The gut microbiota metabolizes undigested dietary components into SCFAs, primarily acetate (60%–70%), propionate (15%–20%), and butyrate (10%–15%), which collectively regulate intestinal barrier integrity, metabolic homeostasis, and immune function (Morrison and Preston, 2016). Acetate serves as both an energy substrate and signaling molecule, with experimental studies demonstrating its capacity to activate hepatic free fatty acid receptor 2 (FFAR2), thereby improving insulin sensitivity and attenuating lipid accumulation in MASLD models (Aoki et al., 2021). Butyrate exerts multifaceted protective effects through enhancing TJ protein expression, and inhibiting macrophage activation and inflammatory factor production, thereby reducing endotoxin translocation and achieving attenuation of secondary liver injury (Liu et al., 2014). SCFAs further reinforce intestinal barrier function by stimulating interleukin-18 (IL-18) secretion through NLRP3 inflammasome activation, while their portal circulation-mediated hepatic delivery directly suppresses lipogenic pathways via sterol regulatory element-binding protein 1c (SREBP1c) downregulation (Macia et al., 2015; Dai et al., 2020).

Dysbiosis-induced SCFA depletion exacerbates MASLD progression through impaired glucagon-like peptide-1 (GLP-1) secretion, elevated intestinal permeability, and aggravated endotoxemia. Preclinical evidence indicates that high-fat diet-fed mice exhibit marked reductions in SCFA-producing bacteria and corresponding metabolite levels, which correlate with accelerated hepatic steatosis and fibrosis (Huang et al., 2020). Therapeutic restoration of SCFAs through dietary modulation or direct supplementation demonstrates significant metabolic benefits, including reduction in hepatic triglyceride content and decrease in fibrotic markers, highlighting their potential as therapeutic targets in MASLD management (Baumann et al., 2020; Zhao et al., 2021).

BAs undergo hepatic biosynthesis from cholesterol followed by conjugation with taurine/glycine prior to biliary secretion. Approximately 95% of secreted BAs are reabsorbed through ileal enterocytes, completing the enterohepatic circulation - a process critically modulated by gut microbial biotransformation. Intestinal microbiota mediate BA deconjugation and 7α-dehydroxylation, converting primary BAs (cholic acid [CA], chenodeoxycholic acid [CDCA]) into secondary forms (deoxycholic acid [DCA], lithocholic acid [LCA]) with distinct physicochemical properties (Tilg et al., 2022). Clinical metabolomic analyses reveal MASLD patients exhibit 4-fold elevated serum DCA compared to healthy controls, establishing BA dysmetabolism as a hallmark of disease progression (Jiao et al., 2018).

The signaling potency of BAs is governed by receptor specificity: FXR demonstrates nanomolar affinity for CDCA versus millimolar responses to DCA, while G-protein-coupled BA receptor, Gpbar1 (TGR5) is preferentially activated by LCA (Inagaki et al., 2006; Safari and Gerard, 2019; Merlen et al., 2020). This ligand-receptor selectivity implies that dysbiosis-induced BA compositional shifts can dysregulate hepatic metabolism through altered FXR/TGR5 signaling cascades. Mechanistically, FXR activation preserves intestinal barrier function by upregulating tight junction proteins and suppressing bacterial translocation, whereas TGR5 signaling modulates macrophage polarization towards anti-inflammatory phenotypes (Yamada et al., 2018; Wu et al., 2021).

Lipopolysaccharide (LPS), a glycolipid constituent of Gram-negative bacterial membranes, functions as a potent pathogen-associated molecular pattern that drives chronic low-grade inflammation in MASLD pathogenesis (Ji et al., 2019). Hepatic recognition of circulating LPS occurs through a multi-receptor complex comprising Toll-like receptor 4 (TLR4), myeloid differentiation protein-2 (MD-2), and co-receptor CD14, with lipopolysaccharide-binding protein (LBP) facilitating endotoxin transfer to this signaling complex. Activation of this pathway in Kupffer cells triggers NF-κB-mediated proinflammatory cytokine production, establishing a microenvironment conducive to MASLD progression (Ferro et al., 2020; Wang L. et al., 2024). Besides, LPS activates the NLRP3 inflammasome via TLR4 signaling in adipocytes, triggering IL-1β/IL-18 release that drives adipose tissue inflammation and fibrosis. Experimental NLRP3 inhibition suppresses LPS-induced proinflammatory cytokine production and downregulates collagen/extracellular matrix (ECM) remodeling genes, demonstrating its dual therapeutic potential for mitigating metabolic inflammation and fibrotic progression in obesity-related disorders (Liu et al., 2016; Unamuno et al., 2021).

