Syntheses and biological activities of octahydro-1H-cyclopenta[d]pyrimidine derivatives

Various nitromethylene derivatives were synthesized regioselectively. Compounds 8a-f were obtained by the reaction of 1-((5-chloropyridin-2-yl)methyl)-2-(nitromethylene)-octahydro-1H-cyclopenta[d]-pyrimidine (3) with primary amines and formaldehyde. The synthesized compounds were identified by 1H NMR, HRMS (EI), and IR, and preliminary bioassays indicated that most of them showed moderate insecticidal activities against Aphis craccivora. The relationship between hydrophobicity and biological activity was also discussed.     

cis-Configuration: a new tactic/rationale for neonicotinoid molecular design

Resistance development and limited lepidopteran activities call for the discovery of "super-neonicotinoids" solving these problems. Compounds with the cis-configuration offer an opportunity for further optimization. Fixing the nitro group in the cis-configuration provided a new approach for neonicotinoid molecular design. Introductions of the heterocycle or a bulky group are two synthesis concepts to fix the cis-configuration of the nitro group. The design, synthesis, bioactivity, and preliminary modes of action of five types of cis-neonicotinoids are reviewed. cis- and trans-neonicotinoids have some differences in bioactivities and modes of action. This study focused, especially, on the reaction diversities of nitromethylene analogues of imidacloprid with various aldehydes.     

Neonicotinoid insecticides: molecular features conferring selectivity for insect versus mammalian nicotinic receptors

The favorable selective toxicity of neonicotinoid insecticides (represented here by imidacloprid, thiacloprid, and a nitromethylene analogue) for insects versus mammals is not shared by three of their N-unsubstituted imine derivatives or by nicotine or epibatidine. The same selectivity pattern is evident at the receptor level, i.e., the insect nicotinic acetylcholine receptor (nAChR) versus mammalian nAChR subtypes (alpha1, alpha3, alpha4, and alpha7) assayed independently. The insect-selective compounds are not protonated with a nitroimine, cyanoimine, or nitromethylene group and the mammalian-selective compounds are ionized at physiological pH. We propose that the negatively charged tip of the nitro or cyano group (not a partial positive charge at imidazolidine N-1 as suggested earlier) interacts with a putative cationic subsite of the insect nAChR. This contrasts with the mammalian nAChRs where the iminium cation (+C-NH2 <--> C =+NH2) of the neonicotinoid imine derivatives or ammonium nitrogen of nicotine or epibatidine interacts with the anionic subsite.     

Insecticidal and neuroblocking potencies of variants of the imidazolidine moiety of imidacloprid-related neonicotinoids and the relationship to partition coefficient and charge density on the pharmacophore

The pharmacophore of the neonicotinoid insecticide imidacloprid, nitroiminoimidazolidine, was modified to heterocycles such as thiazolidine, pyrrolidine, dihydroimidazole, dihydrothiazole, and pyridone conjugated to nitroimine (=NNO2) or nitromethylene (=CHNO2). Their 6-chloro-3-pyridylmethyl or 5-chloro-3-thiazolylmethyl derivatives were examined for insecticidal activity against the American cockroach by injection and for neuroblocking activity using the cockroach ganglion. Most of the compounds having the neonicotinoidal pharmacophore exhibited insecticidal activity at the nanomolar level, which was enhanced in the presence of synergists, and high neuroblocking activity at the micromolar level. Quantitative analysis for the compounds showed that the neuroblocking potency is proportional both to the Mulliken charge on the nitro oxygen atom and to the partition coefficient log P value. The equation for the insecticidal versus neuroblocking potencies indicated that both potencies are related proportionally with each other when the other factors are the same.     

Design, synthesis, bioactivity, and structure-activity relationship (SAR) studies of novel benzoylphenylureas containing oxime ether group

Novel benzoylphenylureas containing an oxime ether group were designed and synthesized by four schemes. These benzoylphenylureas were identified by (1)H NMR spectroscopy and element analysis (or HRMS). The bioactivities of the new compounds were evaluated. These benzoylphenylureas exhibited excellent larvicidal activities against oriental armyworm, some of which were much better in comparison with the commercial Flucycloxuron. In particular, the larvicidal activities against oriental armyworm of compounds 1 and 23 were 5-10 times better than that of Flucycloxuron. Most of these benzoylphenyureas exhibited excellent larvicidal activities against mosquito. At the same time, some of these compounds have good plant growth regulatory activities as well.     

