Jarrow Formulas trans-Pterostilbene as pTeroPure is 99% pure pterostilbene. Pterostilbene is a naturally occurring, methylated form of resveratrol and has better uptake and metabolic stability in the body. Pterostilbene is a Calorie-restriction mimetic that activates the sirtuin pathway. Emerging science suggests that pterostilbene may exhibit special benefits in brain function and health.