Genistein (4′,5,7-trihydroxyisoflavone) is a naturally occurring isoflavone, classified under the polyphenolic family of secondary metabolites. Structurally, it consists of a C15 skeleton with two aromatic rings (A and B) connected by a heterocyclic pyran ring (C) (Figure 1). This chemical arrangement confers estrogenic activity on genistein due to its similarity to 17β-estradiol, allowing it to bind to ERs [21, 33]. The hydroxyl groups at the 5, 7, and 4′ positions are critical for hydrogen bonding, radical scavenging, and receptor interaction. The molecule exhibits poor water solubility, moderate lipophilicity, and is predominantly found in soy as glycosides (e.g., genistin), which require enzymatic hydrolysis in the intestine to release the biologically active aglycone [8, 11].

One of the major limitations of genistein as a therapeutic agent is its low oral bioavailability. After ingestion, genistein glycosides are hydrolyzed in the gut to release the aglycone form, which undergoes absorption in the small intestine. However, genistein is subjected to first-pass metabolism in the liver, leading to glucuronidation, sulfation, and rapid systemic clearance, resulting in reduced plasma concentrations of the active compound [8, 11]. Inter-individual variability, influenced by gut microbiota composition, dietary factors, and genetic polymorphisms, further modulates its absorption and metabolism [8, 11].

To overcome these challenges, different formulation strategies have been explored, including nanoparticle encapsulation (nano-genistein or hybrid nanocarriers) to improve solubility and stability, lipid-based carriers (liposomes, phytosomes) to enhance intestinal absorption [9], and co-administration with bioenhancers such as piperine to slow metabolism [34].

The plasma half-life of genistein ranges between 6 and 8 hours, depending on dose and formulation [8]. It tends to accumulate in estrogen-responsive tissues (breast, prostate, uterus) as well as bone, liver, and brain, consistent with its pleiotropic biological activities. The balance between aglycone and conjugated metabolites determines its bioactivity at the cellular level [11].

Genistein structurally mimics 17β-estradiol, enabling it to bind to ERs. It displays a higher affinity for ERβ than for ERα, producing tissue-selective effects distinct from endogenous estrogens [1]. ERβ activation is associated with anti-proliferative, pro-apoptotic, and anti-inflammatory functions [1, 31]. Through ER signalling, genistein regulates the expression of genes involved in cell cycle control, apoptosis, and differentiation [15, 17].

This selective ER modulator (SERM)-like activity positions genistein as a potential alternative to hormone replacement therapy with reduced risk of carcinogenesis compared to synthetic estrogens [1, 15, 17].

Oxidative stress contributes significantly to the pathogenesis of inflammatory disorders, neurodegeneration, and cancer. Genistein enhances cellular defence via direct scavenging of ROS and reactive nitrogen species (RNS) [1]. It activates the Nrf2/ARE signalling axis, leading to the transcription of antioxidant genes such as heme oxygenase-1 (HO-1), glutathione peroxidase, and superoxide dismutase [6, 32]. Genistein also preserves mitochondrial function and prevents lipid peroxidation in stressed tissues [32]. By reinforcing redox homeostasis, it contributes to long-term cytoprotection [1, 6, 32].

Chronic inflammation is a central driver of multiple pathologies, including cancer. Genistein inhibits NF-κB signalling, resulting in reduced transcription of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) [1, 2, 9]. It also downregulates MAPK pathways [extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38], thereby modulating stress responses and cytokine production [1, 2], and suppresses the JAK/STAT pathway, relevant in cancer and autoimmune diseases [1, 9]. Genistein reduces inducible enzymes such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), limiting prostaglandin and nitric oxide production [1, 2, 9]. Collectively, these mechanisms prevent uncontrolled inflammation, which otherwise promotes tissue damage, fibrosis, and tumour progression (Figure 2).

