Standardization of Leonurus sibiricus L. aerial part and capillary electrophoresis quantitative analysis of its leonurine content

The quality parameters of Leonurus sibiricus L. aerial part crude drugs were evaluated. Fifteen crude drugs were collected from various locations throughout Thailand. The transverse section of the stem of L. sibiricus showed quadrangular character highlighted the ribs with angular collenchyma. The epidermis was uniseriate with abundant glandular trichomes distribution. Prismatic calcium oxalate prisms were found in the stem medullary parenchyma.The histological character of crude drug powder showed bordered pitted vessel, fragment of fiber, glandular trichome, prism crystal, spiral vessel, starch granule, and stomata. The loss on drying, total ash, acid-insoluble ash, and moisture contents should be not more than 8.18, 15.28, 4.04, and 8.91 g/100 g dry weight, whereas ethanol and water-soluble extractive values should be not less than 7.67, and 17.21 g/100 g of dry weight, respectively. Leonurine in the crude drugs were analyzed by capillary electrophoresis (CE) with photodiode array detector. The ethanolic extraction performed by Soxhlet apparatus yielded 18.86 ± 4.09 g/100 g dry weight. The electropherogram detected at 277 nm showed the migration time of leonurine at 6.2 min. The developed CE was found to be valid for leonurine quantification in L. sibiricus ethanolic extract. The contents of leonurine in 15 crude drugs ranged from 0.79 to 4.23 mg/g with the average of 2.38 ± 1.10 mg/g dry weight. This study established the pharmacognostic specification of L. sibiricus crude drug in Thailand with special reference to a bioactive compound, leonurine. CE was beneficial technique for the analysis of leonurine in L. sibiricus aerial parts.