Arthur Barcelos Ribeiro

Breast cancer is the most common malignant neoplasm among women and exhibits high molecular heterogeneity, which directly influences therapeutic response and clinical outcomes. Despite advances in targeted therapies and immunotherapies, tumor recurrence, resistance to conventional treatments, and metastatic potential reinforce the need for more selective and effective pharmacological strategies. In this context, metal complexes, particularly ruthenium(II) derivatives, have attracted considerable attention due to their antitumor profile, greater selectivity, and lower systemic toxicity. Therefore, in the present study, the antineoplastic activity of the RuMTZ complex (2-mercaptothiazoline-di-1,2-bis(diphenylphosphine)ethane-ruthenium(II)) was evaluated in three breast cancer cell lines (MDA-MB-231, MDA-MB-468 and MCF7) and in one non-tumor breast cell line (MCF10A). RuMTZ exhibited greater cytotoxicity against human MDA-MB-468 cells, as demonstrated by cell viability (IC ₅₀ = 1.8 µM) and clonogenic (IC ₅₀ = 0.08 µM) assays, associated with higher selectivity indexes (3.89 and 3.75, respectively). Further studies demonstrated that RuMTZ inhibited cell migration by up to 62.76% and induced cell-cycle arrest in the G0/G1 phase, accompanied by a reduction in the G2/M population. Furthermore, the ruthenium complex induced apoptotic cell death, as observed by flow cytometry and increased levels of cleaved caspase-3 by Western blot. The genotoxic effect of RuMTZ was evidenced by the comet assay and increased γH2AX expression levels. Taken together, these findings demonstrate that RuMTZ exhibits promising antineoplastic activity against breast cancer cells, associated with cell-cycle arrest, induction of DNA damage, and apoptosis.

Ruthenium-based complexes have been explored as promising alternatives in antineoplastic therapy due to their enhanced selectivity for cancer cells. In this context, the present study evaluated the antitumor potential of the ruthenium complex [Ru(mtz)(dppe)2]PF6, named RuMTZ, in C57BL/6 mice bearing B16-melanoma, as well as its toxicity. In addition to tumor weight and mitotic frequency, cleaved caspase-3, γH2AX, and MAPK/ERK expression levels were analyzed by immunohistochemistry. The toxicity of the treatments was assessed through alterations in body and organ weight, biochemical parameters of liver and kidney function, and genotoxicity in bone marrow cells. RuMTZ led to a significant reduction in mitotic frequency and tumor weight, with a tumor growth inhibition rate equivalent to 94.9%. The antimelanoma activity of RuMTZ was accompanied by increased levels of cleaved caspase-3, γH2AX, and MAPK/ERK. These data indicate that RuMTZ induced DNA strand breaks, which may be, at least in part, related to the induction of caspase- and ERK1/2-mediated apoptosis. RuMTZ treatment, unlike cisplatin, showed no weight loss or impairment of liver and kidney functions. However, similar to other metallopharmaceuticals, it caused myelosuppression, evidenced by the absence of erythrocytes. These findings support the promising antitumor activity of RuMTZ, indicating its potential as a metallodrug.

