Preclinical validation study of the anticancer traditional use of uncaria tomentosa (Cat's claw)

Abstract

Uncaria tomentosa has been widely used in several countries as an anticancer remedy, but due to its pharmacological effects this plant has been extensively harvested and faces extinction.     Regardless of its traditional anti-tumoral use, root bark water extract was the lesser active extract. Hydroalcoholic preparation of the root bark showed LD₅₀ ranging from 150 to 500 μg/mL and leaf extracts (water and hydroalcoholic) showed LD₅₀ as low as 180.1μg/mL.  Selectivity index showed that except for astrocytoma and leukemia, all tumor cells were 2-8 times more sensitive to the extracts than to non tumor cells.  Oxindole pentacyclic alkaloids (mitraphylline, isomitraphylline, uncarine C and uncarine E) are present in the extracts and they probably play a role in the cytotoxic effect on tumor cell lines.  Our study suggets that Uncaria tomentosa roots could be replaced by the leaves in order to obtain good pharmacological results, protecting the plant from extinction.