With continuous improvement of technology and ideas, it is becoming more intelligent, efficient, and environmentally friendly to obtain polysaccharides from plants. Selection of the appropriate technique is governed by the physicochemical properties of the target compounds, yield of polysaccharides, potential interfering substances, and overall process safety (Zhao et al., 2017). Comprehensively compare these parameters in different methods to determine the appropriate extraction method. Researchers also need to consider the impact on the environment, and efficient, green, economical, and environmentally friendly extraction methods are the most suitable.

There are several things that should be determined before the polysaccharide’s extraction process begins. These include the processing methods of the raw materials, the extraction methods and conditions, the selection of solvents, as well as the final purification methods for the polysaccharides. D. nobile polysaccharides are mainly located within the cell walls. To facilitate their release, mechanical damage is usually inflicted on plant tissues. Additionally, lipophilic substances included in plants should be removed to minimize impurities to ease purification. The most used solvents are petroleum ether and ethyl acetate (Zhang et al., 2020). These procedures are the foundation for the subsequent process of extraction. The choice of extraction method plays a key role in determining the reliability and yield of subsequent experiments. Currently employed methods for isolating D. nobile polysaccharides include hot water extraction (HWE), ultrasound-assisted extraction (UAE), and subcritical water extraction (SWE) (Figure 2).

Crude polysaccharides usually contain impurities such as pigments, proteins and low-molecular-weight compounds, which require further purification (Xue et al., 2024). Traditional methods of decolorization are hydrogen peroxide (H₂O₂) oxidation, adsorption on macroporous resin, and adsorption on activated carbon. When it comes to D. nobile, the most common two methods are the oxidation decolorization of H₂O₂ and activated carbon adsorption. Protein removal is typically achieved using the Sevag method or trichloroacetic acid precipitation, both of which operate by denaturing or precipitating proteins to separate them from polysaccharides (Li et al., 2019; Wang K. et al., 2024). Li et al. (2020) purified DNP (D. nobile polysaccharide) by using Sevag reagent to remove proteins from crude polysaccharides and decolorizing with activated carbon (Li et al., 2020). Further purification processes like column chromatography, membrane filtration, and stepwise precipitation are normally used to achieve an even higher purity (Liu et al., 2023; Wang et al., 2017). Columns of DEAE-cellulose, Sephadex G-series or Sepharose CL-series resins are commonly used among the chromatographic methods (Table 1). These processes yield highly purified D. nobile polysaccharide fractions suitable for omprehensive structural elucidation and bioactivity assessment.

Mw as a physicochemical parameter has a determinant effect on the solubility, viscosity, and bioavailability of the polysaccharides (Wang et al., 2023). Gas-liquid permeation chromatography (GPC) and high-performance gel permeation chromatography (HPGPC) techniques are the two most frequently used to measure Mw with D. nobile polysaccharides (Li et al., 2024a; Zhang et al., 2020). In GPC, different elution times are attributed to polysaccharides with different Mw. A compound with known Mw is used as a reference standard to draw the calibration curve, and then the Mw of the unknown sample is determined by referring to the elution time. The current procedure has become the analytical method adopted in daily analyses. HPGPC is a combination of GPC with high-performance liquid chromatography (HPLC); shorter analysis time, better repeatability and ability to measure purity are achieved. Reported D. nobile polysaccharides Mw values are distributed within a broad range of 3.01–500 kDa, which can be explained by the sources of plants, method of extraction and purification, processing conditions (Li et al., 2020; Wang et al., 2017). Such Mw range is commonly construed to be the determinant behind such pronounced differences in pharmacological activity. Thus, Mw continues to be an essential parameter during both basic and applied research of polysaccharide.

