A Review of the Mechanisms of Astragaloside IV and Berberine in Vascular Dysfunction Associated with Obesity and Diabetes

Introduction

The global prevalence of obesity and diabetes has reached epidemic levels, posing significant public health challenges and placing substantial strain on healthcare systems. According to The Lancet, nearly 880 million adults were classified as obese in 2022, marking a 4.5-fold increase since 1990.¹ Meanwhile, the International Diabetes Federation reported that approximately 537 million adults were living with diabetes in 2021, with this number expected to rise sharply in the coming years.² Both obesity and diabetes contribute to a range of severe health complications, including cardiovascular diseases, diabetic retinopathy, nephropathy, encephalopathy, and neuropathy, leading to significant increases in morbidity and mortality.

Vascular dysfunction, a key underlying factor in the pathogenesis of these complications, is common and often an early feature in both obesity and diabetes.^3–5 Characterized by impaired endothelial function, abnormal vascular remodeling, and chronic inflammation, vascular dysfunction disrupts the homeostatic balance between vasodilation and vasoconstriction, coagulation, and fibrinolysis, as well as pro-inflammatory and anti-inflammatory responses.^6,7 In obesity, excessive adipose tissue promotes vascular dysfunction through the release of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6).⁸ These cytokines drive oxidative stress and endothelial damage while reducing the bioavailability of nitric oxide (NO), essential for vascular relaxation and homeostasis.^9,10 Insulin resistance, a hallmark of obesity, exacerbates endothelial dysfunction by impairing insulin-mediated NO production and promoting vasoconstriction.¹¹ Clinical evidence from a cross-sectional study (N = 8,823) reveals significant associations between abdominal obesity (quantified by the A Body Shape Index) and endothelial dysfunction, evidenced by inverse correlations with flow-mediated vasodilation (men: r = −0.23, P = 0.003; women: r = −0.32, P < 0.001).¹² Similarly, diabetes accelerates vascular damage via hyperglycemia-induced mechanisms, such as advanced glycation end-product (AGE) formation, increased oxidative stress, and the activation of inflammatory pathways.^13–15 Hyperglycemia also triggers endothelial cell apoptosis and impairs vascular repair processes, leading to progressive damage in both macrovascular and microvascular systems.^16,17 A population-level analysis (N = 1,384) highlights the vascular effects specific to diabetes, with diagnosed patients exhibiting a 42% prevalence of endothelial dysfunction and significantly lower reactive hyperemia index (RHI) values compared to 23% in normoglycemic controls.¹⁸ The interplay between obesity and diabetes exacerbates vascular dysfunction. For instance, obesity-induced insulin resistance amplifies the harmful effects of hyperglycemia on endothelial cells, while diabetes-related vascular damage worsens the pro-inflammatory state triggered by obesity. This vicious cycle underscores the critical importance of targeting vascular dysfunction in the management of obesity and diabetes.

Current pharmacological therapies, including GLP-1 agonists, SGLT2 inhibitors, and metformin, have demonstrated clinical benefits in managing obesity- and diabetes-associated vascular complications through mechanisms such as glycemic control, anti-inflammatory actions, and oxidative stress reduction. However, challenges such as hypoglycemia risk (particularly with intensive insulin therapy), gastrointestinal side effects and variable cost-effectiveness in long-term use remain unresolved.^19–21 These limitations emphasize the urgent need for safer, cost-effective, and multi-target alternatives to address these complex vascular complications. Natural bioactive compounds, particularly astragaloside IV (AS-IV) and berberine (BBR), have emerged as promising candidates. Notably, emerging clinical evidence supports their translational potential: a randomized controlled trial showed that BBR supplementation (0.4 g, three times daily for one month) significantly improved endothelial function, as assessed by flow-mediated dilation (FMD).²² Furthermore, an ongoing clinical trial (Registration number: ITMCTR2025000262) is investigating the efficacy of an AS-IV-containing herbal formulation in reducing carotid intima-media thickness in individuals with early-stage carotid plaque. Preclinical studies have demonstrated that AS-IV enhances insulin sensitivity, regulates lipid metabolism, and reduces oxidative stress.^23,24 In animal models of diabetic vasculopathy, BBR mitigated vascular inflammation and improved microvascular perfusion.²⁵ Despite the growing body of evidence supporting the benefits of AS-IV and BBR, a significant gap remains in the literature regarding a comprehensive analysis of their specific mechanisms in the context of obesity- and diabetes-induced vascular dysfunction. This review aims to address this gap by consolidating the latest research on the therapeutic potential of AS-IV and BBR in managing vascular complications associated with obesity and diabetes. By synthesizing current insights and exploring emerging therapeutic pathways, this study provides a robust foundation for future investigations, underscoring the promise of natural compounds in alleviating vascular dysfunction and improving health outcomes for affected populations.

Latest Findings on AS-IV and BBR in the Treatment of Vascular Dysfunction Associated with Obesity and Diabetes

Astragaloside IV

AS-IV, a bioactive saponin primarily extracted from Astragalus membranaceus (“Huangqi” in Chinese), with the molecular formula C₄₁H₆₈O_14,²⁶ exhibits considerable therapeutic potential in treating obesity- and diabetes-related vascular dysfunction. This is attributed to its anti-inflammatory, anti-apoptotic, antioxidant, and autophagy-enhancing properties, as well as its ability to promote vasodilation, enhance angiogenesis, inhibit cell proliferation, improve cytoskeletal remodeling, and regulate metabolic processes (Figure 1 and Table 1).

