[Chemical composition and antioxidant activity of different parts of Prunella vulgaris by UPLC-Q-TOF-MS/MS and UPLC]

Prunellae Spica is the dried spica of Prunella vulgaris belonging to Labiatae and it is widely used in pharmaceutical and general health fields. As a traditional Chinese medicine cultivated on a large scale, it produces a large amount of non-medicinal parts, which are discarded because they are not effectively used. To analyze the chemical constituents in the different samples from spica, seed, stem, and leaf of P. vulgaris, and explore the application value and development prospect of these parts, this study used ultrahigh performance liquid chromatography-tandem quadrupoles time of flight mass spectrometry(UPLC-Q-TOF-MS/MS) to detect chemical constituents in different parts of P. vulgaris. As a result, 117 compounds were detected. Among them, 87 compounds were identified, including 32 phenolic acids, 8 flavonoids, and 45 triterpenoid saponins. Some new triterpenoid saponins containing the sugar chain with 4-6 sugar units were found. Further, multivariate statistical analysis was conducted on BPI chromatographic peaks of multiple batches of different parts, and the results showed that spica had the most abundant chemical constituents, including salviaflaside and linolenic acid highly contained in the seed and phenolic acids, flavonoids, and triterpenoid saponins in the stem and leaf. In general, the constituents in the spica were composed of those in the seed, stem, and leaf. UPLC was used to determine the content of 6 phenolic acids(danshensu, protocatechuic acid, protocatechuic aldehyde, caffeic acid, salviaflaside, and rosmarinic acid) in different parts. The content of other phenolic acids in the seed was generally lower than that in the spica except that of salviaflaside. The content of salviaflaside in the spica was higher than that in the stem and leaf, but the content of other phenolic acids in the spica was not significantly different from that in the stem. The content of protocatechuic aldehyde and caffeic acid in the spica was lower than that in the leaf. DPPH free radical scavenging method was used to detect the antioxidant activity of four parts, and there was no significant difference in the antioxidant activity between the spica and the stem and leaf, but that was significantly higher than the seed. Moreover, the antioxidant activity of these parts was correlated with the content of total phenolic acids. Based on the above findings, the stem and leaf of P. vulgaris have potential application value. Considering the traditional medication rule, it is feasible to use the whole plant as a medicine. Alternatively, salviaflaside, occurring in the seed, can be used as a marker compound for the quality evaluation of Prunellae Spica, if only using spica as the medicinal part of P. vulgaris, as described in the Chinese Pharmacopoeia(2020 edition).