Research Advances and Prospects on Chemical Constituents,Pharmacological Effects,and Continuous Cropping Obstacles of Pseudostellaria heterophylla (Miq.) Pax

Abstract

Pseudostellaria heterophylla (Miq.) Pax, a medicinal herb from the Caryophyllaceae family, is known for its pharmacological properties, including its ability to replenish qi and strengthen the spleen. It contains active compounds such as cyclopeptides, polysaccharides, alkaloids, and saponins. Pharmacological research has revealed these compounds’ significant roles in immunomodulation, anti-inflammatory, antidiabetic, anticancer effects, myocardial protection, and intestinal repair. Currently, the P. heterophylla industry is constrained by challenges associated with continuous cropping obstacles. Contributing factors include soil acidification, microbial imbalance, and the build-up of autotoxic substances. Mitigation strategies include fallowing, soil sterilization, using microbial fertilizers, and crop rotation. This review offers valuable insights for advancing the development of P. heterophylla compounds and optimizing its cultivation techniques.

1. Introduction

Pseudostellaria heterophylla (Miq.) Pax ex Pax et Hoffm., a herbaceous species from the Caryophyllaceae family, is traditionally used both as a medicinal herb and edible plant, classified as a tonifying Chinese medicinal material. Its dried tuberous root is noted pharmacologically for its capabilities to replenish qi, fortify the spleen, promote fluid production, and moisten the lungs. Clinically, it is frequently prescribed to alleviate symptoms associated with qi-yin deficiency, including palpitations, shortness of breath, spontaneous sweating, thirst, and dry cough. Due to its mild medicinal properties and its tonifying effects without causing dryness, it is particularly suitable for children, the elderly, and convalescents post-illness. ¹ Recent studies indicate that P. heterophylla contains various bioactive compounds with significant pharmacological effects such as immunomodulation, anti-inflammatory actions, glucose regulation, anticancer activities, myocardial, and intestinal protection.^1,2 Figure 1 summarizes the key pharmacological effects and applications of P. heterophylla.

Figure 1.

Schematic diagram of the pharmacological effects and applications of P. heterophylla

Using bibliometric analysis, we integrated core themes in P. heterophylla research and developed a keyword co-occurrence network analysis map (Figure 2). This map identifies P. heterophylla as a dynamic, diverse research area, covering varied aspects such as bioactive components (e.g., polysaccharides, saponins), molecular mechanisms (gene expression, signaling pathways), pharmacological effects (anti-inflammatory, anticancer, immunomodulatory), cultivation physiology, environmental responses, traditional uses, quality improvement, and emerging analytical methods. The distinct vocabulary clusters in the map clearly illustrate the comprehensive knowledge structure of the field, highlighting current research hotspots and trends.

Figure 2.

Keyword co-occurrence network analysis map for P. heterophylla research

Current research on P. heterophylla, however, is fragmented and lacks systematic integration, particularly in structural characterization of components, pharmacological mechanisms, and quality control. To bridge these gaps, this paper extensively reviews and critically evaluates both domestic and international literature. It aims to systematically summarize the chemical structure, pharmacological effects, and mechanisms of P. heterophylla, and investigates the obstacles to continuous cropping that affect its cultivation. This work serves as a comprehensive guide for future research on the components and pharmacological activities of P. heterophylla and provides a theoretical foundation for developing its derivative products.

2. Research Overview

In this study, a keyword co-occurrence network analysis map for the P. heterophylla research field was generated using VOSviewer software. Literature searches were conducted across multiple Chinese and English databases, including Web of Science, PubMed, Google Scholar, Baidu Scholar, and China National Knowledge Infrastructure (CNKI), to ensure comprehensive coverage of relevant publications.

Scientific illustrations in this work were generated with the BioRender platform (https://BioRender.com). Structural information for chemical compounds was extracted based on detailed descriptions found in published Chinese and English academic literature and verified and supplemented using Blue Book on the Development of the Zherong Pseudostellaria heterophylla Industry (2022-2025). ³ Visualization of chemical structures was performed using the InDraw software.

3. Chemical Constituents

Up to now, a variety of chemical constituents have been identified and isolated from P. heterophylla, such as cyclic peptides, polysaccharides, alkaloids, saponins, amino acids, fatty acids, and trace elements. Specifically, cyclic peptides, polysaccharides, alkaloids, and saponins are the signature bioactive compounds in P. heterophylla.^4,5

3.1. Cyclic Peptides

Cyclic peptides (CPs) are polypeptides with a cyclic structure, formed through peptide bonds linking multiple amino acids. Unlike linear peptides, CPs display markedly different physicochemical properties, such as increased hydrophobicity, oxidative stability, and proteolytic resistance. This enhancement results from the cyclic structure shielding the N- and C-termini.^6,7 In 1991, Tan Ninghua’s research team fortuitously isolated two cyclic peptide compounds, Heterophyllin A and Heterophyllin B, from P. heterophylla. In 1993, they elucidated these compounds’ molecular structures using various techniques such as chemical, spectral, and enzymatic methods. This study was the first to reveal P. heterophylla’s cyclic peptide constituents, establishing a foundation for future research on these components.^8,9 In 1995, the team isolated another compound, Heterophyllin C, from P. heterophylla. ¹⁰ Subsequent studies led to the identification, isolation, and characterization of additional cyclic peptides, Heterophyllins D-J, from this species. ⁹ In 1994, Professor Morita isolated three cyclic peptide molecules, termed Pseudostellarins A-C, from the roots of P. heterophylla. The isolation procedure began with methanol extraction, followed by n-butanol partitioning of the crude extract. The extract was subsequently subjected to gradient elution over Diaion HP-20 macroporous resin, followed by silica gel column chromatography purification, and isolated using High-performance liquid chromatography (HPLC). ¹¹ Using the same method, Professor Morita then isolated Pseudostellarins D-H.^12-14 Recently, Zhao et al. (2022) successfully isolated two novel cyclic peptides, Pseudostellarin K and Pseudostellarin L, from the fibrous roots of P. heterophylla.^15,16 To date, 19 cyclic peptides have been identified in P. heterophylla (Figure 3).

