Abstract

Background: Acalypha australis Linn. (A. australis) was a kind of traditional Chinese plant food with high nutrition and was usually used to treat diarrhoea and other bacterial diseases clinically in China. The purpose of this paper was to establish a rapid and effective approach for searching bioactive compounds from A. australis species.

Method: The chromatographic fingerprints were established using ultra-performance liquid chromatography/ mass spectrometry (UPLC/MS), and the antibacterial activities were also studied with agardiffusion and broth microdilution methods. Moreover, correlational analysis, stepwise regression and partial least-square regression were performed to explore the relationship between the compositions and bioactivities and to identify the active compounds from A. australis. All the characteristic peaks in the UPLC/MS fingerprint were separated with semi-preparative HPLC and subsequently confirmed with ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC-Q-TOF-MS).

Result: Apart from nicotinic acid, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, australisin, and quercetin, C₁₃H₈O₈, C₂₂H₁₂O₁₃ and C₂₇H₂₂O₁₈ were first found to be the main antibacterial components in A. australis. Among them, seven were identified by the “spectrum–effect relationship” strategy, while two minor active compounds were not conjectured in this study.

Conclusion: This work successfully provides a general model that combined the chromatographic fingerprint and bioactivity assay to study the spectrum–effect relationships, which could be used to discover the primary active ingredients in traditional Chinese plant food and herb medicines.

Keywords: Chinese herb medicines, Acalypha australis Linn., spectrum-effect relationships, bioactive compound, chromatographic fingerprints, antibacterial activity.

Graphical Abstract