach reveals high selectivities for CO formation at Ag and HCOOH formation on Pb, resolving the prior disparity between ab initio calculations and experimental observations. Furthermore, the detailed analysis of adsorption energies of relevant reaction intermediates shows that the total number of hydrogen bonds formed by HCOO plays a primary role for the adsorption strength of intermediates and the electrocatalytic activity. Results emphasize the importance of explicit solvation for adsorption and electrochemical reaction phenomena on metal surfaces.

pH Effects in a Model Electrocatalytic Reaction Disentangled.

Varying the solution pH not only changes the reactant concentrations in bulk solution but also the local reaction environment (LRE) that is shaped furthermore by macroscopic mass transport and microscopic electric double layer (EDL) effects. Understanding ubiquitous pH effects in electrocatalysis requires disentangling these interwoven factors, which is a difficult, if not impossible, task without physical modeling. Herein, we demonstrate how a hierarchical model that integrates microkinetics, double-layer charging, and macroscopic mass transport can help understand pH effects of the formic acid oxidation reaction (FAOR). In terms of the relation between the peak activity and the solution pH, intrinsic pH effects without consideration of changes in the LRE would lead to a bell-shaped curve with a peak at pH = 6. Adding only macroscopic mass transport, we can already reproduce qualitatively the experimentally observed trapezoidal shape with a plateau between pH 5 and 10 in perchlorate and sulfate solutions. A quantitative agreement with experimental data requires consideration of EDL effects beyond Frumkin correlations. Specifically, the peculiar nonmonotonic surface charging relation affects the free energies of adsorbed intermediates. We further discuss pH effects of FAOR in phosphate and chloride-containing solutions, for which anion adsorption becomes important. This study underpins the importance of a full consideration of multiple interrelated factors for the interpretation of pH effects in electrocatalysis.

Influence mechanism of plant litter mediated reduction of iron and sulfur on migration of potentially toxic elements from mercury-thallium mine waste.

The decomposition of plant litter in soil changes soil nutrient content and plays an important role in regulating soil pH and availability of potentially toxic elements (PTEs). However, there remains limited studies on the mechanism under which litter influences the transport of PTEs in the process of ecological restoration. This study examined the effect of plant litter decomposition mediated reduction of iron and sulfur components on migration of PTEs from mercury-thallium mine waste. The results showed that the four kinds of litter alleviated the acidity of the waste, especially the Bpa and Tre litter. The nitro and nitroso groups produced by the decomposition of the litter were adsorbed onto the waste, thereby providing an electron transfer medium for iron reducing microorganisms, such as Geobacter. This promoted the reduction and release of Fe3+ to Fe2+ and reduced the electronegativity (El) value of waste. The reduced El promoted the adsorption of metal cations such as Hg and Tl to maintain electrical neutrality. However, it was not conducive to the adsorption of oxygen containing anions of As and Sb. An increase in litter resulted in an increase in reductivity of mercury-thallium mine waste. This maintained the reduction of Fe3+ to Fe2+ and changed or destroyed the structure of silicate minerals. PTEs, such as Tl, Hg, As, and Sb, were released, resulting in reductions in their residual fraction. However, the strong reduction conditions, especially the decomposition of Bpa, caused part of the released Hg(II) combining with S2- produced by the reduction of SO42- to form insoluble HgS, thereby reducing its migration. The findings could provide a theoretical basis to guide the situ-control and ecological restoration of PTEs in waste slag site.

Correlation Analysis of the Carboxyl and Carbonyl Groups of Natural Organic Matter and the Formation Potential of Trihalomethanes and Chloral Hydrate.