Figure 3.

Structures of 19 cyclic peptides identified in P. heterophylla

3.2. Polysaccharides

Polysaccharides, ubiquitous in animals, plants, and microorganisms, are natural macromolecular carbohydrates consisting of monosaccharide units linked by glycosidic bonds. Systematic research on P. heterophylla polysaccharides began in the 1980s using water extraction and alcohol precipitation methods to initially isolate crude polysaccharides. In 1993, Chinese researchers isolated two homogeneous glucans, PHP-A and PHP-B, each composed solely of glucose units. This isolation involved boiling water extraction, removal of free proteins, dialysis, precipitation, and purification using DEAE-cellulose and Sephadex G-100 column chromatography. ¹⁷ Hu further fractionated the crude polysaccharides into three components with distinct molecular weights (PF40, PF60, PF90) based on varying ethanol concentrations used for precipitation. ¹⁸ Subsequent purification of semi-refined polysaccharide PF40 using sequential DEAE-cellulose 52 column chromatography and Sephacryl S-300 gel filtration chromatography yielded a novel polysaccharide, H-1-2. ¹⁹ Employing the same methods, Yang isolated another distinct polysaccharide, HPh-1-1. ²⁰ Following deproteinization, the extracted crude polysaccharide solution underwent two rounds of DEAE-Cellulose 52 column chromatography, isolating a pectic polysaccharide named 0.5MSC-F. ²¹ Furthermore, Polysaccharide PHP was obtained through water extraction and alcohol precipitation, followed by purification using gel chromatography. ²² Over three decades, research on P. heterophylla polysaccharides has advanced from basic extraction to a comprehensive exploration, encompassing structural characterization, pharmacological mechanisms, and application development. Table 1 presents the monosaccharide composition of commonly encountered polysaccharides in P. heterophylla.

Table 1.

Monosaccharide Composition of Polysaccharides From P. heterophylla

Polysaccharides	Monosaccharide composition
PHP-A	Glucose
PHP-B	Glucose
PF40	Galacturonic acid, Glucose, Galactose, Arabinose
PF60	Galacturonic acid, Glucose, Galactose, Arabinose
PF90	Galacturonic acid, Glucose, Galactose, Arabinose
H-1-2	Glucose
HPh-1-1	Glucose
0.5MSC-F	Rhamnose, Galactose, Arabinose, Galacturonic acid
PHP	Rhamnose, Galacturonic acid, Glucose, Galactose, Arabinose, Fucose

3.3. Alkaloids

Alkaloids are a class of nitrogen-containing organic compounds prevalent throughout the plant kingdom, characterized by complex cyclic structures like heterocycles (e.g., pyridine, quinoline, indole, and purine) and notable biological activities. In the Caryophyllaceae family, β-carboline alkaloids are prevalent. Four β-carboline alkaloids, Stellarine A and Pseudosterins A-C, have been identified in P. heterophylla (Figure 4). Stellarine A was the first to be isolated from the genus Pseudostellaria. ¹⁵ Pseudosterins A-C mainly differ in their substituent groups at the C-1 or C-3 positions. ²³ Additionally, P. heterophylla contains a variety of nucleoside constituents including guanosine, inosine, cytidine, thymidine, and uridine.

Figure 4.

Chemical structures of four alkaloids found in P. heterophylla

3.4. Saponins

Saponins are a class of naturally occurring glycosides extensively found in plants. They consist of an aglycone (genin) core linked to sugar chains through glycosidic bonds, which imbue them with unique chemical properties and diverse biological functions. Saponins are primarily classified into triterpenoid and steroidal types based on their aglycone structures. To date, six saponins have been isolated and characterized from P. heterophylla (Figure 5). Employing solvents of increasing polarity (petroleum ether, chloroform, ethyl acetate, and n-butanol), Wang et al processed the 75% ethanol extract of P. heterophylla through fractional extraction and subsequent column chromatography. This process yielded five saponins: Pseudotellarinoside A, Acutifoliside D, Daucosterol, β-sitosterol-3-O-β-D-glucoside-6′-O-palmitate, and Δ⁷-stigmastenol-3-O-β-D-glucoside (Pseudotellarinoside A and Acutifoliside D are pentacyclic triterpenoid saponins, while the remaining three are steroidal saponins).^24,25 Subsequently, Qin et al. applied ethanol reflux extraction to dried P. heterophylla tuberous roots, followed by sequential extraction using petroleum ether and ethyl acetate, treatment with macroporous resin, and silica gel column chromatography. This resulted in the initial isolation and characterization of an additional steroidal saponin, α-spinasterol-3-O-β-D-glucoside, from P. heterophylla.^2,26

Figure 5.

