PROCESS FOR ENHANCING THE ACTIVITY OF PLANT PROTECTING AGENTS BY USING CYCLODEXTRIN

Abstract: Fungicidal plant protecting composition comprising 3-90% by weight of a fungicidal active ingredient in admixture with 1-90% by weight of cyclodextrin and optionally with usual auxiliary agents. The advantage of the synergistic composition of the present invention is that identical fungicidal effect can be achieved with a significantly lower active ingredient dosage and this decreases the costs involved with the active ingredient and reduces the risks of environmental pollution as well.

Description: PROCESS FOR ENHANCING THE ACTIVITY OF PLANT PROTECT¬ ING- AGENTS BY USING CYCLODEXTRIN Technical field This in ention, relates to new and improved plant protecting agents, particularly fungicidal compo¬ sitions and a method for the use thereof. Background art Recently several articles and patents have been published relating to the use of cyclodextrin in plant protecting formulations [Novenyvedelem, 19 r . 36 (1983); J. Szejtli: Cyclodextrins and their In¬ clusion Complexes, Akademiai Kiadό , Budapest, 1982], On forming complexes of molinat (S-ethyl-N,N-hexa- methylene-thiocarbamate) , bentiocarb (S- -chloro- benzyl-diethylthio carbamate) and dichlorphos (2,2- -dichlorovinyl-dimethyl-phosphate ) the volatility of the active ingredient is significantly decreased and the activity of the pesticide remains maintained for a longer period of time [Mikasa Chemical Industrial Co. ; KOKAI No. 80.81806; DOS No. 2, 2,3l6 (197*0; Acta Chem . Acad . Sci . Hung. 107 , 195 ( l98 l ) ] . Methyl- -parathion ( 0 , 0-dimethyl-0- --nitrc phenyl-phosphoro- thioate ) and natural pyrethrines and pyrethro ides , respect ive ly, are converted into the cyc lodextrin A 3 73/77-OE complexes in order to increase the stability against light and oxygen to a considerable extent [Pestic. Sci. 1_1, 13^ (198O); US patent No. 3,8^6,551 (197*0; Nippon Noyaku Gakkais i !_, kl (1976); 2_, l (1977)]. The dichlobenyl (2,6-di- chloro-benzonitrile) active ingredient easily sub¬ limates and on standing the granulated product sticks together; this can be inhibited by forming complex -with cyclodextrin [5th Int. Cong. Pesticide Chem. (TUP C) Kyoto (1983)]. The complex format ion of 2-chloromethane- -phosphonic acid with cyclodextrin results in the fact that on contacting with plant t issue the ethylene release is a long-lasting process and this is more eff icient than the de livery of ethylene from a very prompt ly acting active ingredient [Acta Chim. Acad . Sci . Hung. 107 , ≥31 ( 1981 ) ] . Disclosure of the invention It was not aforeseen on the basis of prior art that cyclodextrin would synergize the efficiency of fun¬ gicides . The object of the present invention is to provide fungicidal compositions comprising cyclo¬ dextrin in which cyclodextrin synergizes the acti¬ vity of known fungicidal active ingredients to a significant extent. Thus identical fungicidal active ingredient dosage results in a higher acti¬ vity or the same fungicidal effect can be achieved by using a lower dose of the active ingredient and this is a- considerable advantage from the point of view of both economy and the safety of environment. According to an aspect of the px'esent in¬ vention there is provided a fungicidal plant pro¬ tecting composition comprising 3-90 by weight of a fungicidal active ingredient in admixture with 1 - 90 by weight^ of cyclodextrin and optionally th usual auxiliary agents. In the fungicidal composition according- to the present invention the ratio of the fungici- dal active ingredient and cyclodextrin amounts to 90:1 - 1:5, preferably 2-5:1. The composition according to the present invention may preferably