Beyond its pro-inflammatory effects, LPS demonstrates dual regulatory roles in liver pathophysiology. LBP deficiency exacerbates hepatic steatosis despite attenuating inflammation - evidenced by excessive fat deposition in LBP−/− mice compared to wild-type controls (Zhu et al., 2024). This dichotomy underscores the complex interplay between endotoxin signaling and metabolic regulation. The intestinal barrier emerges as both source and target of LPS-mediated injury. Physiological concentrations of LPS compromise TJ integrity through TLR4-dependent process, creating a vicious cycle of endotoxemia and barrier dysfunction (Guo et al., 2013).

The gut microbiota serves as the primary source of endogenous ethanol. Zhu et al. (2013) conducted a comparative analysis of gut microbial composition and peripheral blood ethanol levels among children with MASH, obesity, and healthy controls. Their findings revealed significant alterations in gut microbiota profiles in both obese and MASH groups compared to healthy individuals, with MASH patients exhibiting elevated abundances of ethanol-producing bacterial taxa and markedly higher circulating ethanol concentrations. These observations imply that microbiota-derived endogenous ethanol may function as a hepatotoxic agent contributing to MASLD initiation and progression.

Emerging evidence has elucidated mechanistic links between endogenous ethanol and MASLD pathogenesis. First, ethanol upregulates cytochrome P450 2E1 (CYP2E1) enzymatic activity, amplifying reactive oxygen species (ROS) generation. This process induces hepatic oxidative stress (OS) and inflammatory cascades, thereby exacerbating hepatocellular injury and accelerating MASLD progression (Aljomah et al., 2015; Abdelmegeed et al., 2017). Second, ethanol directly impairs mitochondrial function in hepatocytes, a hallmark of advanced MASLD (Chen X. et al., 2020). Third, ethanol exacerbates liver damage indirectly through its metabolite acetaldehyde, which induces oxidative stress and disrupts intercellular TJs (Liu et al., 2022). As demonstrated by Dunagan et al. (2012), acetaldehyde-mediated TJ dysfunction increases intestinal paracellular permeability, facilitating translocation of microbial components or metabolites into the portal circulation. This process triggers systemic inflammation and further aggravates hepatic injury, establishing a vicious cycle in MASLD progression.

Choline, an essential nutrient predominantly sourced from dietary components including red meat, eggs, and nuts, plays a critical role in hepatic lipid metabolism and regulates BAs enterohepatic circulation (Xiang et al., 2022). Emerging evidence implicates choline deficiency as a contributor to MASLD progression. As a key substrate for very-low-density lipoprotein (VLDL) biosynthesis, insufficient choline availability reduces hepatic VLDL secretion, leading to triglyceride (TG) accumulation and subsequent hepatocyte injury (Jacob et al., 2021). This mechanistic insight underpins the widespread use of methionine-choline-deficient (MCD) diets to induce MASH in preclinical models, where resultant phenotypes are closely associated with intestinal inflammatory responses (Matthews et al., 2021).

Gut microbiota-mediated metabolism further links choline to MASLD pathogenesis. Microbial conversion of choline to trimethylamine (TMA) is followed by hepatic oxidation via flavin-containing monooxygenase 3 (FMO3), generating trimethylamine N-oxide (TMAO). Clinical studies demonstrate elevated TMAO levels correlating with MASLD severity and MASH risk in humans (Leon-Mimila et al., 2021). Experimental models reveal that TMAO administration exacerbates hepatic steatosis by enhancing de novo lipogenesis and impairing BA-activated FXR signaling (Tan et al., 2019). Furthermore, TMAO aggravates metabolic dysregulation through multiple pathways: disrupting intestinal barrier integrity, compromising hepatic endothelial function, and modulating macrophage polarization toward proinflammatory phenotypes (Nian et al., 2024). While these findings highlight TMAO’s pathogenic role, its potential as a therapeutic target for MASLD warrants rigorous investigation.

Hepatic disturbances in amino acid and lipid metabolism promote fatty acid deposition, triggering OS and hepatocellular injury that accelerates MASLD progression (Deng et al., 2024). Comparative analyses of serum amino acid profiles among healthy controls, MASLD patients, and hepatic fibrosis cases revealed elevated circulating levels of branched-chain amino acids (BCAAs), glutamic acid (Ekstrand et al., 2017), and alanine (Ala) in fibrosis patients, with MASLD subjects showing particularly pronounced Ala elevation. These metabolic alterations demonstrate strong correlations with insulin resistance and hepatic metabolic dysfunction (Hasegawa et al., 2020).

Mechanistic studies elucidate BCAA-mediated hepatotoxicity through dual tissue-specific pathways. In adipocytes, BCAAs activate AMPKα2 to stimulate lipolysis, thereby increasing plasma free fatty acid (Lena et al., 2005) release. Concurrently, hepatic BCAAs activate mammalian target of rapamycin (mTOR) signaling, which inhibits FFA-to-TG conversion, exacerbates FFA-induced lipotoxicity, suppresses hepatocyte autophagy, and promotes apoptosis, collectively driving liver injury (Zhang et al., 2016).

