Selegiline

Limits on what this shows

• Key negative/null findings: No source located in this review contradicts the mitochondrial-protective direction. Wahdan SA, Tadros MG, Khalifa AE (Naunyn Schmiedebergs Arch Pharmacol, 2017, PMID 28643087), which reported antioxidant/antiapoptotic protection by selegiline against 3-NP neurotoxicity, was located during this review and is explicitly excluded from the evidence base because it was formally retracted in 2023; it is not cited in support of this entry and is listed under Sources only for transparency.
• At-risk subgroups: Not established; findings are from toxin-, chemotherapy-agent-, or ischemia-challenged neuronal models, not baseline healthy-tissue measurements, and do not translate directly to a patient population or subgroup.

Regulatory status

Not addressed in the FDA/DailyMed labeling for either formulation; mitochondrial pharmacology is not part of the approved labeling basis for selegiline.

Population evidence

Entirely preclinical, cell-culture and animal models, drug-specific (deprenyl/selegiline named directly, not a class member): Szilagyi G, Simon L, Wappler E, Magyar K, Nagy Z. J Neurol Sci. 2009 (PMID 19332347), deprenyl-N-oxide metabolite preserved mitochondrial function in PC12 cells and gerbil transient brain ischemia, "augmented Bcl-2 protein expression" cited as the responsible factor. Paterson IA, Zhang D, Warrington RC, Boulton AA. J Neurochem. 1998 (PMID 9453545), R-deprenyl "prevented the ara C-induced loss of mitochondrial function" in cerebellar granule neurons. Simon L, Szilagyi G, Bori Z, Orbay P, Nagy Z. Eur J Pharmacol. 2001 (PMID 11711036), D-deprenyl "maintain[ed] the mitochondrial membrane potential by influencing intracellular anti-apoptotic oncoproteins, such as Bcl-2" in experimental brain ischaemia. Tatton WG, Chalmers-Redman RM. Neurology. 1996 (PMID 8959986) and Tatton WG, Wadia JS, Ju WY, Chalmers-Redman RM, Tatton NA. J Neural Transm Suppl. 1996 (PMID 8988461), both reporting deprenyl-related compounds "reduce neuronal apoptosis...through mechanism(s) that does not require MAO-B inhibition." Ebadi M, Sharma S, Shavali S, El Refaey H. J Neurosci Res. 2002 (PMID 11813232), reviewing that selegiline "blocks apoptosis-related fall in the mitochondrial membrane potential." None of this evidence is a human clinical trial; no study in this review directly measured mitochondrial membrane potential or Bcl-2 expression in selegiline-treated patient tissue.

Mechanism

Named. The propargylamine structure shared by selegiline and related compounds is reported to act through gene-transcription-dependent upregulation of anti-apoptotic Bcl-2/Bcl-xL and preservation of mitochondrial transmembrane potential, a pathway the Tatton group explicitly reports as separate from MAO-B inhibition itself.

Counter-evidence held on record

All located evidence runs protective; no source shows selegiline causing mitochondrial harm. The evidence base is entirely preclinical (cell culture and animal), and no human trial in this review directly confirms the mechanism in patients. This is a protective, reverse-direction finding, not a depletion risk, and must never be recast as one. It must never be read as implying mitochondrial-support supplementation (CoQ10, L-carnitine, alpha-lipoic acid, or similar) is indicated, needed, or that selegiline itself causes mitochondrial harm; the located evidence shows the opposite, and even that is preclinical only. No supplementation is implied or recommended by this entry.

Limits on what this shows

• Key negative/null findings: None located contradicting the protective direction for the confirmed in vitro finding. The inaccessibility of the Kushleika human study specifically prevents confirmation either way for the human-cohort portion of this entry, and that gap is disclosed rather than assumed favorable.
• At-risk subgroups: Not established.

Regulatory status

Not addressed in the FDA/DailyMed labeling for either formulation.

