BIOCIDAL-ANTIFOULING AGENTS WITH LOW ECOTOXICITY INDEX

Abstract: A use of vitamin derivatives as biocidal and antifouling agents for preventing and slowing the growth of algae, molds and microorganisms. In particular, the vitamin derivatives are constituted by menadione, its salts and derivatives with the heterocyclic bases trazine and piperazine and menadione epoxide.

Description: BIOCIDAL-ANTIFOULING AGENTS WITH LOW ECOTOXICITY INDEX Technical Field The present invention relates to biocidal-antifouling agents with low ecotoxicity index. Background art In particular, the present invention relates to the use of selected vitamin derivatives as biocidal and antifouling agents for preventing and slowing the growth of algae, molds and microorganisms. Menadione and its derivatives are notoriously vitamin derivatives which have an antihemorrhagic activity and have long been used in the medical and veterinary field. In particular, adducts of menadione bisulfite with heterocycles such as triazine, pyrimidine, guanidine have been described in US-3,328,168, while adducts of menadione bisulfite with pyridine derivatives are known from Italian Patent No. 1,097,391. Up to now, the only indication for use of these menadione adducts has been their antihemorrhagic activity. Accordingly, these compounds have been applied in the veterinary field as medicines and as additives for feeds meant for farm animals and fish. Surprising, it has now been found that there is another unexpected indication for use of menadione and its derivatives in a technical field which is entirely different from the one in which they are currently and commonly used. Specifically, it has now been found surprisingly that these compounds have a great ability to inhibit and slow the deposition and growth of a layer of living organisms such as a layer of vegetation, mold or microorganisms on the surfaces of objects and structures exposed to humidity or immersed in fresh or salt water. Disclosure of the Invention One of the aims of the present invention is to provide new indications for use for a class of compounds correlated to the menadione molecule. Another object is to provide biocidal and antifouling agents which are highly effective in preventing the adhesion of algae, molds and colonies of microorganisms on surfaces of objects and structures exposed to humidity or immersed in water. Another object is to provide a class of compounds having a biocidal and/or antifouling activity which have minimal ecotoxicity and polluting activity and can therefore be used in the ecosystem without compromising its balance. In view of this aim, these objects and others which will become apparent hereinafter, and in accordance with a first aspect of the present invention, use of menadione and its derivatives as biocidal and/or antifouling agent is provided. Within the scope of the present invention, the term "menadione derivatives" includes menadione (2-methyl-l,4-naphthoquinone), menadione bisulfite (MSB) and its derivatives with the heterocyclic bases triazine and piperazine. Preferred derivatives or compounds are selected from the group comprising menadione triaminotriazine bisulfite(I), menadione(bis) piperazine bisulfite(II), menadione dimethylpyrimidinol bisulfite (MPB), menadione bisulfite nicotinamide salt or salt with nicotinic acid, menadione triaminotriazine particularly as bisulfite salt, menadione epoxide, particularly 2-methyl-2,3-epoxy-l,4-naphthalene-dione(III) and their salts or esters. Further menadione derivatives that can be used within the scope of the invention are exemplified in US-2,367,302 and US-3,328,169. The compounds according to the present invention (menadione and its derivatives) are used as antifouling and biocidal agents having low ecotoxicity and minimal polluting activity with respect to the ecosystem. The compounds according to the invention are used whenever materials, objects and structures need to be protected from the growth of vegetation or colonies of unwanted microorganisms. In particular, the compounds according to the invention are suitable to prevent and limit the growth of algae and molds on the surfaces of objects that make contact with water or with ambient moisture for prolonged periods of time. In particular, these objects and structures include watercraft hulls, submerged masonry or metallic structures, floating transport or signaling means, fishing nets, and cooling systems which use seawater. The materials that can be treated with the compounds according to the invention are materials of various origin, commonly used in the manufacture of items which make contact with fresh water or salt water, such as for example steel, concrete, glass, plastics, rubber, wood, textile fibers, leather, et cetera. The use according to the present invention advantageously provides for the addition or application of an amount which is effective from an antifouling and/or biocidal standpoint of a compound of the above described type to a material or structure exposed to water or moisture. The compounds according to the invention are also suitable in the prevention and slowing of mold growth. For this use, the compounds according to the invention are advantageously added to water-based emulsion paints, to adhesives, cellulose-based glues, fluids for machining and cooling metals, lubricating fluids for spools of thread, systems and raw materials for the processing of paper and for the preservation of tanned hides. It has also been found surprisingly that the menadione derivatives according to the