Aromatic amino acids (AAAs) - tryptophan (Trp), phenylalanine (Phe), and tyrosine (Tyr) - exert bidirectional regulatory effects on MASLD pathogenesis. Hepatic Trp metabolism via tryptophan 2,3-dioxygenase (TDO2) and indoleamine 2,3-dioxygenase (IDO) generates kynurenine (Kyn), which activates aryl hydrocarbon receptor (AHR) signaling to promote obesity-associated hepatic steatosis (Rojas et al., 2021). Conversely, gut microbiota metabolize Trp into protective indole derivatives including indole-3-acetic acid (IAA), indole-3-propionic acid (IPA), and tryptamine (Dai et al., 2020). Notably, IPA demonstrates therapeutic potential by ameliorating gut dysbiosis, enhancing intestinal barrier integrity to prevent endotoxin translocation, and suppressing NF-κB-mediated proinflammatory cytokine release (Zhao et al., 2019).

These findings collectively highlight that dysregulated amino acid metabolism - through both hepatotoxic and protective pathways - constitutes a key mechanistic axis in MASLD development. Targeted modulation of these metabolic networks may yield novel therapeutic strategies for MASLD management.

In summary, in the condition of gut microbiota dysbiosis, various bacterial metabolites such as SCFAs, Bas, LPS, endogenous ethanol, choline, and amino acids are altered and involved in the pathogenesis of MASLD (Figure 2).

Cassia obtusifolia L. (Fabaceae) seeds, a botanical drug with dual medicinal and dietary applications, contain bioactive metabolites including anthraquinones, naphthalenes, and naphthalopyranones, which exhibit hepatoprotective, hypolipidemic, and hypoglycemic properties (Chen et al., 2023). Among these metabolites, aurantio-obtusin (AO) and rubrofusarin-6-β-gentiobioside (RG) are representative anthraquinone and naphthalopyranone derivatives. Chronic oral administration of AO (20 mg/kg/day for 16 weeks) in HFD-induced murine model restored intestinal barrier integrity and remodeled gut microbiota composition, notably reducing the Firmicutes/Bacteroidetes ratio while enriching beneficial taxa such as Desulfovibrio (genus), Lachnoclostridium (genus), unclassified_f__Muribaculaceae (genus), and Lachnospiraceae_NK4A136_group (genus). These microbial shifts correlated with enhanced SCFA production, improved hepatic lipid metabolism, and attenuated inflammation. AO further ameliorated hepatic steatosis by modulating PPAR signaling pathways and downregulating lipogenesis-associated genes (Li et al., 2025). In contrast, Cassiae Semen extract (CSE), a standardized hydroalcoholic extract of Cassia obtusifolia seeds, demonstrated broader therapeutic efficacy. CSE treatment significantly increased the abundance of commensal bacteria (Dehalobacterium, Oscillospira, Ruminococcus) while suppressing pathobionts (Proteobacteria, Enterobacteriaceae, Erwinia), effects linked to intestinal mucosal repair, reduced endotoxin levels, and diminished hepatic inflammation. FMT from CSE-treated mice into HFD-fed recipients replicated these benefits, restoring microbial diversity, enhancing barrier function, and mitigating metabolic and inflammatory liver injury (Luo et al., 2021). These findings demonstrate that the hepatoprotective effects of CSE are directly linked to its microbiota-modulating properties, providing direct evidence for the “microbiota-host” interaction mechanism.

Compared to the single metabolite AO, CSE exhibits broader regulatory capacity over gut microbiota, such as suppressing pathogenic taxa (e.g., Proteobacteria, Erwinia), highlighting the advantage of multi-component synergistic intervention. This aligns with the characteristic “multi-metabolite, multi-target” therapeutic strategy of TCM polyherbal formulations. However, several limitations should be noted. First, the specific molecular targets of AO in regulating PPAR signaling pathways (e.g., PPARα/γ/δ isoforms) and its potential epigenetic regulatory mechanisms remain unelucidated. Second, the contributions of other bioactive metabolites in CSE—beyond AO and RG—to microbiota modulation have not been individually dissected, making it challenging to distinguish the effects of single metabolites from those of the whole extract.