Table 1 Overview of Astragaloside IV on Vascular Dysfunction Related to Obesity and Diabetes

Figure 1 Summary of the biological effects of AS-IV in various vascular cell models. Previous studies have investigated the mechanisms of AS-IV in addressing vascular dysfunction using models such as aortas, human umbilical vein endothelial cells (HUVECs), Endothelial progenitor cells (EPCs), and vascular smooth muscle cells (VSMCs). AS-IV has been shown to suppress apoptosis, reduce inflammation, enhance autophagy, exhibit antioxidant properties, promote vasodilation, inhibit proliferation, support angiogenesis, and improve cytoskeletal remodeling. Symbol key: Activation is indicated by arrow lines (→), inhibition by blocker lines (—|). Abbreviations: HUVECs, human umbilical vein endothelial cells; EPCs, Endothelial progenitor cells; VSMC, vascular smooth muscle cell; SIRT1, sirtuin 1; Bax, BCL2-associated X; Bcl-2, B-cell lymphoma-2; CaSR, calcium-sensing receptor; LOX-1, lectin-like oxidized LDL receptor; NLRP3, NLR family pyrin domain containing 3; TLR4, Toll-like receptor-4; NF-kB, Nuclear factor kappa-light-chain-enhancer of activated B cells; TRAF6,TNF receptor associated factor 6; IL-1β, interleukin 1β; TNF-α, tumor necrosis factor; PTEN, phosphatase and tensin homolog; PI3K, phosphatidylinositol 3-kinase; AKT, protein kinase B; GSK 3β, glycogen synthase kinase-3 β; Nrf2, nuclear factor E2-related factor 2; Nox2, NADPH oxidase 2; ROS, reactive oxygen species; TGF-β1, transforming growth factor-β1; Smad2, mothers against decapentaplegic homolog 2; JNK, c-Jun N-terminal kinase; SOD, superoxide dismutase; eNOS, endothelial nitric oxide synthase; NO, nitric oxide; PKC, protein kinase C.

In streptozotocin (STZ)-induced diabetic rats, AS-IV improved endothelial function by upregulating endothelial nitric oxide synthase (eNOS) and NO levels, facilitating vasodilation, and reducing pro-inflammatory cytokines such as IL-6 and TNF-α. TLR4, a key member of the toll-like receptor family, activates the classical TLR4/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway, leading to NF-κB p65 translocation into the nucleus and promoting the secretion of pro-inflammatory cytokines. This pathway also activates the NLR family pyrin domain containing 3 (NLRP3) inflammasome.⁴⁴ Similarly, the calcium-sensing receptor (CaSR), a G protein-coupled receptor, plays a significant role in regulating inflammation and activating the NLRP3 inflammasome.⁴⁵ AS-IV alleviated endothelial dysfunction by downregulating TLR4 expression, inhibiting NF-κB p65 translocation, and reducing adhesion molecules (ICAM-1, VCAM-1) levels.²⁷ Furthermore, AS-IV suppressed the NLRP3 inflammasome by downregulating cytokines (IL-1β, IL-18) through inhibition of both the TLR4/NF-κB pathway and CaSR.³⁰ In high-glucose (HG)-treated endothelial cells, AS-IV reduced pro-inflammatory cytokine secretion and enhanced mesenchymal stem cell (MSC)-derived exosomal miR-146a-5p expression, improving cell viability and reducing inflammation by targeting TNF receptor-associated factor 6 (TRAF6) and NF-κB phosphorylation.³⁴

Beyond its anti-inflammatory effects, AS-IV exhibited significant anti-apoptotic benefits in HG-treated human umbilical vein endothelial cells (HUVECs) by reducing the Bax/Bcl-2 ratio and suppressing mitochondrial apoptotic markers, including Cyt-c, cleaved-caspase-9, and cleaved-caspase-3.³⁹ AS-IV also protected pancreatic β-cells from STZ-induced apoptosis by modulating the SIRT1/p53 pathway, essential for regulating apoptosis under stress. SIRT1, a NAD+-dependent deacetylase, deacetylates p53, preventing p53-mediated apoptosis and promoting cell survival.⁴⁶ AS-IV activated SIRT1, which suppressed p53-mediated apoptosis by increasing the expression of the anti-apoptotic protein Bcl-2 and decreasing the levels of pro-apoptotic proteins such as Bax and caspase-3.⁴³ AS-IV further promoted autophagy, a critical process for cellular survival under stress, by upregulating autophagic markers LC3II/I and ATG5. LC3II/I facilitates autophagosome formation, while ATG5 plays a pivotal role in autophagosome maturation, together supporting the clearance of damaged cellular components.³³ Additionally, AS-IV exerted potent antioxidant effects by modulating the protein kinase B (Akt)/GSK3β/Nuclear factor erythroid 2–related factor 2(Nrf2) signaling axis. The Akt/GSK3β pathway is involved in cell survival and metabolic regulation, while Nrf2, a key transcription factor, regulates the expression of antioxidant enzymes, including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px).⁴³

