Extraction of Pumpkin Polysaccharide by Complex Enzyme Method and Its Antioxidant Research

[Objective] This paper aims to study a new method of extracting pumpkin polysaccharide from pumpkin. Single factor experiments were conducted to examine the effects of extracting time,temperature,the solid-liquid ratio and pH value on the extraction yield of polysaccharide from pumpkin. [Method] The best enzyme ratio and extraction conditions for complex enzymes extraction were determined through orthogonal tests. Scavenging ·OH and O-2 activities of pumpkin polysaccharides were also investigated by salicylic acid and improved self-oxidation of o-pheno methods respectively. [Results] The results showed that the biggest extraction yield of polysaccharide from pumpkin can be got when adding 1% cellulose enzyme,1.5% pectinase,1.0% papain and Na2HPO4-citric acid buffer solution (pH was 4.6),and oscillating for 30 min under water at 40 ℃ with the solid-liquid ratio of 1:30. In addition,pumpkin polysaccharides had a strong activity of eliminating ·OH,but very weak activity to scavenge O-2. [Conclusion] This study provided basic data for research and application of Pumpkin polysaccharide.

Metabolic enzyme inhibitory abilities, in vivo hypoglycemic ability of palmleaf raspberry fruits extracts and identification of hypoglycemic compounds

The unripe palmleaf raspberry,namely Fupenzi(FPZ),is an important medicinal and edible food.This study aims to evaluate the potential of FPZ extracts prepared with different approaches in attenuating hyperglycemia,gout,Alzheimer’s disease,and pigmentation,to obtain the enriching fraction and to identify the major active compounds.Results indicated that FPZ extracts showed weak activity against acetylcholinesterase,considerable ability against tyrosinase and xanthine oxidase,but excellent inhibition onα-glucosidase.Ultrasound-assisted 40%ethanol extract(40EUS)gave the highest phenolics content,and the bestα-glucosidase inhibition(IC_(50)=0.08μg/mL),which is 877-fold higher than that of positive control acarbose.The 40%ethanol eluting fraction of 40EUS showed the strongestα-glucosidase inhibition with the IC_(50) value of 37.79 ng/mL,it could also effectively attenuate the fasting blood glucose level and oral glucose tolerance of C57BL/6 mice.Twenty-six compounds were identified from 40%ethanol fraction by using HPLC-QTOF-MS/MS,hydrolysable tannins(including 11 ellagitannins and 4 gallotannins)were the major compounds,phenolic acids came to the second.Above results could provide important technical supporting for the further application and research of FPZ in health foods and drugs against diabetes.

Enzyme extraction by ultrasound from sludge flocs

Enzymes play essential roles in the biological processes of sludge treatment. In this article, the ultrasound method to extract enzymes from sludge flocs was presented. Results showed that using ultrasound method at 20 kHz could extract more types of enzymes than that at 40 kHz and ethylenediamine tetraacetic acid （EDTA） methods. The optimum parameters of ultrasound extraction at 20 kHz were duration of 10 min and intensity of 552 W/g TSS. Under the optimum condition, ultrasound could break the cells and extract both the extracellular and a small part of intercellular enzymes. Ultrasound intensity was apparently more susceptive to enzyme extraction than duration, suggesting that the control of intensity during ultrasound extraction was more important than that of duration. The Pearson correlation analysis between enzyme activities and cation contents revealed that the different types of enzymes had distinct cation binding characteristics.

Optimization of enzyme assisted extraction of polysaccharides from Ganoderma lucidum

In the present work,an enzyme assisted extraction method is used to isolate crude polysaccharides from Ganoderma lucidum. The isolating effect was optimized with orthographic graph statistic method with three levels and four independent variables. Complex enzyme,extraction temperature,extraction time and extraction pH were combined to obtain the best possible combination to get maximum amount of extract and crude polysaccharides yield. The optimum extraction conditions were:complex enzyme amount of 3 %(w/v),extraction temperature at 45 ℃,extraction time of 3 h and extraction pH at 7. Under these conditions,the experimental amount of extract is 8.9 % and the yield of crude polysaccharides is 1.1 %,which are in close agreement with the value predicted by the model.