Berberine (BBR), a bioactive isoquinoline alkaloid, is primarily isolated from botanical drugs including Coptis chinensis Franch. (Ranunculaceae), Phellodendron chinense C.K.Schneid. (Rutaceae), Hydrastis canadensis L. (Ranunculaceae), and Berberis aquifolium Pursh. (Berberidaceae). Preclinical studies have established its capacity to ameliorate MASLD through direct modulation of hepatic lipid metabolism (Yan et al., 2015). Mechanistic investigations by Shu et al. (Shu et al., 2021) further revealed that oral administration of BBR (100 mg/kg/day for 4 weeks) in HFD-fed C57BL/6J mice restored gut microbial homeostasis via selective enrichment of Clostridiales (order) and Lactobacillaceae (family), accompanied by expansion of Bacteroidales (order). These taxonomic shifts correlated with enhanced bile salt hydrolase (BSH) activity, facilitating the bioconversion of primary BAs to secondary forms such as deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA). Functionally, DCA and UDCA act as agonists of the FXR, activating intestinal FXR signaling to upregulate FGF15 expression. This cascade ultimately attenuates hepatic steatosis and inflammation by suppressing de novo lipogenesis and NF-κB-mediated proinflammatory cytokine release (Wang G. et al., 2019; Zaufel et al., 2021).

By demonstrating that BBR-induced BA conversion directly activates intestinal FXR signaling, these study bridge microbial metabolic output (secondary BAs) to host pathophysiology, offering a mechanistic framework for microbiota-host crosstalk in MASLD. However, the specific contributions of Clostridiales versus Lactobacillaceae to BSH activity and BA bioconversion remain unresolved. Functional validation (e.g., BSH gene knockout strains) is needed to confirm taxonomic causality. While FXR activation is implicated, the roles of FXR isoforms (FXRα/β) are unaddressed.

Puerarin, a bioactive isoflavone glycoside, is the principal metabolite derived from the roots of Pueraria lobata (Willd.) Ohwi (Fabaceae), a botanical drug traditionally used for its anti-inflammatory, antioxidant, and insulin-sensitizing properties (Zhou et al., 2014). Preclinical studies demonstrate its therapeutic potential in MASLD, with evidence highlighting its capacity to attenuate hepatic lipid accumulation, oxidative stress, and immune dysregulation (Xu et al., 2021; Zhou et al., 2022). In a methionine-choline-deficient (MCD) diet-induced murine model of MASH, oral administration of puerarin (200 mg/kg/day for 4 weeks) selectively suppressed the abundance of LPS-producing Helicobacter (genus) while enriching butyrate-generating Roseburia (genus), thereby ameliorating hepatic inflammation and steatosis (Gong et al., 2021). Butyrate, a SCFA critical for intestinal barrier integrity, mitigates endotoxemia by enhancing tight junction protein expression and suppressing NF-κB-driven proinflammatory cascades (Chen and Vitetta, 2020). Puerarin maintains gut homeostasis and the integrity of the intestinal mucosal barrier by enriching for the SCFA-producing bacteria Lactobacillus, Bifidobacterium and Turicibacter. In addition, these microbial shifts correlate with improved hepatic steatosis and lipid profiles (Yang et al., 2022).

These studies demonstrate that puerarin selectively suppresses the abundance of LPS-producing Helicobacter (genus) while enriching butyrate-generating Roseburia (genus). These microbial shifts are directly linked to butyrate-mediated intestinal barrier repair—evidenced by upregulated tight junction proteins—and inhibition of NF-κB-driven inflammatory signaling, thereby providing novel evidence for the “microbiota-host” interaction mechanism of isoflavonoids. However, the causal relationship between butyrate-induced NF-κB suppression and barrier restoration remains unelucidated, necessitating further validation through targeted metabolomics or functional assays using butyrate receptor antagonists (e.g., GPR109A).

MDG-1, a water-soluble inulin-type β-D-fructan isolated from Ophiopogon japonicus (Thunb.) Ker Gawl. (Asparagaceae), demonstrates multifaceted therapeutic potential in MASLD. Previous studies established its capacity to ameliorate hepatic lipid accumulation, steatosis, and insulin resistance through PPAR signaling modulation (Wang et al., 2017). Further investigations revealed that MDG-1 alleviates HFD-induced metabolic disorders by normalizing BA metabolic pathways, particularly through FXR-mediated regulation of hepatic CYP7A1 and intestinal FGF15 expression (Shi et al., 2016). Notably, MDG-1 exerts systemic metabolic benefits via gut microbiota remodeling. Chronic administration of MDG-1 (8% w/w dietary supplementation for 8 weeks) in HFD-fed C57BL/6J mice restored microbial equilibrium, selectively enriching SCFA-producing taxa such as Butyricimonas (genus) and Roseburia (genus), while elevating fecal concentrations of acetic acid and valeric acid (Wang X. et al., 2019). These microbial shifts correlated with AMPK pathway activation, evidenced by upregulated AMPK, SREBP-1c, and ACC-1, ultimately rebalancing hepatic lipid synthesis and oxidation (Si et al., 2018). This suggests that MDG-1 may exert anti-MASLD effects by promoting the production of SCFA, which in turn activates the AMPK signaling pathway in the liver. However, the causal relationship between MDG-1-induced enrichment of Butyricimonas/Roseburia and AMPK pathway activation remains unelucidated. Functional validation through germ-free animal models or genetic knockout experiments targeting SCFA receptors (e.g., GPR43, GPR109A) is required to confirm the direct regulatory effects of microbial metabolites (e.g., acetate, valerate) on host signaling pathways.

