Abstract

The cactus pear (Opuntia spp.) is known to have bioactive compounds which work in the prevention of various diseases, especially cancer. The objectives of the study were to characterize the chemical profile and genetic diversity, through chromatic tests and ¹H NMR, using multivariate analysis, and assess the cytotoxic potential of cactus pear varieties of Opuntia and Nopalea genera grown in the semi-arid region of Brazil in dry and wet seasons. In the study of chemical prospecting and cytotoxic activity, crude ethanol extracts from cladodes of varieties (IPA-100003, IPA-100004, IPA-200021, IPA-200205, IPA-200008, IPA-200149 and IPA-200016) were used. The cytotoxic activity was evaluated by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl bromide tetrazolin] against HCT-116 (human colorectal), SF-295 (human glioblastoma) and OVCAR-8 (human ovarian cancer). The group of chemicals which stand out are the carbohydrates and glycosylated substances, lipids (fatty acids and steroids) and phenolic compounds (flavonoids), which vary both between the botanical varieties studied and among the collection periods. The analysis of the NMR spectra of ¹H cactus pear varieties by methods of multivariate analysis finds genetic diversity among the materials in the dry and rainy seasons. The ethanol extract (50 μg ml^-1) shows limited growth inhibitory effect on the cancer cell lines examined. It is concluded that the cytotoxic activity of cactus pear cladodes is attributed to phenolic compounds especially the flavonoids. It is recommended that population at risk utilize these materials as preventative natural dietary supplements against cancer.

Key words: Anticancer, cactus pear, flavonoids, food analysis, forage, phenolics, semiarid.