Chemical structures of six saponins found in P. heterophylla

4. Pharmacological Effects

4.1. Immunoregulatory Activity

Extensive research has shown that multiple components of P. heterophylla modulate the immune system. In 2000, Liu et al. reported that total saponins extracted from P. heterophylla enhanced endurance, hypoxia tolerance, and cold resistance in mice. Furthermore, these saponins improved the functionality of immune organs and the activity of immune cells. ²⁷ Yang identified the immunomodulatory properties of Pseudostellaria heterophylla peptide (PHP). PHP increases intracellular Ca²⁺ levels in splenic lymphocytes, which activates Calcineurin (CaN). Once activated, CaN dephosphorylates Nuclear Factor of Activated T Cells c1 (NFATc1), enabling nuclear translocation. This sequence triggers cytokine secretion, including IFN-γ, TNF-α, and IL-10, thus regulating the Th1/Th2 immune balance. These results underscore PHP’s potential as an immune-boosting functional food ingredient. ²⁸ The team subsequently isolated two immunomodulatory peptides, YG-9 and RP-5, from P. heterophylla protein hydrolysates. YG-9 binds to TLR2/TLR4 receptors on RAW264.7 macrophages, thereby activating the NF-κB signaling pathway. This activation leads to rapid phosphorylation and degradation of the inhibitory protein IκB-α, consequently releasing the free NF-κB p65 subunit. Ultimately, this process enhances the secretion of inflammatory mediators such as TNF-α, NO, and ROS, and stimulates murine splenic lymphocyte proliferation. However, RP-5 primarily activates the NF-κB pathway by binding to TLR2. Both peptides exert immunostimulatory effects through the TLR-NF-κB inflammatory axis, differing primarily in their receptor subtype selectivity.^29,30 Polysaccharides from P. heterophylla alleviate chronic fatigue syndrome in mice by modulating neuroendocrine functions, indicated by increased serum corticosterone levels, and enhancing immune function through the regulation of T lymphocyte subsets and immune organ functionality. This ultimately reduces fatigue symptoms, improves learning capacity, and ameliorates multisystem dysfunction. ³¹ Radix Pseudostellariae fibrous root polysaccharides (RPFRP) enhance immunity in immunocompromised mice via multiple mechanisms. Mechanisms include enhanced status of immune organs, increased macrophage phagocytosis, lymphocyte activation, and modulation of immune factors. ³² Cyclophosphamide (Cyp), an anticancer drug, impairs immune function. However, the P. heterophylla polysaccharide PF40 counteracts this immunosuppression by modulating immune organs, blood cells, lymphocyte subsets, and gut microbiota, thus restoring immune competence. ³³

When the immunomodulatory activity of P. heterophylla polysaccharides is insufficient, specific treatments are available to enhance it. For instance, ultrasonic treatment can increase the solubility and expose bioactive groups of P. heterophylla polysaccharides, thereby significantly enhancing both in vitro antioxidant capacity and in vivo immunomodulatory functions in mice. ³⁴ Furthermore, selenylation modification of Pseudostellariae Radix polysaccharides (RPP) significantly enhances their immunoprotective activity against cyclophosphamide (Cyp)-induced immune injury. This increased protective efficacy is attributed to structural alterations induced by selenylation, which presumably enhance the binding of the selenized polysaccharide (sRPP) to receptors on immune cells. ³⁵ Overall, P. heterophylla contains saponins, peptides, and polysaccharides that enhance immune organ function and immune cell activity via CaN/NFAT and TLR–NF-κB pathways. Processing methods such as ultrasonication and selenylation can further strengthen these immunomodulatory effects, including protection against drug-induced immunosuppression.

4.2. Anti-inflammatory Activity

P. heterophylla extracts have demonstrated significant anti-inflammatory effects. In treating atopic dermatitis (AD), P. heterophylla extract alleviates symptoms like skin erythema, pruritus, and thickening by downregulating the mRNA expression of cytokines such as IFN-γ, IL-4, and IL-6, modulating the hyperactivity of Th1/Th2 cells. Additionally, this extract suppresses the NF-κB and MAPK signaling pathways, reducing the release of inflammatory factors. ³⁶ Chronic obstructive pulmonary disease (COPD), a prevalent severe pulmonary disorder, can be mitigated with P. heterophylla extracts. The cyclic peptide extract (CPE) of P. heterophylla ameliorates pulmonary inflammation and respiratory function in COPD model rats by modulating inflammatory pathways. Specifically, CPE inhibits the TLR4/MyD88 signaling pathway, suppresses the phosphorylation of downstream proteins such as p-JNK, p-p38, and p-TAK1, thereby reducing TNF-α release and increasing anti-inflammatory IL-10 levels. This process alleviates lung tissue inflammation and alveolar damage. ³⁷ Similarly, the ethyl acetate extract of P. heterophylla alleviates pulmonary inflammation, enhances breathing, and mitigates smoking-induced lung function decline by inhibiting the release of pro-inflammatory factors like IL-8 and TNF-α. ³⁸ The cyclic peptide HB from P. heterophylla exhibits potential anti-inflammatory activity by suppressing the PI3K/Akt pathway. This inhibition reduces lipopolysaccharide (LPS)-induced generation of inflammatory mediators such as NO, IL-6, IL-1β, and reactive oxygen species (ROS), thereby attenuating inflammation, oxidative stress, and apoptosis. ³⁹ Furthermore, HB ameliorates colitis by activating the AMPK signaling pathway, which repairs the intestinal mucosal barrier and reduces inflammation. Concurrently, it remodels the gut microbiota, promoting beneficial bacteria and inhibiting harmful bacteria. ⁴⁰ In murine models, PHP significantly upregulates TLR4 protein expression in RAW264.7 cells, inhibits NF-κB-mediated secretion of pro-inflammatory factors, and alleviates intestinal inflammation. ²² Rat studies indicate that PHP enhances intestinal health and immune function through multiple mechanisms: it regulates gut microbiota by decreasing the Firmicutes/Bacteroidota ratio, increasing populations of Lactobacillus and Alloprevotella, and reducing Romboutsia; improves immune indices by elevating the spleen/thymus index, reducing inflammatory cell infiltration in the colon, and decreasing levels of pro-inflammatory cytokines IL-6 and TNF-α; it also strengthens the intestinal barrier and suppresses inflammation by increasing intestinal butyrate production. ⁴¹ In summary, P. heterophylla extracts exert broad anti-inflammatory effects across AD, COPD, and colitis by suppressing key cytokines and inflammatory pathways (e.g., NF-κB/MAPK, TLR4/MyD88, PI3K/Akt) while enhancing protective signals such as IL-10 and AMPK. They also improve tissue integrity and immune homeostasis, partly through gut barrier repair and microbiota modulation.

