Abstract: Objective:This work was designed to explore the protective effect of heartleaf houttuynia herb essential oil against doxorubicin (DOX) -induced myocardial injury in rats. Methods:In this work, heartleaf houttuynia herb essential oil was prepared by steam distillation, and its components were determined by gas chromatography-mass spectrometry (GC-MS). Subsequently, DPPH radical scavenging capacity, reducing power and chelating ability of metal ions were employed to evaluate its antioxidant activities. Furthermore, the myocardial injury model was established by intraperitoneal injection of DOX, which was divided into control group, DOX model group, 25, 50 and 100 mg/kg body dose of essential oil of heartleaf houttuynia herb groups and vitamin E (VE) 500 mg/kg body group. Whole blood was collected for blood routine detection. Myocardial tissue was used for hematoxylin-eosin staining (HE) analysis. Moreover, malondialdehyde contents (MDA) in myocardial tissue, the activity of lactate dehydrogenase (LDH) in serum and catalase (CAT) in myocardial tissue were detected by the commercial kits. In addition, the content of short-chain fatty acids was determined by agilent 7890B gas chromatograph. Results:GC-MS data showed that the heartleaf houttuynia herb essential oil mainly contained 28 chemical components. Antioxidant activities in vitro tests further showed that the essential oil had potent antioxidant capacity. In three groups of heartleaf houttuynia herb essential oil and V_E group, there were no significant changes in body weight and blood routine, when compared to DOX group. However, compared with the DOX model group, heartleaf houttuynia herb essential oil significantly increased CAT in myocardial tissue, while decreased MDA contents in myocardial tissue and LDH release in serum. HE dyeing analysis suggested that the essential oil could inhibit the morphological changes of myocardial tissue. At the same time, data showed that treatment with DOX alone remarkably decreased the short-chain fatty acid content, but there was no significant changes after administration of heartleaf houttuynia herb essential oil in rat. Conclusion:Heartleaf houttuynia herb essential oil possessed protective effects against DOX-induced myocardial injury by attenuating oxidative stress.