Larvicidal tablet based on Plectranthus barbatus leaves.

Description

/ 4 Larvicidal tablet based on Plectranthus barbatus leaves. Field of invention

[01] The present invention relates to a process for producing tablets containing Plectranthus barbatus leaf extract, an active ingredient of plant origin, with larvicidal action against Aedes aegypti. Fundamentals of the invention

[02] Dengue, chikungunya, yellow fever, zika, and mayaro are classified as arboviruses, where the main form of virus transmission is vector-borne, occurring through the bite of female mosquitoes, mainly A. aegypti, infected in the human-vector-human cycle. This group of diseases has become a growing global public health problem, mainly due to its potential for dispersal, its ability to adapt to new environments, the possibility of causing extensive epidemics, and the occurrence of a large number of severe cases, with neurological, articular, and hemorrhagic involvement (DONALISIO et al. Revista de Saúde Pública. 51:1-6. 2017). To reproduce, A. aegypti females employ oviposition strategies in different breeding sites, avoiding overcrowding and competition among larvae for space and food, which contributes to the success of their pantropical adaptation (TSUNODA et al. PLoS ONE. 9: e95606. 2014).

[03] Due to the vectorial nature of arboviruses transmitted by A. aegypti, the use of chemical insecticides to control vector populations is one of the most frequently used methods. Although they are efficient, the unplanned use of these compounds has led to undesirable effects that include high toxicity to non-target organisms and the selection of resistant insect populations, in addition to persistence in the environment, causing imbalance in the ecosystem (SANTOS et al. Revista Brasileira de Plantas Medicinais. 15(4): 757762. 2013).

[04] For this reason, the search for alternative methodologies, such as the use of plant extracts and other natural substances, is generally more Petition 870250053466, dated 06 / 25 / 2025, page 5 / 8 / 4 biodegradable and less toxic to non-target species, has grown widely. Plants possess defense mechanisms against insects that involve the synthesis, degradation, and transformation of chemical agents, which are divided into primary and secondary metabolites. Both have been investigated as possible control strategies, potentially acting as insecticidal toxins (SIMÕES et al. Pharmacognosy: From plant to medicine. 6: 1102. 2010). Considering the impacts caused by the use of synthetic products, natural compounds can be seen as promising alternatives.

[05] Plectranthus barbatus (Lamiaceae) is a species distributed throughout Africa, Asia, Australia, and South America. In Brazil, it is popularly known as falsoboldo, malva-santa, and boldo silvestre (LUKHOBA et al. Journal of ethnopharmacology. 103(1): 1-24. 2006). Several types of compounds have been isolated from different parts of the plant, including diterpenoids, essential oils, flavonoids, saponins, anthraquinones, and tannins. Secondary metabolites (α-pinene, eugenol, and β-caryophyllene) extracted from fresh leaves of P. barbatus were toxic to larvae of Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus (GOVINDARAJAN et al. Parasitology research. 115(2): 807-815. 2016). Extract of P. barbatus leaves in distilled water was toxic to fourth instar larvae of A. aegypti, however no insight into the mechanisms involved in this action was provided (MUSAU et al. International Journal of Mosquito Research. 3:12-17. 2016).

[06] In this sense, the present invention proposes the use of P. barbatus extract in tablet form as a larvicide for population control of A. aegypti, contributing to the reduction of the spread of arboviruses transmitted by it and the impacts caused by insecticides currently available on the market.

[07] The present invention is similar to that presented in patent BR 10 2020 012370 0 of June 18, 2020, differing in that it proposes a formulation based on an extract of complex composition containing secondary metabolites, mainly caffeic acid, a lectin (carbohydrate-binding protein) with affinity for ribose / galactose and a trypsin inhibitor. These components are involved in the different larvicidal mechanisms of action of Petition 870250053466, dated 06 / 25 / 2025, page 6 / 8 / 4 formulation, causing damage such as blocked development, altered permeability of the peritrophic matrix, inhibition of digestive enzymes, damage to the morphophysiology of the midgut of larvae, in addition to reducing the amount of carbohydrates in the cells of the intestinal epithelium, and causing microbiota imbalance and death. This complex composition and multiplicity of mechanisms of action is advantageous because it can delay or even prevent the emergence of resistant insect populations (MOSHI and MATOJU. Crop Protection. 92:16-28. 2017).