Metal Salts Assisted Enzyme-Based Extraction of Stevioside from the Leaves of <i>Stevia rebaudiana</i>Bertoni

Stevioside, extracted from the leaves of Stevia rebaudiana Bertoni, is a natural, high intensity, lowcaloric sweetener with wide therapeutic activities. Conventional stevioside extraction methodologies involve the use of non-green solvents, supercritical fluids, microwaves, etc., however, all these processes are expensive, time-consuming and eco-unfriendly. Therefore an alternative process is desired for the isolation of stevioside. In this study, a novel enzyme-mediated extraction (EME) method has been developed. The dry stevia leaves were pre-treated with hydrolytic enzymes aided by transition metal salts (FeCl3). This was followed by pressurized hot water extraction (PHWE) to release stevioside. The crude extract was purified and clarified through multi-stage membrane filtration. The results confirm that metal salt-assisted cellulase pre-treatment enhanced the yield of stevioside to 72%, with 98% purity, which was higher in comparison to existing methods. Thus, the methodology developed establishes a simple, “green”, enzyme-mediated process for the efficient isolation of stevioside under economical and eco-friendly conditions.

Effect of plant extracts on activity of some defense enzymes of apple fruit in interaction with Botrytis cinerea

The efficacy of seven plant extracts(neem,fennel,lavender,thyme,pennyroyal,salvia and asafetida) in controlling postharvest of apple(caused by Botrytis cinerea) was evaluated in vitro and in vivo.In vitro,all plant extracts treatments inhibited spore germination.Inhibitory rates of pore germination was 17.41 and 20.83% for neem extract treatment(methanolic and aqueous extracts,respectively) with significant difference compared to control(73.6 and 85.33%) for aqueous and methanol extracts.In the storage conditions,the application of aqueous extract of neem(at concentration of 25%) resulted in 89.11% reduction of disease severity compared with the untreated control.Results of enzymes activity showed the plant extracts can increase the activity of peroxidase,phenylalanine ammonia-lyase,β-1,3-glucanase and polyphenol oxidase in the presence of pathogens,in apple fruits.However,the results of this research revealed that application of neem extracts was more effective than the application of other plant extracts.According to this study,it could be concluded that plant extracts may be useful to control postharvest disease as a safe alternative option to chemical fungicides.

Characteristics, Enzymatic Extraction of Pectin from Shaddock

Pectins had been extracted from shaddock raw material with 0.01 mol·L^-1 HCI and with three enzymic preparations including cellulase from aspergillus oryzaei.β -glucosidase from almonds and protopectinases-T, a protopectin-solubilizing enzyme, which did not degrade polygalacturonic acid, The effects of enzymic and acid soluhilization of pectin from shaddock materials were compared, The yield of pectin preparations, degree of acetylation, gelling strength, molecular weight and viscosity were determined. Enzymic methods of extraction gave much bigger yields of pectic substances. Compared with the pectin extracted with hydrochloric acid, all the samples derived from shaddock raw material with enzymic preparations had a significant lower D-galacturonic acid content.

In vitro and in vivo cytochrome P450 3A enzyme inhibition by Aframomum melengueta and Dennettia tripetala extracts

Objective: To evaluate the in vitro and in vivo inhibitory effects of two commonly used herbs, Aframomum melengueta(A. melengueta) and Dennettia tripetala(D. tripetala) on CYP 3A enzymes. Methods: In vitro inhibition of the enzymes were assessed with microsomes extracted from female albino rats using erythromycin-N-demethylation assay(EMND) method while their in vivo effects were measured by estimating simvastatin plasma concentrations in rats. Pharmacokinetic parameters were determined using non-compartmental anaysis as implemented in Win Nonlin pharmacokinetic program. Results: EMND assay with intestinal microsomes indicated that aqueous extracts of D. tripetala and A. melengueta significantly(P < 0.05) inhibited intestinal CYP 3A activity at both 50 μg and 100 μg concentrations. Petroleum ether extract of D. tripetala and ethanol extracts of A. melengueta inhibited intestinal CYP3 A activity at 100 μg but not at 50 μg concentrations. All the extracts showed an in vitrodose dependent CYP 3A inhibition with liver microsomes. In vivo analysis showed that pretreatment with the extracts enhanced systemic absorption of simvastatin with reductions in metabolizing enzymes activity as indicated in significant increases in maximal concentration, area under curve, area under moment curve and mean resident time of simvastatin(P < 0.05). Conclusions: Herbal preparations containing these plants' extracts should be used with caution especially in patients on CYP450 3A substrate medications.

