BACKGROUND:A network-based pharmacological approach has identified multifunctional effects of the main bioactive compounds in the Trichosanthis Fructus-Allii Macrostemonis Bulbus on coronary heart disease;however,the mechanism of its therapeutic effect on coronary heart disease has not been fully elucidated. OBJECTIVE:To investigate the role and mechanism of Trichosanthis Fructus-Allii Macrostemonis Bulbus in improving coronary heart disease by regulating the composition of gut microbiota. METHODS:Forty Sprague-Dawley rats were randomly divided into four groups:blank control group(n=10),model group(n=10),positive drug group(n=10),and medicine pair group(n=10).A rat model of coronary heart disease was established by continuous gastric perfusion of fat emulsion and injection of pituitrin.After modeling,rats in the model group were gavaged with distilled water(10 mL/kg)for control,rats in the positive drug group were gavaged with simvastatin 4 mg/kg per day,and rats in the medicine pair group were gavaged with Trichosanthis Fructus-Allii Macrostemonis Bulbus pairs 7.56 g/kg per day.All interventions lasted for 14 days.Electrocardiograms and myocardial pathology were observed,and blood lipid levels were measured.The structure of gut microbiota was analyzed using 16S rDNA sequencing technology. RESULTS AND CONCLUSION:Electrocardiogram results showed ST segment elevation in the model group.There were no significant abnormalities in the electrocardiograms of the positive drug group and medicine pair group.Compared with the blank control group,the levels of total cholesterol,triacylglycerol,and low-density lipoprotein cholesterol were significantly higher in the model group(P<0.05).Compared with the model group,the levels of total cholesterol,triacylglycerol,and low-density lipoprotein cholesterol were significantly lower in the positive drug group and medicine pair group(P<0.05).Compared with the blank control group,focal myocardial cell necrosis was observed in the model group,while partial myocardial cell disarray was observed in the positive drug group and medicine pair group.Compared with the blank control group,the Ace,Shannon,and Chao indices were increased(P<0.05)and the Simpson index was decreased(P<0.05)in the model group,positive drug group and medicine pair group.Compared with the model group,the Ace and Chao indices were decreased(P<0.05),while the Shannon index showed no significant difference(P>0.05)and the Simpson index was also decreased(P<0.05)in the positive drug group and medicine pair group.Compared with the blank control group,the relative abundances of Desulfovibrionia,Muribaculaceae_norank,etc.were increased in the model group,while those of Clostridia,[Eubacterium]_coprostanoligenes_group_norank,etc.were decreased.Compared with the model group,the relative abundances of WPS-2_norank,Muribaculaceae_norank,etc.were increased in the medicine pair group,while those of Clostridia,[Eubacterium]_coprostanoligenes_group_norank,etc.were decreased;the relative abundances of Desulfobacterota,[Eubacterium]_coprostanoligenes_group_norank,etc.were increased in the positive drug group,while those of Firmicutes,Muribaculaceae_norank,etc.were decreased.Compared with the positive drug group,the relative abundances of Desulfobacterota,Bacteroides,etc.were increased in the medicine pair group,while those of Firmicutes,[Eubacterium]_coprostanoligenes_group_norank,etc.were decreased.The LEfSe results showed that the medicine pair group had the highest microbial enrichment,followed by the blank control group and positive drug group,with the model group having the lowest microbial enrichment.To conclude,Trichosanthis Fructus-Allii Macrostemonis Bulbus pairs can improve the development of coronary heart disease by regulating gut microbiota composition,providing new insights for further research and development of Trichosanthis Fructus-Allii Macrostemonis Bulbus pairs.