comprise the following fungicidal active ingredients: benomyl = l-butylcarbamoyl-benzimidazole-2- -methyl-carbamate • BCM = 2-carbomethoxyamino-benzimidazole ; mefcomeclan = l-(3 , 5-dichlorophenyl) -3-methoxy- methyl-pyrrolidine-2 , 5-dione ; phenarimol = 2 , ' -dichloro-cc-( pyrimidine-5-y l)- -diphenyl- ethanol. As cyclodextrin cc-, β- and/or y-cyclo- _ - dextrin may be used. According to a preferably embodiment of the present invention the ratio of the above ac¬ tive ingredients and cyclodextrin may be as fol- lows : benomyl : cyclodextrin = 2-5:1 BCM : cyclodextrin = 2-5:1 metomeclan : cyclodextrins 2-20:1 phenarimol : cyclodextrin= 1-100:10. According to a further aspect of the present invention there is provided a fungicidal method of treatment which comprises applying onto the plants or the other surface to be treated a composition according to the present invention, preferably at a rate of 0.5-6 kg/ha, particular¬ The present invention is based on the re¬ cognition that known fungicidal active ingredients and cyclodextrin exhibit a synergistic effect which is a result of one or two of the following factors: - the own fungista ical activity of cyclodextrins ; - the solubility increasing effect of cyclodextrins. The fungistatical activity of cyclodex¬ trins has never been disclosed in prior art. The said activity may be proved by the following test: Agar nutrient media comprising 0.1 - 0.2 - 0.5 - 1.0 - 2.0 - 5.0 - 10.0 - 20.0 - 100.0 - 200.0 - -00.0 - 800.0 - 1200.0 - 1500.0 - 2000.0 - 3000.0 Ug β-cyc lodextr in/ml , respectively, are prepared in Petri-dishes . Mycelium discs are cut out from surface cultures of three test fungi and are placed onto the agar nutrient media in the Petri-dishes. Incubation is carried out in a ther¬ mos tate whereupon the increase of the diameter of the colonies is determined and compared to that of the control. The morphology of the colonies and the diffusion of the dye-substance produced by the fungi into the nutrient medium are evaluated as well. The results are summarized in Table 1. Table 1 Fu gis atical effect of β-cyclodextrin Concentration Inhibition "o M i c r o o r a n x s m s Rhizoctonia Sclerotinia Alterna- solani sclerotiorum ria tenuis 3000 19 16 1500 17 Wk 12 00 6 12 10 200 3 12 7 In a dose range of 0.1 - 20 /ug/ml the effect of β-cyclodextrin is of a qualitative character. The fungistatical effect of cyclodex¬ trin manifests itself in the changed morphology, structure and colour of the colonies and in the amount of the dyes uff penetrated into the nutri¬ ent medium. However at higher dose range the effect of cyclodextrin is already of a quantitative nature, thus the decrease of the diameter of the colonies can be measured and the amount of the biomass form¬ ed is reduced to a rate which can be evaluated (Table l) . A study of the surfacial cultures show that β-cyclodextrin inhibits the formation of the propagative organs. The main feature of the solubility increas¬ ing effect of cyclodextrin due to the formation of inclusion complexes resides in the fact that in aqueous solution beside the molecularly dispersed (i.e. actually dissolved) active ingredient and the mycelia consisting of some or a lot of molecules (microcrystal, microdrop), the cyclodextrin-active ingredient inclusion complex being also in mole¬ cularly dispersed form appears, too. Since the said system is characterized by o an unusually dynqmical equilibrium (within 10~ sec " the active ingredient incorporated into the inclusion complex acts in the same way from the point of view of absorption as the free dissolved active ingredient. Thus the concentration of molecularly dis¬ persed molecules being suitable for direct absorp- tion