Potencial moluscicida de extratos e óleos essenciais de espécies vegetais para controle da transmissão da esquistossomose

Abstract

Schistosomiasis mansoni is a neglected disease with a high prevalence. Its causative agent is the trematode of the genus Shistosoma and its intermediate host is the snail of the genus Biomphalaria. Among the prophylactic measures is the use of molluscicides to combat the transmitting snail; the World Health Organization has recognized niclosamide as the standard drug, given its efficiency in controlling snails, but it has disadvantages, such as: high cost, increased resistance and high toxicity to aquatic organisms; thus making it necessary to research and develop new products, especially from plant species, given the complexity of their chemical composition and the possibility of diversifying their mechanisms of action. In this context, the aim of this study was to evaluate the potential of extracts from the leaves of Azadirachta indica A. Juss (neem) and the essential oils of Pterodon emarginatus Vogel (sucupira) and Psidium guineense Swartz (araçá) in controlling the transmission of schistosomiasis; as well as contributing to the validation of plant species in the fight against snails with a review study and extension actions on the subject. The methodology includes: a) a systematic review of studies evaluating molluscicidal activity with plant species collected in Brazil; b) investigation of molluscicidal activity in Biomphalaria glabrata (embryos, newly hatched and adults), characterization of the chemical composition and evaluation of toxicity (Artemia salina); c) preparation of a booklet for educational actions to control schistosomiasis. Chapter 1 presents the systematic review study, using the descriptors “molluscicidal activity” and “Biomphalaria”, covering the period from 2000 to 2024; with results indicating native species, of wide popular use and/or of great national occurrence. Chapter 2 evaluates the molluscicidal activity of Biomphalaria glabrata (embryos, newly hatched and adults), the chemical characterization of Azadirachta indica, Pterodon emarginatus and Psidium guineense, as well as the investigation of ecotoxicity parameters (Artemia salina); carried out with extracts of the dried and crushed leaves of Azadirachta indica, subjected to ultrasound maceration using 70% ethanol (hydromodule 1: 4); and with essential oils obtained from the leaves of Pterodon emarginatus and Psidium guineense by hydrodistillation in a Clevenger apparatus; with results indicating that all the plant species showed potential for use in the control of Biomphalaria, either as a molluscicide on adult snails, newly hatched snails and/or embryos, or by interfering with their feeding capacity; and although it was found to be toxic to Artemia salina, this result does not preclude its use as a molluscicide, considering that it can be used in artificial breeding sites; as well as its feasible use as nanoemulsions; Spathulenol, (-)-Caryophyllene oxide, Germacrene D, α-pinene, Copaene and/or Limonene are the majority compounds in Pterodon emarginatus and/or Psidium guineenses, which can be used as quality markers. Chapter 3 presents educational extension actions with the preparation of a booklet entitled “Schistosomiasis, water belly, snail disease and schistosomiasis. Do you know this parasitosis?”. Taken together, the study should stimulate the continuation of R&D into new bioproducts based on the association of the selected species, their isolated substances and nanoemulsion formulations; as well as encouraging new extension actions as an effective contribution to building a future with greater equity in health.