Efficient hepatoprotective activity of cranberry extract against CCl_4-induced hepatotoxicity in Wistar albino rat model: Down-regulation of liver enzymes and strong antioxidant activity

ObjectiveTo investigate the hepatoprotective efficacy of cranberry extract (CBE) against carbon tetrachloride (CCl4)-induced hepatic injury using in-vivo animal model.MethodsThe hepatoprotective efficacy of CBE (200 and 400 mg/kg) was investigated against CCl4 (4 mL/kg)-induced hepatotoxicity, elevated liver enzymes [ALT (alanine aminotransferase), AST (aspartate aminotransferase), and alkaline phosphatase (ALP)], and total protein (TP) contents in the serum. Moreover, CBE-aided antioxidant defense against hepatotoxic insult of CCl4 was measured by evaluating a number of anti-oxidative biomarkers including reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) in the serum by using spectrophotometric analyses.ResultsResults showed that the exposure of experimental animals to CCl4 did induce significant hepatotoxicity compared to the non-induced (untreated) group. The oral administration of CBE demonstrated a significant dose-dependent alleviation in the liver enzymes (AST, ALT, and ALP), increased antioxidant defense (GSH, SOD, and CAT), and reduced MDA levels in the serum of treated animals compared to the animals without treatment. The resulting data showed that the administration of CBE decreased the serum levels of ALT, AST, and ALP compared to the CCl4-induced group.ConclusionsThe resulting data evidenced that CBE exhibits promising hepatoprotective potential against the chemical induced hepatotoxicity, maintains homeostasis in liver enzymes, and can provide significant antioxidant defense against free radicals-induced oxidative stress.

Effects of broccoli extract and various essential oils on intestinal and faecal microflora and on xenobiotic enzymes and the antioxidant system of piglets