may be significantly increased with the aid of cyclodextrins and this accelerates the rate of ab¬ sorption, i.e. the same efficiency can be achieved by using a lower active ingredient dose. The positive effect of cyclodextrine on the solubility of active ingredients is shown on the example of benomyl. The said active ingredient ( l-butylcarbamoyl-benzimidazole-2-methyl-carbamate) is a systemic fungicide, which is poorly soluble in water and when dissolved in water rapidly de- composes to me.thy 1-benzimidazole carbamate having also a fungicidal effect but being still less soluble in water. On shaking benomyl and benomyl+cyclodextrin, respectively, in water at 25 C the solubility data summarized in Table 2 are obtained. (Benomyl and benomyl + β-cyclodextrin, respectively, are shaken o in water at 25 C, the samples are filtered and the dissolved benomyl contents of the filtrates are determined by UV spectrophotometry ) . Table 2 Increase of the solubility of benomyl under the effect of β-cyclodextrin Time of Amount of dissolved benomyl experiment (minutes ) Weighed in: 1000 Ug/rnl Weighed in: 170 ,ug of benomyl + of benomyl 830 ,ug/ml of β-CD 10 2 0,2 7 CO 1 20 3 0.3 9 5.3 ho .5 0. 5 10 5.9 80 5 0.5 12 7.0 120 5 0.5 13 7. Weighed in: 5000 /ug/ml Weighed in: 850 ,ug of beno¬ of benomyl myl + 4150 ug/ml β-CD - 9 - Benomyl is put on the market under the commercial name Fundazol 50 WP; benomyl active ingredient content: 50 Jo . In Table 3 the solubility • data of benomyl, a mixture of benomyl and cyclodex- trin, Fundazol 50 WP, and a mixture of Fundazol 50 WP and cyclodextrin are shown. In each experiment 3000 /ug/ml of the test substance are weighed in and shaken at 25 'C. Benomyl is a 100 o active ingredient; the benomyl content of the benomyl/ cyclodextrin mixture amounts to 17•3 ?° ; the beno¬ myl content of Fundazol 50 WP is 50 o; the benomyl content of the mixture of Fundazol 50 WP and cyclo¬ dextrin amounts to 8 ° ,6 fo . It appears from Table ' 3 that as a result of the formulation the solubility of benomyl is increased four times . Cyclodextrin per se causes a further 1.5-2-fold increase of the solubility of both original benomyl and formulated Fundazol 50 WP. Taking into considera ion that in the mixtures comprising cyclodextrin the amount of benomyl active ingredient is considerably lower and at the same time in aqueous solution the concentration of benomyl being responsible for the actual biologi¬ cal effect ..became significantly higher, it was aforeseen that this had to be manifested in the biological effect, too. - Li ¬ The solubility of benomyl from various materials comprising benomyl was determined by shaking in water at 25 C. 2000 /ug/ml of solid material are weighed in which corresponds to the following amounts of benomyl: in the case of benomyl: 2000 ug/ml in the case of benomyl + β-C in the case of Fundazol 50 WP: 1000 /Ug/ml in the case of Fundazol 50 WP + β-CD: 175 /Ug/ml + The following tests substantiate the surprising synergism between known fungicides and β-cyclodextrin. Stable, highly dispersed aqueous suspensions of the test materials are added to agar nutrient media in the desired concentration (O.l - 200 /ug/ml), whereupon the nutrient media are poured into Petri-dishes. Mycelium discs are cut out from the surfacial cultures of the test fungi and the discs are placed into the Petri- -dishes containing the test materials. Incubation is carried out in thermostate whereupon the in¬ crease of the diameter of the colonies is measured and and compared to that of the control. The tests are carried out in three replicates. In Table 4 the effect of the fungicide Fundazol 50 WP (benomyl content 50 o) and a mix¬ ture of Fundazol 50 WP + 