Genistein inhibits cell proliferation by inducing cell cycle arrest at the G1/S and G2/M transitions. It upregulates CDK inhibitors such as p21^Cip1 and p27^Kip1, suppresses cyclin D1 and cyclin E expression, and blocks receptor tyrosine kinase signalling [epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR)], reducing MAPK/ERK and PI3K/Akt pathway activity [35]. In hormone-sensitive cancers, it also modulates ER-dependent signalling to reduce estrogen-driven proliferation [2, 36]. For apoptosis, genistein activates both intrinsic (mitochondrial) and extrinsic (death receptor) pathways. It upregulates pro-apoptotic proteins (Bax, Bad) while downregulating anti-apoptotic Bcl-2 and Bcl-xL, leading to cytochrome c release, caspase-9, and caspase-3 activation [37, 38]. It also enhances Fas/FasL signalling, promoting caspase-8 activation [38], and stabilizes p53, facilitating apoptosis under stress conditions [38]. Genistein suppresses NF-κB and activates Nrf2 responses, thereby reinforcing apoptosis while reducing oxidative damage [39].

These dual effects on proliferation and apoptosis highlight its promise as a chemopreventive and therapeutic agent, effective in preclinical models of breast, prostate, colon, and pancreatic cancers [40]. It may also enhance the sensitivity of tumours to chemotherapy and radiotherapy [1]. Beyond oncology, modulation of cell turnover and apoptosis may support tissue regeneration, aging, and inflammatory disorders [40, 41].

Emerging evidence identifies genistein as a potent epigenetic modulator. It influences DNA methylation by regulating DNA methyltransferase (DNMT) activity, leading to demethylation and reactivation of tumour suppressor gene promoters [28, 34, 42]. This reactivation restores critical regulatory pathways governing cell cycle arrest and apoptosis in cancer cells. Genistein also induces selective changes in global DNA methylation patterns in a context-dependent manner, modulating the transcriptional landscape through effects on both tumour suppressor genes and oncogenes [43, 44].

In addition to DNA methylation, genistein modulates histone post-translational modifications. It inhibits histone deacetylases (HDACs), resulting in increased histone acetylation and chromatin relaxation, thereby facilitating transcription of growth-inhibitory and pro-apoptotic genes [45]. Genistein further influences histone methyltransferases and demethylases, altering histone methylation marks that favour tumour suppressor gene expression and suppress oncogenic transcriptional programs [46, 47].

Genistein also regulates epigenetic networks through non-coding RNAs. It upregulates tumour-suppressive microRNAs (miRNAs), including miR-34a and the miR-200 family, while downregulating oncogenic miRNAs such as miR-21 and miR-155, thereby inhibiting proliferation, invasion, and chemoresistance [28, 48, 49]. Additionally, genistein modulates the expression of specific long non-coding RNAs involved in chromatin remodelling and transcriptional regulation, contributing to apoptosis induction and growth inhibition [50, 51].

Collectively, this epigenetic plasticity highlights genistein’s potential for long-term disease prevention and therapeutic intervention.

Genistein inhibits protein tyrosine kinase activity, particularly targeting EGFR and PDGFR [52–55]. Its interaction with growth factor signalling is concentration-dependent and context-specific, primarily investigated in cancer chemoprevention and therapeutic settings [56–58]. As a protein tyrosine kinase inhibitor, genistein suppresses phosphorylation and activation of EGFR and other ErbB family members, including HER2/ErbB2, thereby attenuating ligand-driven proliferative and survival signalling [52, 53, 59]. Genistein also inhibits insulin-like growth factor-1 receptor (IGF-1R) signalling and its crosstalk with ER pathways. At higher concentrations, tyrosine kinase inhibition predominates, resulting in anti-proliferative effects through concurrent blockade of ER- and GF-mediated signalling, whereas at lower concentrations, estrogenic activity may dominate. In ER+/HER2+ cells, low-dose genistein can paradoxically enhance cell proliferation by activating ER signalling and amplifying ER-HER2 crosstalk [60].