4.3. Hypoglycemic Activity

Extracts from P. heterophylla exhibit hypoglycemic effects. In type 2 diabetes mellitus (T2DM), impaired pancreatic β-cell function leads to insufficient insulin secretion. Recent studies have shown that cellular oxygen deficiency significantly contributes to the pathogenesis of diabetes. The polysaccharide H-1-2 from P. heterophylla ameliorates β-cell dysfunction by inhibiting hypoxic conditions, thereby reducing the inhibitory effect of the hypoxia-related factor HIF1α on Sirt1, a key protein in metabolic regulation. This upregulation of Sirt1 expression consequently improves abnormal blood glucose levels and metabolic disorders in T2DM. ⁴² Furthermore, Sirt1 serves as an upstream regulator of epithelial-mesenchymal transition (EMT). Polysaccharide H-1-2 inhibits EMT by activating Sirt1, which increases P-cadherin expression and decreases N-cadherin expression. This mechanism prevents hyperglycemia-induced podocyte death and ameliorates high glucose-induced podocyte dysfunction, suggesting a novel therapeutic target for diabetic nephropathy. ⁴³ Chen et al. demonstrated through in vitro experiments that polysaccharide H-1-2 from P. heterophylla significantly enhances glucose uptake and consumption in HepG2 hepatocellular carcinoma cells, 3T3-L1 adipocytes, and L6 myocytes without apparent toxicity. ¹⁹ Subsequent work by the researchers showed that polysaccharide 0.5MSC-F from P. heterophylla markedly increases insulin secretion from pancreatic β-cells (INS-1), which contributes to its hypoglycemic effects. ²¹ Additionally, combining P. heterophylla polysaccharide PF40 with metformin significantly ameliorates insulin resistance, with superior effects compared to monotherapy. ⁴⁴ Apart from polysaccharides, the cyclopeptides from P. heterophylla exhibit hypoglycemic properties. Notably, cyclopeptide Pseudostellarin E significantly accelerates the differentiation of 3T3-L1 preadipocytes into mature adipocytes and enhances insulin-stimulated glucose uptake under high-glucose conditions, suggesting a potential therapeutic agent for T2DM. ⁴⁵ Collectively, P. heterophylla extracts show hypoglycemic activity by restoring β-cell function via the hypoxia–HIF1α–Sirt1 axis and improving insulin secretion, glucose uptake, and insulin sensitivity. Polysaccharides may also protect against diabetic nephropathy by suppressing EMT, while cyclopeptides enhance insulin-stimulated glucose uptake. The partial mechanisms of P. heterophylla in immunoregulation, anti-inflammatory effects, and hypoglycemic effects are shown in Figure 6.

Figure 6.

Schematic diagram illustrating partial mechanisms of P. heterophylla in immune regulation, anti-inflammatory action, and hypoglycemic effects

4.4. Anticancer Activity

P. heterophylla, a traditional Chinese medicinal herb known for its tonic properties, may exert anti-tumor effects via immune modulation. In 1992, Wong isolated a polysaccharide fraction from P. heterophylla, designated as PH-I. Wong et al. reported that PH-I indirectly inhibits tumor growth by stimulating lymphocyte proliferation, enhancing immune cell activity, and inducing the production of Tumor Necrosis Factor. ⁴⁶ Subsequent purification of PH-I resulted in three subfractions: PH-I A, PH-I B, and PH-I C. Among these, PH-I C significantly enhanced the overall anti-tumor immune response. This enhancement is characterized by the activation of various immune cells, including macrophages, Natural Killer (NK) cells, and Cytotoxic T lymphocytes, as well as the induction of anti-tumor cytokines such as IFN-γ and IL-4 secretion. ⁴⁷ Further separation of PH-I C yielded PH-I Ca and PH-I Cb, among which PH-I Cb exhibited the strongest TNF-inducing capacity and anti-tumor activity. ⁴⁸ In summary, polysaccharides derived from P. heterophylla show promise as potential natural therapeutic agents for future cancer therapies.

Esophageal carcinoma is prevalent worldwide. Heterophyllin B inhibits the metastasis of this cancer by suppressing the PI3K/AKT/β-catenin signaling pathway. This suppression leads to the upregulation of E-cadherin and the downregulation of vimentin, Snail, MMP2, and MMP9. ⁴⁹ Pancreatic cancer, known for its refractory nature and often termed the “king of cancers,” is primarily driven by hypoxia. The polysaccharide H-1-2 from P. heterophylla counteracts this key driver. By antagonizing hypoxia and inhibiting the hypoxia-induced pro-tumor protein AGR2, H-1-2 effectively suppresses tumor growth, reduces metastasis, and prolongs survival in pancreatic cancer models. ⁵⁰ Overall, P. heterophylla shows anti-tumor potential via immune activation and direct pathway inhibition. Its polysaccharides enhance macrophage/NK/T-cell responses and cytokine release (e.g., TNF, IFN-γ), while heterophyllin B and H-1-2 suppress metastasis and hypoxia-driven growth by targeting PI3K/AKT/β-catenin and AGR2.