10 of β-cyclodextrin is disclosed. The results clearly prove the synergistic activity of β-cyclodextrin; the in- creased activity is particularly significant against Botrytis cinerea and Monilia fructigena. Table 4 F ingicid act iv ity of Fundazol and recrystallizod β-cyclodextrin Microorganism ED related t Increase of 50 ( ug/ml, to active ingredien activity (x) Fund z l Fundazol + 10 β-CD Rhizoctonia solani 0.87 0.64 1.3 Sclorotinia sclerotiorum 0.12 0-05 2.4 Fusarium * oniliforme 0.88 0.38 2.3 I Botxytis cinerea 0.l4 0.0125 10.2 Ascυchyta pisi 0.72 0.25 2.9 Fusarium culmorum 0.77 0.44 1.7 Colletotrichum lini 0.68 0.5 1.3 Monilia fructigena 0.05 0.0125 4.0 - 15 - Metomeclan is a contact fungicide in¬ soluble in water [ l-( 3 > 5-dichlorophenyl) -3-me- thoxyraethyl-pyrrolidine- ,5-dione] . The activity of metomeclan is significantly increased by the addition of cyclodextrin. In Table 5 the fungici¬ dal effect of metomeclan and a mixture of meto¬ meclan + 10 o of β-CD is set forth. Table 5 Increase of activity of metomeclan by adding 10 % of β-cyclodextrin Test microorganism ED ( ,ug/ml, related to active ingredient Increase of activity (x) Metomeclan Metomeclan + 10 % of β-CD Fusarium monilifoπne 12 7 1.7 Alternaria tennis 2.9 1.8 1.6 Steinphylium radicinum 5-7 3.9 1.5 1 Rhizoctonia solani 3-3 2.3 1.4 y Colletotrichum lini 25-5 8.9 2.9 1 Ascochyta pisi 4.6 2.8 1.6 Fusa ium culmorum 16.5 7.5 2.2 Alternaria crassa 3.9 p 1.8 In vivo tests are carried out on wheat-powdery mildew (host-parasite) by using a combination of phenarimol [2 ,4 ' -dichloro-ce- -(pyrimidine-5-yl)-diphenyl-ethanol] and β-cyclo- dextrin. The tests are carried out in three repli¬ cates in phytotrone under usual experimental sys¬ tem and environmental conditions (20 C, humidity 90 %, light intensity 9000 lux. ) In culturing dishes (diameter 11 cm) as average l6θ plants (5-6 cm stage) are treated with 8 ill of stable aqueous suspensions comprising the test material. The res xlts are summarized in Table 6. The inhi¬ bition activity is calculated on the basis of the Hinfner-Papp formula by using the infectedness index. _ T___a___b_l___e______ 6_ In vivo tost of phonarimol + β-cyclodextrin on iirheat powdery mildew host parazite Phonarimol I n i b i t i o n a c t i v i t y Jo concentration ug/m,1 Phenari ol Phenarimol + β-CD (ratio 1:5) 10 100.0 100.0 5 99.4 100.0 , 2.5 87.2 98.2 a 1.25 73-5 83-2 O.625 29.4 42.3 In a further series of experiments it is tested whether known linear dextrins obtained by thermal, enzymatic or acidic decomposition of starch exhibit similar effects as cyclodextrins. The said tests show unambiguously that only cyclo¬ dextrins possess the above fungicidal-synergizing activity. Industrial applicability As a result of the synergizing effect of cyclodex¬ trins the dosage of known and generally used fungi¬ cidal active ingredients can be signi icantly de¬ creased under achieving identical or even increased fungicidal effect and this decreases the costs in¬ volved with the active ingredients and reduces the risks of environmental pollution as well. Modes of Carrying out the Invention Further details of the present invention are to .be found in the following Examples without limiting the scope of protection to the said Examples. Example 1 Spray compr is ing benomyl as act ive in- red ient Benomyl is put on the market as spray in the form of a wettable powder having an active ingredient content of 50 fo under the commercial name Fundazol 50 WP. A product having the same ac- tivity but containing a smaller amount of active ingredient is prepared as follows: 35 kg of benomyl pre-micronized in an air-flow mill and 15 kg of crystalline β-cyclo-- dextrin (moisture content 13 