Anti-Skin Tumor Activity of Nutraceuticals from Strawberry, Coriander, Red Coral Lettuce and Chinese Chives

As part of the continuing validation of nutraceuticals with previously reported antioxidant activity in preventing chemically induced skin tumors, the anti-skin tumor activity of strawberry fruits and the leaves of coriander, red coral lettuce and Chinese chives were evaluated using the mouse skin tumor assay with dimethylbenz[a]anthracene (DMBA) as tumor initiator and croton oil as tumor promoter. Coriander effectively blocked the initiation of tumors but failed to suppress the tumor promotion stage. In contrast, strawberry was effective against the tumor promotion stage but was inactive against the tumor initiation step. Chinese chives effectively blocked both the tumor initiation and tumor promotion stages. Red coral lettuce was more effective when applied 1 h prior to croton oil while Chinese chives were more potent when applied immediately after croton oil. These nutraceuticals showed evidence of being chemopreventors and/or anti-tumor promoters. However, in all cases, the nutraceuticals did not stop the proliferation of skin tumors, once initiated and promoted, leading to skin tumor multiplicity.