Research report: Integrated chemical profiling and lipidomics reveal that Mailuoning oral liquid alleviates diet-induced MASLD via PPARα-mediated lipid homeostasis and COX-2 inhibition, with identification of potential active constituents

A traditional Chinese medicine formula that has been used clinically in China for over three decades has now been studied in rats for its effects on diet-induced fatty liver disease, with researchers reporting benefits via both PPARα activation and COX-2 inhibition. Mailuoning oral liquid, a standardized five-herb preparation originally derived from the classic prescription Simiao Yong’an Decoction, has now been shown in a comprehensive new study to combat diet-induced fatty liver disease through not one but two distinct molecular pathways simultaneously.

Over three decades, the global prevalence of MASLD has risen from 25.3 percent during the period 1990 to 2006 to 38.0 percent between 2016 and 2019, according to data cited in the study. According to data cited in the study, the worldwide prevalence of the condition has surged from 25.3 percent during the period 1990 to 2006 to 38.0 percent between 2016 and 2019. Despite this alarming trajectory, therapeutic options remain severely limited. Only one drug, resmetirom, marketed as Rezdiffra, has been approved for treating the more advanced inflammatory stage of the disease, leaving the vast majority of patients with earlier-stage disease without any licensed pharmacotherapy. This treatment gap has driven researchers to explore whether existing medicines and natural products might be repurposed to fill the void.

The research team, led by investigators at Shanghai University of Traditional Chinese Medicine, designed an ambitious multi-omics investigation to dissect exactly how Mailuoning works in the body. They fed male Sprague-Dawley rats a high-fat, high-fructose diet for sixteen weeks to induce early-stage MASLD, then administered the herbal formula at two different doses for an additional eight weeks. Using ultra-high-performance liquid chromatography coupled with Q-Exactive Orbitrap high-resolution mass spectrometry, the team profiled the chemical constituents of the formula and tracked which compounds actually reached the bloodstream and liver tissue of the treated animals.

The chemical analysis revealed staggering complexity. A total of 143 individual compounds were confidently identified in the formula, spanning organic acids, flavonoids, iridoids, triterpenoids, lignans, phenylpropanoids, and sterones. Of these, 48 compounds were detected as blood-entering components that reproducibly appeared in the serum of treated rats, while 92 compounds were identified as liver-entering components that accumulated in hepatic tissue. This bioavailability filtering step proved crucial, as it narrowed the focus from the enormous chemical diversity of the crude extract down to the specific molecules that actually reach the target organ in biologically relevant concentrations.

The results of the animal experiments were striking. Rats receiving the herbal formula showed significant reductions in serum total cholesterol, alanine aminotransferase, and aspartate aminotransferase levels compared to untreated controls on the high-fat, high-fructose diet. The higher dose significantly reduced elevated liver triglyceride and total cholesterol levels. Histological examination confirmed that the extensive lipid accumulation seen in the diseased livers was markedly alleviated by treatment. The formula also improved glucose metabolism, reducing insulin levels and improving insulin sensitivity, effects that were absent in rats receiving a preparation containing only the excipient vehicle without the herbal extracts.

Perhaps the most fascinating finding came from the lipidomics analysis, which revealed that the formula performs a kind of molecular juggling act on the hepatic lipidome. The diseased livers showed massive accumulation of triglycerides alongside depletion of structural phospholipids, particularly phosphatidylcholine and phosphatidylethanolamine species that maintain cell membrane integrity. Treatment reversed this pathological pattern in both directions simultaneously, reducing 142 upregulated lipids including 129 triglyceride species while restoring 25 depleted membrane phospholipids. Among the restored phospholipids were 11 species containing arachidonic acid acyl chains and 3 containing docosahexaenoic acid, the omega-3 fatty acid critical for membrane fluidity.