AS-IV also promoted angiogenesis and reinforced endothelial barrier function through multiple mechanisms. Endothelial progenitor cells (EPCs), essential for vascular repair and regeneration, play a critical role in angiogenesis.⁴⁷ In HG-treated EPCs, exosomes derived from AS-IV-treated cells enhanced tube formation and upregulated miR-214, a microRNA known to activate angiogenic signaling by modulating the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and increasing the expression of angiopoietin-1, a protein vital for endothelial cell maturation and vascular integrity.³² AS-IV regulated the miR-210/Nox2/reactive oxygen species (ROS) axis in EPCs, where miR-210, involved in hypoxic responses, reduced oxidative stress by modulating Nox2 and ROS production. This action further promoted angiogenesis and vascular regeneration.³⁵ Additionally, AS-IV stabilized the endothelial barrier by modulating the dynamics of filamentous actin (F-actin), which is essential for maintaining cell structure and integrity. It inhibited protein kinase C (PKC) translocation, a process that can disrupt endothelial function and barrier permeability, thereby enhancing vascular stability.³⁶ In STZ-induced diabetic models and HG-treated endothelial cells, AS-IV restored endothelial function by increasing eNOS levels and reducing calpain-1, an enzyme associated with endothelial dysfunction.²⁸

In metabolic regulation, AS-IV improved glucose and lipid metabolism in high-fat diet (HFD)-fed models by reducing triglyceride and cholesterol levels and enhancing thermogenesis. This was achieved through upregulation of genes such as peroxisome proliferator-activated receptor alpha (PPARα) and uncoupling protein 1 (UCP1), which are involved in fat oxidation and energy expenditure.³⁷ AS-IV alleviated leptin resistance and regulated adipocyte lipolysis, stabilizing lipid storage and mitigating TNF-α-induced disruptions.³⁸ Phosphatase and tensin homolog (PTEN) plays a pivotal role in regulating cellular metabolism and autophagy by modulating the PI3K/Akt signaling pathway.⁴⁸ In insulin-resistant adipocytes, AS-IV enhanced glucose consumption, increased glucose transporter type 4 (GLUT-4) expression, and improved insulin sensitivity through PTEN inhibition and PI3K/Akt activation.⁴¹

Berberine

BBR, a quaternary ammonium alkaloid primarily extracted from Coptis chinensis Franch. (“Huanglian” in Chinese), with the molecular formula [C₂₀H₁₈NO₄]⁴,⁴⁹ exhibits a broad spectrum of beneficial biological activities in treating vascular dysfunction associated with obesity and diabetes. These include inhibiting AGE formation, promoting vasodilation, anti-apoptosis, anti-inflammation, antioxidant effects, enhancing autophagy, improving glucose and lipid metabolism, and enhancing insulin sensitivity (Figure 2 and Table 2).

Table 2 Overview of berberine on Vascular Dysfunction Related to Obesity and Diabetes

Figure 2 Summary of the biological effects of BBR in various vascular cell models. Previous studies have investigated the mechanisms of BBR in alleviating vascular dysfunction using models such as adipocytes, MS1 cells, HUVECs, aortas, and mesenteric arteries. BBR has been shown to suppress apoptosis, exhibit antioxidant and anti-inflammatory effects, promote vasodilation, improve insulin resistance, and enhance autophagy. Symbol key: Activation is indicated by arrow lines (→), inhibition by blocker lines (—|). Abbreviations: AGEs, advanced glycation end products; AMPK, AMP-activated protein kinase; IKK, IκB kinase; MCP-1, monocyte chemotactic protein-1; JNK, c-Jun N-terminal kinase.

BBR improved vascular function in HFD- and STZ-induced diabetic rats by enhancing NO bioavailability, crucial for maintaining endothelial function and vascular tone. It increased serum NO levels and promoted endothelium-dependent relaxation, primarily through upregulation of eNOS expression.⁵¹ BBR also reduced oxidative stress by downregulating Nox4, a subunit of NADPH oxidase, which contributes to the production of ROS and endothelial dysfunction in diabetes.⁵⁴ Furthermore, BBR significantly inhibited AGE formation, improving HG-induced endothelial cell injury in microvascular models.⁵⁰ In palmitate or HG-treated HUVECs, BBR similarly enhanced eNOS activation and NO production through the AMP-activated protein kinase (AMPK) pathway.^52,54 AMPK, a critical regulator of cellular energy balance, when activated, increases eNOS activity, thereby contributing to NO production and improving endothelial function.⁶¹ In diabetic rats, BBR also enhanced acetylcholine-induced vasodilation in mesenteric arteries and improved insulin-induced vasodilation via the PI3K/Akt signaling pathway, a key mechanism for endothelial function and insulin sensitivity.⁵³

