Date Published: January 25, 2019
Publisher: Public Library of Science
Author(s): Dyego Gonçalves Lino Borges, Jessica Teles Echeverria, Tamires Lima de Oliveira, Rafael Pereira Heckler, Mariana Green de Freitas, Geraldo Alves Damasceno-Junior, Carlos Alexandre Carollo, Fernando de Almeida Borges, Paulo Lee Ho.
Plant extracts are a potential source of new compounds for nematode control and may be an excellent alternative for the control gastrointestinal nematodes that are resistant to conventional anthelmintics. However, research involving natural products is a complex process. The main challenge is the identification of bioactive compounds. Online analytical techniques with universal detectors, such as high-performance liquid chromatography-mass spectrometry (HPLC-MS), together with metabolomics could enable the fast, accurate evaluation of a massive amount of data, constituting a viable option for the identification of active compounds in plant extracts. This study focused on the evaluation of the ovicidal activity of ethanol extracts from 17 plants collected from the Pantanal wetland in the state of Mato Grosso do Sul, Brazil, against eggs of Haemonchus placei using the egg hatchability test. The ethanol extracts were obtained using accelerated solvent extraction. The data on ovicidal activity, mass spectrometry and metabolomics were evaluated using HPLC-DAD-MS, partial least squares regression analysis (PLS-DA) and a correlation map (univariate correlation analyses) to detect compounds that have a positive correlation with biological activity. Among the ten metabolites with the best correlation coefficients, six were phenylpropanoids, two were triterpene saponins, one was a brevipolide, and one was a flavonoid. Combinations of metabolites with high ovicidal action were also identified, such as phenylpropanoids combined with the triterpene saponins and the flavonoid, flavonoids combined with iridoid and phenylpropanoids, and saponins combined with phenylpropanoid. The positive correlation between classes of compounds in plants belonging to different genera and biological activity (as previously identified in the literature) reinforces the robustness of the statistical data and demonstrates the efficacy of this method for the selection of bioactive compounds without the need for isolation and reevaluation. The proposed method also enables the determination of synergism among the classes, which would be impracticable using traditional methods. The present investigation demonstrates that the metabolomic technique was efficient at detecting secondary metabolites with ovicidal activity against H. placei. Thus, the use of metabolomics can be a tool to accelerate and simplify bioprospecting research with plant extracts in veterinary parasitology.
Gastrointestinal nematodiasis (GIN) substantially affects cattle health, particularly in cases of co-infection by infectious and parasitic agents . Among parasitic species of veterinary concern, the hematophagous nematode Haemonchus placei is particularly pathogenic to cattle in tropical regions, causing hypoproteinemia, anemia, and anorexia in host animals , often with considerable economic losses.
The biological samples used in this study (plants and parasite) were registered with the SisGen plataform (code: A63DB37). All activities that were performed with animals respected the ethical principles adopted by the National Council for the Control of Animal Experimentation (NCCAE), and were approved by the Committee on Ethics in the Use of Animals / CEUA / UFMS with Protocol n°. 475/2012.
Despite the complex chemical profile of the species studied, it was possible to align the data with the aid of a pool of samples. The choice of univariate correlation methods is justified by the fact that we can directly list the main determinant compounds for biological activity and thus direct future research or studies aimed at the production of extracts enriched with these substances. A recent study has demonstrated the efficacy of this technique for the determination of active compounds from propolis extracts on biofilms of Staphylococcus aureus and Trichomonas vaginalis . In the present work, the positive correlation of the same classes of compounds in plants belonging to different genera and families reinforces the robustness of the statistical data and demonstrates the efficacy of the proposed tool for the selection of bioactive compounds without the need for the isolation and reevaluation. This method also enables determining synergism among classes of compounds, which would be impracticable using traditional methods.
The present investigation demonstrates that the metabolomic technique was efficient at detecting secondary metabolites with ovicidal activity against H. placei. Thus, the use of metabolomics can be a tool to accelerate and simplify bioprospecting research with plant extracts in veterinary parasitology. Moreover, it was demonstrated that phenylpropanoids were the compounds with a higher correlation to biological activity. Therefore, these metabolites are implicated in the ovicidal action against H. placei. Other classes, such as flavonoids and triterpene saponins, may act synergistically, increasing the activity of phenylpropanoids.