The water extraction method has the advantages of operability, pollution-free, simple method, low cost, etc. It is widely used for the extraction of polysaccharides and is suitable for industrial application. But at the same time, it requires high extraction temperature, takes a long time, has low efficiency, low safety, and is difficult to purify, while repeated continuous extraction is very easy to damage the chemical structure of polysaccharides and affect the stability of polysaccharides (Yuan, 2015).

Jiang et al. used Box Behnken design to optimize the extraction process of polysaccharides from Salvia miltiorrhiza residue. The results showed that the extraction time, extraction temperature and water to material ratio were the important factors affecting the extraction rate of polysaccharides. The optimized extraction condition was as follows: the extraction time was 2.6 h, the extraction temperature was 89°C, the volume ratio of water to raw material was 32:1, and the extraction rate of crude polysaccharide was around 27.32% (Jiang et al., 2015). Cai’s research showed that the optimal extraction process of Salvia miltiorrhiza polysaccharide is soaking in water for 2 h, heating to boiling for 30 min, filtering, then decocting for 25 min and filtering, collecting the filtrate twice, the concentrated solution contains 2 g/mL of Salvia miltiorrhiza, adding anhydrous ethanol to make its concentration up to 80%, placed at a constant temperature of 20°C for 4 h, and centrifuged to precipitate to obtain Salvia miltiorrhiza polysaccharide (Cai et al., 2010).

Ultrasound technology can induce deformation and rupture of tissues and facilitating the release of intracellular contents, thus promoting the dissolution of active components in cells. This process is characterized by its rapidity, precision, and stability, which is conducive to the dissolution of effective components. The method requires no heating and has a high extraction rate. But high power will destroy the polysaccharide structure, extracellular substances cause separation difficulties (Huang, 2010).

Jiang et al. optimized the extraction process of polysaccharides from Salvia miltiorrhiza using response surface methodology. The optimized extraction process was the extraction temperature of 54°C, the ultrasonic power of 180 W, the extraction time of 32 min, and the extraction rate of up to 40.54% (Jiang et al., 2014). Zhao optimized the ultrasonic extraction process of Salvia miltiorrhiza polysaccharide through orthogonal test. Among them, the ratio of material to liquid has the greatest impact on the extraction rate of Salvia miltiorrhiza polysaccharide. The optimal extraction process conditions was: the ratio of material to liquid (m/V) was 1∶12, the extraction temperature was 50°C, the extraction time was 40 min, and the extraction times were 3. Under this condition, the extraction rate of Salvia miltiorrhiza polysaccharide was 5.43% (Zhao, 2014).

Enzymatic extraction has the advantages of convenience, specificity, easy removal of impurities, high efficiency, cost saving and energy consumption reduction. Based on this, enzymatic extraction has broad application space. But the cost of enzyme extraction is very high (Zhang et al., 2010). Depending on the specificity of the enzyme, the complex enzyme is used in the experiment to coordinate the relationship between substrate, inhibitor and enzyme concentration, according to its required pH, temperature and time.

Cai et al. optimized the extraction process of Salvia miltiorrhiza polysaccharide by cellulase method. The results showed that the optimal extraction process of Salvia miltiorrhiza polysaccharide by cellulase method was temperature 60°C, enzyme amount 5%, and extraction time 120 min. Under this condition, the extraction rate of polysaccharide was 108.9 g/kg (Cai et al., 2008). Yang et al. optimized the extraction process of polysaccharides from Salvia miltiorrhiza by cellulase using response surface methodology. On the basis of single factor investigation and response surface methodology, they finally concluded that the optimal enzyme extraction process was 0.5% enzyme addition, 65°C enzymatic hydrolysis temperature, 120 min extraction time, and the extraction rate of polysaccharide was 2.59 mg/g (Yang and Zhang, 2016).

Microwave energy penetrates the cell wall and reaches the cell interior in the presence of a solvent. The elevated temperature and pressure facilitate the absorption of microwave energy by both the solvent and the intracellular components. When the internal pressure exceeds the structural integrity of the cell, the cell wall ruptures and the cell material flows out and dissolves in the solvent. So as to improve the extraction rate. Microwave extraction has the advantages of simplifying operation steps, saving solvent, safety and pollution-free, and improving extraction rate. However, the disadvantage of this method is consumption, and the polysaccharide structure is easy to be destroyed (Jun-Mei et al., 2010).

