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Alzheimer's disease (AD) has been linked with oxidative stress, acetylcholine deficiency in the brain, and inflammatory processes. In the northeast region of Brazil, various plants are used to treat several diseases associated with these processes; then an antioxidant test was performed with those plants in a previous work and twelve species with higher antioxidant activity were selected for AChE inhibition evaluation. The phenolic compounds content was determined by Folin–Ciocalteu test and flavonoid content with AlCl3 reagent using UV-visible spectrophotometry. The antioxidant activity was assessed analyzing the inhibitory activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonate (ABTS) and by the β-carotene/linoleic acid system and acetylcholinesterase inhibition using qualitative and quantitative tests. The combination of better acetylcholinesterase inhibitory and antioxidant activities pointed out six species, in descending order, as the best potential sources of therapeutic agents against AD: Hancornia speciosa > Myracrodruon urundeuva > Copaifera langsdorffii > Stryphnodendron coriaceum > Psidium guajava > Mangifera indica. Besides, the phenolic compounds in the species probably contribute to these activities. However, further pharmacological studies to assess the specific applications of these plants against AD are required to confirm these results.

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This study aimed to evaluate the anthelmintic and ultrastructural effects of Calotropis procera latex on Haemonchus contortus. C. procera latex was twice centrifuged at 10,000×g and dialyzed to obtain a fraction rich in proteins, named LP (latex protein), and at 3,000 rpm to obtain a fraction rich in secondary metabolites, named LNP (latex non-protein). Specimens of H. contortus exposed to LNP, LP and PBS in the Adult Worm Motility Test (AWMT) were submitted to scanning (SEM) and transmission (TEM) electron microscopy to verify changes in their ultrastructure. Phytochemical tests in the LNP indicated the presence of phenols, steroids, alkaloids and cardenolides. High-Performance Liquid Chromatography (HPLC) characterized the presence of the compounds gallic acid and quercetin in the LNP. The protein content in the LP was 43.1 ± 1.1 mg/mL and 7.7 ± 0.3 mg/mL in LNP. In AWMT, LNP and LP inhibited the motility of 100% of the nematodes, with LNP being more effective than LP and ivermectin more effective than both (p <0.05). Cuticle changes were observed by SEM and TEM in nematodes treated with LP and LNP. Calotropis procera latex has anthelmintic effects against H. contortus, causing damage to its cuticle and other alterations in its ultrastructure.

Ouratea fieldingiana (Gardner) Engl is popularly used for wound healing. This study describes the main chemical compounds present in extracts of O. fieldingiana and evaluates their biological potential by investigating antifungal, antioxidant, and anticholinesterase activities. The action mechanism of main antifungal compound was investigated by molecular docking using the enzyme sterol 14-α demethylase, CYP51, required for ergosterol biosynthesis. The seeds and leaves were extracted with ethanol in a Soxhlet apparatus and by maceration, respectively. Both extracts were subjected to silica gel column chromatography for isolation of main constituents, followed by purification in sephadex. The structures of compounds were established by 1H and 13C-NMR spectroscopy and identified by comparison with literature data as amentoflavone and kaempferol 3-O-rutinoside, respectively. The antioxidant activities of the extracts were determined by the DPPH and ABTS free radical inhibition methods. In general, the extracts with the highest antioxidant activity corresponded to those with higher content of phenolic compounds and flavonoids. The ethanol extracts and two isolated compounds presented relevant antifungal activity against several Candida strains. The in silico findings revealed that the compound amentoflavone coupled with the CYP450 protein due to the low energy stabilization (-9.39 kcal/mol), indicating a possible mechanism of action by inhibition of the ergosterol biosynthesis of Candida fungi.

Insect resistance and environmental pollution are among the drawbacks of continuous use of synthetic insecticides against the vectors of dengue, Aedes aegypti and Aedes albopictus. The objective of this study was to analyze the composition of the essential oil of Lippia grata Schauer collected from plants, in three periods of the year, to compare the larvicidal activity and enzymatic inhibition of the dengue vectors. The oilsanalyzed by gas chromatography coupled to mass spectrometry (GC-MS), presented thymol and 1,8-cineole, as the main constituents, in all three periods. This composition was different from that found in previous studies of the species from different places, thus, suggesting a new chemotype of Lippia grata. Larvicidal tests were performed at concentrations of 100, 75, 50, 25, and 12.5 μg.mL−1 and the essential oil from the rainy season showed the best results, with LC50 of 22.79 μg.mL−1 and 35.36 μg.mL−1 against Ae. aegypti and Ae. albopictus, respectively; this result was better than other reports. In the rainy period, however, there was a greater variety of components, which led to a better larvicidal effect, possibly due to synergistic action with minor constituents. Total proteins, amylases, and acetylcholinesterase of both species were inhibited by the oils.