Polysaccharides are polymers of monosaccharides with the exact composition significantly affecting functional properties. Examples of common monosaccharides are glucose (Glc), galactose (Gal), arabinose (Ara), and fucose (Fuc). The composition is usually identified by 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatization technique or by acetylation-based technique (Liu et al., 2021). The polysaccharides of D. nobile are structurally diverse and often contain Ara, Gal, Glc, Man, Xyl, Rha and GalA (Hu et al., 2024; Li et al., 2022) (Table 2). The most commonly found monosaccharide are Gal, Glc and Man. In spite of the fact that certain polysaccharides contain identical monosaccharide, variation in molar proportion endows them with distinct structural and functional properties. As an example, both DNP and DNLP contain Man, Glc, and Gal, but the molar ratios of these components, 12.49%:65.2%:6.4% and 26.9%:66.2%:6.9%, indicate the differences in composition that can be the basis of the variations in bioactivity (Hu et al., 2024; Zhang et al., 2020).

Numerous studies have elucidated the chemical structure of polysaccharides derived from D. nobile. A novel polysaccharide, DNP1, was isolated, with its core structure consisting of →4)-β-Manp-(→1 and →4)-β-Glcp-(→1 sugar residues forming the backbone. Nuclear magnetic resonance (NMR) spectroscopy revealed that the repeating units of DNP1 likely consist of [→4)-2-OAc-β-Manp-(1→]3→4)-β-Glcp-(1→) (Li et al., 2024b). Luo et al. (2009) isolated a heteropolysaccharide, DNP, from the dry stems of D. nobile. Structural analysis through gas chromatography-mass spectrometry (GC-MS), infrared spectroscopy (IR), and NMR confirmed that DNP comprises (1→6)-linked-α-d-glucopyranosyl and (1→6)-linked-α-d-galactopyranosyl units, along with (1→4)-linked-α-d-glucopyranosyl and (1→4)-linked-α-d-mannopyranosyl branches (Luo et al., 2009). The proposed structure of DNP is depicted in Figure 3. Additionally, a study suggests that the polysaccharide extracted from D. nobile is mannoglucan. Jin et al. (2017) characterized polysaccharide JCS1 using chemical and spectral methods. The structure of JCS1 is primarily composed of α- and β-glycosidic linkages, with 1,4-linked Man and Glc as the main chains. Branching structures, formed through specific linkages, are present along the chains. The backbone of JCS1 is hypothesized to consist of alternating 1,4-glycosidic bonds between β-Manp and α-Glcp units, with branching at the C-6 position of the 1,4-linked α-Glcp residues, where 1,4-linked α-Xylp units replace α-Glcp. A T-α-Araf is attached at the C-4 position of the 1,4-linked α-Xylp, and additional branches may be formed via T-α-Glcp linkages at C-6 of the 1,4-linked α-Glcp. These findings support the classification of JCS1 as a mannoglucan (Jin et al., 2017). Research of D. nobile polysaccharides is primarily focused on the linkage, branching, and methylation structure of the monosaccharide units. Chemical composition of the polysaccharides has been presented in Table 2. Simple structure of polysaccharides is made up of monosaccharides linked to each other by glycosidic linkages, differing in the proportion of each monosaccharide. Such structural diversity makes analysis of the chemical composition of D. nobile polysaccharides very inconvenient.

Polycystic ovary syndrome (PCOS) is the most common endocrine illness that affects women of reproductive age, and most often it is caused by abnormalities of ovarian follicles, particularly of the follicular membrane (Helvaci and Yildiz, 2025). Symptoms that characterize the condition include excessive hair growth, acne, and obesity (Mousa et al., 2024). In order to test the therapeutic value of D. nobile polysaccharides (DNLP) against PCOS, researchers performed animal studies. PCOS was induced by the daily intraperitoneal treatment of the rats with letrozole (1 mg/kg) in a solution of carboxymethyl cellulose (0.5%) and feeding them a high-fat diet (30 days). Therapeutic effect of the oral DNLP administration (200 mg/kg/day) was then evaluated for 21 days according to quantitative analysis of ovarian morphology, serum glucose, insulin, hormone levels, expression of proliferating cell nuclear antigen (PCNA), Bax, Bcl-2, caspase-3 mRNA in ovarian tissue, and ovarian granulosa cell apoptosis. As compared with the model group, DNLP treatment led to a statistically significant decrease in body weight (P < 0.01) and normalized the estrous cycle. Even though there was a reduction in serum testosterone levels and indicators of insulin resistance, there was no change in the level of luteinizing hormone. A histological examination showed a significant decrease in follicles and corpus luteum, an increase in antral follicles, a disorganized arrangement of granulosa cells, and a thinning of the granulosa cell layer in the model group. After DNLP treatment the volume of corpus luteum was enhanced, the amount of antral follicles was reduced, and the layer of granulosa cells thickened when compared with the model group. The overall result of these studies suggests that DNLP has positive therapeutic in the treatment of PCOS.