Objective: Since the ban of antibiotics as growth promoting feed additives in the EU in 2006 research in alternatives has gained importance. Phytogenic feed additives represent a heterogenous class of different plant derived substances that are discussed to improve the health of farm animals by direct and indirect antioxidant effects and by influencing microbial eubiosis in the gastrointestinal tract. Consequently our study aimed to investigate the influence of broccoli extract and the essential oils of tur- meric, oregano, thyme and rosemary, as selected individual additives, on intestinal and faecal microflora, on xenobiotic enzymes, and on the antioxidant system of piglets. Methods: 48 four weeks old male weaned piglets were assigned to 6 groups of 8. The piglets were housed individually in stainless steel pens with slatted floor. The control group (Con) was fed a diet without an additive for 4 weeks. The diet of group BE contained 0.15 g/kg sulforaphane in form of a broccoli extract. 535, 282, 373 and 476 mg/kg of the essential oils of turmeric (Cuo), oregano (Oo), thyme (To) and rosemary (Ro) were added to the diets of the remaining 4 groups to stan-dardise supplementation to 150 mg/kg of the oils’ key terpene compounds ar-turmerone, carvacrol, thymol and 1,8-cineole. The composition of bacterial microflora was examined by cultivating samples of jejeunal and colonic mucosa and of faeces under specific conditions. The mRNA expression of xenobiotic and antioxidant enzymes was determined by reversing transcrip- tase real time detection PCR (RT-PCR). Total antioxidant status was assayed using the Trolox Equivalent Antioxidant Capacity (TEAC), and lipid peroxidation was determined by measuring thiobarbioturic acid reactive substances (TBA- RS). Results: Compared to Con piglets all additives positively influenced weight gain and feed conversion in week 1. Over the whole trial period no significant differences in performance parameters existed between the experimental groups. Compared to group Con performance of Ro piglets was, however, slightly impaired. Com- pared to Con piglets Cuo, Oo and To increased the ratio of Lactobacilli:E. coli attached to the jejunal mucosa, whereas BE and Ro impaired this ratio slightly. In contrast in colonic mucosa Ro improved Lactobacilli:E. coli ratio. In faecal samples an improvement of Lactobacilli:E. coli ratio could be analysed for To and Ro. Ro was the only additive that reduced the incidence rate of piglets tested positive for enterotoxic E. coli (ETEC). All additives significantly increased jejunal TEAC and reduced TBA-RS. In the liver BE, Cuo, Oo and To increased TEAC in tendency and Ro significantly. Liver TBA-RS were slightly reduced by all additives compared to Con piglets. Whereas the influence of BE, To and Ro on jejunal TEAC mainly was derived from the induction of xenobiotic and antioxidant enzymes (indirect antioxidant effects), Cuo and Oo influenced TEAC by direct antioxidant effects. Discussion and Conclusions: Our results have shown: That within the labiatae oils Oo and To have the potential to improve performance slightly. That phytogenic substances have a small but not sig- nificant influence on intestinal microflora. That phytogenic feed additives up-regulate the anti- oxidant system of piglets either by direct or by indirect antioxidant effects and that they may thereby improve health status. That within the labiatae oils Oo has a high direct antioxidant potential whereas Ro potently induces xenobiotic and antioxidant enzymes. That broccoli extract is an attractive new phytogenic additive, improving antioxidant status by indirect antioxidant effects. That defined combinations of selected phytogenic substances may produce additive effects. That health promoting effects of phytogenic additives in the future should be studied systematically under the challenge with pathogenic microorganisms or food derived to-xins.

Effects of Maca Extract on Endurance and Blood Antioxidant Enzyme Activity of Rats

[Objectives] The aim was to investigate the effects of maca extract on endurance and blood antioxidative enzyme activity of rats.[Methods]The Wistar rats treated with/without maca extract( 8. 0,16. 0,and 32. 0 g/kg) were given with free access to circulating water.The administration was conducted for 15 consecutive d. On the 16 th d,the endurance and blood malondialdehyde( MDA),superoxide dismutase( SOD) and glutathione peroxidase( GSH-Px) levels of the rats were determined. [Results] Compared with those of the rats without maca extract treatment,the swimming time before sinking of the rats administered with 8. 0,16. 0,and 32. 0 g/kg of maca extract was increased by 34. 38%,84. 25% and 126. 07%( P < 0. 01),the total swimming time was increased by 37. 42%,47. 03% and 107. 24%( P <0. 01),the times of sinking was reduced by 17. 65%,33. 28% and 55. 50%( P < 0. 05,P < 0. 01),the blood MDA level was reduced by 34.63%,54. 13% and 63. 73%( P < 0. 01),the blood SOD activity was increased by 67. 78%,108. 25% and 154. 49%( P < 0. 01),and the blood GSH-Px level was increased by 48. 57%,110. 28% and 154. 86%( P < 0. 01). [Conclusions]Maca extract has the functions of resisting fatigue and enhancing athletic,and the mechanisms are related to the reduction of blood MDA level and the increase of blood SOD and GSH-Px activity.

Comparison of the antitumor activity of polysaccharides extracted by boiling water and enzyme assistance from Ganoderma lucidum

Polysaccharides are the most important pharmacologically active constituents of Ganoderma lucidum. In this work, polysaccharides were extracted from Ganoderma lucidum with boiling water method and enzyme assisted method. The human liver hepatocellular carcinoma cell line HepG2 was used to compare the an- titumor effect of the two kinds of extraction with 3-（4, 5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） test. Both of these two kinds of Ganoderma lucidum polysaccharides reduced cell viability of cancer cell HepG2 in a dose and time-dependent manner. At low concentrations, there was no significant difference in the effectiveness of L 1 and L2; while at concentrations over 0.8 ug/mL, the difference in the effectiveness of L2 in comparison to L1 became significant. At the concentrations of 3.2 ug/mL, the cancer cells were almost killed in 2 d.