According to Meng et al., the microwave-assisted extraction process of crude polysaccharides from Salvia miltiorrhiza (SMPs) was optimized by investigating four independent variables, microwave power, extraction time, solvent solid ratio and ethanol concentration. The results showed that the optimum extraction conditions were: microwave power 1200W, extraction time 12 min, solvent to solid ratio 38%, ethanol concentration 86%, and the final extraction rate of crude polysaccharide 14.11% (Meng et al., 2022). Zhao also optimized the extraction of polysaccharides from Salvia miltiorrhiza by microwave through single factor experiment and orthogonal design. By taking the extraction yield of polysaccharides as the evaluation index, the material-to-liquid ratio, extraction temperature, extraction time, and number of extractions were optimized. The optimum extraction conditions were as follows: 1: 12 g/mL, 50°C, 40 min, achieving a polysaccharide extraction yield of 5.43% (Zhao, 2014) (Table 1).

Because the polysaccharide has no conjugated system and no ultraviolet absorption, the polysaccharide is usually hydrolyzed into monosaccharides before being determined by instrumental analysis technology when analyzing the monosaccharides composition of Salvia miltiorrhiza polysaccharide. High performance liquid chromatography (HPLC) (Wang et al., 2016), high-performance liquid chromatography-mass spectrometry (HPLC-MS) (Zhao et al., 2019), high-performance anion exchange chromatography (HPAEC-PAD) (Giannelli et al., 2020), high performance capillary electrophoresis HPCE (Ma et al., 2017), gas chromatography-mass spectrometry (GC-MS) (Grace et al., 2013) and other chromatographic methods are commonly used to determine monosaccharide composition. Meng et al. utilized microwave-assisted extraction followed by continuous purification using DEAE Sepharose Fast Flow and Sephadex G-100 chromatography to obtain SMP1 from Salvia miltiorrhiza polysaccharides, which comprised glucose, galactose, and fructose in a molar ratio of 1:1.67:1.12 (Meng et al., 2022). Wang et al. extracted the crude polysaccharide from Salvia miltiorrhiza by water extraction and ethanol precipitation, and separated and purified the polysaccharide components by DEAE-52 cellulose column and Sephadex G-100 gel filtration column. After hydrolysis by trifluoroacetic acid and derivatization of 1-phenyl-3-methyl-5-pyrazolone (PMP), The monosaccharide composition of the polysaccharide and its molar ratio were determined by HPLC method: glucose: arabinose: xylose: mannose: galacturonic acid = 1.42: 2.14: 1.16: 2.10: 1 (Wang et al., 2014). This indicates that Salvia miltiorrhiza polysaccharides primarily consist of monosaccharides such as glucose, arabinose, rhamnose, and galactose, with varying compositions and molar ratios depending on the extraction, separation, purification, and analytical methods employed.

The glycosidic linkage of polysaccharides can affect its form in solution, which is one of the important factors affecting its biological activity and one of the important indicators to characterize the biological activity of polysaccharides. At present, the research on the structure of Salvia miltiorrhiza polysaccharide mainly focuses on its primary structure. The connection methods for determining glycosidic bonds can be divided into chemical analysis method and instrumental analysis method. Chemical analysis methods include periodate oxidation method (Zhang et al., 2021), Smith degradation method (Perepelov et al., 2018), methylation method (Li et al., 2016), etc. Methylation involves methylating the glycoside chain, followed by GC-MS analysis after hydrolysis. Instrumental analysis methods include nuclear magnetic resonance (NMR) (Uhliarikova et al., 2021), GC-MS (He et al., 2017), Fourier transform infrared spectroscopy (FT-IR) (Chen et al., 2019a), etc. Zhao et al. extracted Salvia miltiorrhiza polysaccharide from 8% sodium hydroxide solution (H-8) and characterized it by GPC, FT-IR and NMR spectra. The results showed that the main chain was 4- β- D-Xylp, branch is 3- α- L-Arafat or 5- α- L-Araf-1, 4- β- D-Galp and β- D - Glcp, and α- L-Rhap, α- D-Galpa and α- Connected by D-GlcpA fragments (Zhao et al., 2020). Jing et al. characterized the structure of the extracted PSMP-2 by HPGPC, HPLC, FT-IR and methylation analysis, and found that the extracted PSMP-2 contains five main glycosidic bonds, (1 → 2,4) - linked Rha, (1 → 6) - linked Gal, (1 →) - linked Ara, (1 → 3,6) - linked Gal, (1 → 4) - linked Gal (Jing et al., 2022). See Table 3 for details. The possible structural model of Salvia miltiorrhiza polysaccharide is shown in Figure 3.

