A towering tree planted along the roadsides of Cameroon and Uganda, valued mostly as an ornament and a source of shade, has emerged as an unlikely candidate in the fight against one of the world’s deadliest diseases. In a study published in Cancer Reports, researchers report that bark extracts of Erythrina excelsa Baker, a member of the legume family long used by traditional healers in south-western Cameroon to treat ovarian cysts, uterine fibroids and menopausal complaints, can kill breast cancer cells in the laboratory and sharply suppress tumor development in living animals. The findings add momentum to a growing global search for anti-cancer compounds rooted in ethnobotanical knowledge, particularly in regions where modern therapies remain costly, toxic and difficult to access.
The scientific motivation is stark. Breast cancer is the leading cause of cancer-related death in women worldwide, accounting for roughly 2.3 million new cases and nearly 685,000 deaths in 2020, about 30 percent of all cancers diagnosed in women. The burden falls especially hard in sub-Saharan Africa. In Cameroon alone, more than 4,000 new cases are recorded annually and over 2,000 women die of the disease. Standard treatments, including surgery, chemotherapy and hormone-blocking drugs such as tamoxifen, save lives but carry well-known liabilities: damage to healthy liver and kidney tissue, increased risk of secondary cancers, drug resistance, tumor recurrence and high costs. Against that backdrop, an estimated 80 percent of populations in Africa and Asia still rely on medicinal plants for primary health care, making rigorous scientific evaluation of those remedies a matter of both public health and drug discovery.
The research team, working with plant material harvested in Ngaoundere in Cameroon’s Adamawa region and authenticated at the National Herbarium of Cameroon, prepared two crude extracts from the tree’s stem bark: an aqueous extract made by soaking powdered bark in water for 24 hours, and a hydro-ethanolic extract using a 20 percent water, 80 percent ethanol mixture over 72 hours. Phytochemical profiling revealed a rich inventory of secondary metabolites in both preparations. Polyphenols dominated, at 348.78 milligrams of ascorbic acid equivalents per gram of dry weight in the aqueous extract and 434.22 in the ethanolic one, followed by flavonoids, tannins and flavonols. Consistent with this chemistry, both extracts showed potent free radical scavenging in the DPPH assay, with half-maximal inhibitory concentrations of roughly 19.7 and 17.2 micrograms per milliliter, and considerable ferric reducing power, confirming their capacity to neutralize the reactive oxygen species implicated in cancer initiation.
The in vitro results were striking. Tested against two human breast cancer cell lines, the estrogen-sensitive MCF-7 line and the aggressive triple-negative MDA-MB-231 line, both extracts inhibited growth in a dose-dependent manner within 24 hours. The ethanolic extract was the more potent, halting growth of MCF-7 cells at an IC50 of 41.63 micrograms per milliliter and MDA-MB-231 cells at 44.27, while the aqueous extract required 59.43 and 67.55 micrograms per milliliter respectively. Crucially, both extracts were far less toxic to non-cancerous human mammary epithelial cells, with IC50 values near 150 micrograms per milliliter, yielding a selectivity index above 2.5. That selectivity is the holy grail of cytotoxic drug development: a compound that kills cancer cells while sparing healthy ones.
Mechanistically, the extracts appear to work through two complementary routes. Flow cytometry showed that the aqueous extract pushed MCF-7 cells to accumulate in the DNA synthesis phase, raising the S-phase population from 15.75 percent in controls to 20.85 percent, while the ethanolic extract arrested cells at the G2/M checkpoint, increasing that population from 30.35 to 36.4 percent. Blocking the cell cycle at these points prevents mitotic entry and typically primes cells for apoptotic death. Fluorescence microscopy using acridine orange and propidium iodide co-staining confirmed that the aqueous extract triggered the morphological hallmarks of apoptosis, including membrane blebbing, chromatin condensation and the formation of apoptotic bodies, in both cancer cell lines. Apoptosis, or programmed cell death, is the preferred mechanism of cancer cell killing because, unlike necrosis, it minimizes inflammation and damage to surrounding tissue. Interestingly, neither extract significantly altered the cell cycle distribution of the triple-negative MDA-MB-231 cells, a reminder that the more aggressive molecular subtype may resist checkpoint regulation even as it succumbs to the extracts’ cytotoxic effects.
The decisive test came in living animals. The team induced mammary tumors in female Wistar rats using 7,12-dimethylbenz(a)anthracene, or DMBA, a polycyclic aromatic hydrocarbon carcinogen injected into the mammary region at 50 milligrams per kilogram of body weight. Every DMBA-exposed control rat developed tumors within the 140-day observation window, and two animals died. Rats treated daily by gavage with the aqueous bark extract at 75, 150 or 300 milligrams per kilogram fared dramatically better. Tumor incidence fell to 62.5 percent at the lowest dose and 25 percent at the middle dose, while tumor burden inhibition exceeded 85 percent at all doses, peaking at 99 percent at 150 milligrams per kilogram. Tamoxifen, the reference drug at 3.3 milligrams per kilogram, reduced tumor incidence to 37.5 percent and tumor burden by 44 percent. The extract also lowered tumor volume and slashed serum levels of CA15-3, a MUC-1-derived glycoprotein overexpressed in roughly 90 percent of breast cancers and widely used to monitor disease progression, to a degree comparable with tamoxifen.