4.5. Cardioprotective Protective Activity

In traditional Chinese medicine, P. heterophylla is commonly used to treat palpitations, indicating potential cardioprotective properties. Contemporary research supports these traditional uses, identifying polysaccharides in P. heterophylla as likely pivotal bioactive components responsible for these effects. Tao et al. reported that crude polysaccharides from P. heterophylla significantly alleviated cardiopulmonary dysfunction and tissue damage in rats after acute myocardial infarction. This protective effect is likely associated with anti-inflammatory actions, inhibition of fibrosis, and enhancement of both systolic and diastolic cardiac function. ⁵¹ Using a CoCl₂-induced hypoxia model in H9c2 cells, Wang et al. demonstrated that saponin (PHS) and PHP fractions of P. heterophylla protected cardiomyocytes against hypoxic injury. The fractions notably decreased intracellular ROS generation, enhanced superoxide dismutase (SOD) activity, reduced malondialdehyde (MDA) levels, preserved cell membrane integrity, mitigated lactate dehydrogenase (LDH) leakage, and inhibited apoptosis. Collectively, these mechanisms significantly enhanced cardiomyocyte viability under hypoxic conditions. ⁵² Sun et al. found that polysaccharides from P. heterophylla attenuated myocardial ischemia-reperfusion injury. The underlying mechanism involves the downregulation of pro-apoptotic proteins Bax and Caspase-3, and the upregulation of the anti-apoptotic protein Bcl-2, thereby inhibiting cardiomyocyte apoptosis. ⁵³ In addition to polysaccharides, alkaloids in P. heterophylla also demonstrate cardioprotective properties. Specifically, three alkaloids isolated from P. heterophylla, named Pseudosterins A-C, have shown significant cardioprotective effects against sodium bisulfite-induced hypoxia-reoxygenation injury in H9c2 cardiomyocytes. Their efficacy surpassed that of the well-known active compound polydatin. ²³ Collectively, P. heterophylla exhibits cardioprotective potential, mainly attributed to polysaccharides and alkaloids. These components mitigate infarction and ischemia–reperfusion injury by reducing inflammation, fibrosis, oxidative stress, and apoptosis, improving cardiac function and cardiomyocyte viability under hypoxia.

4.6. Intestinal Protective Activity

Kong et al. reported that ethanol extract of P. heterophylla alleviates cellular oxidative damage by activating antioxidant enzymes such as SOD, CAT, GSH-Px, and reducing MDA levels. Concurrently, it modulates gut microbiota by increasing the abundance of beneficial genera such as Bifidobacterium and Lactobacillus, while reducing harmful bacteria. This dual action enhances systemic antioxidant capacity and improves gut health. ⁵⁴ Diabetes commonly induces intestinal mucosal damage and apoptosis of villous epithelial cells. The polysaccharide PF40 from P. heterophylla attenuates this damage. Its protective mechanism involves suppressing RORγ protein expression and increasing Foxp3 protein expression in the jejunum of rats with T2DM. Consequently, it restores the streptozotocin (STZ)-induced Th17/Treg cell imbalance, reduces the pro-inflammatory cytokine IL-17A, elevates the anti-inflammatory cytokine IL-10, and maintains intestinal immune homeostasis. These changes thereby ameliorate insulin resistance. ⁴⁴ In summary, P. heterophylla exhibits a convergent protective profile by simultaneously enhancing antioxidant defenses and rebalancing gut microbiota and mucosal immunity. Collectively, these coordinated effects restore intestinal homeostasis, suppress inflammation, and ultimately improve insulin resistance in diabetes. The partial mechanisms of P. heterophylla in anti-cancer, cardioprotective, and intestinal protective effects are shown in Figure 7.

Figure 7.

Schematic diagram illustrating the partial mechanisms of P.heterophylla in anticancer, cardioprotective, and intestinal protective effects

4.7. Nanoscale Application

Protein-polysaccharide conjugates derived from P. heterophylla self-assemble into pH-sensitive nanoparticles. When loaded with doxorubicin, these nanoparticles significantly enhance drug uptake efficiency and cytotoxicity in hepatocellular carcinoma cells, thereby improving their anticancer efficacy. ⁵⁵ Furthermore, the protein RPP from P. heterophylla forms nanocomplexes with curcumin, termed RPP-Cur. This complexation enhances the stability, cellular uptake efficiency, and antioxidant activity of curcumin. RPP-Cur enters cells via macropinocytosis and clathrin-mediated endocytosis, improving the delivery efficacy of this hydrophobic active ingredient. ⁵⁶ Collectively, P. heterophylla protein-based nanocarriers enhance stability, uptake, and anticancer/antioxidant efficacy of loaded bioactives.

4.8. Other Biological Activities

In addition to the previously mentioned applications, P. heterophylla exhibits significant biological activities. Organic extracts of P. heterophylla demonstrate potent activity in inhibiting lipid peroxidation, superior to that of Panax quinquefolius, and may serve as a cost-effective alternative in lipophilic antioxidant applications. ⁵⁷ Furthermore, saponin extracts from P. heterophylla protect the rabbit retina from laser-induced damage by enhancing antioxidant capacity, suppressing the expression of apoptosis-related genes, and reducing cell death. ⁵⁸ Tyrosinase, a key enzyme in melanin synthesis, plays a crucial role in skin whitening through its inhibition. Research confirms that methanol extracts, aqueous extracts, and the cyclic peptide HB from P. heterophylla inhibit tyrosinase activity. Notably, the aqueous extract exhibits slightly higher inhibitory activity, potentially due to its polysaccharide components like Angelica polysaccharides, known tyrosinase inhibitors. ⁵⁹ Additionally, HB demonstrates neuroprotective properties. In vitro studies reveal that HB counteracts β-Amyloid Protein-induced neuronal apoptosis, supports neuronal survival, and stimulates neurite regeneration. It also restores synaptophysin expression and reconstructs neural connections. In vivo, HB modulates the Th1/Th2 balance in the spleen, suppresses pro-inflammatory cytokines, and enhances anti-inflammatory cytokines in the brain. It alleviates neuroinflammation and improves cognition via the “spleen-brain axis.” This research establishes the first scientific basis for using P. heterophylla in brain health applications. ⁶⁰ Previously, a Kunitz-type trypsin inhibitor, which exhibited antifungal activity for the first time in this class, was isolated from the roots of P. heterophylla. ⁶¹ Subsequent studies showed that this inhibitor disrupts the cell membrane integrity of Colletotrichum gloeosporioides and Fusarium oxysporum, suppressing their growth and highlighting its potential applications in agriculture and the food industry. ⁶² Overall, P. heterophylla displays broad bioactivities, including lipophilic antioxidant, retinoprotective, and tyrosinase-inhibitory effects. Collectively, its cyclic peptide HB and trypsin inhibitor further provide neuroprotective and antifungal functions, highlighting promising applications in cosmetics, brain health, and agri-food fields.

