Phytoecdysteroid accumulation in plants and bioactivities in animal models

Phytoecdysteroids are plant-produced polyhydroxylated steroidal compounds that have valued bioactivities including plant defense against herbivorous insects, and growth and performance-enhancing properties in mammals. In this program of research, phytoecdysteroid accumulation was investigated in Ajuga turkestanica (Regel) Briq., a medicinal herb indigenous to Central Asia, and in spinach (Spinacia oleracea L.), a valuable crop produced worldwide, and purported bioactivities were examined in in vitro and in vivo mouse models. Results showed that A. turkestanica hairy root cultures were a sustainable alternative source of valued phytochemicals compared to wild-harvesting (Chapter 2). Extracts from both wild-harvested A. turkestanica shoots and hairy root cultures enhanced protein synthesis in murine cell cultures. In spinach, significant variations in phytoecdysteroid accumulation in seeds and shoots was demonstrated, which may help further investigations of plant defense properties and biosynthetic regulation (Chapter 3). A review of strategies to investigate anabolic effects of phytoecdysteroids lead to the evaluation of a continuous infusion of 20-hydroxyecdysone, the predominant phytoecdysteroid, on body tissue composition and skeletal muscle gene expression (Chapters 4 and 5) in mice. The mass of the triceps brachii muscles was significantly increased, however, no differences between treatment groups were observed in the other parameters measured. Ingenuity Pathways Analysis identified genes with the most evidence for differential expression from microarray gene expression data, which included genes involved in cellular growth and proliferation and cell-to-cell signaling and interaction. These results provide leads and resources for future research on phytoecdysteroids, which have demonstrated potential in improving agriculture and human health