Genistein exerts potent anti-inflammatory effects through multifaceted molecular mechanisms, including suppression of NF-κB and MAPK pathways, activation of Nrf2 antioxidant defences, and regulation of Toll-like receptor (TLR) and inflammasome activity [1, 2, 6]. Genistein inhibits activation of NF-κB, a central transcription factor that regulates pro-inflammatory cytokines (TNF-α, IL-1β, IL-6). It prevents phosphorylation and degradation of IκBα, thereby reducing NF-κB nuclear translocation. This downregulation leads to decreased production of adhesion molecules (ICAM-1, VCAM-1) and inflammatory mediators [2, 6, 9, 15].

Genistein suppresses the MAPK pathways (ERK, JNK, and p38), which are crucial in cytokine production and immune cell activation [2, 6]. By attenuating MAPK signalling, genistein reduces inflammatory gene transcription and tissue damage. Genistein modulates TLR signalling, reducing the downstream inflammatory cascade triggered by pathogen-associated molecular patterns (PAMPs). It also inhibits activation of the NLRP3 inflammasome, thereby reducing caspase-1 activation and IL-1β/IL-18 secretion [12, 29]. In obesity and diabetes models, genistein reduces adipose tissue inflammation by lowering TNF-α and IL-6. It improves endothelial function by reducing vascular inflammation and oxidative stress [2, 6]. Genistein suppresses tumour-promoting inflammation in the tumour microenvironment, downregulates COX-2, iNOS, and pro-inflammatory cytokines, thereby limiting inflammation and disease progression (Table 2). In neurodegenerative disease models, genistein reduces microglial activation and cytokine release, protecting neurons from inflammation-induced apoptosis. Genistein decreases airway hyperresponsiveness and inflammatory cytokines in models of asthma and COPD. In tuberculosis and other infectious conditions, it modulates macrophage-mediated inflammatory responses [2, 6, 29].

Chronic inflammation is a key factor in the progression of autoimmune diseases, metabolic disorders, and cancer. Genistein demonstrates broad-spectrum anti-inflammatory activity. These mechanisms suggest that genistein could be developed as a nutraceutical or adjuvant therapy for chronic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, asthma, and COPD [6, 24].

The most extensively studied therapeutic application of genistein is its role in cancer prevention and therapy, due to its ability to modulate multiple cellular signalling pathways. It exhibits multiple effects (Figure 3), including regulation of cell proliferation, apoptosis, angiogenesis, metastasis, and epigenetic modifications [1, 2]. Unlike cytotoxic chemotherapy, genistein demonstrates a chemopreventive and chemosensitizing profile with relatively low toxicity, making it a promising candidate for integrative cancer therapy (Table 3) [3].

It inhibits cell proliferation by interfering with the cell cycle, particularly inducing arrest at the G2/M or G1 phase, downregulating cyclins (cyclin D1, cyclin E) and CDKs while upregulating cell cycle inhibitors (p21, p27) [53, 63]. It also suppresses growth factor receptor signalling, including EGFR and HER2, commonly overexpressed in cancers [2, 5].

Genistein induces apoptosis by activating intrinsic (mitochondrial) and extrinsic (death receptor) apoptotic pathways. It enhances pro-apoptotic proteins (Bax, Bak) and decreases anti-apoptotic proteins (Bcl-2, Bcl-xL), and activates caspase cascades, leading to programmed cell death [6].

It inhibits the expression of VEGF (vascular endothelial growth factor) and HIF-1α, key mediators of tumour angiogenesis, and shows anti-angiogenic activity. It suppresses endothelial cell proliferation and migration, reducing neovascularization in tumours [53].

Anti-metastatic properties have been identified when it downregulates matrix metalloproteinases (MMP-2, MMP-9) that degrade the extracellular matrix. It reduces epithelial-to-mesenchymal transition (EMT) by restoring E-cadherin expression and limits tumour invasion and metastatic spread [8]. It also acts as a DNA methylation modulator, reactivating silenced tumour suppressor genes, modulating histone acetylation and miRNA expression, contributing to long-term chemopreventive effects [9, 11].