Beyond its vascular benefits, BBR exerts significant anti-inflammatory effects and improves insulin resistance, both of which are key factors in obesity and diabetic vascular dysfunction. In HG-treated HUVECs, BBR activated AMPK, promoting NO production and inhibiting monocyte adhesion by suppressing NF-κB activation and reducing the expression of adhesion molecules such as VCAM-1 and ICAM-1, thereby mitigating inflammation.⁵² In HFD-induced mice, BBR improved insulin sensitivity and reduced macrophage infiltration, particularly M1 macrophages, into adipose tissue. M1 macrophages, being pro-inflammatory, play a pivotal role in the development of insulin resistance.⁶² BBR also reduced levels of inflammatory cytokines, including MCP-1, IL-6, and TNF-α. This anti-inflammatory effect is associated with the inhibition of key inflammatory kinases, such as c-Jun N-terminal kinase (JNK) and IκB kinase β (IKKβ), which are involved in NF-κB activation and inflammatory responses.⁶³ Furthermore, BBR reduced p65 expression, further alleviating inflammation and macrophage chemotaxis.⁵⁵

In both HFD-fed C57BL/6J and Sirt1+/− mice, BBR upregulated SIRT1 expression, activating AMPK and reducing both local and systemic inflammation, thereby improving insulin resistance.⁵⁷ Additionally, BBR modulated macrophage polarization in adipose tissue, shifting them towards an anti-inflammatory phenotype, and activated SIRT3, a mitochondrial deacetylase that mitigates adipose tissue remodeling and miR-155-5p secretion, providing further protection against insulin resistance.⁵⁸ In palmitic acid-treated 3T3-L1 adipocytes, BBR increased the expression of insulin receptor substrate-1 (IRS-1) and PI3K p85 while inhibiting IRS-1 and IKKβ phosphorylation, thereby preventing NF-κB activation.⁵⁹ Co-treatment with BBR and insulin in HG/HF-treated HUVECs enhanced phosphorylation of the insulin receptor (InsR), Akt, and eNOS, suggesting that BBR enhances insulin receptor-mediated signaling.⁵³ In HFD-induced mice, BBR also reduced miR-27a levels in both serum and adipocyte supernatants, significantly alleviating insulin resistance linked to elevated miR-27a.⁶⁰ These findings further support BBR’s anti-inflammatory effects and its capacity to improve insulin signaling.

BBR also promotes improvements in glucose and lipid metabolism. In HFD and STZ-induced diabetic rats, BBR reduced fasting blood glucose (FBG), triglycerides, and 2-hour glucose levels in the oral glucose tolerance test (OGTT), indicating metabolic improvements.⁵³ Furthermore, BBR promoted adipocyte differentiation and decreased lipid accumulation in 3T3-L1 adipocytes by modulating key regulators such as peroxisome proliferator-activated receptors (PPARs) and positive transcription elongation factor b (P-TEFb).⁵⁶ PPARs are nuclear hormone receptors that regulate lipid metabolism, adipogenesis, and insulin sensitivity,⁶⁴ while P-TEFb regulates gene transcription related to adipocyte function and lipid metabolism.⁶⁵ BBR also reduced body weight and fat percentage, improving serum parameters, including FBG, total cholesterol, triglycerides, and LDL-C in palmitic acid-treated adipocytes.⁶⁰ Additionally, BBR enhanced autophagy and promoted cell viability in HG/HF-treated HUVECs, as evidenced by an increased LC3B-II/LC3B-I ratio, a key marker of autophagy, and a reduction in p62 expression, a substrate of autophagic degradation and indicator of impaired autophagic flux.⁵³

Complications of Obesity and Diabetes

Cardiovascular Disease Related to Obesity and Diabetes

Cardiovascular disease (CVD) is an increasingly prevalent public health issue, particularly in the context of rising global rates of obesity and diabetes.⁶⁶ These metabolic disorders are strongly associated with key CVD risk factors, including hyperglycemia, insulin resistance, dyslipidemia, hypertension, and systemic inflammation.⁶⁷ In diabetic individuals, chronic hyperglycemia and metabolic dysregulation contribute to vascular damage through mechanisms such as oxidative stress, AGE formation, endothelial dysfunction, and persistent low-grade inflammation.⁶⁸ These pathological processes collectively lead to a range of cardiovascular complications, including atherosclerosis, hypertension, myocardial infarction, stroke, and heart failure. Moreover, obesity exacerbates these risks by promoting adipose tissue expansion and remodeling, which increases the secretion of pro-inflammatory cytokines and places additional strain on the cardiovascular system.^69,70

Astragaloside IV

AS-IV offers multiple therapeutic benefits in CVDs associated with obesity and diabetes through the modulation of several signaling pathways that regulate lipid metabolism, oxidative stress, cardiac energy metabolism, inflammation, autophagy, and endothelial function. It regulates lipid metabolism by lowering total cholesterol, triglycerides, and LDL-C levels while increasing HDL-C,^71,72 thus promoting vascular health. AS-IV also alleviates oxidative stress by inhibiting Nox4 and modulating the TGF-β1/Smad2 signaling pathway.⁴⁰ The TGF-β1/Smad2 pathway plays a critical role in fibrosis and endothelial dysfunction,⁷³ and its regulation by AS-IV helps protect against vascular damage. In diabetic cardiomyopathy, AS-IV enhances cardiac energy metabolism by upregulating peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and nuclear respiratory factor 1 (NRF1),⁷⁴ both of which are key regulators of mitochondrial biogenesis and oxidative metabolism.⁷⁵ Additionally, AS-IV prevents ferroptosis by downregulating CD36 expression,⁷⁶ a fatty acid transporter involved in lipid peroxidation.⁷⁷ AS-IV further modulates mitogen-activated protein kinase (MAPK) signaling by inhibiting JNK and p38 pathways while promoting extracellular signal-regulated kinase (ERK) activation.^78,79 JNK and p38 are associated with stress and inflammation,⁸⁰ while ERK activation promotes cell survival and proliferation,⁸¹ thus improving cardiac function and protecting against apoptosis.

