异戊烯基黄酮-中药甘草清热解毒的重要功效成分

Objective To explore the functional ingredients of Glycyrrhizae Radix et Rhizoma clearing away heat and removing toxic substances, and then to provide ideas and references for the improvement of quality standards, and the secondary development, of this traditional Chinese medicine and its compound preparations. Method: Based on the quantitative antibacterial relationship of flavonoids reported by our group, the chemical structures of lipophilic flavonoids isolated from three species of licorice in Chinese Pharmacopoeia were collected and screened, and then their antibacterial activities were calculated. Simultaneously, the lipophilic ingredients, extracted with ethyl acetate from Glycyrrhizae Radix et Rhizoma decoction, were performed for the physicochemical analysis, spectral analysis and antibacterial test. Finally, the correlation between the function clearing away heat and removing toxic substances and these lipophilic flavonoids, of Glycyrrhizae Radix et Rhizoma, were further explored by the combinational analyses of some evidences of Chinese medicine classics, the research results and the literatures reported. Results: A total of 134 lipophilic flavonoid compounds form Glycyrrhizae Radix et Rhizoma were reported. Almost all of them are isopentenyl flavonoids containing 1 to 2 isopentenyl units. The calculation for the antibacterial activities of these flavonoids showed that they had strong inhibitory activity to Gram-positive bacteria, and those with the minimum inhibitory concentrations from 0.4 to 40.0 μg/mL were accounted for 94.0%. Simultaneously, the lipophilic ingredients in the licorice decoction present antibacterial activity, and contain the above possible isopentenyl flavonoids, especially isopentenyl dihydroflavones. Conclusions: The isopentenyl flavonoids are a class of important ingredients of Glycyrrhizae Radix et Rhizoma for clearing away heat and removing toxic substances, and also related to the efficacy of eliminating phlegm and relieving cough. Thereout, they can be considered as the screening range for the quality markers (Q-markers) of licorice, especially for the isopentenyl dihydroflavones. Furthermore, it is better for Glycyrrhizae Radix et Rhizoma to be ground into powder for preparing pills when it is used to clear away heat and remove toxic substances, and to eliminate phlegm and relieve cough.