Dendrobium officinale Kimura et Migo (Orchidaceae), a revered botanical drug in traditional medicine, contains bioactive metabolites including polysaccharides, phenanthrenes, and bibenzyls, which collectively exhibit hypolipidemic, hypoglycemic, hepatoprotective, and microbiota-modulating properties (Yang et al., 2020; Fang et al., 2022a). Mechanistic studies demonstrate its efficacy in countering lipid metabolic dysregulation. Polysaccharides isolated from Dendrobium officinale attenuate HFD-induced hepatic lipid deposition by ameliorating insulin resistance through PPAR-γ activation (Qu et al., 2021). Concurrently, standardized D. officinale extracts reduce oxidative stress and inflammatory cascades via inhibition of the NF-κB/IκB signaling axis, thereby mitigating hepatocyte injury (Zhou et al., 2025). Furthermore, D. officinale polysaccharides (250–1,000 mg/kg/day orally for 10 weeks) reshape gut microbiota composition in HFD-induced MASH rats, specifically suppressing intestinal barrier-disrupting taxa and LPS-producing bacteria. This microbiota remodeling prevents LPS translocation to the liver and inhibits TLR4/NF-κB pathway activation, resulting in attenuated hepatic inflammation and steatosis (Tian et al., 2023).

Despite significant advancements, critical limitations persist in current research: The specific molecular targets through which D. officinale polysaccharides regulate PPAR-γ or TLR4/NF-κB pathways—including receptor isoforms (e.g., PPAR-γ1/γ2) or epigenetic modifications (e.g., DNA methylation, histone acetylation)—remain unelucidated. Advanced techniques such as CRISPR-Cas9 knockout models or single-cell RNA sequencing are required to dissect these mechanisms. The chemical profile of D. officinale extracts—including polysaccharide molecular weight distribution and quantitative analysis of bibenzyls—fails to meet ConPhyMP guidelines for natural product quality control. Furthermore, synergistic effects between polysaccharides and other bioactive metabolites (e.g., phenanthrenes) remain unassessed, potentially underestimating the holistic therapeutic efficacy of the whole botanical drug.

Astragalus membranaceus Fisch. ex Bunge (Fabaceae), a cornerstone botanical drug in TCM, produces bioactive metabolites including astragaloside IV (AS-IV) and Astragalus polysaccharides (APS), which exhibit hypoglycemic, hypolipidemic, and immunomodulatory properties (Fu et al., 2014). APS ameliorates HFD-induced metabolic dysfunction by remodeling gut microbiota composition and function (Hong et al., 2020). Specifically, APS administration (8% w/w dietary supplementation for 13 weeks) regulated serum and liver BA profiles in HFD-fed mice, especially increased serum taurohyodeoxycholic acid (THDCA) levels—a BA species associated with improved hepatic lipid deposition and glucose homeostasis (Zheng et al., 2024). However, the precise mechanism by which APS upregulates THDCA and its direct anti-steatotic effects remain uncharacterized, necessitating targeted metabolomic and receptor antagonist studies.

Further investigations revealed that APS alleviates MASLD in rats by rebalancing gut microbiota homeostasis, which in turn suppresses serum proinflammatory cytokines (e.g., TNF-α, IL-6) and activates the AMPK-PPAR-α signaling axis to inhibit de novo lipogenesis (Zhong et al., 2022). Parallel studies on AS-IV, a cycloartane-type triterpene glycoside, demonstrate its dual regulatory capacity: (1) suppression of TLR4/MyD88/NF-κB signaling, leading to downregulation of hepatic TNF-α, IL-6, and IL-8 in MASLD rats (Liu et al., 2020); (2) modulation of the FXR signaling pathway via gut microbiota-mediated BA metabolism. AS-IV reduces BSH activity, increasing intestinal tauro-β-muricholic acid (TβMCA), a potent FXR antagonist. This inhibits intestinal FXR-FGF15 signaling while activating hepatic FXR-SHP, collectively suppressing lipogenesis (Zhai et al., 2022). Notably, while TβMCA is murine-specific, its human analog glycoursodeoxycholic acid (GUDCA) shares similar FXR-modulating effects (Sun et al., 2018), underscoring the need for clinical trials to validate AS-IV’s translatability.

Emerging botanical drugs and their metabolites, though less extensively studied, demonstrate promising therapeutic potential for MASLD. Below, we critically evaluate their mechanisms of action through gut microbiota modulation.