Natural organic matter (NOM) has always been considered the main precursor of disinfection by-products (DBPs) during the chlorine disinfection of drinking water. This research focuses on investigating the correlation between the functional group (carboxyl and carbonyl groups) content of NOM and the formation of trichloromethane (TCM) and chloral hydrate (CH). The quantitative determination of carboxyl groups, carbonyl groups, TCM, and CH were conducted during the drinking water treatment processes with different coagulant dosages and with/without pre-oxidation by KMnO4 or NaClO. The most appropriate coagulant for the removal of conventional components was polyaluminum chloride (PAC), and the dosage was 110 mg/L. Up to 43.7% and 14.5% of the carboxyl and carbonyl groups, respectively, were removed through the coagulation and sedimentation processes, which can be enhanced by increasing PAC dosage. The filtration process further increased the removal rates of these two functional groups to 59.8% and 33.5%, respectively. The formation potential of the TCM and CH decreased as the PAC dosage increased. Pre-oxidation by KMnO4 (0.8-1.0 mg/L) effectively controlled the formation of DBPs while increasing the carboxyl and carbonyl group content. Pre-oxidation by NaClO decreased the formation of TCM rather than CH, and a suitable amount (0.5-1.0 mg/L) decreased the carboxyl and carbonyl groups. It was found that there was a good linear correlation between carboxyl groups and TCM and CH. The linear fit R2 values of the carboxyl groups to TCM and CH were 0.6644 and 0.7957, respectively. The linear fit R2 values of the carbonyl groups to TCM and CH were 0.5373 and 0.7595, respectively.

Activation of peroxymonosulfate by palygorskite-mediated cobalt-copper-ferrite nanoparticles for bisphenol S degradation: Influencing factors, pathways and toxicity evaluation.

Peroxymonosulfate (PMS)-based advanced oxidation process is considered a potential technology for water treatment. Here, palygorskite (PAL)-mediated cobalt-copper-ferrite nanoparticles (16%-CoCu0.4Fe1·6O4@PAL, donated as 16%-CCFO@PAL) were employed for PMS activation to remove bisphenol S (BPS). BPS degradation was greater than 99% under the optimal conditions within 25 min, on which the effects of various influencing factors were explored. The adsorption dissociation energy of PMS over 16%-CCFO@PAL was -6.27 eV, which was lower than that of the Cu-free catalyst (-6.15 eV), demonstrating the excellent catalytic ability of 16%-CCFO@PAL. The efficient catalytic ability of 16%-CCFO@PAL was also verified in real water samples. The oxidation intermediates were identified and their generations were systematically analyzed by DFT calculations. The possible degradation pathways of BPS were proposed and the toxicity of products was predicted. BPS affected the normal development of zebrafish embryos and the levels of sex hormone in adult male zebrafish, and was harmful to the tissues, such as testis, liver, and intestine of zebrafish. The 16%-CCFO@PAL/PMS process can effectively reduce the toxicity of BPS-polluted water. This study paves the way for the real application of 16%-CCFO@PAL/PMS oxidation process and provides a new perspective for the evaluation of water toxicity.

Molten salt-induced vertical CoP/Co nanosheets array coupled with carbon for efficient water splitting.

The exploration of high-efficiency non-noble metal catalysts for improving the intrinsic activity and active sites for overall water splitting persists as a bottleneck issue. Herein, a facile heterogeneous molten salt strategy has been proposed to fabricate CoP/Co nanosheets array that is vertically attached to a carbon matrix. Such a hierarchical structure endows the hybrid with abundant active sites and favorable reaction kinetics. Experimental results reveal that the molten salt determines the final shape of metallic Co, which is not sensitive to the organic sources. After optimization of the molten salt mass, the CoP/Co/C-6 shows the best bifunctional performance, requiring an overpotential of 132 mV and 320 mV at 10 mA cm-2 for hydrogen evolution reaction and oxygen evolution reaction, respectively. Theoretical simulation results manifest the CoP/Co heterostructure alters the electronic structure of Co and CoP, and reduces the adsorption free energy of intermediates, thus further boosting the electrocatalysis activity. This work proposes a molten salt-assisted method for the rational design of novel two-dimensional nano-hybrids for energy conversion applications.

Preparation of novel N-doped biochar and its high adsorption capacity for atrazine based on π-π electron donor-acceptor interaction.

