Cancer is among the leading causes of mortality worldwide, and the treatment of breast and colorectal cancers presents significant challenges. Persistent inflammation and oxidative stress promote tumor growth, highlighting the importance of enhanced prevention and therapeutic strategies in veterinary medicine. Consequently, this research investigates the potential use of Rosmarinus officinalis L. extract (RE) as a biotherapeutic agent against chemically induced breast and colon cancers in rats. Carcinogens such as 1,2-dimethylhydrazine (DMH) and N-nitroso-N-methylurea (MNU) were administered to induce colon and breast tumors, respectively. Gas chromatography-mass spectrometry (GC/MS) was employed to identify active compounds within the crude aqueous ethanol extract, which demonstrated high antioxidant activity, achieving 92% DPPH scavenging. The extract also exhibited potent anticancer effects, reducing the viability of HT-29 (colon) and MCF-7 (breast) cancer cell lines by 82% and 88%, respectively. A total of 360 rats were divided into six groups: control (untreated, healthy rats), RE-only (rats receiving RE at 100 mg/kg for 12 weeks), breast cancer (BC) (induced with N-nitroso-N-methylurea [MNU], 50 mg/kg as a single dose), colon cancer (CC) (induced with 1,2-dimethylhydrazine [DMH], 20 mg/kg weekly for ten weeks), RE+BC (rats with MNU induction and RE treatment), and RE+CC (rats with DMH induction and RE treatment). Repeated in vivo experiments with DMH/MNU demonstrated that RE could mitigate precancerous phenotypes, including aberrant crypt foci (ACF) in colonic tissues and hyperplastic alveolar nodules in mammary glands. The therapy notably downregulated pro-apoptotic genes such as BCL2 and IL-1β, while upregulating Casp-3, and restored oxidative balance by normalizing levels of glucose, calcium, LDH, total antioxidant capacity (TAC), catalase (CAT), glutathione peroxidase (GPx), lipid peroxidation (LPO), and total phenolic content (TPC). Histopathological analysis revealed nearly normal tissue architecture, underscoring the protective role of RE against carcinogen-induced damage. These findings suggest that RE is a promising multi-targeted adjunct for the prevention and treatment of cancer, particularly through modulation of oxidative stress, inflammation, and precancerous lesions.

To Cite This Article: Alghamdi AM and Jalal AS, 2025. Rosmarinus officinalis L. extract with antioxidant and anticancer effects against 1,2-dimethylhydrazine and n-nitroso-n-methylurea-induced breast and colon carcinogenesis in experimental rat models. Pak Vet J. http://dx.doi.org/10.29261/pakvetj/2025.311