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|Molar mass||490.72 g/mol|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cycloastragenol is a molecule isolated from various species in the genus Astragalus that is purported to have telomerase activation activity. A single in vitro study on human CD4 and CD8 T cells led to claims that cycloastragenol may activate telomerase, leading to controversial claims for its role in reducing the effects of aging.
Cycloastragenol was studied by Geron Corporation and sold to T.A. Sciences in early 2013 who are developing it as a product named TA-65. Bill Andrews of Sierra Sciences has done testing on the anti-aging aspect of TA-65;[unreliable source?], as well as Maria Blasco in the journal Aging Cell, finding no increase in murine median or mean lifespan but some physiological anti-aging effects without augmenting cancer incidence. 
In late 2013, dietary supplement company RevGenetics released their conclusions on TA-65 that showed it is the single molecule cycloastragenol used in TA-65. More recently, on May 15, 2014 RevGenetics released a press release where they provide new information about a public UK government application where TA Sciences state (among other things) that the active ingredient in TA-65 is cycloastragenol.
Cycloastragenol intake improved health span but not lifespan in normal mice. Although the first TA Sciences study was done in 2005 for supplement based telomerase activators, in the 8 years since the first study, there has been no study done that shows a telomerase activator taken as a supplement has extended lifespan.
As part of a study sponsored by RevGenetics, the cycloastragenol-based product TA-65 was tested by UCLA scientist Rita B. Effros and RevGenetics scientist Hector F. Valenzuela. The small study (using T-cells taken from 6 participants) found that TA-65 activated telomerase in cultured cells in all samples, while another Astragalaus extract did not. The clinical significance of this work is uncertain.
Toxicity testing is limited and safety for the human consumer has not been adequately demonstrated. TA-65 was shown to improve biological markers associated with human health span through the lengthening of short telomeres and rescuing of old cells, although the significance of these findings in actual life expectancy is unknown. Publications in high-impact peer-reviewed journals are lacking however, and much of the online documentation supporting its use is sponsored by its manufacturers.
As disordered telomerase function is a feature of almost all cancers, there is an unknown, but theoretical risk of oncogene-mediated cancer promotion through the use of telomerase activators.
- Valenzuela, Hector F; Fuller, Thomas; Edwards, Jim; Finger, Danielle; Molgora, Brenda (April 2009). "Cycloastragenol extends T cell proliferation by increasing telomerase activity". J Immunol 182 (1_MeetingAbstracts): 90.30. Retrieved 19 July 2015.
- Dr. Bill Andrews anti-aging test of TA-65
- TA-65 Molecule is Cycloastragenol
- TA-65 is 98% Cycloastragenol
- TA-65 Study elongates short telomeres and increases health span of mice
- Valenzuela, Hector F; Effros, Rita B; Dimler, Taylor; Sweeney, Greg; Bateman, RileyH; Malgora, Brenda (14 January 2013). "Functional Assessment of Pharmacological Telomerase Activators in Human T Cells". Cells: 57–66. doi:10.3390/cells2010057.
- Harley, Calvin B; Liu, Weimin; Blasco, Maria; Vera, Elsa; Andrews, William H; Briggs, Laura A; Raffaele, Joseph M (1 February 2011). "A Natural Product Telomerase Activator As Part of a Health Maintenance Program". Rejuvenation Research 14 (1): 45–56. doi:10.1089/rej.2010.1085. PMC 3045570. PMID 20822369. Retrieved 19 April 2012.
- Shay, JW; Wright, WE (1 January 2001). "Telomeres and telomerase: implications for cancer and aging". Radiation Research 155 (1 pt 2): 188–193. doi:10.1667/0033-7587(2001)155[0188:tatifc]2.0.co;2. PMID 11121233.