Abstract: An orthogonal experiment was conducted to optimize the ethanol reflux extraction process of total flavonoids from Clinopodium polycephalum,and a stable method for determining the total flavonoid content was established.Based on this,quality evaluations were carried out on 6 batches of Clinopodium polycephalum medicinal materials from different sources.The results showed that the optimal extraction process was 70% ethanol volume fraction in 3 hours and 2 extractions;the RSD of precision tests,stability tests,repeatability tests,and sample recovery tests of the nitrous acid-sodium nitrate-sodium hydroxide colorimetric method were all less than 2%,indicating the accuracy and reliability of the method;the total flavonoid content of the 6 batches of Clinopodium polycephalum medicinal materials ranged from 0.067% to 0.154%,and the batch-to-batch coefficient of variation was as high as 32.72%.Even for medicinal material samples from the same origin,the total flavonoid content still showed significant differences,suggesting that the quality uniformity of Clinopodium polycephalum medicinal materials currently circulating in the online market is poor.

Key words: Clinopodium polycephalum, total flavonoids, ethanol reflux extraction, orthogonal test, quality evaluation, ultraviolet-visible spectrophotometry