Schisantherin A from Schisandra chinensis (Turcz.) Baill. (Schisandraceae): The lignan schisantherin A (80 mg/kg/day orally for 6 weeks) ameliorates hepatic steatosis in HFD-fed mice by restoring gut microbial diversity, particularly reducing the Firmicutes/Bacteroidetes ratio. This remodeling enhances intestinal barrier integrity (upregulated occludin) and reduces serum LPS levels, thereby inhibiting hepatic TLR4/NF-κB signaling and attenuating inflammation (Yu et al., 2022). However, the direct molecular targets linking schisantherin A to TLR4 pathway suppression (e.g., MyD88 phosphorylation or IRF3 activation) remain uncharacterized.

Caffeic Acid Phenethyl Ester (CAPE) from Chinese Propolis (Populus spp.): CAPE (75 mg/kg/day, 8 weeks), a major phenolic compound in Chinese propolis (15–29 mg/g) (Lv et al., 2021), mitigates HFD-induced MASLD by dual mechanisms: (1) inhibiting BSH activity, thereby increasing intestinal TCA and TDCA, which antagonizes FXR signaling; (2) reducing ceramide synthesis and enhancing GLP-1 secretion, collectively improving hepatic lipid metabolism (Zhong et al., 2023). Despite these insights, CAPE’s specificity for BSH inhibition (e.g., Bacteroides vs. Clostridium BSH isoforms) and its dose-dependent effects on FXR remain unaddressed.

Resveratrol from Vitis vinifera L. (Vitaceae): Resveratrol is a natural polyphenol that has been shown to be effective in improving liver inflammation and steatosis (Faghihzadeh et al., 2014; Faghihzadeh et al., 2015). Resveratrol (100 mg/kg/day, 12 weeks) attenuates MASLD progression via cannabinoid receptor modulation: inhibiting colonic CB1 receptors to preserve barrier function and activating CB2 receptors to suppress macrophage-driven inflammation (Chen M. et al., 2020). While effective in rodent models, its low oral bioavailability (<5%) and rapid phase II metabolism limit clinical utility. Nanoencapsulation strategies (e.g., chitosan-coated nanoparticles) may enhance its pharmacokinetic profile.

Tectorigenin (Tg) from Belamcanda chinensis (L.) Redouté (Iridaceae): Tg (25–50 mg/kg/day, 6 weeks), an isoflavone abundant in Belamcanda rhizomes, reshapes gut microbiota by promoting Akkermansiaceae (genus) and Verrucomicrobia (genus), which correlate with reduced hepatic TLR4/NF-κB activation and LPS-induced inflammation. Concurrently, Tg activates hepatic FXR and intestinal CYP7A1, accelerating BA synthesis and fecal excretion, thereby reducing lipotoxicity (Duan et al., 2022). However, the interplay between Tg-induced BA flux and microbiota remodeling requires validation using FXR knockout models.

In summary, preclinical studies highlight the therapeutic potential of botanical metabolites in MASLD through multi-target modulation of gut microbiota, including enrichment of SCFA-producing taxa, suppression of endotoxin-generating pathogens, and restoration of intestinal barrier integrity. These effects correlate with improved hepatic lipid metabolism and inflammation via pathways such as FXR/TLR4 signaling and AMPK activation. However, key limitations impede clinical translation. Firstly, overreliance on animal models with insufficient validation of bioavailability and in vitro efficacy. Secondly, incomplete elucidation of causal microbiota-host interactions and mechanistic signaling networks. Thirdly, lack of standardized phytochemical characterization and safety profiling for complex botanical drugs. Future research should prioritize translational strategies, including large-scale clinical trials with histological endpoints, advanced multi-omics integration to dissect metabolite-microbiota crosstalk, and nanotechnology-based delivery systems to enhance bioavailability. Additionally, mechanistic studies using germ-free models or receptor-specific knockouts are warranted to validate therapeutic targets and optimize botanical formulations for clinical application.

Zuogui-Jiangtang-Qinggan-Fang (ZGJTQGF), a decoction comprising ten botanical drugs including A. membranaceus Fisch. ex Bunge (Fabaceae), C. chinensis Franch. (Ranunculaceae), and P. lobata (Willd.) Ohwi (Fabaceae), demonstrates multi-target efficacy against MASLD. In HFD-induced C57BL/6J mice, oral administration of ZGJTQGF (15 g/kg for 8 weeks) attenuated hepatic steatosis by restoring lipid homeostasis and enhancing intestinal barrier integrity, as evidenced by upregulated tight junction proteins (ZO-1, occludin, and claudin-1). Gut microbiota analysis revealed significant enrichment of SCFA-producing taxa, including Lactobacillaceae (family), Lactobacillus (genus), Akkermansia (genus), and Bacteroidota (phylum), accompanied by elevated fecal acetate and butyrate concentrations (Zou et al., 2023). The synergistic effects of ZGJTQGF’s multi-component composition—such as berberine from C. chinensis (FXR activation) and puerarin from P. lobata (NF-κB inhibition)—highlight its “multi-metabolite, multi-pathway” therapeutic strategy. However, critical gaps persist: Firstly, the necessity of microbiota remodeling for ZGJTQGF’s efficacy remains unproven, requiring validation via FMT or germ-free models. Secondly, batch-to-batch variability in the decoction’s chemical profile (e.g., alkaloid/polysaccharide ratios) lacks standardization per ConPhyMP guidelines.

