Comparison of acetylcholinesterase from three field populations of Liposcelis paeta Pearman (Psocoptera: Liposcelididae): Implications of insecticide resistance

The toxicological and biochemical characteristics of acetylcholinesterases (AChE) in Liposcelis paeta Pearman were investigated in three field populations collected from Nanyang city of Henan Province (NY), Wuzhou (WZ) and Hezhou (HZ) Cities of Guangxi Province, China. The result of bioassay showed that the LC_50s of the NY (281.4802 mg/m²) and the WZ (285.0655 mg/m²) to dichlorvos were 1.156-fold and 1.171-fold higher than that of the HZ (243.5197 mg/m²), respectively. Compared to NY population, the activity per insect and the specific activity of AChE in WZ and HZ populations were significantly higher, and significant kinetic differences among the three populations were also observed. The apparent Michaelis–Menten constant (K_m) for acetylthiocholine iodide (ATChI) was obviously lower in NY than that in WZ and HZ populations, indicating a higher affinity to the substrate ATChI in the NY population. The affinity to the substrate ATChI between WZ and HZ population was also significantly different. As for V_max, the values of WZ and HZ populations were significantly greater when compared to that for NY population, suggesting a possible over expression of AChE in the former two populations. The inhibition studies of AChE indicated that paraoxon-ethyl, demeton-S-methyl, carbaryl, and eserine all possessed some inhibitory effects on AChE in L. paeta. The results of I_50S suggested that when compared to the other two populations, while AChE from HZ population was less sensitive to paraoxon-ethyl and demeton-S-methyl. The contradiction with the result of the bioassay might be due to the different insecticides used in the bioassay. Although both carbaryl and eserine had excellent inhibitory effects, there was no significant difference among the three populations. The statistical analysis of the bimolecular rate constants (k_i) was consistent with the above situation that carbamates expressed remarkable inhibitory effects. It was noticeable that NY population was most sensitive to carbaryl while least to eserine. The differences in AChE among three populations may attribute to the difference in control practices for psocids between Henan and Guangxi Provinces.     

新型含吡唑杂环邻氨基苯甲酰胺类化合物的合成与杀螨活性

以氯虫苯甲酰胺和氟虫腈的结构为基础,通过活性亚结构拼接的方法,设计合成了24个新型含吡唑杂环邻氨基苯甲酰胺类化合物,其结构经1H NM R、IR及APCI-M S表征。初步生物活性测试结果表明:化合物5-溴-N-[4-氯-2-甲基-6-(甲氨基甲酰基)苯基]-1-1-[2,6-二氯-4-(三氟甲基)苯基]-4-三氟甲基亚磺酰基-1H-吡唑-3-甲酰胺(5k)和5-溴-N-[4-溴-2-甲基-6-(甲氨基甲酰基)苯基]-1-[2,6-二氯-4-(三氟甲基)苯基]-4-三氟甲基亚磺酰基-1H-吡唑-3-甲酰胺(5l)在500 mg/L下对朱砂叶螨Tetranychus cinnabarinus的致死率为100%,但在100 mg/L下其致死率则分别降至30%和50%。所得结果可为邻氨基苯甲酰胺类化合物构效关系研究提供参考。     

Synthesis and fungicidal activities of positional isomers of the N-thienylcarboxamide

To investigate the effects of bioisosteric replacement of the phenyl group with the thienyl group, N-phenylcarboxamide and three regioisomers of N-(substituted-thienyl)carboxamide were synthesized. The inhibitory activity on the succinate dehydrogenase prepared from the gray mold Botrytis cinerea as well as the fungicidal activity against B. cinerea were evaluated. Two isomers, N-(2-substituted-3-thienyl)carboxamide and N-(4-substituted-3-thienyl)carboxamide exhibited the same level of activity as the phenyl derivative, whereas N-(3-substituted-2-thienyl)carboxamide exhibited lower activity than the phenyl derivative, suggesting that the 2-substituted-3-thienyl and 4-substituted-3-thienyl groups functioned as bioisosteres of the phenyl group in N-phenylcarboxamide, but the other did not.     