Comparative study on yields and quality parameters of argan oils extracted by conventional and green extraction techniques

Argan oil is most frequently sold as pure oil,which can be directly applied topically due to its cosmetological proprieties or ingested in order to provide several health benefits.It's also commonly mixed into a number of cosmetic products like shampoos,soaps and conditioners.In this study we aimed to improve the argan oil extraction yield and quality parameters by comparing the effects of different extraction technologies.Argan kernel oils were extracted using four methods:mechanical cold press,Soxhlet extraction with n-hexane,supercritical fluid extraction(SFE),and enzyme assisted extraction with three different enzyme solutions cellulase(cellulast),pectinase(Pectinex)and a mixture of carbohydrase enzymes(Viscozyme®).The quality parameters was evaluated by determining the acid,peroxide and iodine values aswell as the extinction coefficients K_(232) and K_(270) as measures of conjugated dienes and trienes,respectively.The results showed that the highest yield(66.37%±3.3%)was obtained by enzyme assisted extraction using the carbohydrases enzymes mixture(Viscozyme®),followed by Soxhlet extraction(59.5%±3.1%)and pectinase extraction(52.03%±3.55%).All argan oils samples obtained by the different methods showed a good oxidation stability,with acid,peroxide and iodine values lower than 0.8 mg/g,15 meq/kg and 110 g/100 g according to the official argan oil norm,respectively.The results of argan oils quality parameters demonstrated that the enzyme extracted argan oils showed low oxidation,with the following quality parameters:acid values(0.4-0.6 mg/g),iodine values(95-100 g/100 g),dienes(K_(232)<2),trienes(K_(270)<0.35),and peroxide values(<1.5 meq/kg).The results proved that the enzyme assisted extraction method can be applied to improve the argan oil yield without affecting the oil quality.The enzyme extraction method may be a great alternative to solvent and cold press extractions for this eco-friendly processing approach.

Effect of dietary magnolia bark extract supplementation in finishing pigs on the oxidative stability of meat

Background:Magnolia bark extract(MBE)is a natural supplement with antioxidant,anti-inflammatory,and antimicrobial activities.Its properties suggest that the dietary supplementation in livestock could improve the quality of products.Therefore,the aim of this study was to investigate,for the first time,the effect of dietary MBE supplementation(0.33 mg/kg)in finishing pigs on the oxidative stability of meat.Oxidative stability is of paramount importance for pork,as it affects storage,retail,and consumer acceptance.For the purpose,the fatty acid profile,cholesterol,fatsoluble vitamins,antioxidant enzymes(catalase,glutathione peroxidase,and superoxide dismutase),non-enzymatic antioxidant capacity(TEAC,FRAP,and Folin-Ciocalteu assays),color stability,and lipid stability of pork were assessed.Results:Concerning carcass characteristics,dietary MBE did not affect cold carcass yield,but reduced(P=0.040)the chilling weight loss.The meat from pigs fed MBE had a lower(P=0.031)lightness index than the control meat.No effect on intramuscular fat,cholesterol,and fatty acid profile was observed.Dietary MBE did not affect the content of vitamin E(α-tocopherol andγ-tocopherol)in pork,whereas it reduced(P=0.021)the retinol content.The catalase activity was 18%higher(P=0.008)in the meat from pigs fed MBE compared with the control group.The MBE supplementation reduced(P=0.039)by 30%the thiobarbituric acid reactive substances(TBARS)in raw pork over 6 d of aerobic refrigerated storage.Instead,no effect on lipid oxidation was observed in cooked pork.Last,the meat from pigs fed MBE reduced Fe3+-ascorbate catalyzed lipid oxidation in muscle homogenates,with a lower(P=0.034)TBARS value than the control group after 60 min of incubation.Conclusions:Dietary MBE supplementation in finishing pigs delayed the lipid oxidation in raw meat.This effect was combined with an increased catalase concentration.These results suggest that dietary MBE could have implications for improving the shelf-life of pork.