invention have a biocidal activity against the most disparate bacterial strains that form colonies on the above cited objects and structures. The compounds of the invention are used in amounts which vary according to the type of application and can be easily determined by a person skilled in the field. Suitable concentrations for the use of the invention can vary from a few ppm (0.0001% by weight for use as antifouling in cooling water such as in power stations, steelworks) up to concentrations of 40%, by weight (formulation for antifouling paints). An effective biocidal concentration for menadione and derivatives thereof is advantageously in the range of 0.5% to 10% by weight, preferably of 1 to 5% by weight. The compounds according to the invention can be applied pure or added to carriers, such as powders, nebulizing agents and dispersants, or can be dissolved or suspended in a liquid, and in this case they are usually accompanied by wetting agents or emulsifiers in order to promote uniform dispersion of the active principle. In the case of use of menadione adducts as mold preventers for fluids such as lubricants used in the machining of metals or lubricants for spools of thread, cellulose-based adhesives, for example wallpaper, said adducts can be used in suspension or emulsion, associated with wetting agents or emulsifiers, preferably at concentrations between 3 and 15% by weight. The compounds according to the invention are furthermore used in the preparation of formulations of antifouling paints preferably in amounts which can vary between 3 and 15% by weight, advantageously in association with base materials. The base materials for antifouling paints include binding agents such as synthetic and natural resins, homo- and copolymers, synthetic and natural caoutchouc, acrylic polyurethane epoxy resins or preparations of monomers to be polymerized in place to which the antifouling agent is added. The use of menadione and derivatives according to the invention allows to considerably limit the problems of pollution and ecotoxicity caused by the use, in marine paints, of antifouling agents which are usually based on heavy metal derivatives. The compounds according to the invention have proved themselves highly toxic and repellent both against microorganisms which tend to form colonies and against algae and molds. Differently from commonly used antifouling agents, which are based on heavy metals, the derivatives according to the invention, by having a common non-toxic vitamin matrix, are not a source of pollution for the environment. This advantage is more evident when the compounds according to the invention are used in the cooling of industrial plants located in coastal regions, since in this case enormous amounts of water are treated with antifouling agents in order to avoid the growth of algae in the pumping piping. The high antifouling effectiveness achieved at low dosage, together with the high biodegradability of the compounds according to the invention, can be noted in the low values of the EII (Environmental Impact Index) = 1- EC SQ fL 1 (menadione triaminotriazine bisulfite = -1.84; menadione piperazine bisulfite = -2,0; menadione epoxide = -3.0), where: EC 50 is the concentration that inhibits by 50% the settling of the species of larva used as target; LCI is the minimum toxic concentration for the larvae used as target. The lower the ratio between the two parameters, the less the product pollutes. Otherwise, higher values correspond to a higher likelihood of damaging the ecosystem in which the compound is active. This index is an empirical value for giving a measurement of the toxicity of the tested components with respect to other organisms and also provides an index of polluting characteristics. By subtracting this ratio E Q /L from 1, the EII has a positive or negative value depending on whether antifouling effectiveness (EC 50 ) becomes apparent before or after the minimum toxic concentration (L ). Clearly, products having EII values which are positive or in any case negative but close to zero are to be preferred over those which have negative EII values. The following examples are provided merely as illustration of the present invention and must not be intended as limiting the scope thereof as defined in the appended claims. EXAMPLE 1 The antifouling and biocidal activity of the three following menadione derivatives, menadione triaminotriazine bisulfite, menadione bisulfite (piperazine-bis), 2,3 epoxy-2-methyl-l,4-naphthoquinone, was tested in the laboratory by adopting the following method, which is extensively described in the document "Evaluation of antifouling biocide performance by means of laboratory test", by Sebastiano Geraci and Marco Faimali, Istituto per la corrosione marina dei metalli, CNR, Genoa). MICROORGANISM USED Approximately 700 adults of Balanus amphitrite were removed and acclimatized in the laboratory in 500-ml containers which were highly oxygenated and then kept in a chamber set by thermostats to 20°C with a light/darkness photoperiod of 12:12 hours for 3 weeks, supplying them every 48 hours with juvenile stages of Artemia salina and two species of microalgae: Tetraselmis suecica and Paclova luther i. After the acclimatization period, the adult culture yielded on a weekly bases a significant production of larvae required for the test. PREPARATION OF THE SOLUTIONS Seawater was used as solvent. Stock solutions were prepared to obtain the following concentrations for the tests: 0.01; 0.1; 0.2; 0.4; 0.6; 0.8; 1; 2; 4; 6; 8; 10; 100 microg per