The molecular weight of Salvia miltiorrhiza polysaccharides has been primarily determined using gel permeation chromatography (GPC) and high-performance gel permeation chromatography (HPGPC) (Jiang et al., 2016). Jiang et al. extracted Salvia miltiorrhiza polysaccharide by hot water extraction, and separated and purified Salvia miltiorrhiza polysaccharide with DEAE-Sepharose CL-6B column and Sephadex G-100 column, and obtained a new polysaccharide with antioxidant activity, namely, SMWP-1, which was obtained by GPC. The molecular weight determined by the method is 5.27 × 10⁵ Da (Jiang et al., 2015). Ji et al. extracted Salvia miltiorrhiza polysaccharide by ultrasonic extraction, and then purified the polysaccharide by water dialysis to obtain SMGP. The average molecular weight of SMGP detected by HPGPC was 1.55 × 10⁵ Da (Ji et al., 2022). The molecular weight, monosaccharide composition, molar ratio and sugar chain structure of Salvia miltiorrhiza polysaccharides were obtained by different extraction and purification processes, as shown in Table 2. Therefore, we cannot uniformly define the structural characteristics of Salvia miltiorrhiza polysaccharides.

Coronary artery occlusion and myocardial injury or death can result in myocardial infarction (MI) or even heart failure, with a high mortality. Myocardial regeneration potential is extremely limited. Myocardial cells undergoing necrosis or apoptosis during myocardial infarction (He and Chen, 2020). Reperfusion is considered as the first effective strategy to save ischemic myocardium, but is accompanied by a series of adverse effects (Singhanat et al., 2021). Therefore, the demand for potential natural products with lower toxicity and fewer side effects is increasing. Numerous studies have demonstrated that polysaccharides have protective effects on myocardial cells, such as Ganoderma lucidum (Kahveci et al., 2021), Chuanmingshen (He et al., 2022). Zhou et al. used 200 μmoL/L H₂O₂ to induce neonatal rat cardiomyocytes in vitro to establish a myocardial injury model, and gave Salvia miltiorrhiza polysaccharide intervention. It was found that Salvia miltiorrhiza polysaccharide in different dosage groups (Low dose group: 1 × 10⁻⁵ moL/L; Medium dose group: 5 × 10⁻⁵ moL/L; High dose group: 1 × 10⁻⁴ moL/L) could significantly increase the expression of prohibitin protein in myocardial cells, especially in the high-dose group, suggesting its potential Salvia miltiorrhiza polysaccharide could protect myocardial cells from H₂O₂ induced damage (Zhou et al., 2011). Geng et al. isolated SMP1 from the root of Salvia miltiorrhiza and induced H9c2 myocardial cell damage through H₂O₂. It was found that pretreatment with SMP1 (25, 50 and 100 μg/mL) significantly prevented the mitochondrial damage, cytochrome c release, the increase of the ratio between apoptosis promoting Bax and anti-apoptosis BCl-2 protein expression, and the activation of caspase-3 in H9c2 cells stimulated by H₂O₂. SMP1 protects H9c2 cells from H₂O₂ induced apoptosis by inhibiting mitochondrial dysfunction, inactivating caspase-3 cascade and enhancing antioxidant capacity to protect cardiomyocytes (Geng et al., 2015a). Song et al. studied the protective effect of water-soluble Salvia miltiorrhiza polysaccharide SMP1 on the heart of rats with ischemia reperfusion (I/R) model. The results showed that SMP1 (400 and 800 mg/kg) could prevent I/R induced myocardial infarction by improving oxidative stress and inhibiting cardiomyocyte apoptosis (Song et al., 2013). It can be seen that Salvia miltiorrhiza polysaccharide can protect myocardium, and its mechanism may be related to improving oxidative stress of myocardial cells, inhibiting apoptosis of myocardial cells and promoting autophagy (Figure 4).