Summary: IDH-wild-type glioblastoma (IDH-wildtype GB) is an aggressive and genetically heterogeneous tumor characterized by intrinsic resistance to radiotherapy and chemotherapy, while surgical resection remains inherently limited by its diffuse infiltrative growth, leading to poor clinical outcomes. Natural products such as solamargine (SM), a steroidal glycoalkaloid with cytotoxic and antitumor properties, have emerged as potential adjuvant strategies. Here, we investigated the effects of SM on proliferation, clonogenic survival, morphology and migration of IDH-wildtype GB cell lines (U-87MG, U-251MG and T98-G) and non-tumoral astrocytes under normoxic and hypoxic conditions, as well as its interaction with temozolomide (TMZ). Under normoxia, SM reduced cell viability in a dose- and time-dependent manner, with IC₅₀ values between 5.04 and 9.53 μM and showed enhanced cytotoxicity under hypoxia. TMZ alone displayed modest activity, and its combination with SM produced predominantly antagonistic effects. Clonogenic assays confirmed the antiproliferative potential of SM, with significant inhibition of colony formation at 2.5 μM. SM induced marked morphological alterations but did not significantly impair migration in wound-healing assays. In U-87MG cells, SM triggered G₂/M cell-cycle arrest, increased intracellular reactive oxygen species generation, and elevated γH2AX protein expression, indicating oxidative stress-associated DNA damage. However, cleaved caspase-3 and p53 were not detected, suggesting a predominantly non-apoptotic mode of cell death. Together, these findings support SM as a promising candidate for IDH-wildtype GB therapy and underscore the need for further studies to clarify its mechanisms of action and optimize its therapeutic use.

The present study investigated the cellular inhibitory effects of cis-trimethoxystilbene (cis-TMS) on the chemoresistant MDA-MB-231 breast cancer cell line and the role of p53 in mediating the cellular responses to this compound. Treatment with cis-TMS significantly inhibited the growth of MDA-MB-231 cells, reducing the cell viability by approximately 75% at 2.5 µM and increasing apoptosis rates to nearly 20%. Silencing p53 in MCF-10A and MCF-7 cell lines revealed that cis-TMS-induced apoptosis and cell cycle arrest were p53-dependent. The interaction studies suggest that cis-TMS does not alter the conformation of p53 at low concentrations but may influence its activity at higher doses. The results suggest that cis-TMS selectively targets cancer cells with functional p53, offering a potential targeted therapy approach. However, the reliance on p53 and the risk of genomic instability pose limitations, requiring further research to optimise the therapeutic strategies involving cis-TMS.

Mentha pulegium L., a medicinal plant, has been known for producing bioactive essential oils (EOs) that exhibit antibacterial, antifebrile and digestive properties. Thus, this study aimed at determining, for the first time, activities of essential oil from Mentha pulegium (EO-MP) against Xylella fastidiosa – which causes Citrus Variegated Chlorosis (CVC) – and Xanthomonas citri – which causes citrus canker. Antibacterial activities of EO-MP were evaluated and the minimum inhibitory concentration (MIC) values were determined by the broth microdilution method in 96-well microplates. Cytotoxic activity of EO-MP was evaluated at concentrations ranging from 31.25 to 1000 µg/mL in tumor and non-tumor human cell lines. EO-MP was active against X. fastidiosa (MIC = 20 µg/mL) and X. citri (MIC = 50 µg/mL). EO-MP showed no cytotoxic activity to human fibroblast cell line (GM07492A) with IC50 equivalent to 1024.87 µg/mL and was potentially toxic against cell lines HeLa, MCF-7, and U-251MG (with all IC50 = 100 µg/mL). GC-MS analyses revealed that pulegone (51.3%), 1,8-cineole (16.5%), menthone (11.2%), and menthol (10.0%) were its major constituents in EO-MP. In silico studies highlighted that 1,8-cineole was more active against X. fastidiosa and pulegone against X. citri. In sum, further in vivo investigations and the ones conducted in a greenhouse are needed.