[08] The invention has an advantage over other insecticides, in addition to its natural origin, in its solid form which facilitates storage and application, requiring only the dissolution of the tablet in the desired location. Furthermore, each tablet contains a known dose of the active ingredient, making it easy to calculate the dose per volume of water to be treated, in addition to controlled release, increasing the stability of the active ingredients.

[09] The development of the formulation described in this report took into account the ease of obtaining the plant preparation, without the need for complex laboratory steps, and the high degree of polarity of the extract components, facilitating ambient dissolution with water. Furthermore, the choice of the tablet format was based on ease of application and storage, as well as economic viability. The formulation process aimed to convert powder (excipients) containing the active ingredient (plant extract) into an easy-to-apply product, ensuring the biological stability of the active ingredient in the tablet. Brief description of the drawings

[0010] Figure 1 shows an image of tablets containing Plectranthus barbatus leaf extract as the active ingredient. The image shows that the tablets are properly compacted and have an appearance and structure similar to other tablets on the market. Description of the invention

[0011] The present invention relates to a larvicidal formulation for Aedes aegypti with possible use in breeding sites containing stagnant water. A Petition 870250053466, dated 06 / 25 / 2025, p. 7 / 8 / 4 The formulation has as its active ingredient the extract of dried leaves of Plectranthus barbatus, popularly known as false-boldo.

[0012] The tablet was created from a mixture of the excipients microcrystalline cellulose, croscarmellose sodium, magnesium stearate and titanium dioxide in proportions (w / w) of 93.5%, 5%, 1% and 0.5% respectively, or in any concentrations, plus the active ingredient which we call P. barbatus leaf extract (42.57% in any concentration, w / w).

[0013] P. barbatus leaves were air-dried (28°C, 15 days). They were then ground in a blender (Philco, PH900), and the powder (10 g) was homogenized with 0.15 M NaCl (100 mL) in water for 16 ha at 28°C under magnetic stirring. The material was then filtered and centrifuged (3,000 g, 15 min) to obtain the extract.

[0014] All components of the formulation were in powder form and were mixed and subsequently pressed in a 12 mm diameter die, weighing 85.14 mg each. The tablets showed an average of 8 minutes for total disintegration when added to water. The tablets were tested for larvicidal action against A. aegypti of the Rockefeller strain, maintained in the laboratory. The tests were performed in triplicate and repeated five times. In both tests, the tablet was immersed in 20 mL of water, in which there were 20 larvae in each replicate. Two types of control were performed, one containing water and the other containing a placebo tablet (containing only the excipients, without the addition of the extract). Petition 870250053466, dated 06 / 25 / 2025, page 8 / 8

Claims

CLAIMS 1. “Larvicidal tablet based on Plectranthus barbatus leaf extract for Aedes aegypti characterized by containing the components Plectranthus barbatus saline extract (active ingredient) + microcrystalline cellulose, croscarmellose sodium, magnesium stearate and titanium dioxide (excipients).

2. “Larvicidal tablet based on Plectranthus barbatus leaf extract for Aedes aegypti”, according to claim 1, characterized by containing components in the following proportions: 42.57% Plectranthus barbatus leaf extract, 93.5% microcrystalline cellulose, 5% croscarmellose sodium, 1% magnesium stearate and 0.5% titanium dioxide.

3. “Larvicidal tablet based on Plectranthus barbatus leaf extract for Aedes aegypti”, according to claim 1, characterized by its use as a larval insecticide against Aedes aegypti.

4. “Larvicidal tablet based on Plectranthus barbatus leaf extract for Aedes aegypti”, according to claim 1, characterized by its use in the population control of Aedes aegypti by interrupting the biological cycle targeting the larval stage.

5. “Larvicidal tablet based on Plectranthus barbatus leaf extract for Aedes aegypti”, according to claim 1, characterized by being applied directly to breeding sites, added to sachets or by any other form of application. Petition 870240111479, dated 12 / 31 / 2024, pp. 24 / 26

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