10种N-取代氨基香豆素的合成及生物活性

基于结构拼接思想,设计合成了10个N-取代氨基香豆素类化合物,并测定了其抑菌及除草活性。6-硝基香豆素经Fe/NH4Cl还原得6-氨基香豆素,再与不同醛缩合得Schiff碱,最后经硼氢化钠还原制得10个N-取代氨基香豆素类化合物(4a~4J),其中9个未见文献报道,其结构均经红外光谱、核磁共振氢谱和质谱确认。抑菌活性测试结果表明,所有化合物对苹果腐烂病菌Valsa mali、葡萄白腐病菌Coniothyrium diplodiella、棉花枯萎病菌Fusarium oxysporium和柑橘炭疽病菌Citrusanthrax bacteria均有一定抑制作用,其中 4e 的抑菌活性最强,对苹果腐烂病菌和柑橘炭疽病菌的EC50值分别为7.53和12.93 mg/L,对其余2种植物病原菌的EC50值均小于25 mg/L;化合物 4f 次之,对苹果腐烂病菌和葡萄白腐病菌的EC50值均约为11 mg/L。除草活性测试结果表明,除 4f 外,所有目标化合物均有一定除草作用,其中 4c 的活性最强,100 mg/L下对反枝苋Amaranthus retroflexus种子根、茎生长的抑制率均为99%。     

Functional analysis of mutations in expressed acetylcholinesterase that result in azinphosmethyl and carbofuran resistance in Colorado potato beetle

The functional attributes of specific point mutations, R30K, S291G, and I392T, associated with full-length acetylcholinesterase (AChE) cDNAs of organophosphate (OP)- and carbamate-resistant Colorado potato beetles (CPB), were determined using site-directed mutagenesis and baculovirus expression. Enzymatic and inhibitory properties of altered recombinant acetylcholinesterases (rAChEs) were examined. S291G increased the hydrolysis of substrates with larger substituted alkyl groups (e.g., BTC vs ATC) and increased the inhibitory action of inhibitors with larger alkyl groups (e.g., paraoxon, DFP, and N-propyl carbofuran vs. azinphosmethyl-oxon and N-methyl carbofuran). R30K in conjunction with S291G enhanced the hydrolysis activity of larger substrates and the inhibitory action of larger inhibitors. I392T attenuated the effects of S291G in that the altered rAChE with both S291G and I392T elicited substrate specificity and inhibitory properties more similar to the susceptible form of AChE without mutations.     

Protoporphyrinogen-IX Oxidase Inhibitors: Bioactivation of Thiadiazolidines

The bioactivation of thiadiazolidine-type peroxidizing compounds was examined with thiosemicarbazides as model intermediates. Peroxidizing activities of three sets of thiadiazolidines (5-arylimino-3,4-tetramethylene-1,3,4-thiadiazolidines), thiosemicarbazides (4-aryl-1-ethylthiocarbonyl-1,2-tetramethylenethiosemicarbazides), and triazolidines (4-aryl-1,2-tetramethylene-1,2,4-triazolidines) were assayed for protopor- phyrinogen-IX oxidase (Protox) inhibition with Protox isolated from corn etioplasts and for phytotoxic parameters of growth, chlorophyll content, and ethane evolution obtained with Scenedesmus acutus cells. Protox inhibitory activity of thiosemicarbazides was intermediate between that of thiadiazolidines and triazolidines. Phytotoxic parameters of thiosemicarbazides obtained from S. acutus cells were quite identical to those of triazolidines, although phytotoxic parameters of thiadiazolidines exhibited a slightly different pattern. Phytotoxic activities of 5-(4-bromophenyl)-3,4-tetramethylene-1,3,4-thiadiazolidin-2-one (thiadiazolidine 1) and 5-(4-chloro-2-fluoro-5-propargyloxyphenyl)-3,4-tetramethylene-1,3,4-thiadiazolidin-2-one (thiadiazolidine 4) were similar to those of the corresponding triazolidines, but phytotoxicities exhibited by 5-(4-(4-chlorobenzyloxy)phenyl)-3,4-tetramethylene-1,3,4-thiadiazolidin-2-one (thiadiazolidine 7) were 10 times less active with S. acutus than those of the corresponding triazolidine. Three thiosemicarbazides exhibited rapid conversion into triazolidines both in buffer at pH 7 (ca. 25–50%, 5 min incubation) and in Scenedesmus cultures (ca. 75%, 5 h incubation). Thiadiazolidines 1 and 4 were converted into corresponding triazolidines (ca. 70%) in S. acutus but were converted in buffer only in the presence of glutathione S-transferase plus ethylmercaptan, although thiadiazolidine 7 was not converted in the Scnedesmus culture. Apparently, the conversion step from thiadiazolidine to the thiosemicarbazide intermediate is enzymatic and the thiosemicarbazide intermediate to triazolidine is a spontaneous, nonenzymatic step.     