Green tea polyphenols inhibit metalloproteinase activities in the skin,muscle, and blood of rainbow trout

We have investigated the inhibitory effects of polyphenols from natural products, such as green tea, bilberry, grape, ginkgo, and apple, on rainbow trout gelatinase activities. Gelatinases from the skin, muscle, and blood of rainbow trout contained serine proteinase, metalloproteinase, and other proteinase activities as measured by gelatin zymography. The polyphenols of green tea caused the strong inhibition of some gelatinase activities when compared with those of the other products. This inhibition was quite similar to that of metalloproteinase by ethylenediaminetetraacetic acid, suggesting that the effects of green tea polyphenols on proteinase activities are specific for metalloproteinases. The major catechins of green tea polyphenols were then separated and identified by reverse-phase chromatography to be (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epicatechin. The effects of these catechins on gelatinase activities were examined; the most potent inhibitor of metalloproteinase activities was found to be EGCG. These results have indicated that green tea polyphenols including EGCG are useful for regulating metalloproteinase activities of fish meat.     

Effects of Garlic Bulb Aqueous Extract on Cucumber Seedlings,Soil Microbial Counts,and Enzyme Activities

The effects of the aqueous extract of garlic bulbs on cucumber seed germination, seedling growth, soil microbial counts, and soil enzyme activities were investigated using a bioassay test and a pot experiment. Garlic bulb extracts impacted cucumber seed germination and seedling growth but had no significant effects at low concentration. Polyphenol oxidase, saccharase, urease, and catalase activities were increased significantly at all concentrations of aqueous extract tested in the soil. Bacterial counts were increased by garlic bulb extract and trends of actinomycete counts were the same as for bacterial counts. Fungal counts were significantly depressed with increasing concentration of garlic bulb extract. Polyphenol oxidase activity showed significant positive correlations with catalase, saccharase, and urease activities and counts of actinomycetes and a significant negative correlation with fungal counts. The results indicate that garlic may be effective in reducing some obstacles of continuous cropping through its potential effects in appropriate culture systems.     

Synthesis, crystal structure, and biological activities of 2-cyanoacrylates containing furan or tetrahydrofuran moieties

A series of novel cyanoacrylates containing furan or tetrahydrofuran moieties were synthesized, and their structures were characterized by 1H NMR, elemental analysis, and single-crystal X-ray diffraction analysis. The herbicidal, plant growth regulatory, fungicidal, and antiviral activities of these cyanoacrylates were evaluated. The results of herbicidal activities showed that most of these cyanoacrylates exhibited higher herbicidal activities against dicotyledonous weeds than monocotyl-edonous weeds, and the compounds containing the tetrahydrofuran moiety gave higher herbicidal activities than corresponding furan analogues; (Z)-ethoxyethyl 2-cyano-3-isopropyl-3-(tetrahydrofuran-3-yl)methaneaminoacrylate showed excellent herbicidal activities against amaranth pigweed in postemergence treatment at a dose of 375 g/ha. At the same time, these cyanoacrylates had interesting plant growth regulatory activities, and some compounds stimulated radicle growth of cucumber, whereas some compounds had an inhibitory effect. These cyanoacrylates showed fungicidal activities as well.     

Extraction,purification and properties of soil hydrolases

Invertase, cellulase, phosphatases, protease and β-glucosidase were extracted from permanent pasture soil with 0.2 M phosphate buffer (pH 8) in the presence of 0.2 M EDTA. This extract was further treated with ammonium and salmine sulphates. Attempts were made to fractionate these enzyme activities by gel and anion-exchange chromatography. Specific activities were estimated in all fractions and some characteristics of the purified enzymes (optimum pH, temperature and substrate concentration, and K_m and V_max) were investigated. The results indicated that extracted enzyme activities occurred partly in soil as a carbohydrate-enzyme complex and partly as a humo-carbohydrate complex.     

