Bioavailability challenges associated with development of saponins as therapeutic and chemopreventive agents.

Saponins, a major class of natural phytochemicals, hold great promises for being developed into chemopreventive and chemotherapeutic drugs. However, one of the major factors limiting their pharmacological effects in vivo is poor bioavailability. This paper reviews the factors that determine the absorption and bioavailability of saponins including their physicochemical properties, and their absorption and disposition in the gastrointestinal tract. A critical review of the current research papers suggests that poor permeability and microflora hydrolysis of saponins are the primary factors that limit their bioavailabilities. Future investigations should be directed towards further optimization of the bioavailability of saponins to enhance their chemopreventive and chemotherapeutic effects in vivo.