ml "1 . ACUTE TOXICITY TEST The resulting larvae were separated from the adults immediately after emission and divided into 200-ml beakers with natural seawater filtered at 0.22 microns and a concentration of 5xl0 "5 cells/ml of Tetraselmis seucica, keeping them for 24 hours in a thermostat-controlled cabinet at 20° C. Then approximately 200-250 nauplii were placed in Petri dishes with 10 ml of final volume of natural seawater filtered at 0.22 microns and the portion of each one of the three above cited derivative, in order to obtain the various concentrations of the test. All concentrations were tested 4 times for each product. The various test series were kept in a thermostat-controlled stove for 24 hours at 20°C in darkness. Then the dead microorganisms were counted in a binocular microscope. Individuals that did not swim and lay on the bottom of the dishes and showed no movement were considered dead. The mortality percentage was calculated by microscope analysis of each dish, averaging the value of the 4 repetitions of each concentration. The data were subsequently process by Probits analysis to calculate, for each product, the 50% lethal concentration (LC50) and the 1% lethal concentration (LCI). The results of the acute toxicity tests are shown in Figures 1-3, wherein the mortality curves and the values of L and LC 50 are referred to 24 hours. In the three charts, the abscissae plot the concentration expressed as microg per ml "1 and the ordinates plot the mortality percentage. The charts show considerably toxicity of the three tested derivatives with respect to the microorganisms used in the tests. EXAMPLE 2 SETTLEMENT TEST 30-40 ciprys of Balanus amphitrite, obtained from nauplial cultures kept for 7-10 days in a thermostat-controlled chamber at 26° C were introduced in the dishes with the same method used in the nauplial toxicity test. The concentrations of the three above mentioned menadione derivatives prepared for this test were 0.01; 0.05; 0.1; 0.5; 1, 5, 10, 100 microg per ml "1 . The dishes were kept for 72 in a thermostat-controlled cabinet at 28°C with an L:D photoperiod of 12:12 at 1400 Lx. At the end of the 72 hours, the individuals settled were counted at the different concentrations with respect to the settlement noted in the control dishes. In this case also, four repetitions were carried out for each concentration. The settlement percentages were analyzed with the Probits method to obtain the values of EC 50 (concentration which inhibits settlement by 50%) and E (concentration which causes 1% inhibition). The results of the test are shown in Figures 4-6, which plot the settlement curves and the values of EC 50 . In particular, the abscissae plot the tested concentration of derivative, expressed as microg ml "1 , and the ordinates plot the settlement percentage of the microorganism. The three tested derivatives show values of EC50 lower than 1 microg ml "1 . The values plotted in the three charts indicate a high antifouling activity on the part of the tested components. The disclosures in Italian Patent Application No. MI99A002166 from which this application claims priority are incorporated herein by reference.

Claims: CLAIMS 1. Use of menadione and derivatives thereof as biocidal or antifouling agents with reduced ecotoxicity and polluting activity. 2. Use according to claim 1, wherein said derivatives are selected from the group consisting of menadione, menadione epoxide, menadione bonded with triazine, menadione bonded with piperazine and salts thereof. 3. Use according to claim 1 or 2, wherein said derivatives are selected from the group consisting of menadione triaminotriazine bisulfite(I), menadione(bis) piperazine bisulfite(II), menadione dimethylpyrimidinol bisulfite (MPB), menadione bisulfite nicotinamide salt or salt with nicotinic acid, menadione triaminotriazine, 2-methyl-2,3-epoxy-l,4-naphthalene- dione (III) and mixtures thereof. 4. Use according to any one of claims 1 to 3, wherein said menadione or derivatives thereof are added directly to the cooling water of an industrial plant or of an electric power station. 5. Use according to any one of claims 1 to 4, wherein said menadione or derivatives thereof are in association with a carrier suitable for direct application to items or structures in contact with water or ambient moisture. 6. Use according to claim 5, wherein said menadione or derivatives thereof have a concentration between 0.001 and 40% by weight. 7. Use according to any one of claims 1 to 3 as antifouling agents in antifouling paints. 8. Use according to any one of claims 1 to 3 in the prevention and slowing of molds formation. 9. Use according to any one of claims 1 to 3 in the paper industry. 10. Use according to any one of claims 1 to 3 in the tanning industry. 11. Use according to any one of claims 1 to 3 in the preventive treatment of fishing nets. 12. An antifouling paint comprising an antivegetative, biocidal effective amount of menadione derivative dispersed in a paint carrier. 13. The antifouling paint of claim 12, characterized in that said menadione derivative is selected from the group consisting of menadione, menadione epoxide, menadione bonded with triazine, menadione bonded with piperazine, and salts thereof.

Inventors: BONATI STEFANO, MONTELEONE FRANCESCO, BONATI, STEFANO, MONTELEONE, FRANCESCO
Applicants: BONATI STEFANO, MONTELEONE FRANCESCO, STOPPANI LUIGI SPA, BONATI, STEFANO, LUIGI STOPPANI S.P.A., MONTELEONE, FRANCESCO
Application year: 2000
Main classification: A01N35
IPC codes: A01N35, C09D5, D21H21