Population evidence

In vitro, drug-specific: Khaldy H, Escames G, Leon J, Vives F, Luna JD, Acuna-Castroviejo D. J Pineal Res. 2000 (PMID 10981823), "Comparative effects of melatonin, L-deprenyl, Trolox and ascorbate in the suppression of hydroxyl radical formation during dopamine autoxidation in vitro," directly testing selegiline (L-deprenyl) itself alongside established antioxidants. Animal, drug-specific by title: Takahata K, Shimazu S, Katsuki H, Yoneda F, Akaike A. J Neural Transm (Vienna). 2006 (PMID 15959853), "Effects of selegiline on antioxidant systems in the nigrostriatum in rat"; bibliographic data (title, journal, year, authors, PMID) was confirmed via an opened PubMed search-listing page, but the full abstract page itself could not be opened this session (repeated rate-limiting), so the specific antioxidant markers measured and the direction/magnitude of effect are not independently confirmed beyond the title and are not claimed here. Human, drug-specific, Tier A-eligible by title but inaccessible: Kushleika J, Checkoway H, Woods JS, Moon JD, Smith-Weller T, Franklin GM, Swanson PD. Ann Neurol. 1996 (PMID 8602757), "Selegiline and lymphocyte superoxide dismutase activities in Parkinson's disease," a human PD cohort measuring lymphocyte SOD activity. This article's abstract could not be opened after five separately-timed attempts across this session (repeated HTTP 429 responses from the target site and a bot-verification challenge page), so its sample size, direction, and magnitude could not be verified; it is disclosed here rather than used to support a grade above yellow.

Mechanism

Named, Tier B. Selegiline's propargylamine structure has documented free-radical-scavenging activity (directly demonstrated for selegiline itself in the Khaldy in vitro assay) independent of MAO-B inhibition, consistent with, and overlapping with, the mitochondrial-protective literature cited above (see Overlap map).

Counter-evidence held on record

No source located in this review shows selegiline raising oxidative-stress markers; the confirmed direction is protective. The human-cohort evidence that could resolve this more definitively (Kushleika 1996) could not be accessed this session and is disclosed as such, not treated as supportive. This is a protective, reverse-direction finding for the confirmed in vitro portion, not a nutrient deficiency, and must never be recast as one. No antioxidant supplementation is implied, needed, or supported by this entry.

Limits on what this shows

• Why no grade: This category was searched with "selegiline copper" against a PubMed search-listing page (10 results reviewed in full): all were either analytical-chemistry assay papers using copper-catalyzed click chemistry to detect selegiline in urine (unrelated to copper status), papers designing new selegiline-derivative compounds as Alzheimer's drug candidates that chelate copper/iron/zinc (these are novel compounds, explicitly not selegiline itself, and fail the Hard Rule 6 cohort test), or unrelated monoamine-oxidase biochemistry papers. A follow-up query ("selegiline ceruloplasmin serum copper") was attempted but blocked by repeated HTTP 429 rate-limiting before it could complete. No circulating consumer claim regarding selegiline and copper could be identified; a live consumer-web sweep (general search engines, supplement-retailer or nutrition-blog content) was not possible this session because this session's shared WebSearch budget was already exhausted and direct fetches of general search engines (DuckDuckGo, Mojeek) were refused under their own robots.txt policy.

Assessment

A genuine negative result from the one completed search, combined with an incomplete follow-up query due to rate limiting; disclosed as such rather than treated as a fully exhaustive clean gap. A future revision should re-attempt "selegiline ceruloplasmin," "selegiline serum copper," and the Europe PMC/Semantic Scholar/OpenAlex channels (all blocked at the proxy/gateway level, HTTP 403, during this review) for this category specifically.

Limits on what this shows

• Why no grade: This category was searched with "selegiline iron chelation brain" against a PubMed search-listing page (10 results reviewed in full). Every relevant hit describes selegiline's propargylamine chemical scaffold being used by the Youdim/Mandel research group as the starting point to design newer, different multifunctional drug candidates (ladostigil, M30) that are themselves potent iron chelators; none shows selegiline itself measurably altering serum iron, ferritin, or transferrin saturation, and the new compounds are not selegiline (fail the Hard Rule 6 cohort test). Brain iron accumulation in Parkinson's disease is well-documented disease-intrinsic pathology, not a selegiline effect, and is deliberately excluded from grading here per Hard Rule 2 rather than conflated with a drug effect. No circulating consumer claim regarding selegiline and iron (depletion or overload) could be identified; a live consumer-web sweep was not possible this session for the reasons stated under Copper above.

Assessment

A genuine negative result for selegiline-specific iron-status evidence, with the important caveat that the adjacent, disease-level and drug-design literature is real and extensive but does not pass the cohort test for selegiline itself; that distinction is the main finding of this entry. The Europe PMC, Semantic Scholar, and OpenAlex channels were not independently reachable for this category this session (HTTP 403 at the proxy/gateway level).