N'-硝基缩氨基胍类化合物对蚜虫的室内毒力测定及相关酶活性的影响

Su50[N'-硝基-1-异丙基-2-(4-硝基苯亚甲基)氨基胍]和Su56(N'-硝基-1-烯丙基-2-正丙基氨基胍)是利用活性亚结构拼接原理合成的具有新烟碱类和缩氨基脲类杀虫剂共同结构特征的硝基缩氨基胍类化合物。为了解Su50和Su56对蚜虫的生物活性及作用机理,采用叶片浸渍法测定了其对多种蚜虫的杀虫活性,用棉叶涂抹药液后接入棉蚜Aphis gossypii Glover测定了其对棉蚜的拒食活性,并采用生化方法测定了不同亚致死浓度(LC_(10)、LC_(25))Su56对棉蚜羧酸酯酶(CarE)、乙酰胆碱酯酶(AChE)、谷胱甘肽S-转移酶(GSTs)和多功能氧化酶(MFO)的酶活性的影响。结果表明:Su50和Su56对棉蚜A.gossypii/桃蚜Myzus persicae Sulzer,苹果黄蚜Aphis citricola van der Goot和梅大尾蚜Hyalopterus amygdali Blanchard均具有一定的杀虫活性,但毒力差异不显著,其中Su50对棉蚜、桃蚜、梅大尾蚜和苹果黄蚜的LC_(50)值分别为13.0、24.2、62.6和14.3mg/L,Su56的LC_(50)值则分别为30.3、30.2、101和3.23 mg/L;同时Su50和Su56对供试棉蚜均具有一定的拒食活性。生化试验结果表明,Su56在LC_(10)和LC_(25)浓度下对棉蚜的CarE、GSTs和MFO酶活性无显著影响,但在LC_(10)浓度下对棉蚜的ACNE酶活性却有显著抑制作用。     

Synthesis and acaricidal activity of phenylpiperazine derivatives

We synthesized 33 new phenylpiperazine derivatives and assessed their acaricidal activity. These derivatives were synthesized through sequential reactions consisting of the sulfonylation of 2-substituted 4-methylaniline with chlorosulfonic acid, reduction with red phosphorus and iodine, alkylation by alkyl halide, cyclization with bis(2-chloroethyl)amine hydrochloride, and N-substitution reaction of phenylpiperazines with various reagents. All phenylpiperazines synthesized were evaluated for acaricidal activity and their structure–activity relationships discussed, it was found that 4-substituted 1-[2-fluoro-4-methyl-5-(2,2,2-trifluoroethylsulfanyl)phenyl]piperazine derivatives exhibited good acaricidal activity. Among them, 1-[2-fluoro-4-methyl-5-(2,2,2-trifluoroethylsulfanyl)phenyl]-4-(trifluoromethylsulfonyl) piperazine showed the highest level of activity against Tetranychus urticae and provided a high level of activity against Tetranychus kanzawai and Panonychus citri. In addition, studies on the effect at various stages of T. urticae exhibited that this compound showed good activity against both adults and eggs.     

Comparison of kinetic properties of a hydrophilic form of acetylcholinesterase purified from strains susceptible and resistant to carbamate and organophosphorus insecticides of green rice leafhopper (Nephotettix cincticeps Uhler)