AS-IV also enhances endothelial function by promoting NO signaling and cyclic guanosine monophosphate (cGMP) production.^26,82 Additionally, it improves hypothalamic leptin sensitivity by increasing leptin receptor mRNA and pro-opiomelanocortin (POMC) expression, while downregulating inhibitory factors such as suppressor of cytokine signaling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B).⁸³ POMC plays a role in energy homeostasis, and the downregulation of SOCS3 and PTP1B (both negative regulators of leptin signaling) aids in metabolic balance.⁸⁴ Moreover, AS-IV exerts anti-inflammatory effects through upregulation of the α7 nicotinic acetylcholine receptor (α7nAChR) and inhibition of the IKKβ/NF-κB pathway, mechanisms that help prevent obesity-associated hypertension.⁸³ The α7nAChR is a key component of the cholinergic anti-inflammatory pathway,⁸⁵ while the IKKβ/NF-κB pathway is central to inflammation, making its inhibition essential for reducing inflammatory responses. Additionally, AS-IV enhances autophagy in vascular smooth muscle cells,⁸⁶ reduces inflammation via the PI3K/Akt/mTOR pathway, and modulates gut microbiota to promote beneficial bacterial populations⁸⁷ (Table 3).

Table 3 Overview of Astragaloside IV and berberine on Cardiovascular Disease of Related to Obesity and Diabetes

Berberine

BBR exerts therapeutic effects through a network of pathways that regulate lipid metabolism, vascular inflammation, gut health, cardiac function, and oxidative stress, underscoring its potential in managing complications associated with obesity and diabetes. It improves lipid and glucose metabolism, reduces vascular inflammation, and attenuates atherogenesis in diabetic apoE-/- mice by enhancing interactions between Krüppel-like factor 16 (KLF16) and PPARα.⁹⁰ KLF16, a transcription factor involved in lipid metabolism and endothelial function,⁹⁸ and PPARα, which regulates fatty acid oxidation and inflammation,⁹⁹ play pivotal roles in BBR’s vascular protective effects through their interaction. BBR also promotes gut health by enriching beneficial microbiota, such as Akkermansia spp., helping to mitigate metabolic endotoxemia and inflammation.^91,92 In diabetic rat models, BBR reduced blood glucose and blood pressure, improved vascular function, and activated large conductance calcium-activated potassium (BK_Ca) channels.⁹³ BK_Ca channels, critical for regulating vascular tone and endothelial function,¹⁰⁰ contribute to enhanced vascular health when activated by BBR.

Additionally, BBR improved cardiac function and reduced fibrosis in db/db mice by modulating the mTOR/mitochondrial reactive oxygen species (mtROS) axis and inhibiting pyroptosis.⁹⁴ The mTOR/mtROS pathway is involved in cellular energy metabolism and oxidative stress regulation, with dysregulation contributing to cardiac dysfunction and fibrosis.¹⁰¹ Pyroptosis, a form of programmed cell death associated with inflammation,¹⁰² was mitigated by BBR, providing further protection to cardiac tissue. In diabetic cardiomyopathy, BBR reduced cardiac fibrosis and dysfunction via insulin-like growth factor 1 receptor (IGF-1R) signaling in cardiac fibroblasts.⁹⁵ IGF-1R signaling is essential for cell growth, survival, and tissue repair, making it a crucial target in preventing cardiac fibrosis.¹⁰³ BBR also alleviated cardiomyocyte hypertrophy by activating PPARα and modulating NO signaling.⁹⁶ Furthermore, BBR protected against HG-induced platelet hyper-reactivity and apoptosis by modulating oxidative stress pathways.⁹⁷ These effects contribute to reducing thrombosis and vascular injury, common complications in diabetes (Table 3).

Diabetic Retinopathy

Diabetic retinopathy (DR) is a prevalent and severe microvascular complication of diabetes mellitus (DM), representing the leading cause of vision impairment and blindness among working-age adults globally.¹⁰⁴ Its pathogenesis is closely associated with chronic hyperglycemia, which induces progressive damage to the retinal microvasculature, including endothelial dysfunction, capillary basement membrane thickening, pericyte loss, and increased vascular permeability.¹⁰⁵ These cellular and molecular alterations lead to ischemia, hypoxia, and inflammation in the retina, triggering a cascade of events that culminate in the hallmark features of DR: microaneurysms, retinal hemorrhages, hard exudates, and, ultimately, proliferative retinopathy.¹⁰⁶ Additionally, oxidative stress,^107,108 chronic low-grade inflammation,^109,110 and an upregulated renin-angiotensin system (RAS)¹¹¹ exacerbate these vascular changes, promoting pathological neovascularization and fibrovascular proliferation, which significantly heighten the risk of vision loss.