4.9. Convergent Mechanisms

Pharmacologically, P. heterophylla exhibits pronounced pleiotropy: chemically distinct constituent classes (polysaccharides, cyclic peptides, and protein-derived peptides) repeatedly generate activities spanning immune regulation, metabolism, gastrointestinal protection, cardiovascular protection, and anticancer effects. Rather than reflecting unrelated actions, current evidence supports a convergence paradigm in which diverse components funnel into a limited set of upstream “triggering mechanisms” and shared signaling hubs, while final phenotypic outputs are determined by disease context, cell type, and immune–metabolic status.

A core triggering module is the TLR–NF-κB/MAPK inflammatory axis. Protein-derived peptides can directly engage pattern-recognition receptors: YG-9 binds TLR2/TLR4, drives IκB-α phosphorylation/degradation and p65 release, activates NF-κB, and elevates TNF-α, NO, and ROS, whereas RP-5 preferentially signals via TLR2.^29,30 Conversely, in inflammatory disease models, P. heterophylla extracts suppress NF-κB/MAPK activation and reduce pro-inflammatory cytokines. ³⁶ Consistently, a cyclic peptide extract ameliorates COPD by inhibiting TLR4/MyD88 and downstream MAPKs (p-JNK/p-p38/p-TAK1), decreasing TNF-α while increasing IL-10. ³⁷ In parallel, PI3K/Akt emerges as a convergent node linking inflammation, barrier integrity, and cancer-related programs. Heterophyllin B reduces NO, IL-6, IL-1β, and ROS production in LPS-stimulated macrophages via the PI3K/Akt pathway. ³⁹ In contrast, in esophageal carcinoma cells, HB suppresses PI3K/AKT/β-catenin signaling, thereby inhibiting EMT-related gene expression and metastatic potential, ⁴⁹ indicating a context-dependent modulation of PI3K/Akt signaling. Moreover, Heterophyllin B alleviates DSS-induced colitis by activating AMPK, repairing the intestinal mucosal barrier, and remodeling gut microbiota. ⁴⁰

Hypoxia-associated signaling involving HIF1α and Sirt1/SIRT1 provides a mechanistic bridge between metabolic disease and cancer-related phenotypes. In T2DM, H-1-2 alleviates hypoxia signaling in pancreatic β-cells and reverses the HIF1α upregulation/Sirt1 downregulation; mechanistically, HIF1α can directly bind the Sirt1 promoter and suppress its expression. ⁴² In diabetic nephropathy models, H-1-2 suppresses high glucose–induced EMT in podocytes, and SIRT1 is required for this protective effect. ⁴³ In pancreatic cancer, H-1-2 inhibits hypoxia-associated pathways and downregulates hypoxia-regulated AGR2, thereby suppressing tumor progression. ⁵⁰ Across systems, terminal outcomes converge on oxidative-stress attenuation and apoptosis restraint, as cardioprotective fractions/polysaccharides reduce ROS/MDA, enhance SOD, decrease Bax/Caspase-3, and increase Bcl-2.^52,53 Adaptive immune re-equilibration is likewise recurrent: PHP modulates Th1/Th2 responses via Ca²⁺/CaN/NFATc1-driven cytokine secretion, ²⁸ and PF40 restores Th17/Treg balance (RORγ/Foxp3; IL-17A/IL-10) in intestinal injury while improving insulin resistance. ⁴⁴ Future studies should explicitly validate “component–hub–phenotype” coupling through pathway-specific inhibition/knockdown, integrated multi-omics, and standardized in vivo PK–PD profiling to determine whether multi-activity is mediated by shared triggers (e.g., TLRs, hypoxia) and conserved hubs (NF-κB/MAPK, PI3K/Akt, AMPK, Sirt1).

Despite these diverse pharmacological activities, the realization of P. heterophylla’s medicinal and functional-food potential ultimately depends on a stable and high-quality raw-material supply. However, large-scale cultivation is increasingly constrained by continuous cropping obstacles, which reduce yield and quality and raise disease pressure. Therefore, beyond bioactivity, it is essential to clarify why replanting failure occurs and how it can be mitigated.

5. Continuous Cropping Obstacle in P. heterophylla

The continuous cropping obstacle in P. heterophylla refers to the decline in growth, yield, and quality, along with an increased incidence of pests and diseases, observed when P. heterophylla or related species are repeatedly cultivated in the same field. This issue poses a major constraint on the large-scale cultivation of P. heterophylla. The causes of this problem are multifaceted, involving soil conditions, microbial communities, and plant physiological responses. ⁶³

5.1. Causes of Continuous Cropping Obstacle

The formation of the continuous cropping obstacle stems from a complex interplay of factors involving the soil, biological elements, and the plants themselves. Recent studies highlight soil physicochemical degradation, microbial community imbalance, and plant autotoxicity as the primary causes of continuous cropping obstacles in medicinal plants.