Novel nitrogen (N)-doped cellulose biochar (NC1000-10) with large adsorption capacity (103.59 mg g-1) for atrazine (ATZ) was synthesized through the one-pot method. It has the best adsorption efficiency than N-doped biochars prepared from hemicellulose and lignin. The adsorption behaviors of ATZ by N-doped biochars with different N doping ratios (NC1000-5, NC1000-10, NC1000-20 and NC1000-30) were significantly different, which was attributed to the difference of sp2 conjugate C (ID/IG = 0.99-1.18) and doped heteroatom N (pyridinic N, pyrrolic N and graphitic N). Adsorption performance of ATZ on NC1000-10 conformed to the pseudo-second-order kinetic and Langmuir adsorption isotherm model. Thermodynamic calculations showed that adsorption performance was favorable. Besides, wide pH adaptability (pH = 2-10), good resistance to ionic strength and excellent recycling efficiency make it have extensive practical application potential. Further material characterizations and the density functional theory (DFT) calculations indicated that good adsorption performance of NC1000-10 for ATZ mainly depended on chemisorption, and π-π electron donor-acceptor (EDA) interaction contributed the most due to high graphitization degree. Specifically, pyridinic N and graphitic N further promoted adsorption performance by hydrophobic effect and π-π EDA interaction between ATZ and NC1000-10, respectively. Pyrrolic N and other surface functional groups (-COOH, -OH) facilitated the hydrogen bond effect.

Rapid Gelling of Guar Gum Hydrogel Stabilized by Copper Hydroxide Nanoclusters for Efficient Removal of Heavy Metal and Supercapacitors.

In this paper, guar gum (GG) hydrogel has been successfully prepared by adding GG and Cu2+ mixture into an alkaline medium. The formation mechanism of the hydrogel has been investigated through various techniques. Results reveal GG facilitates the formation of ultrafine copper hydroxide clusters with a diameter of ∼3 nm. Moreover, these nanoclusters bring about a rapid gelling of GG within 10 ms. The synthesized hydrogel is applied to the adsorption of heavy metal ions from wastewater. The hydrogel shows excellent removal efficiency in removing various heavy metal ions. Besides, the hydrogel derived porous carbon exhibits high specific capacitance (281 F/g at 1 A/g) and excellent rate capacity. The high contaminant removal efficiency character and excellent electrochemical performance endow GG hydrogel with potential applications in the environmental and energy storage field.

Perioperative analgesia with ultrasound-guided quadratus lumborum block for transurethral resection of prostate.

BACKGROUND: Prostatic hyperplasia is a physiological aging process in men. After transurethral resection of prostate (TURP), visceral pain is the main cause. The effective postoperative analgesia can reduce the occurrence of postoperative complications. This study mainly studied the analgesic effect of quadratus lumborum block (QLB) on TURP. METHODS: We divided 62 patients undergoing TURP into 2 groups using a random number table method (QLB 2 group and non-QLB [control] group). Patients in the QLB group underwent ultrasound-guided posterior QLB with 20 mL of 0.25% ropivacaine on each side, and those in the control group received only general anesthesia. The primary outcome for this study was the consumption analgesic pump during 0 to 24 hours. The secondary outcomes included the first pressing time of analgesic pump during 0 to 24 hours, the pain at rest and when coughing at 1, 4, 8, 12, and 24 hours post-operation as measured with a visual analogue scale for pain, length of the hospital stay, and complications (nausea and vomiting, dizziness, and abdominal distension). RESULTS: Patients in the QLB group presented less consumption, later first pressing time of analgesic pump during 0 to 24 hours after surgery lower visual analogue scale scores at 1, 4, 8, 12, and 24 hours postsurgery than those in the control group. Moreover, their mean length of hospital stay was shorter (P = .023), and they experienced less postoperative complications than the patients in the control group. CONCLUSIONS: Ultrasound-guided QLB in TURP provided a significant analgesic effect in our patients the first day after surgery. This analgesic model may improve the postoperative recovery after TURP.

