Senolytics

Senolytics are compounds that kill or remove cells that have already become senescent (zombie cells that stopped dividing but refuse to die, pumping out inflammatory signals), they're the cleanup side.

senescent cells accumulate with age and cause inflammation. the more senescent cells accumulate, the faster everything else degrades. By clearing these cells, senolytics aim to delay, prevent, or reverse age-related diseases, improve physical function, and extend a healthy lifespan.

sirtuins prevent cells from becoming senescent in the first place, senolytics remove the ones that already are.

senolytics are compounds that selectively kill senescent cells while leaving healthy cells untouched. they do this by temporarily disabling the survival pathways that senescent cells hijack to resist apoptosis — the programmed cell death that should have eliminated them. senolytics are drugs that selectively promote apoptosis of senescent cells by temporarily disabling the pro-survival pathways that enable senescent cells to resist the pro-apoptotic, pro-inflammatory factors that they themselves secrete.

data from early pilot human trials indicate that senolytics potently eliminate senescent cells, alleviate inflammation, and reduce frailty in humans. clinical trials for Alzheimer's disease, COVID-19, diabetes, eye disorders, lung fibrosis, osteoarthritis, osteoporosis, bone marrow transplantation, and childhood cancer survivors are currently underway.

senolytics reduce coronavirus-related mortality in old models. the mechanism: senescent cells are major amplifiers of the cytokine storm that makes COVID-19 fatal in older adults — clearing them before or during infection dramatically reduces the inflammatory response severity.

Key Senolytic Agents and Types:

Quercetin -
present in capers, onions, broccoli, apples, berries, and dozens of other common foods.
quercetin's senolytic activity operates through PI3K inhibition, the phosphoinositide 3-kinase pathway that senescent endothelial cells specifically upregulate as a survival mechanism. blocking PI3K in senescent cells triggers apoptosis.

quercetin also inhibits BCL-2 and BCL-xL at high concentrations (the anti-apoptotic proteins that prevent senescent cells from dying). the PI3K mechanism is endothelial cell-specific making quercetin particularly effective for vascular senescence (cardiovascular aging).

plain quercetin has poor oral bioavailability (absorbed at roughly 1–3% in standard supplement form). quercetin phytosome (quercetin complexed with phospholipids) dramatically improves absorption. the combination with dasatinib works partly because they complement each other's bioavailability profiles and target different senescent cell populations.

quercetin is simultaneously a SIRT1 activator (longevity), NF-κB inhibitor (anti-inflammatory), aldose reductase inhibitor (eye health), mast cell stabilizer (anti-allergenic), and antiviral across multiple virus types.

Dasatinib -
is a medicine that targets specific proteins in cancer cells and stops the cancer cells from growing.

when combined with Quercetins, has shown promising senolytic benefits, particularly in reducing senescent cell burden and improving age-related conditions. This combination, (known as D+Q), has been shown to alleviate symptoms of intervertebral disc degeneration, improve metabolic function, and potentially mitigate epigenetic aging.

D+Q decelerates epigenetic biological aging, slowing down the overall aging process.

D+Q treatment effectively eliminates senescent cells.

used to treat a certain type of chronic myeloid leukemia.

the intermittent dosing protocol: (3 days on, 4 weeks off) is specifically designed to minimize toxicity while maximizing senolytic benefit. side effects at standard CML doses (100-140mg daily) include fluid retention, pleural effusion, myelosuppression, and cardiac arrhythmia. the senolytic protocol uses much lower doses (50mg) on an intermittent basis.

D+Q dosing protocol from clinical trials: 500mg quercetin + 50mg dasatinib, 3 consecutive days per month, for 6 months. quercetin alone as a daily senomorphic (reduces SASP without killing cells) at 500-1000mg daily is a gentler ongoing protocol without requiring dasatinib.

Fisetin -
is a flavonoid compound found in various fruits and vegetables.
a pint of strawberries (approximately 450 grams) contains roughly 57 milligrams of fisetin, while a large apple might provide 8 milligrams.

recent research found fisetin to be one of the most effective senolytic compounds yet discovered among plant polyphenols. in mice, fisetin intake increased lifespan by nearly 10%, even when started late in life.

outperforms resveratrol and quercetin in extending lifespan and improving cardiac and cognitive health.

demonstrates superior brain penetration, achieving 65% clearance in hippocampal tissue compared to just 20% for D+Q.

selectively induces apoptosis in senescent but not proliferating human umbilical vein endothelial cells.

targets specific proteins expressed by senescent cells, such as SCAPs (Senescence-Associated Secretory Phenotype), leading to their removal.
can reduce senescence in various tissues, including muscle, brain, and adipose tissue.

fisetin crosses the blood-brain barrier and reduces cognitive decline in aging models, by lowering neuroinflammation, clearing senescent brain cells, boosting BDNF and glutathione, and protecting against amyloid-beta and tau pathology in Alzheimer's disease models.
improves bone health, and reduces age-related pathologies.

one challenge was that fisetin is rapidly metabolized in the digestive tract meaning very little is absorbed into the bloodstream. scientists developed a way to overcome this by combining it with natural compounds from fenugreek plant. this novel formulation increased bioavailability of fisetin by as much as 25 times.

the galactomannan (fenugreek fiber) complexation producing 25x bioavailability improvement is now commercially available. look for "Fisetin + Fenugreek galactomannans" formulations for maximum effect.

Dasatinib + Fisetin combination tested in rhesus monkeys showed significant reduction in p16+ and p21+ senescent cells in the epidermis at 7 weeks post-dosing with no negative outcomes — the most clinically advanced non-human primate senolytic data available.

Navitoclax -
synthetic BCL-2 family inhibitor, the most potent pharmaceutical senolytic identified.
developed as a cancer drug (targets BCL-2 and BCL-xL overexpression in cancer cells).

navitoclax works by targeting and inhibiting the Bcl-2 and Bcl-xL proteins, which are involved in preventing programmed cell death (apoptosis). By inhibiting the Bcl-2 and Bcl-xL proteins, navitoclax can induce apoptosis in senescent cells.

the only issue is the same BCL-xL inhibition that kills senescent cells also affects platelets.
thrombocytopenia (dangerous reduction in platelet count) is navitoclax's dose-limiting side effect at cancer doses.
current research focuses on selective BCL-xL inhibitors (A1331852 and A1155463) that retain senolytic potency with reduced platelet toxicity.

UBX0101 -

UBX0101 was an experimental senolytic drug designed to treat knee osteoarthritis (OA) by selectively eliminating senescent synovial fibroblasts.
It acted as a p53/MDM2 inhibitor, targeting and inducing apoptosis (programmed cell death) in senescent cells that contribute to joint degeneration.
Preclinical studies had shown it could reduce senescent cells and reduce cartilage damage. However, the human clinical trials did not confirm these results in treating pain and function in moderate-to-severe patients.