Breast cancer is the most common cancer worldwide. Santolina chamaecyparissus L. has successfully inhibited the MCF-7 cancer cell line. This study aims to evaluate the chemopreventive effects of S. chamaecyparissus aqueous extract (SCE) on female rats' physiological parameters with mammary cancer induced by N-methyl-N-nitrosourea (MNU).

The institutional ethics committee approved this study. Twenty-eight four-week-old female Wistar rats were divided into Control, MNU-induced (IND), SCE and SCE+IND. SCE was supplemented in drinking water (120µg/mL). At 50 days of age, MNU was intraperitoneally administered. Humane endpoints were evaluated weekly. After twenty-one weeks, animals were sacrificed by ketamine/xylazine overdose, and blood was collected. A complete blood count was performed using an automated haematology analyser. An autoanalyser was used to measure serum markers (albumin, cholesterol, glucose, and triglycerides). SCE’s chemical characterisation was performed by LC-MS, being found nineteen phenolic compounds, being the main molecules myricetin-O-glucuronide and 1,3-O-dicaffeoylquinic acid.

Regarding haemoglobin concentration, there was a difference (p=0.050) between SCE and Control (16.38±0.41g/dL and 15.18±0.29g/dL, respectively). Mean Platelet Volume differed between SCE+IND (8.29±0.15fL) and IND (9.03±0.26fL) (p=0.014). Platelet Distribution Width differed between 9.06±0.14fL (SCE+IND) and 10.58±0.42fL (IND) (p<0.001), but also between SCE (8.78±0.16fL) and SCE+IND versus control (9.86±0.17fL) (p=0.007 and p=0.034, respectively). SCE had no effect on the humane endpoints or serum markers.

Platelet size appears to be significantly affected by SCE. SCE supplementation had no effect on liver or kidney function or well-being in animals, implying it could be a viable treatment option for breast cancer. Histological analysis will help confirm SCE’s toxicological profile.