Urease,invertase, dehydrogenase and polyphenoloxidase activities in paddy soil influenced by allelopathic rice variety

Allelopathic rice variety can release allelochemicals from roots to soil in which interfere with neighboring plant and microbial species, but little is currently known about their effect on enzyme activities of paddy soils. This study showed that enzyme activities and concentrations of allelochemicals in paddy field varied with rice varieties, growth stages and moisture regime. Allelopathic rice variety PI312777 paddy fields had higher levels of soil urease, invertase, dehydrogenase and polyphenoloxidase activities when compared to non-allelopathic rice variety Liaojing-9. Furthermore, allelopathic PI312777 released much higher concentrations of allelochemical 5,7,4′-trihydroxy-3′,5′-dimethoxyflavone than non-allelopathic Liaojing-9 during the whole growth stages. Both rice root exudates and the flavone changed soil enzyme activities, but their effects could be distinguished by allelopathic PI312777 and non-allelopathic Liaojing-9 varieties tested. There was a correlation with concentrations of the flavone and enzyme activities in rice soil. The flavone increased enzyme activities, but all test enzyme activities were less responsive to the flavone in flooded soil than in non-flooded soil. The flavone given the short half-life easily degraded in rice soil, but the flavone was more resistant toward degradation in non-flooded soil. These results suggest that the urease, invertase, dehydrogenase and polyphenoloxidase activities of paddy soils may be positively influenced by allelopathic rice variety through the release of allelochemicals.     

Synthesis, insecticidal, and acaricidal activities of novel 2-aryl-pyrrole derivatives containing ester groups

A series of novel 2-aryl-pyrrole derivatives containing ester groups were synthesized, and their structures were characterized by (1)H NMR spectroscopy and elemental analysis. The insecticidal activities against oriental armyworm, mosquito, diamondback moth, green rice leafhopper, and bean aphids and acaricidal activities against spider mite of these new compounds were evaluated. The results of bioassays indicated that some of these title compounds exhibited excellent insecticidal and acaricidal activities. The insecticidal activities against oriental armyworm of compounds IVa, IVd, IVe, IVf, IVg, IVi, IVk, and IVp were equal to commercialized Chlorfenapyr, and the insecticidal activities of most of compounds IVb, IVc, IVd, IVf, IVg, IVj, IVk, IVl, IVs, IVt, IVu, IVw, IVx, IVz, and Chlorfenapyr against mosquito at 0.10 mg kg (-1) were 100%, and the acaricidal activities of compounds IVd, IVe, IVf, IVg, IVh, IVi, and IVk were equal or superior to Chlorfenapyr. Especially, the results indicated that the acaricidal activity of [4-bromo-2-(4-chlorophenyl)-3-cyano-5-(trifluoromethyl)pyrrol-1-yl]methyl 3-methylbutanoate ( IVg) against spider mite was 2.65-fold as high as that of Chlorfenapyr from the value of LC 50.     

Metabolites from Aspergillus fumigatus, an endophytic fungus associated with Melia azedarach, and their antifungal, antifeedant, and toxic activities

Thirty-nine fungal metabolites 1-39, including two new alkaloids, 12β-hydroxy-13α-methoxyverruculogen TR-2 (6) and 3-hydroxyfumiquinazoline A (16), were isolated from the fermentation broth of Aspergillus fumigatus LN-4, an endophytic fungus isolated from the stem bark of Melia azedarach. Their structures were elucidated on the basis of detailed spectroscopic analysis (mass spectrometry and one- and two-dimensional NMR experiments) and by comparison of their NMR data with those reported in the literature. These isolated compounds were evaluated for in vitro antifungal activities against some phytopathogenic fungi, toxicity against brine shrimps, and antifeedant activities against armyworm larvae (Mythimna separata Walker). Among them, sixteen compounds showed potent antifungal activities against phytopathogenic fungi (Botrytis cinerea, Alternaria solani, Alternaria alternata, Colletotrichum gloeosporioides, Fusarium solani, Fusarium oxysporum f. sp. niveum, Fusarium oxysporum f. sp. vasinfectum, and Gibberella saubinettii), and four of them, 12β-hydroxy-13α-methoxyverruculogen TR-2 (6), fumitremorgin B (7), verruculogen (8), and helvolic acid (39), exhibited antifungal activities with MIC values of 6.25-50 μg/mL, which were comparable to the two positive controls carbendazim and hymexazol. In addition, of eighteen that exerted moderate lethality toward brine shrimps, compounds 7 and 8 both showed significant toxicities with median lethal concentration (LC(50)) values of 13.6 and 15.8 μg/mL, respectively. Furthermore, among nine metabolites that were found to possess antifeedant activity against armyworm larvae, compounds 7 and 8 gave the best activity with antifeedant indexes (AFI) of 50.0% and 55.0%, respectively. Structure-activity relationships of the metabolites were also discussed.     