fo ) also pre-micronized in an air-flow mill are admixed with 4θ kg of pre¬ cipitated calcium carbonate, 5 kg of sulfide waste p'owder and 5 kg of an anionic tenside containing 50 fo of water (preferably Genapol PGM, pre-heated to 50 C) in a homogenizer. The homogenized mate- rial is dried, micronized in order to separate the particles stocked together and finally packed. Example 2 One proceeds according to Example 1 i.e. the components are micronized, homogenized, dried and re-micronized . The composition is as follows: Benomyl (related to 100 fo active ingredient ) 4o kg Precipitated calcium carbonate 4o kg Tensiofix BC 2 2. 5 kg Totamine 5 kg β-Cyclodextrin 12 - 5 kg Example 3 Seed-treating composition comprising benomyl as active ingredient One proceeds according to Example 1. The composition is as follows: Benomyl 35 kg Diot ilan 1 kg Evidet 27 1 kg Tylose N 20 1 kg Aerosil "300" 0. 5 kg Safranin P extra 2 kg Spray-dried crude converted cyclo- dextrin mixture (β-cyclodextrin content about 48 fo; cc- and y -cyclo- dextrin content 2 fo , partially de¬ composed starch content about 50 f) 38 kg Precipitated calcium carbonate 21.5 kg Example 4 Seed-treating composition comprising Abem (2-ca,rbomethoxyaminobenzi_nidazole ) as active ingredient The Abem active ingredient is dissolved in hydrochloric acid under heating, whereupon it is neutralized with an emulsion consisting of a mixture of ammonium hydroxide, paraffine oil and β-cyclodextrine- The suspension is stabilized with tens ides in a manner known per se. The seed-treat- - 22 - ing agent has the following composition: Para fine oil 19-8 fo β-cyclodextrin oi Ethylene glycole 5.6 1° Ammonium chloride (formed on neutra¬ lizing the hydrochloric acid solu¬ tion) about 10 f° Various tens ides: Emulsogen M 0.24 fo Atlox 4868 B 1.6 fo Triton X 5 1.9 fo Tensiofix L 051 0.2 fo Tensiofix 821 0.2 fo filled up with water to 100 fo

Claims: What we claim is, 1. Fungicidal plant protecting composi¬ tion comprising 3-90 fo by weight of a fungicidal active ingredient in admixture with 1-90 fo by weight of cyclodextrin and optionally with usual auxiliary agents. 2. Fungicidal composition according to Claim 1 comprising the fungicidal active ingredient and the cyclodextrin in a ratio of 90:1 - 1:5, pre¬ ferably 2-5:1. 3. Fungicidal Composition according to Claim 1 comprising benomyl, BCM, metomeclan or phenarimol as fungicidal active ingredient. 4. Fungicidal composition according to Claim 1 comprising cc- , β- or y * -cyclodextrin as cyclodextrin. 5. Fungicidal composition according to any of Claims 1-4 comprising benomyl and cyclo- dextrin in a ratio of 2-5:1, preferably 3.5:1.5- 6. Fungicidal composition according to any of Claims 1-4 comprising BCM and cyclodextrin in a ratio of 2-5:1, preferably 3:1. 7. Fungicidal composition according to any of Claims 1-4 comprising metomeclan and cyclo¬ dextrin in a ratio of 2-20:1, preferably 10:1. 8. Fungicidal composition according to - 24 - any of Claims 1-4 comprising phenarimol and cyclo¬ dextrin in a ratio of 1-100:10, preferably 1:5. 9- Fungicidal method of treatment which comprises treating the plant or other surface to be treated with a plant protecting composition according to Claim 1, preferably at a rate of 1.2-1.6 kg/ha.

Inventors: BANKYNE ELOED ERZSEBET, BERNATH JENOE, DOBOS EVA, KINICZKY MARTA, SZEJTLI JOZSEF, TETENYI PETER, TETENYINE ERDOESI MAGDA, BANKYNE ELOED, ERZSEBET, BERNATH, JENOE, DOBOS, EVA, KINICZKY, MARTA, SZEJTLI, JOZSEF, TETENYI, PETER, TETENYINE ERDOESI, MAGDA
Applicants: CHINOIN GYOGYSZER ES VEGYESZET, CHINOIN GYOGYSZER ES VEGYESZETI TERMEKEK GYARA RT
Application year: 1986
Main classification: A01N43
IPC codes: A01N25, A01N43, A01N47, A01N63