As a medicinal plant, P. heterophylla selectively absorbs both mineral and trace elements, resulting in their persistent depletion in the soil and subsequent deficiency symptoms. ⁶⁴ Xia and Liu observed that total phosphorus and total nitrogen levels accumulated in fields continuously cropped with P. heterophylla over a period of 1-12 years. However, the levels of available potassium, nitrogen, and phosphorus diminished. Trace elements such as copper, zinc, and iron accumulated, whereas molybdenum levels declined after five years of continuous cropping. ⁶⁵ Prolonged cultivation of P. heterophylla frequently results in soil acidification. This is primarily due to phenolic and organic acids in root exudates, which release H⁺ ions and directly lower soil pH. Furthermore, these acids enhance H⁺-ATPase activity in the plasma membranes of pathogens like Fusarium spp., promoting H⁺ efflux into the soil. Simultaneously, these acids suppress the metabolic activity of beneficial microbes, including Trichoderma spp. and Pseudomonas spp., diminishing the release of alkaline substances such as ammonia and bicarbonate and thus reducing the soil’s pH buffering capacity. This results in a vicious cycle: acidic environment leads to pathogen proliferation, which further exacerbates soil acidification. This mechanism offers crucial insights into the rhizosphere microecology that underpins the obstacles associated with continuous cropping. ⁶⁶

Autotoxicity, a special form of allelopathy, occurs when plants secrete specific chemicals, known as autotoxins, through mechanisms such as root exudation, residue decomposition, or volatilization, which impede their own growth or that of closely related species. ⁶⁷ Research conducted by Wu et al. has demonstrated that the continuous monocropping of P. heterophylla results in a substantial buildup of autotoxins in the rhizosphere soil. The autotoxicity mechanism includes organic acids (such as tartaric and oxalic acids, with seven types identified) and phenolic acids (such as gallic and syringic acids, with nine types identified), which reshape the microbial community. Organic acids increase pathogen virulence directly by upregulating chemotaxis gene expression (such as cheA in Kosakonia sacchari), augmenting biofilm formation, and stimulating hydrogen peroxide (H₂O₂) secretion. Conversely, phenolic acids indirectly suppress beneficial bacteria and enhance pathogen reproduction by triggering toxin production (such as 3A-DON by Talaromyces helicus) and the formation of metabolic intermediates like protocatechuic acid. Together, these compounds inhibit the growth of beneficial bacteria, such as Bacillus spp., and suppress the expression of biocontrol genes, including srfAA and ituD. This imbalance in the fungi/bacteria ratio of the rhizosphere leads to reduced biomass, decreased quality, and the phenomenon of continuous cropping challenges in P. heterophylla.^68,69

Building on the evidence above, it is increasingly clear that continuous cropping obstacles in P. heterophylla are not driven by isolated factors, but by an interconnected and self-reinforcing rhizosphere deterioration process. Continuous monoculture leads to accumulation of phenolic acids and other allelochemicals in the rhizosphere, which in turn lower soil pH (acidify the soil) and suppress beneficial soil microbes. ⁷⁰ An acidic, toxin-rich soil environment selectively favors pathogenic microorganisms (e.g. Fusarium spp.) while inhibiting beneficial microbes. ⁷¹ This microbial dysbiosis further impairs the breakdown of autotoxic substances and exacerbates nutrient imbalances, creating a self-reinforcing cycle of soil degradation.^72,73 In P. heterophylla fields, such feedback loops have been confirmed by elevated phenolic acid levels coinciding with pH decline and proliferation of soil-borne pathogens under continuous cropping. ⁷⁴ Thus, soil acidification, microbial community shift, and autotoxic compound buildup are inherently interconnected mechanisms: each factor mutually amplifies the others, collectively contributing to replant growth obstacles and declining tuber yield in consecutive crops. By contrast, a neutral pH and rich beneficial microflora can degrade or detoxify allelochemicals, breaking this vicious cycle and promoting soil health. ⁷⁵ This vicious cycle and its key rhizosphere drivers are schematically illustrated in Figure 8.

Figure 8.

Schematic diagram of the vicious cycle mechanism underlying continuous cropping obstacles in P. heterophylla

5.2. Control Strategies for Overcoming Continuous Cropping Obstacles in P. heterophylla

Overcoming the continuous cropping obstacle in P. heterophylla necessitates a multi-dimensional approach that includes regulating soil microecology, optimizing cropping systems, and implementing biological interventions. Based on current research, the key control strategies are detailed below (Figure 9).

Figure 9.

Control strategies for overcoming continuous cropping obstacles in P. heterophylla

5.2.1. Fallowing and Soil Ecological Restoration

Fallowing interrupts the continuous cropping cycle, thereby facilitating natural soil recovery and altering the composition of the microbial community. Research indicates that fallowing notably decreases soil fungal diversity and increases bacterial abundance. This shift from a fungal-dominated to a bacterial-dominated community structure suppresses pathogen proliferation. ⁷⁶ For example, after one year of fallow, the population of the pathogenic fungus Fusarium oxysporum in the rhizosphere soil of P. heterophylla fields significantly decreased. ⁷⁷ Furthermore, soil organic matter content significantly increases during initial fallow periods but tends to decline with prolonged fallowing. Similarly, soil acidity gradually decreases as the fallow duration extends. ⁷⁶ In practical applications, adopting a rotation pattern of “P. heterophylla - fallow - P. heterophylla,” interspersed with 1-2 years of fallow and combined with straw incorporation, can significantly enhance soil carbon input and optimize microecology. ⁷⁸

5.2.2. Soil Sterilization

Soil sterilization uses physical or chemical methods to eradicate pathogens, effectively reducing the soil pathogen load. Physical soil sterilization, primarily through thermal treatment, can alleviate the continuous cropping obstacle for P. heterophylla by eliminating pathogens. For example, treating soil that has been continuously cropped for 15 years at 60°C for 12 hours, or at 120°C for 3 hours, resulted in a maximum yield increase of 545.16% for P. heterophylla. ⁷⁹ In field production, solarization in the high-temperature summer period, achieved by covering the soil with plastic film to increase soil temperatures to daily peaks of 45–55°C and maintaining these conditions for 7–14 days, effectively eradicates fungi such as Fusarium spp., offering a non-chemical method of disease control. ⁸⁰ Chemical sterilization involves using fumigants such as chloropicrin and sulfuryl fluoride. Although specific studies on P. heterophylla are scarce, research on similar medicinal plants, such as Panax notoginseng, indicates that chloropicrin fumigation significantly enhances soil nutrient status by increasing levels of nitrogen and phosphorus, and also affects soil enzyme activity. ⁸¹ It is critical to begin planting only after the complete dissipation of fumigant residues to preserve the quality of P. heterophylla.