Improvement of the fabricated and application of aluminosilicate-based microfiltration membrane.

Aluminosilicate composite materials are characterized by their low cost, nontoxicity and facilely shaped. Membrane prepared using aluminosilicate composites have the following disadvantages: large mean pore size and low mechanical strength. To address these limitations, flat microfiltration membranes were fabricated using SiO2 powder and aluminosilicate composite as raw materials. The membrane performance was optimized by regulating the particle size of SiO2, the ratio of SiO2 to aluminosilicate composite (s/a), and the type of chemical admixture. The X-ray diffraction results indicated that the crystalline SiO2 particles were favorable for the preparation of membranes with higher bending strengths. The decreasing particle sizes of SiO2 (1.33-0.15 µm) decreased the pore size distribution. The bending strength of the membrane reduced with an increase in s/a, while was effectively enhanced by adding dissolved Na2SiO3. The optimized inorganic microfiltration membrane could also catalyze ozone to remove 100% of benzophenone-4 with an initial concentration of 10 mg L-1 within 15 min, and TOC removal by 52.67%. This paper presents a revised method for preparing an inorganic microfiltration membrane, which is an increasingly promising material for water treatment because of its low cost, low energy consumption, and high catalytic performance.

Knockdown of Nav1.5 inhibits cell proliferation, migration and invasion via Wnt/ß-catenin signaling pathway in oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is a common type of malignant oral cancer that has a high recurrence rate. Voltage-gated sodium channel Nav1.5 was reported to be highly up-regulated in various types of cancers. However, the regulatory mechanism of Nav1.5 in cancers including OSCC still remains elusive. In this study, Nav1.5 was found to be highly expressed in OSCC tissues and cells. Through the analysis of clinical characteristics of patients, we found that the expression level of Nav1.5 was closely related to neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, tumor-node-metastasis stage, and lymph node metastasis. Moreover, we found that Nav1.5 mainly located on the cell membrane as well as cytoplasm and knockdown of Nav1.5 promoted cell apoptosis and decreased proliferation in OSCC. Transwell assay results showed that knockdown of Nav1.5 effectively suppressed the migration and invasion in OSCC. In addition, knockdown of Nav1.5 was found to inhibit the protein and mRNA expression levels of ß-catenin, cyclin D1, and c-Myc in the Wnt/ß-catenin signaling pathway. In summary, these results indicated that Nav1.5 may be involved in the progression of OSCC through the Wnt/ß-catenin signaling pathway.

TVT-O vs TVT-S for female stress urinary incontinence: A systematic review and meta-analysis.

BACKGROUND: Tension-free vaginal tape obturator (TVT-O) and tension-free vaginal tape secur (TVT-S) are common surgeries for the treatment of stress urinary incontinence (SUI), several randomised controlled trials (RCTs) have compared the effects of TVT-O and TVT-S, yet the results remained inconsistent. Therefore, we attempted to conduct this systematic review and meta-analysis to analyse the role of TVT-O and TVT-S in patients with SUI. METHODS: We searched PubMed databases from inception date to Jan 15, 2020 for RCTs that compared TVT-O and TVT-S in SUI patients. Two authors independently screened and extracted data from the published articles. Summary odd ratios (OR) or mean differences (MD) with 95% confidence intervals (95% CI) were calculated for each outcome by fixed- or random-effects model. RESULTS: Seven RCTs with a total of 755 patients were identified, with 373 patients for TVT-O and 382 patients for TVT-S. TVT-O preceded TVT-S in the objective cure at 12 months (OR = 1.72, 95% CI 1.21-2.45), subjective cure (OR = 1.98, 95% CI 1.08-3.62); but TVT-S have more advantage in the incidence of postoperative thigh pain (OR = 18.94, 95% CI 7.01-51.15); no significant differences on the duration of operative procedure (OR = -1.09, 95% CI -2.37-0.18), urinary retention (OR = 0.77, 95% CI 0.36-1.62) and urinary infection (OR = 1.80, 95% CI 0.63-5.13) were found. CONCLUSIONS: TVT-O should be preferred for patients with SUI even though with higher risks of postoperative thigh pain when compared with TVT-S, more related studies are needed to identify the role of TVT-O and TVT-S for the treatment of SUI.

