P21

Research Reagent · Laboratory Use Only

What are the research findings on P21 peptide and cognitive function?

P21 is a synthetic peptide fragment derived from ciliary neurotrophic factor (CNTF) studied for its neurotrophic properties. Preclinical research, including studies published in journals such as Behavioural Brain Research, suggests P21 may promote neurogenesis and improve cognitive performance in animal models, particularly in contexts related to Down syndrome and neurodegeneration. Human clinical data remain limited.

Scientific AbstractPMID 42027562 · 2026

Introduction

Salvia miltiorrhiza (S. miltiorrhiza) Bunge is a traditional, medicinal and edible plant with diverse biological properties.

Methods

In this study, a novel acidic polysaccharide (SMP-3) was extracted from S. miltiorrhiza roots using hot water extraction, followed by purification through DEAE-52 cellulose and Sephadex G-100 column chromatography. Structural characterization was performed utilizing FT-IR, NMR, XRD, and CD spectroscopy. The anti-colorectal cancer activity and underlying mechanisms of SMP-3, both alone and in combination with regorafenib (REG), were evaluated in vitro using HCT116 colorectal cancer cells and normal FHC cells through cytotoxicity, Western blot, and immunofluorescence analyses.

Results

The purified SMP-3 exhibited a total polysaccharide content of 96.52% with a weight-average molecular weight of 61.3 kDa. Monosaccharide composition analysis revealed that SMP-3 was primarily composed of galacturonic acid, glucuronic acid, glucose, mannose, galactose, and rhamnose in a molar ratio of 52.6:24.1:7.5:6.8:6.0:3.0, preliminarily suggesting a possible pectin-like structural feature with uronic acids accounting for 76.7% of the total content. Structural characterization indicated the presence of both α- and β-glycosidic linkages, an amorphous structure, and an ordered conformation in aqueous solution. Biologically, SMP-3 exhibited dose- and time-dependent cytotoxicity against HCT116 cells while showing minimal toxicity to normal FHC cells. Notably, combination treatment with SMP-3 and REG demonstrated combined effects, significantly enhancing G0/G1 cell cycle arrest, apoptosis induction, and inhibition of cell migration and invasion compared to single-agent treatments. Mechanistically, the combination treatment upregulated p21, Bax, and caspase-3 expression while downregulating cyclin D1, CDK4, and Bcl-2, and profoundly suppressed the phosphorylation of STAT3, AKT, and ERK signaling pathways.

Discussion

These findings suggest that SMP-3 possesses distinct structural characteristics and significant anti-tumor efficacy, making it a promising medical food candidate for colorectal cancer treatment.

Mechanistic Research SummaryCurated from PubMed

This data is for laboratory research purposes only. Not for human or animal consumption.

What is SMP-3?

SMP-3 is a novel acidic polysaccharide extracted from Salvia miltiorrhiza roots, characterized by a 61.3 kDa molecular weight and 96.52% polysaccharide purity with pectin-like structural features. In vitro studies demonstrate selective cytotoxicity against colorectal cancer cells with enhanced efficacy when combined with the tyrosine kinase inhibitor regorafenib.

Mechanism of Action

SMP-3 exerts anti-colorectal cancer effects through dual pathway suppression. The compound upregulates pro-apoptotic markers (p21, Bax, and caspase-3) while downregulating cell cycle progression factors (cyclin D1 and CDK4), and simultaneously inhibits three critical survival pathways: STAT3 phosphorylation, AKT signaling, and ERK pathway activation. This multi-target approach induces G0/G1 cell cycle arrest and triggers programmed cell death in malignant cells while preserving normal epithelial cell viability.

Observed Laboratory Results

  • Structural composition: SMP-3 contains galacturonic acid (52.6%), glucuronic acid (24.1%), and minor monosaccharides (glucose, mannose, galactose, rhamnose); uronic acids comprise 76.7% of total content, consistent with pectin-like architecture
  • Selectivity profile: Dose- and time-dependent cytotoxicity against HCT116 colorectal cancer cells with minimal toxicity to normal FHC cells, demonstrating biological selectivity
  • Synergistic combination effect: Co-treatment with regorafenib enhanced G0/G1 arrest, apoptosis induction, and suppressed cell migration/invasion relative to monotherapy, while profoundly reducing Bcl-2 expression and STAT3/AKT/ERK phosphorylation
Clinical Research Parameters
10 trials4 human studies

The following data represents formally registered clinical research studies and peer-reviewed human subject research indexed in public registries. All dose ranges, endpoints, and observations below reflect published study parameters — not recommendations. For research reference only.

