Antitumor effect of the natural compound 7α-acetoxy-6β-hydroxyroyleanone (Roy) in glioblastoma cell models

This study focuses on glioblastoma, a highly aggressive and deadly brain tumor characterized by a dismal 5-year survival rate of ~6% and the absence of effective treatments. This poor prognosis is largely due to tumor heterogeneity and the high rate of recurrence following conventional therapies. In this context, the researchers investigated the antitumoral potential of 7α-acetoxy-6β-hydroxyroyleanone (Roy), a natural compound isolated from the South African plant Plectranthus hadiensis Schweinf., to evaluate its ability to inhibit tumor growth. The study used tumor cells and advanced 3D tumor models, which more accurately mimic the tumor microenvironment. The results revealed that Roy significantly reduced tumor growth in 3D models and decreased the proliferative capacity of tumor cells, particularly in the presence of secretome derived from untreated tumor and immune cells. Additionally, Roy appears to interfere with key biological signaling pathways that tumors rely on for growth and survival.

A particularly noteworthy finding is the ability of Roy to cross the blood–brain barrier, a major obstacle in the treatment of brain diseases, as it prevents many therapeutic agents from reaching the brain. This ability substantially enhances the potential clinical relevance of this compound.

Overall, this study identifies Roy as a promising lead compound for the development of new therapeutic strategies against glioblastoma, a disease that currently has very limited treatment options and poor patient outcomes, offering a valuable direction for future research and drug development. It also underscores the importance of natural compounds as valuable sources for drug discovery and highlights the critical role of inflammation-related pathways in cancer progression.

Authors and Affiliations: 

Mariana Magalhães^1,2,3,4, Renato Spigarelli⁵, Eva María Domínguez-Martín^6,7, Lino Ferreira^2,4,8, Thomas Efferth⁹, Patrícia Rijo^7,10,11, Enzo Spisni⁵, Célia Cabral^3,4,12,13

¹PhD Programme in Experimental Biology and Biomedicine (PDBEB), Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal

²CNC-UC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal

³Coimbra Institute for Clinical and Biomedical Research (iCBR), Clinic Academic Center of Coimbra (CACC), Faculty of Medicine, University of Coimbra, Coimbra, Portugal

⁴CiBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal

⁵Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy

⁶Universidad de Alcala, Facultad de Farmacia, Departamento de Ciencias Biomédicas e Instituto de Investigación Química “Andrés M. del Río” (IQAR), Área de Farmacología, Grupos “Diseño, interacción y síntesis de compuestos biológicamente activos (DISCOBAC)” y “Bases moleculares de la resistencia en cáncer (CARE)”, Ctra. Madrid-Barcelona (Autovía A2), Alcalá de Henares, Madrid, Spain

⁷CBIOS Lusófona’s Research Center for Biosciences and HealthTechnologies, Campo Grand, Lisbon, Portugal

⁸Faculty of Medicine, University of Coimbra, Coimbra, Portugal

⁹Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Mainz, Germany

¹⁰Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal

¹¹Centro de Química Estrutural, Institute of Molecular Sciences, Universidade de Lisboa, Campo Grande, Coimbra, Portugal

¹²Faculty of Medicine, Instituto de Histologia e Embriologia, University of Coimbra, Rua Larga, Edifício da FMCU, Coimbra, Portugal

¹³Centre for Functional Ecology --Science for people and the planet (CFE), Department of Life Sciences, University of Coimbra, Coimbra, Portugal

Abstract:

Introduction: Glioblastoma (GB) is the most aggressive primary glioma, with a median survival of 15-18 months. Current treatments are often ineffective, largely due to tumor heterogeneity and recurrence. Advances in understanding GB’s molecular landscape and microenvironment have highlighted new therapeutic strategies to fight this life-threatening tumor. Given the pivotal role of natural compounds in drug discovery, those with anti-inflammatory and cytotoxic/cytostatic properties are emerging as promising candidates for GB therapy.

Methods: This study investigates the antitumor and immunomodulatory effects of 7α-acetoxy-6β-hydroxyroyleanone (Roy), a diterpene isolated by our team from Plectranthus hadiensis Schweinf., using both 2D and 3D GB cell models. U87 cells were used as a standard GB model and to generate monocellular and multicellular spheroids (U87, HMC3, and/or HBMEC cells). Both models were treated with 16 µM of Roy, a concentration previously shown to be tumor-specific.

Results: Roy significantly reduced spheroid size and metabolic activity over time, with the most pronounced effects observed in multicellular spheroids. This compound also inhibited cell proliferation by preventing colony formation and downregulating CDK4 and VEGFA mRNA levels. Roy’s bioactivity was enhanced in the presence of conditioned medium (secretome from GB and/or microglia cells), exerting a neuromodulatory effect by modulating IL6/JAK2/STAT3 mRNA expression and by suppressing the secretion of cytokines involved in the chronic inflammatory state within the GB microenvironment. Importantly, Roy was also able to cross the blood-brain barrier.

Conclusion: These findings, in line with our previous work, underscore the cytotoxic potential of this natural compound, suggesting Roy as a promising lead candidate for future GB treatment strategies.

Journal: Frontiers in Pharmacology

Link: https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2026.1728792/full