The mechanism underlying these effects centers on peroxisome proliferator-activated receptor alpha, or PPARα, a master nuclear receptor that regulates fatty acid oxidation and lipid turnover in the liver. The researchers demonstrated that the formula promoted PPARα nuclear translocation and upregulated its downstream target genes involved in fatty acid beta-oxidation. Going further, they screened the blood-exposed constituents for direct PPARα activating activity using cell-based assays and molecular docking. Seven compounds emerged as validated direct PPARα agonists: chlorogenic acid, macranthoidin B, luteoloside, harpagide, angoroside C, oleanolic acid, and betaine. These chemically diverse molecules, spanning phenolic acids, iridoid glycosides, and phenylethanoid glycosides, all activated PPARα transcriptional activity in reporter gene assays.

But the dual mechanism does not stop there. The study also uncovered a complementary anti-inflammatory axis involving cyclooxygenase-2, or COX-2, the same enzyme targeted by common anti-inflammatory drugs. In the diseased livers, levels of COX-2-derived prostaglandins PGE2 and PGD2 were significantly elevated, reflecting inflammatory activation. Treatment normalized these prostaglandin levels while preserving alternative metabolic pathways. Two specific compounds were identified as novel direct COX-2 inhibitors: the iridoid glycoside secologanoside, with a half-maximal inhibitory concentration of 14.61 nanomolar, and the triterpenoid saponin chikusetsusaponin IVa, with an IC50 of 120.9 nanomolar. For comparison, the positive control celecoxib showed an IC50 of 15.16 nanomolar in the same assay. Molecular dynamics simulations revealed that both compounds bind to an allosteric side pocket rather than the canonical catalytic site, modulating the flexibility of the catalytic pocket through a mechanism distinct from traditional competitive inhibitors.

Mailuoning was developed from the classic prescription Simiao Yong’an Decoction, originally recorded in the historical text Yan Fang Xin Bian, by removing two herbs and adding three others to enhance blood-activating and yin-nourishing effects. The current five-herb formula, composed of Achyranthis Bidentatae Radix, Scrophulariae Radix, Dendrobii Caulis, Lonicerae Japonicae Flos, and Lonicerae Flos in a fixed ratio, has been clinically used in China for over three decades for ischemic cerebrovascular and peripheral vascular diseases. A Cochrane systematic review of 21 randomized controlled trials involving 1,746 patients concluded that the formula is safe and improves neurological outcomes after acute ischemic stroke. This established clinical safety profile, combined with the new mechanistic data, strengthens the case for its potential repurposing in metabolic disorders.

The researchers acknowledge that their work has limitations and that further studies are needed before clinical application can be considered. The screening cascade may have overlooked compounds that lack direct lipid-lowering effects, and validation in models that progress to advanced steatohepatitis with fibrosis is still required. The individual and synergistic contributions of the identified agonists and inhibitors to the overall in vivo efficacy also warrant further pharmacokinetic-pharmacodynamic analysis. Nevertheless, the study represents a significant advance in the scientific understanding of how complex botanical formulations can act on multiple molecular targets simultaneously, bridging the gap between traditional ethnopharmacological knowledge and contemporary metabolic disease management through rigorous, reductionist pharmacology.

Subject of Research: Mechanistic study of Mailuoning oral liquid against diet-induced MASLD via PPARα activation and COX-2 inhibition

Article Title: Integrated chemical profiling and lipidomics reveal that Mailuoning oral liquid alleviates diet-induced MASLD via PPARα-mediated lipid homeostasis and COX-2 inhibition, with identification of potential active constituents

Article References: Wu, S., Jia, W., Zhou, X., Zhu, L., Wang, K., Li, J., Ji, L., Liu, W., & Xu, H. (2026). Integrated chemical profiling and lipidomics reveal that Mailuoning oral liquid alleviates diet-induced MASLD via PPARα-mediated lipid homeostasis and COX-2 inhibition, with identification of potential active constituents. Frontiers in Pharmacology, 17, Article 1939197. https://doi.org/10.3389/fphar.2026.1939197

Image Credits: AI Generated

DOI: 10.3389/fphar.2026.1939197

Keywords: MASLD, Mailuoning, PPARα, COX-2, lipidomics, traditional Chinese medicine, fatty liver disease, herbal formula, secologanoside, chikusetsusaponin IVa, drug repurposing, metabolic disease