Chemical and biological characterisation of Machaerium hirtum (Vell.) Stellfeld: absence of cytotoxicity and mutagenicity and possible chemopreventive potential

Machaerium hirtum (Vell.) Stellfeld (M.hirtum) is a plant known as 'jacarandá-bico-de-pato' whose bark is commonly used against diarrhea, cough and cancer. The aim of this study was to phytochemically characterise the hydroethanolic extract of this plant, investigate its antimutagenic activities using the Ames test and evaluate its effects on cell viability, genomic instability, gene expression and cell protection in human hepatocellular carcinoma cells (HepG2). Antimutagenic activity was assessed by simultaneous pre- and post-treatment with direct and indirect mutagens, such as 4-nitro-o-phenylenediamine (NPD), mitomycin C (MMC), benzo[a]pyrene (B[a]P) and aflatoxin B1 (AFB1), using the Ames test, cytokinesis blocking micronucleus and apoptosis assays. Only 3 of the 10 concentrations evaluated in the MTT assay were cytotoxic in HepG2 cells. Micronucleated or apoptotic cells were not observed with any of the tested concentrations, and there were no mutagenic effects in the bacterial system. However, the Nuclear Division Index and flow cytometry data showed a decrease in cell proliferation. The extract showed an inhibitory effect against direct (NPD) and indirect mutagens (B[a]P and AFB1). Furthermore, pre- and post-treated cells showed significant reduction in the number of apoptotic and micronucleated cells. This effect is not likely to be associated with the modulation of antioxidant genes, as shown by the RT-qPCR results. Six known flavonoids were identified in the hydroethanolic extract of Machaerium hirtum leaves, and their structures were elucidated by spectroscopic and spectrophotometric methods. The presence of the antioxidants apigenin and luteolin may explain these protective effects, because these components can inhibit the formation of reactive species and prevent apoptosis and DNA damage. In conclusion, the M.hirtum extract showed chemopreventive potential and was not hazardous at the tested concentrations in the experiments presented here. Moreover, this extract should be investigated further as a chemopreventive agent.

l-amino acid oxidase from Bothrops marajoensis causes nephrotoxicity in isolated perfused kidney and cytotoxicity in MDCK renal cells

Renal alterations caused by Bothrops venom and its compounds are studied to understand these effects and provide the best treatment. Previously, we studied the renal effect of the whole venom of Bothrops marajoensis and its phospholipase A2 (PLA2), but these effects could not to be attributed to PLA2. To continue the study, we report in this short communication the effects of l-amino acid oxidase from B. marajoensis venom (LAAOBm) on renal function parameter alterations observed in the same model of isolated perfused kidney, as well as the cytotoxic effect on renal cells. LAAOBm caused a decrease in PP, RVR, UF, GFR, %TNa(+) and %TCl(-), very similar to the effects of whole venom using the same model. We also demonstrated its cytotoxicity in MDCK cells with IC50 of 2.5 μg/mL and late apoptotic involvement demonstrated by flow cytometry assays. In conclusion, we suggested that LAAOBm is a nephrotoxic compound of B. marajoensis venom.