Astragaloside IV

AS-IV exerts protective effects against DR through a combination of antioxidant, anti-inflammatory, and anti-apoptotic mechanisms, targeting multiple signaling pathways and molecular mediators. In vitro studies on retinal capillary endothelial cells (RCECs) demonstrated that AS-IV enhanced cell viability, reduced glucose transporter-1 (GLUT-1) expression, and decreased oxidative stress markers such as hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). It also boosted antioxidant enzyme activity, increased glutathione levels, and lowered Nox4 expression,¹¹² thus reducing oxidative damage in retinal cells. In retinal ganglion cells (RGCs), AS-IV improved cell viability, reduced oxidative stress, and promoted retinal layer thickness. Network pharmacology identified additional potential targets for AS-IV, including hypoxia-inducible factor 1-alpha (HIF-1α) and Akt1.¹¹³ HIF-1α is critical for cellular adaptation to hypoxia,¹¹⁴ while Akt1 plays a pivotal role in cell survival, growth, and metabolism.¹¹⁵

In diabetic rats, AS-IV prevented ferroptosis in retinal pigment epithelial (RPE) cells by promoting the expression of SIRT1 and Nrf2, along with increasing miR-138-5p levels.¹¹⁶ SIRT1 is involved in mitochondrial function and cellular stress responses, while Nrf2 regulates antioxidant defenses, both crucial for cell survival under oxidative stress conditions. miR-138-5p is linked to ferroptosis regulation,¹¹⁷ further enhancing AS-IV’s protective effect on RPE cells. Moreover, AS-IV functioned as an aldose reductase inhibitor, reducing ERK1/2 phosphorylation and NF-κB activation, both critical in inflammatory and apoptotic pathways in retinal cells.¹¹⁸ It also protected RPE cells from apoptosis by modulating pro-apoptotic proteins (eg, Bax and active caspases) and anti-apoptotic proteins (eg, Bcl-2 and FasL). AS-IV upregulated miR-128 expression, which regulates apoptosis and cell survival in retinal cells¹¹⁹ (Table 4).

Table 4 Overview of Astragaloside IV and berberine on Diabetic Retinopathy

Berberine

BBR also demonstrates significant therapeutic potential for DR by reducing hyperglycemic damage, inhibiting angiogenesis and inflammation, and modulating immune responses while promoting cellular survival and autophagy in retinal cells. It effectively lowered FBG and triglyceride levels, thereby mitigating hyperglycemic damage to retinal tissue.¹²⁰ BBR inhibited the expression of HIF-1α and vascular endothelial growth factor (VEGF), key factors involved in angiogenesis and vascular permeability, via the AKT/mTOR signaling pathway.^121,122 Additionally, BBR modulated immune responses by increasing regulatory T cells (Tregs) and decreasing pro-inflammatory Th17 cells, fostering a balanced immune environment.¹²³ This immune modulation helped reduce the inflammatory responses that contribute to retinal damage in DR. BBR also protected retinal Müller cells from apoptosis, a process often aggravated by hyperglycemia, and promoted autophagy, further preserving retinal health under diabetic conditions.¹²⁴ (Table 4)

Diabetic Nephropathy

Diabetic nephropathy (DN) is a severe microvascular complication of DM, characterized by progressive kidney damage that often progresses to end-stage renal disease (ESRD).¹²⁵ DN is a leading cause of chronic kidney disease globally, with patients facing significant morbidity and mortality due to the gradual decline in renal function,¹²⁶ as well as an increased risk of CVD and other comorbidities.¹²⁷ Pathologically, DN is marked by glomerular hypertrophy, basement membrane thickening, mesangial matrix expansion, and tubulointerstitial fibrosis, all of which contribute to proteinuria and a reduction in glomerular filtration rate (GFR).^128,129 The pathogenesis of DN is multifactorial, involving hyperglycemia-induced oxidative stress, inflammation, accumulation of AGEs, and dysregulation of various signaling pathways.^130,131 These processes result in cellular injury within the renal microvasculature and impair the function of podocytes, mesangial cells, and endothelial cells.

Astragaloside IV

AS-IV has demonstrated significant renoprotective effects in DN by targeting multiple pathways involved in oxidative stress, inflammation, apoptosis, and fibrosis.^132–137 In various DN models, AS-IV reduced albuminuria, serum creatinine levels, and mesangial expansion by inhibiting key signaling pathways such as MEK1/2-ERK1/2-RSK2, TUG1/TRAF5, and Akt/mTOR.^138–140 The MEK1/2-ERK1/2-RSK2 pathway is critical for cell survival, inflammation, and fibrosis, while the TUG1/TRAF5 axis regulates inflammation and immune responses in kidney cells. The Akt/mTOR pathway is involved in cell growth and metabolism, and AS-IV’s inhibition of these pathways helped mitigate renal damage in DN.