松籽油水酶法提取及酶法破乳工艺研究

以压榨松籽饼粕为原料,利用水酶法提取松籽油,通过单因素及响应曲面试验研究松籽油提取工艺,并对提油过程中产生的乳状液进行破乳研究分析。结果表明,碱性蛋白酶酶解效果最佳,最优工艺为酶解时间2.5 h,温度56℃,pH值11.3,加酶量5045 U·g^(-1),此条件松籽油提油率为71.73%。经比较碱性蛋白酶添加量为3000 U·g^(-1)时破乳效果最好,破乳率为87.68%,在酶法破乳后进行酸化处理,通过调节pH值至5时破乳率提高至92.18%,此条件下松籽油得油率为70.36%。

内生真菌SDYS180粗提物抑菌活性与机制

【目的】探究内生真菌SDYS180(聚多曲霉菌Aspergillus sydowii)对常见林木病原真菌的拮抗活性及抑菌机制,旨在为生防菌的开发与利用提供依据。【方法】以前期筛选的植物内生真菌SDYS180为试验材料,通过体外试验测定其对13株常见林木病原真菌的抑制活性,并建立SDYS180粗提物对各病原真菌的毒力回归方程,同时测定SDYS180粗提物对杨树叶斑病菌生理指标[电导率、可溶性蛋白(SP)质量分数、丙二醛(MDA)浓度、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性]的影响。【结果】SDYS180菌体、发酵液和挥发性代谢产物对13株林木病原真菌的抑制效果表现为菌体>发酵液>挥发性代谢产物,其中对杨树叶斑病菌的抑制活性最佳,粗提物对该菌的毒力回归方程为y=0.301 0x+0.143 7(R^(2)=0.986 4),EC_(50)=1.183 7 mg·mL^(-1)。SDYS180粗提物对杨树叶斑病菌的生理指标存在明显影响,主要表现为:试验期间处理组的电导率和MDA浓度大于对照组,8 h时电导率最大,达到27.73 mS·cm^(-1),4 h时MDA浓度最大,达到0.183μmol·g^(-1);8 h后处理组的SP质量分数小于对照组;处理组的POD、SOD、CAT活性与对照组相比都呈现先增强后减弱的趋势,且均在4 h时达到最大值,分别为1 200 U·g^(-1)·min^(-1)、33 U·g^(-1)、5.46 U·g^(-1)·min^(-1)。【结论】SDYS180是一株具有开发潜力的生防菌。

不同方法提取罗勒籽胶的理化性质及其结构特性

采用酶法提取罗勒籽胶,通过单因素实验及响应面实验确定了最佳工艺,比较不同提取方法(常规法、微波法、超声法和酶法)对罗勒籽胶的得率、理化性质(凝胶强度、持水力、溶胀性能、颜色)、微观结构、流变特性、活性成分(总黄酮、总酚)及抗氧化性的影响。结果表明,酶法提取罗勒籽胶的最佳工艺为:以果胶酶为提取酶制剂、酶添加量4.1%(以预处理后罗勒籽质量为基准)、酶解时间30 min、酶解温度40℃、pH=5.1。在上述优化条件下,罗勒籽胶得率为12.96%;与其他3种方法相比,酶法提取罗勒籽胶得率最高、持水力最佳;微观结构表明,酶法提取的罗勒籽胶具有网络结构;动态流变温度扫描模式说明,罗勒籽胶是稳定的水胶体,其中,酶法提取的罗勒籽胶最稳定;酶法提取的罗勒籽胶能够最大程度地保留活性成分,1,1-二苯基-2-三硝基苯肼自由基清除率达到20.60%±1.44%,2,2'-联氮双(3-乙基苯并噻唑啉-6-磺酸)二铵盐自由基清除率达到8.70%±0.37%。