As previously discussed, genistein’s modulation of key oncogenic pathways suppresses NF-κB, PI3K/Akt, and MAPK pathways, reducing pro-survival and inflammatory signalling. It enhances p53 activity, promoting apoptosis and DNA repair. In hormone-dependent cancers, genistein acts as a phytoestrogen, binding to ERβ and modulating ER signalling [12].

In breast cancer studies, it exhibits dual estrogenic/anti-estrogenic effects depending on the hormonal context. In ER-positive breast cancer, genistein competes with estradiol, potentially lowering estrogen-driven proliferation, and sensitizing breast cancer cells to tamoxifen and other endocrine therapies [58].

It inhibits androgen receptor signalling and prostate-specific antigen (PSA) expression, reducing tumour growth and angiogenesis in prostate cancer models [53].

It has also been reported that, in lung and gastrointestinal cancers, it suppresses EGFR-mediated proliferation in non-small cell lung cancer (NSCLC) and reduces COX-2 and inflammatory mediators in colorectal and gastric cancers [64].

In pancreatic cancer, it inhibits NF-κB and STAT3 signalling, reducing cancer stem cell populations and enhancing the efficacy of gemcitabine and other chemotherapeutic agents [53].

Epidemiological studies link high soy consumption with lower incidence of hormone-dependent cancers such as breast, prostate, and endometrial cancers [3, 5]. Preclinical models also support genistein’s efficacy against gastrointestinal, lung, and pancreatic cancers [2, 15].

Metabolomics allows the identification and quantification of genistein and its metabolites in biological systems, offering a detailed view of its bioavailability and metabolic fate. Genistein undergoes extensive phase II metabolism, generating glucuronide and sulfate conjugates detectable in plasma and urine [8, 11]. Advanced metabolomics studies have revealed tissue-specific accumulation patterns and inter-individual variability in metabolism [11]. Comparative studies in populations with high vs. low soy intake have correlated genistein-derived metabolites with reduced cancer risk and improved cardiometabolic profiles [3]. Metabolomics thus bridges dietary intake with personalized health responses to genistein.

Genistein influences global gene expression through ER-dependent and ER-independent pathways. Transcriptomic profiling (RNA-seq, microarrays) has identified downregulation of oncogenes (e.g., c-Myc, cyclin D1) in cancer cells [41], upregulation of tumour suppressor genes (e.g., p21, PTEN), modulation of immune-related genes leading to reduced pro-inflammatory cytokine expression [2], and regulation of metabolic gene networks associated with glucose homeostasis and lipid metabolism [25]. These transcriptomic signatures demonstrate how genistein exerts multi-targeted therapeutic effects.

Proteomics has uncovered genistein’s impact at the protein expression and signalling level through its tyrosine kinase inhibition activity. Genistein alters phosphorylation states of proteins downstream of EGFR, PDGFR, and VEGFR [52, 53, 55]. Proteomic data also show increased expression of pro-apoptotic proteins (Bax, caspase-3) and decreased anti-apoptotic proteins (Bcl-2, survivin) [41]. NF-κB subunits, COX-2, and iNOS are consistently suppressed following genistein exposure [2]. This proteomic evidence complements transcriptomic findings, validating the mechanistic pathways of genistein action.

Epigenomic studies highlight genistein’s ability to reprogram cellular states without altering DNA sequence. Genistein modulates promoter methylation of tumour suppressors such as p16 and BRCA1 [42–45]. It influences histone acetylation and methylation, altering chromatin accessibility for transcription [43]. Genistein has been shown to regulate oncogenic and tumour-suppressive miRNAs, including miR-21, miR-155, and let-7 family members [46, 48, 49]. These epigenetic effects support the concept of genistein as a nutritional epigenetic modulator with implications for cancer prevention and therapy.

Recent studies increasingly employ multi-omics integration, combining metabolomics, transcriptomics, and proteomics to capture a holistic view of genistein’s biological actions. Such approaches have identified network-level interactions, showing how genistein simultaneously regulates oxidative stress, inflammation, and proliferation. Systems biology modelling, supported by omics data, predicts genistein’s synergistic effects with conventional drugs, providing a framework for host-directed and precision therapies [1, 6, 9].