In plain terms: Piperlongumine has not yet been tested in a human trial designed to measure the outcome relevant here. The available human research does not yet answer the question.
Piperlongumine
The evidence as the record states it
Not tested in humans. Preclinical senolytic activity, Wang et al. (Aging, 2016; PMID 27913811): piperlongumine preferentially killed senescent human WI-38 fibroblasts in culture by apoptosis, a process the authors report did not require reactive oxygen species; the abstract reports cell culture only. The authors filed a patent application on piperlongumine and its analogs as anti-aging agents, and two are a consultant to and a co-founder of a senolytic company. No human trial, dose, or safety data exist.
Why Grade D Route 1 and not Grade C
Grade D Route 1 applies when no qualifying human randomized trial has tested this compound or intervention against the relevant endpoint. Absence confirmed: piperlongumine AND randomized controlled trial[pt] AND humans[mesh] (PubMed, October 2026)
The first qualifying human RCT with a meaningful endpoint would move this to Grade C or higher, depending on what it shows.
What would move this grade
The first qualifying randomized controlled trial in humans, testing this intervention against a meaningful aging-relevant endpoint, would initiate grading. Depending on the result, it could land at any grade from A to D.