Anti-HER2/neu activities of Brassica oleracea var. acephala L. (Collard greens) used by the Lumbee Tribe of North Carolina

Among the vegetable-containing plant families with proven anti-carcinogenic properties, the genus Brassica (cabbage family) has been determined to be effective at reducing the risk of cancer. Collard greens, a common food in Lumbee cuisine were collected in North Carolina and extracted with hot water or methanol of the dried plant materials. The MeOH extract was partitioned into four parts: hexane, ethyl acetate, n-butanol and water. The ethyl acetate partition reduced MCF-7 cell proliferation by 50% at 50 mg/ml. The extract and partitions were tested in a HER2/neu and EGF tyrosine kinase assays (96-well plates, high throughput). The methanol extract was active with an IC₅₀ of 10mg/ml, and the aqueous methanol (1:1) and ethyl acetate partitions of the methanol extract strongly inhibited the activity of protein tyrosine kinase HER2/neu, with an IC₅₀ of 5.5 mg/ml and 12.5 mg/ml, respectively. The extract also down-regulated the expression of the HER2/neu gene.