昆布多糖的复合酶法提取工艺优化及其对α-葡萄糖苷酶的抑制活性

优化复合酶提取昆布多糖的工艺参数,并考察其抑制α-葡萄糖苷酶的能力。以昆布多糖得率为评价指标,通过正交试验确定复合酶配比,采用响应面法评价酶解时间、pH、液料比和温度对昆布多糖得率的影响。采用体外酶抑制实验测定昆布多糖对α-葡萄糖苷酶的抑制活性。结果表明,复合酶最佳添加量为纤维素酶100 mg、果胶酶90 mg、木瓜蛋白酶55 mg,最佳酶法提取工艺为酶解时间1.8 h、酶解温度49.4℃、pH6.1、液料比59:1 mL/g,最佳工艺条件下昆布多糖预测得率18.183%,实测多糖得率18.19%±1.04%,其中性糖、酸性糖、蛋白质及硫酸根含量分别52.72%、11.76%、2.66%、19.49%;在1~5 mg/mL范围内其对α-葡萄糖苷酶的抑制作用随浓度增加而升高,最大抑制率为79.04%±3.17%,IC50为1.443 mg/mL。复合酶法提取的昆布多糖得率高,其对α-葡萄糖苷酶具有明显的抑制作用。

2种植物提取物对杂拟谷盗的生物活性及几种酶活性的影响

杂拟谷盗(Tribolium confusum)是一种重要的储粮害虫,熏蒸是目前主要的防治方法。相比化学熏蒸,植物源杀虫剂作用方式多样且对环境和粮食安全。因此本论文研究了2种植物[瑞香狼毒(Stellera chamaejasme L.)根石油醚提取物和百里香(Thymus mongolicus Ronn.)甲醇提取物]对杂拟谷盗的熏蒸、拒食和驱避活性,以及对杂拟谷盗2种靶标酶和3种解毒酶活性的影响。结果表明,瑞香狼毒根石油醚提取物和百里香甲醇提取物熏蒸杂拟谷盗24 h后,致死中浓度(Lethal concentration,LC 50)分别为88.50和119.57 mg·L^(-1);拒食处理杂拟谷盗5 d后的拒食中浓度(Antifeedant concentration,AFC 50)分别为23.00和14.78 mg·L^(-1);4 h的驱避率分别为63.49%和71.90%。2种植物提取物对杂拟谷盗乙酰胆碱酯酶和三磷酸腺苷酶活性均有抑制作用。2种植物提取物处理杂拟谷盗后,细胞色素P450和谷胱甘肽-S-转移酶活性被诱导升高,而羧酸酯酶活性降低。本试验结果为未来进一步开发利用这2种植物源农药防治储粮害虫提供了一定的理论基础。

甘蔗/花生间作对根系生理及根际土壤养分的影响

为探明甘蔗/花生间作对根系生理及根际土壤养分的影响,本文设置了甘蔗单作、花生单作、甘蔗/花生间作模式,系统分析了不同种植模式下根系分泌物、根系浸提物和根际土壤养分的变化及其相关性。结果表明:间作甘蔗根系分泌的总氨基酸及根系浸提液中的总糖显著高于单作,间作花生根系分泌的总糖显著高于单作。间作甘蔗根际土壤的碱解氮(alkali-hydrolyzed nitrogen,AN)、有效磷(available phosphorus,AP)、速效钾(available potassium,AK)和土壤有机质(soil organic matter,SOM)显著高于单作甘蔗,间作种植显著降低了花生根际土壤的有效磷、速效钾和pH。间作和单作甘蔗的酸性磷酸酶、过氧化氢酶、脲酶和蔗糖酶差异不显著,间作花生的过氧化氢酶显著高于单作花生。根系分泌的酚酸与土壤有机质呈显著负相关,总糖与蔗糖酶呈显著正相关,氨基酸与脲酶呈显著正相关;根系浸提液中的有机酸与pH呈显著正相关,氨基酸与SOM呈显著负相关、与AK呈极显著负相关。脲酶与AK呈显著负相关,蔗糖酶与SOM呈极显著负相关。综上,甘蔗/花生间作主要影响根系分泌氨基酸、总糖和酚酸的代谢活动,且可显著提高甘蔗的土壤有效养分。