Insulin resistance is common in PCOS. D. nobile polysaccharides (DNP) can regulate IR in granulosa cells of PCOS. In the situation when DNP (200 mg/kg/day per day for 30 days) was administered to PCOS rats, the body weight and ovarian weight were reduced, normal estrous cycle was restored, and hormonal levels and ovarian morphology were returned to normal. Moreover, DNP significantly decreased the level of serum glucose, insulin, HOMA-IR, and restored the expression of IGF1 and IGF1R in PCOS rats. These results were substantiated histologically by immunohistochemistry (IHC). Comprehensively, these results suggest that DNP intervention has the potential to rectify IR in rats with PCOS. Also, DNP intervention can also promote granulosa cells (GCs) glycolysis and improve the mechanism of follicular dysplasia. The effect of DNP on insulin sensitivity and glycolysis process of KGN cells treated with insulin further confirms this result. Interestingly, SIRT2 might be the key for DNP to regulate the glycolysis rate of granulosa cells (Hu et al., 2024; Liang et al., 2023; Martin and Madassery, 2006) (Figure 6).

Drinking alcohol is a prevalent social activity, but it can also cause many diseases (Patel et al., 2022). Alcohol-mediated injury is particularly prone to occur in gastrointestinal tract. Alcohol passes out rapidly along the esophagus, into the stomach and the small intestine and finally into the bloodstream through capillaries. This conduct has a direct impact on the epithelial cells of the gastric mucosal, breaking the protective mucosal barrier and causing acute gastric congestion, erosion, and, in some cases, superficial ulceration (Sun et al., 2025). Zhang et al. (2018) assessed the therapeutic effect and mechanism of the D. nobile polysaccharides (JCP) on ethanol-induced gastric injury in rats. The forty male Wistar rats were provided randomly into five groups: the control group, vehicle group, omeprazole group, low-dose (L-JCP, 100 mg/kg) and high-dose (H-JCP, 300 mg/kg) JCP groups. After 28 days of continuous gavage administration, all groups except the control group were induced with gastric ulcers through gavage with 100% ethanol (4 mL/kg). Gastric ulcer evaluation followed by histological analysis revealed that the ulcer indices for omeprazole, L-JCP, and H-JCP pretreated rats were 0.17% ± 0.16%, 0.78% ± 0.26%, and 0.32% ± 0.19%, respectively (P < 0.05). Compared to the vehicle group, JCP pretreatment reduced gastric hemorrhage and the occurrence of inflammatory cells. Intragastric administration of ethanol decreased the expression of SOD and increased MDA content in normal rats, whereas the H-JCP group showed a significantly higher SOD expression and low MDA accumulation. EGF, one of the major cell-protective growth factors that promote mucosal blood flow and epithelial cell proliferation, was considerably upregulated in the rats that were given 300 mg/kg JCP. Western blot analysis indicated that H-JCP group inhibited the expression of p-JNK, p-ERK, MMP-2 and MMP-9 in gastric tissue (Zhang et al., 2018; Zhang et al., 2020).

