RESUMO
Centella asiatica is a herbaceous plant of Asian traditional medicine. Besides wound healing, this plant is recommended for the treatment or care of various skin conditions such as dry skin, leprosy, varicose ulcers, eczema, and/or psoriasis. Triterpene saponins, known as centellosides, are the main metabolites associated with these beneficial effects. Considering the interest in these high value active compounds, there is a need to develop biosustainable and economically viable processes to produce them. Previous work using C. asiatica plant cell culture technology demonstrated the efficient conversion of amyrin derivatives into centellosides, opening a new way to access these biomolecules. The current study was aimed at increasing the production of centellosides in C. asiatica plant cell cultures. Herein, we report the application of a new elicitor, coronatine, combined with the addition of amyrin-enriched resins as potential sustainable precursors in the centelloside pathway, for a positive synergistic effect on centelloside production. Our results show that coronatine is a powerful elicitor for increasing centelloside production and that treatments with sustainable natural sources of amyrins enhance centelloside yields. This process can be scaled up to an orbitally shaken CellBag, thereby increasing the capacity of the system for producing biomass and centellosides.
RESUMO
The reactivity of 1,5-bis(trimethylsilyl)propargylic ethers 3 toward bases and electrophiles was investigated. Bispropargylic ethers 4, substituted allenyne ethers 6-8, and alpha-substituted bispropargylic ethers 9 were prepared in good yields, respectively, by protodesilylation, isomerization, or metalation/alkylation of bispropargylic protected alcohol 3. The ambident behavior of metalated synthon 3 was discussed and rationalized. Removal of the protecting groups of 9 easily afforded useful alpha-substituted bispropargylic alcohol.