In podocytes exposed to high glucose, AS-IV enhanced the expression of klotho, a protein that suppresses oxidative stress and pyroptosis by inhibiting the NF-κB and NLRP3 inflammasome pathways.¹⁴¹ In palmitic acid-bound BSA-treated NRK-52E cells, AS-IV inhibited mitochondrial dysfunction and inflammation, further supporting its protective effects on renal cells under diabetic conditions.¹⁴² Additionally, AS-IV promoted autophagy and reduced apoptosis by activating AMP-activated protein kinase alpha (AMPKα) and sarco/endoplasmic reticulum calcium ATPase 2b (SERCA2b).¹⁴³ AMPKα is a critical regulator of cellular energy balance, while SERCA2b plays a role in maintaining intracellular calcium homeostasis,¹⁴⁴ both contributing to cellular protection in the kidney.

AS-IV also enhanced gut-renal interactions by restoring intestinal barrier function and promoting beneficial gut microbiota while reducing renal and intestinal ferroptosis in db/db mice.¹⁴⁵ Ferroptosis, an iron-dependent form of cell death, plays a role in both renal and intestinal damage in DN.¹⁴⁶ By modulating histone modifications and reducing markers of endoplasmic reticulum (ER) stress, including eukaryotic initiation factor-2α (eIF2α), Protein Kinase RNA-like Endoplasmic Reticulum Kinase (PERK), JNK, Glucose Regulated Protein 78 (GRP78), and cleaved Activating Transcription Factor 6 (ATF6),^147,148 AS-IV upregulated anti-apoptotic factors and downregulated pro-inflammatory cytokines such as TNF-α and MCP-1.^149,150 In endothelial cells, AS-IV preserved barrier integrity by activating the AKT-GSK3 pathway,¹⁵¹ crucial for regulating cell survival, migration, and vascular integrity. Additionally, AS-IV enhanced NO synthesis via modulation of eNOS,¹⁵² vital for maintaining endothelial function and vasodilation (Table 5).

Table 5 Overview of Astragaloside IV and berberine on Diabetic Nephropathy

Berberine

BBR exhibits therapeutic efficacy in DN by reducing inflammation and oxidative stress and alleviating histopathological changes. It lowered levels of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), markers of endothelial activation and inflammation.¹⁵⁴ Furthermore, BBR inhibited the RhoA/ROCK signaling pathway and NF-κB activity, both critical for regulating fibronectin accumulation and renal inflammation.¹⁵⁵ The RhoA/ROCK pathway governs cell contraction, motility, and fibrosis,¹⁶¹ while NF-κB serves as a central mediator of inflammatory responses. Modulating these pathways, BBR reduced fibrosis and inflammation in DN. Additionally, BBR mitigated tubulointerstitial fibrosis and epithelial-to-mesenchymal transition (EMT) in kidney cells. EMT involves renal epithelial cells losing their characteristics and acquiring a mesenchymal phenotype, contributing to fibrosis and tissue remodeling in DN.¹⁶² BBR downregulated NLRP3 inflammasome activation, a key factor in inflammation, and inhibited TGF-β1 transfer from mesangial cells, further protecting against fibrosis and EMT.^156–158

Moreover, BBR reduced collagen synthesis by inhibiting the p38 mitogen-activated protein kinase (p38MAPK) pathway and modulated G protein-coupled receptor kinases (GRKs) to increase cyclic adenosine monophosphate (cAMP) levels, further contributing to its renoprotective effects.¹⁵⁹ Additionally, BBR decreased aldose reductase activity, lowering oxidative stress and extracellular matrix synthesis.¹⁶⁰ Aldose reductase, an enzyme involved in the polyol pathway, is activated under hyperglycemic conditions and contributes to oxidative damage.¹⁶³ Inhibiting this enzyme helped reduce oxidative stress, a major contributor to kidney injury in DN (Table 5).

Discussion

The increasing global prevalence of obesity and diabetes, alongside their associated vascular complications, highlights the urgent need for effective therapeutic strategies to manage vascular dysfunction in these conditions. As endothelial dysfunction plays a central role in the pathogenesis of diabetic vascular complications, targeting the underlying mechanisms of vascular injury is essential to prevent the further progression of diseases such as CVD, DR, and DN. In this context, AS-IV and BBR, two bioactive compounds with distinct mechanisms of action, present promising therapeutic potential for mitigating vascular dysfunction associated with obesity and diabetes.

Mechanistic Insights and Therapeutic Potentials

The therapeutic potential of AS-IV and BBR in treating vascular dysfunction and associated complications in obesity and diabetes is evident through their complementary mechanisms. Both compounds target inflammation, oxidative stress, endothelial dysfunction, and insulin resistance, providing promising treatment options for CVDs, DR, and nephropathy (Supplementary Table 1).

Vascular Dysfunction

AS-IV and BBR enhance endothelial function by promoting NO production and reducing oxidative stress. They achieve this by upregulating eNOS and inhibiting NADPH oxidase. Both compounds also improve insulin sensitivity; AS-IV activates the PI3K/Akt pathway, while BBR activates AMPK, leading to enhanced glucose uptake. AS-IV reduces pro-inflammatory cytokines and adhesion molecules via TLR4/NF-κB inhibition, while BBR modulates macrophage polarization through SIRT1 and AMPK activation. Both compounds promote autophagy, with AS-IV utilizing the PI3K/Akt/mTOR pathway and BBR relying on AMPK signaling. While AS-IV focuses on angiogenesis and anti-apoptotic effects, BBR targets inhibiting AGEs formation and macrophage polarization, highlighting their complementary roles in vascular repair and metabolic regulation.

