Enantioselectivity and allelopathy both have effects on the inhibition of napropamide on Echinochloa crus-galli

Napropamide is a chiral acetamide herbicide commonly applied to control Echinochloa crus-galli in maize. The inhibition effect may be enantioselective for Echinochloa crus-galli and maize. It may also be affected by the potential allelopathy at field condition. To investigate this, we have examined the inhibition effect of napropamide on Echinochloa crus-galli mono-cultured or co-cultured with maize at field conditions. Our results on morphology, physiology, chlorophyll content and chlorophyll fluorescence suggest that R-napropamide has stronger inhibitory effect than Rac-napropamide and S-napropamide on Echinochloa crus-galli, while none of them affects maize. We found that both glutathione-S-transferase (GST) genes and oxidative enzymes (superoxide dismutase, malondialdehyde) played roles in the inhibition. Accumulations of napropamide in Echinochloa crus-galli were more prominent in roots than in shoots, and no enantioselectivity was found in medium dissipation. We have observed relative allelopathy when applying napropamide to Echinochloa crus-galli co-cultured with maize. The results warrant further field studies on the enantioselectivity and allelopathy of herbicides

Deviations from Beer's law in electronic absorption and circular dichroism: Detection for enantiomeric excess analysis

The electronic absorption (UV) to circular dichroism (CD) signal ratio can be used for enantiomeric excess (ee) analysis within linear range. However, CD detection often requires a high sample concentration where deviations from Beer's law may occur. Individual enantiomers of four chiral compounds were separated from commercial racemates by semipreparative high‐performance liquid chromatography (HPLC) with chiral columns. They were used to trace possible deviations in both UV and CD detection on achiral HPLC with a photodiode array detector and a CD detector. The CD/UV ratios for samples with the same ee value decreased by up to 7.8 to 52% when the injection volume increased, indicating that the linear standard curve of ee versus CD/UV is only valid within a narrow range. To extend the sample amount to a wider range, a data‐processing method was developed based on two second‐order polynomial functions, which were constructed to fit the relationship between the intensities of the UV and CD signals for two enantiomers. Moreover, a more simplified method based on a third‐order polynomial function was established to calculate the ee values. The variations between the predicted and experimental ee values were within ±0.08 for both methods. To our knowledge, this is the first study that the deviations from Beer's law are considered in both UV and CD detection for ee analysis

Enantioselectivity and allelopathy both have effects on the inhibition of napropamide on Echinochloa crus-galli

Napropamide is a chiral acetamide herbicide commonly applied to control Echinochloa crus-galli in maize. The inhibition effect may be enantioselective for Echinochloa crus-galli and maize. It may also be affected by the potential allelopathy at field condition. To investigate this, we have examined the inhibition effect of napropamide on Echinochloa crus-galli mono-cultured or co-cultured with maize at field conditions. Our results on morphology, physiology, chlorophyll content and chlorophyll fluorescence suggest that R-napropamide has stronger inhibitory effect than Rac-napropamide and S-napropamide on Echinochloa crus-galli, while none of them affects maize. We found that both glutathione-S-transferase (GST) genes and oxidative enzymes (superoxide dismutase, malondialdehyde) played roles in the inhibition. Accumulations of napropamide in Echinochloa crus-galli were more prominent in roots than in shoots, and no enantioselectivity was found in medium dissipation. We have observed relative allelopathy when applying napropamide to Echinochloa crus-galli co-cultured with maize. The results warrant further field studies on the enantioselectivity and allelopathy of herbicides

Enantiomeric environmental behavior, oxidative stress and toxin release of harmful cyanobacteria Microcystis aeruginosa in response to napropamide and acetochlor

Harmful algal blooms have emerged as a worldwide issue. After concentrations of herbicides entering water, herbicides in water may pose ecological effects on them. The present study investigates the toxicity and environmental behavior of the herbicides, napropamide and acetochlor as enantiomers and as racemates on Microcystis aeruginosa which is the main specie known to produce hepatotoxins. S-napropamide/acetochlor are degraded faster than their corresponding isomer R-napropamide/acetochlor, with the latter more prone to accumulate in algal cells. Moreover, all the enantiomers did not undergo measurable racemization in the medium and algal cells. S-napropamide/acetochlor exhibited much higher toxicity than R-napropamide/acetochlor, with the S-enantiomer inducing a much greater production of antioxidant defense enzymes (superoxide dismutase (SOD) and malondialdehyde (MDA)) and microcystins (MC). SOD and MC increased after treatment with the herbicides and these increases were dependent on the exposure time, whereas MDA showed no apparent change. The information provided in this work will be useful for understanding the toxicity mechanism and environmental behaviors of different amide herbicides (napropamide and acetochlor) in aquatic environments at the enantiomeric level. Additionally, analysis of chiral herbicides in aquatic system needs more attention to aide in the environmental assessment of chiral herbicides