Autoimmune attacks on hepatocytes, viral infections, drug abuse, and other factors can lead to liver injury (Malhi and Gores, 2008). Liver injury is influenced by multiple factors, and the underlying mechanisms of its pathogenesis and progression remain incompletely understood. A large number of studies have shown that polysaccharides can prevent and improve chemical liver injury and immune liver injury, such as Angelica sinensis (Cao et al., 2018), Schisandra chinensis (Yuan et al., 2018), etc. Song et al. established an immune liver injury model in mice through Bacille Calmette Guerin and lipopolysaccharide. The study found that Salvia miltiorrhiza polysaccharide (SMPS) (Low dose: 90 mg/kg; Medium dose: 180 mg/kg; High dose: 360 mg/kg) can effectively improve the thymus index, spleen index and liver index, reduced serum levels of nitric oxide (NO), aspartate aminotransferase (AST), and alanine aminotransferase (ALT), and restored tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in the liver and has protective effect on immune liver injury (Song et al., 2008). Han et al. established a liver cell injury model by carbon tetrachloride, and studied the effects of Salvia miltiorrhiza polysaccharides (SMPs) (Dosage: 0.5, 1, 2 g/L) on chicken liver cell injury in vitro and in vivo. The results showed that the contents of TP, Alb and GSH were significantly increased, while the levels of liver index, ALT, AST and MDA were significantly decreased, indicating that SMPs had good protective effects on chicken liver injury in vivo and in vitro (Han et al., 2019). Yao et al. studied the effects of different concentrations of Salvia miltiorrhiza polysaccharide solution (High dose group: 15.6 g/kg, medium dose group: 7.8 g/kg and low dose group:3.9 g/kg) on acute liver injury in mice. The prepared Salvia miltiorrhiza polysaccharide was given to the mouse model of acute liver injury induced by tail vein injection of lipopolysaccharide (LPS), and its protective effect on the liver was observed. The results showed that Salvia miltiorrhiza polysaccharide could reduce the content of MDA in liver tissue, increase the content of GSH, and reduce the content of ALT in serum of mice with acute liver injury induced by LPS (Yao et al., 2010). It can be seen that the protective mechanism of Salvia miltiorrhiza polysaccharide on the liver may be related to its inhibition of the activation of TLR4/MyD88 signal pathway, inhibition of excessive peroxidation in the liver, and reduction of the production of inflammatory factors (Figure 5).

