Riscos associados ao uso medicinal do extrato da casca de ipê-amarelo Handroanthus chrysotrichus e sua ação protetora em casos de envenenamentos pela serpente Philodryas patagoniensis: avaliação in silico, in vitro e in vivo

Abstract

Since ancient times, the use of medicinal plants has been among the popular practices to treat envenoming caused by various animals. Currently, in cases of snake envenoming, plant extracts are used as alternative therapy or as an adjunct to serum therapy. Treatment with antivenom is the procedure adopted in these cases, but it is limited both in its distribution and efficacy. In this context, different extracts of the Golden trumpet Handroanthus chrysotrichus are used in cases of ophidism. This is a tree belonging to the Bignoniaceae family and with wide distribution in Brazil. Thus, this study aimed: i) to investigate the phytochemical profile of the hydroethanolic extract of H. chrysotrichus bark and its pharmacological and toxicological potential in silico, in vitro, and in vivo; ii) to evaluate the therapeutic potential of the extract against the damage induced by the Philodryas patagoniensis snake venom in mice. For this, the hydroethanolic extract of the bark obtained by percolation was lyophilized and, at the time of the tests, it was solubilized in sterile saline solution (0.9%). The extract was tested in the model Artemia salina, indicating the presence of bioactive compounds through an LD50 of 276 μg. mL-1 (R² = 0.9912). Then, the extract was analyzed by colorimetric methods and GC-MS, which indicated high levels of polyphenols and the occurrence of α-curcumene, β-bisabolene, 4-(4- methylphenyl) pentanal, pentanoic acid and isoamyl acetate. Predictions of the in silico biological activities are in line with their traditional use and have a low probability of toxicity. The antioxidant properties (TAC, DPPH• and ABTS•+ scavenger, FRAP, Deoxyribose degradation test, and Fe++ chelation) of the extract, together with absence of in vitro cytotoxicity and genotoxicity, complement the in silico predictions. Data favorable to its use in traditional medicine (Article 1). However, acute exposure to the hydroethanolic extract in vivo caused oxidative damage in the brain, liver, and kidney tissues of mice from the concentration of 50 mg. kg-1 . In addition, there was a significant increase in creatinine of the group exposed to 100 mg. kg-1 and leukopenia (p<0.05) at all concentrations tested (10 – 100 mg. kg-1 ). Furthermore, sub-chronic exposure to the highest concentration of the extract (100 mg. kg-1 ) altered the behavior of the animals by decreasing the number of crossings in the open field test, and increasing the time spent on self-grooming. In this exposure, the brain and liver tissues of the mice also showed a significant increase in carbonylated proteins levels at all concentrations administered (Article 2). In order to evaluate the therapeutic potential of the extract in cases of envenoming, we proposed the use of P. patagoniensis venom as a toxic agent. This venom has a myotoxic, edematogenic, nociceptive, and hyperalgesic potential. Although it is a species whose accidents are neglected, its venom has activities similar to those of the genus Bothrops (Manuscript 1). Thus, behavioral tests of the animal group injected with the venom and treated with the extract, compared to the untreated group, showed a significant decrease in nociception and hyperalgesia. The protective effect of the extract is also verified in the measurements of edema and temperature induced by P. patagoniensis venom in the right hind paw of the mice over the days. Systemic damages, assessed by blood creatinine levels and oxidative damage in leukocytes and brain, liver, and kidney tissues, was minimized in the Golden trumpet treated group (Manuscript 2). In summary, the results presented here allow us to conclude that the hydroethanolic extract of H. chrysotrichus bark, used in traditional medicine to treat snake envenoming, has a protective action against the damage induced by P. patagoniensis venom. Mainly against the cardinal signs of inflammation and the systemic oxidative stress triggered by envenoming. Together, the data raise the possibility that the extract has adverse effects, which require precautions in its use. In this context, perspectives to future investigations on the use of this plant as a complementary therapy to traditional clinical treatment are open.