A hydrophilic form of acetylcholinesterase (AChE) was purified from N-methyl carbamate susceptible (SA) and highly N-methyl carbamate-resistant (N3D) strains of the green rice leafhopper (GRLH), Nephotettix cincticeps Uhler. Both of purified AChE from SA and N3D strains displayed the highest activities toward acetylthiocholine (ATCh) at pH 8.5. In the SA strain, the optimum concentrations for ATCh, propionylthiocholine (PTCh), and butyrylthiocholine (BTCh) were about 1 × 10⁻³, 2.5 × 10⁻³, and 1 × 10⁻³ M, respectively. However, in the N3D strain, substrate inhibition was not identified for ATCh, PTCh, and BTCh to 1 × 10⁻² M. The K_m value in the SA strain was 51.1, 39.1, and 41.6 μM and that in the N3D strain was 91.8, 88.1, and 85.2 μM for ATCh, PTCh, and BTCh, respectively. The K_m value in the N3D strain indicated about 1.80-, 2.25-, and 2.05-fold lower affinity than that of the SA strain for ATCh, PTCh, and BTCh, respectively. The V_max value in the SA strain was 70.2, 30.5, and 4.6 U/mg protein and that in the N3D strain was 123.0, 27.0, and 14.5 U/mg protein for ATCh, PTCh, and BTCh, respectively. The V_max value in the N3D strain was 1.75- and 3.15-fold higher for ATCh and BTCh than that in the N3D strain. However, it was 1.13-fold lower for PTCh. The increased activity of AChE in the N3D strain is due to the qualitatively modified enzyme with a higher catalytic efficiency. The bimolecular rate constant (k_i) for propoxur was 27.1 × 10⁴ and 0.51 × 10⁴ M⁻¹ min⁻¹ in the SA and N3D strain and that for monocrotophos was 0.031 × 10⁴ and 2.0 × 10⁴ M⁻¹ min⁻¹ in the SA and N3D strain. AChE from the N3D strain was 53-fold less sensitive than SA strain to inhibition by propoxur. In contrast, AChE from the N3D strain was 65-fold more sensitive to inhibition by monocrotophos than AChE from the SA strain. This indicated negatively correlated cross-insensitivity of AChE to propoxur and monocrotophos.     

Inhibition of two family 18 chitinases by various allosamidin derivatives

The inhibitory activities of several allosamidin derivatives on two family 18 chitinases, an insect enzyme from the epithelial cell line from Chironomus tentans, and a bacterial enzyme, chitinase A from Serratia marcescens, were evaluated. The following structural requirements are necessary for inhibition of the Chironomus enzyme: 1. One N-acetylallosamine residue can be omitted without impairment of enzyme inhibition. 2. At least one N-acetylallosamine sugar must be present. 3. Glucosamine can replace the allosamine moiety without a negative effect on the inhibitory activity. 4. The spatial arrangement of the allosamizoline moiety is important for inhibition. 5. If one sugar is omitted and the arrangement of the cyclitol residue is changed, the inhibitory effect is diminished further. For purified chitinase A from Serratia marcescens the arrangement of the aglycone moiety is equally important, but recognition of the sugar is different: 1. Omission of one allosamine residue decreases the inhibitory activity considerably. 2. Inhibition is improved if the remaining N-acetylallosamine is replaced by the epimer N-acetylglucosamine. Only endochitinase activity is affected, since chitin formation (up to 10^-4 M ) and N-acetylglucosaminidase activity (up to 10^-3 M ) are not impaired, at least in Chironomus cells. © 1998 SCI.     

含咪唑啉酮结构的吡唑类对羟基苯基丙酮酸双加氧酶抑制剂的除草活性及选择性研究

对羟基苯基丙酮酸双加氧酶（HPPD）是一种重要的除草剂作用靶标。为了发现具有高活性和高选择性的新型HPPD抑制型除草剂,对前期合成的23个含咪唑啉酮结构单元的吡唑类衍生物（2A~2W）进行了深入的生物活性评价和构效关系研究,比较了它们对拟南芥HPPD（AtHPPD）和人源HPPD（hHPPD）抑制活性的差异,从酶水平上总结了该类化合物的结构-活性关系和种属选择性规律,从活体植株水平研究了它们的除草活性。结果表明:部分化合物表现出良好的除草活性和作物安全性,其中化合物2E和2G在150 g/hm2剂量下对荠菜、繁缕、小藜和棒头草抑制活性达到80%以上,且其对作物的安全性也明显优于商品化除草剂硝磺草酮。此外,化合物2P在酶水平上的选择性倍数高达93倍,展示出良好的应用潜力。     

N-取代苯基-2-(苯并异噻唑啉-3-酮-2-基)甲酰胺的合成及抑菌活性

通过取代苯异氰酸酯与1,2-苯并异噻唑啉-2(3H)-酮(BIT)反应,制备了13个2-(苯并异噻唑啉-3-酮-2-基)甲酰胺类化合物,其中9个未见文献报道。所有化合物的结构均经IR、1H NMR和元素分析确认。初步的抑菌活性测定结果表明,部分目标化合物对供试病原菌具有很好的抑菌活性,尤其对于枯草芽孢杆菌Bacillus subtilis和芒果蒂腐病菌Botryodiplodia theobromae,大部分化合物在50 mg/L下的抑制率在80%~100%之间。     

