Ricardo San Martin, the Sutardja Center’s Alt: Meat Lab Director and Industry Fellow, is working on cultivating Quillaja saponaria — the Chilean soapbark tree — so it can be used in an upcoming COVID-19 vaccine candidate.
San Martin said he is studying saponins found in these trees, which are compounds that act as a natural foaming agent when put in water, for use in a COVID-19 vaccine. Recently, saponins received Food and Drug Administration approval to be used as adjuvants in vaccines, and they act as “an amplifier of whatever you inject,” San Martin said.
Adjuvants increase the impact of compounds in vaccines on the immune system, which means smaller amounts of a compound can still be effective, he added.
With his team in Chile, San Martin said he recently discovered that the leaves of some 2- to 3-year-old trees, which grow back, have high concentrations of the compounds needed for vaccines. Previously, research involved cutting down approximately 30-year-old trees for their bark.
“I am working as fast as I can to develop this new method from small trees because I would not be happy to be part of this development of industry if suddenly I wipe out all the trees from Chile,” San Martin said.
San Martin is working on ways to sustainably grow these Chilean soapbark trees. He hopes to plant plots of trees in both Chile and California, and he is currently studying the yields, the purity of the compounds and other information about these leaves.
Though he hopes for “good news” with upcoming vaccines, San Martin said many of the vaccines being developed do not use saponin adjuvants. Because of this, San Martin believes those vaccines will likely only work well in wealthy countries, as they have to be stored in ultra-low temperature freezers. Vaccines with saponin adjuvants can be distributed globally in refrigerators.
“For distribution to the rest of the world, it is a better approach and will be more affordable,” San Martin said.
Novavax, the vaccine development company utilizing this research, was awarded $1.6 billion from the government’s Operation Warp Speed in July to develop a COVID-19 vaccine.
Additionally, Novavax expects its “pivotal” clinical trial, which will include up to 30,000 participants, to begin in the United States and in Mexico by the end of November, according to Novavax press releases.
The UC Botanical Garden has five Chilean soapbark trees and supplied leaves and seeds for analysis and propagation for San Martin’s research, according to Holly Forbes, curator of the UC Botanical Garden.
Forbes said in an email that the samples were provided in a sustainable way, allowing the garden’s trees to continue to prosper and be available for additional research and teaching opportunities.
“Suddenly a tree that was just used for a foaming agent becomes a relevant actor in a vaccine,” San Martin said. “There is so much wealth in nature for us to learn.”