Antiparasitic Activity of Plumbago auriculata Extracts and Its Naphthoquinone Plumbagin against Trypanosoma cruzi

TLC and HPLC methods for the determination of plumbagin for the diagnosis of poisoning by Plumbago scandens L

Plumbago scandens L. (Plumbaginaceae) occurs in all regions of Brazil. It has been described as toxic to cattle and goats. Caustic lesions in the upper digestive tract characterize poisoning. P. scandens contains a naphthoquinone named plumbagin, which presents high cytotoxic activity. Plumbago auriculata Lam., a widely used ornamental plant, is considered potentially toxic, but there is limited data about its toxicity. This work aimed to validate analytical methodologies for determining the levels of plumbagin in samples of leaves, stems, and rumen content to be used as an auxiliary chemical marker in the laboratory diagnosis of intoxication. One methodology used thin layer chromatography (TLC), and another used high-performance liquid chromatography (HPLC). The presence of palisade grass (Urochloa brizantha (Hochst. ex A.Rich.) R.D.Webster), Guinea grass (Megathyrsus maximus (Jacq.) B.K.Simon & S.W.L.Jacobs), corn silage, and rumen content did not interfere with plumbagin in the two methodologies. The TLC methodology generates qualitative results but is simple to implement and has a low cost. The HPLC methodology showed a limit of detection (LOD) of 0.01 μg/mL and a limit of quantification (LOQ) of 0.05 μg/mL. Leaf and stem samples of P. scandens evaluated showed high levels of plumbagin (0.261 ± 0.087 % and 0.327 ± 0.055 %, respectively). In contrast, leaves of P. auriculata did not show detectable levels of the toxin, and some stem samples showed low levels (up to 0.000114 %). Thus, these methodologies can be used to confirm or rule out the consumption of P. scandens in rumen content from animals suspected of poisoning.

Synthesis and evaluation of photophysical, electrochemical, and ROS generation properties of new chalcogen-naphthoquinones-1,2,3-triazole hybrids

This study presents a comprehensive analysis encompassing the synthesis, structural elucidation, photophysical behavior, and electrochemical properties of a novel series of chalcogen-naphthoquinone-1,2,3-triazole hybrids. Employing a meticulously designed protocol, the synthesis of these hybrids, denoted as 11a-j, was achieved with remarkable efficiency (yielding up to 81%). This synthesis used a regioselective copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC). Furthermore, a detailed investigation into the photophysical characteristics, TDDFT calculations, electrochemical profiles, and photobiological attributes of compounds 11a-j was conducted. This exploration aimed to unravel insights into the excited state behaviors of these molecules, as well as their redox properties. Such insights are crucial for future applications of these derivatives in diverse biological assays.

Plumbagin: A Promising In Vivo Antiparasitic Candidate against Schistosoma mansoni and In Silico Pharmacokinetic Properties (ADMET)

Schistosomiasis, a potentially fatal chronic disease whose etiological agents are blood trematode worms of the genus Schistosoma spp., is one of the most prevalent and debilitating neglected diseases. The treatment of schistosomiasis depends exclusively on praziquantel (PZQ), a drug that has been used since the 1970s and that already has reports of reduced therapeutic efficacy, related with the development of Schistosoma-resistant or -tolerant strains. Therefore, the search for new therapeutic alternatives is an urgent need. Plumbagin (PLUM), a naphthoquinone isolated from the roots of plants of the genus Plumbago, has aroused interest in research due to its antiparasitic properties against protozoa and helminths. Here, we evaluated the in vivo schistosomicidal potential of PLUM against Schistosoma mansoni and the in silico pharmacokinetic parameters. ADMET parameters and oral bioavailability were evaluated using the PkCSM and SwissADME platforms, respectively. The study was carried out with five groups of infected mice and divided as follows: an untreated control group, a control group treated with PZQ, and three groups treated orally with 8, 16, or 32 mg/kg of PLUM. After treatment, the Kato-Katz technique was performed to evaluate a quantity of eggs in the feces (EPG). The animals were euthanized for worm recovery, intestine samples were collected to evaluate the oviposition pattern, the load of eggs was determined on the hepatic and intestinal tissues and for the histopathological and histomorphometric evaluation of tissue and hepatic granulomas. PLUM reduced EPG by 65.27, 70.52, and 82.49%, reduced the total worm load by 46.7, 55.25, and 72.4%, and the female worm load by 44.01, 52.76, and 71.16%, for doses of 8, 16, and 32 mg/kg, respectively. PLUM also significantly reduced the number of immature eggs and increased the number of dead eggs in the oogram. A reduction of 36.11, 46.46, and 64.14% in eggs in the hepatic tissue, and 57.22, 65.18, and 80.5% in the intestinal tissue were also observed at doses of 8, 16, and 32 mg/kg, respectively. At all doses, PLUM demonstrated an effect on the histopathological and histomorphometric parameters of the hepatic granuloma, with a reduction of 41.11, 48.47, and 70.55% in the numerical density of the granulomas and 49.56, 57.63, and 71.21% in the volume, respectively. PLUM presented itself as a promising in vivo antiparasitic candidate against S. mansoni, acting not only on parasitological parameters but also on hepatic granuloma. Furthermore, in silico, PLUM showed good predictive pharmacokinetic profiles by ADMET.