Functional Pathway Between Cervical Spinal and Sympathetic Ganglia: A Neurochemical Foundation Between Neck Pain and Vertigo.

BACKGROUND: Cervical vertigo commonly concurs in patients with neck pain, but the concurrent mechanism of these 2 symptoms still remains unclear. We previously reported a bidirectional segmental nerve fiber connection between cervical spinal and sympathetic ganglia, which provided a hypothesis that this connection between the 2 ganglia may be the anatomic basis for the concurrence of neck pain and cervical vertigo. However, this concurrent mechanism needs biochemical and functional evidence. OBJECTIVES: This study aimed to investigate a possible noradrenergic pathway between cervical spinal and sympathetic ganglia. STUDY DESIGN: We performed both clinical and laboratory research. Clinical observation was a prospective case-control study. SETTING: Clinical study took place in our hospital; laboratory study was in an orthopedic laboratory. METHODS: Cervical lamina block therapy used in patients with cervical vertigo was clinically evaluated; norepinephrine (NE) expressions in cervical sympathetic ganglia were analyzed using immunohistochemical staining after electrical stimulation to the cervical spinal ganglia; the influence of phentolamine local injection to the vertebrobasilar artery flow was experimentally measured. RESULTS: Cervical lamina block therapy could significantly shorten the clinical hospital stays of patients with cervical vertigo (P = 0.000) and improve vertebral artery flow (P < 0.05). NE expressions in superior cervical sympathetic ganglia (SCG) or inferior cervical sympathetic ganglia (ICG) increased significantly when ipsilateral C2 to C3 or C6 to C8 spinal ganglia were electrically stimulated, respectively. Adrenergic receptor block with phentolamine significantly inhibited the decrease of basilar artery (BA) flow induced by electrical stimulation of the cervical spinal ganglia. The change range of BA flow caused by stimulations of C2 to C3 and C6 to C8 spinal ganglia was more than that of C4 and C5. LIMITATIONS: The inpatients observed in this clinical study might be influenced by some factors including emotion, diet, sleep, and others. The limitations of the laboratory study included animal species and small sample size. CONCLUSIONS: Adrenergic system could play a part in cervical spinal ganglia altering the vertebrobasilar artery system. It could provide a neurochemical foundation between neck pain and vertigo, and that segmental functional connections exist between cervical spinal and sympathetic ganglia. KEY WORDS: Cervical vertigo, neck pain, cervical sympathetic ganglia, cervical spinal ganglia, noradrenaline.

Soil and vegetation conditions changes following the different sand dune restoration measures on the Zoige Plateau.

Alpine sand dunes restoration is extremely difficult but important in the ecosystem restoration. Sand dunes are known as harsh soil and poor seed bank which freed from advantages on plants growth naturally. Effective restoration measures are required to guide the sand dune restoration. Here, indigenous grass (Elymus nutans) was sown in sand dune on the Zoige Plateau and treated with no sand barrier (CK) and environmental friendly materials including wicker sand barrier (wicker) and sandbag sand barrier (sandbag). The soil conditions were assessed by measuring the soil moisture and nutrients of the topsoil, and interspecific relationship and population niche were utilized to analyze the plant community structure variances among different restoration measures. Results showed that the soil and vegetation in the sand barriers measures were better than that in the CK. The soil moisture in the sandbag measure was 16.67% higher than that in the wicker measure. The nutrients content and microbial biomass were also the best in the sandbag measures. The ratio of strong association was the highest in the sandbag measure and the lowest in the CK, whereas the plants had the highest none association ratio in the CK. In addition, the average population niche overlap ranked by sandbag (0.39)>wicker (0.32)>CK (0.26). Thus, incorporation of sand barriers and indigenous grass seeding in alpine sand dunes could promote the sand dune restoration. And the sandbag measure showed a stronger improvement effect on the sand dune soil and vegetation conditions than the wicker measure.

