Objective To investigate the therapeutic effect and mechanism of iridoid fraction from Morinda officinalis on aging-related sarcopenia. Methods Using monotropein and deacetylasperulosidic acid as analytical markers, effects of different ethanol concentrations on extraction efficiency of active iridoids fraction from M. officinalis via heated reflux extraction was investigated. The extract was concentrated under reduced pressure and subsequently enriched and purified using macroporous adsorption resin to obtain the total active iridoid fraction. By comparing the elution efficiencies of solvents with varying polarities, purification parameters were optimized. Following the establishment and validation of a high performance liquid chromatography (HPLC) analytical method, the content of major iridoid components in active fraction was quantified. The purified fraction was then used for subsequent pharmacodynamic evaluations. The C2C12 cell differentiation model and a D-galactose (D-gal)-induced C2C12 myotube atrophy model were employed to assess the effects of iridoid fraction on promoting myotube differentiation and ameliorating myotube atrophy, with MYHC protein expression serving as the indicator. A D-gal-induced accelerated aging mouse model was utilized to evaluate the therapeutic effects of iridoid fraction through grip strength tests, hindlimb muscle mass measurements, and hematoxylin-eosin (HE) staining of tibialis anterior and gastrocnemius muscles. Differentially expressed genes in gastrocnemius muscle of mice in each group was analyzed by transcriptome sequencing, and the results were further verified by Western blotting and qRT-PCR for the expression changes of related differentially expressed genes indicated by transcriptome sequencing, in combination with network pharmacology analysis. Results The extraction of iridoid components from M. officinalis was optimized using a 60% ethanol solution under heated reflux conditions, resulting in the highest iridoid content. In the purification process, H103 macroporous adsorption resin demonstrated superior adsorption performance, with water as the eluent resulting in the highest elution rate of target constituents. The iridoid fraction from M. officinalis significantly ameliorated D-gal-induced atrophy in C2C12 myotubes (P < 0.001), and promoted myotube differentiation (P < 0.05, 0.01, 0.001). The iridoid fraction could significantly enhance the limb pulling force and ratio of hind limb muscle mass to body mass of accelerated aging mice (P < 0.05, 0.01, 0.001), significantly increase the cross-sectional area of the tibialis anterior muscle and gastrocnemius muscle in aging mice (P < 0.01, 0.001), thereby improving the phenotype of age-related sarcopenia. Further mechanism studies revealed that iridoid fraction could up-regulate the expression levels of key proteins in phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway (P < 0.05, 0.01, 0.001), and significantly up-regulate the expression levels of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), serine/threonine kinase 1 (AKT1) and mTOR genes (P < 0.05, 0.01, 0.001). And PI3K inhibitor LY294002 significantly inhibited the upregulation of PI3K/Akt/mTOR signaling pathway related protein expressions by iridoid fraction (P < 0.05). Conclusion The iridoid fraction of M. officinalis can significantly improve sarcopenia caused by aging, and its mechanism is related to the regulation of PI3K/Akt/mTOR signaling pathway.

sarcopenia  /  Morinda officinalis How  /  iridoids  /  aging  /  PI3K/Akt/mTOR signaling pathway  /  monotropein  /  deacetylasperulosidic acid