Vascular dementia (VD) is a cerebrovascular disease characterized by cognitive impairment and is an also common form of dementia. Its incidence rate has continued to rise in recent years. Its pathophysiology involves a series of events triggered by blood-brain barrier (BBB) disruption, endothelial dysfunction, and microcirculation failure, leading to neuronal energy depletion and excitotoxicity (Wang Y. et al., 2025). However, currently there are limited treatment options for this disease, which is a major challenge for the medical community (Zhong et al., 2024). Ferroptosis, a form of cell death driven by iron, is characterized by iron overload and excessive lipid peroxidation. Iron deposition and lipid peroxidation are key pathological features in neurodegenerative diseases (Ali et al., 2025). The explanation of ferroptosis has created new prospects in the study of the pathophysiology and therapeutic potential of VD (Ji et al., 2022). D. nobile polysaccharides (DNP) have the capacity to mitigate ferroptosis and maintain cognitive ability in VD rats. The current research involved 72 males of SD rats that were randomly divided into a sham operation group, a VD group, and a DNP group (100 mg/kg/day). The model and DNP groups were subjected to permanent ligation of the bilateral common carotid arteries, and an equal procedure was done on the sham operation group without the carotid artery ligation. The Morris water maze (MWM) test was used to examine the escape latency and the number of platform crossings. The tissue of the hippocampus was dissected after the end of the MWM experiment to determine GSH, GPx4, xCT, and PSD-95 expression and and mitochondrial morphology and ultrastructure were observed using transmission electron microscopy (TEM). The DNP group had significantly shorter escape latency (P < 0.05) and increased performance of platform crossing (P < 0.05) compared with the model group. The TEM analysis demonstrated that there are increased structures of the mitochondrial membranes and cristae in the DNP group. The GSH, xCT, and GPx4 levels in the hippocampus were increased in this group (P < 0.01). Besides, there was an increase of the synaptic vesicles, synaptic active zone (SAZ) length, thicker postsynaptic densities (PSD) and PSD-95 protein expression in DNP-treated rats. These results suggest that DNP can improve cognitive function in VD by alleviating ferroptosis (Hossain, 2009; Ming et al., 2023).

It is worth mentioning that DNP can also improve behavioral disorders caused by spinal cord injury (SCI) by inhibiting ferroptosis. The Basso-Beattie-Bresnahan scores of motor function in the DNP group were lower than those in the sham operation group (P < 0.05) and higher than those in the model group (P < 0.05) after 7, 14, 21, and 28 days of treatment. TEM observed that the mitochondrial membrane of the model group was damaged, and the mitochondrial cristae almost disappeared. However, after DNP treatment, there was improvement and a decrease in iron content (24 and 48 h after injury). The HE stains after 28 days of treatment showed that the spinal cord tissue defect area in the DNP group was smaller compared to the model group. And compared with the sham operation group, the xCT, GSH, Gpx4, and GRSFI in the spinal cord tissue of the model group rats decreased (P < 0.05), while the expression of these indicators increased after DNP treatment. NeuN⁺ is a commonly used marker for mature neurons. DNP treatment increased NeuN⁺ cells at 14 and 28 days after SCI (Huang J. et al., 2024; Wei et al., 2024). DNP has neuroprotective effects and can improve some neurological diseases by alleviating or inhibiting ferroptosis.