5.2.3. Microbial Fertilizers and Biocontrol Agents

Microbial fertilizers that introduce beneficial microbial communities, such as Pseudomonas and Bacillus, to reconstruct the rhizosphere microecology, are currently a focal point of research. Functional microbial inoculants suppress pathogens via mechanisms that include competition for nutrients and the secretion of antibacterial substances. For instance, a study by Wu et al. demonstrated that four years of continuous application of a fertilizer containing Pseudomonas significantly diminished the presence of Fusarium oxysporum in the soil of continuously cropped P. heterophylla, enhanced polysaccharide levels, and nearly restored yields to those of non-continuously cropped systems. ⁸² Additionally, microbial fertilizers enhance the concentrations of soil enzymes, such as nitrous oxide reductase and nitrite reductase, which in turn improves soil nitrogen cycling. ⁸³

5.2.4. Optimization of Rotation and Intercropping Practices

Rational crop rotation curtails pathogen proliferation by modifying soil niches. The rice-P. heterophylla rotation serves as a representative model. During the rice growth phase, anaerobic conditions effectively inhibit aerobic pathogens such as Fusarium and simultaneously reduce the accumulation of harmful soil compounds, including acids, alcohols, and aldehyde ketones. ⁸⁴ Furthermore, the rotation of pepper with P. heterophylla reduces phenolic autotoxins in rhizosphere soil, optimizes microbial community structure, and alleviates soil acidification. This approach increases the abundance of beneficial microbes, including actinobacteria, nitrogen-fixing bacteria, and antagonistic fungi, and decreases pathogenic fungi, thus effectively overcoming the continuous cropping challenges associated with P. heterophylla. ⁸⁵ Intercropping systems strengthen systemic resistance by enhancing biodiversity. For example, intercropping P. heterophylla with Welsh onion (Allium fistulosum) not only increases the abundance of beneficial bacteria, including Pseudomonas and Nitrospira, but also reduces colonization space for pathogens. ⁸⁶ The research team headed by Wu Hongmiao demonstrated that mixed planting of P. heterophylla varieties not only enriches beneficial bacterial genera including Lactobacillus and Pseudomonas but also increases levels of key metabolites such as glycerol and D-fructose. This promotes a unique “rhizosphere dialogue” mechanism that inhibits soil-borne Fusarium wilt. ⁸⁷

In summary, research aimed at overcoming the continuous cropping challenges of P. heterophylla has evolved from single-technique approaches to multidimensional systemic regulation. Future research should integrate ecology, microbiome science, and molecular biology methodologies to enhance mechanistic understanding and refine application strategies. Priority research areas include leveraging metagenomics to map rhizosphere microbial interactions for precision microbial inoculants development, using synthetic microbial communities (SynComs) to construct stable rhizosphere microecosystems, and employing gene editing to curtail root-secreted autotoxin production, thus developing “allelopathic-inert” plant varieties. Additionally, balancing the ecological impacts of control measures is crucial to prevent excessive intervention that could degrade soil microecology, thus supporting the sustainable development of the P. heterophylla industry.

6. Conclusions

This review systematically summarizes recent advances in the chemical constituents, pharmacological activities, and continuous cropping obstacles of P. heterophylla. Current evidence indicates that cyclopeptides and polysaccharides represent major characteristic components, and that P. heterophylla exhibits broad pharmacological potential, including immunomodulatory, anti-inflammatory, hypoglycemic, anticancer, and cardio-/neuro-/gastrointestinal protective effects. Emerging directions—such as nanodelivery systems and neuroprotective applications—further expand its prospects for modern utilization.

Nevertheless, several key gaps remain. First, the fine structures, structure–activity relationships, in vivo biotransformation, and potential synergistic mechanisms of representative bioactive constituents require deeper clarification. Mechanistic evidence for therapeutic targets and signaling networks is still fragmented, and high-quality clinical and translational studies are limited. Second, sustainable industrial cultivation is severely constrained by continuous cropping obstacles arising from intertwined soil physicochemical degradation, rhizosphere microbial dysbiosis, and autotoxic compound accumulation. Although current practices (e.g., fallowing, soil sterilization, and microbial fertilizers) can partially alleviate replant failure, their long-term stability, ecological compatibility, and cost-effectiveness remain insufficient.

Accordingly, future research should prioritize: (i) multi-omics and advanced analytical strategies to resolve component structures and elucidate pharmacological mechanisms, especially those involving metabolic and neural regulatory networks; (ii) standardized pharmacokinetic–pharmacodynamic and safety evaluations to support robust clinical translation and product development; and (iii) rhizosphere-oriented cultivation innovation, including precision functional microbial agents, breeding of low-autotoxicity germplasm, optimization of eco-friendly rotation/intercropping systems, and establishment of intelligent and standardized quality-control frameworks. With continued integration of interdisciplinary research and industrial practice, the sustainable utilization of P. heterophylla resources and high-quality upgrading of the industry can be accelerated.