Title : Thapsia garganica L. in vitro plants as a new production platform of thapsigargins.
Abstract:
Thapsigargins are sesquiterpene lactones isolated from Thapsia garganica L., a Mediterranean plant. Thapsigargins are potent inhibitors of the sarco/endoplasmic reticulum Ca+2 -ATPase (SERCA) pump, increasing the cytoplasmic levels of free Ca+2 and inducing apoptosis. This mechanism was used to develop a Thapsigargin-based cancer drug, currently in Phase IIB clinical trials by Inspyr Therapeutics. Our current work is focused on the development of sustainable production platforms of this plant based on in vitro tissue culture. In vitro novel biomass from leaf explants, shoot regeneration and rooting was achieved. Thapsigargins production in shoot cultures growing in temporary immersion bioreactors (TIBs) have been enhanced using abiotic stress treatments. In vitro shoots are able to produce 0.34% and 2.1% dry weight of Thapsigargin and Nortrilobolide respectively, comparable with leaves and stems of wild T. garganica plants containing between 0.1 - 0.5% of Thapsigargin and below detectable levels of Nortrilobolide. In addition, in vitro shoots were used to study the regulatory role of the two only discovered genes, TgTPS2 and TgCYP76AE2, involved in the Thapsigargin biosynthesis trough Real Time-PCR.