吡唑酰胺基脲类化合物的合成及除草活性

根据活性结构拼接原理,以1-甲基-3-乙基-5-吡唑甲酰肼为起始原料,设计合成了19个新吡唑酰胺基脲类衍生物,其结构均经过核磁共振氢谱、红外光谱、质谱和元素分析确证。生物活性测试结果表明:大部分化合物对双子叶杂草苘麻Abutilon theophrasti、反枝苋Amaranthus retroflexus以及凹头苋A.ascedense显示出较好的除草活性及选择性,如在2 250 g/hm2的剂量下,3i在苗后和苗前处理时,对苘麻和反枝苋的抑制率都达到了100%。复筛的结果表明,在375 g/hm2下,3i对双子叶杂草表现出中等除草活性。     

Design, semisynthesis and insecticidal activity of novel podophyllotoxin derivatives against Brontispa longissima in vivo

In an attempt to find the effective phytopesticides, a series of novel podophyllotoxin derivatives were firstly synthesized and preliminarily tested for their antifeedant and insecticidal effects against the fifth-instar larvae of Brontispa longissima. The different antifeedant and insecticidal activity ranges of compounds 3a-l showed that variations of NR₁R₂ groups in the 4-position of podophyllotoxin skeleton markedly affected the activity profiles of this compound class, and some important SAR information has been revealed from it. To clarify their mode of action of insecticidal activity, the docking models as well as tubulin inhibitory effect of representative compound 3i were also investigated, and the result indicated that the insecticidal activity of these compounds was due to the tubulin inhibitory effect of these derivatives, thereby possibly providing some useful information for rational designs of novel podophyllotoxin-based insecticides.     

Synthesis and insecticidal/acaricidal activity of novel 3‐(2,4,6‐trisubstituted phenyl)uracil derivatives

A series of novel 3‐(2,4,6‐trisubstituted phenyl)uracil derivatives has been synthesised and assayed for insecticidal/acaricidal activity. The assay indicated certain requirements for optimal insecticidal activity, which can be summarised as follows: (a) the substituents on the phenyl ring should possess hydrophobicity and electron‐withdrawing properties, and the sum of their volumes determines the level of activity; (b) the substituent at the 6‐position on the uracil ring should also possess electron‐withdrawing properties and hydrophobicity, together with the correct volume; (c) the 1‐position on the uracil ring should be unsubstituted for activity against Nephotettix cincticeps and Epilachna vigintioctopunctata, but substituents with length C3 to C4 may be optimal for activity against Tetranychus urticae; (d) certain substituents at the 5‐position of the uracil ring give activity against E vigintioctopunctata and T urticae, but not against N cincticeps; (e) a thiocarbonyl group at the 2‐position of the uracil ring is less effective than a carbonyl group. Of the compounds assayed, 3‐(2,6‐dichloro‐4‐trifluoromethylphenyl)‐6‐trifluoromethyluracil showed high activity against all the species assayed. © 2000 Society of Chemical Industry     

Structural Effects of N-Arylcarbamoylpyrazolines on Calcium Uptake in Rat Brain Synaptosomes

N-Arylcarbamoylpyrazolines with various substituents at the para position of the carbamoyl benzene ring inhibited ATP-dependent Ca²⁺-uptake in synaptosomes prepared from the rat brain. The activity of these compounds was evaluated as log(1/I₅₀), the reciprocal logarithm of half inhibitory concentration, I₅₀ (m ), from the concentration–response curve for the inhibition of Ca²⁺-uptake. Among the compounds tested, methyl 3-(4-chlorophenyl)-4-methyl-1-[N-(4-trifluoromethylphenyl)carbamoyl]-2-pyrazoline-4-carboxylate was the most potent, the I₅₀ value of which as 9·12×10⁻⁷ m . Variations in the activity in terms of log(1/I₅₀) were quantitatively analysed using a substituent parameter, showing that the higher the electron-withdrawing effect of the substituent, the higher was the activity. The substituent effects were similar to those on insecticidal activity against the Americal cockroach. The higher the inhibitory activity against Ca²⁺ uptake, the higher seemed to be the insecticidal activity. Methyl(4S) - 3 - (4 - chlorophenyl) - 4 - methyl - 1 - [N - (4 - chlorophenyl)carbamoyl] - 2 - pyrazoline -4-carboxylate had higher inhibitory activity against Ca²⁺-uptake and higher in-secticidal activity than the R-isomer, but the difference was greater in theCa²⁺-uptake system.     

