Microcalorimetry combined with chemometics for antibacterial evaluation of Sophora alopecuroides on Staphylococcus aureus

This study aimed to evaluate the antibacterial activities of Sophora alopecuroides from various production regions of China on Staphylococcus aureus by microcalorimetry and chemometics. From the heat-flow power–time curves of S. aureus growth affected by the extracts of S. alopecuroides , some vital thermokinetic parameters, such as the growth rate constant ( k) , the maximum heat-production rate ( P m ), the appearance time ( t m ) and the total heat-production ( Q ), were obtained and were analyzed by principal component analysis and hierarchical cluster analysis. The results showed that all the S. alopecuroides samples expressed strong antibacterial activities to S. aureus , but the activities varied evidently on their production regions. The samples from Xinjiang (northwest region of China) showed the strongest antibacterial activities with inhibitory ratio ( I ) of 81.3%, while those from Inner Mongolia (North region of China) gave the contrast results with I of 9.2%. The findings indicated that the anti- S. aureus activities of S. alopecuroides had close relationship with the production regions. This study has provided a combined model of microcalorimetry and chemometrics to evaluate the antibacterial activities of medicinal herbs on bacteria.