Amidase and urease activity in soil as affected by sludge,salinity and wetting and drying cycles

Three incubation experiments were carried out to assess the effect of different levels of sludge, salinity and of different wetting and drying cycles on amidase and urease activity in a calcareous silt loam soil. Both amidase and urease activities were largely increased with the increase in the amount of sludge applied. The addition of NH₄⁺ - N with sludge slightly reduced both activities. Addition of increasing amounts of a 1:1 NaCl: CaCl₂ salt mixture increasingly reduced the soil activities of amidase and urease. This effect was less severe in sludge amended soil. The data also showed that drying of either unamended or sludge amended soil cause a marked drop in amidase and urease activity. Rewetting increased both enzyme activities.     

Synthesis, crystal structure, and insecticidal activity of novel N-alkyloxyoxalyl derivatives of 2-arylpyrrole

Two series of novel N-alkyloxyoxalyl derivatives of 2-arylpyrrole were synthesized, and their structures were characterized by (1)H NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis. The insecticidal activities of the new compounds were evaluated. The results of bioassays indicated that some of these title compounds exhibited excellent insecticidal activities, and their insecticidal activities against oriental armyworm, mosquito, and spider mite are comparable to those of the commercialized Chlorfenapyr.     

Total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone

The total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone, were determined. Grape seed and green tea were analyzed for their phenolic constituents using high-performance liquid chromatography. The total phenolics of the plant extracts, determined by the Folin-Ciocalteu method, ranged from 24.8 to 92.5 mg of chlorogenic acid equivalent/g dry material. The antioxidant activities of methanolic extracts determined by conjugated diene measurement of methyl linoleate were 3.4-86.3%. The antioxidant activity of the extracts using chicken fat by an oxidative stability instrument (4.6-10.2 h of induction time) followed a similar trend in antioxidant activity as determined by the Folin-Ciocalteu method. Seven phenolics in grape seed and green tea extracts were identified that ranged from 15.38 to 1158.49 and 18.3 to 1087.02 mg/100 g of extract, respectively. Plant extracts such as green tea and grape seed extracts can be used to retard lipid oxidation in a variety of food products.     

秸秆对根区土壤酶活性、无机氮及呼吸量的影响

采用田间小区试验和室内土壤培养相结合的方法,研究了秸秆对根区土壤酶活性、无机氮总量和呼吸量的影响。结果表明:秸秆的加入,使土壤脲酶活性和蔗糖酶活性升高,过氧化氢酶活性与秸秆加入量达显著差异,但其活性随培养时间的延长而逐渐降低;土壤多酚氧化酶活性与其它酶活性变化规律不同,大豆田土壤多酚氧化酶活性高于玉米田多酚氧化酶活性。土壤无机氮含量随培养时间的延长而增加,其中大豆田土壤加入秸秆后,处理间没有显著差异,而玉米田土壤差异显著。各处理间土壤呼吸总量与秸秆加入量均达差异显著水平,玉米田土壤高于大豆田土壤。相关性分析表明,玉米田土壤4种酶活性与无机氮和呼吸量均呈显著相关,而大豆田土壤脲酶、多酚氧化酶活性与土壤无机氮均呈极显著相关。因此,秸秆的加入可以促进土壤微生物的活动,提高了土壤酶活性、无机氮的含量及呼吸量。     

Enzyme activities in semiarid soils under conservation reserve program,native rangeland,and cropland

There is limited knowledge of biochemical processes in low carbon content soils of semiarid regions under different land use and management. This study investigated several enzyme activities of C, N, P, and S transformations in semiarid soils with different clay (10–21 %) and sand (59–85 %) contents that were under conservation reserve program (CRP), native rangeland (NR), and cropland (CL) under sunflowers (Eriophyllum ambiguum (Gray)), continuous cotton (Gossypium hirsutum L.), or in rotations with wheat (Triticum aestivum L.) or sorghum (Sorghum bicolor L.) in West Texas, USA. Soils under CRP and NR showed higher total C and N contents than cultivated soils under continuous cotton, but soil pH (6.7–8.4) was not affected by the management or land use studied. The activities of β‐glucosidase, β‐glucosaminidase, arylamidase, acid and alkaline phosphatase, phosphodiesterase, and arylsulfatase (mg product (kg soil)^–1 h^–1) were lower in CL under continuous cotton compared to cotton in rotation with other crops, CRP, and NR. The enzyme activities were also lower when compared to soils from other regions. Linear regression analyses indicated positive correlations between enzyme activities and total C (r values up to 0.96, P < 0.01). There was a positive relationship between enzyme activities and total N, but soil pH showed the opposite trend. Enzyme activities were significantly intercorrelated with r values up to 0.98 (P < 0.001). The specific enzyme activities (mg product (g organic C)^–1) were lower in continuous cotton in comparison to the uncultivated soils (i.e., NR and CRP) reflecting differences in organic matter quantity and quality due to cultivation. Among the enzymes studied, the specific activities of β‐glucosidase and arylamidase showed a more pronounced decrease with increasing soil depth. In general, soils under CRP or wheat‐cotton rotations revealed higher enzyme activities than soils under the common agricultural practice for these regions, i.e., continuous cotton under conventional tillage.     

