Brazilian flora biodiversity has been widely investigated to identify effective and safe phytotherapeutic compounds. Among the investigated plant species, the Byrsonima genus exhibits promising biological activities. This study aimed at evaluating the cytotoxicity of B. correifolia, B. verbascifolia, B. fagifolia and B. intermedia extracts using different assays in two cell lines (primary gastric and HepG2 cells). The different extract concentrations effects on cell viability were assayed using the MTT, aquabluer, neutral red and LDH assays. Non-cytotoxic concentrations were selected to generate cell proliferation curves and to assess cell cycle kinetics by flow cytometry. Byrsonima extracts differentially affected cell viability depending on the metabolic cellular state and the biological parameter evaluated. B. fagifolia and B. intermedia extracts exhibited lower cytotoxic effects than B. correifolia and B. verbascifolia in all assays. The results obtained with LDH and flow cytometry assays were more reliable, suggesting that they can be useful in the screening for herbal medicine and to further characterize these extracts as phytotherapeutic compounds.

Our findings showed the following: (a) high concentrations of MB induced cytotoxicity and cell death by necrosis; (b) its antiproliferative effect was associated with G2/M arrest; and (c) its antioxidant activity could be responsible for the observed antimutagenic effects and for protective effects against gastrointestinal disorders previously described to MB. Although these effects are not specific to normal or tumor cells, they provide a panel of biological activities for further exploration.

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Chamomile is a medicinal plant, which presents several biological effects, especially the anti-inflammatory effect. One of the compounds related to this effect is apigenin, a flavonoid that is mostly found in its glycosylated form, apigenin-7-glucoside (APG), in natural sources. However, the affectivity and safety of this glycoside have not been well explored for topical application. In this context, the aim of this work was to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC-DAD) method to quantify APG in chamomile preparations. Additionally, the safety and the anti-inflammatory potential of this flavonoid were verified. The RP-HPLC-DAD method was developed and validated with linearity at 24.0–36.0 μg/mL range (r = 0.9994). Intra- and interday precision (RSD) were 0.27–2.66% and accuracy was 98.27–101.21%. The validated method was applied in the analysis of chamomile flower heads, glycolic extract, and Kamillen cream, supporting the method application in the quality control of chamomile preparations. Furthermore, the APG safety was assessed by MTT cytotoxicity assay and mutagenic protocols and the anti-inflammatory activity was confirmed by a diminished TNF-α production showed by mice macrophages treated with APG following LPS treatment.

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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.

Previous studies showed that lead (Pb) exposure may modulate gene expression by changes in the epigenetic status. However, little is known about the impact of Pb exposure and alterations on DNA methylation patterns in humans exposed to this metal. The aim of this study was to assess the consequences of exposure to Pb on DNA global methylation, in order to gain a better understanding of the interactions between Pb exposure and epigenetic effects. The study included 100 male workers employed in automotive battery factories from Paraná State, Brazil. Concentrations of Pb in blood (B-Pb) and plasma (P-Pb) were determined by ICP-MS, the percentage (%) of global DNA methylation was determined by quantification of 5-methylcytosine using indirect ELISA, and sociodemographic data collected by questionnaire by trained interviewers. The mean age was 37 ± 10 (18-67 years); 18% of participants were smokers, while 32% reported consumption of alcoholic beverages. The B-Pb and P-Pb levels were 20 ± 11 and 0.56 ± 0.64 µg/dl, respectively; % global DNA methylation was 2.8 ± 1.1% (ranging from 1.1 to 6.5%). B-Pb and P-Pb concentrations were significantly correlated. Furthermore, a marked association was noted between Pb biomarkers and DNA global methylation. Taken together, our data demonstrated that Pb exposure induced alterations on DNA global methylation in workers who were exposed to the metal and consequently may result in disturbances in the regulation of gene expression, leading to potentially several health adverse effect outcomes.

Dietary phenolic compounds such as caffeic and chlorogenic acid exert an antiproliferative effect and modulate the gene-specific DNA methylation status in human breast tumor cells, but it remains unclear whether they interfere with global DNA methylation in human leukemia cells. We examined whether caffeic and chlorogenic acid (1-250 mM) exert antitumor action in human promyelocytic leukemia cells (HL-60) and human acute T-cell leukemia cells (Jurkat). Caffeic and chlorogenic acid did not reduce cell viability in the two cell lines, as assessed using the neutral red uptake and MTT assays. These phenolic acids (1-100 mM) neither induced DNA damage (comet assay) nor increased the micronuclei frequency (micronucleus assay) in HL-60 and Jurkat cells, indicating that they were not genotoxic or mutagenic. Analysis of global DNA methylation levels using a 5-mC DNA ELISA kit revealed that chlorogenic acid at a non-cytotoxic concentration (100 mM) induced global DNA hypomethylation in Jurkat cells, but not in HL-60 cells, suggesting that it exerts a cell-specific effect. Caffeic acid did not change global DNA methylation. As other phenolic compounds, chlorogenic acid probably modulates DNA methylation by targeting DNA methyltransferases. The hypomethylating action of chlorogenic acid can be beneficial against hematological malignances whose pathogenic processes involve impairment of DNA methylation.