CONICET | Buscador de Institutos y Recursos Humanos

Many drugs used in oncology have been provided by nature. Contribution of plants to cancer treatment is evidenced by the success of drugs like vinblastine, topotecan, paclitaxel and oth-ers. Prosopis strombulifera (Ps) is a native plant from Mendoza popularly used as astringent, anti-inflammatory, odontalgic and anti-diarrheic agent. Our recent data show that Ps aqueous extract is cytotoxic against tumoral cell lines. The aim of the present study was to demonstrate the capability of aqueous extract to interfere with colorectal tumor progression in vivo and to identify its chemi-cal main components with cytotoxic activity. Tumor induction was performed in 3 groups (n=8) of BALB/c males, 6 weeks old, by 1,2-dimethylhydrazine (DMH, 21mg/kg/week, S.C., 22 weeks) administration. In vivo treatments were 5-fluorouracil (5FU, 30mg/kg /week, I.P) or Ps (150 mg/day in drinking water); both started 8 weeks after tumor induction; a third group did not receive any treatment. The phytochemical analysis was performed by specific reactions. Chemical constituents were fractioned by solid-liquid extraction and its cytotoxicity measured by MTT tetrazolium assay. Ps administration significantly increases animal survival from 24 weeks after tumor induction in non-treated group to 34.5 weeks (Mantel Cox, p=0.0188), while 5FU group survive 27 weeks. A qualitative phytochemical screening of the aqueous extract re-vealed a positive reaction for flavonoids, carbohydrates, sterols, terpenes and tannins; whereas, alkaloids, proteins and resins were are not detected. Between isolated fractions, only terpenes were able to induce cytotoxicity on HCT-116 human colorectal cells; while aqueous extract shows an IC50 of 502µg/ml, the isolated terpenes IC50 were 528µg/ml (5FU positive control was 8.86µg/ml). In conclusion, the present work makes Ps a promising natural product for cancer research and treatment, being terpenes the main candidates for further chemical-analytical studies.