Equally important was what the extract did to the biochemical environment that fuels tumor growth. DMBA exposure devastated the rats’ antioxidant defenses, elevating malondialdehyde, a marker of lipid peroxidation, while depleting glutathione and suppressing the activities of superoxide dismutase and catalase, the enzymes that detoxify superoxide anions and hydrogen peroxide. The bark extract reversed all of these changes, restoring redox homeostasis and protecting cell membranes from oxidative damage. It also tamed inflammation: DMBA raised serum levels of the pro-inflammatory cytokines TNF-alpha, IL-6, IFN-gamma and the angiogenic factor VEGF, all of which promote tumor progression and epithelial-to-mesenchymal transition through signaling pathways such as NF-kappaB and JNK. Treatment with the extract significantly reduced TNF-alpha, IL-6 and VEGF in a dose-dependent manner and boosted the anti-inflammatory cytokine IL-10 at the middle dose, suggesting it interferes with the inflammatory circuitry that enables tumors to grow, invade and recruit blood vessels.
Safety signals were reassuring across multiple fronts. Unlike tamoxifen, which caused progressive weight loss in treated rats consistent with its known anorectic effects, the extract produced no significant change in body weight over nearly five months of daily dosing. DMBA had elevated liver enzymes ALT and AST, alkaline phosphatase, bilirubin, urea and creatinine, hallmarks of hepatic and renal injury, and the extract normalized these markers in a dose-dependent fashion. Hematological analysis told a similar story: DMBA induced leukocytosis, anemia and elevated platelet counts, and the extract restored white blood cell, red blood cell, hematocrit and platelet values toward normal. Histology of the mammary glands showed that treated tumors lost their aggressive architecture, with only rare, loose tumor cell plaques persisting within necrotic areas at the highest dose. The authors note, however, that further work is needed to confirm activation of the intrinsic apoptotic pathway through caspase-9 and Bcl-2 family proteins, to characterize anti-estrogenic mechanisms directly, and to standardize the extract chromatographically with computational ADME modeling.
The study’s significance extends beyond a single plant. It demonstrates a rigorous pipeline, from traditional healer’s remedy to phytochemical characterization, selective cytotoxicity, mechanistic cell biology and long-term animal chemoprevention, that could be applied to the vast untested pharmacopoeia of African and Asian medicinal flora. If the polyphenol- and flavonoid-rich chemistry of Erythrina excelsa can be standardized, its active molecules isolated and its efficacy and safety confirmed in further preclinical and eventually clinical studies, a roadside tree of Cameroon may yet contribute a new, affordable and better-tolerated weapon against a disease that kills a woman somewhere in the world roughly every minute. For now, the message is one of validated promise: a remedy rooted in local knowledge has passed its first serious scientific examinations with remarkable results.
Subject of Research: Evaluation of the anti-breast cancer activity of Erythrina excelsa bark extracts in vitro and in vivo
Article Title: An In Vitro and In Vivo Assessment of the Anti‐Breast Cancer Activity of Erythrina excelsa Baker (Fabaceae) Bark Extracts
Article References: Walantini, J., Sipping, M. T. K., Ymele, M. N., Rebe, R. N., Yaya, J. A. G., Ndinteh, D. T., Njamen, D., & Zingue, S. (2026). An In Vitro and In Vivo Assessment of the Anti‐Breast Cancer Activity of Erythrina excelsa Baker (Fabaceae) Bark Extracts. Cancer Reports, 9(9), Article e70642. https://doi.org/10.1002/cnr2.70642
Image Credits: AI Generated
DOI: 10.1002/cnr2.70642
Keywords: breast cancer, Erythrina excelsa, chemoprevention, polyphenols, DMBA, apoptosis, antioxidants, tamoxifen, natural products, cell cycle arrest, CA15-3, ethnopharmacology
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Nathaniel Bowman. (September 12, 2026). African Tree Bark Extract Shows Striking Power Against Breast Cancer in Rats. Scienmag. https://scienmag.com/african-tree-bark-extract-shows-striking-power-against-breast-cancer-in-rats/
Nathaniel Bowman. “African Tree Bark Extract Shows Striking Power Against Breast Cancer in Rats.” Scienmag, 12 September 2026, https://scienmag.com/african-tree-bark-extract-shows-striking-power-against-breast-cancer-in-rats/. Accessed 12 September 2026.
Nathaniel Bowman. “African Tree Bark Extract Shows Striking Power Against Breast Cancer in Rats.” Scienmag. September 12, 2026. https://scienmag.com/african-tree-bark-extract-shows-striking-power-against-breast-cancer-in-rats/
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Tags: African tree bark extractantioxidantsapoptosisbreast cancerbreast cancer in sub-Saharan AfricaCA15-3cancer treatment accessibility in Africacell cycle arrestchemopreventionDMBAErythrina excelsaErythrina excelsa anticancer propertiesethnobotanical cancer researchethnopharmacologyherbal remedies for ovarian cysts and fibroidsinnovative cancer therapy from traditional knowledgenatural compounds for tumor suppressionnatural productsnatural solutions for chemotherapy side effectsphytochemicals in legume familyplant-based breast cancer treatmentplant-derived anti-cancer agentspolyphenolstamoxifentraditional medicine for cancer