Enantioseparation of napropamide by supercritical fluid chromatography: Effects of the chromatographic conditions and separation mechanism

Supercritical fluid chromatography (SFC) is already used for enantioseparation in the pharmaceutical industry, but it is rarely used for the separation of chiral pesticides. Comparing with high performence liquid chromatography, SFC uses much more environmnetal friendly and economic mobile phase, supercritical CO2. In our work, the enantioseparation of an amide herbicide, napropamide, using three different polysaccharide‐type chiral stationary phases (CSPs) in SFC was investigated. By studying the effect of different CSPs, organic modifiers, temperature, back‐pressure regulator pressures, and flow rates for the enantioseparation of napropamide, we established a rapid and green method for enantioseparation that takes less than 2 minutes: The column was CEL2, the mobile phase was CO2 with 20% 2‐propanol, and the flow rate was 2.0 mL/min. We found that CEL2 demonstrated the strongest resolution capability. Acetonitrile was favored over alcoholic solvents when the CSP was amylose and 2‐propanol was the best choice when using cellulose. When the concentration of the modifiers or the flow rate was decreased, resolutions and analysis times increased concurrently. The temperature and back‐pressure regulator pressure exhibited only minor influences on the resolution and analysis time of the napropamide enantioseparations with these chiral columns. The molecular docking analysis provided a deeper insight into the interactions between the enantiomers and the CSPs at the atomic level and partly explained the reason for the different elution orders using the different chiral columns

Enantioseparation of napropamide by supercritical fluid chromatography: Effects of the chromatographic conditions and separation mechanism

Supercritical fluid chromatography (SFC) is already used for enantioseparation in the pharmaceutical industry, but it is rarely used for the separation of chiral pesticides. Comparing with high performence liquid chromatography, SFC uses much more environmnetal friendly and economic mobile phase, supercritical CO2. In our work, the enantioseparation of an amide herbicide, napropamide, using three different polysaccharide‐type chiral stationary phases (CSPs) in SFC was investigated. By studying the effect of different CSPs, organic modifiers, temperature, back‐pressure regulator pressures, and flow rates for the enantioseparation of napropamide, we established a rapid and green method for enantioseparation that takes less than 2 minutes: The column was CEL2, the mobile phase was CO2 with 20% 2‐propanol, and the flow rate was 2.0 mL/min. We found that CEL2 demonstrated the strongest resolution capability. Acetonitrile was favored over alcoholic solvents when the CSP was amylose and 2‐propanol was the best choice when using cellulose. When the concentration of the modifiers or the flow rate was decreased, resolutions and analysis times increased concurrently. The temperature and back‐pressure regulator pressure exhibited only minor influences on the resolution and analysis time of the napropamide enantioseparations with these chiral columns. The molecular docking analysis provided a deeper insight into the interactions between the enantiomers and the CSPs at the atomic level and partly explained the reason for the different elution orders using the different chiral columns

Table_1_Integrated management improves emerging coastal industries and ecological restoration with the participation of social capital.docx

In this study, we aimed to provide policy advice that supports continuous ecological restoration and coastal economic development. Our analysis indicated that insufficient funds and space are the main problems in mangrove restoration projects in China and Southeast Asian countries. The average cost of mangrove restoration projects in China has been RMB 999,000/ha, leaving a mangrove restoration funding gap of RMB 1,500,000,000/year. Another common problem of emerging industries is insufficient space, another is a lack of subsidies. Learning from the positive experiences of inland areas and Southeast Asian countries, we propose a plan for integrated management that improves emerging marine industries and ecological restoration with the participation of social capital. We also designed a time road map to achieve the plan based on a target area. A SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis showed that the plan is a win-win model plan, which may generally meet the needs of the local government, such as ecological restoration, pollution control, industrial upgrades, and income improvement. Finally, we suggest that governments should strengthen cross-department coordination, improve current sea area use policies, and strengthen associated publicity attempts.</p