Limits on what this shows

• Why no grade: This category was searched with two direct phrasings against opened PubMed search-listing pages: "selegiline gut microbiome microbiota" and "selegiline intestinal bacteria," both returning zero results, the second explicitly confirmed by PubMed's own "no results were found" message. A broader class-level query, "monoamine oxidase inhibitor gut microbiota," surfaced one potentially relevant animal study, Tian Z, Wang X, Han T, et al. Nutrients. 2023 (PMID 37299505), "Inhibition of MAOB ameliorated high-fat-diet-induced atherosclerosis by inhibiting endothelial dysfunction and modulating gut microbiota," by the same author group (Tian, Wang, Han) that separately published a 2023 selegiline-specific metabolic study (Int Immunopharmacol, PMID 36822098, "Selegiline ameliorated dyslipidemia and hepatic steatosis in high-fat diet mice") found earlier in this review, raising the possibility selegiline itself was the MAOB inhibitor used in the Nutrients paper. The article page could not be opened after two separately-timed attempts (repeated HTTP 429 responses), so the drug identity and cohort could not be confirmed, and it is disclosed here as an unverified lead rather than used to support a grade. No circulating consumer claim regarding selegiline and gut microbiome could be identified; a live consumer-web sweep was not possible this session for the reasons stated under Copper above.

Assessment

Two genuine zero-result direct searches, combined with one specific, named, plausible lead that tooling access prevented confirming either way. This should be read as an incompletely resolved gap, not a fully clean negative; a future revision should prioritize re-opening PMID 37299505 to resolve whether selegiline itself was the study agent.

Limits on what this shows

• Key negative/null findings: None located; the gap is the direct-measurement gap itself, disclosed here rather than papered over with the adjacent membrane-potential findings.
• At-risk subgroups: Not established.

Regulatory status

Not addressed in the FDA/DailyMed labeling for either formulation.

Population evidence

Same preclinical sources as Mitochondrial burden: Szilagyi et al. 2009 (PMID 19332347); Paterson et al. 1998 (PMID 9453545); Simon et al. 2001 (PMID 11711036); Tatton and Chalmers-Redman 1996 (PMID 8959986); Tatton et al. 1996 (PMID 8988461); Ebadi et al. 2002 (PMID 11813232); shared origin disclosed in the Overlap map below. None of these studies report ATP content, ATP synthesis rate, or oxygen-consumption-based energy flux directly; all measure mitochondrial membrane potential and/or Bcl-2-family protein expression as their endpoint.

Mechanism

Inferred, not directly demonstrated. Preserved mitochondrial membrane potential is mechanistically upstream of ATP synthase function in standard mitochondrial physiology, but this review found no direct ATP measurement confirming that the inference translates into altered cellular energy output in selegiline-exposed tissue.

Counter-evidence held on record

No source located measures ATP content or synthesis rate in selegiline-exposed tissue in either direction; this entry rests entirely on mechanistic inference from the membrane-potential literature shared with Mitochondrial burden, and that inferential gap is stated plainly. This is an indirect, mechanistically inferred signal, explicitly weaker than Mitochondrial burden above it, and must not be read as a demonstrated energy-production benefit or as grounds for any energy-metabolism supplement claim (CoQ10, creatine, B vitamins, or similar). No supplementation is implied or recommended.

Limits on what this shows

• Why no grade: The EMSAM regulatory label provides a genuine, if indirect, Tier A data point: its clinical program showed "no clinically important changes in laboratory test parameters associated with EMSAM," which would include standard hematologic parameters. This is a real Tier A null signal, recorded here rather than silently omitted, but a null finding from general safety surveillance cannot itself satisfy the Tier B/C bar Step 7 requires for even a yellow grade, so it does not move this category above ungraded. A direct search, "selegiline hemoglobin hematocrit anemia," against an opened PubMed search-listing page returned zero results, explicitly confirmed by PubMed's "no results were found" message. A broader query combining "selegiline erythropoietin" and "oxygen consumption" did not surface any selegiline-specific result among those reviewed (the query syntax returned a very large, off-topic general result set rather than a targeted one, and was not pursued further given the clear absence of a relevant signal). No circulating consumer claim regarding selegiline and oxygen delivery, hemoglobin, or red-cell parameters could be identified; a live consumer-web sweep was not possible this session for the reasons stated under Copper above.

Assessment

A real, reassuring-but-not-dispositive null finding from the label's passive adverse-event surveillance, combined with two genuine negative/inconclusive literature searches. This should not be reworded as "selegiline is safe for oxygen delivery," only as "no hematologic signal was reported in the EMSAM clinical program, and no mechanistic literature linking selegiline to oxygen delivery or utilization was located."