Senolytic Stack.

Quercetin interferes with several anti-apoptotic survival pathways that senescent cells depend on, including PI3K and BCL-2 family signalling. It is the component that appears in most published senolytic combinations, almost always alongside a second agent rather than alone. Nearly all of the supporting work is cell-based or in animals.

Fisetin differs from quercetin by a single hydroxyl and shows a similar profile against senescent cells in culture. Preclinical work has used intermittent high-dose schedules rather than daily low doses, which is a meaningful formulation difference. Human outcome data remains limited.

Resveratrol activates SIRT1-dependent deacetylation in cell systems, which touches the NF-kB signalling that drives the senescence-associated secretory phenotype. It behaves as a senostatic, damping the secretory output, rather than clearing cells. Oral bioavailability is low because of rapid glucuronidation.

Two methoxy groups in place of hydroxyls make pterostilbene more lipophilic and less rapidly conjugated than resveratrol. It engages the same stilbene-responsive signalling in cell models. Whether that pharmacokinetic difference translates into a different effect in people has not been settled.

Spermidine induces autophagy through inhibition of EP300-mediated acetylation, a route distinct from the apoptotic pathways that senolytic flavonols engage. Autophagic competence declines in senescent cells, so the two act at different points. Most of the supporting data is in cell and animal models.

Urolithin A is a gut microbial metabolite of ellagitannins that induces mitophagy, the selective clearance of damaged mitochondria. Mitochondrial dysfunction is one of the drivers of the senescent phenotype. Only some people carry the microbial capacity to make urolithin A from dietary precursors, which is why it is supplied directly.

NMN feeds the salvage pathway that maintains cellular NAD, the substrate consumed by sirtuins and by PARP enzymes during DNA damage response. Senescent cells consume NAD heavily. Raising NAD is a supply-side intervention and does not itself clear senescent cells.

Nicotinamide riboside is phosphorylated by NRK1 and NRK2 to NMN, then converted to NAD. It raises blood NAD metabolites in human trials, which is a marker and not an outcome. Combining it with senolytic agents pairs substrate supply with cell clearance.

NAD is the cofactor that sirtuins cleave to deacetylate their targets and that PARPs consume during DNA repair. Both activities rise with the DNA damage that accompanies senescence. Precursor forms rather than NAD itself are used orally because the intact dinucleotide is degraded in the gut.

Curcumin suppresses NF-kB activation in cell models, and NF-kB is the transcription factor that runs the senescence-associated secretory phenotype. That makes it senostatic in character, reducing signal output rather than removing cells. Absorption of unformulated curcumin is poor.

Luteolin engages several of the same kinase and BCL-2 family targets as the flavonols used in senolytic combinations. The evidence is largely cell-based and dose relationships in people are unclear. Read it as mechanistic overlap.

Apigenin inhibits CD38, the NADase whose activity rises with age and drains cellular NAD. Slowing consumption complements precursor supply from the other direction. This is enzyme-level and animal work rather than human outcome data.

EGCG affects several of the receptor tyrosine kinase pathways implicated in senescent-cell persistence in cell models. It also competes with other polyphenols for the same phase II conjugating enzymes. The pairing is common in formulation and thin in evidence.

Sulforaphane is among the strongest dietary inducers of Nrf2-driven phase II and antioxidant enzymes. Oxidative damage is one route into replicative senescence, so this arm acts upstream of the senolytic arm. Upstream and downstream are different jobs and neither substitutes for the other.

Piperine inhibits UDP-glucuronosyltransferase, the enzyme that clears quercetin, resveratrol and curcumin within hours of dosing. Raising exposure that way is the reason it appears in so many polyphenol blends. It raises exposure to everything conjugated by that route, which is a consideration rather than a free gain.

Phosphatidylcholine complexes raise the apparent solubility of quercetin, curcumin and related polyphenols, which are otherwise limited by dissolution rather than by permeability. Phytosome-style preparations are built on this. The gain is pharmacokinetic and does not change what the molecule does once inside a cell.

Coenzyme Q10 shuttles electrons between complexes I or II and complex III, and tissue levels decline with age. Where the stack's mitophagy arm removes damaged mitochondria, this arm supports the ones that remain. The rationale is mechanistic and not tested as a combination.