Enantiomeric environmental behavior, oxidative stress and toxin release of harmful cyanobacteria Microcystis aeruginosa in response to napropamide and acetochlor

Harmful algal blooms have emerged as a worldwide issue. After concentrations of herbicides entering water, herbicides in water may pose ecological effects on them. The present study investigates the toxicity and environmental behavior of the herbicides, napropamide and acetochlor as enantiomers and as racemates on Microcystis aeruginosa which is the main specie known to produce hepatotoxins. S-napropamide/acetochlor are degraded faster than their corresponding isomer R-napropamide/acetochlor, with the latter more prone to accumulate in algal cells. Moreover, all the enantiomers did not undergo measurable racemization in the medium and algal cells. S-napropamide/acetochlor exhibited much higher toxicity than R-napropamide/acetochlor, with the S-enantiomer inducing a much greater production of antioxidant defense enzymes (superoxide dismutase (SOD) and malondialdehyde (MDA)) and microcystins (MC). SOD and MC increased after treatment with the herbicides and these increases were dependent on the exposure time, whereas MDA showed no apparent change. The information provided in this work will be useful for understanding the toxicity mechanism and environmental behaviors of different amide herbicides (napropamide and acetochlor) in aquatic environments at the enantiomeric level. Additionally, analysis of chiral herbicides in aquatic system needs more attention to aide in the environmental assessment of chiral herbicides

Enantiomeric impacts of two amide chiral herbicides on Echinochloa crus-galli physiology and gene transcription

Echinochloa crus-galli is one of the most noxious weeds in the world and causes yield losses in a variety of different field crops. Napropamide and acetochlor are herbicides commonly employed to control this weed. Both compounds are chiral, with enantiomers displaying different activities. However, it is unclear how the enantiomers of these two chiral herbicides act on different tissues of E. crus-galli. The objective of this paper is to investigate the action mechanism of napropamide and acetochlor in the roots and shoots of E. crus-galli. R‑enantiomers were found to be more active than either the racemates or S-enantiomers on the weed. The content of chlorophyll was not significantly affected by treatment with either enantiomer. The impacts on the activity for the oxidative stress enzymes, except catalase (CAT), showed that both napropamide and acetochlor enantiomers could induce oxidative stress. Furthermore, R‑enantiomers caused greater oxidative damage. Enhanced glutathione-S-transferase (GST) activity and expression of GST genes suggested both EcGSTF1 and EcGSTZ1 were present in the roots and shoots, and this will be helpful for detoxification. The changes in both the roots and shoots revealed the two herbicides displayed tissue selectivity in E. crus-galli. These results enable a better understanding on the mechanism of action for napropamide and acetochlor enantiomers on different tissues, including the shoots and roots in E. crus-galli

Enantiomeric impacts of two amide chiral herbicides on Echinochloa crus-galli physiology and gene transcription

Echinochloa crus-galli is one of the most noxious weeds in the world and causes yield losses in a variety of different field crops. Napropamide and acetochlor are herbicides commonly employed to control this weed. Both compounds are chiral, with enantiomers displaying different activities. However, it is unclear how the enantiomers of these two chiral herbicides act on different tissues of E. crus-galli. The objective of this paper is to investigate the action mechanism of napropamide and acetochlor in the roots and shoots of E. crus-galli. R‑enantiomers were found to be more active than either the racemates or S-enantiomers on the weed. The content of chlorophyll was not significantly affected by treatment with either enantiomer. The impacts on the activity for the oxidative stress enzymes, except catalase (CAT), showed that both napropamide and acetochlor enantiomers could induce oxidative stress. Furthermore, R‑enantiomers caused greater oxidative damage. Enhanced glutathione-S-transferase (GST) activity and expression of GST genes suggested both EcGSTF1 and EcGSTZ1 were present in the roots and shoots, and this will be helpful for detoxification. The changes in both the roots and shoots revealed the two herbicides displayed tissue selectivity in E. crus-galli. These results enable a better understanding on the mechanism of action for napropamide and acetochlor enantiomers on different tissues, including the shoots and roots in E. crus-galli