The liquid chromatography–mass spectrometry (LC-MS)-based metabolomics approach is a powerful technology for discovering novel biologically active molecules. In this study, we investigated the metabolic profiling of Orchidaceae species using LC-HRMS/MS data combined with chemometric methods and dereplication tools to discover antifungal compounds. We analyze twenty ethanolic plant extracts from Vanda and Cattleya (Orchidaceae) genera. Molecular networking and chemometric methods were used to discriminate ions that differentiate healthy and fungal-infected plant samples. Fifty-three metabolites were rapidly annotated through spectral library matching and in silico fragmentation tools. The metabolomic profiling showed a large production of polyphenols, including flavonoids, phenolic acids, chromones, stilbenoids, and tannins, which varied in relative abundance across species. Considering the presence and abundance of metabolites in both groups of samples, we can infer that these constituents are associated with biochemical responses to microbial attacks. In addition, we evaluated the metabolic dynamic through the synthesis of stilbenoids in fungal-infected plants. The tricin derivative flavonoid- and the loliolide terpenoidfound only in healthy plant samples, are promising antifungal metabolites. LC-HRMS/MS, combined with state-of-the-art tools, proved to be a rapid and reliable technique for fingerprinting medicinal plants and discovering new hits and leads.

Tetranychus urticae Koch is a polyphagous pest that is widely distributed throughout the world and causes considerable damage to crops in northeastern Brazil. The effects of the essential oil from Aristolochia trilobata L., selected constituents, and an artificial mixture (sulcatyl acetate, limonene, linalool, and p-cymene) on T. urticae in terms of fumigant action, residual contact, and fecundity were investigated under laboratory conditions. The results were compared with eugenol, Azamax^®, and Ortus^® as positive controls. Gas chromatography–mass spectrometry analysis of the oil revealed a predominance of monoterpenes, with sulcatyl acetate (24.57% ± 0.40%) as the major component, followed by linalool (10.80% ± 0.27%). Toxicity varied with the method employed. Through fumigation, the A. trilobata oil was about 2.18-fold more toxic than the artificial mixture, whereas no significant difference between the two products was found with regard to residual contact. Regarding the selected compounds, the mite was most susceptible to linalool and p-cymene by fumigation and residual contact, respectively. The plant-based (Azamax^®) and synthetic (Ortus^®) acaricidal agents were more toxic than the products tested. Moreover, low concentrations of the products investigated herein had no effect on mite survival, but a significant effect was found on the quantity of eggs laid by females. The A. trilobata oil and artificial mixture are promising natural acaricidal agents that have more than one mode of action (fumigation and residual contact) and exert an effect on fecundity. However, further studies are needed to evaluate the cost–benefit ratio for use on organic crops and protected environments in northeastern Brazil.