Chemoprevention of herb tea, Tabebuia avellanedae on in vitro and in vivo carcinogenesis system

As part of an ongoing project to investigate the anti-tumor and anti-tumor promoting properties of Tabebuia avellanedae, extract and its active compound, kind of Naphthoquinone (NQ801) was carried out. Tabebuiaavellanedae (TA), which is native in South America, is well known in traditional folk medicine used for the treatment of various disease. The inner bark of this plant produced in Brazil is distributed in Asia as a herb tea and healthy purpose. The application of a new screening procedure which utilizes the synergistic effects in enabled rapid and easy detection of naturally occurring substances (anti-tumor promoters, with inhibition of Epstein-Barr virus (EBV) activation, using Raji cells. These compounds were evaluated for their in vitro inhibitory effect on EBV-Early Antigen activation induced by TPA and exhibited potent inhibitory effects (70˜50% inhibition at 100µg concentration) on this assay. We have now extended these investigations to a tumorigenesis model in which we initiated the tumors with DMBA initiation and promoted with 1.7 nmol of TPA in two-stage mouse skin test. The control animals exhibited a 100% papilloma incidence at 20 weeks after promotion. However, treatment with the tested compounds (85 nmol) along with tumor promoter, reduced the percentage of tumor bearing mice by between 13.3–33.3at 20 weeks.These results provide a basis for further development of these botanical supplements for human cancer chemoprevention.