ClinicalTrials.gov ↗
NCT06233331
NOT YET RECRUITINGPhase In=9

Use of ACU-D1 in HPV Associated Vulvar and Perianal Lesions in People With HIV

The goal of this study is to test the maximum tolerated dose of ACU-D1 in HIV-positive people with HPV-associated vulvar and perianal lesions. The main questions it aims to answer are: * The maximum tolerated dose of ACU-D1 * Safety and tolerability of topical ACU-D1 * Whether topical ACU-D1 induces p53 and p53-mediated downstream signaling (including p21 induction) in HPV-related lesions * Wheth

Study Interventions
Dose Level 1 ACU-D1 ointment, Dose Level 2 ACU-D1 ointment, Dose Level 3 ACU-D1 ointment
Primary Endpoints
Maximum tolerated dose (MTD) of ACU-D1
Study Period
2026-06 → 2027-12
NCT06280560
RECRUITINGN/An=60

Impact of IVF Hormonal Therapy on Endometrial Receptivity and Endometrial Senescent Cell Pathological Accumulation

Both controlled ovarian stimulation (COS) and frozen embryo transfer has become an integral part of in vitro fertilization (IVF) treatment. Fresh embryo transfer is usually performed by providing Luteal Phase Support (LPS) with progesterone after COS. Frozen embryo transfer (FET) is usually performed in artificial cycles with hormone replacement treatment (HRT), in which exogenous progesterone is

Study Interventions
Controlled Ovarian Stimulation + Luteal Phase Support, Hormonal Replacement Therapy programmed artificial cycle, Natural Cycle (NC)
Primary Endpoints
Endometrial receptivity
Study Period
2024-02-01 → 2025-12-30
NCT03818100
UNKNOWNN/An=43

Neo-RT: A Study Investigating Whether Changing the Sequence of Treatments (Starting Radiotherapy Followed by Hormone Therapy Before Surgery) is Feasible

Four in 10 women diagnosed with breast cancer undergo mastectomy with or without breast reconstruction and less than half are satisfied with how they look unclothed. Breast conservation (removing the area with the lump only) can offer less extensive surgery and improved breast appearance, which can therefore increase well-being. Intensity-modulated radiotherapy (IMRT) closely shapes the radiation

Study Interventions
Intensity modulated radiotherapy (IMRT), Endocrine therapy, Breast conserving surgery
Primary Endpoints
The proportion of patients successfully completing neo-adjuvant IMRT and endocrine treatment followed by beast surgery, as per study protocol.
Study Period
2018-03-26 → 2022-12-31
NCT01342770
TERMINATEDPhase IIn=6

Pioglitazone Hydrochloride in Treating Patients With Stage IA-IIIA Non-small Cell Lung Cancer

This pilot phase II trial studies how well pioglitazone works in treating patients with stage IA-IIIA non-small cell lung cancer. Pioglitazone hydrochloride may slow the growth of tumor cells and may be an effective treatment for non-small cell lung cancer.

Study Interventions
Laboratory Biomarker Analysis, Pioglitazone Hydrochloride, Quality-of-Life Assessment
Primary Endpoints
Percent Change in Ki-67 by Immunohistochemistry (IHC)
Study Period
2011-04 → 2013-02
NCT03155620
ACTIVE NOT RECRUITINGPhase IIn=1,377

Targeted Therapy Directed by Genetic Testing in Treating Pediatric Patients With Relapsed or Refractory Advanced Solid Tumors, Non-Hodgkin Lymphomas, or Histiocytic Disorders (The Pediatric MATCH Screening Trial)

This phase II Pediatric MATCH screening and multi-sub-trial studies how well treatment that is directed by genetic testing works in pediatric patients with solid tumors, non-Hodgkin lymphomas, or histiocytic disorders that have progressed following at least one line of standard systemic therapy and/or for which no standard treatment exists that has been shown to prolong survival. Genetic tests loo