Inflammation is an automatic defense response of the body. It is closely related to the occurrence and development of many diseases, including arthritis, inflammatory bowel disease, diabetes, nervous system diseases, etc (Han et al., 2024; Lee et al., 2024). Therefore, studying the anti-inflammatory effects of polysaccharides from D. nobile can provide reference and inspiration for the treatment of these diseases. The important regulatory cells in the inflammatory process are macrophages. Chen et al. (2022) investigated the anti-inflammatory effects of D. nobile polysaccharides (DNP1 and DNP2) using lipopolysaccharide (LPS) - induced RAW264.7 macrophages as a model. Firstly, treatment of RAW264.7 macrophages with DNP1 and DNP2 at concentrations of 12.5, 25, 50, 100, and 200 μg/mL showed no cytotoxicity and significant cell proliferation. LPS stimulation can excessively increase the levels of inflammatory factors such as NO, TNF-α, IL-1β, IL-6 in RAW264.7 macrophages, inducing inflammatory responses, while DNP1 and DNP2 significantly reduce the production of inflammatory factors in a dose-dependent manner (Chen et al., 2022; Pan et al., 2014). The study is used to provide a theoretical basis of producing and using new products containing DNP1 and DNP2 with the aim of relieving inflammation. The team then investigated the mechanism through which DNP1 exerts anti-inflammatory effects, using surface plasmon resonance (SPR) binding assay, molecular docking techniques, and macrophage receptor blockade experiments. From the binding kinetic parameters and sensor graph of SPR, the dissociation constant value of DNP1 is 0. Molecular-docking technology has revealed that the binding energy of the DNP1 and TLR4-MD2 is −7.9 kcal/mol. The results of macrophage receptor blockade experiments showed that after treatment with different concentrations of DNP1, there were no significant changes in the release of NO, TNF-α, IL-1β, IL-6 from RAW 264.7. It is speculated that DNP1 may exert immunomodulatory effects by binding to the TLR4-MD2 complex and inhibiting the TLR4-MD2 mediated signaling pathway (Li et al., 2024; Zhang et al., 2023).

Plant viruses parasitize in plants and can affect their normal growth and development (Yuan et al., 2022). For crops, it also causes a decrease in their quality and yield. To explore more antiviral agents, researchers measured the anti-cucumber mosaic virus (CMV) and anti-tobacco mosaic virus (TMV) effects of 125 μg/mL⁻¹ DNPE6 (4) in tobacco using chitosan oligosaccharides (COS) and lentinan as controls. The protective activities of DNPE6 (4) against CMV and TMV were 40.4% and 69.9%, respectively. Among them, DNPE6 (4) has better protective activity against TMV than COS (39.1%) and lentinan (52.3%). After treatment with DNPE6 (4), NADPH oxidase and NAD(P)H increased. In addition, DNPE6 (4) can enhance the activity of defensive enzymes (POD, PAL, SOD) in tobacco. The PALS enzyme activity of the CK + DNPE6 (4) group reached its peak on the first day, while SOD and POD enzyme activities reached their peak on the third day. Moreover, the enzyme activities that reached their peak in the CK + DNPE6 (4) group were higher than those of the CK group. The enzyme activities of PALS and POD in the TMV + DNPE6 (4) treatment group peaked on third day, while that of SOD enzyme peaked on fifth day. A similar tendency was noted in the current study: the activity of enzymes was the highest in the TMV + DNPE6 (4) group and were higher than those in the TMV group. The above implies that DNPE6 (4) can effectively induce the host to produce defensive enzymes to resist plant virus infection. The effect of DNPE6 (4) on the expression of defense related genes was detected by RT-PCR. The results showed that DNPE6 (4) could increase the expression level of SOD and the expression levels of ICSI, EDSI, and PRI up-stream and down-stream of the Salicylic acid (SA) pathway, while inhibiting the protein expression of CAT. This information shows that DNPE6 (4) can accumulate SA and induce systemic acquired resistance (SAR). In summary, DNPE6 (4) exhibits anti-CMV and anti-TMV effect (Li et al., 2019). Subsequently, the antiviral effect of DNPE6 (11) against CMV, TMV, and potato virus Y (PVY) were studied. DNPE6 (11) has significant therapeutic and inactivation activity against CMV, significant protective effect against PVY, and greater efficacy than that of the control Ningnanmycin. In addition, preliminary mechanistic studies have found that DNPE6 (11) has superior binding ability with cucumber mosaic virus coat protein (Li et al., 2020; Mohan et al., 2020). Taken together, DNPE6 (4) and DNPE6 (11) can be deemed as potential antiviral compounds.