Side-by-side · Research reference

PNC-27vsSS-31

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AAnimal-StrongHUMAN-REVIEWED18/41 cited

BPhase 3HUMAN-REVIEWED9/43 cited

PNC-27

p53-HDM-2 Peptide · Membrane-Targeting

32 AAPeptide lengthSarafraz-Yazdi 2022

12-26p53 domain

Pre-clinicalDevelopment stage

In vitro / Pre-clinical only

SS-31

Cardiolipin-binding · Mitochondrial protective

40 mgDaily doseSzeto 2014

Phase 3Evidence levelSzilagyi 2009 Szeto 2014

~3 hrHalf-life

SQ · Abdomen · Once daily

01Mechanism of Action

Parameter

PNC-27

SS-31

Primary target

Membrane-bound HDM-2 protein on cancer cell surfaceSarafraz-Yazdi 2022 Krzesaj 2024

Cardiolipin in inner mitochondrial membraneSzeto 2014

Pathway

PNC-27 binds to membrane HDM-2 1-109 domain → transmembrane pore formation → rapid necrosis (poptosis)Pincus 2024 Krzesaj 2024

Cardiolipin binding → cristae stabilisation → ETC integrity → reduced ROS + preserved ATP synthesisSzeto 2014 Szilagyi 2009

Downstream effect

Immediate cell lysis and extrusion of intracellular contents; secondary mitochondrial membrane disruptionPincus 2024 Krzesaj 2024

Mitochondrial bioenergetic preservation; cardio-, neuro-, and reno-protective effects in animal + clinical studiesSzeto 2014

Feedback intact?

N/A — cytotoxic mechanism, not signaling modulation

—

Origin

Chimeric design: p53 transactivating domain (12-26) fused to penetratin CPP sequenceSarafraz-Yazdi 2022

Synthetic tetrapeptide D-Arg-Dmt-Lys-Phe-NH₂; cell-permeable, mitochondrial-selectiveSzeto 2014

Antibody development

—

02Dosage Protocols

Parameter

PNC-27

SS-31

Clinical status

Pre-clinical only — no human trials

In vitro and animal model data only.

—

In vitro concentrations

10–100 μM range

Effective concentrations in cell culture studies.

—

Shorter analogue

PNC-28 (28 AA variant)

Retains HDM-2 binding and cytotoxic activity.

—

Evidence basis

Pre-clinical / In vitro

Multiple Phase 3 trials (Barth, AMD, ischemia-reperfusion)Szeto 2014 Szilagyi 2009

Standard dose

—

40 mg / day SQ (clinical trials)Szeto 2014

Anecdotal community range 5-10 mg/day. Phase 3 trials use 40 mg.

Frequency

—

Once daily

Lower / starter dose

—

5 mg / day (anecdotal)

Duration

—

Indefinite for mitochondrial disease; cycled for healthspan use

Reconstitution

—

Bacteriostatic water

Timing

—

Morning fasted preferred; pre-workout for exercise-induced mitochondrial stress

Half-life

—

~3 h plasma; tissue uptake longer

03Metabolic / Fat Loss Evidence

Parameter

PNC-27

SS-31

Fat loss mechanism

None — cytotoxic anticancer agent

—

04Side Effects & Safety

Parameter

PNC-27

SS-31

Human safety data

None available — no human trials conducted

—

Normal cell selectivity

In vitro: no cytotoxicity to normal cells (MCF-10-2A, peripheral blood mononuclear cells)Sarafraz-Yazdi 2010 Thadi 2020

Normal cells express minimal membrane HDM-2.

—

Cancer cell specificity

Depends on membrane HDM-2 expression levels

Ovarian cancer lines with low membrane HDM-2 showed <30% necrosis.

—

Cell death mechanism

Necrosis (not apoptosis) — rapid membrane lysisPincus 2024

—

Mitochondrial effects

Secondary mitochondrial membrane disruption in cancer cells

—

Injection site reaction

—

Erythema, mild pruritus

GI symptoms

—

Nausea (uncommon)

Headache

—

Reported in some Phase 3 trials

Cardiovascular

—

Cardio-protective in studies; no signal of harm

Long-term safety

—

Phase 3 data over 24+ months; no major safety signalsSzeto 2014

Pregnancy / OB

—

Avoid — insufficient data

Absolute Contraindications

PNC-27

·Human use — no clinical trials or safety data

SS-31

·Pregnancy / breastfeeding
·Hypersensitivity to peptide

Relative Contraindications

PNC-27

—

SS-31

·None established

05Administration Protocol

Parameter

PNC-27

SS-31

1. Pre-clinical status

PNC-27 has not been tested in human subjects. All data derive from in vitro cancer cell line studies and limited animal models. No approved clinical formulation, dosing protocol, or safety profile exists.Pincus 2024

Add bacteriostatic water per label. Light-protected handling.

2. Cell culture protocols

In vitro studies used 10–100 μM PNC-27 dissolved in cell culture medium. Peptide was added directly to cancer cell cultures (pancreatic, breast, colon, ovarian, leukemia lines) and incubated for 24–72 hours.

SQ — abdomen or thigh. Rotate sites.

3. Fluorescent labeling studies

Dual-labeled PNC-27 (green on N-terminus, red on C-terminus) demonstrated intact peptide binding to cancer cell membranes with combined yellow fluorescence at 30 minutes, persisting during cell lysis.Sookraj 2010

Morning fasted; pre-workout for exercise-augmented mitochondrial stress.

4. Membrane HDM-2 requirement

Cytotoxicity correlates directly with membrane HDM-2 expression levels. Blocking HDM-2's p53-binding domain (1-109) with monoclonal antibodies prevents PNC-27-induced necrosis.

Lyophilised: refrigerate, light-protected. Reconstituted: refrigerate ≤30 days.

5. Needle

—

29–31G, 4–8 mm insulin syringe.

06Stack Synergy

PNC-27

— no documented stacks

SS-31

+ MOTS-c

Moderate

View MOTS-c →

SS-31 and MOTS-c address mitochondrial decline through complementary axes. SS-31 protects existing mitochondrial structure (cardiolipin binding, cristae stabilisation). MOTS-c upregulates AMPK/PGC-1α, triggering biogenesis of new mitochondria. Together they pair preservation with renewal — anecdotally favoured in healthspan and post-cardio-event recovery protocols.

SS-31: 5–10 mg SQ · daily morning
MOTS-c: 5 mg SQ · 2× per week pre-workout
Primary benefit: Mitochondrial preservation + biogenesis