Long non-coding RNAs in Oral squamous cell carcinoma: biologic function, mechanisms and clinical implications.

There is growing evidence that regions of the genome that cannot encode proteins play an important role in diseases. These regions are usually transcribed into long non-coding RNAs (lncRNAs). LncRNAs, little or no coding potential, are defined as capped transcripts longer than 200 nucleotides. New sequencing technologies have shown that a large number of aberrantly expressed lncRNAs are associated with multiple cancer types and indicated they have emerged as an important class of pervasive genes during the development and progression of cancer. However, the underlying mechanism in cancer is still unknown. Therefore, it is necessary to elucidate the lncRNA function. Notably, many lncRNAs dysregulation are associated with Oral squamous cell carcinoma (OSCC) and affect various aspects of cellular homeostasis, including proliferation, survival, migration or genomic stability. This review expounds the up- or down-regulation of lncRNAs in OSCC and the molecular mechanisms by which lncRNAs perform their function in the malignant cell. Finally, the potential of lncRNAs as non-invasive biomarkers for OSCC diagnosis are also described. LncRNAs hold promise as prospective novel therapeutic targets, but more research is needed to gain a better understanding of their biologic function.

Impact of plateau pikas (Ochotona curzoniae) on soil properties and nitrous oxide fluxes on the Qinghai-Tibetan Plateau.

This paper demonstrates the impact of an endemic fossorial animal, plateau pika (Ochotona curzoniae), on soil properties and N2O flux at the Zoige Wetland. Pika burrow and control sites without disturbance by pika were selected to measure the soil water content, bulk density, soil organic matter (SOM), NH4-N content and NO3-N content in August 2012. N2O fluxes were measured with static opaque chambers at these sites in June and August 2012. Pika burrowing altered soil aeration by transferring deeper soil to the surface and by constructing underground burrows, which significantly increased bulk density, and reduced soil water content, SOM and NH4-N content at 0-10 cm and 10-20 cm soil depth. N2O flux had a significant correlation with bulk density, SOM and NH4-N content. Pika burrowing significantly influenced N2O flux by increasing N2O flux at the control site from near zero to 0.063±0.011 mg m-2 h-1. Our findings described how pika burrowing influences the soil traits and significantly increases the principal greenhouse gas N2O emission. As plateau pika was commonly considered as a pest, our findings give a novel clue to effectively manage populations of plateau pika on the Qinghai-Tibet Plateau from the perspective of greenhouse gas emission.

Fusarihexins A and B: Novel Cyclic Hexadepsipeptides from the Mangrove Endophytic Fungus Fusarium sp. R5 with Antifungal Activities.

Two novel cyclic hexadepsipeptides, fusarihexin A (1: ) and fusarihexin B (2: ), and two known compounds, cyclo-(L-Leu-L-Leu-D-Leu-L-Leu-L-Val) (3: ) and cyclo-(L-Leu-L-Leu-D-Leu-L-Leu-L-Ile) (4: ), were isolated from the marine mangrove endophytic fungus Fusarium sp. R5. Their chemical structures were elucidated on the basis of spectroscopic data and Marfey's analysis. In an in vitro bioassay, fusarihexin A (1: ) remarkably inhibited three plant pathogenic fungi: Colletotrichum gloeosporioides (Penz.) Sacc., which causes anthracnose in many fruits and vegetables, Colletotrichum musae (Berk. and M. A. Curtis) Arx, which causes crown rot and anthracnose in bananas, and Fusarium oxysporum Schlecht. f. sp. lycopersici (Sacc.) W. C. Snyder et H. N. Hansen, which causes Fusarium wilt and fruit rot in tomatoes. Fusarihexin B (2: ) strongly inhibited C. gloeosporioides and C. musae. The compounds were more potent than carbendazim, which is widely used as an agricultural and horticultural fungicide worldwide.