Synthesis and insecticidal activity of novel 1,3,4-oxadiazolin-5-one and pyrazolin-5-one derivatives

A series of novel 2-(2,4,6-trisubstituted phenyl)-1,3,4-oxadiazolin-5-one derivatives and 3-(2,4,6-trichlorophenyl)pyrazolin-5-one derivatives were synthesized and evaluated for insecticidal activity. It was found that a moderately bulky alkyl group, such as a tert-butyl group, on the heterocyclic ring, and a trifluoromethyl group on the benzene ring were optimal substituents on the molecule. The oxygen atom in the oxadiazoline ring was essential for insecticidal activity. Of the compounds assayed, 4-tert-butyl-2-(2,6-dichloro-4-trifluoromethylphenyl)-1,3,4-oxadiazolin-5-one gave the highest activity against Nephtotettix cincticeps, with an LC₅₀ value of 0.51 mg litre⁻¹. © 1999 Society of Chemical Industry     

Increased activity associated with reduced sensitivity of acetylcholinesterase in organophosphate-resistant greenbug,schizaphis graminum (homoptera: aphididae)

The activity and sensitivity of acetylcholinesterase (AChE, EC 1.1.1.7) from an organophosphate-susceptible (OSS) and three resistant (OR-0, OR-1 and OR-2) strains of the greenbug (Schizaphis graminum) were biochemically compared. All three resistant strains displayed higher frequencies of individuals with respect to both increased activity of AChE toward the model substrate acetylthiocholine (ATC) and reduced sensitivity of AChE to inhibition by paraoxon as compared with the OSS strain. Kinetic study indicated that AChE from the OR-0, OR-1 and OR-2 strains had 3.3-, 2.7- and 2.3-fold, respectively, lower affinity, but 1.5-, 2.2- and 2.0-fold, respectively, higher catalytic activity toward ATC than AChE from the OSS strain. Significantly increased activity of AChE in the resistant strains was also confirmed by non-denaturing polyacrylamide gel electrophoresis, and appeared to be associated with the increase of general esterase activity. Inhibition kinetics revealed that AChE from the OR-0, OR-1 and OR-2 strains was 2.1-, 2.2- and 2.7-fold less sensitive to inhibition by paraoxon than that from the OSS strain. The study suggested that both qualitative and quantitative modifications of AChE had evolved in the resistant strains and were likely to significantly enhance the overall resistance level in greenbugs. © 1999 Society of Chemical Industry     

Photolysis of dichlofluanid

Dichlofluanid was found to be degraded by ultraviolet light in methanol, benzene and acetone solution. The products from acetone solution included N,N-dimethyl-N′-phenylsulphamide, phenyl isocyanate, phenyl isothiocyanate and dimethylamidosulphonyl chloride. G.c.-m.s. studies further indicated the presence of bis(dichlorofluoromethyl) disulphide, 1-(dichlorofluoromethylthio)propan-2-one and 1-(dichlorofluoromethylsulphonyl)propan-2-one. In-vitro tests against Botrytis cinerea showed that irradiation decreased the activity of dichlofluanid and that synergism did not occur.     

新型含2(1H)-喹啉酮的甲氧基丙烯酸酯类

以(E)-2-[2'-(bromo-methyl)phenyl]3-甲氧基丙烯酸甲酯和2(1H)-喹啉酮类化合物为原料,通过醚化等反应,合成了11个新型含2(1H)-喹啉酮结构的甲氧基丙烯酸酯类化合物,其结构经红外、电喷雾串联质谱(ESI-MS)和核磁共振氢谱确证。初步生物活性测试结果表明:在100 mg/L质量浓度下,部分目标化合物对烟草赤星病菌Alternaria alternata等6种病原菌具有一定的抑菌活性,其中5a对水稻稻瘟病菌Pyricularia grisea的抑菌率达100%。