Zexie-Baizhu Decoction (AA), a Chinese classical formulation composed of Alisma orientalis (Sam.) Juzep. (Alismataceae) and Atractylodes macrocephala Koidz (Asteraceae) in a 5:2 ratio, has a long history of use in treating metabolic disorders. Multi-omics analysis showed that AA was able to regulate energy sensors, inhibit adipogenesis and alleviate lipid metabolism disorders (Cao Y. et al., 2022). In MASLD mice, AA administration (1.5 g/kg/day orally for 24 weeks) significantly ameliorated HFD-induced liver injury. Further analysis revealed that AA inhibited hepatic lipid deposition by regulating gut microbiota and its metabolites SCFA and BA, highlighting the potential of AA in regulating lipid metabolism (Shi et al., 2025). These findings provide new perspectives on the anti-MASLD effects of AA and deserve more in-depth studies to elucidate its specific mechanism.

Qushi Huayu Formula (QSHY), a polyherbal preparation containing Artemisia capillaris Thunb. (Asteraceae), Reynoutria japonica Houtt. (Polygonaceae), Hypericum japonicum Thunb. ex Murray (Hypericaceae), Curcuma longa L. (Zingiberaceae), and Gardenia jasminoides Ellis. (Rubiaceae), demonstrates efficacy in improving hepatic lipid metabolism in MASLD patients (Liu et al., 2024). In HFD-induced murine model, QSHY (0.93 g/kg/day orally for 4 weeks) activated hepatic AMPK, downregulated sterol regulatory element-binding protein 1 (SREBP-1) and carbohydrate-responsive element-binding protein (ChREBP) expression, and suppressed de novo lipogenesis (Feng et al., 2013). Gut microbiota profiling revealed QSHY’s capacity to enrich Parabacteroides (genus). Additionally, QSHY inhibited colonic MAPK signaling, preserving tight junction integrity (ZO-1, occludin) and attenuating endotoxin translocation (Leng et al., 2020). However, the causal link between MAPK inhibition and microbiota remodeling requires validation via FMT studies.

Shenling Baizhu Powder (SLBZP), a spleen-invigorating formulation from the Song Dynasty’s Taiping Huimin Hejiju Fang, comprises 10 botanical drugs, including Panax ginseng C.A.Mey. (Araliaceae) and Dioscorea polystachya Turcz. (Dioscoreaceae). SLBZP (30 g/kg/day orally for 16 weeks) enhances gut microbiota-derived SCFAs by enriching Bifidobacterium (genus) and Anaerostipes (genus), which activate the UCP2/AMPK/IF1 signaling axis to boost hepatic mitochondrial ATP synthesis (Zhang et al., 2018; Yao et al., 2023). Parallel studies demonstrated that SLBZP reduces intestinal LPS translocation by suppressing TLR4/NLRP3 inflammasome activation, thereby downregulating hepatic pro-inflammatory factor expression (Pan et al., 2021). Nevertheless, the upstream regulators connecting TLR4 signaling to NLRP3 activation (e.g., MyD88/TRIF adaptors) remain uncharacterized.

Zhishi Daozhi Decoction (ZDD), a classical formulation comprising eight botanical drugs such as Citrus aurantium L. (Rutaceae), Rheum palmatum L. (Polygonaceae), C. chinensis Franch. (Ranunculaceae), and Scutellaria baicalensis Georgi (Lamiaceae), demonstrates therapeutic potential in MASLD. Preclinical studies in HFD-fed mice revealed that ZDD (14.5 g/kg/day orally for 4 weeks) modulates gut microbiota composition by decreasing Firmicutes/Bacteroidetes ratio, while enhancing intestinal barrier integrity via upregulation of occludin and ZO-1 (Bi et al., 2022). These changes correlated with reduced hepatic triglyceride content. However, the absence of FMT to validate causality and the lack of mechanistic details (e.g., specific microbial taxa or signaling pathways involved) limit the interpretability of these findings. Future studies should employ metagenomic sequencing and targeted metabolite profiling to dissect ZDD’s microbiota-dependent effects.

