Efeitos do extrato bruto de Sida rhombifolia L. sobre marcadores de toxicidade em diferentes modelos experimentais

Abstract

The use of medicinal plants is on the rise for different reasons, from a search for health as a whole, disease prevention and maintenance of well-being, vitality and quality of life. Sida rhombifolia (Malvaceae), a plant known by the name of guanxuma, is popularly used for the treatment of different pathological conditions. However, there is a lack of studies that identify its bioactive molecules and validate their potential pharmacological properties. Therefore, the aim of study was to produce and determine the phytochemical constitution of the crude extract of aerial parts of S. rhombifolia (EBSR), to evaluate its safety in models of cytotoxicity, acute toxicity and repeated doses - 28 days, antibacterial and antitumor activities. EBSR was obtained through 70% hydroalcoholic maceration and its composition was determined by phytochemical analysis and high performance liquid chromatography coupled to mass spectrometry and diode detector (HPLC-DAD-MS). In vitro toxicity investigation was performed on human peripheral blood mononuclear cells (PBMCs). Studies of antitumor activity were performed using cell viability tests. The in vivo acute and repeated dose toxicity assessment was performed in Wistar rats and developed according to the Organization's Protocols for Economic Cooperation and Development (OECD), with doses of 2000 mg/kg for acute toxicity assessment and 150, 300 and 600 mg/kg for repeated dose toxicity. The EBSR analysis showed the presence of caffeic acid, coumarin and rutin in its composition. PBMCs exposed to EBSR remained viable at concentrations of 75 and 125 µg/mL. Regarding antitumor activity, EBSR presented an ability to reduce by 50% (IC50) of 478.63, 587.48, and 637.07 µg/mL on cervical (Hela), breast (MCF-7), melanoma (A375) cancer cells, respectively, and had an action in the significant decrease of cell viability in EBSR concentrations from the dose of 75 µg/mL. EBSR did not cause mortality or behavioral changes in both experimental models of in vivo toxicity assessment. In the repeated dose experiments, both hematological and biochemical markers were within the reference values for the species. In both cases, the vast majority of toxicity markers remained unchanged, which demonstrates the maintenance of homeostasis in the animals and exemption from toxicity caused by the administration of EBSR. Therefore, EBSR proved to be safe for in vivo administration at the doses analyzed.