Synthesis, fungicidal, and insecticidal activities of beta-Methoxyacrylate-containing N-acetyl pyrazoline derivatives

1-Acetyl-3,-5-diarylpyrazolines have received considerable interests from the fields of medicinal and agricultural chemistry due to their broad spectrum of biological activities. To discover new lead compounds exhibiting both fungicidal and insecticidal activities, a series of pyrazoline derivatives were designed and synthesized by introducing the beta-methoxyacrylate pharmacophore into the scaffold of 1-acetyl-3,5-diarylpyrazoline. The fungicidal activities against Pseudoperoniospora cubensis, Sphaerotheca fuliginea, Botrytis cinerea, and Rhizoctonia solani and the insecticidal activities against Aphis medicagini, Nilaparvata legen, Mythima separata, and Tetranychus cinnabarnus were screened. The most potent compound 13, 1-aceto-3-[m-[o-(E-1-methoxycarboxyl-2-methoxy)-1-yl]benzyloxy]phenyl-5-(benzo-[1,3]-dioxolyl)-4,5-dihydro- pyrazoline, was identified. Its fungicidal IC(50) values against P. cubensis and S. fuliginea are 26.6 and 57.6 microg mL(-1), respectively, while its insecticidal LC(50) value against M. separata is 26.6 microg mL(-1). These results indicated that compound 13 could be used as a lead for further developing new pyrazoline type products exhibiting both fungicidal and insecticidal activities.     

氯嘧磺隆对土壤微生物数量,酶活性及呼吸强度的影响

氯嘧磺隆是一类高效广谱除草剂,研究其对土壤微生物的影响对其合理使用具有重要意义。通过室内瓶培养实验研究了不同浓度氯嘧磺隆对土壤呼吸强度、土壤微生物数量和土壤酶活性的影响。结果表明:氯嘧磺隆施入土壤2周后,可明显提高土壤呼吸强度,且浓度越大,提高效果越明显;氯嘧磺隆施入土壤1周后,不同浓度氯嘧磺隆处理均可提高土壤细菌和放线菌数量,45 d时表现出抑制作用,60 d可恢复到对照水平;氯嘧磺隆对土壤真菌数量表现为抑制作用,而后恢复到对照水平,45 d时田间施用量可抑制土壤真菌的增殖,但60 d可恢复到对照水平。土壤培养前1周,氯嘧磺对土壤过氧化氢酶、土壤转化酶、土壤脲酶活性均表现出不同程度的抑制作用,且浓度越大抑制作用越明显。之后三种酶表现出一定的激活作用,培养60 d可恢复到对照水平。以上试验结果可为合理施用氯嘧磺隆提供理论依据。     

Root zone microbial populations, urease activities, and purification efficiency for a constructed wetland

In order to investigate the effects of microorganisms and their urease activities in macrophytic root zones on pollutant removal, four small-scale plots (SSPs) of vertical/reverse-vertical flow wetlands were set up to determine: a) the relationship between the abundance of microorganisms in the root zones and water purification efficiency; and b) the relationship between urease activities in the root zones and pollutant removal in a constructed wetland system. Total numbers of the microbial population (bacteria, fungi, and actinomyces) along with urease activities in the macrophytic root zones were determined. In addition, the relationships between microbial populations and urease activities as well as the wastewater purification efficiencies of total phosphorus (TP), total Kjeldahl nitrogen (TKN), biochemical oxygen demand in 5 days (BOD₅), and chemical oxygen demand (COD) were also analyzed. The results showed that there was a highly significant positive correlation (r = 0.9772, P < 0.01) between the number of bacteria in the root zones and BOD₅ removal efficiency and a significant negative correlation (r = -0.9092, P < 0.05) between the number of fungi and the removal efficiency of TKN. Meanwhile, there was a significant positive correlation (r = 0.8830, P < 0.05) between urease activities in the root zones and the removal efficiency of TKN. Thus, during wastewater treatment in a constructed wetland system, microorganism and urease activities in the root zones were very important factors.