To investigate the potential targets and pathways of eupalinolide B (EB) in doxorubicin (DOX)-induced dilated cardiomyopathy (DCM), and to verify EB inhibits cardiomyocyte apoptosis and inflammatory response by regulating the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway.

Database screening was used to identify the intersecting targets of EB and DCM, followed by functional and pathway enrichment analyses and molecular docking validation. A DCM mouse model was established. The successfully modeled mice were randomly divided into model group, experimental-L group (5 mg·kg^-1 EB), experimental-H group (20 mg·kg^-1 EB), positive control group (5 mg·kg^-1 positive drug captopril), inhibitor group (1 mg·kg^-1 p38 MAPK inhibitor SB203580) and activator group (20 mg·kg^-1 EB+0.10 mg·kg^-1 p38 MAPK activator anisomycin). In addition, normal and healthy mice were selected as the blank group. Each group had 10 mice. After the intervention, cardiac function was detected by echocardiography; serum and myocardial tissues were collected, serum inflammatory factors and myocardial injury markers were measured by enzyme-linked immunosorbent assay (ELISA); pathological damage, fibrosis and cell apoptosis of myocardial tissue were detected by hematoxylin and eosin (HE) staining, Masson staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining; the expression of apoptosis-related proteins, inflammatory factors, phosphorylation (p-)p38 MAPK and p38 MAPK in myocardial tissue was detected by immunohistochemistry and Western blot.

A total of 34 potential targets of EB and 1 018 DCM-specific targets were screened, and 5 potential targets of EB for DCM treatment were identified, involving the MAPK signaling pathway. The left ventricular fractional shortening (LVFS) values in blank group, model group, experimental-L group, experimental-H group, inhibitor group and activator group were (41.26±0.07)%, (26.60±0.72)%, (30.90±0.29)%, (44.26±1.73)%, (42.62±1.82)% and (33.66±2.74)%, respectively; the N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were (734.85±90.24), (1 509.28±163.17), (1 240.62±157.95), (841.57±88.06), (862.91±87.92) and (1 159.76±125.71) pg·mL^-1, respectively; the B-cell lymphoma-2 (Bcl-2) positive rates were (16.81±1.82)%, (3.02±0.54)%, (6.97±0.86)%, (14.29±1.43)%, (13.51±1.46)% and (8.14±0.95)%, respectively; the Bcl-2-associated X protein (Bax) positive rates were (1.59±0.18)%, (18.37±2.51)%, (12.42±1.63)%, (3.84±0.45)%, (4.09±0.41)% and (11.53±1.28)%, respectively; the relative expression levels of p-p38 MAPK/p38 MAPK were 0.23±0.03, 0.86±0.09, 0.64±0.08, 0.35±0.04, 0.38±0.05 and 0.61±0.08, respectively. Comparisons between model group and blank group, between experimental-L/-H groups or inhibitor group and model group, and between activator groups and experimental-H group, the above indicators all showed statistically significant differences (all P<0.05).

EB may alleviate the myocardial inflammatory response and cardiomyocyte apoptosis in DOX-induced cardiomyopathy mice and improve myocardial damage by inhibiting the phosphorylation of p38 MAPK.