The regulation of immune response plays a critical role in the prevention of diseases. Recent studies have highlighted that the immune regulation and immune stimulation induced by bioactive compounds are increasingly valued (Yu et al., 2016). Immunomodulators primarily consist of protein adjuvant (Cui et al., 2018), aluminum hydroxide (He et al., 2015), and Freund’s adjuvant (FA) (Behr and Divangahi, 2015). However, neither aluminum hydroxide nor FA can induce strong cellular immunity. Protein adjuvants are too expensive to be commercialized. Therefore, it is urgent to develop a new immune adjuvant with high efficiency, low toxicity and abundant resources (Fan et al., 2010). Plant polysaccharides have obvious advantages in improving humoral and cellular immunity, such as mulberry leaves (Chen et al., 2019b), atractylodes macrocephala (Sun et al., 2015), etc. Plant polysaccharides can regulate the immune system by stimulating immune cells, regulating the release of cytokines, promoting of antibody secretion, etc. It plays an obvious role in improving humoral immunity, cellular immunity and mucosal immunity, and hold promise as potential metabolites for developing immune modulators (Jiang et al., 2010). Salvia miltiorrhiza polysaccharides also have immunomodulatory effects. Chen et al. found that SMP can significantly promote the proliferation of lymphocytes, and can enhance the cytotoxicity of T lymphocytes to cancer cells. Increase the gene expression of cytokines (such as IL-4, IL-6 and IFN-γ), enhance the gene expression of TLR1, TLR2 and TLR4; increase the protein expression of p-JNK, p-ERK, IKKα and IKKβ; reduce the level of IκBα. This indicates that SMP has specific regulatory effect on T lymphocytes through MAPK and NF-κB signaling pathways (Chen et al., 2017). Wang et al. found that SMPA (200 mg/kg) could improve immune organ indexes in gastric cancer rats. SMPA significantly stimulates splenocyte proliferation, promotes the production of anti-inflammatory cytokines such as IL-2, IL-4 and IL-10, inhibits the secretion of pro-inflammatory cytokines such as IL-6 and TNF-α, and enhances NK cells and T lymphocytes cytotoxicity and increased phagocytosis of gastric cancer rat macrophages. In addition, SMPA significantly increased total intracellular granzyme-B and IFN-γ levels produced by splenocytes. SMPA may act as a potent immunomodulator and may be a potential complementary source for gastric cancer treatment (Wang et al., 2014). Zhang et al. found that Salvia miltiorrhiza polysaccharide (200 mg/kg) can significantly promote lymphocyte proliferation reaction in mice; enhance the phagocytosis of peritoneal macrophages in mice; Inhibits ear swelling and decreases vascular permeability caused by dinitrofluorobenzene-induced allergic contact dermatitis of the pinna in mice, and significantly inhibits the expression of iNOS, IFN-α and IL-1β mRNA and other genes, mainly affects the organ index of the immune organs thymus and spleen, and has the effect of protecting the body from damage caused by the overexpression of cytokines, demonstrating good immune regulatory activity (Zhang et al., 2012). It can be seen that Salvia miltiorrhiza polysaccharide has immunomodulatory activity, and its mechanism of action may be related to the promotion of T lymphocytes and macrophages (Figure 6).

Cancer is one of the diseases that seriously harm human health, and with poor clinical outcomes. Its cancer cells are easy to spread within the body, the pathogenesis is diverse, prolonged treatment process, difficulty in cure, and high mortality. The main mechanism of standard biomedical treatment in treating cancer is to use drug toxicity to kill cancer cells. At present, no current drug selectively targets cancer cells without affecting normal cells (Alas et al., 2021). Plant polysaccharides can activate the immune system and play an immune regulatory role, and they can inhibit the proliferation of tumor cells, but have almost no toxic and side effects on normal cells (Yu et al., 2018), such as Astragalus polysaccharide (Shi et al., 2024), Ginseng polysaccharide (Zheng et al., 2025). Liu et al. obtained Salvia miltiorrhiza polysaccharide SMP-W1 through extraction and purification. After incubating H22 cells with SMP-W1 of different mass concentrations for 48 h, the cell activity was detected by MTT colorimetry. The results showed that with the increase of SMP-W1 concentration to 400 μg/mL, the cell activity decreased significantly, suggesting that SMP-W1 showed an inhibitory effect on the proliferation of H22 cells; It was found in vitro that it increased the activities of rat serum superoxide dismutase (Takahashi et al., 2023), catalase (CAT), glutathione peroxidase (GSH-Px), as well as the secretion of TNF-α. It has good anti-tumor activity in vitro (Liu et al., 2013). Jiang et al. purified the extracted Salvia miltiorrhiza polysaccharide to obtain SMP-U1. The study found that SMP-U1 directly inhibited the proliferation of Bcap-37 and Eca-109 cells, had a good anti-tumor activity, and the activity was good at the concentration of 0.30 mg/mL (Jiang et al., 2014). Wang et al. investigated the anti-tumor effects of 200 μg/mL SMP on human colorectal cancer LoVo cells, and finding that SMP exhibited a high inhibition rate on LoVo cells in a dose- and time-dependent manner; The polysaccharide can induce apoptosis of LoVo cells, block cell cycle in S phase, and increase intracellular reactive oxygen pressure. It is speculated that Salvia miltiorrhiza polysaccharide may have the potential to develop into a natural anti-cancer drug (Wang et al., 2018a). It can be seen that Salvia miltiorrhiza polysaccharide can play an anti-tumor role by improving the immune capacity of the body, inhibiting the growth of tumor cells and anti-oxidation.

