A strategy for evaluating antipyretic efficacy of Chinese herbal medicines based on UV spectra fingerprints

Ethnopharmacological relevance Quality analysis and control of Chinese herbal medicines (CHM) or herbal medicines (HM) are being more and more investigated based on fingerprint analysis, and there are also some researches on correlating fingerprints of CHM to their efficacy. Multi-component analysis methods together with fingerprints are considered potential useful tools to select candidate herbal drugs from extracts of herbs in pharmacological/bio-prospecting investigations. Aim of the study To explore a strategy for evaluating efficacy strength of CHM samples based on their spectra fingerprints and validate it. Methodology Radix bupleuri (RB), a typical Chinese medicinal herb for relieving exterior syndrome, and Flos lonicerae (FL), Fructus forsythiae (FF), and Radix isatidis (RI) that are widely applied Chinese herbs for heat clearing and detoxifying, were selected as herbal sources. The aqueous extracts, volatile oils and mixtures of the extracts and oils of the four herbs, plus Ibuprofen suspension (IS), Shuanghuanglian oral liquid (SHL), mixture of SHL and the volatile oils of FL and FF, were used for subject samples to do antipyretic experiments on rats. Ultraviolet spectra were used as the spectra fingerprints to represent chemical characteristics of the samples. Principal component analysis (PCA) and canonical correlation analysis (CCA) were adopted as evaluation tools to establish the correlation between pharmacological and spectra data, from which a spectral index for evaluating antipyretic effects of CHM samples was constructed. Furthermore, four compound samples were designed by mixing 50% volatile oils and 50% aqueous extracts of the four herbs with different ratios to validate the strategy. Results Efficacy sequence of the 15 calibrating and 4 validating CHM samples, defined by the first canonical correlative variable U1 of their UV spectra, was consistent with that given by pharmacological experiments. Conclusions The strategy proposed in this study could be applied to evaluate efficacy strength of CHM and helpful for screening candidate herbal drugs from different herbs or prepared by different technologies.