Background/Objectives: Brazilian red propolis has attracted attention for its pharmacological properties. However, signs of toxicity were recently observed in long-term studies using the hydroalcoholic extract of red propolis (RPHE), likely due to polyprenylated benzophenones. This study aimed to develop a benzophenone-free red propolis extract (BFRP) and validate an HPLC-PDA method to quantify its main constituents: isoliquiritigenin, vestitol, neovestitol, medicarpine, and 7-O-methylvestitol. Methods: BFRP’s toxicity was assessed in zebrafish larvae through a vibrational startle response assay (VSRA) and morphological analysis. Genotoxicity was evaluated using the micronucleus test in rodents, and the extract’s effects on chemically induced preneoplastic lesions in rat colon were studied. An HPLC-PDA method was used to quantify BFRP’s main compounds. Results: BFRP primarily contained vestitol (128.24 ± 1.01 μg/mL) along with isoliquiritigenin, medicarpin, neovestitol, and 7-O-methylvestitol. Zebrafish larvae exposed to 40 µg/mL of BFRP exhibited toxicity, higher than the 10 µg/mL for RPHE, though no morphological differences were found. Fluorescent staining in the notochord, branchial arches, and mouth was observed in larvae treated with both BFRP and RPHE. No genotoxic or cytotoxic effects were observed up to 2000 mg/kg in rodents, with no impact on hepatotoxicity or nephrotoxicity markers. Chemoprevention studies showed a 41.6% reduction in preneoplastic lesions in rats treated with 6 mg/kg of BFRP. Conclusions: These findings indicate that BFRP is a safe, effective propolis-based extract with potential applications for human health, demonstrating reduced toxicity and chemopreventive properties.

Melanoma, an aggressive and potentially fatal skin cancer, is constrained by immunosuppression, resistance, and high toxicity in its treatment. Consequently, there is an urgent need for innovative antineoplastic agents. Therefore, this study investigated the antimelanoma potential of guttiferone E (GE). In an allogeneic murine B16 melanoma model, GE was administered subcutaneously and intraperitoneally. Antitumor evaluation included tumor volume/weight measurements and histopathological and immunohistochemical analysis. Furthermore, the toxicity of the treatments was evaluated through body/organ weights, biochemical parameters, and genotoxicity. Subcutaneous administration of 20 mg/kg of GE resulted in a significant reduction in both tumor volume and weight, effectively suppressing melanoma cell proliferation as evidenced by a decrease in mitotic figures. The tumor growth inhibition rate was equivalent to 54%. This treatment upregulated cleaved caspase-3, indicating apoptosis induction. On the other hand, intraperitoneal administration of GE showed no antimelanoma effect. Remarkably, GE treatments exhibited no toxicity, evidenced by non-significant differences in body weight gain, as well as organ weight, biochemical parameters of nephrotoxicity and hepatotoxicity, and genotoxic damage. This study revealed, for the first time, the efficacy of subcutaneous administration of GE in reducing melanoma, in the absence of toxicity. Furthermore, it was observed that the apoptotic signaling pathway is involved in the antimelanoma property of GE. These findings offer valuable insights for further exploring GE’s therapeutic applications in melanoma treatment. Graphical Abstract

Melanoma is the most aggressive and lethal type of skin cancer, characterized by therapeutic resistance. In this context, the present study aimed to investigate the cytotoxic potential of manool, a diterpene from Salvia officinalis L., in human (A375) and murine (B16F10) melanoma cell lines. The analysis of cytotoxicity using the XTT assay showed the lowest IC₅₀ after 48 h of treatment with the manool, being 17.6 and 18.2 µg/ml for A375 and B16F10, respectively. A selective antiproliferative effect of manool was observed on the A375 cells based on the colony formation assay, showing an IC₅₀ equivalent to 5.6 µg/ml. The manool treatments led to 43.5% inhibition of the A375 cell migration at a concentration of 5.0 µg/ml. However, it did not affect cell migration in the B16F10 cells. Cell cycle analysis revealed that the manool interfered in the cell cycle of the A375 cells, blocking the G2/M phase. No changes in the cell cycle were observed in the B16F10 cells. Interestingly, manool did not induce apoptosis in the A375 cells, but apoptosis was observed after treatment of the B16F10 cells. Additionally, manool showed an antimelanoma effect in a reconstructed human skin model. Furthermore, in silico studies, showed that manool is stabilized in the active sites of the tubulin dimer with comparable energy concerning taxol, indicating that both structures can inhibit the proliferation of cancer cells. Altogether, it is concluded that manool, through the modulation of the cell cycle, presents a selective antiproliferative activity and a potential antimelanoma effect.