Rosmarinic acid in Perilla frutescens and perilla herb analyzed by HPLC

High-quality perilla leaves are defined as those having purple upper and lower surfaces and a pleasant smell. The Japanese Pharmacopoeia specifies the content of essential oils in perilla leaves but not the content of rosmarinic acid. Rosmarinic acid is a common component of Labiatae plants such as shiso (Perilla frutescens Britton var. crispa W. Deane). Rosmarinic acid has been reported to exhibit anti-inflammatory and anti-oxidant activity but the factors affecting the content of rosmarinic acid in plants remain unknown. This study describes a simple and reproducible method for quantifying rosmarinic acid. We elucidated the main causes for the different rosmarinic acid contents of plants by examining various samples of perilla using the proposed method. Significant differences in rosmarinic acid content between varieties and cultivators were observed. The rosmarinic acid content was higher in green perilla compared with red perilla, in wild species compared with cultivated species, and in plants cultivated in outdoor nurseries compared with in indoor nurseries. The proposed quantitative method was used to examine the rosmarinic acid content in a Kampo formula, Hangekobokuto, and was found to be higher in decoctions prepared using the Kouge method compared with the typical preparation method. We examined the chlorophyll and caffeic acid contents of several samples and their relationship with the rosmarinic acid content.