Brazilian Green Propolis: A Natural Weapon Against Cancer

Bees gather a resinous material named propolis from tree buds and other plant sources to safeguard and seal their hives. Known for its antimicrobial traits, propolis is used in traditional medicine to assist in healing wounds, bolstering the immune system, and treating a variety of illnesses.

Propolis has been used anciently in traditional medicine and has garnered interest from scientific communities in response to evidence showcasing its health benefits, such as antioxidant, anti-inflammatory, antimicrobial, antitumor, and immunomodulatory effects.

The composition of propolis varies depending on its source, geographical location, and the type of bee that produces it. Researchers connected with São Paulo State University (UNESP) in Brazil and the University of Southern Denmark (SDU) conducted an analysis of Brazilian green propolis, produced by the Africanized honeybee (Apis mellifera).

The primary component of this propolis is artepillin C (3,5-diprenyl-4-hydroxycinnamic acid), a phenolic compound primarily found in the resin of Baccharis dracunculifolia, a native Brazilian plant known locally as alecrim-do-campo. This plant is acknowledged for its antitumor properties.

Previous studies suggested that artepillin C can modify biological membranes, especially when the pH of the environment they are placed in is adjusted," explained Wallance Moreira Pazin, a faculty member of the Department of Physics and Meteorology at UNESP’s Bauru School of Sciences (FC).

The scientists decided to investigate how healthy and tumor cells responded on a biochemical level when exposed to artepillin C, focusing on fibroblasts - crucial cells in connective tissue healing and maintenance - and glioblastoma cells. Glioblastoma is the most frequently diagnosed primary brain cancer.

The pH of the culture medium was altered to determine whether a more acidic environment would have different effects with artepillin C. “This is pertinent because tumor tissue transforms glucose to lactic acid, making the extracellular microenvironment more acidic,” Pazin elaborated, first author of a research paper published in the Life journal.

The researchers then thoroughly studied the effects of propolis on cell membranes, employing an optical microscope to assess the membranes' integrity, fluidity, and structure. The study revealed that artepillin C interacted significantly with tumor cells, modifying their fluidity and potential for reorganization. It also initiated autophagy, a cleansing mechanism that involves the breakdown of old, abnormal, or malfunctioning cellular parts.

Supported by FAPESP through four projects, the study, Pazin said, enhances the understanding of how the substance works and offers ideas for future research that could lead to breakthrough cancer treatments.

"Nonetheless, although in vitro tests have shown high efficiency of this molecule's biological actions, oral or topical applications to patients would be limited by certain unique aspects, such as low absorption and bioavailability,” Pazin noted. “In this scenario, techniques to amplify its therapeutic action will be needed for advancements in using artepillin C against tumors. A good approach might be the use of nanocarriers for controlled release.”

Reference: “pH-Dependence Cytotoxicity Evaluation of Artepillin C against Tumor Cells” by Wallance M. Pazin, Renata R. Miranda, Karina A. Toledo, Frank Kjeldsen, Carlos J. L. Constantino, and Jonathan R. Brewer, published on 8 November 2023 in Life.