Graduate School of Pharmaceutical Sciences, Kyoto University.
Chem Pharm Bull (Tokyo). 2021;69(3):246-252. doi: 10.1248/cpb.c20-00769.
The terrestrial plants, Isodon japonicus (Burm. f.) H. Hara and Isodon trichocarpus (Maxim.) Kudô (Labiatae), are native to Japan. Different parts of these plants have been used as a traditional bitter stomachic, under the name Isodon herb (Enmei-so). Ent-kaurane diterpenoids are the major constituents of Isodon herb that contribute to the herb's medicinal properties. However, large variability with respect to the composition of these diterpenoids limits the suitability of Isodon herb as a pharmaceutical ingredient. Thus, an investigation of the factors that affect its chemical composition is required. In this study, the DNA-barcoding method, using internal transcribed spacer sequences of nuclear ribosomal DNA, was applied to cultivated and commercial samples of Isodon herb. Further, each such sample was separated into leaves, stems, and flowers and analyzed for diterpenoid content by HPLC. Moreover, the diterpenoid content in coarsely cut and powdered samples was evaluated. Results confirmed that the source species of these samples was I. japonicus or I. trichocarpus. The three major diterpenoids in Isodon herb were enmein, oridonin, and ponicidin. The diterpenoid content was affected by milling process. Moreover, the diterpenoid content was greatly affected by the ratio between leaves and stems in each sample. Thus, to accurately quantify the diterpenoids in Isodon herb, the use specific conditions such as drying using mild temperature conditions and avoiding milling of the samples might be necessary. This may help in regulating variations in the herb's composition, in turn, providing better quality and a safe herbal product for pharmaceutical use.
陆生植物，冬凌草（Burm. f.）和糙苏（Maxim.）（唇形科）原产于日本。这些植物的不同部位被用作传统的苦味健胃药，名为冬凌草（Enmei-so）。冬凌草中的贝壳杉烷二萜类化合物是其主要成分，有助于发挥其药用特性。然而，这些二萜类化合物的组成存在很大的可变性，限制了冬凌草作为药用成分的适用性。因此，需要研究影响其化学成分的因素。在这项研究中，采用了核核糖体 DNA 内转录间隔区序列的 DNA 条形码方法，对栽培和商业冬凌草样本进行了研究。进一步地，将每个样本分为叶、茎和花，并通过 HPLC 分析二萜类化合物的含量。此外，还评估了粗切和粉末状样品中二萜类化合物的含量。结果证实，这些样本的来源物种是冬凌草或糙苏。冬凌草中的三种主要二萜类化合物是冬凌草甲素、冬凌草乙素和 ponicin。二萜类化合物的含量受到粉碎工艺的影响。此外，每个样本中叶片和茎的比例对二萜类化合物的含量有很大影响。因此，为了准确定量冬凌草中的二萜类化合物，可能需要使用特定的条件，如温和的干燥温度条件和避免对样品进行粉碎。这有助于控制草药组成的变化，从而为药用提供更好质量和更安全的草药产品。