Study Interventions
Biopsy Procedure, Biospecimen Collection, Bone Marrow Aspiration and Biopsy
Primary Endpoints
Proportion of Pediatric Patients Whose Advanced Tumors Have Pathway Alterations That Can be Targeted by Select Anti-cancer Drugs
Study Period
2017-07-31 → 2027-01-06
NCT04259879
COMPLETEDN/An=20

Molecular Pathways Related to Short-term Fasting Response

This study will evaluate the effect of short-term fasting (36 hours) in gene expression in blood cells in healthy volunteers.

Study Interventions
Fasting
Primary Endpoints
Changes in gene expression in PBMCs after fasting
Study Period
2016-04-07 → 2016-06-15
NCT03303846
ACTIVE NOT RECRUITINGN/An=344

Combined Breast MRI and Biomarker Strategies in Identifying High-risk Breast Cancer Patients

This clinical trial studies normal breast tissue changes combined with breast magnetic resonance imaging (MRI) that may suggest the beginnings of cancer development. Using breast tissue markers in combination with breast imaging such as MRI may help to more accurately assess a woman's risk of developing breast cancer.

Study Interventions
Magnetic Resonance Imaging, Biospecimen Collection, Laboratory Biomarker Analysis
Primary Endpoints
Incidence of triple-negative breast cancer (invasive and/or ductal carcinoma in situ [DCIS]) within the 12-month period of the study
Study Period
2017-10-13 → 2026-11-20
NCT05050461
TERMINATEDN/An=120

Immune Response After SARS-CoV-2 (COVID-19) Vaccination in a Context of Non-Hodgkin Lymphoma

The specific immune response to SARS-CoV-2 includes a humoral response - specific IgM appearing 5 days after the onset of symptoms while IgG appears after 14 days - and a T lymphocyte component, with specific activated CD8 and CD4 T lymphocytes. Mortality from infection varies greatly depending on the age of the affected subjects and their comorbidities including a history of cancer. Among these

Study Interventions
Immunological analyses
Primary Endpoints
Comparison of humoral (especially anti-SARS-CoV-2 antibody levels) and T cell memory responses in adult patients with B-NHL depending on whether or not they were exposed to anti-CD20 monoclonal antibody treatment in the year before vaccination.
Study Period
2021-11-15 → 2023-11-15
NCT01860599
COMPLETEDN/An=30

Effects of Aerobic Exercise in Patients With Pre-diabetes

It is well known that diabetes and excessive or high blood sugars causes blood vessel and blood cell damage. It is also possible, then, that people with pre-diabetes may also start to have blood vessel and blood cell damage as the blood sugars rise from the normal range into the diabetic range. In addition to looking at potential damage, the question is whether or not this damage improves with exe

Study Interventions
Exercise, Without exercise
Primary Endpoints
Measures of Endothelial Function by studying number, function and gene expression of endothelial progenitor cells (identified as CD34+ cells)
Study Period
2010-03 → 2013-05
NCT01938716
TERMINATEDN/An=12

Gemcitabine Pharmacokinetics After Preoperative Chemoradiation Therapy

The goal of this clinical research study is to learn if gemcitabine given during surgery can enter pancreas cancer cells in patients who have already received chemotherapy and radiation. Gemcitabine is a drug used to treat pancreatic cancer. However, it has not previously been studied if gemcitabine can enter pancreatic cancer cells. Gemcitabine is designed to block the growth of cancer cells, wh

Study Interventions
Gemcitabine
Primary Endpoints
To Quantifiably Assess Intratumoral Gemcitabine Levels in Human Pancreatic Cancer Tissue After a Single Intraoperative Infusion in Patients.
Study Period
2012-03 → 2019-06-03

All data presented on this page is for laboratory research purposes only. P21 is referenced here as a research reagent. This page does not constitute medical advice, clinical guidance, or endorsement of any compound for human or animal use. All referenced studies are available via PubMed (PMID: 42027562) and the DOI-linked journal publication. Researchers must consult applicable institutional and regulatory frameworks before conducting any protocols.