Cardiovascular Protection

AS-IV and BBR both improve lipid metabolism and reduce vascular inflammation. AS-IV increases HDL-C and reduces LDL-C, whereas BBR modulates KLF16 and PPARα interactions to enhance lipid metabolism. AS-IV acts through the PI3K/Akt/mTOR and α7nAChR pathways, while BBR reduces metabolic endotoxemia by modulating gut microbiota. In terms of cardiac protection, AS-IV promotes energy metabolism and reduces oxidative stress through Nox4 and TGF-β1/Smad2 pathways, whereas BBR protects against cardiac fibrosis via the mTOR/mtROS axis. AS-IV also prevents ferroptosis, while BBR modulates PPARα and NO signaling to reduce cardiomyocyte hypertrophy.

Retinal and Renal Protection

In DR, AS-IV protects retinal cells through enhanced antioxidant enzyme activity and inhibition of apoptosis, particularly through modulation of pro-apoptotic proteins. BBR also improves retinal health by reducing oxidative damage, promoting autophagy, and modulating the immune response by increasing regulatory T cells. Both compounds inhibit angiogenesis, with BBR acting through the Akt/mTOR pathway. AS-IV targets ferroptosis resistance, while BBR inhibits aldose reductase and reduces inflammation. In DN, both compounds reduce inflammation and oxidative stress. AS-IV enhances klotho expression and modulates the Akt/mTOR pathway to alleviate fibrosis, while BBR inhibits TGF-β1 and NLRP3 inflammasome activation to prevent fibrosis.

Challenges and Future Directions

Despite promising preclinical findings, several obstacles must be overcome before AS-IV and BBR can be widely incorporated into clinical practice, particularly their limited bioavailability. The absolute bioavailability of AS-IV is only 3.66% in rats and 7.4% in beagle dogs,¹⁶⁴ while BBR’s bioavailability in rats is even lower, at 0.68%.¹⁶⁵ Another significant challenge lies in the standardization of dosing regimens. Both clinical and preclinical studies have utilized varying doses and formulations, leaving the optimal therapeutic dose undetermined. For instance, a study on AS-IV’s protective effects against endothelial dysfunction assessed doses of 40 mg/kg/day and 80 mg/kg/day.¹⁶⁶ Conversely, research on podocyte apoptosis in DN models administered a substantially lower dose of 5 mg/kg/day,¹⁴⁰ demonstrating considerable variability in dosing strategies. In BBR research, experiments with HFD and STZ-induced diabetic rats used doses of 50, 100, and 150 mg/kg/day.¹⁶⁷ Studies examining BBR’s lipid-lowering efficacy, particularly in combination with resveratrol, utilized as low as 30 mg/kg/day.¹⁶⁸ This wide dosage range emphasizes the need for further investigations to determine the most effective and safe doses for both AS-IV and BBR.

To address bioavailability limitations, innovative drug delivery systems such as nanoparticle-based formulations and absorption enhancers are under exploration. A water-soluble AS-IV derivative, astragalosidic acid (LS-102), demonstrated nearly 500-fold greater transepithelial permeability compared to AS-IV.¹⁶⁹ Hyaluronate-based liposomes encapsulating BBR have also enhanced its lipophilicity and bioavailability.¹⁷⁰ Additionally, chitosan-alginate nanoparticles loaded with BBR increased oral bioavailability by 4.1-fold in rats relative to a standard BBR suspension.¹⁷¹ Absorption enhancers like sodium caprate and sodium deoxycholate significantly boosted BBR absorption, elevating plasma concentrations by 41.1-fold and 35.3-fold, respectively.¹⁷² While these approaches show potential, further research is necessary to refine these strategies for clinical application.

While both AS-IV and BBR exhibit complementary mechanisms, their potential synergism remains underexplored. Three critical questions warrant immediate attention: (1) Do AS-IV and BBR interact pharmacokinetically or pharmacodynamically when co-administered? (2) Can optimize combined dosing ratios enhance efficacy without increasing toxicity in multifactorial vascular dysfunction models? (3) Can advance delivery systems mitigate the bioavailability limitations of dual therapy? In parallel with these mechanistic inquiries, the establishment of standardized dosing regimens is essential, which requires rigorous pharmacodynamic studies, particularly considering interactions with conventional antidiabetic medications. Furthermore, large-scale randomized trials are necessary to assess the long-term safety profiles of this combination in comorbid populations. Addressing these gaps will bridge the gap between mechanistic insights and clinically applicable combination strategies.

Conclusion

AS-IV and BBR represent two promising natural compounds with substantial potential for managing vascular dysfunction in obesity and diabetes. While preclinical data are promising, clinical evidence remains limited. The combination of these compounds may offer a comprehensive approach to addressing both the metabolic and vascular aspects of these diseases. However, challenges such as bioavailability, optimal dosing, combinatorial efficacy, and long-term safety must be resolved. Overcoming these hurdles could position AS-IV and BBR as integral components in clinical strategies aimed at combating the growing global burden of obesity, diabetes, and their vascular complications.