Si Miao Formula (SMF), a polyherbal preparation containing P. chinense C.K.Schneid. (Rutaceae) bark, Atractylodes lancea (Thunb.) DC. (Asteraceae) rhizome, Coix lacryma-jobi L. (Poaceae) seeds, and Achyranthes bidentata Blume (Amaranthaceae) roots, exhibits therapeutic effects on hyperuricemia and MASLD (Lin et al., 2020). Recent studies have found that SMF has the potential to ameliorate insulin resistance and inhibit adipogenesis (Jiang et al., 2022). In high fat/high sucrose diet-fed mice, SMF (10–20 g/kg for 16 weeks) ameliorated insulin resistance and hepatic lipid deposition by modulating gut microbiota (e.g., enriching Akkermansia [genus]). SMF suppressed hepatic de novo lipogenesis via FXR/SREBP-1c signaling inhibition, downregulating key lipogenic genes (Acly, Fas, Acc, and Scd-1) and pro-inflammatory cytokines (Han et al., 2021; Chen et al., 2022). Despite these benefits, the formulation’s batch-to-batch variability (e.g., alkaloid content from P. chinense) and the absence of clinical validation necessitate further standardization and human trials.

Lingguizhugan Decoction (LGZG), a four-herb formulation including Poria cocos (Schw.) Wolf (Polyporaceae), Cinnamomum cassia (L.) J. Presl (Lauraceae), A. macrocephala Koidz. (Asteraceae), and Glycyrrhiza uralensis Fisch. ex DC. (Fabaceae), improves insulin sensitivity and hepatic steatosis in MASLD (Dai et al., 2022). In HFD-induced MASH mice, LGZG (2.5–10 g/kg/day orally for 4 weeks) reshaped gut microbiota by increasing Bacteroides (genus) and Akkermansia (genus), while reducing tauro-α/β-muricholic acid (Tα/βMCA) levels and elevating deoxycholic acid (DCA). This BA profile activated hepatic FXR/TGR5 signaling, attenuating lipid accumulation (Wang J. et al., 2024). LGZG also inhibited the STING-TBK1-NF-κB pathway in Kupffer cells, mitigating LPS-induced oxidative stress and inflammation (Cao L. et al., 2022). Nevertheless, the interplay between microbiota remodeling and STING pathway suppression remains unelucidated, requiring co-culture models or single-cell transcriptomics for validation.

Chaihu Guizhi Ganjiang Decoction (CGGD), derived from Treatise on Febrile Diseases, contains seven botanical drugs, including Bupleurum chinense DC. (Apiaceae), C. cassia (L.). J.Presl (Lauraceae), and S. baicalensis Georgi (Lamiaceae). Numerous studies have shown that the metabolites of CGGD have various effects such as anti-inflammatory, antifibrotic and improved liver function (Ahn et al., 2021; Li X. et al., 2021). In MCD-induced MASH rats, CGGD (5.1–20.4 g/kg/day orally for 6 weeks) reduced pro-inflammatory taxa and preserved intestinal barrier function, thereby lowering hepatic LPS levels and TLR4/MyD88/NF-κB activation (Wu et al., 2024). Concurrently, CGGD enhanced PPARα-mediated fatty acid oxidation. While promising, the lack of chemical standardization (e.g., saikosaponin content from B. chinense) and clinical data limits its translational potential.

Salvia-Nelumbinis Naturalis (SNN) is a polyherbal formulation comprised of four botanical drugs, including Salvia miltiorrhiza Bge. (Lamiaceae), Semen Nelumbinis, R. japonica Houtt. (Polygonaceae), A. capillaris Thunb. (Asteraceae) (Ma et al., 2017). SNN (750 mg/kg/day orally for 4 weeks) attenuated LPS-induced intestinal barrier dysfunction by activating colonic FXR-FGF15 signaling and normalizing fecal BA profiles (Li C. et al., 2021). Qingrequzhuo capsule (QRQZ) improved hepatic inflammatory and lipid metabolism in MASH mice mainly by modulating gut microbiota and intestinal mucosal barrier, which in turn inhibits the TLR4/NF-κB pathway though its chemical composition remains uncharacterized (Lv et al., 2022). Yindanxinnaotong reduced hepatic lipid deposition via AMPK-mediated fatty acid oxidation, yet its multi-omics data lack functional validation (Huang et al., 2024).

In conclusion, polyherbal formulations demonstrate significant therapeutic potential for MASLD through microbiota-centric mechanisms. However, current studies on polyherbal formulations for MASLD exhibit the following shared limitations: Firstly, polyherbal formulations comprise chemically complex mixtures of botanical metabolites that interact with multiple host-microbiota targets. Current studies often fail to distinguish the contributions of individual components or validate causality via functional assays (e.g., FMT, germ-free models). Secondly, batch-to-batch variability in bioactive constituents (e.g., alkaloid content in SMF, saikosaponins in CGGD) undermining reproducibility. To address these gaps, future research must prioritize integrate multi-omics (metagenomics, metabolomics) with in vitro systems (gut-liver organoids) to deconvolute metabolite-microbiota-host interactions. Besides, establish standardized protocols for extract preparation (e.g., HPLC fingerprinting of ZGJTQGF’s berberine/puerarin ratios) and pharmacodynamic evaluation aligned with pharmacopeial standards.