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The chemical composition of the essential oils of Mentha arvensis and Mentha piperita and their antimicrobial activity against twelve Aeromonas spp. isolates from tambaquis (Colossoma macropomum), an important native farmed fish species in Brazil, were evaluated. The oils were characterized using gas chromatography and mass spectrometry (GC/MS) and their antimicrobial activity was evaluated through the microdilution method. The essential oils of these Mentha species mainly comprised oxygenated monoterpenes (97.1% for M. arvensis and 86.2% for M. piperita) and menthol was the major compound of these oils (86.1% for M. arvensis and 33.8% for M. piperita). It was confirmed that these oils had antimicrobial activity against 12 isolates of Aeromonas spp., with minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) ranging from 1,250 to 16,666.7 μg mL−1. Better antimicrobial activity was achieved by the M. arvensis essential oil. [ABSTRACT FROM AUTHOR]

Lippia origanoides Kunth (LO, Verbenaceae), commonly known in Brazil as salva-de-marajó, is an aromatic plant native to the Americas. Quilombola women from Oriximiná (Pará State, Brazil) use decoctions and decoction vapors of LO aerial parts orally or in sitz baths to alleviate symptoms of dysmenorrhea. This study aimed to evaluate LO decoctions and essential oils through a chemo-qualitative approach. Aerial parts of LO were collected from two individuals, and other two commercial samples were acquired from a public market. Aqueous extract of each sample was obtained by decoction and spray drying. The spray-dried decoctions were chemically characterized using UPLC-APCI(-)-IT-MS 2 and cluster heatmap analysis to discern compositional patterns. Essential oils were obtained through hydrodistillation and analyzed using GC-MS and GC-FID. In total, 12 compounds were tentatively identified from LO decoctions. Their product ion spectra were characteristic of flavonoid aglycones (5) and glycosides (4), and phenylpropanoids, including two stilbene glycosides and one hydroxycinnamic acid glycoside. Variations were noted in the chemical fingerprints of the decoctions, but the flavonoid glycosides orientin, isoorientin, and vitexin emerged as potential markers for the species. The essential oils of the samples contained high amounts of oxygenated monoterpenoids, with a predominance of the p-menthanes carvacrol (up to 61.9 %) and/or thymol (up to 17.0 %), and p-cymene (up to 24.9 %). This study was the first to explore the chemical composition of decoctions derived from LO, highlighting the species as an untapped source of phenolic glycosides, an aspect that has received limited discussion thus far., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Herbal extracts have been investigated as an alternative for parasite control, aiming to slow the development of resistance and to obtain low-cost biodegradable parasiticides. The goal of this study was to evaluate the efficacy, in vitro, of 11 essential oils from Brazil on reproductive efficiency and lethality of the cattle tick Rhipicephalus (Boophilus) microplus. The effects of oils extracted from Curcuma longa, Zingiber officinale, Lippia alba, Lippia gracilis, Lippia origanoides, Lippia sidoides, Mentha arvensis, Mentha piperita, Croton cajucara (white and red), and Croton sacaquinha on ticks were investigated by the Immersion Test with Engorged Females (ITEF) and the modified Larval Packet Test (LPT). Distilled water and 2% Tween 80 were used as control treatments. Chemical analysis of the oils was done with gas chromatography coupled with mass spectrometry. Analysis of the in vitro tests using Probit (SAS program) allowed the calculation of lethal concentrations (LCs). Lower reproductive efficiency indexes and higher efficacy percentages in the ITEF were obtained with the oils extracted from C. longa (24 and 71%, respectively) and M. arvensis oils (27 and 73%, respectively). Lower LC50 was reached with C. longa (10.24 mg/mL), L. alba (10.78 mg/mL), M. arvensis (22.31 mg/mL), L. sidoides (27.67 mg/mL), and C. sacaquinha (29.88 mg/mL) oils. In the LPT, species from Zingiberaceae and Verbenaceae families caused 100% lethality at 25 mg/mL, except for L. sidoides. The most effective oils were from C. longa, L. gracilis, L. origanoides, L. alba, and Z. officinale. The LC50 and LC90 were, respectively: 0.54 and 1.80 mg/mL, 3.21 and 7.03 mg/mL, 3.10 and 8.44 mg/mL, 5.85 and 11.14 mg/mL, and 7.75 and 13.62 mg/mL. The efficacy was directly related to the major components in each essential oil, and the oils derived from Croton genus presented the worst performance, suggesting the absence of synergistic effect among its compounds. Since C. longa, containing 62% turmerone, was the one most efficient against ticks, this compound may be potentially used for tick control, but further research is needed, especially to assess toxicity of these compounds to the host. These new studies, together with the results presented here, may provide a strong rationale for designing pre-clinical and clinical studies with these agents., (Copyright © 2016 Elsevier GmbH. All rights reserved.)