Constit. of Eugenia caryophyllata (clove) Biflorin is an o-naphthoquinone isolated from Capraria biflora L. (Scrophulariaceae, a perennial shrub widely distributed in several countries of tropical America). Biflorin has cytotoxic and antioxidant potential, strongly inhibiting the growth of five tested tumor cell lines, especially the skin, breast and colon cancer cells with IC50 of 0.40, 0.43 and 0.88 micro/ml for B16, MCF-7 and HCT-8, respectively, while the antioxidant activity was assayed against autoxidation of oleic acid in a water/alcohol system. (PMID: 16042338)