Objective: To explore the antibacterial activity differences of various extracts of Coptidis Rhizoma from the perspective of biothermodynamics

and to provide a new idea and evidence for the study on active components of Coptidis Rhizoma. Method: Microcalorimetry was used to establish biothermodynamics of Escherichia coli (EC)

Staphylococcus aureus (SA) and Shigella dysenteriae (SD) on Luria-Bertani (LB) medium under the sterile conditions of 37℃ with an inoculum concentration of 1×105cell/mL. This method was used to plot growth thremogram curves of these three bacteria upon the treatments by aqueous extracts

alkaloids and non-alkaloid constituents of Coptidis Rhizoma. The differences in the growth metabolism of these bacteria upon various treatments were assayed on the basis of corresponding biothermodynamics parameters (mainly including growth rate constant (k)

growth inhibition ratio (I)

inhibition ratio in half of drug concentration (IC50)

maximum heat output (Pmax) and the time to reach Pmax(tmax). Result: The aqueous extracts and alkaloids significantly inhibited the growth of the three bacteria

and all the orders were alkaloids>aqueous extracts; non-alkaloid constituents had no significant inhibitory effects

and even had promotion effects to these three bacteria. The order of the antibacterial ability was SA> SD> EC for the same extraction part. Conclusion: In summary

the microcalorimetry analysis reveals that in Coptidis Rhizoma

the main active components are alkaloids that display the strongest antibacterial activities against SA.