The human body produces free radicals in the body due to continuous contact with the outside world, and excessive free radicals will lead to aging, cancer or other diseases (Liu et al., 2018). Liu et al. conducted the first study on the antioxidant activity of Salvia miltiorrhiza bungeana polysaccharide (SMP) extracted via water extraction and ethanol precipitation, and studied the antioxidant activity of the polysaccharide of Salvia miltiorrhiza bungeana for the first time. The results indicated that SMP effectively inhibited linoleic acid peroxidation, and exhibited significant reducing power. Its both the inhibition rate and reducing power increased with higher mass concentrations, demonstrating a clear dose-response relationship. The inhibitory rate of 1 mg/mL Salvia miltiorrhiza polysaccharide on linoleic acid peroxidation was 23.05%. The results showed that the polysaccharide of Salvia miltiorrhiza Bunge had antioxidant activity and obvious inhibition on the peroxidation of linoleic acid (Zhen-Liang et al., 2013). Yong et al. extracted and purified Salvia miltiorrhiza polysaccharide by DEAE-52 cellulose column and Sephadex G-100 column chromatography to obtain an acidic polysaccharide PSMP-2, The study found that PSMP-2 demonstrated excellent scavenging capacity for DPPH and hydroxyl radicals, enhanced the activity of antioxidant enzymes in vivo, and has good antioxidant activity (Jing et al., 2022). Jiang et al. separated a new polysaccharide SMWP-1 with antioxidant activity from Salvia miltiorrhiza residue, which showed potent scavenging and reducing abilities against superoxide ions, DPPH, and hydroxyl radicals in vitro. SMP-1 has good effect at the concentration of 0.25 mg/mL (Jiang et al., 2015). Qi et al. optimized the extraction process of Salvia miltiorrhiza polysaccharide by response surface methodology, and then carried out antioxidant research. The results showed that it had obvious scavenging capacity for hydroxyl radicals, and the higher the concentration of polysaccharide, the stronger its scavenging capacity. The optimal effect was observed at a concentration of 4.5 mg/mL (Xiao-Ni et al., 2016). In conclusion, Salvia miltiorrhiza polysaccharide can play an antioxidant role by scavenging free radicals, improving antioxidant enzyme activity and other ways (Figure 7).

Salvia miltiorrhiza polysaccharide not only has the activities of immune regulation, anti-tumor, anti-oxidation, myocardial cell protection, liver protection, but also has the effects of nerve protection (Zhang and Wei, 2016), blood pressure reduction (Xiao-Hong et al., 2017), kidney protection (Wang et al., 2022), anti-inflammatory (Han et al., 2018), etc. Shen et al. found that in the process of freezing boar semen, 0.4 mg/mL Salvia miltiorrhiza polysaccharide (SMP) can play a role in protecting boar sperm from oxidative damage, and can enhance sperm vitality, improve pregnancy rate. It is speculated that it is expected to be used in human or endangered wild animal sperm conservation (Shen et al., 2015). Han et al. studied the anti-inflammatory effect of SMP on 264.7 cells induced by lipopolysaccharide. The results showed that SMP significantly inhibited the mRNA transcription of TNF-α, IL-6, iNOS and COX-2 and the protein expression of NF-κB, p-p65 and p-IκBa, indicating that SMP has anti-inflammatory effects (Han et al., 2018). (Table 4) Salvia polysaccharides can also be used in combination with other drugs. Han et al. found that the combination of FFC and SMPs could improve the growth performance of broilers, increase the number of leukocyte subtypes in blood (P < 0.05), increase the number of Newcastle disease (ND) and avian influenza (AI) antibodies, the number of immunoglobulins and the contents of cytokines in blood (P < 0.05). The lymphocyte conversion rate in peripheral blood of broilers was significantly increased (P < 0.05), and the immune response of broilers was enhanced (Han et al., 2021). Wang et al. found that the combination of salviorrhiza polysaccharides with bifidobacterium bifidum V (BbV) and Lactobacillus plantarum X (LpX) in human microbiota decreased the mRNA concentrations of pro-inflammatory factors (tumor necrosis factor α, interleukin1β [IL-1β] and IL-6) (Wang et al., 2020).